Film projector gate and shutter - with shutter blade operating pulse synchronisation circuitry controlling film advance stepping motor

摘要

Transport and shutter mechanism for a film projector is such that the film advance is controlled by electrical impulses from the shutter mechanism. The shutter blades (13) are continuously driven by an electric motor (7). Extensions on the shutter (21) interrupt a light path from a light source (15) to a photocell (16) and provide a pulsed signal to the control circuitry (17, 18, 19) for the step motor (4) driving the film (2) past the projection aperture (3). Pulses cause the stepping film advance motor (4) to advance the film one frame by using a direct drive toothed wheel (6). The control circuitry (17, 18, 19) uses gate circuits and JK bistables.