| 摘要 |
PURPOSE:To make it possible to turn on and off the blanking processing in a video and a chrominance signal processing circuit by switching only the level of a fly-back pulse by a pulse level switching circuit. CONSTITUTION:A comparator 13 compares reference voltage VS1 with a fly-back level and a comparator 14 compares a reference voltage VS1+VS2 with a fly- back pulse level. When the fly-back level is larger than the reference voltage, each comparator generates an output pulse. The output of the comparator 13 is sent to an AND circuit 15 which is ANDed by a horizontal synchronizing pulse and the fly-back pulse to output the AND through a waveform shaping circuit 16 as a gate pulse. On the other hand, the output of the comparator 14 is inputted to a waveform shaping circuit 17 and its output pulse is inputted to a blanking processing circuit 18 as a blanking pulse. |
