Horology: time measuring systems or devices – Chronological – With power monitor
Patent
1998-03-31
2000-05-09
Roskoski, Bernard
Horology: time measuring systems or devices
Chronological
With power monitor
368204, 368 64, G04B 100
Patent
active
060613041
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an electronic watch incorporating electric power generator by utilizing externally available energy, and storing the electric energy generated by the electric power generator, that is driven by the electric energy.
BACKGROUND TECHNOLOGY
There are electronic watches provided with a built-in electric power generator for displaying time by converting external energy such as photovoltaic energy, thermal energy, mechanical energy, and the like into electric energy (generation of power), and by driving a watch driving system with the use of the electric energy.
Among such electronic watches with the built-in electric power generator, there is a solar cell power generation watch for converting photovoltaic energy into electric energy by use of a solar cell, a mechanical energy conversion power generation watch for converting mechanical energy of the rotation of a rotary weight into electric energy, a temperature difference power generation watch for generating power by utilizing the difference in temperature between the opposite ends of each of integrated thermocouples, and the like.
It is essential for these electronic watches provided with the built-in electric power generator to be driven stably and continuously even in case the supply of external energy is cut off. Accordingly, these electronic watches are also provided with electric power storage means therein such as a secondary cell, a large capacity capacitor, or the like to store electric energy generated by the electric power generator when external energy is available so that the watches can be continuously driven by the electric energy stored in the electric power storage means when the electric power generator is unable to generate power.
This type of electronic watch with a built-in electric power generator has been disclosed in, for example, Japanese Patent Laid-open publication H 4-81754. FIG. 9 is a block diagram showing the general arrangement of the conventional electronic watch with the built-in electric power generator.
In the electronic watch shown in FIG. 9, a small capacitor 132 is connected in series with the electric power generator 130 by external energy, such as a solar cell or the like, via a diode 138 which is first reverse flow preventing means, and clock means 131 and a controller 140 are connected in parallel with the small capacitor 132. Further, a large capacitor 133 is connected in series with the electric power generator 130 via a charge switch 134 and a diode 139 which is second reverse flow preventing means.
A discharge switch 135 is interposed between the small capacitor 132 and the large capacitor 133. Further, first voltage detector 136 and second voltage detector 137 are connected to the small capacitor 132 and the large capacitor 133, respectively, so as to be able to detect terminal voltages of the respective capacitors.
In the electronic watch with the built-in electric power generator when the electric power generator 130 generates sufficient electric power, the clock means 131 is driven by the electric energy supplied thereby while the small capacitor 132 and the large capacitor 133 are charged also by the electric energy. However, when the electric power generator 130 is unable to generate electric power, the clock means 131 is driven continuously by electric energy stored in the capacitors.
When the amount of electric energy stored in the large capacitor 133 is small and the terminal voltage thereof is at a low level and the electric power generator is not generating electric power, the clock means 131 is deactivated owing to the small little amount of electric energy stored in the small capacitor 132, then the charge switch 134 and the discharge switch 135 are open.
When the electronic watch is in this state and the electric power generator 130 starts generation of electric power, electric energy generated is thereby accumulated only in the small capacitor 132, and consequently, the terminal voltage of the small capacitor 132 rises relatively quickly, enabling
REFERENCES:
patent: 4099372 (1978-07-01), Beyers, Jr.
patent: 4182110 (1980-01-01), Kamiwaki et al.
patent: 4395135 (1983-07-01), Frantz
patent: 4634953 (1987-01-01), Shoji et al.
patent: 4702613 (1987-10-01), Ohtawa
Hiraishi Hisato
Nagata Yoichi
Citizen Watch Co. Ltd.
Roskoski Bernard
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