| 摘要 |
PURPOSE:To rationally and effectively use the charging energy from a solar cell according to circumstances, by a method wherein a bidirectional current control circuit is turned ON when the voltage of the large capacity power source among power sources respectively charged by solar cells reaches a predetermined value or more. CONSTITUTION:When there are no residual charges in the first and second condensers 4, 7 of small and large capacity power sources respectively charged by first and second solar cells 6, 7 and a time-piece is placed under a low illumination state, the condenser 4 is rapidly charged with the driving voltage of a time-piece driving circuit 3 and clock function works. When the charging voltage of the condenser 7 reaches the driving voltage of the circuit 3, the transistor 31a of a bidirectional current control circuit 31 is turned ON through a voltage detection circuit 30 detecting this state and the condenser 7 is quickly charged from both of the cells 8, 6 to be prepared for the driving succession of the circuit 3 at the time of the lowering in the voltage of the condenser 4 when luminous intensity comes to 0. By this method, the charging energies from the solar cells are used rationally and effectively according to circumstances and, even at the time of the lowering in the voltages of both cells, clock driving is rapidly performed by re-irradiation.
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