Film projector with roller sound-head and sprocket gate drives - which are synchronized mechanically, uses infinitely variable ratio cone belt drive

摘要

The film F is drawn steadily through the sound head (30, 36) by flywheel (7)-stabilised rollers (9, pressure roller 13) belt-driven (6, 8) from the projector motor general drive (covering the intermittent motion through the film gate) is by chain (27)-driven sprockets (23, 24), the chain being driven (through gears (18, 21) by means of a belt and cone pulleys (14, 15). To keep the two drives synchronised, the length of film between the roller drive (9) and the lower sprocket (24) is continuously tested by a feeler (32) at the end of a spring loaded (33) lever (31, fulcrum 40)position of the feeler (32) are translated (via pin 34 and rod 35) into movements of the belt (16) across the cone pulleys (14, 15) and thus into a speeding-up or slowing-down of the sprocket (film-gate) drive as necessary to match the roller (sound-head) drive.