| 摘要 |
PURPOSE:To provide a circuit to produce a gate voltage in a gate insulated type bipolar transistor which performs light emission control of a flash device, wherein the rise of the gate voltage is quickened by allowing an element producing the gate voltage to carry out the switching motions. CONSTITUTION:The power is supplied to a control circuit and a booster circuit when a power switch is closed, and the boost control terminal of a control circuit emits a boost signal, which is fed via a resistance R2 to the base of a transistor Q2 to turn it on. Thereby another transistor Q1 is also turned on, and the booster circuit starts the boosting operation, as known according to the conventional technique. The boosting current charges a capacitor C3 through diodes D2, D3 and also charges another capacitor C2, wherein the charging voltage for the capacitor C3 is monitored through the capacitor C2 at a charge voltage sensing terminal RY and a boost stop voltage sensing terminal MON. When the voltage of the capacitor C3 exceeds the specified, first voltage value, a signal is emitted from a terminal RDY displaying the charging situation with the control circuit through the terminal RY and an LED is lighted. When the second voltage is reached. the boost signal is stopped through the terminal MON. |
