| 摘要 |
PURPOSE:To relieve the effect onto a television screen by discriminating a vertical synchronizing signal and a horizontal synchronizing signal digitally at a point or a range where the signals are not susceptible to the effect of the horizontal synchronizing pulse in a composite synchronizing signal, an equivalent pulse and a notched pulse. CONSTITUTION:A setting value T1 of a setting device 51 is a value set to skip the horizontal synchronizing pulse from the trailing edge of the composite synchronizing signal within a half, and a setting value T2 of a setting device 61 is a value set within one period of the horizontal synchronizing signal after the elapse of time T1. Then the composite synchronizing signal is fed to a CLK terminal of a D-FF71 via an inverter 73 to apply the H level signal to the CLR terminal of a counter 52 from the terminal Q. The range where the signal level at a point of the time T1 from the first trailing edge of the composite synchronizing signal is at a low level is discriminated to be the portion of the vertical synchronizing signal and the trailing edge of the composite synchronizing signal extracted between the time T2 and the succeeding time T1 is discriminated to be the portion of the horizontal synchronizing signal. Thus, even if high frequency noise is superimposed, no effect is imposed upon the discrimination of the synchronizing signal.
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