| 摘要 |
PURPOSE:To control automatically whether a chrominance signal of the PAL system is switched to be supplied to a 1H delay line and an adding and subtracting circuit or not, by providing a switching circuit consisting of two transistors (TRs) in a chrominance processing circuit common to the NTSC system and the PAL system. CONSTITUTION:A switching circuit 63 controlled by the output of a discriminating circuit 62 of the video signal system is provided between an amplifier 10 of a common processing circuit for chrominance signals of color video signal of the PAL system and the NTSC system and a delay line 64 having a delay quantity of one horizontal period as well as an adding and subtracting circuit 65 to which the output the delay line 64 is supplied. The switching circuit 63 is provided with a TR Q2, which receives the chrominance signal from the amplifier 10 by the base and supplies the collector output to the delay line 64 and supplies the emitter output to the adding and subtracting circuit 65, and a TR Q1 which receives the chrominance signal from the amplifier 10 and the output of the circuit 52 by the base and has the emitter connected to the emitter of the TR Q2 and has the collector grounded, thus controlling automatically whether the chrominance signal of the PAL system from the amplifier 10 is switched to be supplied to the delay line 64 and the adding and subtracting circuit 65 or not. |
