| 摘要 |
PURPOSE:To compensate the absence of a synchronizing signal even if the synchronizing signal is absent and to prevent servocontrol from hunting by supplying a count output which is generated in a horizontal scanning period after a counter is reset and a playback horizontal synchronizing signal to the reset input of the counter. CONSTITUTION:A playback composite synchronizing signal PBCS is separated from a playback video signal from a disk and a rise detecting circuit 1 extracts its leading edge. The extracted pulses pass through a mask gate G1 and are further supplied to the clear input CL of the counter 2 from a gate G3 to reset the counter 2. The counter 2 counts clock pulses CK of sufficiently high frequency with the time width of one horizontal scanning period and generates a timing output for reforming a synchronizing signal. The A output and B output of the counter 2 are supplied to the reset input S and reset input R of an FF 3, which outputs a re-formed horizontal synchronizing signal DLPH. Thus, even if the synchronizing signal is absent, that is compensated to prevent the servocontrol from hunting.
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