SYNCHRONOUS SIGNAL SEPARATION CIRCUIT

摘要

To prevent errors caused by jitters and delays, in separating and fetching the synchronous signal from a video signal to which a synchronous signal has been added a sync-on-green signal is fetched from a branch line branched on the way of a signal line connecting the output pin of a video amp and an A/D converter and is connected to the plus side input pin of a comparator. That is, to the plus input pin of the comparator there is input a voltage corresponding to a brightness signal amplified by the video amp and also shifted by an offset voltage. Also, to the minus input pin of the comparator there is input a threshold voltage for detecting the falling edge of said synchronous signal. If the voltage corresponding to the video signal is less than the threshold voltage, the comparator will determine that the synchronous signal was detected and output a logic low level (L) signal.