Frame counter initialization sensor for triggering film rewind when camera door opened prematurely

摘要

A photographic camera has a motorized film transport mechanism which is operable to continuously prewind substantially the entire length of a filmstrip from a light-tight cartridge onto a take-up spool without exposing any of the frames on the filmstrip and to intermittently rewind the filmstrip one frame at a time back into the cartridge after each exposure is completed. A frame counter is incremented during prewinding of the filmstrip onto the take-up spool to provide a count of the maximum number of frames to be exposed and is decremented during rewinding of the filmstrip back into the cartridge to provide a count of the remaining number of frames to be exposed. If a rear door of the camera is accidentally or inadvertently opened before the filmstrip is completely wound off the take-up spool, the frame counter is initialized to an original setting. Then, a counter initialization sensor and a film-on-spool sensor cooperate with a control circuit to operate the motorized film transport mechanism to continuously rewind the filmstrip remaining on the take-up spool back into the cartridge.