| 摘要 |
PURPOSE:To prevent the generation of an internal after image by applying a saturation type amplitude limit to a difference signal exceeding a prescribed threshold level and applying a general proportional operation having a linear area across a blind sector to the difference signal below the threshold level. CONSTITUTION:When the difference signal between an input video signal and a delay output video signal exceeds the prescribed threshold level, the saturation type amplitude limit by an amplitude limit circuit 14 and a coefficient circuit 17 is applied and when it is below the threshold level, the general proportion operation having the linear area across the blind sector by an adder-subtracter 16 is applied. Accordingly, when the difference signal exceeds the threshold level, as the difference signal grows larger, the coefficient is suppressed to shorten an after image time constant and when the difference signal goes below the threshold level, as the difference signal grows smaller, a response sensitivity to the step change of the input video signal is enlarged and a time for setting an output is shortened. Thereby, the generation of an unnecessary after image can be prevented.
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