| 摘要 |
PURPOSE:To keep the hue of a receiver constant even if the contrast and a color- saturating variable resistance are varied, and also to reduce the number of control signal input terminals to one by adding two demodulated color difference signals, by making the addition ratio variable and then by sending the sum to a hue control circuit. CONSTITUTION:Composite video signal A, extracted through a video detecting circuit which is not shown in the figure, is input to composite video block 1, where it is demodulated through color signal processing circuit 2 to output color difference signals R-Y, B-Y and G-Y. Signals R-Y and B-Y are added together by way of resistances 15 and 5 reapectively and in thid case, the addition ratio of signals R-Y and B-Y is aadjusted by hue fine-adjusting variable resistance 6, so that the sum signal will be sent to hue control circuit 8. Consequently, even when contrast- adjusting variable resistance 10 and color-saturation adjusting variable resistance 11 and varied, the need for a control input signal to circuit 8 is eliminated, the hue of the receiver is held constant and the number of control signal input terminals can be reduced to one. |
