Oral-History:Shigeru Nakajima

About Shigeru Nakajima

Shigeru Nakajima was born in Japan around 1910. The son of a schoolmaster, he attended Wasada University and studied power engineering. Though he graduated during the Great Depression, he was able to secure a job with JRC Company.

Nakajima discusses his work with magnetrons for communications and medical applications. In the late 1930s, he took a position with Telefunken of Berlin to work on phototubes, magnetrons, and vacuum tube getters. During World War II, Nakajima and his brother worked in Germany and Japan on such projects as military radar, the atom bomb and a ray weapon. In the post war period, JRC experienced materials shortages and was restricted to non-military markets. However, the company developed new applications including microwave communications and electronic fish locators for commercial fishing.

About the Interview

SHIGERU NAKAJIMA: An Interview Conducted by William Aspray, Center for the History of Electrical Engineering, May 26, 1994

Interview #212 for the Center for the History of Electrical Engineering, The Institute of Electrical and Electronics Engineers, Inc.

Copyright Statement

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It is recommended that this oral history be cited as follows:

Shigeru Nakajima, an oral history conducted in 1994 by William Aspray, IEEE History Center, New Brunswick, NJ, USA.

Interview

Interview: Shigeru Nakajima

Interviewer: William Aspray

Date: May 26th, 1994

Place: Tokyo, Gakushi Kaikan, Conference Room No. 309, University Alumni Association Hall

[Note: Aspray’s questions are spoken in Japanese by a translator, and Nakajima's replies are spoken in English by a translator. Dr. Yuzo Takahashi of Tokyo University of Agriculture and Technology, who reserved the room is also present. Dr. Takehiko Hashimoto of the University of Tokyo is also present, also Mr. Naohiko Koizumi of Futaba Corporation.

Family Background and Education

Aspray:

Dr. Nakajima, I am going to ask you to tell your life story in your own words. I may occasionally ask you a question to follow up on something you've said, but I'll let you direct the flow of the conversation, if that's okay with you.

Nakajima:

Okay.

Aspray:

Could you begin by telling me about your childhood and your education?

Nakajima:

I was born in a fishing village in the Chiba prefecture, Onjuku, and my father was the schoolmaster of the primary school. My father was very devoted to education, and he established a new high school for women in Japan in the fishing village.

Aspray:

Because of your father's profession, was it expected that the children would get a good education and go to university?

Nakajima:

Yes, I have three brothers and four sisters, and just three of four brothers (including me) and two of four sisters went to the university. My elder sister went to a Japanese Women’s University, went into a mathematics department, and became a teacher of mathematics of women’s high school. The youngest of my elder brothers is the late Dr. Yoji Ito who passed away at the age of 53.

Aspray:

Were you a good student when you were growing up? What did you want to do as an adult? What were your aspirations for your adult life?

Nakajima:

I was not an excellent student. I was leader of the class at middle school but failed to enter the Imperial University of Tokyo, so I had to go to Waseda University, a private university and the best private university.

Aspray:

What did you want to do when you were growing up?

Nakajima:

In high school I already wanted to become an electrical engineer.

Aspray:

I see. What was taught as part of your course of study at the university?

Nakajima:

I went into the power engineering department because it also offered communications. If I went to a communications department, I couldn't get a national license, national license for electrical power engineers so I had to go into power engineering. Privately, I was already studying communications.

Aspray:

I see. That was an important thing to have for one's future career? Is that right?

Nakajima:

Yes.

Toshiba Patent Monopoly and JRC

Aspray:

You graduated in 1930. That's just about the time, at least in the West, that the Depression was coming. Had the Depression hit in Japan yet, and was it difficult to find jobs in Japan when you graduated from college?

Nakajima:

Yes. The influence of the Depression was deep. Almost two thirds of the graduates could not enter a company, and my advising professor recommended me to the Hitachi Company. Hitachi didn't have a department of vacuum tubes, so I declined and stayed in the engineering department for about one year. About that time Toshiba and NEC declined to give me a job, and JRC accepted.

Aspray:

Toshiba did not offer you a job?

Nakajima:

No, but at that time Toshiba had bought the Langmuir patent for the hard-valved electron tube and almost dominated the manufacturing of those vacuum tubes. At that time radio broadcasting became very popular, and Toshiba offered only expensive vacuum tubes, so a radio set became more expensive if you bought a Toshiba tubes. Because of the radio boom, lots of factories (more than twenty) were building; and they were producing less expensive vacuum tubes. At that time JRC was planning allowed by Toshiba to produce the amount of seven hundred thousand yen of vacuum tubes, but instead Toshiba could use all the JRC patents, cross-licensed: it was because of the Langmuir patent whose expiring date was extended. Toshiba required a much higher patent royalty from some small vacuum tube manufacturers in Japan. Toshiba had the right over the patent of the GE. So instead of GE, Toshiba wanted to get the patent royalty from various small vacuum tube manufacturers at the time.

Aspray:

I see. Toshiba had bought the patent rights, and they were going to exercise all the control over it that they could possibly get.

Nakajima:

Yes. But I was very glad to know that I need not study that old Langmuir patent, and at least I could study more new technologies about the electron tube.

Aspray:

Okay.

Nakajima:

At that time I started to study Barkhausen-Kurtz oscillator and magnetron, but I was not sure at that time that such things would become useful for practical use, so I wanted to study microwave tubes, very high frequency tubes.

Aspray:

This was in the 1930s still? Soon after you had joined JRC?

Nakajima:

Yes, I supposed the Langmuir patent would expire in the near future.

Aspray:

Yes, I see.

Microwave Medical Device

Nakajima:

In 1935, or so, I was somewhat ill, something like pleurisy. I was acquainted with a medical doctor, and we became lifelong friends. He gave me the knowledge of Germany. In that country there was some electromagnetic therapy in practical use. He asked me, "Can you make such equipment?" I answered, "Yes, of course." He was a Doctor of Medicine and an assistant professor at the Imperial University of Tokyo. He told me how to use a microwave to heat up muscle [tissue], to use in therapy sessions.

At that time (in 1935) the Langmuir patent had already expired, so JRC did not have to pay any royalties to Toshiba. There were excessive of the therapy equipment orders compared with production capability and JRC could get a lot of money for orders of the apparatus of the wireless communication equipment.

Aspray:

Just for this medical apparatus?

Nakajima:

Yes, medical.

Aspray:

There was such demand for this medical product that it was at least as successful as the military and marine products that were being developed by the company? Is that the thrust of this?

Nakajima:

The rate of profit for the medical product was very high, but the total sales of the product was very low, compared with that of the military and marine products.

Takahashi:

JRC had a good connection with the military authority because JRC was one of the most important military suppliers. It was also because a key person of the Navy was his elder brother, Yoji Ito.

Nakajima:

As JRC got a lot of money, the president of JRC at that time asked me to take some three years' vacation, or so, to go to some foreign company that I liked. I thought that I would go to Germany at that time because Telefunken already had some patent relations with JRC. But the president opposed my going to Telefunken because Telefunken was under the control of the German military and Telefunken would decline to show the technology. Anyway, I insisted on going to Germany.

Aspray:

So the three years were as a reward for getting this very profitable order?

Germany and Telefunken

Nakajima:

Yes. The negotiation with Telefunken was not easy. It took about three months, but eventually I was permitted to go to Telefunken.

Aspray:

In Berlin?

Nakajima:

Yes. 1937. That was maybe three or four years before the start of World War II.

Aspray:

Not that much before, because in 1938 Germany was already moving into countries.

Nakajima:

So in 1937 maybe some connection between Japan and Germany existed. The preparations for war were underway. I studied at Telefunken for a year and a half learning about transmitting vacuum tubes for example, zirconium getter.

Koizumi:

Getter means gas-absorbing materials in a high vacuum envelope.

Nakajima:

That was new technology for Japanese vacuum tube manufacturers. I brought it back from Germany. Until 1965, Japanese vacuum manufacturers used dead-copy of my getter.

Waseda University & Tube Research

Aspray:

Before we go on, could I ask you a couple of questions about your electronics background from a little earlier in your life? There are two questions. Could you describe in a little more detail what went on at the Kodakura research laboratory, at Waseda University and what you did and learned there?

Nakajima:

I studied photo tubes in Waseda after graduation from university and before joining JRC. Just after I joined JRC I was in charge of the oscillation tube, or magnetron, or the ultra-short-wave tube. As for the magnetron, it was suggested by Kiyoshi Morita of the Tokyo Institute of Technology. (Morita was the advisor of Heitaro Nakajima when H. Nakajima wrote his graduate thesis.)

Koizumi:

Just after he joined JRC.

Aspray:

I see.

Koizumi:

Morita, assistant at that time, at the Tokyo Institute of Technology, was preparing his doctor's study. His topic was the short-wave tube. He ordered JRC to make a prototype tube or experimental apparatus. The magnetron. He became later professor of the Institute.

Aspray:

During the 1930s, when you were studying these tubes, how was knowledge passed? Was there available literature from other countries? Was there another group of people within Japan that was studying these? How did you learn about these things?

Nakajima:

I'm sorry; no information exchange existed among the companies in Japan. Toshiba was the only one tyrant.

I’ll explain the reason. There is a book titled The History of Electron Tubes published in 1987 written in the Japanese language. I am one of the co-authors. At the time of making this book I asked the Toshiba people why Toshiba had no patent concerning electron tubes. JRC had so many original patents. The answer was that the vice-president of Toshiba came from GE, and Toshiba people were not allowed to make such new technology as vacuum tubes.

Aspray:

Is there a journal literature in English or German? If there is, is it available? If that journal literature is available, does it tell you the things that you need to know, or do you need to have know-how about building these tubes that wouldn't be in the scientific literature? Those are the kind of things that I would like to know.

Nakajima:

Some journal literature was available to the JRC Company. I read German journals everyday. Of course, some books from the United States would be available at that time, but I already forgot them.

Magnetron Development

Aspray:

Maybe we should continue then with the story.

Nakajima:

Morita made a drawing of the magnetron and asked me to have JRC build it. I was very interested in such things, and also my brother Yoji Ito showed interest. He was in a Naval Research Institute. He was studying the Kennelly-Heaviside layer. He thought that some ultra high frequency, such as radar, would be useful because some reflection of electric wave would be possible.

Aspray:

Yes, I see.

Nakajima:

So at that time Doctor Ito used to ask me for a weekly report. In 1934 he took leadership of the laboratory of vacuum tubes in the Naval Research Institute. At that time a special research contract was made between the Naval Research Institute and the JRC Company. My elder brother was not satisfied to invite only me, and he took some five or six vacuum tube workers from JRC to the Naval Research Institute at Meguro, Tokyo to build a group for manufacturing.

Aspray:

So the two groups were working independently.

Nakajima:

But not completely independently; very close coordination, and a very dutiful brother. Some differences though. At that time in my magnetron laboratory there were maybe three hundred persons — only for the magnetron. It was maybe the biggest magnetron factory in the world. At the Naval Research Institute, they discovered a special construction in which the frequency is very stable; the stability is very good. That knowledge was fed back to JRC, so there was big and quick progress.

Aspray:

Yes, I see.

Nakajima:

Finally JRC made such a device in 1939. It was a single-phase oscillator with ten-centimeter wavelengths. I believe this was the first one in the world and it had a five-hundred-watt output.

Aspray:

So this was the first one with that high an output?

Nakajima:

Yes. It was also water-cooled.

Nakajima:

At last the power went up to some hundreds of kilowatts or so. During the Second World War, many naval warships installed radar using our first developed water-cooled magnetrons.

Nakajima:

That was earlier than the United States.

Aspray:

Yes.

Radar and the Japanese Navy

Nakajima:

But at that time there were so many opposite opinions in the Navy on using such radar. The reason why: with this thing and in a dark night with a light on, one could find a robber.

Takahashi:

Maybe I should try to put it another way. The Japanese military authority, the Navy also, relied upon the optical weapons. Our optical technology was good, and they say that the Japanese have excellent eyes for watching with the optical aided tool (telescope, etc.). This was the main tool of the Navy, and they didn't appreciate the meaning of radio weapons. They looked down with scorn at such an idea. Yes, very skeptical.

Aspray:

Very interesting.

Nakajima:

Some top department of the Navy believed that radar was of no use; very strange. They didn't believe in the electronics technology, I think. They didn't permit us to use the precious metals for the magnetron, such as cobalt for use in magnets.

Aspray:

The Navy wouldn't permit it?

Nakajima:

No. Yoji Ito's group made about one hundred radars. They were not installed to big battle ships, but only small ships.

Aspray:

I see, so they were putting them into small ships that might have been fishing vessels.

Nakajima:

Yes. At the last stage of the naval war in the dark night, the Japanese were worst hit by the United States. There must be some radar.

Aspray:

That is what made the Japanese Navy believe in radar? Is that what you are saying?

Nakajima:

Right. So in late 1943 or so, the Japanese Navy began to think there must be radar in warships. At that time JRC people were obliged to make radar devices but also the Navy must install the devices, so, for example, Sogo Okamura and Seibun Saito were ordered to —

Koizumi:

Okoshi's teacher.

Nakajima:

And also Ito could not continue their research.

Aspray:

So not only did you have an urgent plan to build all this equipment, but there was an urgent plan to get it installed. You even had to take away very good researchers to do this job?

Nakajima:

Yes, right. You know, the vessels were not in Japan, but the place was just fighting. The authorities dispatched not only the operators but also excellent researchers to such places to install them.

Aspray:

Yes. I see.

Nakajima:

The Japanese Navy installed radar earlier than the USA. Midway through the operation, the Japanese Navy was very heavily damaged. But at that time, in our northern sea area, the Japanese Navy dispatched two or three ships, on which was installed microwave radar and also an ultra high frequency radar.

Takahashi:

Do you know the history, the story of radar? Ships with radar were very successful in retreating from the Aleutian Islands. There were many troops on each small island, and they would go back to the ship and return.

Aspray:

Yes.

Takahashi:

It was very successful, but Midway.

Aspray:

Another story.

Nakajima:

In the Aleutian area there was no United States Navy. But on the return to Japan, there was a very hard storm, and every ship was.

Aspray:

Scattered.

Nakajima:

At that time microwave radar was very useful to confirm which ship —

Aspray:

Which ship was where?

Nakajima:

The shipmasters confirmed the usage of radar, but at the time, still some top departments of the Navy didn't think that the radar was useful. General Isoroku Yamamoto personally asked my elder brother Ito to make an entirely new weapon. Without it, it would be impossible for Japan to win the war.

Aspray:

This was when? What date?

Nakajima:

April 1941.

Aspray:

That's interesting.

Wartime Weapons Research

Nakajima:

Ito thought of the atom bomb. He frequently went abroad, so he knew that the U.S. had forbidden in 1939 the export of uranium ore. So he realized that the U.S. must have surely been planning to develop the atom bomb. He was thinking that Japan had to do something to prepare for this. In January 1940 he was sent to inspect war-preparations in Europe.

Takahashi:

Doctor Ito got a Ph.D. under Professor Barkhausen in Dresden. Ito had very good knowledge of the German language. For example, he translated a tale for children from German to Japanese.

Nakajima:

He was very fluent, and could get the kind of information the German army was very reluctant to reveal. This included their top-secret projects such as the Wurzburg radar and so on. But he was scheduled to stay just for two months. He was blocked because of the war, so he had to take ten months to just return from Germany to Japan.

Aspray:

The long way around.

Nakajima:

Around South America. There was no transportation connection between Germany and Japan.

Nakajima:

Ito finally came back to Japan and tried to prepare the radar as well as the atom bomb. He couldn't get information about the atom bomb in Germany, but he discussed it with the physicists (Professor Nishina, etc.) in Japan. There was a meeting and finally the famous Japanese physicists decided that Japan could not develop the atomic bomb, and also that in the United States it would be impossible to develop the atomic bomb during war time. My brother Yoji Ito told me personally several times that the United States surely knew how to make the bomb.

The next story is about the destructive ray. The JRC started developing bigger, higher power magnetrons at the laboratory in 1941, trying to kill a rabbit.

Aspray:

Kill a rabbit?

Nakajima:

Kill a rabbit, yes. Successfully. Because General Yamamoto was asking Ito to make a new weapon to win the war, Ito was thinking about making a several thousand-kilowatt magnetron. With this microwave he could hit the airplanes and make the engine dysfunction somehow. He was thinking about it. So he established a new laboratory, at Shimada in Shizuoka Prefecture, and gathered lots of famous physicists, such as Tomanaga, Kotani, to develop this kind of high-output magnetron. But he was not very successful. The biggest magnetron they developed was from JRC. One of four company men, Sozaburo Yamasaki, made a magnetron of 20 cm wavelength, having the output power of 100kW. A more powerful magnetron having the output power of 1000 kW was undergoing trials as of August 1945.

In 1953 I traveled around the world without a translator. At that time I went to London, and at the museum I found exactly the same thing, which was explained as: "This was invented by some Birmingham University people in 1940." 1940 was one year later than our invention. When I found this one in the London museum, there was an explanation that this magnetron led to Allied victory for the Second World War. After that, a symposium was held in England by IEE, but at that time there was no exhibition of this magnetron. I felt very strange — why was that thing not then exhibited? That was 1985. At that time there were so many kinds of parts exhibited in many rooms, but there was no exhibition of this magnetron. I felt very strange and asked everybody, but there was no answer. After that, when I sat alone, taking some tea, one old gentleman hit my shoulder by the hand and told me, "Your magnetron must have been stolen by the English King." That was an interesting thing.

Postwar Microwave Research

Aspray:

Maybe we should turn to the post-war period?

Nakajima:

In the post-war period the general headquarters of the Occupation Force was very stringent in restricting what should be manufactured. In the case of the JRC Corporation, radio receivers and medical equipment could be produced, but not transmitters.

Nakajima:

But three or four years’ later, wireless equipment for marine use was permitted. Therefore, we could produce transmitting vacuum tubes, so we could make a profit from that. Getter is gas-absorbing material in the vacuum tube to keep a high vacuum. At that time JRC was almost the only producer for that. Its market share was ninety-eight percent or so.

Aspray:

In Japan?

Nakajima:

Yes. We had the orders also from the United States. In one year, two hundred million vacuum tubes were produced in Japan. So we could make money by means of getter production.

Hashimoto:

The difficulty was because of the GHQ, but they could survive because of getter.

Nakajima:

At that time, only the JRC Corporation had microwave engineers. JRC had more than one hundred microwave engineers, and I had to consider what kind of jobs they must be doing.

Aspray:

Because you were now the manager of the research and development division?

Nakajima:

Yes. I thought that if the microwave was used, multiple communications could be possible: for example, the telephone. At the first stage I considered multiplex telephone transmission by frequency modulation using a variable-frequency magnetron. But instead of frequency- modulated equipment, there was a patent by Professor Nagai of the Tohoku University, called PTM, which is pulse time modulation. We thought this type would be better, so we produced some trial equipment. We prepared to make some experiment between Mount Futago at Hakone near Fuji Mountain and the JRC Corporation in Mitaka; that was heard by the General Headquarters and the Electric Communication Laboratory at that time also knew about that experiment.

Aspray:

So the experiment hadn't occurred yet, but word about this had been learned by both the Electric Communication Laboratory and by the GHQ?

Nakajima:

At that time, transmitting electromagnetic waves had to be approved by the authorities. I went to the Electric Communication Laboratory to ask for the approval.

Aspray:

I see, so not only did they just happen to hear it, they had to have heard about it because they had to give their approval.

Nakajima:

The president of the Electric Communication Laboratory did not understand the usage of electrical wave for communication. He thought it was nonsense to use such an unstable propagation wave for communication equipment. But at that time one very important person named Frank Polkinghorn of GHQ visited the Electric Communication Laboratory and found that there were no experiments about microwaves. He was surprised.

Nakajima:

But at that time, the president answered. Of course, meanwhile we were ready to make the experiment, elsewhere.

Aspray:

I'm not sure I understand. So Polkinghorn says, "Aren't you doing any microwave research?" The president of the Electric Communication Lab says, "Oh, yes, we're going to do this and that, but we're not going to do it here." Is that it?

Nakajima:

Yes.

Takahashi:

JRC tried to establish a test from Mount Hakone to JRC. To get the approval, the Electric Communication Laboratory had denied JRC the use of radio. But the GHQ officer named Polkinghorn, a civil communications service officer, asked the director of the Electric Communication Laboratory, "Why aren't you promoting microwave study?" Therefore the director of the ECL commanded JRC to stick a new label over the label of JRC, "Electric Communication Laboratory," and just go test.

Aspray:

So that it looks like ECL's rather than JRC's.

Takahashi:

Right. Basically the company was correct, but was much indebted to Mr. Polkinghorn of GHQ.

Fish Detection Equipment

Nakajima:

This is now about fish finding. The history is that Navy men were using an ultrasonic submarine detection system and finding a strange phenomenon. It would identify a submarine but then the submarine would suddenly be gone, and they suspected that it would be a school of fishes. I heard the idea, and after the war I tried to use this idea to find a school of fish. I proposed this idea to GHQ to make an experiment. GHQ declined because this was related to weapons. But I insisted, "No, we can use even one sardine on the table, we are so short of fishes." I asked several times over two years, but GHQ declined very adamantly. I asked my elder brother, Dr. Ito, and he asked Dr. Kelly who saved the Japanese science and technology in post-war years. Ito insisted, so Kelly finally gave secret permission to me to do an experiment. When we did the experiment, we very clearly identified a school of fish. That experiment was successful. I really believe that Kelly was a sort of saint, that he saved Japanese science and technology. He was an intimate friend of my brother's, and there are words dedicated by Kelly when my brother died.

Aspray:

I see. This is Harry C. Kelly.

Nakajima:

Harry C. Kelly, yes. That experiment was successful, but fishermen were skeptical at first. They thought that with their long experience, they knew how to find fish. But the experiment was successful. They could get a lot of fish, so the fishermen were enthusiastic about this device. This now costs fifty thousand, but at that time about a million Yen.

Aspray:

I see.

Nakajima:

Demand was so great that we sold out of this device, so the fishermen had to wait. We exported it to the U.S. and many other countries.

Aspray:

I see.

Nakajima:

A newspaper company was very interested and asked to come on board to witness the experiment. Then the findings of the successful experiment were broadcasted nation-wide. The first cost was a million yen, but we changed it from nickel oscillator to an oxide compound. BaTiO3. This is manufactured by Murata, a Japanese company, and was a Japanese invention. Because of this innovation, the cost went from a million to fifty or sixty thousand.

Aspray:

Yes.

Nakajima:

After that I visited RCA and the Bendix Company, and showed the device. That surprised the engineers at Bendix because they were just borrowing that device from the Navy to develop their weapons. Probably the Navy also kept that device.

Aspray:

Can I go back and ask a question about the experiment on the communications channel? Did that succeed, and did it result in a technology that was implemented in the country?

Takahashi:

I think so. It was successful. It was the beginning of Japanese multiplex telecommunications by microwave.

Aspray:

But did it directly stem from this particular experiment, or did it come from some other direction?

Takahashi:

The main topic for him was the oscillation of the magnetron wave and the reception of the magnetron wave.

Aspray:

I see. So you were far from being at a communications system at this point; you were just showing proof of principles?

Takahashi:

To show a transmission line using PTM method.

Nakajima:

A certain doctor was interested in this fish-finding device and asked me to try to use this device to diagnose on the human body, the conditions of organs. I was at first very surprised but tried to develop a device. It was a very difficult process, and it took about twenty years. I was also asked to use this device for meteorological purposes. When did meteorological radar begin to be used in the United States?

Aspray:

I don't know. I'm sorry.

Takahashi:

All principal points have been covered. You know that this fish finding and diagnosis is the beginning of his present company, Aloka. Fish finding is one of the best sales of JRC, and it was a peaceful application. Communication was a peaceful application, the main peaceful application of radar technology. I think he contributed much not only to the military application, but also...

Aspray:

Also to these commercial ones.

Takahashi:

Yes, and I think that he is very proud of that, being one of the real original developers of the magnetron technology.

Aspray:

Very good. Well, thank you very much.

Nakajima:

Thank you very much.