| 摘要 |
PURPOSE:To improve the chrominance reproducibility of a video by operating a clamp circuit when a prescribed time elapses from the switching time of respective horizontal scannings within a blanking period. CONSTITUTION:The clamping circuits 19, 20 are disposed between the respective output terminals of gain control circuits 7, 8 and the input terminal of a demultiplexer 9, the clamp circuit 21 is disposed between the output terminal of the demultiplexer 9 and a process circuit 10 and these clamp circuits 19-21 are controlled by a control signal CP generated from a control signal generating circuit 22. The control signal generating circuit 22, when line select signals LS are alternately inverted within the blanking period BK, the control signal CP is generated when a constant delay time Td elapses. Thereby, the clamp circuit 19-21 start of operate in the horizontal scanning period (1H) to prevent the deterioration in the chrominance reproducibility.
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