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US 4,379,312 AGranted
Control system for audio-visual projector
AssigneeIndal Limited
InventorMichael G. Lee
Life of this patent
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AssigneeIndal Limited
InventorMichael G. Lee
Estimating the term…
A system for the control and synchronization of magnetic tape and filmstrip in an audio-visual projector. Film is advanced by means of recorded advance tones on the magnetic tape which are detected by a tone detector to generate an advance pulse. An advance counter is incremented responsive to each advance pulse and decremented as the film advances each frame. The output of the advance counter actuates a film-advance mechanism unless the contents of the counter are zero, so that synchronization is maintained even if the rate at which the advance pulses occur exceeds the operating speed of the film-advance mechanism. Means are provided to automatically synchronize the tape and film at predetermined locations by optically sensing markers affixed to the tape and film. The system may also advance the tape independently of the film in either a fast-forward or a regular-speed mode or it may advance the film independently of the tape.
A control system for an audio-visual device for sequentially projecting a plurality of frames of a filmstrip and for presenting an audio program recorded on an audio tape including spaced-apart coded signals located at the start of each portion of each audio program associated with a frame of said filmstrip, said control system comprising:
Dependencies are inferred from the claim text.