| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of bend in an output TV picture by not affecting a dual AFC circuit at the time of separating a composite synchronizing signal to which a copy guard signal is added. SOLUTION: This vertical synchronizing signal separation circuit is provided with a current source 1, a current source 3 which supplies a current larger than that of the current source 1, a capacitor C1 for integration of the difference of the current values between current sources 1 and 3, and a comparator 12 for comparison between the voltage Vc of the capacitor C1 and a second reference voltage V2 and generates and outputs a vertical output pulse PV in the case that the voltage Vc of the capacitor C1 exceeds the second reference voltage V2. In this case, a current source 2 which supplies a current smaller than that of the current source 1, a switch SW1 which performs switching between the outputs of the current sources 1 and 2 to output the output of the current source 1 or 2 to the collector side of a transistor TR2, and a switch control part 31 which switches the switch SW1 to the side of the current source 2 in the period from the reset of vertical synchronization to the termination of the vertical blanking period are provided.
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