Patent for Timepiece with thermoelectric generator

[rewolf]

I stumbled across this patent:
http://www.patentstorm.us/patents/6359841-fulltext.html
At first glance it describes the Bulova Thermatron, but it was issued on March 19, 2002 - many years after the Thermatron.
The assignee is Seiko, AFAIK they also had a thermoelectric watch, but later than Bulova.
Can someone more familiar with "Japanese Patent English" tell what makes it different from the Thermatron?

Edit: even more patents with very subtle differences....
http://www.patentstorm.us/patents/search-results.html?search=Thermoelectric+timepiece
http://www.patentstorm.us/patents/6304520-fulltext.html
http://www.patentstorm.us/patents/5889735-fulltext.html

However I still don't get the point of the first one mentioned above.

[azimuth_pl]

to me it appears to describe the Thermatron in detail - perhaps there are some small differences that are not described in detail.
btw. do you know of any ways of waking up a NOS Thermatron, not to mention to open the back that has very fancy screws? I know that 99% of these do not work but there is always a chance

[rewolf]

...btw. do you know of any ways of waking up a NOS Thermatron, not to mention to open the back that has very fancy screws? I know that 99% of these do not work but there is always a chance

I'm afraid I never had a Thermatron in my hands - though I'm always tempted to bid on one of those offered on ebay.

The problem is the battery, a Leclanche 4106 with 1.1V. Often it has gone bad and killed the movement.
If not, it is probably possible to replace the battery and get a working Thermatron - this thread has information about rechargeable watch batteries. The low voltage batteries might work.

There was also a design flaw - if the battery ran empty, the watch would never start again. I suppose this is because the thermogenerator delivers only 175mV: this is not enough to drive any semiconductor circuit, so the the circuit that steps up the low thermogenerator voltage to the required 1.4V would not start.
It is common practice with step-up circuits designed for low input voltages to supply the step-up circuit with its own output voltage (this is called bootstrapping) - as long as it runs, it can step-up input voltages as low as 0.1V, but if it ever stops, it needs at least 0.6V to start again.


A company named STW modified a couple of Thermatrons, a few appeared on ebay years ago.
They replaced the flat back plate with a bulged version that gave room for an 0.47F capacitor. There was a big screw in the middle of the back plate to access the capacitor contacts and "jump-start" it with an external battery to get the curcuit going. With the capacitor the watch has only 48h power reserve as opposed to 3-4 months with a (working) battery.

Information (German) and images of Bulova Thermatron, and STW Thermatron

The Thermatron in Doensen's book

An Italian site with apparently interesting information, but I never learnt Italian, so here's the Babelfish translation

French posting with some very nice closeup pictures.

Just googled a bit, found a site with an STW Thermatron for sale:
http://www.retro-watches.co.uk/Bulova-Thermatron-Ref-JUN0757.htm

[azimuth_pl]

thanks for the vast amount of information in one place.
I have the original piece thus I'm curious if I could try to kickstart the movement somehow? or will it always require the capacitor like the STW?
however I need to open the back somehow - it has a very small, fancy and handsome bolt/nut like screw that can not be unscrewed without the proper screwdriver.

[compaid]

Hex driver for thermatron. Impossible to source, however you can make one for a few euros. Buy a quality artist brush with a small 1mm end. Buy the hard brass type not aluminium or foldered type. Buy a 1.5mm alan key and drive throught the metal (after removing the wood of course, and brush. If a bit of the end comes off dont worry. Once it appears, file with alan key inserted to produce a nice square end. Then keeping the alan key inserted, gently press the tube using the pliers to press a bit more of the tube to the hex.

You will find its a tight fit but works ok. Nuts are not that tight. You can replace the battery with a recharable V6HR and file down a small nut to act as a spacer, cut a biro tube (soft plastic type to make a sleave.

If all ok the watch will start on the battery or after a bit of heat on the bottom of watch.