Video signal processor for TV receiver - detects black component and has suppressor circuit for period exceed line suppression interval modifying wave

摘要

The video signal processing circuit is for use on a television receiver, where the signal level is detected which is nearest to black during the video period. That level is chosen as the cut-off level of the cathode ray tube and used to prevent fluctuations in the black section of the image. The input video signal is fed to a suppressor circuit (2) for a period which is longer than the normal image line suppression interval. During that period it is altered in a predetermined direct voltage level higher than the threshold level, providing an output signal with modified wave form. The suppressor circuit(2) is followed by a minimum level hold circuit (4), a comparator (5) and a level fixing circuit (6).