| 摘要 |
PURPOSE:To prevent the occurrence of the disturbance of synchronization with respect to a reproduced video signal by selecting a reproduced horizontal synchronizing signal as an input signal being an object of synchronization in the vertical blanking period of the reproduced video signal, just after track jump or in a period when no color burst signal exists in the reproduced video signal. CONSTITUTION:A selector 26 is returned to the position (a) and an object of lock is switched to the reproduced horizontal synchronizing signal for a vertical blanking period, just after track jump, search period or a period where no color burst signal is inputted. Moreover, when the color burst is locked, a selection 24 is switched to the position (b) to select an output of an adder 23. In this case, a control circuit 20 calculates a phase difference of outputs of a phase comparator 27 and an output of a phase comparator 22 and averages the result and gives it to other input of the adder 23. Thus, the output of the adder 23 reaches a value nearly equal to the phase to phase error of the color burst signal. Thus, the synchronization is not disturbed by the reproduced video signal. |
