| 摘要 |
PURPOSE:To reduce the capacity of a capacitor for light emission of a flash light emitting device and to reduce the titled device in size and energy to be consumed by connecting a diode and a thyristor for stopping light emission in parallel to an inductance element. CONSTITUTION:A main thyristor 7 is supplied with a gate current to turn off and a main capacitor 3 is discharged through a xenon discharge tube 16, the main thyristor 17, and a coil 14 for commutation to supply a main discharging current to the xenon discharge tube 16; while the discharge tube 16 emits light, the light emission quantity control circuit in a black II operates and a current proportional to reflected light is received from a photodetecting element 27, so that when the current reaches the preset quantity of the current of the photodetecting element, a proper light quantity signal is supplied as the gate current of a subordinate thyristor 23 through a resistance 26. Consequently, the subordinate thyristor 23 turns off and a reverse bias is applied between the gate and cathode of the main thyristor 17, which turns off. |
