Failsafe interlock for automatic exposure camera - with time delay to close shutter if not closed by exposure circuit to avoid subsequent faulty photographs

摘要

The automatic camera, with integral flash, operates the flash automatically as a fill-in mode if the illumination is not sufficient. The ready state of the flash contacts starts a failsafe time circuit which provides a shutter closing signal after a time interval corresponding to the longest flash exposure. The timing circuit comprises simple RC loops coupled to the exposure control. It is only operated when the fill-in flash is used. It prevents the shutter being left open with incomplete exposure, so that subsequent shots are not ruined.