| 摘要 |
PURPOSE:To eliminate each noise pulse in a luminance signal and a chroma signal and to make the picture of a color TV receiver clear, by detecting a composite video signal at the pre-stage of a delay circuit and controlling the gain of a video amplifier and a band amplifier in good timing at the generation of noise. CONSTITUTION:An intermediate frequency signal S1 is detected at a video detection circuit 10 to pick up a composite video signal S2 consisting of luminance signal, synchronizing signal and carrier chrominance signal. This signal S2 is applied to a video amplifier circuit 20 and a composite video signal S24 amplified with the luminance signal in the signal S2 is outputted from the circuit 20. A chrominance carrier signal 42 is outputted from the 2nd band amplifier circuit 42. If any noise is present in the signal S2 branched at the pre-stage of the circuit 20, the leading edge of noise is detected at a differentiation circuit 80, a differentiation output signal S80 turns on a transistor TR1 of a switching circuit 90 to decrease the gain of the 2nd video amplifier circuit 24 and the 2nd band amplifier circuit 42 correspondingly, and each noise pulse can be rejected from the luminance signal and the chrominance carrier signal 42 in the signal 42 without giving effect on the picture. |
