Electronic Design
Robert H. Anderson: Putting The “Storage” In Oscilloscopes

Robert H. Anderson: Putting The “Storage” In Oscilloscopes

Anderson (2011)

Scope displays of this nature seem like a given to us today. Yet, old-timers will remember a day when the cathode-ray-tube (CRT) displays of oscilloscopes were not so capable. In fact, to capture an image of transient events, the only viable option was to employ an oscilloscope camera to take a photograph of that transient. Getting that image could be an arduous process, involving much wasted time and film.

All that was changed by a soft-spoken physicist named Robert H. “Bob” Anderson, who joined Tektronix in 1959 to work with a research group led by Dick Ropiequet. Some seven patents later, Bob left Tek in 1969, but not before he’d invented what Tektronix termed the direct-view bistable storage CRT, a device that would result in a new category of oscilloscope (the storage oscilloscope) and helped build Tektronix into a test-industry giant.

The Road To Tek

Bob was born on March 27, 1925, in Jersey City, N.J., and grew up in nearby West Orange. His father, a civil engineer, helped design the foundation of New York’s Chrysler Building. By the time he was about 13 years old, Bob Anderson knew he wanted to be a “technical guy.” His older brother’s copy of Alfred Ghirardi’s Radio Physics Course Book firmed up his interest in technical topics.

Bob earned a degree in engineering physics from Lafayette College in Easton, Pa., which was one of only four schools in the United States offering that degree at the time. “It’s a physics degree where instead of taking humanities as electives, you take engineering courses,” says Anderson.

His first job out of school was at RCA Laboratories in Princeton, N.J., where he apprenticed in a tube assembly service group. Later, he worked on photomultiplier tubes with George Morton and Vladimir Zworykin, garnering two patents and inventing the first very small photomultipliers, which were intended to go down 1.125-in. inside-diameter oil well pipes.

“Now, what was interesting was before that, they used it in the first automatic headlight dimmers, which were in a little pod mounted on the dash,” says Bob. “I had the fun of seeing these cars go by with my invention in it.”

Anderson moved on to a job at Hughes Aircraft in Los Angeles at a time when many “technical guys” were heading west. At Hughes, Anderson had his first exposure to the primitive storage CRTs of the day. But when Hughes moved to Oceanside, Bob didn’t want to follow and landed a spot in Ropiequet’s research group at Tektronix.

The Storage Problem

“At Tektronix, I saw that bistable display tubes would be a natural for oscilloscopes because they didn’t need grey shades,” says Bob. “I thought I could come up with something simple. So I tried three different structures that came to mind, and the third one worked. The first two stored the trace but weren’t good enough.”

Designing a storage tube that combined a simple structure with good brightness, contrast, resolution, and uniformity was the challenge that Anderson assigned to himself. “The nature of the challenge was a structural problem,” says Anderson.

“I was after great simplicity. I knew that the basic physics that would make it work was secondary emissions. Then, there’s the problem of how to collect the secondary emissions. I was working on a tube in which I was using dot patterns,” he says.

“I knew the fundamental problem was that a stored trace would tend to spread or shrink on the tube’s surface. So you had to do something to stop that from happening. I was working with a polka-dot pattern so that the stored trace could not jump from one dot to another,” he says.

“Then, it was hard to make that dot pattern without having some scattered phosphor particles in between the dots,” he explains. “The phosphor particles were storing the trace, but they were too dim. I felt that by just making scattered particles without the dots, I would have at least a dim storage tube.”

With the addition of more phosphor, Anderson expected his CRT to fail when the particles touched each other and made a continuous layer. To his surprise, however, the tube worked and proved optimal when the phosphor layer was applied not in a dot pattern but in a scattered fashion in which the phosphor particles are irregular in shape and touch each other randomly.

 

The “eureka” moment came with a particular experiment in which Anderson was initially very disappointed: The tube did not work at all. ”I thought, ‘maybe I should try a higher voltage.’ I thought I might destroy the storage target. But I figured it was already destroyed, so I had nothing to lose. I turned up the voltage and it worked.”

Bob recalls the process of inventing the storage tube taking about five months, with the result being a small-diameter tube with rather primitive front wall bands. It took further applied research to arrive at a good quality 5-in. storage tube. “It was great fun to demonstrate because it had no internal storage target, which previous tubes had used,” says Anderson. “You could see in one side of the empty tube and out the other.”

Bob was assigned U.S. Patent No. 3,293,473 for a “Thin, Porous Storage Phosphor Layer” on December 20, 1966. This is the basic patent on the bistable storage target. Earlier, he’d been granted patents for the tube as a whole. (For a full, and vintage, explanation of the inner workings of Bob Anderson’s storage CRT, see The Storage Story from the Spring 1966 issue of “Tek Talk,” an internal journal.)

“Tek was a little slow to pick up on (the storage CRT) because nobody had asked for it. It wasn’t an assigned project,” says Anderson. “I had been given great freedom to work on what I wanted to, which was very unusual. Well, Tek did eventually pick up on it and put it in an instrument, which was immediately successful.”

That instrument, the Type 564 storage oscilloscope launched in 1963, was a 10-MHz instrument that competed with the Hughes Aircraft Model 104 oscilloscope, which was based on the Memotron storage tubes Anderson had worked on earlier at Hughes. “The Tek tube actually put the Hughes Memotron oscilloscope line out of business. You could buy a whole Tek scope for the price of the replacement tube for the Hughes,” says Bob.

A follow-on invention to the direct-view bistable storage CRT was the split-screen storage tube. “It’s nothing more than a scratch across the backing plate,” jokes Anderson. “You could write a trace on each half of the screen and separately erase them. This way you could compare two waveforms.”

Howard Vollum, Tektronix’s co-founder, saw Anderson’s demonstration of the split-screen tube and was determined to get it into production by 1966’s Wescon Show. The result was the Type 549, Tektronix’s second-generation storage scope with split-screen storage and a 30-MHz bandwidth.

“From there, we went to plug-in-type instruments, and then to wide-bandwidth instruments,” says Bob. “Then one day, a manager from the business office came around to see my demonstrations. He said, ‘You know, we’re going to have to build a new building to make these additional tubes.’”

Anderson’s storage tubes were about to find their way into large-screen display monitors (types 601 and 611) and the 4000 series of computer terminals. Tektronix did indeed expand its manufacturing operations expressly for building all the equipment that housed Anderson’s bistable storage CRTs.

Life At Tek And After

Anderson vividly recalls the experience of working at Tektronix in the early 1960s. “It was very informal,” he says. “People went around sloppily dressed. They had a competition on some occasion where many people grew beards. No one wore suits very much at Tek. Everybody was accessible. You could go talk to Vollum or (cofounder) Jack Murdock. And they would come around to see what your latest results were.”

Despite the freedom he’d been given to invent the bistable storage CRT, Anderson has some interesting observations about the culture at Tektronix in his day.

“Tektronix wasn’t comfortable with the words ‘applied research,’” says Bob. “They liked the result, but they didn’t always like the process. They didn’t believe in designating some people as research physicists. They felt that good ideas would come from everybody. In fact, Howard Vollum once said to me, ‘what one man doesn’t invent, another man will.’ And I immediately said to him, ‘But that other man might be working for Hewlett-Packard.’”

Anderson left Tektronix in 1969 and went on to a career in optics with stints at the Illinois Institute of Technology Research, Zenith, and Litton Data Systems, where he garnered nine more patents in optical pattern recognition (see “Bob Anderson’s Path To Invention”).

Anderson retired from Litton in 1988 and stays busy these days with exercise, both physical and mental: the former consisting of weight lifting and walking; the latter comprising writing software routines for factoring very large numbers, which are the product of two prime numbers.

“I also went back to school and took music courses and have an elaborate setup of computer-controlled music synthesizers,” says Anderson. “My one other hobby is the inscrutable stock market. At Tek, I used to tell people that my hobby was studying the effect of low humidity on the laws of probability, for which I would do my research in Las Vegas.”

Acknowledgement

The author is indebted to Tektronix and to the VintageTek Museum for their assistance in compiling this article.

 

Bob Anderson’s Path To Invention

In the course of his long career as an inventor and research physicist, Bob Anderson collected wisdom on the process of invention, which he would like to pass on. “I have a very specific philosophy on how to invent and how to teach people to invent,” he says.

“First of all, there is a price of admission, which is you have to want to invent and to be an inventor. Then you need some degree of education, intelligence, and experience. And I would hate to put numbers on it, but you usually don’t get there in your first three years out of school. You have to do your apprenticeship. Frequently, the self-educated guy without a degree can be just as good an inventor or better, if he really has the education.

“Then comes the technique, and there is a very special technique. It starts with extreme problem sensitivity. When you go into a grocery store and your cart is jammed up in another one, some people just say, ‘damn this thing’ and go get another one. Another guy says, ‘they ought to fix this.’ But the third guy says, ‘I ought to fix this.’ You need to be sensitive to every problem that you hear about.

“After problem sensitivity, it’s crucial to work on many problems. You need a notebook full of dozens of things that you recognize as worthwhile problems. And when you first recognize the problem, you need to sit down and scribble drawings for at least half an hour trying to invent something. You will typically fail. But every month or so you go back to your list and try again and again. Then some day, you’re thinking about something else and you see the answer to one of your many problems.

“So applied research is high risk, high failure, and high return. It takes a certain personality that is impossible to discourage. You have to be as unsinkable as a rubber duck.”

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