Synchroniser for sound cine projector - compares pulses from projector with reference speed from tape by counter delivering film speed control signal

摘要

Synchroniser compares the number of pulses corresponding to film speed of a cine projector with the number of pulses corresponding to a reference speed from a sound tape reproduction system, by means of a counter. The latter produces an output signal for controlling film speed of the cine projector. Between the drive source of the projector and a film conveyor is a speed adjuster for the film conveyor. A film transport control drive for controlling the speed adjuster responds to the output signal of the counter. The system allows equalisation of phase defects which occur when the projector itself is two or more frames away from precise synchronisation between picture and sound.