Tele-Visionaries: The People Behind the Invention of Television

TEAM LinG

TELE-VISIONARIES

IEEE Press 445 Hoes Lane Piscataway, NJ 08855 IEEE Press Editorial Board Stamatios V. Kartalopoulos, Editor in Chief M. Akay J. B. Andersaon R. J. Baker J. E. Brewer

M. E. El-Hawary R. Leonardi M. Montrose M. S. Newman

F. M. B. Periera C. Singh S. Tewksbury G. Zobrist

Kenneth Moore, Director of IEEE Book and Information Services (BIS) Catherine Faduska, Senior Acquisitions Editor Anthony VenGraitis, Project Editor

TELE-VISIONARIES The People Behind the Invention of Television

RICHARD C. WEBB

IEEE Press

A JOHN WILEY & SONS, INC., PUBLICATION

Copyright © 2005 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008 or online at http://www.wiley.com/go/permission. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services or for technical support, please contact our Customer Care Department within the U.S. at (800) 762-2974, outside the U.S. at (317) 572-3993 or fax (317) 572-4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic format. For information about Wiley products, visit our web site at www.wiley.com.

Library of Congress Cataloging-in-Publication Data is available. ISBN-13 978-0-471-71156-8 ISBN-10 0-471-71156-X Printed in the United States of America. 10 9 8 7 6 5 4 3 2 1

To Virginia, for more than sixty years of patience and devotion

CONTENTS

Preface

ix

Acknowledgments

xv

CHAPTER 1

Introduction

1

CHAPTER 2

Who Invented Television?

5

CHAPTER 3

The Vacuum Tube Era

17

CHAPTER 4

Dr. Vladimir Kosmo Zworykin

25

CHAPTER 5

The Foremost Problem of Television

29

CHAPTER 6

Philo Farnsworth

37

CHAPTER 7

Television at Purdue University

41

CHAPTER 8

Sarnoff, Radio, and Early Television

47

CHAPTER 9

The RCA Laboratories Division

59

CHAPTER 10

The Evolution of Sensitive Camera Tubes

65

CHAPTER 11

The Field-Sequential Color Incident

77

CHAPTER 12

The Invention of Compatible Color

83

CHAPTER 13

The Shadow Mask Color Picture Tubes

89

CHAPTER 14

A Projector, Camera, and Triniscope

95

CHAPTER 15

Transmitting Color Pictures

105

CHAPTER 16

The Color Television Hearings of 1949/1950

113

CHAPTER 17

Delayed Broadcasting

125

CHAPTER 18

Goodbye RCA

131 vii

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CONTENTS

CHAPTER 19

The Beginnings of Digital Television

137

APPENDIX

Historic Report on Camera Tube Development

151

References

163

Index

165

About the Author

169

PREFACE

O

N THE MORNING of September 11, 2001 we were alerted to turn on our television sets, like being asked to look out of a window, and along with people in every part of the world, watched the cowardly surprise attack upon innocent U.S. citizens in their homeland by radical Muslim fundamentalists. With the north tower of the World Trade Center in New York City already in flames from the impact of a fully loaded commercial jet airplane hijacked by the homicidal maniacs, we next witnessed the approach of a second plane and its crash into the south tower. Before recovering from those shocking events, we were switched to cameras in the Washington, D.C. area to view the results of yet another plane that had just crashed into the Pentagon. Our world was falling apart as we watched it. Within minutes, we received word that a fourth commercial jet had unexplainably crashed into the ground on a Pennsylvania farm. Later, we learned that this plane, too, had been hijacked and was scheduled to kill all aboard as it crashed into the White House. Only by the heroic intervention of its brave passengers were the fanatics thwarted, but control of the airplane was unfortunately lost. What more can be said of the timely utility of our television system to make humanity aware of itself? After 50 years of visual contact with the expanded neighborhood that is our planet, it is already difficult for many of us to remember the provincial lives we once led. The majority of the present population has never known anything but this shrunken world! Whether this will prove to be a good or a bad thing for humanity will play out in time, but its permanent existence as part of modern life is indisputable. The engineers and scientists who participated in bringing this monstrous life change into the world probably never gave a thought

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PREFACE

to the enormous force for social change that they held in their hands. They were simply feeling their way, day by day, toward their goal of opening up a powerful communication medium. The television system they created was born in the age of slide rules and Newtonian physics books. Even the skill of scientific glass blowing was still in its infancy at the time the vacuum tube was invented. The word “electronics” was yet to be coined. The science that we now call electronics was once a black art. For a very long time it was practiced by obscure individuals, mostly hanging around in university physics and chemistry labs, some in home workshops. When the vacuum tube was invented, many of them quickly become amateur glass blowers so they could build tubes of their own invention. Sheets of asbestos could be seen everywhere an oxygen torch might point! Vacuum jars and bakeout ovens dominated workbenches in laboratories where the sound of the ever-present vacuum pump may still reverberate. These explorers were human, of course, and there were little pockets of jealousy and friction here and there, but, overall, they got along quite well. None of them had any money. Most were living on scholarship stipends or modest grants of some kind. When the business entrepreneurs finally discovered them and saw the vein of gold that could be mined, it didn’t take long for them to focus their resources and push the world into what was originally called the “age of radio.” Can anyone remember early AM radio? We had hardly gotten used to having telephones when we began to hear faint voices on radio headsets, with added squeals and crashes of static. Large paper-cone loudspeakers and battery eliminators! Freshly varnished cabinets and black Bakelite panels with mysterious dials, knobs, and meters! The aroma of that whole enchanting moment still lingers in my nostrils! It must be said that it was the entrepreneurial interest of the business community that launched radio broadcasting and then turned its attention to the complete sight and sound utility that we now call television. It can also be said that whatever fame and fortune these events produced settled almost exclusively on this latter group and upon the performing personalities who so quickly found this great new stage on which to exhibit their talents. It is the intent of this book to place in memory some of the quieter and less rewarded souls who were the ones who actually created the technical foundation upon which this huge communication industry is based.

PREFACE

xi

The catchword of the twentieth century seems to have been electronics or electronic devices and we now find ourselves totally submerged in them! In recent years, it has become so easy for equipment designers to respond to the real or imagined demands of the marketplace that almost any new product can be materialized almost overnight. It will be in mass production in six months and sell for under a hundred dollars and it will fit in your pocket! How do they do that? Entering the twenty-first century, the design of electronic products has been so greatly simplified by the availability of integrated circuit packages whose complex internal workings, like the basic machine language of computers, need never be understood by the applicators. Now, at a higher level, modern designers can quickly select the required pieces from thousands of interconnectable logic components described in the manufacturers’ catalogs. It’s a sort of “plug and play” situation as they call out functional pieces that will connect together in accordance with the general idea of a product. The idea and a logic plan for executing it are all that are really necessary. In just a few weeks, a working model will have been assembled and demonstrated to management. This will be followed with a cost reduction and miniaturization program which will fit it onto a tiny silicon chip. Just a colorful shipping container and a cryptic instruction manual are all that are needed now. Invention and materialization of new products in this manner has never before been possible. The story you are about to read chronicles quite a different path to building curious things, some of which turn out to be useful to mankind. At a few points it will stimulate your brain as you ponder the logic of obscure ideas seldom discussed. Most of us know more about how our automobiles operate than our televisions, DVDs, and computers. This book will bridge that gap a little bit and enable readers to better comprehend the new tools that are being placed in their hands almost daily. You will meet a few of the thoughtful people who enjoyed treading the adventurous path that has brought us into this new age of radar, television, hand-held computers, instant voice communicators, and a mountain of exotic new electronic stuff. Many of them were and are my friends and colleagues, and at some points the story inevitably drifts toward the autobiographical. Do not think of me as a historian chronicling all of this though, because I am simply one of the engineers who was there at

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the time it was happening, and I am just telling you what I saw. As to the dates and events that I did not personally observe, I have relied upon the writings of several of the full-fledged, honest-toGod, real live historians who make it their life work to keep track of those things. You will find their works in the References section. Do to the fact that the original concept of television anticipated that radio broadcasting alone would be its delivery medium, some last-minute additions to this story have had to be made. Widespread distribution of sight and sound via house-to-house cable wiring never entered the minds of the founding fathers of television. Certainly, the concept of broadcasting from satellites in the sky was pure science fiction. We thought that people would become accustomed to decorating their homes with multielement beam antennas attached to their chimneys, or “rabbit ears” in their apartments. Who could have anticipated that an army of “cable guys” would descend upon us with the capability to provide much better video quality than radio antennas ever did? For just a few dollars a month, trips to the roof were avoided, and this encouraged immediate acceptance. The development of color television as I saw it unfold is the primary thrust of the book, but stopping abruptly just as it was achieved would leave the reader at a point at which obsolescence was about to set in. This occurred just as cable and satellite delivery of very wideband (high-density) information transmission for computers became available. The sudden demand for a much more accurate and reliable communication system to serve the new personal computers offered an improvement for television as well. The computing devices forced the engineering community to come up with a radically improved communication technology that we call “digital,” and it seems essential to preview the essence of this new technology if only for sake of completeness. You may correctly conclude that this latter material might more appropriately appear as the topic of another book. One observation that I’m impelled to make about the real TV historians is that they seem so uniformly caught up in the romance of the very earliest technology that led to making any kind of electronic camera and display device that could produce just a crude image, that they have diminished the enormous scientific achievement that was necessary to establish a commercial-grade television industry. This leaves readers with the impression that

PREFACE

xiii

once crude input/output devices were available, all that was required to incorporate them into the world’s first visual connection with itself was simply routine engineering. The “cable guy” or the local service shop might just as well have done it! The scientists and engineers who played in that ninth inning of the game would disagree. Things were not all that simple when they immersed themselves in it as a lifetime work. The challenges they faced were every bit as great as those encountered by the earliest inventors. In this book, you will read about some of the problems that remained for them to conquer. RICHARD C. WEBB Estes Park, Colorado July 2005

ACKNOWLEDGMENTS

WORDS OF APPRECIATION To my former colleagues, Edwin Goldberg (d. 2004), Wendell Morrison, Alfred Schroeder, Dalton Pritchard, Les Flory (d. 2002), Win Pike, and Paul Weimer (d. 2005), my friends during those productive days at the David Sarnoff Laboratory, who have now, fifty years later, generously supported the preparation of this manuscript. To Dr. Douglas Gomery, professor of Journalism at the University of Maryland, who provided a much needed short course in writing while he relaxed at his mountain home in Colorado. To Dr. Alexander B. Magoun, Executive Director, David Sarnoff Library, Princeton, New Jersey, for his supply of pictures as well as his editorial coaching.

POSTSCRIPT I am dedicating this book to my friend Dr. Paul K. Weimer, who supported the preparation of the book from the beginning, contributed his own writing to parts of it, and gave it a thorough editing at the end. He passed away just a few days before I was to submit the finished work to the publisher. R.C.W.

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1

INTRODUCTION

T

ELEVISION IS UNQUESTIONABLY the most influential medium of mass communication ever invented. In the perspective of a halfcentury of its use, it is easy to see that almost every man, woman, and child on the planet has been affected by its presence. It has taken its place along with indoor plumbing and sliced bread as a natural part of our environment. The arrival of television at middle of the twentieth century was like wildfire in a wind. No one missed knowing about it because, almost immediately, it became the primary source of news, weather, and entertainment for all of us. As an advertising medium, it has no equal, as has been amply illustrated. It is easy to see how television benefits the lives of the aged and immobilized. From its inception, the technology of television (along with its cousin, radar), represented the highest level of electronic science that mankind had achieved. What began as an offbeat cult of curious home hobbyists with their squawky wireless radios, evolved into an entirely new industry whose electronic products now completely engulf us. The world of the early ham radio operators exploded in just a few years into the largest and most profitable business ever developed. It now employs a significant part of the entire population. Thousands of engineers, technicians, and professional managers have trained or retrained themselves for participation in the revolutionary new business called electronics, which by the end of the century had become the darling of Wall Street. The presence of video broadcasting systems, thirsty for around-the-clock program material, created worlds of opportunity for emerging entertainers, playwrights, musicians, and communicators, not to mention aspiring politicians. Most of the celebrities Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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and popular personalities of our present day have found their way into public view through the “small screen.” Can anyone imagine going back to a no-television world? In the beginning, all electronic products were bulky, fragile, and expensive. There was much to be done to make them ready for masses of rough, tough, and critical users. The urgent need for the radar and television technologies in a time of war created the first great incentive for manufactures to produce smaller, more rugged, and less expensive “radio parts,” as we used to call them. These are the basic building blocks from which all electronic equipment is made. Most of it had never existed before or, if it had, was of enormous size. The concept of printed circuit board wiring was the first step toward bringing uniformity, ruggedness, reliability, and lower cost to electronic devices. The really big step, however, came when vacuum tubes were replaced with transistors, and then later by the tiny integrated circuit chips that combine it all together. With amazing new materials and subassemblies evolving every day, TV receivers steadily improved and black-and-white screens got bigger and gave way to color screens as sales volume brought costs down. The sister fields of stereo sound recording along with AM and FM radio broadcasting also benefited from the availability of the ever-improving electronic components. In parallel with the entertainment products came the application of electronics to medical instruments, flight safety devices, automotive controls, business machines, home appliances, and, crowning all of them, portable telephones and personal computers. We continue to watch with amazement the evolving Earth satellite and space probe developments that have completely transformed our terrestrial communications. None of these things could have come about before our entry into the electronic age in which radar and television played such an important introductory role. Much of the driving force that pushed us into the new age of electronic technology came from American colleges and universities and from a few large industrial research centers that had the foresight and financial capacity to sustain high-level research programs. The engineering colleges took the drastic step of moving their teaching away from the macro world of Newtonian physics and the “things” that everyone could touch, see, and understand, over to the more abstract and noticeably more intellectual world

INTRODUCTION

3

of solid-state physics. At that point, many of the physical science departments welcomed the invading engineers rather coolly into their previously private hunting grounds. Nevertheless, the demands for a rapid broadening of knowledge in this field soon overcame that reaction. Not all engineering students took to studying the new, more rigorous, and abstract physics, and many transferred out of the field. To retain them, the colleges invented degrees in “engineering technology,” placing emphasis on the more practical aspects of the oncoming new age, and trained “application engineers” who would be able to set up and administer the startling new products their classmates were bringing into the world. Although the schools would train the new young engineers in mathematics and the basic sciences, turning them out with professional degrees, there was more to it than that. Other intellectual supports were needed to bring the existing engineering work force up to date, and these should not be overlooked. The professional engineering societies and technical magazines played a significant role in unifying the industry at that time. The Institute of Radio Engineers (later renamed the Institute of Electrical and Electronics Engineers), the Society of Motion Picture and Television Engineers, and certain excellent publications like McGraw Hill’s Electronics magazine, the Bell System Technical Journal, Science, and the RCA Review. These high-level monthly publications provided a common medium for the exchange of ideas throughout the industry. Furthermore, the annual conventions sponsored by those societies were always an inspiration. Corporate exhibitors vied with each other to place their latest technology on display, but we watched apprehensively as an army of inconspicuous Japanese engineers, in dark blue suits and with cameras in hand, plied their way through those wide open exhibit rooms, making their own plans for improving and miniaturizing everything they could catch in their viewfinders! As I look back on it now, they actually did a lot of good things, leading the way as they did to smaller, cheaper, and higher-quality electronic products, but we wish they could have done all that without creating a hardship for the very people who got the whole electronics industry started! The timely invention of the transistor at the Bell Laboratories in 1947 by William Shockley, John Bardeen, and Walter Brittain was really the “big bang” for the expanding solid-state electronic age. It was hard for everyone to see that immediately, and many of

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Large

Medium

Small

Integrated circuit “chip”

Figure 1.1 Transistors.

the vacuum tube engineers failed to appreciate their advantages. Some, myself among them, put signs on their doors saying help stamp out transistors. We old-timers were quite reluctant to embrace those expensive and temperature-sensitive little “pills” that gave no warning at all of impending failure. Under stress, a vacuum tube was always kind enough to glow red and blue and allow time for a quick power-down to save it from destruction. Until transistor construction changed from the original germanium material over to the much less temperature sensitive silicon in the early 1960s, they were just an attractive nuisance to many of us. But now, having rendered the delicate and bulky vacuum tube virtually obsolete (except for broadcast radio transmitters), transistors have made their massive transmutation into integrated circuits in which millions of them can occupy less than a square inch on a silicon wafer along with all of the interconnecting circuit wires (see Figure 1.1). It is easy to see how such extreme miniaturization would lead to the rugged, uniform, and reliable products that we now enjoy. A surprising by-product of all this is the dramatically lower construction cost that has come about through the use of photooptical mass manufacturing methods, which were quietly developed by an obscure and wholly unrecognized band of highly dedicated scientists and engineers. They are a whole separate story, and our hats are off to them!

CHAPTER

2

WHO INVENTED TELEVISION?

E

VERY CHILD CAN associate the telephone with Alexander Graham Bell, the electric light with Thomas Edison, and the airplane with the Wright brothers. But who do we think of as the inventor of television? Some want to give that honor to Zworykin, whereas others feel that American-born Philo Farnsworth owns the title. You decide for yourself! Actually, the development of television was simply too large an enterprise to have been the sole work of one gifted individual or even an inspired group. You might compare it to the construction of a large jet airplane, which we know would require the talents of a large number of skilled people whose identities and special abilities will forever remain unknown. In the case of television, however, there was a lengthy preamble of independent and uncoordinated effort undertaken by a great many dedicated scientists and engineers working privately all around the world. The concept of a technology that would enable humans to communicate with each other through their two principal senses, sight and sound, undiminished by distance, was a popular Jules Verne-type fiction for many years. A number of visionary writers (skipping the cartoon book and fiction writers) projected their ideas of the effects that electric picture connections would have on everyday living. The best known of these early writers on the subject of “distant electric vision,” and the most accurate predictor, was a prominent British electrical engineer, named A. A. Campbell Swinton, who proposed the idea of an entirely electronic video system in 1908. As desirable a prize as Swinton’s system would have been, the staggering physical difficulties inTele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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Figure 2.1 A. A. Campbell Swinton.

volved in creating it forestalled any immediate attempt to bring it about. By the last half of the nineteenth century, humans had compiled enough knowledge about the fine structure of matter as to be able to locate and process certain basic materials that had lightsensing and light-emitting properties. This encouraging work sparked the thought that Swinton’s system might ultimately be possible, but the world would have to wait until a means of amplifying weak electric currents was invented before any real progress on television could be made. The vacuum tube was the first of these. The scientists who were making the most important discoveries that led to the creation of our video system probably gave very little thought to the consequence of their inventions. Most of their work was done out of pure academic interest and a zeal for understanding more about the properties of nature’s materials. Some were probably motivated by social pressure to distinguish themselves as the first to discover this or that, and to reap whatever rewards might ensue. Regardless of their motives, we owe an enormous debt to all of those wonderful people, too numerous to identify here, for the knowledge they compiled for us. Television really began in 1884, when a 23-year-old German engineering student, Paul Nipkow, took the first practical step to-

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Figure 2.2 Paul Nipkow.

ward actually setting up a video system. He described, but never really built, a mechanical image-scanning device that he imagined could transmit pictures over wires like a telegraph message. His image scanning concept introduced the idea of a point-by-point, sequential inspection of a scene, left to right and top to bottom, just as our eyes scan a printed page. The time-varying brightness encountered at each successive point, he thought, would generate a pulsating electric current that could be transmitted over telegraph lines to a remote viewing point. Nipkow’s fundamental concept of the image scanning process is basic to the television system we use today. Imagine a postage-stamp-size window in a black sheet. Immediately behind the window, place a one-foot-diameter disk punched near its edge with tiny holes spaced apart exactly the width of the window. A light source behind the disk would cause each hole to trace a visible line across the window as the disk rotates. If each hole were to be placed a little closer to the center than the one before it, a vertical component would be added to the sequence of lines seen in the window. The lighted patch would then take on the appearance of a luminous surface, or tiny viewing screen, as the disk continues to rotate. In the very beginning, only a dozen or so scanning “lines” were crudely punched into a cardboard disk in order to create this

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Viewing Window Scanning apertures

Rotation

Figure 2.3 The principle of Paul Nipkow’s scanning disk idea is seen here. As the disk rotates, the apertures trace over the image field a line at a time, either reading scene brightness information as a camera, or releasing light as a viewing screen.

effect, but as soon as little moving images could actually be seen, fascinated experimenters began raising the scanning-line numbers upward through 24, 30, 48, 60, and 120 to improve picture clarity. The ultimate promoter of this mechanical scanning idea was John Logie Baird of Great Britain, who went up to as high as 240 lines in the mid-1930s. The scanning process served to convert light values into equivalent values of electricity that could be transmitted from point to point. For the image of a real object to appear on a screen like this, a duplicate scanning disk would have to exist at the remote location and run in exact synchronism with the viewing unit. The “camera disk,” as it would be called, would have a lens in front of it to project an image of the scene onto the surface of the whirling disk. A photoelectric light sensor positioned behind the disk would pick up the varying light intensity coming through the moving holes in the disk, converting it into an electric current in

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Figure 2.4 John Logie Baird.

proportion to the light intensity. Since no light sensor existed that could generate a large enough electric current to drive a lamp of any kind behind the remote viewing disk, an amplifier would have to be available to magnify that current. With this in place, the light intensity of the scene could thus be duplicated point by point in proper position at the viewing screen and would be recognized as a real image. Early photoelectric cells, made by Elster and Geitel in Germany in 1892, could have served as the light converters, but before the invention of the vacuum tube amplifier by Dr. Lee De Forest in 1906, there was simply no way to strengthen their very weak currents. Television (and many other things) would have to wait for De Forest’s invention. Because the mechanical method of scanning and reproducing television pictures had gained such a considerable lead over the entirely esoteric idea of a completely electronic system, television developers were split into two camps well into the 1930s. By 1928, Charles Francis Jenkins, for example, was regularly broadcasting mechanically scanned motion pictures late at night from a radio station in the Washington, DC area. As many as 2000 sets were said to be receiving his broadcasts at the time. In England, John Baird persuaded the BBC to start regular TV broadcasts

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Figure 2.5 Charles Francis Jenkins.

in 1930. Those broadcasts continued well into the mid 1930s, but when fully electronic pictures finally became available and were found to be so much better, they put an end to mechanical television forever, destroying Baird in the process. In an effort to build audiences for their broadcasts, Jenkins and several others began selling scanning disk kits that could be assembled by amateurs. Before the mid-1930s, however, excess inventories of these were being dumped on the market and one of my young friends was given one of them for Christmas. From Colorado, we searched many midnight hours looking for distant radio stations that might be sending out pictures. I can remember staring at the orange glow of the neon illuminator behind the scanning disk for hours, imagining that I could see some kind of a picture, but I can’t honestly say that I ever did. Early television engineers at GE and later at RCA had only the mechanical scanner to produce the steady, day-long video test signals needed in their lab, and that was a problem. No human or other life form could possibly face the strong lighting required to obtain a steady video signal from that type of very crude “camera” until Felix the (now famous) papier-mâché cat came along to stand on a rotary table for them. Figure 2.7 shows how he developed over the years.

WHO INVENTED TELEVISION?

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Figure 2.6 Scanner.

J. J. Thomson’s discovery of the electron in 1897 led to a wave of interest in electronic effects of all kinds, particularly electrons released from heated emitters. Use of the fast electrons to do what had never before been possible with heavy mechanical devices began immediately. Both television and oscillography were the first applications to benefit from the properties of the electron. Well before the electron was defined, however, the first sign of anything that could make a luminous mark on an evacuated

1929/60 lines

1934/343 lines Figure 2.7 Felix the cat.

1937/441 lines

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Figure 2.8 J. J. Thompson.

glass enclosure was described in 1878 by Sir William Crooke. He showed what he called “cathode rays” making a visible bluish fluorescence form on the walls of an evacuated vessel. The “rays” could be drawn from a cold metal surface by a high-voltage electric field (thousands of volts). No one then knew that this was actually the flow of electrons moving freely in an evacuated vessel.

Figure 2.9 William Crooke.

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In 1897, Professor Karl Ferdinand Braun succeeded in getting one of Crooke’s tubes to produce a small focused spot on a fluorescent screen. The spot could be moved by placing a magnet near it or by making the “ray beam” pass between electrically charged metal plates. In so doing, visible line traces could be made on the face of the tube. Here was the beginning of a simple means for forming an electronic “screen” or scanning raster for a television display. Ten years later in Germany, Professor Max Dieckmann built the very first real cathode ray tube using a heated cathode as the source of electrons. He also made a TV-type scanning raster and showed moving patterns on it by allowing electrical contact points to brush a rotating commutator running in synchronism with the scan. This was just a stunt to show a crude image on his tube and did not involve a photo-pickup camera. In 1911, the Russian physicist, Boris L’Vovich Rozing, at the St. Petersburg Institute of Technology, set up a similar Braun tube scanned in step with a mechanical camera to pick up and display real optical images. We assume that a vacuum tube amplifier was available for use in that experiment. The image he obtained was said to be dim and not well focused but it was probably the first live image ever displayed on an electronic screen. A student at the Institute at that time, and a favorite laboratory assistant to Dr. Rozing, was Vladimir K. Zworykin who was

Figure 2.10 Karl Ferdinand Braun.

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Figure 2.11 Max Dieckman.

postured by those events to carry on and greatly expand Rozing’s work, which he had so intimately witnessed. Zworykin remained at the core of electronic television development from that time all the way to his retirement from RCA in 1958. Since he added so many important improvements to Dieckmann’s original tube and to Rozing’s early experiments, Zworykin is generally seen as the

Figure 2.12 Boris L’Vovich Rozing.

WHO INVENTED TELEVISION?

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Figure 2.13 Zworykin with his iconoscope, the tube that brought us into the age of electronic television.

central figure in the development of the cathode ray tube and its application to television. It was my good fortune to spend a summer evening on the porch of his vacation home at Taunton Lakes, New Jersey in 1948 as he reminisced about his life and told about those first experiments with television.

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THE VACUUM TUBE ERA

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HE VACUUM TUBE has its roots in the work of Thomas Edison in 1883, although he didn’t know it at the time and he has never been credited with having had much to do with it. He was simply trying to find out why his new electric light bulbs were darkening and burning out so soon. At that time, Edison was the virtual king of everything electric and had the authority to legislate that only very low voltage DC current be used in his lighting systems because he didn’t want to start a fearful public reaction to the electric shock that was possible at higher voltages. It was noticed that the glass was darkening on the side adjacent to the positive terminal, which was also the side where the filaments were breaking. This suggested that there must be more current flowing at that point, heating it more than at other points. How could this be? Surely, no electric current could possibly flow through the empty space in an evacuated bulb! No? There was no logical explanation for this phenomenon at that time, as it was not yet known that electricity consists of a flow of tiny, negatively charged particles called electrons moving from the minus toward the plus end of any electrical circuit, including evacuated space. This would not be discovered for 14 more years! The direction of flow of the mysterious electric current had also been incorrectly defined years before in practical terms (which hold to this day) as flowing from the positive terminal of a battery power source toward the negative terminal via any continuous circuit such as a lamp filament or a motor winding that might connect them. This inverted perception of the true nature of electric current flow prevented Edison from seeing how an excess of current might converge upon and weaken a point near the positive end of his filaments. He passed it off as the “Edison effect” and did no more than file a patent claim on it in 1883. Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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In one of Edison’s experiments, he placed a metal foil inside a lamp and brought out a connection to it through the glass. Using a sensitive instrument to detect any current that might flow, he was surprised to find that when the foil was connected to the positive terminal, a small current actually did flow through the vacuum within the lamp. When the connections were reversed and the foil was connected to the negative battery terminal, current flow would cease. Notice how close he was to having discovered and defined the flow of electrons that has led us into the whole new world of electronics! What Edison had detected was the emission of electrons from a heated metal surface (thermoemission). His discovery of this effect brought him the only lukewarm recognition he ever received from the professional scientific community. Coincidently, Brittan’s first professor of electrical engineering (at Imperial College in London), Dr. John Ambrose Fleming, a former student of James Clerk Maxwell who had been appointed consultant for the Edison Electric Light Company of London in 1882 to help them set up the generators that would light the city for the first time, thereby became involved in the light bulb problem. His careful inspection of minute effects he saw in burned-out lamps as well as the “effect” that Edison himself had observed led him to conclude that a unidirectional flow of current was taking place in the lamps.

Figure 3.1 John Ambrose Fleming.

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At that time, the busy Fleming was also consulting for the Marconi Telegraph Company and was looking for a better signal rectifier (diode) to improve radio reception for that group. He soon saw the connection between Edison’s “effect” and a perfect rectifier diode for radio reception. He improved upon Edison’s experiment to make it more efficient, and named the new device the “Fleming valve” (see Figure 3.2). Marconi Radio found Fleming’s little valves (tubes) so much better than any radio detectors they had ever used before that they immediately put them into service in all of their telegraph stations. Although Fleming made the first of the new valves in 1883, it wasn’t until 1904 that he got around to filing for a patent on them. This caused a certain controversy as to whether he or Dr. Lee de Forest in America, who modified the Fleming valve into an electronic amplifier, should be considered the father of the vacuum tube. Electrons, acting like small negatively charged particles having both mass and velocity, remained a mystery, however, until 1897 when England’s J. J. Thomson discovered them and showed that electric charge or electron flow does indeed take place in the opposite direction to the previously defined electric current flow. By now, it was forever too late to correct that unfortunate mistake. The discovery that these extremely small, lightweight, and inherently negatively charged particles were part of the fundamental

Figure 3.2 One of the first Fleming “valves.”

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atomic structure of matter immediately stimulated intense study by the highest-level physicists in the world and Thomson’s electron theory was quickly verified. Impressive experiments were carried out wherein the size, charge, and mass of the electron were measured. Edison’s “effect” was now becoming fully understood. In 1906, de Forest, in America, placed a loosely woven wire grid between the heated filament and the plate of Fleming’s diode tube. He then showed that even when the plate was allowed to take on a large positive voltage, only a small negative voltage applied to the grid wires (repelling the electron flow) could completely control the size of the current reaching the plate! Something small was now able to control something large! Electronic amplification of weak electrical signals was thus invented. De Forest’s three-electrode (triode) tube (see Figures 3.3 and 3.4) marked

Figure 3.3 The first vacuum tube. This is one of the first vacuum tubes ever built. Lee de Forest engaged a NYC automobile lamp maker, H. W. McCandless, to construct a “special” lamp for him that had some extra parts in it connected to wires brought out through the top of the glass. The large, square plate element was shielded from the filament by a wire mesh grid. Voltage applied to the grid could dramatically control the flow of current from the filament to the plate and thus electronic amplification was born! This tube was built in 1906 and is in the Harry Houck museum, which is a repository for early radio treasures like this.

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Figure 3.4 Vacuum tube inventor, Dr. Lee de Forest, physicist and a private inventor, took John Fleming’s diode tube one step further by putting a grid shield between the filament and plate. A small negative voltage on the grid could take control of the current getting to the plate, thus creating the worlds first electronic amplification. This was and invention that would change the world!

the beginning of electronics everywhere and was the key element in all electronic inventions for at least 50 years before the invention of the transistor. Radio signals coming in from a receiving antenna are extremely weak, a few millionths of a volt at best, so they are very hard to hear with a pair of earphones and nothing but a diode rectifier, even Fleming’s new one. The first application of de Forest’s vacuum tube was therefore to amplify those weak radio signals so they could be heard better by the operators of the international wireless communication systems that had become so important to shipping safety. Enhancing de Forest’s work in the application of his tube to radio reception, another brilliant inventor, Edwin Armstrong, emerged (Figure 3.5). I so admire Armstrong’s work that I must tell you about him. While still an electrical engineering student at Columbia University, he made a careful study of the triode amplifier tube that de Forest had just brought forth, rigorously defining its operating characteristics. In his junior year, he displayed real genius when he invented “positive feedback,” which means taking a

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Figure 3.5 Major Edwin H. Armstrong.

portion of the output of a tube amplifier (basic gain of about 6 times) and feeding it back to the input, thus strengthening it as it loops through the amplifier. Using this technique, Armstrong was able to increase the amplification of a single vacuum tube up close to infinity, making it possible to tune in far-away radio stations that were never before audible. This caused quite a stir among the radio fraternity, because it was the first real breakthrough in radio reception. Armstrong called this a “regenerative” detector and it was immediately used in all of the first radio receiving sets. Even when I came along a few years later, everyone was still using Armstrong’s famous circuit to tune in short-wave stations from all over the world. de Forest seemed to think that he had thought of it first and challenged Armstrong over the matter all the way to the Supreme Court. The court decided in favor of de Forest, but all the radio engineers I ever knew always sided with Armstrong. Great as it was, the regenerator was delicate and difficult to handle (unfriendly to users). It was the source of the famous squeals of early radio which didn’t stop until Armstrong himself later invented the superheterodyne radio circuit that could develop extremely high amplification without the squeals, and be easily tunable by anyone. AM radio broadcasting has always been plagued by sensitivity to electrical discharges of all kinds, from vacuum sweepers to

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Figure 3.6 This is the first high-sensitivity radio receiver ever built! It was capable of world-wide reception due to Armstrong’s invention of the regenerative (positive) feedback circuit.

lightning, which causes annoying crashes of static in the received sound. Armstrong dedicated himself to overcoming this disturbance and was quite successful in doing so. He observed that by allowing a radio carrier to always run at full strength rather than be weakened by modulating it’s amplitude to imprint the sound message on it, the full strength signal had a very large noise quieting effect. By modulating just the frequency of a full-strength carrier, the quieting effect still holds and the sound comes through much better. He called this his frequency modulation (FM) system and set about to teach the radio broadcasting industry how to convert over to it. He hadn’t counted on the resistance this idea would get from the existing AM broadcasters, and particularly from David Sarnoff of RCA, who already had such a big stake in producing AM transmitters and receivers. Undaunted, he drove ahead with FM on his own, setting up a high-quality broadcasting station in Alpine, New Jersey in 1937 to

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demonstrate the advantages of FM. He programmed fine classical music all day long, quiet, no static, I loved to listen to his station from Princeton. The broadcasting industry of the time, having struggles of its own, continued to ignore Armstrong’s last breakthrough and in misery over the rejection he received for his efforts, he jumped from his hotel room in 1956. In 1947 William Shockley, John Bardeen, and Walter Brattain at the Bell Labs invented the transistor but it was not until the 1960s that transistors were ready to be designed into commercial equipment. There was, therefore, a 50 year period between the first appearance of vacuum tube amplifiers and the tiny, reliable and low-cost transistors and microchips that so greatly expedite the construction of complex electronic systems. As we think back on it, what was it about vacuum tubes that makes it so easy for us to wipe them out of our minds and overcome any impulse to make any further use of them? As important as those Fleming diodes and de Forest “audions” were at the time of their invention, opening the way as they did to the world of electronics, they had certain inherent limitations and obnoxious features that we engineers always had to live with and try to work around. Here are some of the most evident: 앫 Delicate, bulky, heavy, low-current devices 앫 Required substantial power to heat the source of charge carriers 앫 Only negative charge carriers (electrons) were available, making more convenient bipolar circuits impossible 앫 Required uncomfortably high circuit voltages—150 volts or more, versus 12 volts or less for transistors 앫 Interelectrode capacitance and long lead wires limited useful operating frequency range (system bandwidth) 앫 Heavy power consumption created heat ventilation problems and added to circuit noise Despite all of the shortcomings of vacuum tubes, we engineers had no alternative but to carry out the design of the original television system using them. It is something of a miracle that a TV system like ours, conceived and executed in the vacuum tube and slide rule era would turn out to be flexible enough to grow without interruption and withstand the enormous modification necessary to bring about today’s colorful system, which has already served us for half a century.

CHAPTER

4

DR. VLADIMIR KOSMA ZWORYKIN

V

LADIMIR KOSMA ZWORYKIN was born in 1889, in Murom, Russia about 150 miles east of Moscow. The Zworykins were a well-established merchant-class family. Vladimir was one of seven children. He graduated from the St. Petersburg Institute of Technology in 1912 with a diploma in engineering. His father wanted him to return to Murom and help run the family steamship business, but Vladimir had other ideas. Gifted with a most remarkable capacity for gentle persuasion, he talked his father into allowing him to continue his education in physics at the College de France in Paris, which had been highly recommended to him by his physics Professor Boris Rozing. Although Professor Langevin there loaded him heavily with the physics experiments of the day, Zworykin found time to discover radio communication and broadcasting. When it was announced that World Standard Time signals were about to be transmitted regularly from the Eiffel Tower, his interest was sparked to build a radio receiver to receive the signals. This soon developed into a full mastery of both receiver and transmitter construction, which would serve him well later in the practical world of military communications. Zworykin was perceptive enough to know at that time that he was weak in the theoretical aspects of modern physics, so in 1914 he obtained permission to transfer his graduate studies to the Charlotteburg Institute in Berlin, where he was readily accepted. That move didn’t work out, however, as a war between Germany and Russia broke out just as he arrived on the campus. This caused him some exciting moments as he made his escape back to Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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Figure 4.1

Vladimir Kosma Zworykin.

St. Petersburg via Finland. To make matters worse, he was immediately inducted into the Russian army as a private despite his high level of education. Having been trained as an engineer, however, he was given an “engineering badge,” which served him well in negotiating with the officers since engineers were in short supply and highly respected. He was first assigned as a teacher at the Officers Radio School, which put him in touch with the Marconi Russian Wireless Company where the most advanced vacuum tubes and radio equipment were being manufactured. He was soon advanced to the rank of Lieutenant and placed in charge of what we would now call “quality control” in their factory. Among the many projects that were handed to him there was an assignment to build what was probably the first two-way aircraft radio ever attempted for a Russian airplane. That project was not a success, however, as the delicate vacuum tube part of it which he had mounted on a simple wood board was violently torn apart by the vibrations of the airplane. Such chaos reigned in Russia at that time that Zworykin decided to find some way to obtain an assignment outside of the country. With his usual negotiating skill and certain contacts that his many family connections afforded him, he was able to attach himself to a geology professor who had a scientific assignment outside of the

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country that amounted to an Arctic expedition. Leaving on an icebreaker in 1918, he eventually arrived in London where the papers he carried were promptly refused because the English government did not recognize the current Russian regime. Fortunately, he got support from the American ambassador, who arranged his visa and a passage on a luxury liner to the United States. He was capable of paying his own way at that time. He had his first view of the Statue of Liberty on the first of January, 1919. The shaky “cooperative organization” of the fast-fading national government operating from Omsk, whose papers provided the clearance he needed to leave Russia, continued their wireless contacts with him, urging his rapid procurement of the radio materials he had been sent to obtain for them as well as many private requests for all sorts of things. At that point, Zworykin could have sought political asylum in the United States and simply ignored the requests for his return but, unexplainably, he seemed to feel a responsibly toward his homeland, and probably some apprehension about life in a country whose language he knew little of, so he simply carried out his assignment and accepted a prepaid trip back to Omsk. The return trip took him by train across the United States for a departure from Seattle in early April of 1919. After six more weeks of travel that included a stop in Japan, he reached Vladivostok, which was still in the hands of the struggling, “AllRussian” government. What he saw on that trip across the country via the Trans-Siberian railroad to Omsk, however, was so horrible that he immediately determined to go back to America permanently and as soon as possible. Now an experienced traveler, it was easy for him to obtain a commission as a government courier and almost immediately he was on his way back across Siberia to Vladivostok and on via Yokohama, Tokyo, and Honolulu to San Francisco, arriving there in August of 1919. This time, when he reached New York there was no allied government in Russia to bring him back; the communists had taken over. Zworykin would spend the rest of his life in the United States, but he needed a job. As it turned out, the Westinghouse Electric Company, a Manufacturing Company in East Pittsburgh, Pennsylvania was at that time in a cut-throat competition with the General Electric Company for just about everything electrical (including the skilled people who could design and build those things). Westinghouse was hiring many of the Russian engineering and scientific émigrés and

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some of them were aware of the arrival of the young Zworykin. He soon got a helping hand from them that led to his employment by the Westinghouse research Laboratory. This was just exactly where he wanted to be. Although there were several momentary glitches in Zworykin’s early employment there, and it was clear that Westinghouse was never much committed to supporting research on a subject as far out as television, Zworykin was able to stay fairly close to his pet subject despite the many excursions he was required to make into the design of other more urgently needed types of radio equipment. Fortunately, he had the opportunity to continue his studies in graduate physics at the University of Pittsburgh, where he obtained the Doctor of Philosophy degree in 1926. He had two major objectives for his research in television. First, he wated a cathode ray display large enough and bright enough to be easily viewed by several people in direct room light, and second, he wanted an electronic camera tube that would have light sensitivity comparable to that of photographic film. In 1923, he filed a patent on an electronic television system that included what would later be called an “iconoscope” camera pickup tube. His concept of the tube was so far in advance of the technology needed to build it, however, that early versions of the tube performed poorly (not producing a clean picture) and were never shown publicly. Only with help from some of the highestlevel scientists and technicians in the country was he finally able to bring the tube up to a commercial level of performance. The controversial patent on the tube was not granted until 1938. The cathode ray display tube (CRT), which he named the Kinescope, came along much faster than did the camera tube because in addition to his own ideas on it’s design, he kept a watchful eye on what other people were doing in the field everywhere. Zworykin was a relentless do-it-now type of person the kind that says, “We’ll worry about the details later.” This is how he found the high voltage electrostatic focusing system for the tube as well as an extremely important design technique known as “electron optics” (developed by Germany’s Hans Busch), which finally brought precision into the design of all cathode ray tubes from that time on. By mid-1929, Zworykin had put it all together and was able to demonstrate the very first sharp and bright CRT. He also had several patent interference cases on his hands.

CHAPTER

5

THE FOREMOST PROBLEM OF TELEVISION

A

S THE IDEA of extending man’s sight from a few feet to countless miles by electrical means became a popular topic of conversation, the need to scan the source image on a line-by-line basis as proposed by Paul Nipkow was evident enough and quickly understood. Photoelectric cells could convert light into electric current that would travel through wire lines to some distant point where it would be converted back to light again for viewing. It was apparent that there never would be any photocells sensitive enough and powerful enough to directly power a light that could be viewed through a second spinning Nipkow disk as a reconstructed image. The invention of the vacuum tube, however, offered hope that the magic of electronic amplification could overcome that shortcoming of photocells, and to some extent this was true. Dim images were beginning to be seen on the tiny screens of those early mechanical scanners, provided that enough light could be applied to the camera. A crude form of television thus did exist, but we were far from having the makings of anything like a commercial system. The main thing that was missing during those first efforts to extend our vision was the light sensitivity of the camera. People working in film photography were having the same problem at about the same time because nature puts a limit on the light level that will activate a chemical reaction in a layer of film sufficient to darken it. The photographers had one advantage over the television developers, however, in that they could lengthen the exposure time of a still image to whatever time it took to activate the film. Remember how those early tintype photos were taken? Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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The television scanning process does not deal with still images, hence there appeared to be no opportunity to extend exposure time to gain light sensitivity. With the scanning aperture constantly on the fly, only the light available at each picture point at the moment it is touched by the scanning probe is available to work with. Because this is so small, the Nipkow scanning disk was predestined to join the scrap heap. Only the idea of scanning a scene line by line would remain of it, but many people still thought that the conversion from mechanical to electronic scanning would be the utopian solution to everything and would suddenly bring us into the world of all-electronic television. That wasn’t true, of course, it was basic camera light sensitivity that would make or break television. Professor Max Dieckman and one of his students, Rudolf Hell, at the University of Munich, patented an electronic method of scanning with a unique vacuum tube in 1925. They called it an “image dissector,” but it was a nonstorage devise like Nipkow’s and there is no record that they ever tried to build one. They probably foresaw the limitation imposed by the light-sensitivity problem. How then has the sensitivity of an image scanning camera been raised to match the best photographic film cameras and make television possible? One word says it all, storage, and by that we mean light storage. When a television camera scans through roughly 250,000 picture elements in a scene, there are 249,999 units of time when each picture element is on its own and could be converting light energy into an equivalent electric charge, accumulating it for release at the next moment the scanning probe arrives. The size of the charge would then be that many times larger than what a nonstorage camera could produce. This is really an increase in exposure time for a television camera, and neither the Nipkow disk nor Deickmann’s image dissector tube could provide this vital light sensitivity enhancement for natural lighting conditions that would lift a picture signal above the inherent background noise of the ongoing amplifiers. I think that Dr. Zworykin understood this concept of light storage when he began making his first camera tubes because he always used illuminated photosensing elements mounted in such a way as to obtain continuous charge storage. Although the results from his early tubes were very discouraging, that was simply because no one had yet learned how to make uniform storage elements.

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Figure 5.1 Kalman Tibanyi (1897–1947).

While Farnsworth and Zworykin were busy working on their separate ideas for electronic camera and display devices during the 1920s, so were other people all around the world.* One noteworthy Hungarian physicist, Kalman Tihanyi (Figure 5.1), for example, was a prolific inventor who felt that he and not Zworykin, had uniquely invented the storage principle, and he obtained a patent on it in 1926. Perhaps he did, but he had no success in interesting any of the European electrical companies in backing him in doing further research on the subject and he finally sold his patent rights to RCA in 1934. The Zworykin camera tube, later called the Iconoscope, was the first electronic pickup device that had enough light sensitivity as well as image resolution to encourage people to believe that a high-quality public image transmission system could ultimately be developed around it. His tube was thus the springboard from which the television system we know today was launched. Nothing of its kind had ever been built before and no more than half a dozen other people in the world were trying to do the same thing. They would find each other later in the patent law courts. Of all of them, Zworykin’s Iconoscope would be the lone survivor. *Kalman Tihanyi in Hungary, Franscois C. P. Henrouteau in Canada, George J. Blake and Henry D. Spooner in England, Riccardo Bruni in England, S. I. Kataev in Russia, Kenjiro Takayanagi in Japan, and probably a few others.

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FOOTSTEPS TO AN INVENTION Upon his second arrival in the US in 1919, Zworykin was fortunate to obtain almost immediate employment with the Westinghouse Electric Company through influence from friends from his native land who were also helping him transfer over to the English language. His assignment at Westinghouse, however, did not include the development of television. He was hired for his knowledge of radio transmitters and receivers. Zworykin would have to try to steal a little time here and there, finding scrap materials with which to assemble a CRT viewing monitor and then a Nipkow scanner to show crude pictures to his associates who might then become interested in his plans for developing electronic television. Along the way to this objective he was found out, but his tireless activity generated enough interest among company officials to persuade them to overlook it and allow him to continue this activity as a coolly approved secondary use of his time. Finally, they gave him authorization to make modest use of the company’s glass blowing facilities, which opened a path to exploring ways of building camera tubes. Not many projects this big have ever gotten off with such a meager start! Armed with the experience he had had a few years back in Professor Rozing’s physics lab at the St. Petersburg Institute, and already competent in making photoelectric cells, he visualized a row of tiny cells which he would scan electronically in the television fashion. Reading from one of his early notebooks, I see that he started with just seven photosensitive elements. This would allow him to search for the best photosensitive materials and ways of mounting and scanning them. Over time, he learned how to make a fairly good row of photosensors, which, when scanned repeatedly, would make an image of seven vertical bars on his improvised CRT display. To obtain a two-dimensional image, he placed a rotating polygon mirror in front of the camera lens so as to sweep a two-dimensional scene like a cross or circle into the camera for the amazement of his friends. In those early days, a 60 line television picture would mean a 60 by 60 square matrix of picture elements or 3600 pixels. This was easily achieved using a Nipkow disk but it was on the high side when each element had to be hand made. Zworykin and his two or three associates therefore made a sequence of these seven

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pixel tubes, keeping a careful record of their construction and performance. A day of reckoning came, however, when the Westinghouse management wanted to see the progress that was being made on television. At that moment, all that Zworykin could produce was a dim picture of a cross on a sheet of paper, which didn’t impress them a bit. A suggestion was even made that he should “go do something else.” It takes a lot of determination to stay focused on your objective in the presence of such enthusiasm from management! Fortunately, that event occurred at about the time when David Sarnoff was just merging the little Westinghouse television group with those from GE in the new RCA manufacturing plant in Camden, New Jersey, the former home of the Victor Talking Machine Company. This placed Zworykin on much firmer ground and opened a much larger pocketbook for camera tube development. It seems that luck was always on Zworykin’s side, as you will see. At this point, serious work now began on full two-dimensional image targets. With the addition of Dr. Gregory Oglobinsky, a French physicist, as well as Harley Iams, Les Flory, and Arthur Vance to the group, serious work began on light-sensor arrays that could be scanned by an electron beam to form recognizable pictures. In the beginning, their light-sensitive targets were always scanned from the rear (double-sided targets). They pressed silver pins into insulated holes in a metal plate and scanned them from the rear. To obtain light sensitivity, they oxidized the image side by evaporating certain cesium compounds onto the silver pins’ heads. Photoemission then allowed electrons (negative charges) to depart from the pins, thus leaving each of them with a small positive charge (voltage). Such charge could accumulate on the capacitance formed between the pin body and the metal plate. This was clearly a light storage type of tube. Scanning was done on the back side of the plate, using an electron beam, which with our present knowledge would be recognized as being much too high velocity (too strong), generating undesirable secondary emission effects. Nevertheless the beam brought the pins back to a roughly uniform potential after each scan, discharging them through a signal resistor and thus generating a video voltage that would be sent to the viewing screen. It is easy to see that a very crude picture would come from such an arrangement, laborious as it was to build. Rob Flory, grandson of

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Les Flory, who was one of Zworykins lifelong assistants, has in his possession some of those original silver pins, and I have actually held them in my hand. Early in 1931, a tube was built that would be scanned from the front side, despite much opinion that the mixture of the scanning electrons with the liberated photoelectrons would interfere with each other. To the happy surprise of all, however, the singlesided target produced a much better picture than had ever been seen before. It had been hoped that a single-sided target might lead to the elimination of the pin-by-pin assembly process and to easier ways of placing a greater number of pixels on the target plates. Single-sided targets of all kinds were tried, starting with insulating films from very thinly peeled mica sheets. Individual pixels were then formed by evaporating a silver film through a screen, which would then be removed. Alternatively, the surface could be physically ruled to create little private islands of silver. The back side of the mica sheet was given an overall deposit of platinum to form a common-signal (out) plate. Before the silver side could be photosensitized, however, it was necessary to bake the assembly out to clear it of gas and other surface contaminants. One day, a technician (Sanford Essig), while attending the bake-out process, accidentally left one of the silver films in the oven too long. Upon examination, he noticed that the silver surface had spontaneously broken up into a beautiful mosaic of tiny silver globules, all insulated from each other and clinging to the mica. Although there would be months of experimentation to perfect that process, here was a way to easily obtain millions of tiny silver globules, all insulated from each other and stuck to the insulating surface. There would be no more ruling machines! Moreover, the tiny dimension of the silver droplets would enhance the image resolution of the iconoscope by a quantum leap. Figure 5.2 shows a cross section through the Iconoscope in its final form. By the late 1930s the iconoscope had become a very good pick-up tube, as measured by viewers who were seeing television for the first time. It could produce amazing pictures both indoors and out, as when Sarnoff used one to launch RCA’s experimental television system at the World’s Fair in 1939. There were several features of the tube, however, that led to its early obsolescence. One was its awkward shape and the large lenses that it required. It was almost impossible to design a conve-

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THE FOREMOST PROBLEM OF TELEVISION

Mosaic (S) Photo sensitive elements

Signal plate

Mica insulation

Mosaic

A2

Signal lead

Gun

Figure 5.2 Cross section through the Iconoscope.

nient lens-selection turret for that tube. Another was a flaw that appeared as a darkening cloud in the pictures it produced. This came from secondary emission effects that were still taking place in the tube. The cloud moved around randomly over the picture in accordance with the position of some highlight in the scene. Although this could be hidden (almost) by an adjustable shading compensator under control of a sharp-eyed individual, it was a big operational nuisance. It is easy to see why research on pick-up tubes would continue! Notice how far we’ve come in just this chapter. From a sevenby-seven pixel, crude image of a simple cross, to a crisp 525 line view of any black and white motion picture film you might want to deliver to a viewing audience. I will never forget that first day in 1945 when I arrived for work at the RCA laboratories. The film Gunga Din was being projected onto an iconoscope under the supervision of Al Schroeder (who would become my lifelong friend). I watched a crisp and high-quality black-and-white picture on the 12 inch studio monitor there in the control room, where actors Cary Grant, Douglas Fairbanks, Jr., Victor McLaglen, Sam Jaffe, and Loan Fontaine were gaining their early fame.

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Figure 5.3 Original report describing the development of the Iconoscope.

You may want to look through photocopies of a few pages of the original summary report describing the development of the iconoscope (Figure 5.3) that I have placed in the back of this book as an Appendix (see page 151). It was written by Harley Iams shortly after RCA’s television development group was formed and began its work in the Camden, NJ, factory. It was apparently Dr. Zworykin’s personal copy and is now in the hands of Robert Flory, who has graciously shared it with us.

CHAPTER

6

PHILO FARNSWORTH

I

N THE EARLY, tender years of television development, few people understood the difference between storage and nonstorage in a pick-up tube, and some of the early experimenters simply ignored the necessity for light storage in their pickup devices, which would have made them compatible with real-world lighting conditions. They were content to light their scenes (which were frequently motion picture films) with high-powered arc lamps. One of these experimenters was a young man by the name of Philo Farnsworth (Figure 6.1), who at the age of 14 is credited with having invented the (nonstorage) “image dissector” tube. He received much praise for his perception of an electronic method of scanning that would eliminate the pesky Nipkow scanning wheel. As the story goes, on a blackboard in his Rigby, Utah high school in 1922, the 14-year-old boy sketched out the idea of an electronic tube that would convert a light image into an equivalent electronic charge image in which electron density would substitute for scene brightness. The electrons would be subject to electromagnetic forces for scanning, thus eliminating the need for mechanical scanning. Farnsworth’s high school chemistry teacher, Justin Tolman, verified the concept of how such a tube might work and was as greatly impressed with his student as he was with the idea of the tube. Although not yet trained at any serious level of science, Farnsworth seems to have been a natural genius in the world of physics. The tube, which he specifically described as an “image dissector,” is without question the very first demonstrable, electronically scanned camera tube. It is simple to make and can produce beautiful pictures if given enough light. The tube is useful for Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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Figure 6.1 Philo Farnsworth.

certain purposes. Farnsworth applied for a patent on the Image Dissector in 1927 and his family members have always insisted that he is, therefore, the undisputed father of modern electronic television. A Salt Lake City businessman, George Everson, volunteered to set up a garage laboratory and obtain modest financing from a small local group that was interested in backing Farnsworth’s novel idea. As time went on and the nonstorage tube simply could not be brought up to a financially productive state for use in television broadcasting, the investors became dissatisfied with progress and new financing had to be sought. This scene repeated itself many times over the years. Unfortunately, the attention that Farnsworth received in his youth was really a burden to him because it forced him into a lifetime of trying to perfect that ill-fated tube he had invented in his youth. At an age when he should have been a graduate student in advanced physics at one of the major universities, he was working with untutored assistants in an unstructured and poorly financed laboratory in California. Although he matured into a distinguished engineer on his own, inventing many circuits and other important electronic devices, particularly, low-noise amplifier tubes, most of his inventions were peripheral to his first one.

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The idea of the tube is based upon spontaneous emission of electrons (in vacuum) from a light-sensitive surface acting as if it were a sheet of photographic film. Bright spots in the scene liberate more electrons from the surface than dark spots do. The electrons are drawn away from the photocathode by a strong electric field that moves them altogether, as a sheet, almost instantly to the far end of the tube. A strong axial magnetic field holds the image electrons firmly in their relative positions (holds focus) as they travel. A pinhole port in a metal plate at the end of the tube becomes a scanning aperture or exit port for the arriving sheet of electrons. Scanning of this electron image is accomplished by magnetically moving the entire sheet of image electrons back and forth over the exit hole, just as you might slide a photographic negative over a dot on a sheet of paper. Electrons representing the light intensity of just one picture point at a time thus pass through this fixed scanning aperture and from there on to the outgoing video amplifier circuits and viewing screen. The tube has an infinite life since its only source of electrons is from the photocathode surface itself, and it is completely immune to image burn since there is no place for the scene to be stored and burned in. Another feature is the easy control of the size and shape of the scanning aperture, which is simply a hole punched in a metal plate. A rectangular hole, tall and narrow, produces more high-frequency image detail than the round scanning beam that electron-beam-type pickup devices use. As a pickup tube for scanning slides and motion picture films, the tube has no equal. Given unlimited light, the Image Dissector, with its perfectly linear gray scale and high resolution, can produce the ultimate video signal. A drift tube like this has a serious light sensitivity problem, which arises from the fact that there is simply no way to intensify the electron sheet before scanning takes place. The electrons arriving at the receiving port are just the ones released by the photocathode at the moment of scan. Except under extreme brightness, this generates such a small video signal that it sinks into the everpresent noise of the amplifiers and produces a very snowy picture. A much more sensitive photocathode might fix the problem if that were possible, but natural physical laws prevent it. Farnsworth, apparently unaware of these limitations, worked a lifetime attempting to overcome them. Along the way, he was a leader in the improvement of photosensitive surfaces and low-

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noise amplifiers, becoming very well known and quite expert as an electronic engineer. He invented many circuits and techniques widely used in television, which brought him much respect. Working against one of nature’s obstacles, however, he never was able to bring the Image Dissector tube up to a commercially usable level.

CHAPTER

7

TELEVISION AT PURDUE UNIVERSITY

P

URDUE UNIVERSITY WAS one of the U.S. colleges where a few professors and graduate students were working on television in the 1930s. The original work was supported by the GrigsbyGrunow company in Chicago, which was willing to spend modest funds to keep abreast of this promising new field. The Purdue Research Foundation filed patents on several of their inventions which gained the attention of RCA and brought them into a unique relationship. Professor Roscoe George and his associate, Howard Heim, produced several fundamental patents on the design of cathoderay tubes, building them in large chemical flasks. The flat bottoms became the screens upon which they deposited brilliant white phosphors (earlier screens had always been green). The pictures seemed quite spectacular to people (like myself) who had never seen an electronic display before. Purdue’s 60 line experimental TV broadcasting station operated on a frequency just above the AM broadcast band and transmitted motion-picture films of BigTen football games, two evenings a week, from 1934 through 1939. Viewers reported seeing Purdue’s broadcasts from one side of the country to the other. Professor George was particularly well known for his fundamental studies of lightning discharges, which had occasioned his creation of an unprecedented cathode-ray oscilloscope tube. It was a metal tube and had to be continuously pumped to maintain its vacuum. The viewing screen in it was viewed through a glass port, which could be covered to protect a spool of photographic film that was used to make permanent records of the suspected Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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Figure 7.1 Purdue University’s broadcasting station.

high-frequency structure of lightning discharges. The instrument was way ahead of its time since by squeezing the deflecting plates very close together, it could show frequencies well into the gigahertz range. Quite an instrument for the 1930s! George and Heim’s (Figure 7.2) activity at Purdue is noteworthy because it shows how an academic institution could generate nearly a dozen fundamental ideas that were useful in furthering television technology. The inventions ranged from electron gun

Figure 7.2 Roscoe George and Howard Heim as I knew them.

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Figure 7.3 Professor George with the Nipkow film scanner.

construction that was of particular interest to RCA to those first white-phosphor CRT screens. Among them was the circuit technology for generating high voltage for the CRT screen as a by-product of the ever-present horizontal sweep impulses (Farnsworth was probably first to employ this technique). Purdue pioneered the use of blacker-than-black picture synchronization which, except for England, has became the world-wide standard of broadcast picture polarity. It was later proven in court that the Purdue scientists were not the very first to do some of these things but it is easy to see that they were in the vanguard group whose members often collided in their pursuit of current technological objectives. In 1929, Professor George published a technical paper pertaining to his electrostatic focus and beam acceleration techniques for cathode-ray tubes. This was of such interest to RCA that they sought licensing rights to the patents. In its contract arrangement with the University, RCA set up a graduate student fellowship program to support further research on television technology at the school. The RCA funds were first available in 1939 and were used to bring in several graduate research fellows that year. This is where my career in television began.* We “fellows” worked with *I was in good company when you consider what some of the others did later: George E. Mueller became director of NASA’s Apollo moon landing project and is also known as the father of the space shuttle, John W. Rieke became director of Bell Lab’s Indianapolis Laboratory, and Robert P. Stone became manager of production engineering or RCA’s color picture tube factory in Lancaster, PA.

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Figure 7.4 Howard Heim, Roscoe George, and department head C. Francis Harding with the Purdue television receiver.

George and Heim to dismantle the now obsolete 60 line mechanical scanning system and undertook the construction of what was to be a new 441 line all-electronic station. We all regret that the intervention of World War II prevented us from ever bringing that new station to completion. During the course of the war some of the graduate students were held out of military service and called upon to work on pro-

Figure 7.5 The 60 line screen image is of Mrs. Rosa George.

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Figure 7.6 The Purdue TV transmitter building in 1939. The dungeon basement contained power supplies and gloom-seeking spiders. My car sits outside.

jects far from the television technology that had brought them to Purdue. One interesting assignment that fell to me was to serve as an aide (and guard) for an important German physicist and television engineer, Dr. Kurt Schlessinger, who had been rescued by CBS as he was making his escape from Germany through France on a bicycle, carrying no more than his beloved violin. CBS lacked a secure facility in which to house him, however, so they turned him over to RCA, whose connection with Purdue provided an ex-

Figure 7.7 Some of Professor George’s tubes still hang on the lab wall, now a student lounge.

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cellent residence as well as lab facility where he could do further television research and possibly even invent other valuable warrelated technology. Schlessinger was formerly chief engineer of the Siegmund Loewe Television Company in Berlin, and my role was to keep him supplied with whatever equipment he needed and to translate and summarize his many German technical papers and inventions. He became very well known in the United States for the widely used television circuit techniques that he developed. This snapshot of Purdue’s part in the development of television will serve to explain why many of the awards, medals, and honorary degrees, received by the late Vladimir K. Zworykin have come to be displayed in the Electrical Engineering and Computer Science building on the Purdue campus.

CHAPTER

8

SARNOFF, RADIO, AND EARLY TELEVISION

A

LTHOUGH THE INTENT of this narrative is to focus on the development of the technology of television, one must remember that television was just one thread in the overall fabric of electronic development throughout the 1920s and 1930s. It was entertainment radio and music reproduction that held the public’s attention and loosened the purse strings in those days. You could already see several large American companies jockeying for dominant market positions in this newly emergent home entertainment business, and leading them was the Radio Corporation of America. RCA had been formed in 1919 at the request of the Navy Department to serve the national interest as an American-owned radio company to compete in the burgeoning field of international wireless communication. As part of this plan, the previously British-owned American Marconi Company, which had dominated the scene through World War I, was purchased principally by the General Electric Company, Westinghouse, and AT&T. A crosslicensing patent pool was worked out among them and RCA was chartered to serve this radio group as its equipment sales representative. RCA was also to operate and further develop the international wireless communication and ship-to-shore services then in existence. Owen D. Young, GE’s Chief Counsel and Chief Executive, who served as RCA’s first executive officer must have been surprised when he opened the “package” he had just bought from the Marconi group to find that it contained the young David Sarnoff, who had grown from office boy to its commercial manager. He and Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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Figure 8.1 David Sarnoff.

Sarnoff soon became close friends, Young leaning heavily on him for advice in this new field. Together they shaped the course of the company in the direction of commercial distribution of music, news, and entertainment because Sarnoff insisted that this type of public radio would be a far more profitable business than the wireless telegraph business that the company was originally chartered to attend to. By 1929, Sarnoff and Owen Young had moved RCA firmly into home radio sets and network broadcasting. They had already launched the National Broadcasting Company, and with this success behind him in a field that very few people knew anything about, Sarnoff was a giant and was handed the presidency of RCA in 1930. Not until 1933, however, was he relieved of the founding company’s oversight and set free to operate RCA as an independent company. A consent decree issued by the Justice Department in lieu of an antitrust action opened the consortium’s dominant patent pool to all potential manufacturers of radio products. In this new climate, Sarnoff arranged the purchase of the Victor Talking Machine Company, whose sales of its old and rather crude mechanical phonographs was being depressed by the appearance of the new little radio music boxes that were springing up everywhere. Soon, the world would be buying RCA Victor radio/phonograph sets bearing the famous “Nipper” trademark and playing the new RCA Victor (78 rpm) records, which had vastly improved electronically processed sounds on them. The phono-

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graph factory, in Camden, New Jersey, was perfect for building radio sets that needed handsome wooden cabinets similar to the ones that the Victor people were so skilled at building. Sarnoff now had a super factory as well as most of the patents controlling consumer electronic technology. It was natural, therefore, that the radio and television laboratories that had previously been working separately within the GE and Westinghouse organizations should converge within the new RCA Camden operation. AT&T and its Western Electric Co., the telephone group, had withdrawn from that consortium in a more or less friendly fashion sometime before. Led by William Paley, son of a wealthy cigar manufacturer, they built their own radio broadcasting network, the Columbia Broadcasting System (CBS), in 1928 and seem destined to compete with NBC forever. Sarnoff, a rather short and slightly plumpish man, was always scrupulously dressed. He wore coat and tie even in the heat of summer, and his immaculate silk suits gave him a very distinguished look. It is terribly unfair to portray Sarnoff as a greedy monster intent upon swallowing up the inventions and good ideas of lesswell-positioned private inventors or smaller organizations. He was always at great personal risk in authorizing the use of publicly derived corporate funds to pursue the uncertain development of a practical and working video delivery system. He greatly accelerated the development of television. Without him, things could have dragged on for many more years and the color system, in particular, would probably have gotten off to a very ragged start. The corporate changes described above now brought Sarnoff and Zworykin together for the first time, and upon gaining acquaintance with him, Sarnoff immediately recognized the man’s central role in the development of television. He also soon learned that Zworykin’s beautiful Kinescope display tube had not come about without arousing some patent interference cases, in particular with a French inventor by the name of Pierre Emile Louis Chevalier, who had done some very fundamental work on electrostatic focusing and on the acceleration of electron beams to make the bright pictures that Zworykin was looking for. Sarnoff took steps to quiet whatever patent interferences Zworykin had generated and purchased the Chevalier patent outright. He then im-

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posed a high degree of secrecy on all of Zworykin’s further work, holding it under wraps until it was fully operational, patented, and ready to be placed on public display. In this atmosphere, Zworykin and his Westinghouse associates met and merged with their fellow television engineers from the General Electric Company, now joined under the RCA banner. Thus began the last chapter in the development of television. Zworykin’s idea of an electronic camera tube that would incorporate charge storage to enhance its light sensitivity was embodied in his concept of the Iconoscope. Work toward that goal had progressed very slowly during the years he spent at Westinghouse, probably due to the lack of corporate enthusiasm for the whole matter of television. Now, merged with the team from GE, and with the enthusiastic backing of Sarnoff, development of the tube proceeded at a greatly accelerated rate. Figures 8.2 through 8.16, from the Zworykin’s personal photo album, illustrate the progress of those times. (Photos courtesy of the David Sarnoff Library, Princeton, NJ, and the Steven Restelli Web site, Stephen844 @JUNO.com.)

Figure 8.2 The Iconoscope, first really useable electronic camera tube.

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Figure 8.3 1933 Kinescope photo of Dr. Zworykin taken through his Iconoscope camera.

Figure 8.4 Drs. Engstrom (left) and Zworykin (right) viewed through a 1934 version of the Iconoscope.

Figure 8.5 1933 test pattern of the 240 line pictures.

Figure 8.6 First view of a famous mouse on TV.

Figure 8.7 Engineer Ray Kell plays the piano.

Figure 8.8 Other cartoon characters. 52

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Figure 8.9 The Iconoscope goes to the zoo.

Figure 8.10 Action movie.

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Figure 8.11 Leslie Flory (left) joined RCA in 1930 as a graduate of the University of Kansas. He became one of Dr. Zworykin’s most valued and talented craftsmen and engineers. He built everything from the tubes themselves to finished equipment such as the military infrared “sniper” and “snooper” scopes as well as the “creepy/peepy” miniature TV camera. He took many of these early pictures. On the right is his associate, Charles Banca. In the second picture, he is welding Iconoscope parts together. He died in 2002.

Figure 8.12 Arthur Vance was the original TV circuit design engineer. He later led the way into analog computing and was in charge of RCA’s huge postwar computer, the “Typhoon,” which was the best of the early computers that our military forces had.

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Figure 8.13 It is August 23, 1932 and they’re up on the roof! Taking the first electronic picture of a solar eclipse. Top, unknown person (left), Elmer Engtrom, and Dr. Zworykin. Middle, Gregory Ogloblinsky, left, Richard Campbell, and Dr. Zworykin. Bottom, this is what they got.

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Figure 8.14 Ray D. Kell came from the University of Illinois in 1927 and started at GE, working under Dr. E. W. F. Alexanderson on their mechanical TV scanning system. Kell was perhaps the single most important television development engineer of all. By 1940, he had already received the “Modern Pioneer Award” from the National Manufacturers Association and a great many more honors would come to him later. He is truly one of the original TV pioneers! Kell transferred to RCA in 1930, along with the other GE notables, Alda Bedford, Randall Ballard, and W. A. “Doc” Tolson. He served as the engineering group leader for color TV development all the way to the final conversion of video tape to color. He retired from RCA in 1971 and died in 1986.

Figure 8.15 Two of Dr. Zworykin’s highest-level scientists didn’t live to see the results of their pioneering efforts. Left, Dr. Gregory N. Oglobinsky was a French physisist/engineer who contributed greatly to perfecting the early Iconoscope. He was killed in a high-speed automobile accident while visiting France in 1934. Right Dr. Browder J. Thompson was a codirector of the RCA Laboratories with Zworykin at its opening in 1942. On an assignment to evaluate a proposed radar installation in Italy in 1944 a German fighter shot down the airplane that he was in.

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Figure 8.16 David Sarnoff launches the beginning of experimental black-andwhite television broadcasting in the New York area at the World’s Fair on April 2, 1939. Ten days later, President Franklin D. Roosevelt was the first president ever to be televised. The Iconoscope camera was employed.

CHAPTER

9

THE RCA LABORATORIES DIVISION

F

ROM WHAT WE’VE seen so far, it seems fair to say that by 1939 the “wheels and engine” of a great new video information vehicle had been created through the efforts of a long list of scientists epitomized by such people as Nipkow, Dieckmann, Baird, Jenkins, Zworykin, and Farnsworth. All that was needed now was fuel injection, electronic ignition, power steering and brakes, automatic transmission, air-conditioning, posh seats, lighting, a great sound system, and swank (color) styling that would attract and maintain endless public demand for the product. RCA was always a dominant force in the development of both radio and television and had almost dictatorial power over the industry through its widespread manufacture of most of the tubes and other important component parts of everything electronic. It was not without competitors, however, including General Electric, Zenith, Philco, Sylvania, Hazeltine, and DuMont. RCA was the most capable and most motivated of all to take the risk of financing the enormous development that would first inaugurate and install a high-quality monochrome television broadcasting system throughout the country and then expand it into the compatible color system that we have now enjoyed for half a century. In 1929, the just merged group of engineers at RCA’s Camden facility was originally divided in two groups: Dr. Elmer Engstrom, from GE, headed areas of work involving radio transmitters and receivers, vacuum tubes, audio systems, and theater equipment; Albert F. Murray, who was from John Hayes Hammond’s radio parts company, was set up to manage the group that included the television research people led by Zworykin. Without warning, Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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Figure 9.1 Dr. Elmer W. Engstom.

however, Murray unceremoniously defected to Philco, taking with him several of Zworykin’s best engineers who, of course, knew many of RCA’s proprietary television secrets. Briefly, RCA took this as a serious blow. Philco had just brought into its employ the highly acclaimed Philo Farnsworth, anticipating that his genius would enhance their competitive position with respect to RCA. The Philco people saw Sarnoff as having unfairly left them behind in developing the radio industry and they were determined not to let that happen again with television! Farnsworth, who was a “loner,” was certainly no miracle worker for the Philco team, however, and that association lasted for just a short time. Philco had already developed a very capable product design team on its own and they were producing outstanding products in both radio and television. They never did enter the studio equipment or broadcast transmitter end of the business, however. To smooth things over after the Murray incident, Dr. Engstrom took over management responsibility for all of RCA’s research and advanced design activities. He was an excellent administrator as well as part-time evangelical minister. He imposed a stern and quite academic discipline on the laboratory. His fair, compassionate, and quiet nature was always visible. Coming into that atmosphere at war’s end, I felt a distinct “intellectual Camelot” effect there.

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As an electrical engineer, Engstrom had already distinguished himself with major contributions to television through his careful study, which precisely defined the optical specifications that the television system must have in order to meet the requirements of the average human viewer. He reasoned that it would be of no use to provide the eye with more information than it could really use, nor should it be starved with less than it requires for comfortable viewing. By performing well-planned tests on a large group of individuals, Engstrom sorted out such fundamental factors as necessary screen brightness, image size, and resolution versus viewing distance, as well as the relationships between screen brightness, flicker rate, and eye fatigue. These are the reference standards for television pictures used to this day. Engstrom opened RCA’s magnificent electronics laboratory in Princeton, New Jersey in 1941 as its Director. There, with a staff of 125 scientists and engineers, the design of America’s compatible, monochrome and color television system would be finalized. I was fortunate to be absorbed into that group in 1945 as the Second World War ended. The laboratory possessed every possible machine tool or other fabrication device with its own skilled craftsman who was always on hand to materialize the most exotic ideas that anyone could think up. The office/labs were a comfortable size for two people.

Figure 9.2 The RCA laboratories in Princeton, New Jersey.

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There were lecture rooms and a large scientific library where we frequently sank into comfortable chairs immediately after lunch. The cafeteria served particularly scrumptious food and we were encouraged to take a break there every afternoon. Most scientists would regard this as life at its very best! There were five laboratory divisions within the Princeton building: Electronics, headed by V. K. Zworykin Tube research, headed by Irving Wolf Radio systems, headed by George Brown (H. H. Beverage) Acoustical, headed by Harry Olson Physical research, headed by L. P. Smith Zworykin, director of the electronics laboratory, more scientist than manager, was backed by Engstrom as that large group worked on anything that had to do with imaging. Even the electron microscope, which RCA was just then developing as a commercial product with the aid of Dr. James Hillier, one of its original inventors, was assigned to the electronics lab. Zworykin held that position until 1955 when he was forced into retirement at age 65 in accordance with Sarnoff’s iron-clad policy (which he later failed to apply to himself). Since the Princeton Lab was opened just as the United States was drawn into World War II, the first developments made there were necessarily related to applications of electronic technology to military needs. Television was high on that list, and the many devices made at that time were treated with extreme secrecy. At the end of the war, the public would be shown how large bombs carrying television cameras could be guided to their targets by remote control and how a new super-sensitive camera tube sensitized for infrared light (to see in the dark) made it possible for pilots to fly safely close to the ground. Later, more camera tubes were invented to meet the increasingly critical demands of ongoing civilian television applications. Upon my arrival at RCA, office/lab assignments were already getting tight so I was assigned to share one with a Mr. John Evans, who turned out to be such a remarkable individual that I must tell you about him. Educated in the public schools of Philadelphia, and with no other academic credentials than his own self-education, his natural genius qualified him to participate alongside the most respected scientists in the country in building the first high-

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power radar equipment ever made. John had a knack for making his own vacuum tubes, tubes that could produce high power at radio frequencies never before reached in the mid-1930’s. Although 300 MHz isn’t even thought of as a particularly high frequency in present times, it was the upper limit in those days, and producing it at kilowatt levels was terribly important for showing our military people that radar was going to be an extremely valuable tool for National defense in an uncertain world.* Working with Dr. Irving Wolf, one of our country’s original radar scientists, John’s transmitters could penetrate many miles, strong enough to reflect back the presence of enemy aircraft, ships, submarines, and so on. To facilitate their pioneering radar research, RCA rented space in a hangar at the Lakehurst Navel Air Station. Here, a great many moving targets for their crude radars were always available, and on May 6, 1937 a particularly large airship came into view on their display screen. It was the hydrogenfilled Hindenburg zeppelin from Germany. As it prepared to dock, the huge airship suddenly burst into flames to everyone’s great surprise and crashed to the ground, killing 36 people. John and Irving immediately thought that their high-powered radio waves had produced an arc within the airship’s bag and caused the explosion. Both of them experienced great anguish over the matter for a long time, even though reputable scientists, both then and now, have denied any possibility that such could have been the case. Recently, NASA scientists have pointed to the highly flammable coating that had been applied to the outside of the fabric covering of the airship as most likely having been ignited by a spark of static electricity thrown from the docking stake. John’s ever inventive mind and skillful fingers were particularly busy when I set up my desk across from his in 1945. At that time, he was working on electrophotography, which is a process of making pictures by electrically charging ordinary paper in the dark and selectively discharging it, as with the light image from a photo enlarger. John was producing beautiful black and white enlargements, bringing them out with carbon black powder picked up in a brush of magnetized iron filings. For all we know, RCA may have been one of the companies engaged in evaluating Chester Carlson’s 1937 invention of Xerog*This was well before the breakthrough into microwave radar (3000 MHz) that was made possible by the British invention of the cavity magnetron and its further development at MIT’s wartime Rad Lab starting in 1940. See Jennet Conant’s excellent description of that remarkable period in her book, Tuxedo Park.

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raphy, for which he was just then seeking corporate sponsorship to help him develop office photocopiers. The Haloid Corp. was the one that took Carlson on and in a short time became Xerox, the “dry writing” company, which has covered the world with copiers. Too bad RCA didn’t pick up on that one! I can also remember helping John qualify (for shipment) a large batch of far infrared light sensors that one of the Government agencies had ordered for war-time purposes. He had made each cell himself, encapsulating it within a sodium chloride dome that permitted the infrared wavelengths to enter. From the length of a long hallway in the building, I recorded the meter readings that each cell produced as John aimed a puff from his cigarette at us. There was a problem in working with John, however. He needed to keep the room in total darkness for most of the work he was doing. So there I was, sitting in the dark a large part of the day and wondering what to do about it! Before long, I found a space behind a row of equipment racks in one of the control rooms that flanked the theater-like TV demonstration studio that belonged to the color development group. I squeezed my desk into it and there it remained through my entire tenure with RCA. John’s many contributions to the development of television, from his hands-on participation in placing the antenna on top of the Empire State Building, to his design of the original UHF television broadcasting transmitters that opened up many new channels in the TV spectrum, earned for him the RCA Laboratory’s highest honor, The Award for Meritorious Research in Television. Late in 1945, there were many other leftover war-related tasks at the Lab that a newly hired and yet untried engineer would be asked to finish up. One involved inspecting a mountain of 16 mm test films that had accumulated during the television-guidedbomb project. The bombs were being released from about 8000 feet above a circular set of target rings laid out on the ground. Miniature image orthicon camera tubes (MIMO) were used to bring a televised view of a target to the remote controller. The cameras appeared to work just fine, producing excellent images of the descent to the target, the ground, and then the blackout that came so abruptly. The instability of those first missile guidance systems, however, produced dizzying images from rocking missiles, many never falling within the target’s outer ring. Much remained to be done before the present-day precision guidance system that our military now uses so effectively was achieved.

CHAPTER

10

THE EVOLUTION OF SENSITIVE CAMERA TUBES

THE ORTHICON Just prior to World War II, Zworykin’s Iconoscope had passed through a major transmutation thanks to the skillful efforts of Harley Iams and Albert Rose. The improved version of the tube had been renamed the orthiconoscope or simply orthicon (Figure 10.1). A new type of transparent target had been developed that would allow the tube to be built in a straight line with the electron gun in the rear. A transparent but electrically conducting film was deposited on the forward side of a very thin slice of insulating material, like mica, and this would serve as the signal plate. The photosensitive surface was then deposited on the inward side, which was accessible to the scanning beam. The light-sensitive film released photoelectrons in proportion to scene brightness, as usual. These were drawn away by a nearby collector ring, leaving the target surface with a (positive) charge image of the scene, free to grow between scan contacts. This construction provided for light storage just as in the earlier Iconoscope, but now, just a gentle, low-velocity scanning beam was used to scan the target and replace the image electron charges that had been lost. This reversal of the earlier Iconoscope construction was made possible by use of the transparent target. It was a good high-resolution tube and sensitive enough to be used both indoors and out. It was a big improvement over the original Iconoscope, but it had an instability problem. Whenever sudden flashes of bright light entered the scene, as might come from a photographer’s flashbulb, the photocathode became overcharged to a point beyond the ability of the scanning beam to remove the Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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Focusing coil Cathode

Signal output

Deflection coil Return beam

Target

Scanning be am

Focusing electrode

Decelerating electrode

Figure 10.1 Cross section through the orthicon.

charge immediately. This produced the appearance of a large drop of water evaporating slowly over part of the picture as the excess charge was dissipated. As the war years began, it was urgent that this problem be overcome, and in making that effort, an entirely new tube, the image-orthicon, was born.

THE IMAGE-ORTHICON* The image-orthicon was developed during World War II for military purposes. It was based on the design of a new, two-sided, conductive thin glass target that Albert Rose had proposed earlier and had already tested. It offered a way of correcting the instability of the orthicon as well as the possibility of higher sensitivity. In the final form of the image-orthicon, electrons from the photosensitive cathode on the inside face of the tube were accelerated along axial magnetic lines (produced by a DC solenoid electromagnet enveloping the tube, see Figures 10.2 and 10.3)* to strike the glass target structure. The complete target structure in*This section was written by Paul Weimer (2003). *It should be noted that a DC solenoid electromagnet is used to envelope all inline tube constructions, serving as it does to maintain the focus of electron streams moving along the axis of a tube. Both scanning beams as well as photoelectron images formed at a photosensor are served. Since this mechanism was first required to create the image-dissector-type tube, Philo Farnsworth obtained an early patent on the effect. RCA and other manufacturers were, therefore, obliged to obtain a license under his patent in order to produce the later sensitive types of camera tubes described here, which Farnsworth himself had no part in developing.

THE EVOLUTION OF SENSITIVE CAMERA TUBES

Cathode (zero)

Peruader (+200 V) Secondary electrons

67

Focusing cell Deflection yoke

Secondary electrons Electron image

Return beam

A (+200 V) Signal output electrode (+1500 V)

Scanning beam

Wall costing (+180 V) Photocathode (–300 V) Target screen (zero)

Alignment cell

Decelerating ring (zero)

Two-sided target glass

Figure 10.2 Cross-section through the image orthicon.

cluded a fine-mesh screen mounted very close to the glass target on the side facing the photocathode but not touching the target. The fine-mesh screen served to capture the secondary electrons knocked out of the glass by the photoelectrons that struck the glass with an energy of several hundred volts. By adjusting the voltage on the fine-mesh screen, the voltage on both sides of the conductive glass could be controlled. In the bright areas of the scene, of course, the greater density of electrons would have the capability for driving the glass target more positive than elsewhere. In what has been described so far, no picture signal has been generated. To complete the tube, an electron gun is needed to discharge the scanned side of the target glass with a low-velocity scanning beam that returns the glass to its dark potential. This is accomplished by setting the potential of the gun cathode to a proper (low) value, and using adequate beam current to discharge the brightest parts of the picture. That fraction of the scanning beam that is not needed to discharge the target in the darker areas returns to the electron gun as a modulated video signal, which is then introduced into an electron multiplier surrounding the gun (video out).

Figure 10.3 The Famous RCA image-orthicon television camera tube.

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To our great satisfaction, the gain from the multiplier combined with a modest gain from the photocathode and target gave us the most sensitive television camera tube that had ever been made. It was the first man-made sensor to match the human eye in sensitivity. The image-orthicon was much more difficult to build than the original orthicon had been, however. The construction of the target structure, which had to be baked at high temperatures without damage to the complex structure, was a major problem. Another problem was making the low-velocity scanning beam land uniformly along the edges of the target. Near the end of the photoemissive camera tube era, RCA made one more tube that used the same target structure as the image-orthicon, but achieved more sensitivity and a higher-quality image. It was called the image-isocon. It inverted the polarity of the output signal (converting beam noise to black) by allowing only the scattered portion of the scanning beam to be fed into the multiplier, thus obtaining a signal having a better signal-to-noise ratio, which translated into higher tube sensitivity. By the time the image-orthicon was no longer available, RCA continued to manufacture the isocon for applications requiring this ultimate tube sensitivity. In spite of the dominance that the image-orthicon held over the television industry from the moment of its birth, RCA developed one more pickup tube in this period. The “vidicon,” as it

Figure 10.4 Creators of the image-orthicon, Dr. Albert Rose. Dr. Paul Weimer, and Dr. Harold Law, deserve great credit for their accomplishment.

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Figure 10.5 Dr. Paul Weimer.

was named, played such an important part in furthering the development of television technology that it too must be put on record.

THE VIDICON The vidicon was the first pickup tube to break away from the principle of emission of electron charges from a photosensitive cathode. It is based upon the change in electrical conductivity of certain materials when illuminated. The original discovery of an interaction between light and anything electrical was first observed in the photoconductive property of the metal selenium. The effect was noticed in early batteries that were being used to power telegraph systems in the late 1800s. It was observed that the batteries acted differently when sunlight fell upon them, and measurements showed that the electrical resistance of the selenium metal decreased markedly in the presence of strong light. Weak light produced proportionately smaller changes in resistivity. Response to sudden changes in illumination was not immediate, however, the effect being rather sluggish. For this reason, little thought was ever given to using photoconductivity as a light sensor for such fast-moving events as that of picture scanning. Miller and Strange in England as well as Knoll and Schroeter in Germany made serious attempts to overcome this basic sluggish characteris-

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Figure 10.6 The first vidicon camera chain.

tic during the 1930s but were unsuccessful. Work on video pickup tubes in the early years, therefore, continued only on the principle of photoemission as used in the iconoscope, the orthicon, and Farnsworth’s image dissector. As World War II approached, there was a great demand for light-sensing apparatus, particularly compact and rugged infrared light (IR) sensors. Again, the superior light sensitivity and other attractive properties of photoconductivity brought it back for review. This time, the laboratories that examined it were far more advanced and better equipped to identify and processes useful materials. Furthermore, infrared sensing and signaling devices had now become such a military necessity that huge sums were being spent to study and improve every form of it. Under these conditions, the work was quite successful and provided the basis for the development of a number of important new military instruments. As familiarity with photoconductive material and techniques grew, ideas for making camera tubes with it returned. Since RCA had been one of the leading research centers for the development of IR equipment and was the manufacturer of the famous “snooper” and “sniper” night sighting equipment used during World War II, further exploration of photoconductive technology held a high priority at the Laboratories. Dr. Zworykin (Figure 10.7), who had been so involved in the

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Figure 10.7 Dr. Zworykin seems pleased with the vidicon camera.

science that had made television broadcasting possible, seemed to have been offended by the gross use he saw being made of it. He probably expected that the product of so much intellectual effort over so many years would be greeted with a more fitting dignity and would immediately find its place in uplifting humanity and propelling the finer things of life into vulgar homes. Educationally starved and uncouth masses could be given inspiring examples of noble conduct and an aspiration for creativity in every field. The programming that he saw falling into place, however, was almost the opposite of this, with emphasis placed on childish show-off games and inducement to purchase self-indulgent products. He often said that the most important control on his own television set was the off switch. He foresaw the enormous use that could be made of closedcircuit forms of television if smaller, more rugged, and less complicated and costly equipment could be developed, and he was in the right place to do something about that! Thus, encouraged by Zworykin, camera tube work moved away from miniaturizing the still highly complex and expensive image-orthicon tube and toward the evolution of a much simpler photoconductive device. In 1947 Albert Rose, Richard Bube, Roland Smith, and some others began fundamental studies on the physics of photoconductivity. Concurrently, Paul Weimer and his colleagues Stanley Forgue and Robert Goodrich began experimenting with photocon-

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ductive image targets and by mid-1948 they were producing very promising targets. A little later, when good-looking sealed-off tubes were becoming available, I tried to call them “photocons” but that name didn’t stick because of some prior use of the word. The tube finally became known as the “vidicon,” and about that time Zworykin asked me to build a tiny (for those days) camera around them. The vidicon has many of the good qualities of the image-orthicon in terms of light sensitivity and resolution, even though the tube is many times less complex and far less costly in its construction. However, since the image-orthicon was still the star and a major profit maker for RCA, it was necessary to give the vidicon second billing in a noncompetitive, off-street play entitled “Industrial Television.” As soon as production quantities of vidicon cameras became available, they found immediate use in everything from surveillance to classroom microscope magnifiers and for just about everything else that human beings use cameras for. Wherever there is something that needs to be seen in places too hazardous, too uncomfortable, or unreachable, the vidicon camera found immediate application. It was a natural for underwater rescue equipment and such things as the inspection of sewer pipes. Some of the first cameras were welcomed in the Holland Tunnel to assist with traffic control, but at Sing Sing prison they met immediate resistance when placed there for general surveillance. The military could think of hundreds more places where they needed small television cameras, all the way from controlling the flight of a drone airplane to sending pictures back from outer space. It wasn’t long before we were actually looking down on our own earth and its weather patterns from satellite-mounted vidicon cameras. It is notable that it was a vidicon camera that gave us that intimate view of the first human foot that was placed on the moon, by Neil Armstrong in 1969. When the vidicon camera was ready to be promoted for industrial applications in 1949, Zworykin and I were invited to lunch with the RCA board of directors in Sarnoff’s prestigious private dining room atop the RCA building. After lunch, Zworykin explained the important features of the new tube while I panned the little camera over the group and onto the New York skyline, much to the board’s enthusiastic approval. As it turned out, RCA was not the only company in the world studying photoconductive television camera tubes. A few years

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after the vidicon had become a common electronic component, Phillips of Eindhoven, The Netherlands, developed a very clever manufacturing technology that produced better (vidicon) targets than RCA was making. Their research had brought them to a type of target that so dramatically reduced target capacitance that lead oxide could be used in the light sensing film, which increased the tube’s sensitivity by a very large factor. Their tube was introduced in 1962 as the “plumbicon” because of its use of lead. In a 1⅓ inch size, it had equal or greater light sensitivity and resolution than a 3 inch image orthicon while producing video with a better signalto-noise ratio, particularly in red. This plus the fact that the tube has no front-end image section to be bothered with in registering color cameras, helped the plumbicon quickly become the replacement for image-orthicons in all three-tube color cameras. RCA’s once spectacular image-orthicon was rendered obsolete almost immediately by Philip’s simple new version of the vidicon. From 1962 on, all tricolor cameras were built around plumbicons. In our present times, of course, the plumbicons, too, are gone, displaced in this impetuous digital age with a small chargecoupled, solid state light sensor array that can meet and exceed the performance of any vacuum tube—and has no color registration problems at all! Construction and Operation of the Vidicon The following intimate details of the vidicon’s construction and operation will serve to preserve for us the memory of the original art of vacuum tube electronic science. A well-focused scanning beam from an electron gun is placed a few inches behind a thin photoresistive film that has been evaporated over a transparent but conductive film on the back of an image faceplate. The beam acts to bring each point of contact to some reference potential (like zero volts). All points on the front side of the film (lighted side) are connected in common to a sealed-in Kovar metal ring, which is held at a few volts positive through a resistor. After every scan, each pixel-size capacitor comprising the front-to-back surface of that small section of film, defined by the beam, is left fully charged to the value of the target voltage. In the dark, the resistivity of the photoconductive film layer is so high that virtually no discharge of those tiny capacitors takes place. Where light falls upon them, however, the conductiv-

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ity of the film increases (resistivity falls) and a discharge of each capacitor element takes place in proportion to the light intensity reaching it (Figure 10.8). When these tiny pixel-size capacitors are again recharged on contact with the next arriving scanning beam, small impulses of charging current flow through the target resistor, producing a voltage drop across it that becomes the outgoing video signal. Since the scanning electron beam reaches each point on the target film only once every 1/30th of a second (for standard television), a considerable discharge of each point in the scene can take place between scans. This discharge effect is the light-storage mechanism of the tube and it magnifies the available electrical signal enormously, placing it well above the amplifier noise level. The video signal could be as much as a quarter of a volt. If the capacitance of the light-sensing layer should be too large, however, the brief time available for the scanning beam to recharge each pixel might not be enough to obtain a full recharge. In this case, the target layer would retain a portion of the previous picture information and carry it over to the next scan. This results in the appearance of a ghost trail of moving objects and is the first of two shortcomings that the tube has. The second is target burn, which occurs when a camera is allowed to stare at a fixed scene for a long period of time. Upon panning to another

Alignment coil Focusing coil 300 V

Deflection yoke gun 4500 V

Scanning beam Photoconductive wall +300 V target

Wall screen

Light from scene Transparent signal plate

Gun cathode 0 volts

10–30 V+ Video signal

Figure 10.8 Cross section through the vidicon.

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scene, the burned-in image of the former can remain for a long time and might even be permanent. A Comment from Paul Weimer I made the first operable vidicons at the RCA Laboratories in 1947 using a thin film of amorphous selenium as the photoconductor. However, after a few weeks, the deposited layer of selenium was found to be converting to a more conducting form of selenium, making the sensor unusable. Later a photoconductive layer of Sb2S3, deposited in a porous form by evaporation in a poor vacuum by Stanley Forgue and R. R. Goodrich, was found to be sensitive and stable. This type of vidicon was then sold by RCA for many years for use in cameras designed for industrial applications. Approximately 20 years later, Philips of Eindhoven introduced a high-performance photoconductive lead oxide sensor (the plumbicon) which soon began to displace the image-orthicon for television.

CHAPTER

11

THE FIELD-SEQUENTIAL COLOR INCIDENT

W

HAT SHOULD HAVE been a quiet, low-pressure R&D effort to allow the country’s excellent and well-established monochrome television system to evolve into a color system turned into a pell-mell scramble when the Columbia Broadcasting System, following its Hungarian-born chief engineer, Dr. Peter Goldmark, demanded a reappraisal of the standards for the U.S. television system. “Don’t settle for black-and-white television” was the cry CBS put in the streets, “because we have color television ready for you.” But was their system really ready? Could the color system they embraced ever be brought up to a level of commercial performance? Late in 1945, RCA reactivated the color research activity that had begun in 1940. At the new Princeton laboratory, the original engineers, led by Ray D. Kell, dusted off as much of the prewar color equipment as could be recovered and began reviewing their earlier work. They would evaluate every imaginable way of producing television images in color. The “field-sequential” method, now being touted so loudly by CBS, was well known to the RCA group as they had experimented with it seriously before the war and patented many of its features. It was a very attractive method of producing color, if for no other reason than its simplicity. If you could suppress the inherent mechanical disturbances that came with the rotating color wheel, the wind, the motor noise, and the vibrations caused by imbalance, by placing everything in a sound-tight box having a thick lens over the CRT window, the effect was spectacular! This was the first time people had ever seen anything but monochrome TV, and here was a perfect Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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jewel of a television picture in color. It had deep vibrant color tones, every bit as good as the then-current Technicolor motion pictures. No wonder so many casual observers ran into the streets joining the cry, “color television is here.” Not so, really, because so many of its problems were being overlooked during those early euphoric moments. Here are some of them: 1. Whenever motion took place in a scene, there was inevitable color breakup. A worst-case example of this was a tennis match in which the moving white ball would cross the screen as a sequence of bright red, green, and blue balls. A person waving a hand rapidly would gain a fist full of colored hands. This fundamental problem had no solution. 2. The demonstration sites where viewers were taken (in) were always furnished with a direct, unlimited bandwidth, coaxial cable connection to the studio camera so no one ever saw what those pictures were going to look like when they would ultimately be broadcast through a 6 MHz radio channel regulated by the FCC. Furthermore, the sites were rather dimly lighted so that the ambient room light would not wash out the quite dim color display. After all, the only light available to form the picture came from a single white screen CRT viewed through color filters that blocked out two-thirds of its light to get the color effect. Furthermore, the color filters themselves were no more than 30% efficient, making only about 10% of the originating light available to reach the eye. 3. If the pictures could have been brighter, an enormous amount of flicker would have been noticed at the low refresh rate (frame rate) that was used to keep the video bandwidth anywhere near the established 6 MHz transmission channels. Picture resolution was down way below 300 lines and Peter Goldmark was grasping at straws when he introduced his “crisping” circuit to try to improve it. His circuit simply increased highfrequency gain (and noise) in the receiver to give the illusion of a slightly wider video passband. 4. The rotating color filter wheel always inserted its presence. Small pieces of dirt or blemishes on the filters were visible as a “dirty window” effect after the initial favorable impression of the picture had worn off and the viewer grew more critical. Another disagreeable feature of those pictures was the narrow viewing angle that limited the number of viewers that could

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comfortably see into the box! It was all so new and the color images were so glamorous and eye catching that these inconveniences seemed excusable to many viewers. Assigned to work in the color group as a young engineer in 1945, I was as impressed as anyone with the beautiful color images that were being generated with just a single-tube camera equipped with a rotating color filter disk. The receiver was simple as well, producing a sequence of red, green, and blue, color images seen through a synchronously rotating color wheel placed in front of an ordinary white-screen CRT. It was amazing how the eye could fuse them into a somewhat flickery but otherwise goodlooking color image. The RCA color group had studied this attractive technique long enough before the wartime interruption to have practically worn out their old orthicon camera (Figure 11.1) so the first assignment I had at RCA was to build a fresh new field sequential color camera using the new image-orthicon, which was a much better camera tube. The logic of this simple approach to color still appealed to almost everyone in RCA and we tried vigorously to make it work, but we never did. We were searching for ways to make the field-sequential process produce larger, brighter, more flicker-free pictures, and to eliminate the pesky rotating color filter wheels. In the course of the work, we placed a large CRT tube (12 inch) inside a rotating

Figure 11.1 RCA’s prewar experimental field-sequential color camera.

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drum that carried red, green, and blue color filter sheets on it’s surface. Running at a speed of 180 color fields per second, this configuration produced an almost flicker-free color picture of quite good quality. It would have required a 13 MHz frequency channel to broadcast it on radio, however, more than two standard TV channels. That drum display and the new camera made the best color pictures we had ever seen and it gave us the inspiration to have a little fun and try to make a three-dimensional color display out of it. We did this by superimposing patches of Dr. Land’s new polarizing film over the color filters on the surface of the drum in alternating quadrature positions. Thus, a viewer fitted with polarizing glasses set to the left eye for one polarization and the right eye for the other, would see alternating color images. The camera also had to be fitted with a polarizing light splitter, giving it left and right eye views of the scene. This complex arrangement worked surprisingly well and gave a room full of people wearing special glasses a very spectacular stereopticon color demonstration; it was considered to be a look into the future of television (Figure 11.2). Our three-dimensional color television experiment was so interesting that RCA gave a number of public showings of it during

Figure 11.2 Front and back views of the drum receiver used in the threedimensional demonstration.

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several weeks in December of 1945. During one showing, a wellendowed young lady was seen perched upon a stool holding a barber-pole colored stick. Whenever she thrust that stick toward the camera, a room full of viewers would all duck away! In order to make up sets of the polarized viewing glasses, we sent a couple of our engineers over to Princeton to raid the drug stores of their leftover sunglasses for their frames. Upon entering a store, the shopkeepers were already suspect at the mention of sunglasses in a New Jersey winter, but when the engineers started popping the lenses out to see if the frames would accept the Polaroid material, arms were thrown in the air and comments were made about “those RCA crazies are here again!”

Figure 11.3 This demonstration studio was a very important place throughout the development of color television. It had a theater-size screen at one end and could seat more than a hundred people in deck chairs. David Sarnoff brought important guests here frequently. This is where he was shown the famous “three tail dragon” tube that really launched the development of RCA’s simultaneous color television system in 1946. Al Schroeder (left) trains the original field-sequential color camera on Dr. Gordon Fredendal and technician Frank Howarth (1945).

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Even though that colorful and entertaining field-sequential color system was fun to play with, we could all see that the dim, flickering, low-resolution pictures, completely incompatible with the already established monochrome television system, could never become a commercial success. Why couldn’t CBS see that? Those people pressed on and on with it, even persuading the FCC to approve it as the U.S. standard in 1950! That was a decision that proved to be a huge mistake and the FCC was ultimately forced to withdraw it in 1953. By that time, RCA’s highly sophisticated and completely compatible color system, reinforced by contributions from other parts of the television industry through the National Television System Committee (NTSC), was finally ready for commercial use. Curiously, RCA was much criticized for not being willing to fall into step with CBS over color in those early days, and their conflicting ideas have often been described as a “Color Television War.” That wasn’t it at all! The RCA engineers had given the fieldsequential system a very thorough testing and concluded that it had insurmountable limitations that simply prevented it from ever reaching a quality level suitable for commercial broadcasting. This was immediately borne out when the FCC allowed CBS to try to put their system into operation. As you will see, there was a better way to produce color pictures than to spin color filters in front of a white CRT screen, but it took us quite a while to find it. Many were the critics who discouraged us from even bothering to look for it! When it was finally found, it came with an enormous side benefit; namely, it ran on the same size railroad tracks as black and white television or, in other words, it was compatible with the existing monochrome system standards and simply added the color feature to it.

CHAPTER

12

THE INVENTION OF COMPATIBLE COLOR

T

HE PRODUCTION OF television pictures in full blazing color was an elusive goal for a long time and shared one natural problem with the printing industry—the registration of superposed color separation images. The theory of tricolor vision, tracing as far back as Newton, was well known and color printing by the subtractive color method had been practiced for a long time. Starting with a white sheet of paper, the primary color components are subtracted from the white of the paper by selective masking by the pigments. The subtractive color primaries are therefore yellow, cyan and magenta. Starting with a dark television screen, however, components of colored light are added to the black screen to produce colored images. In this case, the color primaries are red, green and blue, their sum producing white light. Red light plus green light produces yellow. Green light plus blue light produces cyan. Blue light plus red light produces magenta. Many of us can remember reading the color comics and popular cartoon books whose brightly colored pictures attracted young buyers. There we saw poorly registered color printing with its annoying colored edges emphasizing the misfit of the images laid upon each other. This was the inevitable effect of low-cost, multilayered color printing. At the other extreme, in the expensive “slick” magazines, one could see high-quality color printing done so perfectly that scarcely any misregistration was visible. Those beautiful magazine pictures were an inspiration to television engineers and made us wonder if we would ever be able to achieve such perfect image registration. The printing presses had the great advantage of working with solid metal printing plates for each Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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color, a base material that could be relied upon to hold its size and position. In television, we had only delicate electron beams to deal with, which were so ephemeral that we doubted we could ever get them to match up and stay put on the face of a cathode ray tube. Also, the early CRTs had many construction irregularities since they were practically hand made in small batches. Furthermore, the electromagnetic deflection coils that scanned the tubes were still very crude. Camera tubes and their deflection components presented an even worse problem because they used low-velocity scanning beams, which are extremely sensitive to every kind of magnetic influence. Even rotation of a camera in the earth’s magnetic field could cause misregistration of image components. It is easy to see why no one was bold enough to suggest the superposition of three camera tubes to pick up live color pictures at that time. A solution to the color registration problem was unknown to all of us and it was the main reason that so much time was spent exploring the field-sequential method of making color TV pictures. In the field-sequential system, all three color components travel through a single video channel, ending up producing a picture on just one black-and-white cathode ray screen. Every color gets the same treatment so no color registration problem occurs because any distortion that might happen along the way applies equally to all three color components. Pictures might be geometrically distorted, but they could never be out of registration. There was just one engineer in our group who simply refused to be discouraged about registering color pictures. Despite much early criticism and delay of his plan, Al Schroeder was finally given the resources of the tube lab to build an experimental tube. The tube he wanted built had three electron gun necks merged on an axis with the center of a standard white-phosphor CRT screen a few inches beyond their conjunction. It is easy to see why the tube was immediately dubbed Schroeder’s “three-tailed monster.” Since the guns angled away from the axis of the tube, a deflection coil could not be slid into position over them and had to be assembled piece by piece over the joined necks of the tube (Figure 12.1). The plan was to modulate the guns with color-separated video signals—red, green, and blue—which we hoped would appear as three small black-and-white pictures positioned equilaterally on the screen. Appropriate pieces of color filter material would then be taped over the image patches to form three inde-

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Figure 12.1 Schroeder’s simultaneous color television projector.

pendent color images on the faceplate. A prismatic optical system would merge the three images in superposition during projection onto a viewing screen. Sure enough, three bright little pictures showed up on that faceplate! They were fairly well focused and appeared to be geometrically identical. We taped the color filters over them and stood by as the images were merged optically to travel through the projection lens. A sheet of white paper served as a screen. After much adjusting, we found ourselves looking at a clear, steady, flicker-free, color picture in complete silence! It wasn’t very bright and not perfectly registered, but Al’s experiment showed beyond any doubt that three electron beams arriving simultaneously at a screen could be brought into registration and would stay that way. The first picture we saw was of a large red and green parrot with blue and yellow markings. This steady, flicker-free color picture was running “compatibly” on monochrome TV standards! No rotating color wheels were involved, and everything was done within one small tube. The experiment was set up in the big studio demonstration room I have described, and it looked so good to all of us that we asked to have it called it to the attention of David Sarnoff. Both Zworykin and Dr. Engstrom were obviously impressed with the experiment and expedited the visit of Sarnoff, which took place on a day in late October of 1946. This was an important day for color television.

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Sarnoff came alone this time and examined the crude lab experiment very carefully. He asked to see all the color slides we had available, gazing at each one intently. Slowly, he drew himself up, slapped his thigh, and said, “this is it, let’s go!” We had reached a turning point in the development of color television. There would be no further work done on field-sequential color systems by RCA. A press report on “compatible color television” and its benefits for the industry was immediately released (Figure 12.2), but that announcement aroused exactly no public interest or press reaction. Sarnoff now directed us to proceed with everything we could do to build upon and improve Schroeder’s new concept. The first thing we did was set up three small-diameter projection tubes, each having its own lens and appropriately colored phosphor, red, green, and blue. The tubes were focused by projection onto a 2 foot diagonal screen and we now began the experience of registering independent tube and deflection coil assemblies. Surprisingly, this turned out to be much easier than we had expected, probably due to the more uniform CRTs and deflection coils that were now in production. As our confidence grew, our displays came closer to perfect registration with each generation. Some years later, the word registration (or image registration) as had been defined by the printing industry was translated into convergence as is now universally used in television and computer display equipment. In order to get a perfectly registered source of video signals for our continuing experiments, we fell back upon an invention from the early days of mechanical television, when a flying spot of light coming through a Nipkow disk was used to scan a live scene. It took an arc lamp behind the disk to put enough light onto a darkened theater stage to get a signal from a photocell gathering whatever light might be reflected into it from each point where the scanning spot landed. Following this concept, we built a modern electronic “flying spot scanner” using a small but very bright and well-focused CRT having a white phosphor of very short persistence. The tube was swept at the standard monochrome TV rate and its uniform scanning field of white light was focused through a lens onto a Kodachrome slide in a dark chamber. Light collected behind the slide (now modulated by the color and brightness of each point in the scene) was picked up by a triplex set of photocells covered with red, green, and blue color filters. We could now rely upon perfect registry from this three-color signal source. The

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Figure 12.2 This was RCA’s first public announcement, in 1946, of a new method of producing color television pictures using standards compatible with the existing black-and-white television broadcasting system. This public announcement received virtually no press attention at all.

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flying-spot scanner system worked so well that the technique was soon advanced to include scanning 16 mm motion picture films with it. Using the flying-spot image source, all three of the color components of a (slide) scene could now be displayed simultaneously using three separate projection tubes (Figure 12.3). This immediately produced a threefold increase in screen brightness over anything we had ever seen before. Actually, it was more like a tenfold increase because each projection tube now had its own red-, green-, or blue-colored phosphor screen. This eliminated the losses previously viewing a white tube through a sequence of three color filters, each being no more than roughly 30% efficient. To top it all off, the scanning standards for each of the color images was identical to those of the fast-growing monochrome TV world. Color and black and white TV had been merged and henceforth would be completely “compatible.” All further work that RCA would do on field-sequential television was ended forever and serious consideration was even being given to making an attempt to bring three image-orthicon tubes into register to provide a live studio color camera. I was shortly dispatched to make that attempt.

Figure 12.3 Ray Kell adjusts focus on the first simultaneous color TV projector.

CHAPTER

13

THE SHADOW MASK PICTURE TUBES

A

L SCHROEDER (Figure 13.1) is a soft-spoken, gentle giant type of man. Well over six feet, two hundred pounds at least, with dark hair topping a brilliant mind. His role in our group always seemed to me to be that of a roving trouble shooter because, except for the picture tubes he spontaneously thought up on his own, he seldom tied himself to any one particular project or took an assignment to develop a particular thing. He was interested in everything that took place in the lab and gave all of it a serious and constructive boost. He was always available to trim up a camera or demonstrate an Iconoscope or some other display device at its very best when visitors (such as Sarnoff) were around. I always enjoyed his taking an interest in something I was working on because he always left me feeling better about it than I had before. Like several others at the Lab, he lived with his family in the pleasant little “intentional” community of Bryn Gwelled Homesteads, Pennsylvania, a short railroad commute from Princeton. Not until I was writing this book did he tell me that when he finished his MSEE degree program at MIT he had several job offers, including one from Philo Farnsworth, which he accepted. He thought that he might advance more rapidly in Farnsworth’s small company than in the great RCA, which had also made him an offer. His employment with Farnsworth lasted for only two weeks, however, for two reasons. First he examined the image dissector tube that Philo seemed wedded to and saw that it had no possible means of incorporating light storage to enhance its light sensitivity, which would doom the tube. Second, at the beginning of the third week he was notified that there had been a “company reorgaTele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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Figure 13.1 Al Schoeder.

nization” over the weekend that required all recent new hires to be dropped from the payroll. He was quite happy about that and simply went over to RCA and checked in. Encouraged by the success of his “three-neck monster” tube, he was soon doubled up over his desk day after day with a huge sheet of paper and a long straight edge, drawing electron trajectories. He had thought up another tube, one that would have three guns in the same enclosure. The guns would be set slightly off axis, aiming at a common point on the screen from their equilateral positions. In this way, the three electron beams would fall specifically upon tiny colored phosphor dots, or perhaps small glass pyramids that might be formed on the backside of a flat glass viewing screen. He envisioned that the electron beams, each modulated by its own color video, would reach the screen as directed by a common magnetic deflection coil system and thus produce a perfectly registered color image on the faceplate. To avoid any confusion that might occur where the three beams came to land on the screen, he planned to cover the phosphor dots with a perforated metal screen that would mask any unintended targets from errant electrons. This would assure that electrons from the red gun would fall only upon red phosphor dots, green gun electrons on green phosphor, and so on. As little known as Al Schroeder is to this day, he is without doubt the father of the shadow mask color kinescope which is

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probably the most important single development in color television history. Millions of the tubes have been manufactured and almost every person on the planet has come to view one daily. He filed a patent on the idea of the tube on February 24, 1947 (Figure 13.2) and it was issued on May 6, 1952. Nothing was done to actually build an experimental version of his tube, however, until the display tube panic occurred in 1949 and the lab was turned upside down attempting to build one of the tubes. To understand this last remark, we need to jump ahead a couple of years to when the FCC called RCA to demonstrate and compare its entirely electronic and compatible color system with the mechanical field-sequential color system that CBS was pressing the FCC to standardize as the nation’s official television system. RCA was far from ready to do this from several points of view but was forced into doing it anyway. The only display devices that RCA had available to show their compatible color system plan at that time were either the clumsy triniscope assemblies or the dim three-color projectors of the day. All of the receiving sets RCA brought to those 1949/50 color hearings suffered from a great many defects and none of them brought any praise to the company. Elmer Engstrom was quite embarrassed by the poor showing RCA had made with its awkward displays and he was desperately determined to develop a really good color display tube. Nearly two years had passed since Al Schroeder had taken us out of the field-sequential era with his “three-neck monster” tube, but his plan for a “shadow mask” type color kinescope had still never been built. At this embarrassing moment, Engstrom now ordered an all out, company wide, around the clock, crash program to make the tube. Never had so many skilled people ever cooperated so well and so quickly to produce a working model of a terribly complex electronic device! Schroeder’s tube came alive in less than six months! It was the resources of Dr. Herald’s well-prepared tube laboratory that made it possible to activate a team of highly skilled chemists, physicists, metallurgists, mechanical engineers, and glass blowers, to execute one of the most brilliant breakthroughs in the history of electronics technology (Figure 13.3). Two physicists, Drs. Harold and Russ Law (not relatives) took over the actual construction of the tube and added so many of their own good ideas and novel techniques that they have come to

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Figure 13.2 Al Schroeder’s shadow mask patent.

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Figure 13.3 Builders of the first shadow mask color kinescope in 1950: Drs. Harold Law, Ed Herold, and Russ Law.

be regarded as the inventors of the tube. With all due respect to the many contributions that they made to the tube, for which they deserve enormous credit, we should not allow the tube’s intellectual father, Al Schroeder, to disappear in the dust from that explosive event. The viewing screen of the first tube was built on a rounded 8½ by 11½ inch piece of flat glass. The centers of tiny triangular clusters of color phosphor dots were positioned to register just below holes in an etched metal “shadow mask,” held in position over them by supporting pins. This screen assembly was then mounted just inside the curved glass face plate of a large-neck version of one of RCA’s current 15 inch cathode ray tubes. Although the screen was visibly inside the glass, like a ship in a bottle, its beautifully bright colors and general visibility were in no way affected. This is the type of tube that was used in RCA’s first production models of their home color TV receiver, the CT100. The new tube was hard to make and expensive because of the two-part viewing screen assembly, and everyone knew that there was room for improvement, but fresh from its conquest, the RCA team was not much moved to make hasty changes.

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As it turned out, shortly before those Washington color hearings took place in 1949, one of Ed Herold’s top tube designers, Norman Fyler, was persuaded to leave RCA and join a Massachusetts-based vacuum tube manufacturer, the Hytron Electronics Company. There, soon after the Schroeder shadow mask tube became known, Norm and his Hytron colleague, W. E. Rowe, were inspired to make a significant improvement in it. In 1953, they announced the invention of a method of attaching the phosphor dots of Schroeder’s tube directly onto the inside of the tube’s spherically curved faceplate. They had found a means of mounting a curved metal shadow mask precisely in register with the dots. This moved the color screen up to where it really belongs, directly on the inside surface of the faceplate. The visibility of the picture was greatly improved by this and at the same time the cost of construction was lowered. It is understandable why RCA would be willing to pay a million dollars for a license to practice that invention, even though Hytron was, of all things, a subsidiary of that old arch rival, the Columbia Broadcasting System! From that point on, the Fyler-style faceplate became the standard for all shadow mask color kinescopes except for the more recent Sony Trinitron, where the faceplate was changed from a spherical to a cylindrical section and color phosphor stripes (rather than dots) stand vertically under a slotted shadow mask that is registered to focus the electron beams onto them. These are somewhat brighter tubes. Sadly, none of the color tubes are likely to survive long into the twenty-first century in view of the success of the recent flat panel display techniques, which, stimulated by the needs of small personal computers and TV’s, are already beginning to take over.

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HE SUCCESS OF the original, small three-tube color projector inspired the construction of a large, theater-size projector in mid 1947. The new one would fill a 7.5 by 10 foot screen in the lab’s color demonstration studio. This display, soon dubbed the three-eyed monster, was the most powerful display we ever made at the Princeton lab and its importance in the development of color television can never be overemphasized. Dr. David Epstein (Figure 14.1), pioneer in CRT design, created the first-of-a-kind, 8 inch diameter high brightness projection tubes for it. These were mounted in large Schmidt-reflector-type optical projection barrels arranged in a triangular pattern. Dr. H. W. Leverenz (Figure 14.2), RCA’s long unsung guru of phosphor chemistry, made the tough, new highbrightness phosphors in the red, green, and blue primary colors. The tubes had to be made in near-production quantities since, at the power level at which we ran them, they “browned” out in just a few hours of operation. To make them extra bright, the tubes were run with an unprecedented 75,000 volts on their accelerating electrodes. This required a large Westinghouse X-ray type DC power supply that closely resembled a coffin, which encouraged caution as we dealt with it! It is also quite possible that we, along with an innocent audience, were being generously sprayed with X-rays since governmental control of radiation exposures like this had not yet caught up with us. Randall Ballard, Al Schroeder, and Carl Wendt built the highpowered sweep and convergence circuits that were necessary to move the three 75,000 volt electron beams in unison. Since the Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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Figure 14.1 Dr. David W. Epstein, who directed development of the RCA television receiver–projector, operating the equipment that produced color TV pictures on theatre screens.

signals from our flying-spot scanner were always perfectly converged, any misconvergence seen on the screen would have to be generated within the projector itself, so Carl was generally on hand to make these corrections. David Sarnoff was always eager to show off the new projector (Figure 14.3) and brought in many world figures to see it. On a particularly hot summer day in 1948, a stellar scientific group that included the famous British radar scientist, Sir Robert WatsonWatt, came in. There was no air-conditioning in those days, so Sarnoff pulled off his immaculate silk jacket and invited his guests to do the same. He hadn’t counted on the embarrassment this would cause Sir Robert who, it was soon disclosed, was wearing a large set of red suspenders. In the darkened room he slipped

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Figure 14.2 Dr. H. W. Leverenz, director of the physical research laboratory was an industry leader in the scientific study of solid-state materials. He created the heavy-duty color phosphors for the projector.

Figure 14.3 Carl Wendt and Al Schroeder are seen adjusting the large-screen color projector in preparation for a show that is about to begin.

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the offensive suspenders down into his trousers as our film program began. He must have become totally absorbed in it because when the lights came back and everyone arose from their deck chairs, he forgot the suspenders so his trousers were left behind as he arose, to the great amusement of the group! It was wonderful to see famous men like that joking and gaming with each other. The flying-spot motion picture machine that we used during demonstrations of this kind worked beautifully except for one thing. It ran at the television scanning rate of 30 frames per second, whereas the motion picture industry’s films that were being shown had been made at the incompatible rate of 24 frames per second. This led to some rather fast action taking place in some of our shows (125% faster). Furthermore, the sound rose in pitch to give a distressing Donald Duck effect. To offset this latter problem, I was prepared to replace the sound track, whenever possible, with my own voice through a microphone in the adjacent control room. RCA’s large-screen projector soon became the reference standard for what color television of the future was going to be like. It was shown to members of the FCC early in 1947 and we transported the whole system down to the Franklin Institute in Philadelphia in April, where Dr. Zworykin demonstrated it to his peers as he received the Franklin Medal for his leadership in the development of television. The “simultaneous” projector and the flying-spot scanner were two of our projects that escaped the skeptical view frequently taken by our own live-in project critic, Mr. George Sziklai, one of our engineers who’s assignment seemed to be to write up and patent every possible way of making a color television picture, whether it was achievable or not. His many writings may mislead some historians to think that he was lighting our way.

THE TRI-COLOR CAMERA The experimental “triple image-orthicon” color camera that I had been working on for more than a year was now finally ready to be shown. It had been a problem to obtain convergence of its three low-velocity, orthicon-type scanning beams while at the same time bringing into register the three delicate image sections. Convergence was not completely perfect at the corners and edges but,

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overall, for a first try it looked pretty good and it went into immediate operation. We now had a live studio color camera! The new camera was originally positioned opposite my office desk where it could be swung to look out the window or to focus on a person seated in the desk chair. A canopy of fluorescent lamps was hung over the desk to illuminate any comely secretary who might be persuaded to sit there and provide a winsome talking head for viewers in the adjacent projection studio. As we gained experience with the camera, it slipped out of my office and into a corner of the studio next door. Before we knew it (or were ready for it), Sarnoff was making plans to use the new camera in a series of demonstrations of the now much ballyhooed compatible color television system to which RCA had become fully dedicated. One day, a short Hollywood director arrived, complete with beret, boots and megaphone (I wish I could remember his name). He soon developed a series of singing and dancing shows, drawing upon the Powers Agency models from New York. This was a real exciting time because the director brought in quite a few of the world’s most beautiful women, many of them being very well known. I can only remember names like Jinx Fallkenburg and Candy Jones. From the control room you could hear the little director calling out, “give the bosom effect girls”! In spite of all that glamour, the act I liked the best was the Spanish ventriloquist, Señor Wences, and his one-hand, little button-eyed boy speaking in a raspy falsetto voice to the head in the box; “easy” he would say; “difficult” said the voice from the box; “easy for me, difficult for you.” Sarnoff began by giving a show for members of the FCC on 16 July 1947. He loved eye-catching beauty, bright colors, humor, and wit. He was a real carnival showman. In our new little one-camera “studio,” he now started setting up demonstration programs, one after another. The shows would be sent out to various viewing sites in the Princeton area over microwave links (the Princeton Inn was a favorite place). Since we hadn’t yet begun to learn how to combine our three color signals into a single composite video channel, it took three individual microwave circuits beamed from the roof of the lab to get our pictures out. This burdensome three-channel arrangement for transmitting the pictures kept reminding us that our job was far from complete, but we were still flush with the accomplishment we had just

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achieved. We could now produce large, bright, flicker-free and beautiful color pictures in the light of the real world by electronic means alone. Furthermore, our color pictures were sufficiently compatible with the fast-growing monochrome system to be viewable on all existing receivers. Soon new color sets would be in production that could display either service. Match that, CBS! In order to set up and register the three-image orthicon tubes in the new color camera, it was necessary to make dozens of adjustments on it with great care (a precision of one part in five hundred). To do this the person doing the adjusting needed to have a very accurate view of the resulting picture. No color display had ever been built that was as good as the one needed just then. The camera demanded a super monitor to set it up and since no such thing had ever existed before, there was nothing to do but try to build one. The monitor took the form of three 10 inch cathode ray tubes firmly mounted in a T formation (see Figure 14.4). Each tube had its own red-, green-, or blue-colored phosphor. The green tube was set on the horizontal and was viewed straight on

Figure 14.4 The triniscope or three-tube color monitor used to set up color cameras.

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but set back by one tube diameter in a cubical chamber. The red and blue tubes were set vertically above and below the green one and made visible in superposition by intersecting mirrors in X formation. The mirrors were coated with a dichroic (color-selective) film to reflect the color of the tube it was adding to the composite view. You had to ignore the fine line where the mirrors intersected. The best view was obtained when the viewer was seated on a stool with head held on the axis of the tubes. This was intended to be a one-man, close-up, critical viewing device. After the monitor’s own sweeps had been initially adjusted to get perfect convergence of the three screens, the video amplitude controls were set to produce a perfectly white picture. The monitor thus became a reference standard for both geometric convergence as well as color balance of the three color signals sent to it. This monitor produced the brightest, best-converged, and most perfect color pictures that had ever been seen. Copies of it were used in the NBC control rooms when color broadcasting first began. Two of them can be seen on the right in the control room

Figure 14.5 The first entirely electronic color television camera (1947). The author explains how the colors are separated by mirrors before entering the three image-orthicon tubes that will produce synchronized red, green, and blue color video signals.

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Figure 14.6 The “Princeton” camera, used in the color hearings of 1949/50. This experimental camera was the first of RCA’s line of electronic color cameras that opened up the color television era.

Figure 14.7 RCA’s first production model camera, the TK-40, released in 1953). (Photo from cover of Radio Age magazine, July, 1953.)

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pictured on page 120. The monitor was copied in many forms during the few months before Al Schroeder and Harold and Russ Law’s shadow mask color tubes came into production and made triniscope displays like this obsolete forever. At that time, we were close to being able to produce a practical color television system suitable for public use since by we had so enhanced the original crude camera and display devices, created by television’s founding fathers, that they now had color properties. All of our equipment was still just in the experimental stage, of course, but we felt that we were “on track.” Soon the fast growing video broadcasting industry would find our new color equipment indispensable.

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TRANSMITTING COLOR PICTURES

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LTHOUGH WE HAD mastered the fundamentals of a commercial-grade color system, we were still connecting everything together using separate cables for each color. We had yet to learn how to merge the three color signals into a single “composite” signal that could travel over standard (single-cable) communication lines, plug into displays, and be broadcast by radio. This last puzzling phase of color TV development was entirely different than anything our color engineering group had encountered before. We hadn’t anticipated the problems it created, and I think that everyone in the company, with the possible exception of Sarnoff himself, was beginning to sense the magnitude of the problem and worry about it a little. But wasn’t RCA one of the primary communications companies of the world, and hadn’t it already made enormous contributions to the technology of radio transmission services for voice and text, even radio photography? Why worry? As Sarnoff watched his color engineering group chart a path to a fully electronic and compatible public color television system, he may have become a little overconfident in his team. Those were the days at the very beginning of the science of information theory. Claude Shannon of the Bell Laboratories released his paper, “A Mathematical Theory of Communications” in 1948, and Norbert Wiener at MIT gave a summary of his theories on the companion science of cybernetics that same year. We were simply swamped with new information that applied to our problem but with all we were doing, many of us were floundering in our attempts to comprehend the new theories and reduce them to practical terms that could be put into practice. We were eager to Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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absorb and understand everything we were being told because we knew it suggested the possibility of finding the bandwidth compression scheme that we needed for color transmission. In response to this need, two highly skilled communication system engineers were added to the color development group— Bill Houghton, from RCA’s communications division, and Ed Goldberg, circuit design engineer and prolific inventor, from the lab’s analog computer section. These two men would lead the way in resolving the complex problems that we were about to encounter as we set ourselves to compress tricolor television transmission onto a single wire line. Existing studies on sound communication had already showed that the frequency spectrum occupied by speech and music is fully packed due to the complete randomness of the tones that humans produce, along with the many harmonics that accompany them. We knew, moreover, that the energy spectrum of a television picture is very sparsely occupied due to the repetitive scanning of the image, which is done for the sole purpose of refreshing the image in the viewer’s eye at a rate fast enough to preserve continuity of motion and to overcome the uncomfortable sensation of flicker. A motionless monochrome picture produces a spectrum of tightly packed energy bands grouped around harmonics of both the horizontal and vertical scanning frequencies that establish the image raster. When motion occurs, side bands are generated that broaden out those energy bands in proportion to the speed of the action. Since the speed of any physical motion is very small compared to the TV scan rate, there are always large empty gaps in the spectral profile. We reasoned that if we could position the color components of our picture within these gaps, it would open up new spectral territory that might provide a place to form a composite video signal. This would be like finding a new channel in the radio spectrum over which the FCC didn’t have jurisdiction and where, hopefully, we could place our red and blue color components without disturbing the basic properties of the underlying monochrome picture. We soon found that there are certain subcarrier frequencies that magically disappear when viewed on black-and-white TV sets. The frequencies must be odd multiples of one-half of the (horizontal) line scanning rate of the picture. They become virtually invisible because they out-phase (invert) themselves from field to field,

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producing a bright spot in one field and then (almost) nulling it out with a dark spot in the next. Such a carrier could then be modulated by the red/blue color components, delivering them, interference free, along with the monochrome (or green) signal. We were trying to put ten pounds into a five pound bag, but we made it! What an excellent way that was to get everything all together onto a single wire line, ready for cable distribution and radio broadcasting. This principle is the entire basis of the original RCA (now NTSC) color multiplexing system that has endured to the present day. Many frequencies fulfill the requirement for the magic subcarrier just mentioned and in the beginning many were tried in the range of 2.6 to 3.8 MHz. After much study, the final value has now settled down to be 3.57954 Mhz.* As we began experimenting with this idea, our job was made enormously easier when one of the important inventors in the group, Al Bedford (Figure 15.1), came in one day, waving what appeared to be a small cord the size of a mouse’s tail and about that color. Upon closer inspection we could see that it was made up of a large number of brightly colored threads—red, green, and blue— probably from his wife’s sewing basket. What Al had discovered and was showing us that day was the principle of “mixed highs,” which means that since the human eye does not have the visual acuity to discern color in small patches, it merges tiny bits of color into a composite gray, an interesting discovery. If no one can see colors in extremely fine detail, why should the television system be required to carry the cumbersome wide-band video signal that produces them? Using our big-screen theater projector, we quickly tested Al’s mixed highs theory and found that the video bandwidth of the red *Extensive use of the term Hertz (Hz) for frequency is in common use and some my wonder why that is. Why not Avis, Budget, or National? Dr. Heinrich Rudolf Hertz, a 19th century physicist, was the first to identify the presence of radio waves, which are so important to us now. Certain German scientists from the early 1920s began promoting the idea that he should be given due honor for this by attaching his name to the specification of all electrical vibrations worldwide. This would include even electric voltage or current sources such as the 50 or 60 cycle per second power mains. Thus 60 Hz (Hertz) now means 60 cycles per second. We say 10 kHz (thousand Hertz) rather than ten thousand cycles per second or 10 kc. In October 1933, a committee of the International Electrotechnical Commission declared this to be the world’s official terminology. It was not widely accepted in the United States, however, until the 1950s. No other man in history has ever had his name mentioned more often than Heinrich Hertz!

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Figure 15.1 Al Bedford.

and blue components of a picture could indeed be reduced to less than a quarter of their original full bandwidth without losing any apparent resolution. It was easy to see that the fine structure of an image actually comes from the underlying high resolution luminance component of the picture, which is almost identical to the spectral shape of the green color channel, which is all that blackand-white receivers ever display. Color sets, then, need to receive only low-resolution red and blue picture components and add them to the sharp green picture to get the full high-resolution color effect. It is interesting to note that a field-sequential color system can never take advantage of this great economy of spectrum utilization since each of its color components has only the one wide-band video channel to travel through, whether the accompanying high-frequency color components can be seen by human eyes or not. Just as we were getting these ideas together in early 1949, the FCC notified RCA that it was issuing a request for “comparative tests” of the two main competing color television systems, CBS’s field-sequential and RCA’s “compatible/simultaneous” system. We were to make our presentations before them in Washington, DC, starting in October of that year. RCA was thus invited to prove immediately that its promising plan for a completely electronic and fully “compatible” color television system was indeed feasible and close to realization.

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You would think that with all the impressive demonstrations RCA had already given to the FCC showing its progress with color, they would let us continue with the work and in our own time bring out a working system. No, they had to have it right away! People were saying that the FCC probably thought that RCA, being the dominant force in the industry, could drag its feet on color long enough to get so many monochrome sets into the field that none other than their compatible system could ever again come up for consideration. This was probably true and may have been a justifiable reason to insist that hearings be held just then. To us, it was unthinkable that anyone would ever want to go back for another look at those dim, flickery, little mechanical field-sequential color pictures that CBS was still touting. Everyone in RCA knew that it would be terribly risky for us to attempt to put the first experimental model of our composite color transmission plan out on public display. We were still trying to get acquainted with it ourselves! But, apparently, there was no way of getting out of it. A digital sampler operating on one of the “magic” subcarrier frequencies described above had been set up and we could see that the theory of transmitting the color components within the spectral gaps of the base monochrome picture was indeed valid. We could also see that our original impulse to move into a digital technology at that time was slowing us down enormously because every step was such a completely new experience. So, in view of the greatly accelerated time frame, it seemed logical to drop the digital program plan and fall back on our comfortable old analog ways of doing things. The concept we chose to follow then was to let the brightness component of a color travel as the amplitude of our hidden subcarrier, while its color value or hue would travel as the relative phase position of its carrier with respect to some reference color phase position that we would assign. We chose blue. At the receiver, a synchronous demodulator would recover these color components and add them all together as they reached the display device. We didn’t know at the time that we were defining a quadrature modulation system, but, curiously, this is the very system that has survived to this day! The principal problem in carrying out this early plan for a rudimentary color video transmission mechanism was in synchronizing the color demodulators in the receivers precisely with the

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studio master generator. Precision crystal-controlled frequency sources were common in those days, but the matter of locking crystal oscillators together in exact phase at every receiver was an unknown technique and mastering it would prove to be a stumbling block for RCA during the upcoming FCC demonstrations. Various schemes for obtaining a reliable lock between master and slave oscillators were hurriedly tried throughout the summer, but none of them gave us any real confidence. We put the best we had into the system and left for Washington. Needless to say, that sensitive phase-locking problem let us down during every one of the original 1949 demonstrations and brought much public ridicule to RCA. Loss of color synchronization was a highly visible event because whenever it occurred, the picture stopped being in color and simply fell apart. Whenever that happened, the otherwise invisible color subcarrier would now flash across the screen as a series of brightly colored dots. This caused the critics to deride the whole “simultaneous” TV system idea, calling it RCA’s dot sequential color system, thus reducing it to equivalence with the CBS field-sequential system or even CTI’s line-sequential system, which was still being talked about. You know, if you paid any attention to your critics you never would get anything done!

Figure 15.2 The technical mystic of color television was quickly displaced by the personalities of the actors and politicians that it brought forth. This advertisement featured the late Jack Parr.

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Following those first disastrous showings, in a follow-up session in 1950 (after almost every one had gone home), Al Bedford (again) came up with a fully reliable color-lock arrangement that forever eliminated the color break-up problem and remains in use today. It was too late, however, because the commissioners had already made up their minds about RCA and it went virtually unnoticed.

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HE FCC WANTED to see for itself the quality of color TV viewing the industry would be bringing to the public via the radio waves it was authorized to govern. It had become clear that sight had finally and permanently been added to sound and they now wanted to see and legislate upon the quality of the color component that was being proposed. The two major entrants were RCA and CBS, of course, but the Allen B. DuMont company, which really wanted to keep television in black and white forever, insisted on participation in the demonstrations so as to provide a basis for consideration of their prerogative. One other new and little known group identified as Color Television, Inc. also wanted to show their version of a color system. This company had been organized by a group of San Francisco businessmen to exploit the idea of a line-sequential color system based upon inventions of their associate, George Sleeper. As it turned out, when Sleeper’s pictures came to be viewed on RCA’s bright triniscope displays, the inherent inter-line flicker of the system was so annoying that they voluntarily dropped out of the race. The FCC asked to see sporting events, news reporting, live entertainment, and motion pictures. NBC’s programming people would soon be put to the test as they converted their Washington station, WNBW, from black and white to color. The one thing the NBC programmers immediately rejected was the idea of doing professional programming from a studio that had only one camera. That first color camera, the so-called Princeton camera, which I had built more than a year before, wasn’t equipped with a lens turret and other operator-friendly features that professional cameraTele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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men insist on having, so they didn’t like that either. To do a redesign to include those features within the present time frame was simply out of the question, so we just built another camera like the first and brought the two of them to the Washington studio. Receivers and viewing screens of various kinds were soon under construction by almost everyone at the Princeton lab and as many as could be recruited from Camden. Dozens of previously unconnected people suddenly found themselves building color television receivers, whether they had any appetite for it or not. Most of the receiving sets were variations on the direct-view, three-tube “triniscope” configuration, similar to the one I had used for my camera monitor. One receiver was built around RCA’s largest kinescope tubes of the time (16 inch). That one required a cabinet comparable in size to a telephone booth! There were “tube and lens” projection sets similar to the large-screen TVs marketed today, but the pictures they produced were very dim due to the small lenses and the extremely poor screen materials that were available in those days. Since NBC’s Washington studio occupied a large basement room in the Wardman Park Hotel on Connecticut Avenue, NBC was invited to host the shows. The cameras of all three contestants—CBS, RCA, and DuMont—were set up side by side so as to be able to simultaneously televise whatever bill of fair the FCC wanted to see. Each would transmit via its own radio channel to viewing rooms set up in an old “temporary” building in southeast Washington. A few plush VIP suites were also set up in various hotels. The Wardman Park Hotel was a lively place at that time, and many world figures could be seen coming and going through its halls. Those were the days of Harry Truman’s presidency, and I saw him on several occasions, usually around ballroom entries, with Bess and Margaret in tow. Many mornings I sat in the lonely coffee shop with Bernard Baruch, the highly respected elder statesman and advisor to the presidents, but he and I lived in different worlds and could hardly communicate. Although NBC’s studio was originally of a fair size, it shrank quickly with the addition of our two color cameras and all of CBS’s color equipment plus DuMont’s monochrome setup. We got the most space, however, having the advantage of a certain proprietorship. This gave us the main control room for our camera controls and monitors as well as a flying-spot scanner for slides. We

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also had a fast, pull-down 16 mm motion picture film machine that was prone to tearing out sprocket holes in the film, so RCA’s movies frequently got behind the others due to time-outs for splicing. That control room, which was a target site for VIP visitors, was a tight fit for Ray Kell, Al Schroeder, and myself, who spent countless hours there. Senators, members of the House of Representatives, industry leaders, and miscellaneous other government officials came to inspect the studio and visit our tiny control room almost every day. Of all the distinguished visitors that came, the one I remember most vividly was the elderly Dr. Lee de Forest, inventor of the vacuum tube. Immaculately dressed, he was a critical observer (and commentator) on everything he saw. As he was leaving I heard him remark, “this RCA system is a damn good solid piece of engineering”! Senator Edwin C. Johnson from Colorado, my home state, and its former governor, was another visitor. “Big Ed” had the physical structure, general manner and dress characteristics inspired by Teddy Roosevelt. He certainly had the ruddy complexion, goldtooth smile, watch chain, and elk tooth with a voice that could rattle the windows of any senate chamber. Ed had recently become Chairman of the Interstate Commerce Committee which, it was said, held the FCC up by the short hair. As he leaned over to look into one of the color monitors, I spoke quietly into his ear: “Do you remember Charlie Myers in Alamosa?” “Damn, boy!” he said, “that’s my good fishin’ buddy! How you know him?” “He’s my father’s uncle,” I said. Uncle Charlie was another Roosevelt clone. “God damn it, boy! What they got you doin’ here?” he said. “I built the cameras” I said, and he leaned over for a better look. “Beautiful picture,” he said, “Why do they look like shit when they show them to us?” “It’s because we haven’t yet learned how to send them through the radio circuit—we’ll get that fixed pretty soon!” “I’ll bet you do,” he said as he left. A few days later he came out with a statement that RCA had given a fine demonstration and it was second to none. Nevertheless, by the time the hearings were over he had reverted to CBS and endorsed approval of their system. Maybe he suspected that it wouldn’t hurt anything to let CBS have its fling. The official spokesperson for RCA at those hearings was the quiet Elmer Engstrom, vice president for research at the laboratory in Princeton, but acting under him as charge d’affairs of the entire

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Washington operation was the self-confident and very vocal, Dr. George H. Brown, Director of the Radio Systems Laboratory, designated as RCA’s chief witness before the FCC. Brown was an unusually sharp-witted individual who was held in such respect within the radio industry for his enormous contributions to radio broadcasting equipment and antenna designs that it would be hard for anyone, in or out of the FCC, to dispute any comment he might make. Except for George Sterling, none of the commissioners were engineers. Some were former media people and a few were lawyers. Brown was difficult for them to understand and his technical prowess was completely lost on them. I enjoyed hearing the reports of his colorful testimony as various staff members brought the stories of the day back to us in the studio. An example was his flippant reply to a Commissioner’s question, “Dr. Brown, does RCA have any other methods of producing color television pictures”? Answer: “I don’t know because I haven’t been back to the lab in two weeks!” The master of ceremonies for all of the entertainment that NBC produced was a little puppet named Kukla who was in charge of a small troupe of actors from Burr Tilstrum’s, Kukla, Fran, and Ollie show. What a wonderful little troupe they were! Their classic TV show was a delight for everyone! It aired on NBC regularly each day from our crowded studio via NBC’s black-andwhite cameras, which were wheeled through the crowd just before network time, setting aside any FCC considerations.

Figure 16.1 George H. Brown.

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Figure 16.2 Kukla, Fran, and Ollie.

One hectic day, the studio was unusually crowded due to color demonstrations that had run right up to the scheduled air time. That day, the NBC crew found it physically impossible to get the black-and-white cameras through the crowd and over to Burr Tilstrom’s set, but our color cameras had been there all day watching little Kukla do his grand master of ceremonies act. So on the evening of October 10, 1949, the show went out on the NBC network via the color cameras. At that time, the network didn’t reach any further than Boston and Chicago, but it carried the very first compatible color TV transmission ever to be put on any network. Curiously, it didn’t arouse a single comment from the black-andwhite audience, and no one reported having seen the show in color either. Compatibility was certainly demonstrated that night. Each of the contending companies was expected to originate sample types of programs to illustrate the breadth and versatility of their system. Whenever possible, they would include something that could possibly embarrass one of the other companies, as when RCA put in fast-moving things like jugglers, baton twirlers, and acrobats to show the color breakup of the CBS’s field-sequential system. The most elaborate offering attempted was NBC’s 15 minute version of Guy de Maupassant’s “The Necklace,” staring Nanette Fabray who played the unfortunate Mme. Matilda, who was required to compress 10 years of her life (and fading charm) within that time period. The humor of the attempt was the best part of the show!

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Allen B. DuMont, the black-and-white TV proponent, offered an amusing program involving a wrestling match between two black men followed by a formally dressed choral group of more black men in white shirts and black ties with white carnations in each lapel. The message was, who needs color television? The evening before those wrestlers were to perform, they practiced on their padded mats, which they left on the studio floor when they left about midnight. Peter Goldmark and his crew were still tuning up their equipment and a few of the NBC people were also hanging around. As it happened, one of NBC’s sponsors was a brewing company that made a product called Champeer, chilled samples of which were always abundantly on hand. By that late hour, quite a bit of Champeer had been sampled and a warm and cheerful camaraderie had spread across the studio. Someone suggested that the competition between CBS and RCA over whose color system was best could most logically be reconciled once and for all right there by facing off Peter Goldmark (Figure 16.3) and myself on those mats, CBS versus RCA in mortal combat. Neither of us knew what we were doing, but we had to take a few mat burns before we satisfied that crowd! I really liked Peter Goldmark and I think he will always be remembered kindly for his creation of the 33⅓ rpm vinyl records

Figure 16.3 Peter Goldmark with one of his famous color wheels.

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Figure 16.4 Engineers Walt Howath (left) and John Johnson (right) focus the two cameras upon Miss Gladys Swarthout singing before the Federal Communications Commission in 1949.

that really started the hi-fi stereo sound movement and served us so well until cassette tapes and CD-ROMs took over. The only thing that came from that dismal encounter with the FCC in 1949/50 was their approval of the CBS system, which forced that unfortunate company to proceed with it’s uphill battle to produce a color television system around their large whirling color wheels and still satisfy an ever-enlarging black-and-white audience. Having no manufacturing facility of their own prepared to build any kind of television sets at all, it was a welcome relief to CBS when a directive from the U.S. Mobilization Director in October 1951 was issued that demanded that the manufacture of color TV receivers be stopped due to “priority demand for materials needed to fight the Korean War.” The matter of field-sequential color television as a national standard was now finally settled! There is more to be said about those color television hearings of 1945/50, however. They had not been the total loss for RCA that they appeared to be at the time. Having briefly seen the benefits to be found in RCA’s “simultaneous” method of transmitting color

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Figure 16.5 Ray Kell stands at the flying-spot film scanner in the tidy little control room for color at the NBC studios in the Wardman Park Hotel. My camera monitors are on the right.

pictures, professional engineers from all around the country were now showing an eagerness to lend a hand to find and standardize a mutually agreeable transmission system for it. Just as when the original black-and-white system seemed ready for commercialization, an industry committee was formed to define specifications for it and act as a guide for the FCC. That was called the (first) National Television System Committee, or NTSC. Now a new (second) National Television System Committee was proposed. The leader of this proposal was GE’s W. R. G. Baker, who also represented a powerful industry group, the Radio Television Manufacturers Association (RTMA). Although the idea was met with only grudging consent by FCC chairman Wayne Coy, it took Baker less than two weeks to get more than a dozen interested organizations to assign their most highly skilled engineers to the new committee. Prominent leaders in this second NTSC included Donald Fink, editor of Electronics magazine, Dr. Bernard Loughlin of Hazeltine Laboratories, and David Smith of Philco. Even CBS’s Peter Goldmark joined the fray. Now, the best engineering brains

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in the country would focus on what was previously RCA’s problem alone. One of the collateral features of this arrangement was the opportunity that it gave these other aspiring companies to contribute ideas to this final phase of the nation’s color television system and to bask in the glory of its conquest. As it turned out, except for one major improvement in the basic concept of the color modulation scheme, which was invented by Hazeltine’s Bernie Loughlin, most of the ongoing improvements still came from RCA and, in particular, from Dalton Pritchard in our color group, who added a number of new innovations to the color multiplexing scheme at that time. The engineering details of all this are so complex and lengthy that they are best left to Dr. Brown’s book, And Part of Which Was I, which describes it very well. Brown concludes his description of the mission with the following statement: “The work of this second NTSC was an outstanding example of cooperation on the part of a large number of engineers joined in an effort to bring about the best solution to a major technical problem of common concern.” There was a little bickering at the end, however, about whether the system should now be referred to as the “RCA Color Television System, operating on standards proposed by the NTSC,” or to simply call it the NTSC Color Television System. With so many people in that last scene, it came to appear that the final, transmission technology, portion of the entire color development project was really the only noteworthy part of it. The NTSC Color System, indeed! David Smith of Philco immediately put out public statements depreciating RCA’s part in having originated the most basic principles of the compatible color system as well as it’s cameras and displays. This stung us a little and provoked Sarnoff, but he remained silent. In spite of that last dig we came away proud to have been members of an American enterprise that put in place the world’s first successful color television system. Humanity now had its vision! Meanwhile, the color studio in Washington found diminishing use, although a temporary field lab was set up in a rented store building on the outskirts of Silver Spring, Maryland to continue live field tests using color transmissions broadcast several hours a day from the Wardman Park studio. These were the very early days of UHF broadcasting and, among other things, RCA was eager to have the

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FCC take notice of that little-used portion of the radio spectrum. An experimental UHF transmitter was hastily built by lab engineers Joe Reddick, Bill Behrend, and Wendell Morrison and set up near the Wardman Park studio. This allowed day-long field studies of color broadcasting to continue. During these studies, a particularly annoying dot pattern was seen in color receivers whenever they were tuned to monochrome channels. When receiving color pictures, no such problem occurred; but since much of the programming was still in black and white, it was important to overcome that defect. It was Harry Kihn, of the receiver group at the Princeton lab, who suggested a circuit be installed in color receivers that would simply turn off the color demodulation system whenever the color burst signal was missing, as when receiving monochrome. When Kihn’s patent on this was issued, the Wall Street Journal thought enough of the event to head a paragraph describing it as “Kihn’s Kolor Killer.” By 1953, the primary source of color television programming was moved to the Colonial Theater in New York, where many of the early color shows were produced (Figure 16.6). The theater

Figure 16.6 First public showplace for color television equipment and programing, the Colonial Theater in New York City. Photo courtesy of Sarnoff Labs.

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was also a showcase for the latest commercial studio color equipment that RCA was eager to offer the industry. To get this ready, engineers from the commercial products engineering group in Camden had been commissioned to transform my cantankerous old laboratory camera into a more user-friendly device. They did this beautifully and very promptly. Their first camera, reported by J. D. Spradlin in an RCA Review paper in 1952, was a practical interim studio camera for NBC. It had a multiple lens turret and a compact optical system for separating the color components into the three image orthicons. In 1954, the camera was further enhanced for production and identified as the model TK-41 (Figure 16.7). This camera stretched to a length of nearly five feet and weighed over 300 pounds. On the heavy duty motion picture tripod it required, it weighed more than five hundred pounds! As unwieldy as that camera and its successors were (TK-44, TK-45, TK-46, and TK-47), they were the workhorses of the television industry for more than 25 years. The first demonstration of the new color system took place on October 15, 1953 at the request of the FCC. Thirteen receivers were set up in a ballroom at the Waldorf Astoria Hotel in New York and NBC provided color program material as a part of its reg-

Figure 16.7 The RCA TK-41 color television camera, industry standard for 20 years. This particular camera is preserved with other TV technology at the University of California film and television archive and was once owned by Red Skelton, famous TV comic. (Photo by courtesy of Edward Reitan.)

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ular Channel 4 service. There were many new faces on the Commission by this time and they seemed very pleased with what they saw. On December 15, 1953, they released their final decision to accept the NTSC specification as the law of the land and authorized commercial broadcasting to begin on January 22, 1954. David Sarnoff, who had anticipated that the public would immediately jump to order color sets, was greatly disappointed when it then took so long to arouse public interest in color. RCA suffered almost 10 years of enormous programming expense to build public confidence in the viability and permanence of the NTSC color system, and to loosen buyers pocketbooks.

CHAPTER

17

DELAYED BROADCASTING

A

S SOON AS television moved beyond the pure-amazement stage and got into the hands of the broadcasters who were in the business of routinely programming it every day, there was an immediate demand for delayed video playback equipment. Audio recorders, both tape and disk, had served the sound broadcasting industry very well for many years and had reached such a high degree of technical excellence that their presence in the system could hardly be detected. Television broadcasting demanded the same service. The first thing that anyone could think to do about it was to focus a motion picture camera on the studio monitor and hope that the films from it would play back through the motion picture scanner. The camera would have to run in synchronism with the television picture, of course, and have a sound track so as to provide composite sight/sound films. This arrangement worked fairly well and the films generated were called kinescopes, or “kinies.” These pictures could be run on any studio film projector and were thus available for rebroadcast whenever needed. This was just an interim procedure and was used only through the early black-andwhite era. It was never a favored program source as the kinescope films had a distinct lack of snap and sparkle compared to live studio pickups, but this was the best the industry had available for a long time and it was universally disliked. When color came along, the public was ready for something very much better, something that could compete with the professional Technicolor motion picture films that were being used steadily for everything but live studio camera events. Again, attempts to make color kinescope films turned out to be about as dull and lifeless as the old monochrome kinies. The industry had Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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a serious need for a really transparent video recording system for color broadcasting. David Sarnoff was quite aware of this problem when he issued one of his “birthday present” wish lists. A high-quality video tape recording system headed the list and you would expect that with all of the engineering talent within those RCA laboratories, which had already brought about so many miracles, there would still be one more genie in the bottle waiting to be let out at the urgent call of the master, but there wasn’t. My days at the lab were over by the time this crisis developed at RCA, but the many friendships I had among my former colleagues provided a fairly reliable running account of the events that transpired during the pursuit of Sarnoff’s next “birthday present.” Harry F. Olson, whom I knew and admired as the designer of RCA’s microphones, loudspeakers, and audio disk recorders, as well as the studio-grade stereo tape sound recording equipment, was the undisputed guru of all high-quality sound equipment being produced in the country at that time. He occupied about the same authoritative position in the audio portion of the radio industry as George Brown did in broadcast transmitters and antennas. Like many of the engineers at the lab, I was one of the audiophiles of the day who would seize any opportunity to get into Olsen’s lab for a chance audition of whatever might be going on in there. What magical sounds those people could produce with their state-of-the art technology! Who then, would have been a more logical group leader within RCA to be called upon to extend magnetic tape recording into video? Olsen and his group were the obvious choice but, as it turned out, they didn’t win any Oscars with their attempt in that field. Olson and his team had brought audio tape recording to such a high standard for the sound broadcasting industry that they must have looked upon video recording as just a higher-resolution version of what they had already done. Perhaps this is what locked Harry and his staff to the old fixed head/moveable tape idea called the “Simplex system.” They boldly planned to increase the tape speed up to an enormously high value in order to imprint the video frequencies upon it, frequencies more than 200 times greater than audio. You can probably anticipate the problems that lay ahead of them.

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By late in 1953 Olson did indeed have a simplex-type video tape recorder running, but what a recorder! Instead of the 15 inches per second tape speed used for high-quality audio, his new video recorder was running at 30 feet per second, which is about twenty miles an hour! With 17 inch diameter tape reels spinning, at times up to more than 2000 rpm, the recorder had a capacity of only four minutes playing time per reel. The picture quality was not at all that great either. For safety, the operator was equipped with heavy leather gloves and goggles because the monstrous device was considered a hazard to life and limb. The NBC operating people were not at all pleased with the birthday present that their boss was about to receive! Had Olson done a serious search of the literature, or even taken a careful look within RCA, he would certainly have chosen a very different approach to his video recorder design. The technology of the time had already shown the idea of increasing the speed between tape and head by simply spinning the recording head from side to side across a broad tape, thus allowing the tape speed itself to remain at a low value. Surprisingly, one of RCA’s own people, Earl Masterson (Figure 17.1), an extremely talented young man but lacking with an

Figure 17.1 Earl Masterson, self-educated electro-mechanical-optical engineer from Kokomo, Indiana, pioneer of magnetic tape recording for sound. He was the first to conceive and patent (RCA, 1950) the high-speed moving-head idea for videotape recording. RCA failed to take advantage of his invention.

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engineering degree and working obscurely as a technician in the Camden factory, had already filed a patent case for RCA on a helical method of scanning magnetic tape, and RCA’s own patent department had processed the invention as U.S. Patent #2,773,120, filed Nov. 30, 1950. It was titled “Magnetic recording of high frequency signals” and was issued by the Patent Office on December 4, 1956 (Figure 17.2). In Masterson’s system, one turn of tape was lightly wrapped around a smooth cylinder carrying an embedded recording head rotating at high speed. Each turn of the head produced strips of video information slanting across the width of the tape, one video field after another. This process ultimately became the standard of the broadcast recording industry, but RCA’s connection with it and with Earl Masterson, the inventor, seemed never to have been heard of within the company! Masterson found other employment shortly thereafter, and many years later I met up with him and heard his story when he was a highly respected research group leader at Honeywell. Here was a case, not uncommon in large institutions, where gifted and highly qualified individuals, submerged by lack of spectacular academic credentials, can be forced to sit on the sidelines, watching and longing to apply their talents to the action, but denied that opportunity. Had Masterson’s invention been recognized at the time, RCA’s future might have taken a very different turn. Meanwhile, on the other side of the country, a group of engineers at the Ampex Corporation were doing some very clever work in tape recording in connection with black-and-white video recording. They had created a four-head transverse (quad) type of video recorder that did black-and-white videos beautifully but was not set up to handle color. It was the hit of the 1956 NAB (National Association of Broadcasters) convention in Chicago, demonstrating such outstanding monochrome pictures that within a few days nearly 50 of the machines had been ordered at a price of $50,000 each. David Sarnoff’s birthday present (the recorder) would not be ready for delivery to him until next year’s NAB convention, at which the NBC people were already scheduled to make the presentation and were shuddering as they contemplated the event. Sarnoff had never been made fully aware of the problems of Olson’s video recorder so it was showdown time! First, NBC explained that they would require six of the recorders since each

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Figure 17.2 Earl Masterson’s patent.

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could only produce four minutes of program due to the time lost in bringing them up to speed and then slowing them down again. At about this point, O. B. Hanson, then Chief Engineer of NBC, became more explosive and finally laid out to Elmer Engstrom how hopeless the situation really was. In his quiet way, Engstrom approached Sarnoff with the news that his birthday present had soured and could not be delivered. At this, the resourceful Sarnoff simply shrugged and ordered that the Simplex video recording project be laid to rest. He then immediately arranged an agreement between RCA and Ampex whereby RCA’s color engineering staff and the video equipment engineering department in Camden would combine their skills to bring the Ampex machines up to recording in color. From there on, a cross-licensing agreement would exist between the two companies. Everyone breathed a huge sigh of relief. Conversion of the Ampex machines to color was a major project for RCA, however. The Studio Equipment Engineering staff in Camden headed by Anthony Lind and Archer Luther worked closely with Princeton’s color development group. These were my old friends, Ray Kell, Al Bedford, Gordon Fredendall, Eric Leyton, Dalton Pritchard, Al Schroeder, and some new people whom I never knew; to them it was just more “simple engineering” I expect! Ampex and RCA thus became the two original sources for those now highly perfected video tape recorders that we viewers have enjoyed for so many years.

CHAPTER

18

GOODBYE RCA

T

HE CONCEPT OF bringing entertainment, news, and advertising into peoples homes by means of a wireless “radio” connection was the first dramatic step in the development of mass communication in our modern world. Add to that the development of a color television system, pretty much as I have described it here, and you see what a company called the Radio Corporation of America (RCA) contributed to humanity during its relatively short life in the twentieth century. These were business goals of its leaders to be sure (i.e. money making), but they were based on an amazing foresight and confidence in technical accomplishments. The driving force behind this risky concept was a unique individual, David Sarnoff. Very few business men approach money making via the torturous, risky, and uncertain path of promoting scientific enlightenment in the minds of the people they employ. Thomas Edison, who relied so much on his own technical skill, exemplifies one of the successful few. A much safer path to corporate longevity, productivity, and financial stability can be found by manufacturing simple, well-established products, that can be moved to dominant positions through clever marketing and ballyhoo alone. To accomplish the things he wanted to do, Sarnoff knew that he had to employ people highly educated in the physical sciences and place them in a quasiacademic setting. The laboratory that he built in Princeton, New Jersey was just that—a haven for scientists and engineers where they could work comfortably to extract nature’s secrets and turn them to the utility of mankind. This was the brief Camelot that I have referred to in this book. Marketing, however, was not Sarnoff’s strong point. He sought security in product origination, income from patent and liTele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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cense royalties, broadcasting revenue, and the novelty of being the first to manufacture new, glamorous things in which he could participate and for which he foresaw a large public demand. Even in the earliest days of radio, when RCA led the way in that dramatic new technology, it’s level of sales were quickly overtaken by a host of “come lately” companies that were able to market the products far better than RCA ever did. By the time that Sarnoff arrived at a point in his life where his ambition for further technical achievement was waning, the now top-heavy organization he had built was ill prepared to run a business (any business at all) purely as a classic competitive enterprise. It needed an entirely different kind of management atmosphere to hold its place in the highly competitive broadcasting and manufacturing field that he himself had spawned. Even so, RCA had earned such an unprecedented position of leadership in the world of electronics that it is an enormous tragedy that powerful management resources could not have been brought in soon enough to preserve it from decline. Except for John Burns, whom they tried as president briefly in the mid 1950s, all of the subsequent top executives were promoted from within, all of them holding the established RCA mindset that simply was not in sync with the increasingly competitive electronic world. The real downfall of RCA began in the late 1960s when Sarnoff’s son Robert took charge, brought in some of IBM’s product planning and marketing people, and announced that RCA was preparing to go into head-to-head competition with that huge giant of both the original mechanical business machines and now the newly emergent electronic computer industry. It was good that RCA engineering had already established the very reputable Bizmac line of business computers in the early 1960s and had recently brought out the world’s first solid-state, general-purpose computer. But that wasn’t enough, and RCA lasted in that competitive business only until 1970. The great shame of it all is that RCA had played such an important role in the original development of both analog and digital computing. Our own Art Vance (an early TV circuits designer) had led the way in analog computers, directing the construction of the largest (postwar) analog computer for the U.S. military ever made, and our Ed Goldberg was the inventor of the famous “chopper stabilized amplifier,” which was such an important part of precision analog-type computers.

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Also, RCA made some of the very earliest inventions in digital computer memories. The lab’s Dr. Jan Rajchman provided the first 256 bit electrostatic memory tube for John Von Neumann’s original IAS machine at Princeton University. That tube, called the “selectron,” even became a brief commercial item for RCA when it was enlarged to 4096 bits. It was said to be selling for $8000 before the competitive Williams tube replaced it. Even my two principal technicians, Walt and Frank Howarth, were moonlighting as wiremen for Von Neumann, firming up that haphazard pile of tubes and wires that he and his students had fashioned into the world’s first “stored program” digital computer. One day, Jan handed me one of his first magnetic-core memory planes. It resembled a tennis racket with little black beads woven into the intersections of the strings. He had managed to get one of the nearby pharmaceutical companies to press his magical ferrite core mix into small toroids on one of their pill making machines! These things were done by RCA long before any serious attempts to design commercial computer products had begun anywhere, but they contributed very little to establishing a posture for the company when it made its attempt to become a serious supplier of business machines. Only extreme marketing skill could have done that. Furthermore, the timing of its entry into the mainframe computer business was working against RCA because the era of the huge centralized mainframe computers, with their expensive specialized programming, was waning. IBM’s experiment with “distributed” small personal computers would prove to be too successful. Those far less expensive little machines we started to see in 1981, which used a far less expensive universalized programming language, would open up an enormous new and yet unseen market for computers. What a break it would have been for RCA to have foreseen such a future for the small machines and used its then-huge resources to develop that version of computing! They would all have required every kind of RCA component part, particularly picture tubes for their displays! As it turned out, once RCA’s downward spiral began, there seemed to be no way to arrest it. Finally, in 1981, Thornton Bradshaw, one of the country’s top corporation “savers” was given the task. Except for reestablishing NBC’s firm position in broadcasting by placing the skillful Grant Tinker in charge of it, his effort to overcome the Asian invasion in electronic manufacturing was of

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no avail. By 1985, Bradshaw could see the handwriting on the wall; it was unlikely that RCA’s cost structure could ever be trimmed down enough to make it competitive in the new world economy. This being the case, Bradshaw was a susceptible listener at a party arranged by a Wall Street firm at which GE’s CEO, Jack Welch,* was also in attendance. The two men hit it off right away and almost immediately began measuring the fits that the two companies might have in a consolidation move. It was no surprise that their activities would mesh so readily; after all, the two companies had been traveling parallel paths for 50 years! On 11 December 1982, GE purchased RCA for $6.3 billion in cash, the U.S. Justice Department having canceled the 50-year-old consent decree that denied GE ownership of stock in RCA at the time it was originally spun out of the consortium and set on its own course. The two men who remerged the companies are said to have been unaware that such a consent decree ever existed! And so it is, the new pushing out the old, and the old being readily forgotten, a little like the way the cliff-dwelling Indians disposed of their refuse, including dead bodies, by simply pushing everything over the edge. It was in this atmosphere of irreverence for the past (as we surviving RCA engineers perceived it) that the current NBC program staff, now all GE employees, presented their “celebration” of NBC’s 75th anniversary on Sunday night, the 5th of May, 2002. Many of the engineers I have mentioned here (having lived so long) were eager to view the program, which they anticipated would probably review some of RCA’s technical accomplishments of half a century ago, perhaps even ones that they may have had a hand in. But it was too late, RCA was over the cliff already. Not a word was said about RCA, nothing more than a poor picture of David Sarnoff that had to wait until the closing moments of that three-and-a-half hour show to make its brief and silent appearance! Heck! At first, we had the usual negative human reaction—what do you suppose they were trying to tell us? Had there ever been a David Sarnoff, an RCA (and us), or was it the tooth fairy that put in place the television system that now so generously employs the current management? We stewed in that juice for a couple of *See Welch’s book, JACK Straight From the Gut, p. 125.

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weeks before it gradually began to come through to us that these “new” people are just like we were when we first came to work at RCA. We certainly had given very little thought or bowed to any memory of past contributors like Baird, Jenkins, Nipkow, Dieckman, Rozing, and the others who handed the baton to us. We saw our job as picking up and carrying on with what we found already in place, and accepting the challenge of the future. Furthermore, none of us was still hang around with the new NBC team as we occasionally did in the old days. They have no reason to know any of us now or even know the history of television as I have described it here. We thank them, however, for taking us on such a pleasant nostalgia trip through those dozens of early shows from their files, lingering with the most memorable personalities, a few of them still in person! Like the twin towers of the World Trade Center, RCA has disappeared, not because of any great hatred of what it stood for or had done, but simply in the course of the irresistible ebb and flow of human events. Bradshaw and Welch certainly had no delicate sentiments for RCA, never having known the people who formed it, loved it and gave their life’s work to it. Sentimentality is profit-

Figure 18.1 30 Rockefeller Plaza, New York City (the RCA Building).

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less and those who manage great enterprises must remain blind to it. Perhaps we should be thankful that there are men like these who can cut through the broad outlines of things, impersonally and impassionately, patching them together for the ultimate benefit of the ongoing civilization. When we switch on our televisions and view events occurring any place on or off the earth, we simply enjoy the service it provides and take the whole thing for granted. By now, it’s just a dream that my friends and I ever had anything to do with it. It seems to have always been there and everyone in the world has a vested right to use it. This is how the world rolls along and all of us who have lived it and participated in its activities are grateful for the joy we had in being a part of it! Goodbye RCA!

CHAPTER

19

THE BEGINNINGS OF DIGITAL TELEVISION

A

T THE TIME these words are reaching paper, the word “digital” has become a magical advertising lead for every electronic product that anyone can think up. We have digital watches, telephones, pianos, videodisks, hearing aids, space positioning, and even digital television. If a product is really any good, its inside workings have to be based on digital technology. Old analog things are obsolete and should be tossed out. Why is this so? Why are the new digital products so much different and better than the original analog radios, televisions, and radars that emerged in the beginning? There is any easy explanation for this. All simple analog technology is based upon the idea that the magnitude of an electric current or voltage is to represent, or be analogous to, something in the real world, like the loudness of a sound, or temperature, speed, number of dollars, or whatever dynamic entity we might want to describe. On this basis, varying values of electric voltage, moment by moment, describe a particular subject. Think of voltage fluctuations as ranging from zero to one volt. Unfortunately nature has endowed electric circuits with a certain (nuisance) randomness, a wavering, sizzling noise effect that mixes with our analog signal voltages to create an uncertainty in them to such an extent that even the very best electrical representation of a particular entity by analog means can never be done more accurately than to about one part in a thousand. Thus, a million-dollar transaction would come through a simple analog system as $1,000,000 plus or minus $500.

Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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For that reason, analog processing of data more detailed than simple voice and elementary picture transmissions was just not good enough for an expanding world of users, innocently unaware of the foibles of nature, but highly attuned to the practical needs of vast human populations, all of whom are known to have pocketbooks. Something had to be done to make electronic information handling more precise and reliable than analog techniques would permit. By the middle of the 20th century, the just now visible world of electronics was beginning to wake up to these facts and was preparing to sharpen up and get down to serious business. To bring this about, there had to be a radical change in the thought processes of the trendsetting engineers and educators. They would have to give up the old practice of living with tiny, noise-laden, analog signal voltages, and develop a new attitude, namely, to forget about dealing with small signal voltages and deal only with large ones. Whenever a substantial impulse arrives someplace, we’ll call it a “one.” If nothing, or practically nothing shows up, we’ll say that a “zero” has just been received. Notice how this immediately defines a binary or two-state system: on/off, something or nothing. Furthermore, when we add words like now, when, whenever, and so on. we accept the time dimension into our communication system. Time is such a familiar, reliable, and infinitely available nonsubstance. It has the property of never having to be transmitted from place to place since it is already everywhere! All we need to do is lock-step with it and allow it to carry a large portion of the communication process. This new concept for transmitting information was immediately called “digital” because of its association with numbers. It works so very well since it allows the signals in our communication systems to act always at their full strength. This alone improved the reliability of data transfer by close to a thousand times! But that isn’t all; it allows us to introduce nonintrusive error checking codes into the data, which can eliminate errors altogether! The digital transmission system forces us into a totally new language of time-based ones and zeros. Instead of saying “hello,” we would say “101101101011110100001110101011100011001,” which is spoken in the ASCII dialect and said very fast, like at perhaps a hundred thousand bits per second or faster. A bit is just one of those ones or zeros. A byte is generally taken as a group of eight

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bits, which defines each of an alphabet of characters and their properties. By weaving code patterns into clever designs, the professionals who know how to do it can describe everything known in the physical world, vague as that idea may seem. It is the code pattern alone that carries the information, not the physical value of any signaling voltage present in a computer or communication circuit. Digital code patterns, traveling in time, can pass through the universe as though it were transparent or, perhaps, not there at all. Time, that friendly and completely nonphysical entity, which we know more accurately than all else, now plays a primary role in our new communication technology. It took centuries for humans to develop the spoken and written word codes that allow us to communicate with each other as we do, and it is easy to see that the process is not over. The creation of coding comes under the general heading of “software development” and is likely to be a part of human activity for centuries to come. Without attempting to venture deeply into the software arena, we can gain some familiarity with our new binary world by looking at the way our well-worn decimal number system transforms into it. Everyone knows that a quantity written as 742 really means that we are going to add together seven hundreds, four tens, and two ones to express the quantity. Writing the numbers from left to right, we allow those on the left to be given the higher weights. In binary arithmetic, the same is done even if it looks strange, because we see only ones and zeros on the paper and the positional weights are from the binary number series, 1, 2, 4, 8, 16, and so on. Here is an example: Binary bit weight values on the top 512

256

128

64

32

16

8

4

2

1

1

0

1

1

1

0

0

1

1

0

Ten-bit binary string for decimal value 742 on the bottom Add up the positional weights where the ones are and you will find the quantity to be 742 in decimal. This ten-bit binary string can only express numbers from zero up to 1023 in decimal. Larger numbers require longer strings, just as decimal numbers do.

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Proceeding with this concept, some readers may feel nostalgic and ask, how different is this 1/0, on/off (binary) system from the telegraph system that was developed in the railroad days of the late 1800s? The answer is, not much! When an operator held the key down, the distant operator heard a down click. When he lifted it, an up click was heard. Time played a part in the code of those times, which was a sequence of short and long intervals between those clicks (dots and dashes). The dashes were made noticeably longer than the dots so the clicks heard at the receiving point were distinguishable. Thomas Edison’s early work on telegraphy had to do with transforming those codes into readable print, resulting in ticker tape machines. The biggest change that has taken place in the technology since that time is the speed of transmission and the source of timing of the ones and zeros. When human operators tapped their keys, the timing was entirely in their own hands and a data speed of 60 (seven-character) words per minute was top for most operators but the average operator could only make about 20. Mechanization of telegraph transmissions began when a French engineer by the name of J. M. E. Baudot (1845–1903) brought some organization into the business by putting a mechanical clock in charge of timing the release of the ones and zeros on the line in uniform code groups that defined specific letters and numbers as would have been pressed by the operator on a typewriter-like keyboard. The character rate was about ten per second. Each electric pulse was called a mark or space in those days (now a one or zero). Thus, a rate of one bit per second came to be known as one Baud, but that terminology is rapidly fading away. Vacuum tubes could be (and were) used to build the early digital information processors (computers) but the enormous number of them that were required made such machines completely impractical. This was adequately illustrated in the early days of digital computers, when only very small machines could ever be built and the huge amount of power they consumed required them to be housed in heavily air conditioned rooms. It was the transistor and, particularly, high-density integrated circuits that made entry into a digital computer age possible. We have seen how television evolved in its natural analog fashion just as radio broadcasting of voice and music did. Television differed only by its requirement for an illuminated time surface (display) to organize the two-dimensional (analog voltage vs.

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time) video signal into a structure that the human eye could recognize as a visual image. Although any information transfer system, whether analog or digital, can deliver signals to a television display and create a picture, the quality of such pictures is greatly improved by the noisefree digital transmissions now available. It also turns out that there is another important advantage to digital—it opens a way for absolute message privacy to be practiced in the transmission of pictures. This has never be accomplished by any analog means although many attempts were made by the film companies to create analog “pay to view” movie systems. Many serious requirements are found for privacy in the sinister world of politics, government, and “big business,” whose operatives require that the transfer of information among them be kept absolutely secret. Some form of information security has always been practiced in the management of every society from the beginning of time, and for that reason, the prime movers in the development of cryptographic technology were always government agencies. As technology changed, the methods of information security had to change with it, improving slowly as time went on. By the time television imaging was available, the complexity of the technology had risen to such a level that attempts to obtain absolute transmission security for analog video appeared to be hopeless. In spite of that, the users, ever immune to the proportions of technical problems, still demanded fully secure picture circuits. As it turned out, just as I was closing the curtains on my career at RCA and returning to the University of Denver, where I anticipated a more calm academic career awaiting me as a college professor, the U.S. Signal Corps at Ft. Monmouth, NJ was drawing up specifications for expanding the use of television cameras in military situations. Apparently, they were also aware of my personal movements since experienced television engineers were in short supply in the mid-1950s. They issued to the university a request to bid on something like “Special Studies in the Military Applications of Television.” At that time, many universities were taking advantage of government funding of research projects like this, and the University of Denver was no exception; we submitted a bid. In the beginning, our studies were confined to simple analog technologies that would make it possible to do such things as drive an unmanned jeep, tank, or drone airplane by remote control

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using a television camera for vision. The problems were initially confined to manipulation of the radio spectrum, which suffered the effects of multipath echoes, fading, and so on, as would naturally occur due to the vehicle’s changing environment, and this ruined the pictures. Little by little, the Signal Corps pressed us toward much more complex methods of protecting video transmission circuits, citing the need for ways of actually encrypting video signals so as to avoid potential “interception” by opposition forces. In the course of a year’s study at the University it had become quite clear that if the analog television pictures we were dealing with could be converted into a digital bit stream, encryption of the resulting binary numbers using one of the new (1956) digital computers might accomplish that objective. Computers made of vacuum tubes were already doing simple additions and subtractions on binary number streams and were being used to create secure voice circuits. Assuming that this could be done for television pictures, they, too, could be released over open microwave links with all the assurance of security that the highest-level voice encryption techniques could already offer. It would not be easy to convert television pictures into digital pulse streams, however, because of the extremely large amount of data each picture frame contains, redundant as it is. Pulses would have to fly faster than any had ever done before, since pictures must be continually refreshed at least 30 times per second to prevent flicker from making them extremely uncomfortable to view. It should be remembered that we were living in the mid1950s, when no mass memories were in existence and it was strictly a vacuum tube world. It would be no problem to digitize a video signal at a rate that could keep up with the speed requirement for flicker, but there was no commercial microwave transmission equipment in existence that could handle more than a 6 MHz analog video channel. We made the assumption that such a microwave circuit might handle a 6 megabit digital signal as well because each bit bore a close resemblance to one analog sine wave cycle, and there was no alternative. We began the process of converting analog pictures into digital bitstreams at the University of Denver in 1956, but there were many attractive diversions for electronic engineers during those early years and I was not above being drawn into one of them. This temporarily interrupted the work I had just begun on digitizing television pictures.

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By 1958, when the Signal Corps again approached me to continue the digital television work I had begun at the University, I had been taken over and set up in a beautiful new industrial R&D building in Broomfield, Colorado (Figure 19.1). A large manufacturer of air conditioning equipment had need of an electronic engineering group to design a special-purpose analog computer to put in control of their new cooling system for the up-coming DC-8 jet airplane, and by chance they pulled my name out of the hat. The company had developed a very lightweight but 75 horsepower Freon compressor that they knew would be very difficult to control—a turbine running at more than 100,000 rpm from jet bleed air. Upon design approval, our new little company would manufacture the controllers as required. It was agreed that beyond the controller work, I was authorized to develop government contract research projects at will. Fortunately, the air conditioning controller work was essentially finished and we were starting to build general-purpose analog computers for the aerospace industry when the Signal Corps project came up and gave me that wonderful opportunity to get back to working on the digitizing of television pictures. Our bid for the work was accepted and again we would be working under the sharp eye of my friend John Rice at the Signal Corps in Ft. Monmouth, NJ. Earlier experiments had shown that the then-current techniques for converting from analog to digital were an enormous

Figure 19.1 The Colorado Research Corporation building, in Broomfield, Colorado (1958). Where the first digital television system was developed and manufactured.

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bandwidth expanding exercise and really quite impractical. Under our new Signal Corps contract, we discarded all of them and concentrated on just one that stood out to us as the best for digitizing pictures. It had already been invented and given the name “delta modulation” by F. deJageur at the Phillips Laboratories in Eindhoven, The Netherlands, in 1952 and was being used by them for voice and music recording. This delta coding principle fits picture coding particularly well since only the change in brightness from one picture element to the next (a small number) needs to be transmitted. Earlier straight binary coding techniques required that the absolute brightness value of each picture element be transmitted, and this generates a huge and impractical quantity of data. Not only does the delta coding process minimize the amount of data that needs to be transmitted but, quite fortunately, it also delivers it through a single-channel bitstream in a form that is immediately ready for binary signal transmission. We demonstrated delta coded digital pictures to the Signal Corps early in 1959 and they liked them so well that they immediately asked us to join them in opening negotiations with one of their “customers” regarding the design and manufacture of a digital system for an important Government agency. The request for bid for that special television system received by my new little company was so shrouded in secrecy that only those who had been granted the highest level of security clearance could be brought into any discussion of the matter. It would involve full NSA (National Security Agency) approved encryption of digital television signals, a verified field testing of them, and, finally, the manufacturing of field equipment. Our corporate sponsor would have to agree to such a contract and to accept the high level of security that came with it. Fortunately, they were happy to do it. According to the plan, a master video-telephone station was to be built that would communicate with two slave stations via secure microwave radio links. The master station would be located at the White House in Washington, DC, with one slave station at the CIA headquarters and the other at Camp David. Any station would be able to open up communication with the other two. We were told that President Eisenhower had once mentioned that, “if Allen Dulles [then Secretary of State] ever calls me to push the big red button on Russia, I want to be able to see the expression on his face”!

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So off we went to oblige our Commander in Chief, constructing several sets (and spares) of those unique video-telephone systems. The “key generators,” or encryption computers (per NSA specifications), would be built by another company. To expedite the work, we purchased as much of the equipment racks, power supplies, and standard broadcast studio components as possible from RCA, not knowing that RCA was the “other” company building the encryption computers. When the two systems came together (and mated up perfectly) it gave the appearance that the entire system had been built by RCA. Good old RCA! It took a year-long effort to assemble that “once only” system, which was of considerable size (Figure 19.2). In Figure 19.3, you

Figure 19.2 Military digital television system AN-FXC-3 (ZE-1), built under Signal Corps Contract no. DA-36-039SC-74928 by Colorado Research Corp. and installed in the White House, Washington, DC in 1961.

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Figure 19.3 User terminal with lid in operating position. When lid is retracted, the unit has the appearance of a simple filing cabinet.

will see the desk-side user terminal with it’s viewing lid in the lifted position. The long necks of the CRT display tubes (of those times), were often concealed by mounting the tube vertically and viewing the screen via a mirror in the lid, as we did in this case. The mirror was partially silvered and hid a small vidicon camera in the space behind it. This position gave the camera a good view of the face watching the screen and no one was disturbed by its presence. In order to get the highest possible image resolution into this system, limited as it was by the available microwave circuits, we abandoned the U.S. video standards and dropped to a more efficient square picture (we were only looking at faces). We also dropped to the British standard of just 405 lines in the picture, which seemed enough to satisfy the British public. All this was done to squeeze the best possible picture out of our limited transmission bit rate. In Figure 19.4 you see what the pictures were like before, during, and after the digital processing and encryption. Two video monitors on the equipment rack allowed the operators to evaluate the before and after encryption images. These images remained essentially identical except when the privacy switch was thrown by the user. At that point, the encrypted side would disappear, changing to nothing but “snow.” By this means,

THE BEGINNINGS OF DIGITAL TELEVISION

Monitor view of original picture

Digital picture, just ones and zeros

Recovery before encryption

Recovery after entire process

147

Figure 19.4 Digitalized pictures. Note: The moire patterns visible in these pictures are due to superimposed raster scans that occur in computer processing.

even the local technicians were excluded from viewing sensitive transmissions. The voice channel was arranged to travel as though it was part of the encrypted picture. Before installation of the system could begin, late in 1960, it was necessary to bring the White House Signal Corps people up to date with the new equipment. A training class was, therefore, scheduled for 30 days in June of 1960 at our lab in Broomfield. Since it was impossible for me to take time out to teach this class, I solicited the resources of Purdue University, who supplied a (summer vacationing) Professor of Electrical Engineering, Dr. Gilbert Rainey, whom I could quickly prepare and then turn the job over to. Gill immediately absorbed the many new concepts contained in this complex new communication medium and conveyed them to two dozen exceptionally bright young Signal Corps technicians who were then well equipped to install and take over operation of the system.

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Part of the field testing that took place at our lab involved driving one of the terminals mounted in a military van to various remote locations. The van had roof-mounted microwave dishes and the equipment needed to receive pictures originating from our master station and feed them back to us. One night, we sent the van up to Flagstaff mountain, in Boulder’s city park, high above the town and barely visible by line of sight from the dish on our roof in Broomfield, about 15 miles away. The van patched back a perfect copy of the test pictures we were sending out and, of course, when the crypto “key generators” were switched on, the secure screen changed to pure snow and showed no sign of an image at all. The voice channel did exactly the same thing. We then inserted an attenuator into the microwave circuit to simulate added distance between us and the van and we now saw for the first time the outstanding property of digital television. Not the slightest hint of noise, jitters, or brightness fading could be seen as the signal weakened. When the attenuator approached its limit, the screen went completely black, as if a switch had been thrown! Reducing the attenuator setting brought the picture back again, completely free of noise, dimming, or any other impairment. This is the property of digital television that has led to its permanent popularity. Any current viewer having access to a present-day digital television service should be able to duplicate that early observation. It is unfortunate that our installation of the White House system was not fully completed by the 20th of January 1961, when Ike and Mamie turned the place over to the Kennedys. In a conversation with Ike a few years later, he told me that he was very pleased with the installation and saw how it performed using test pictures, but he never had an opportunity to really use it. The Kennedys probably thought that the video-telephone service they found there was just a standard piece of White House equipment and no comment regarding it ever came from them. The Eisenhowers had background connections in the Colorado area, Mamie having been raised in Denver. A young man who grew up next door to her, Axel Nielsen, became an important Denver businessman and was a great friend of Dwight Eisenhower, whom he had met during the courting years. Many will remember that Ike’s summer “White House,” as it came to be known, was at the Nielsen ranch in Colorado. I had never actually seen the President while we were working in the White House to install the equipment, but I had a star-

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tling experience in 1963 when Axel Neilsen’s secretary called, asking me to be at the company office at two o’clock on a certain Saturday afternoon. She said that Axel would be bringing out the former President, who wanted to talk to me briefly and alone! Of course I was there, proudly working at the company’s new Bendix G-15 computer behind a large window overlooking our small front lobby, a common placement for computers in those early days. The door opened in the silent building and a figure walked in, smallish I thought, but with a broad grin and an outstretched hand, “I’m Dwight Eisenhower” he announced. With shaking knees I took his hand and after some small talk we discussed the White House videophone system described above. He had been greatly impressed with it and thought that he and some of the friends who were with him might want to invest in my new company, Colorado Research Corporation, which I had recently formed; Axel Nielsen was Chairman of our board of directors. The Eisenhower group probably thought that I would be starting the development of a commercial version of the digital television he had seen, and they wanted to help it along. Unfortunately, it was many years too soon to do that, as interesting as the idea was. We were still stuck with vacuum tubes as the basis for any serious electronics at that time and there was no such thing as mass memory, so essential for screening out the vast redundancy of television pictures. Any bandwidth-expanding process (like digitizing) simply could not be considered. Had these things been available, it is likely that we might have finished the twentieth century with a firmly established digital television technology (and I might have become as rich as Bill Gates!). Traveling with Ike that summer afternoon were several of his Republican cronies, among them, Freeman Gosden, the early radio personality who played the part of Amos in the famous “Amos and Andy” series on NBC radio many years ago. As a boy, I was one of its fans, completely ignorant of the programs racial implications. It was just a very funny radio show and I knew every one of the characters. Now, here in my office, sat Amos, never mind that the President of the United States was also there! Ike and the others became shareholders in my little company, even though I couldn’t promise them an early stake in the spectacular future of digital television. Freeman Gosden visited us occasionally in the years that followed and every time he came, word would leak out among our employees that Amos was here. He would always humor them

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with a little skit in the lunchroom using those familiar but now silent voices of Amos, Madam Queen, the Kingfish, and others of that little troupe. As Ike lay dying in his hospital room, our employees sent him a huge get well card in the shape of an elephant, signed by every one. They were proud to receive his acknowledgement and well wishes and saddened at his demise. Through various sources (not particularly reliable) I learned that the White House secure video telephone system stayed in operation for 18 years. It was probably the first practical use ever made of digital television.

APPENDIX

A few pages from a summary report describing the development of the Iconoscope in the early 1930s are reproduced on pages 153–162. The report was written by Dr. Harley Iams (Figure A1), who was one of the principle scientists on Zworykin’s (Figure A2) tube development team at RCA for many years. The last page of his report (Figure A3) shows who the engineers were that kept notebooks and reports of even earlier work. I have brought it forward so that it will not be overlooked.

Figure A1 Harley Iams. Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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Figure A2 The young Zworykin.

Figure A3

CHAPTER TITLE

153

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CHAPTER TITLE

155

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CHAPTER TITLE

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CHAPTER TITLE

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CHAPTER TITLE

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REFERENCES

Albert Abramson. Zworykin, Pioneer of Television. University of Illinois Press, 1995. Kenneth Bilby. The General. Harper and Row, 1985. George Brown. "And Part of Which I was.” Published by himself as Angus Cupar Publishers in Princeton, NJ in 1979. (1100 copies were printed, 100 leather bound and autographed; contact IEEE for availability.) Jennet Conant. Tuxedo Park. Simon & Schuster, 2002. Peter Goldmark. Maverick Inventor: My Turbulent Years at CBS. Saturday Review Press, 1973. Robert Sobel. RCA. Stein and Day, 1986. John F. Welch. Jack, Straight from the Gut. Warner Books, 2001. Vladimir K. Zworykin and George Morton. Television. Wiley, 1940; Chapman & Hall, 1954.

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INDEX

AM radio, 22 American colleges and universities, 2 American Marconi Company, 47 Amos and Andy, 149 Ampex Corporation, 128, 130 Armstrong, Edwin H., 21, 22, 23 AT&T, 47, 49 Automotive controls, 2 Baird, John Logie, 8, 9 Baker, W. R. G., 120 Ballard, Randall, 56, 95 Banca, Charles, 54 Bardeen, John, 3, 24 Baruch, Bernard, 114 Baudot, J. M. E., 140 BBC (British Broadcasting Corporation), 9 Bell, Alexander Graham, 5 Bell Laboratories, 3, 24 Bell System Technical Journal, 3 Bedford, Al, 56, 107, 108, 111, 130 Behrend, Bill, 122 Beverage, H. H., 62 Black-and-white screens, 2 Blacker-than-black picture synchronization, 43 Brattain, Walter, 3, 24 Braun, Karl Ferdinand, 13 Braun tube, 13 Brown, George H., 62, 116, 126 Bube, Richard, 71

Busch, Hans, 28 Business machines, 2 Camera disk, 8 Campbell, Richard, 55 Carlson, Chester, 63 Cathode ray display tube (CRT), 28, 32, 43, 77, 84, 86, 95 CBS (Columbia Broadcasting System), 45, 49, 77, 82, 108, 109, 110, 113, 114, 115, 117, 118, 119, 120 Chevalier, Pierre Emile Louis, 49 Colonial Theater, New York, 122 Color TV hearings of 1949/1950, 113 Color Television War, 82 Color wheel, 118 Colorado Research Corporation, 143, 149 Compatible color, 83 Coy, Wayne, 120 Crooke, Sir William, 12 Cryptographic technology, 141 De Forest, Lee, 9, 19, 20, 21, 115 deJageur, F., 144 Delayed broadcasting, 125 Dieckman, Max, 13, 14, 30 Digital television, 137 Digitalized pictures, 147 Diode tube, 20, 21 Distant electric vision, 5

Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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166

INDEX

drum receiver, 80 DuMont, Allen B., 59, 114 , 118 Earth satellite, 2 Edison effect, 17, 20 Eisenhower, Dwight, 148, 149 Electron gun, 42 Electronic age, 2 Electronic amplification, 20, 29 Electronic color television camera, 101 Electronic technology, 2 Electronics magazine, 3 Engstom, Elmer W., 55, 60, 91 Entertainment products, 2 Epstein, David W., 95, 96 Essig, Sanford, 34 Evans, John, 62 Fabray, Nanette, 117 Farnsworth, Philo, 5, 31, 37, 39, 38, 60, 66, 89 FCC (Federal Communications Commission), 82, 106, 108, 109, 110, 114, 115, 116, 120, 122, 123 Felix the cat, 10, 11 Field-sequential color camera, 79 Field-sequential color system, 108, 110, 117 Fink, Donald, 120 Fleming, John Ambrose, 18 Fleming diodes, 24 Fleming valve, 19 Flight safety devices, 2 Flory, Leslie, 33, 34 54 Flory, Robert, 33, 36 Flying-spot scanner, 88 Forest "audions", 24 Forgue, Stanley, 71, 75 Francis, Harding, C., 44 Frequency, 23 Frequency modulation (FM), 23, 24 Fredendall, Gordon, 81, 130 Fyler, Norman, 94 Fyler-style faceplate, 94 GE (General Electric Corp.), 10, 33, 47, 50, 59

George, Roscoe, 41, 44 Goldmark, Peter, 77, 118, 120 Gosden, Freeman, 149 Goldberg, Ed, 106 Goodrich, Robert R., 71, 75 Grigsby-Grunow Company, 41 Haloid Corp., 64 Hammond, John Hayes, 59 Ham radio, 1 Hanson, O. B., 130 Hazeltine Laboratories, 59, 120 Heim, Howard, 41, 44 Hell, Rudolf, 30 Herold, Ed, 93 Hertz, Heinrich Rudolf, 107 High-sensitivity radio receiver, 23 Hillier, James, 62 Home appliances, 2 Houghton, Bill, 106 Howarth, Frank, 81 Howath, Walt, 119 Iams, Harley, 33, 65, 151 Iconoscope, 15, 31, 34, 35, 36, 50, 53, 54, 57, 65 Image dissector, 30, 37, 38, 39, 40 Image scanning concept, 7 Image-orthicon, 66, 67, 68, 101 Institute of Electrical and Electronics Engineers, 3 Institute of Radio Engineers, 3 Interstate Commerce Committee, 115 Jenkins, Charles Francis, 9, 10 Johnson, Senator Edwin C., 115 Johnson, John, 119 Kell, Ray D., 52, 56, 77, 88, 115, 120, 130 Kihn, Harry, 122 Kinescope, 28, 49, 51, 125 Korean War, 119 Kukla, Fran, and Ollie, 116, 117 Large-screen projector, 98 Law, Harold, 68, 91, 93 Law, Russ, 91, 93 Leverenz, H. W., 95, 97

INDEX

Leyton, Eric, 130 Light converter, 9 Light storage, 30 Light storage type of tube, 33 Lind, Anthony, 130 Line-sequential system, 110 Loughlin, Bernard, 120, 121 Luther, Archer, 130 Masterson, Earl, 127, 128, 129 Maxwell, James Clerk, 18 Mechanical scanners, 8, 29 Medical instruments, 2 Miniature image orthicon camera tube (MIMO), 64 Morrison, Wendell, 122 Murray, Albert F., 59 National Television System Committee (NTSC), 82, 120, 124 NBC, 113, 114, 116, 117, 118, 123, 127, 128 Nielsen, Axel, 148 , 149 Nipkow, Paul, 6, 7, 29 Nipkow disk, 32, 86 Nipkow film scanner, 43 NSA (National Security Agency), 144 NTSC Color Television System, 121 Oglobinsky, Gregory N., 33, 55, 56 Olson, Harry F., 62, 126 Orthicon, 65, 66 Orthiconoscope, 65 Paley, William, 49 Parr, Jack, 110 Personal computers, 2 Philco, 59, 60, 120, 121 Philips of Eindhoven, 73, 75 Photocell, 29, 86 Photoelectric cell, 9, 29 Photoemission, 33 Photo-pickup camera, 13 Photosensors, 32 Plumbicon, 73, 75 Polarizing film, 80 Portable telephones, 2 Pritchard, Dalton, 121, 130

167

"Princeton" camera, 102, 113 Purdue Research Foundation, 41 Purdue University, 41 441 line all-electronic station, 44 60 line experimental TV broadcasting station, 41 TV transmitter building, 45 Radar, 1 Radio, 1 Radio signals, 21 Radio Television Manufacturers Association (RTMA), 120 Rainey, Gilbert, 147 Ray beam, 13 Rays, 12 RCA (Radio Corporation of America), 10, 14, 23, 31, 33, 34, 35, 36, 41, 43, 45, 47, 48, 49, 50, 59, 60, 61, 62, 63, 64, 66, 68, 70, 72, 73, 75, 77, 79, 80, 81, 82, 87, 91, 93, 94, 96, 98, 99, 105, 106, 108, 109, 110, 111, 113, 114, 115, 116, 119, 121, 123, 124, 126, 127, 130, 141, 145 laboratories division, 59 Princeton, New Jersey, lab, 61 World War II, 62 RCA Color Television System, 121 RCA Review, 3 Reddick, Joe, 122 Regenerator, 22 Registration, 83 Rice, John, 143 Rose, Albert, 65, 66, 68, 71 Rowe, W. E., 94 Rozing, Boris L'Vovich, 13, 14, 32 Sarnoff, David, 23, 34, 47, 48, 49, 57, 72, 81, 85, 86, 96, 99, 105, 121, 124, 126, 128 Scanner, 11 Scanning, 33 Scanning "lines", 7 Schlessinger, Kurt, 45 Schroeder, Al, 35, 81, 84, 86, 89, 90, 91, 92, 93, 95, 97, 103, 115, 130 Science, 3 Señor Wences, 99

168

INDEX

Sensitive camera tubes, 65 Shadow mask, 92, 93 Shadow mask color kinescope, 90, 93 Shadow mask picture tube, 89 Shannon, Claude, 105 Shockley, William, 3, 24 Siegmund Loewe Television Company, 46 Signal Corps, 142, 143, 144, 147 Silicon wafer, 4 Simplex video recording project, 130 Simplex system, 126 Simultaneous TV system, 110 Simultaneous color television projector, 85, 88 Small screen, 2 Smith, David, 120, 121 Smith, L. P., 62 Smith, Roland, 71 Society of Motion Picture and Television Engineers, 3 Space probe, 2 Spradlin, J. D., 123 Sterling, George, 116 Stereo sound, 2 Storage, 30 Swinton, A. A. Campbell, 5, 6 Sylvania, 59 Synchronous demodulator, 109 Sziklai, George, 98 Technicolor, 78 Television receiver-projector, 96 Thomas Edison, 5, 17 Thompson, Browder J., 56 Thomson, J. J., 11, 12, 19 Three-tube color monitor, 100 Tibanyi, Kalman, 31 Tilstrum, Burr, 116, 117 TK-40, 102 TK-41, 123 TK-44, 123 TK-45, 123

TK-46, 123 TK-47, 123 Tolson, W. A. "Doc", 56 Transistor, 3, 4, 24 Tri-color camera, 98 Triniscope, 100 Triode, 20 Triple image-orthicon, 98 Truman, Harry, 114 U.S. Signal Corps, 141 U.S. TV standard, 82 Vacuum tube, 4, 17, 24 Vance, Arthur, 33, 54 Verne, Jules, 5 Victor Talking Machine Company, 48 Video broadcasting systems, 1 Vidicon, 68, 69, 70, 72, 74 construction and operation, 73 Watson-Watt, Robert, 96 Wendt, Carl, 95, 97 Western Electric Co., 49 Westinghouse Electric Company, 27, 33, 47, 50 Weimer, Paul, 66, 68, 69, 71, 75 Wiener, Norbert, 105 Wolf, Irving, 62, 63 World War II, 70 Wright brothers, 5 Xerography, 63 Young, Owen D., 47, 48 Zenith, 59 Zworykin, Vladimir K., 13, 5, 13, 14, 15, 25, 26, 27, 28, 30, 31, 32, 33, 34, 36, 49, 50, 51, 55, 59, 62, 65, 70, 71, 85, 98, 151, 152 Zworykin camera tube, 31

ABOUT THE AUTHOR

Richard C. Webb was associated with RCA from 1939 through 1954, first as a research fellow at Purdue University and from late 1945 as a staff research Engineer at the RCA Laboratories in Princeton, New Jersey. Webb graduated in physics from the University of Denver in 1937 and trained in electrical engineering at Purdue University, receiving an MSEE in 1944 and PhD in 1951. He returned to academic life at the University of Denver in 1954 but was often drawn away by industrial challenges. He was the founder of three small companies involved in a wide range of electronic technologies from space vehicle test instrumentation to early forms of computers. He was one of the first to place oil well drilling rigs under computer control. He was granted 29 patents. He was a pioneer in the development of digital television. Tele-Visionaries: The People Behind the Invention of Television. By Richard C. Webb Copyright © 2005 the Institute of Electrical and Electronics Engineers, Inc.

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TELE-VISIONARIES

As an adjunct faculty member of the University of Colorado, he taught one early morning class in electronics every semester for 20 years. He served on several science and engineering boards and panels, receiving honors from RCA and other industry sources including the Fellow Member award of the IEEE in 1956. He was an officer in the local IEEE chapter as well as the Western Electronic Manufacturers Association (WEMA). He received the “Outstanding Electrical Engineer Award” from Purdue in 1992 and an honorary Doctor of Science degree of from the University of Denver in 1996.