Electronic flash apparatus

Claim 1

Electronic flash apparatus comprising a storage capacitor, a flash tube and a thyristor in series with each other and in parallel with said storage capacitor, ignition means for igniting said flash tube so that current from said storage capacitor may flow through said tube to create a flash of photographic light therein, and extinction means for stopping flow of current through said tube to stop emission of light therefrom when sufficient light for the photographic purpose has been produced, said extinction means including an impedance located in the discharge circuit between said storage capacitor and said tube, said impedance having an intermediate tap, a commutating capacitor and an electronic switch connected in series with each other and in parallel with said tube and thyristor through said intermediate tap, a by-pass resistor in parallel with said commutating capacitor and a portion of said impedance, a third capacitor and a potentiometer circuit in series with each other and in parallel with said thyristor, the gate of said thyristor being connected to an intermediate point of said potentiometer circuit, and a circuit connection from a junction between said third capacitor and said potentiometer circuit to a junction between said commutation capacitor and said electronic switch, said circuit connection including diode means and a fourth capacitor in series with each other.