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In keeping with Ibuka's ideal of "having youngsters come in contact
with science as early as possible," Sony today still takes an active part
in science-related exhibitions aimed at children. These activities have
gained Sony much public acclaim. One such event was the "Children's
Electronics Exhibit" held at the main branch of the Mitsukoshi Department
Store in Nihombashi, Tokyo.
Mitsukoshi's PR manager Shigeru Okada offered Sony free use of the
main store's large exhibit and roof areas for one week. Okada suggested
that Sony display some of its unique technology that would be of interest
to children, as the exhibition period coincided with the holiday week which
included Children's Day.
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 | The children's electronics exhibition at
the Mitsukoshi Department
Store in
Nihombashi, Tokyo. |
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After much consideration, it was decided to display a transistor and
a transistor radio production line complete with fifteen female workers who
peered into microscopes and assembled parts. These assembly lines, along
with a solar-powered helicopter and airplane, Japan's first VTR, and a
fully automated driverless car, were big hits among children and adults as
well.
The exhibit was a great success, easily topping 1.2 million visitors
over the week-long period, making it the largest drawing card in
Mitsukoshi's history. In fact, the crowds were so large that ropes had to
be drawn along all the staircases to control the long waiting lines. The
temperature in the hall was 3 higher than the rest of the building.
By that time, many Japanese companies had begun to produce
transistors. Their manufacturing processes were carefully guarded secrets,
however, and the very idea of putting them on public display was
unthinkable. Only Sony had the courage and resolve to expose its technology
to public view.
Then in June, Sony announced the successful testing of the Esaki
Diode, also known as the tunnel diode, which Sony researcher Leona Esaki
invented.
Two years earlier, Iwama, then manager of the Semiconductor
Department, had been trying to improve the poor yield percentage of the new
2T7 grown junction transistor. Tetsuo Tsukamoto of the Semiconductor
Department had developed it to replace the earlier 2T5 model.
During the six months he was bedridden while recovering from the side
effects of penicillin, Tsukamoto had constantly considered replacements for
the 2T5, which had a poor production yield and performance. High frequency
transistors require the creation of a thin base layer with a large amount
of impurities. An emitter layer, also with many impurities, has to be
deposited on top of that. The higher the effective impurity concentration
in the emitter, the greater the transistor's amplification. The problem was
determining the upper limit of impurity concentration. Tsukamoto hit upon
the idea of using phosphorous instead of the conventional antimony as the
impurity in the emitter. Immediately after his recovery, Tsukamoto
conducted experiments to corroborate his theory. The results were
unprecedented, and frequency characteristics five times higher than those
of the 2T5 model were obtained. Beyond certain levels, antimony impedes the
formation of germanium monocrystals and thus cannot be used in large
amounts. Phosphorous, on the other hand, can be mixed with germanium in
unlimited volumes, and the higher the concentration, the better the
crystals. And because phosphorous does not diffuse as much as antimony in
germanium, the thickness of the base can easily be made to design
specifications.
Iwama was overjoyed with the new transistor, called the 2T7. As noted
in the guinea pig article, the transistor field was no longer Sony's
unchallenged domain. In fact, the transistor makers were already involved
in a fierce price war. Sony felt that since its products were more
expensive, it would have to win out with new products and was forced to
expand into shortwave and FM radio. Thanks to the 2T7, however, it appeared
as though the problem of developing a high frequency transistor for use in
these new products had been resolved in a single stroke.
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