| 摘要 |
PURPOSE:To obtain a synchronizing signal generation circuit with excellent noise resistance by generating different patterns in accordance with a horizontal synchronizing signal and a vertical synchronizing signal and preparing horizontal and vertical synchronizing signals in accordance with the patterns. CONSTITUTION:A composite synchronizing signal 11 separated from a synthetic image signal is supplied to a pattern matching circuit 12, and whether it is a horizontal synchronizing signal or a vertical one is decided. When the circuit 12 decides a vertical synchronizing signal, the circuit 12 generates a vertical pattern detection pulse 14, which is supplied to a vertical synchronizing signal preparation circuit 17 through a vertical time gate circuit 15. In accordance with the pulse, a vertical synchronizing signal 20 is prepared and outputted. When the circuit 12 decides a horizontal synchronizing signal 27, the circuit 12 generates a horizontal pattern detection pulse 21 in the same manner, and the pulse 21 is supplied to a horizontal synchronizing signal preparation circuit 24, thereby preparing the horizontal synchronizing signal 27.
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