| 摘要 |
A control circuit for flash tube apparatus has a flash tube, a thyristor for controlling the flash tube in ON-OFF fashion, a trigger circuit for triggering the flash tube and thyristor, a commutation capacitor for turning the thyristor OFF, a switch circuit for supplying a charge stored in the commutation capacitor to the cathode-to-anode path of the thyristor. The control circuit further includes a trigger blocking circuit connected between the trigger circuit and the gate of the thyristor, a carrier recombination capacitor connected in parallel with and across the gate and cathode of the thyristor, and a timer circuit for operating the trigger blocking circuit for a predetermined time period. The thyristor is turned ON by a trigger pulse TP2 from the trigger circuit. When the switch circuit is rendered ON, the timer circuit is operated. The trigger blocking circuit blocks the trigger pulse until the discharge of the commutation capacitor is completed. The thyristor is reverse biased by the commutation capacitor and shifted to the turn-off state. The carrier recombination capacitor is charged by part of a current from the commutation capacitor. A charge stored in the carrier recombination capacitor recombines a residual carrier of the gate region of the thyristor. |
