Rank Cintel Limited

Richard T Such

Terence W Mead

A film instability compensating system compensates for the effects of film instability in a film gate. The film instability compensation system includes a positional transducer for measuring the position of the film edge relative to a sprocket hole which is maintained in contact with a sprocket tooth by a pressure roller. The positional transducer measures the distance between the film edge and a sprocket hole and then measures deviations from the distance for subsequent sprocket holes to determine a compensation signal. The output of the positional transducer is coupled to a delay unit which delays the signal corresponding to the error at a particular sprocket hole until that sprocket hole reaches the film gate. Signals representative of the cyclic errors caused by the relative lateral displacement of the sprocket holes, are stored in a memory and are applied to a subtractor circuit. In the subtractor circuit, the compensation signal from the output of a pipeline register delay is adjusted to compensate for cyclic errors, and to provide an overall compensation signal which is applied to the horizontal scan shift when the appropriate sprocket hole reaches the film gate.

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Bishops Stortford, United Kingdom

Richard T Such