| 摘要 |
PURPOSE:To reduce a flicker of display by individually detecting levels of an input video signal and an input video signal having passed through a delay line, by controlling the levels of the input video signals to an equal value in accordance with the detected levels, and then by changing them over. CONSTITUTION:The sink chip level of the output of demodulator 5 and fixed reference voltage Ec and compared to each other by comparator 14, the output of which is supplied to and held by capacitors 16 and 17 by way of change-over switch circuit 15. This held voltage is supplied as a detection signal to frequency threefold multiplier 1 by way of change-over switch circuit 18 and in accordance with the level detection signal, the amplitude of the output carrier of miltiplier 1 is controlled. Through circuits 15 and 18, each level-detection signal of a video signal having passed through delay line 3 and that not having passed are held by capacitors 16 and 17 and switch circuit 8 and circuits 15 and 18 supplying each level-detection signal to multiplier 1 separately are put into operation coupling with one another to equalize amplitude levels of the video signals, thereby reducing a flicker of switching display. |
