(Nikkei BP Group)
(No.1 High-Tech News Site in Japanese)
| Seiko to Sell Wristwatch Powered by Body Temperature
November 30, 1998 (TOKYO) -- Seiko Corp. and Seiko Instruments Inc. developed
a wristwatch driven by a generator powered by body temperature and priced
at about 300,000 yen (US$2,470).
|The generator is a "Seebeck element" device. Its heat source is the temperature
difference between a person's arm and the ambient air. The watch will
be marketed from Dec. 15.
The Seebeck element is made of BiTe, and it has a thermoelectromotive
force of 0.2 mV/deg C, company officials said. Its shape is a column
of 80 x 80 x 600 micron. The two companies fabricated a module by sandwiching
100 elements between silicon substrates and connected 10 modules in
The output voltage is 0.15 V and a Ti-Li-ion secondary battery with a
power of 4.5 mAH is charged through a transformer.
When the watch is removed from a person's arm and is not powered, its
second hand indicates the remaining battery power, while the minute
and hour hands continue working.
If the watch is not worn for three days, the minute and hour hands stop.
However, the watch's internal circuits continue operating and the watch
starts immediately when it is worn again. The hands are automatically
set at the correct time.
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