Horology: time measuring systems or devices – Chronological – With supplemental power source
Patent
1998-10-05
2000-05-30
Miska, Vit
Horology: time measuring systems or devices
Chronological
With supplemental power source
368 66, 368204, G04B 100, G04B 900, G04C 300
Patent
active
060698462
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an electronic watch incorporating electric power generator for generating electric energy by utilizing externally available energy, and particularly, to an electronic watch having a function of storing the electric energy generated for use in driving the same.
BACKGROUND TECHNOLOGY
As conventional electronic watches, there are electronic watches provided with built-in electric power generator for converting external energy such as photovoltaic energy, mechanical energy, or the like into electric energy so that the electric energy can be utilized as driving energy for executing time display operation.
Among such electronic watches provided with the built-in electric power generator, there are included a solar cell watch using a solar cell, a mechanical electric power generation watch for utilizing electric energy converted from mechanical energy generated by rotation of a rotary weight, and a temperature difference electric power generation watch for generating electric power by utilizing the difference in temperature between the opposite ends of each of integrated thermocouples.
It is essential for these electronic watches provided with the built-in electric power generator to have built-in means for storing external energy therein while it is available so that the watch is driven continuously and stably all the time even after the external energy is gone.
For this reason, an electronic watch with a charging function, incorporating means for storing external energy therein, has been disclosed in, for example, Japanese Patent Laid-open Publication H 6-31725. An outline of circuits in the vicinity of a power supply source of the electronic watch is described with reference to FIG. 13.
An electric power generator 10, which is a solar cell, a first diode 11 and a capacitor 23 of small capacitance form a closed circuit, and further, a clocking block 24 for executing time display operation by use of electric energy and the capacitor 23 are connected in parallel. The electric power generator 10, a second diode 12, first switch 13, and secondary power source 31 form another closed circuit. A second switch 14 interconnects the positive source of the capacitor 23 and that of the secondary power source 31 in such a way as to connect the capacitor 23 and the secondary power source 31 in parallel.
Further, a first voltage comparator 16 controls the first switch 13 by comparing the terminal voltage of the capacitor 23 with a predetermined threshold value, and a second voltage comparator 17 controls the second switch 14 by comparing the terminal voltage of the secondary power source 31 with that of the capacitor 23.
In this electronic watch, as soon as electric energy is generated by the electric power generator 10, the capacitor 23 is immediately charged with electric energy, and the clocking block 24 is actuated by the electric energy stored in the capacitor 23.
When the terminal voltage of the capacitor 23 reaches a predetermined level or a level higher than that, the first switch 13 is closed by the agency of the first voltage comparator 16, and the secondary power source 31 is charged with the electric energy generated by the electric power generator 10.
When electric energy is not generated by the electric power generator 10, the terminal voltage of the capacitor 23 declines due to consumption of the electric energy by the clocking block 24, but when the terminal voltage of the secondary power source 31 is compared with that of the capacitor 23 by the second voltage comparator 17, and found to be higher than the latter, the second switch 14 is closed, thereby enabling continued operation of the clocking block 24 by the electric energy stored in the secondary power source 31.
The terminal voltage of the secondary power source 31, however, varies depending on the amount of electric energy stored, and with reference to a generated voltage of the electric power generator 10, there will arise a problem of the generated voltage undergoing changes depending on an extern
REFERENCES:
patent: 5835457 (1998-11-01), Makajima
patent: 5943301 (1999-08-01), Igarashi
Citizen Watch Co. Ltd.
Miska Vit
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