| 摘要 |
An electronic flash device includes a control circuit for extending the operational life of the flash battery. In one preferred embodiment the flash device is of the type having a monitor circuit responsive to the charge on the flashtube firing capacitor that (1) operably couples the flash battery to a charging circuit when the charge on the firing capacitor is below a predetermined level, and (2) de-couples the battery from the charging circuit when the firing capacitor charge is above the predetermined level. The control circuit comprises a counter for counting the number of times the monitor circuit couples the battery to the charging circuit and for producing a control signal, when the number counted reaches a pre-set value, that overrides the monitor circuit to maintain the battery de-coupled from the charging circuit. In a second preferred embodiment the flash device comprises a time-delay control circuit that de-couples the flash battery from the charging circuit a predetermined interval after the firing capacitor is initially charged to a level adequate to flash the flashtube. |
