| 摘要 |
PURPOSE:To obtain a chrominance signal processing circuit capable of a stable APC action by inserting a psuedo burst signal being a reference for a equalizing pulse insertion period of a color signal and comparing phases always by means of an automatic phase control (APC) circuit. CONSTITUTION:An output of a reference liquid crystal oscillator 9 is added to a switch circuit 10, where the output is gated for only a burst gate pulse period in a 9H period for including an equalizing pulse, and added to a mixer circuit 20 through an amplifier 12. In said mixer circuit 20, a signal of said gated reference oscillator 9 is mixed with a burst signal which is sampled by a reproduction color signal obtained on a terminal 18, and the mixed signal is added to a phase comparator 21. Said comparator 21 compares a phase of this signal with that of the reference oscillator 9, and controls frequency of a voltage control liquid crystal oscillator 13. Thus even in an equalizing pulse period, the phase comparison by an APC circuit can be executed, and color turbulence can be almost eliminated.
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