Film transport counter for camera - uses detector elements on back pressure plate and camera body to detect perforations and count by logic circuitry

摘要

Appts. and associated circuitry measure the length of film transport in a camera. Detector elements count the film perforations by responding to changes in electrical capacity. Detectroelements (10, 11) are mounted either side of the film (17) at the top and bottom of the pressure plate, and correspondingly in the camera body on the other side of the film. The logic circuitry used for counting is triggered by the changes in capacity as film and perforations pass between the detector elements.