| 摘要 |
PURPOSE:To effectively use the overall width of a V sync (vertical synchronizing signal) for the clamp operation by generating a clamp pulse in accordance with the width of the sync tip separated from a digital video signal by a comparator. CONSTITUTION:An input video signal and a reference value signal are compared with each other by a comparator 21 to separate and take out an H sync and a V sync. The output signal of the comparator 21 is inputted to a latch circuit 22 and is delayed by a prescribed extent (t) and is inputted to one input of an OR gate 23, The output signal of the comparator 21 is inputted to the other input of this OR gate 23, and OR between both signals is operated to generate clamp pulses whose width Hw1 and Vw1 are slightly narrower than that of H and V sync tip periods H3 and Vw. Consequently, clamp pulses having the width corresponding to the width of sync tips of the video signal are generated, and the overall width of the sync tip of the video signal is effectively used. |
