Automatic control device for an electronic flash apparatus

摘要

A device for automatic control of the quantity of light from an electronic flash tube including a silicon controlled rectifier connected in series with the flash tube, a circuit for applying a reverse voltage between the main electrodes of said silicon controlled rectifier so as to open said rectifier, and a switching element connected between said reverse voltage applying circuit and said silicon controlled rectifier. Responsive to the output signal from the reverse voltage applying circuit, the switching element short-circuits the gate electrode and cathode of the rectifier. With this arrangement, it is possible to decrease the capacity of a commutation capacitor constituting part of the reverse voltage applying circuit.