| 摘要 |
PURPOSE:To obtain a regular AGC voltage and to prevent an AGC lockout by stopping an action of a noise removing circuit even when the noise larger than the amplitude of a synchronizing component is included in a video signal during the synchronization. CONSTITUTION:When the noise larger than the amplitude of a synchronizing signal occurs, an AGC noise removing circuit 2 is operated so as to stop an action of an AGC detecting circuit 1. An AGC detecting output 3 is smoothed through an inverting circuit 4 by the first AGC filter 6 and the second AGC filter 8. When a horizontal pulse 10 is detected by an AGC malfunction preventing circuit 11, and at the time of a horizontal pulse period, the AGC malfunction preventing circuit 11 stops the action of the AGC noise removing circuit.
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