| 摘要 |
PURPOSE:To operate the electric timepiece immediately even when a secondary power source is ''0''V by providing an overcharge preventing means for setting a power source system in a chargeable state and a driving means for the electronic timepiece. CONSTITUTION:A voltage divided by resistances 203 and 204 varies in proportion to the voltage of the secondary power source 210 and is applied to one input of a comparator 206. Then, a constant voltage is outputted to the other input of the comparator 206 from a reference voltage generating circuit 205 without any influence of voltage variation of the secondary power source. Those two inputs are compared with each other; when the resistance-divided voltage becomes higher than the reference voltage, the comparator 206 outputs a low potential to short a transistor 207 (TR). When the secondary source voltage drops below the voltage of the comparator 206 and circuit 205, the voltage of the TR207 becomes unfixed, so it is pulled up by a resistance 202 to prevent the TR207 from turning on. |
