Electronic photographic flash unit

Details Electronic photographic flash unit Electronic photographic flash unit

1975-04-01

1976-12-21

Hayes, Monroe H.

Optics: motion pictures

Projection light sources

Intermittent light

354 33, 354145, 315241P, G03B 2100

Patent

active

039985342

ABSTRACT:
An electronic flash unit for photographic purposes, in which there is a first thyristor in series with the flash tube, and a second thyristor which, in series with a quenching capacitor, is in parallel with the first thyristor. The first thyristor is quenched at the appropriate time, by quenching current from the quenching capacitor, and after the first thyristor has been rendered non-conductive, the second capacitor is also rendered non-conductive by forced commutation. The arrangement shortens the recovery time of the apparatus, as compared with prior art apparatus of this same general type, to such an extent that the flash apparatus may be used with a motion picture camera as well as a still camera, to produce one or more flashes during each shutter-open cycle of the motion picture camera. In a further development of the invention, a circuit is provided for producing three separate flashes during each opening of the shutter of a motion picture camera, thereby overcoming the stroboscopic effect which might be unpleasantly noticeable to a person being photographed, and producing flashes with such rapidity that to a person being photographed they will appear as a single continuous flash.

REFERENCES:
patent: 3710701 (1973-01-01), Takashima
patent: 3779142 (1973-12-01), Yata

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