| 摘要 |
<p>To compensate for the effects of film instability in a film gate, a film instability compensation system comprises a positional transducer (2) for measuring the position of the film edge relative to a sprocket hole (4) which is maintained in contact with a sprocket tooth (6) by pressure roller (8). Positional tranducer (2) measures the distance between the film edge and a sprocket hole and then measures deviations from the distance for subsequent sprocket holes to form a compensation signal. The output of the positional transducer (2) is coupled to a delay unit (10) 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 incurred due to the relative lateral displacement of the sprocket holes, are stored in the memory 30 and are applied to a subtractor circuit 24, within which the compensation signal from the output of the pipeline register 22 is adjusted to take account of the 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. <IMAGE> <IMAGE></p> |
