Circuit for controlling delay time between luminance and chrominance signals

摘要

A circuit for automatic control of delay time between luminance and chrominance signals is disclosed. The delay time control circuit of the present invention comprises: a clock pulse generator that passes a certain number of clock pulses during a period of time between the positive-going edge of the horizontal synchronizing signal from a horizontal synchronizing separator and the leading edge of the color burst signal from a color burst signal separator; a comparator that compares the number resultant clock pulses to a reference value and determines which signal (the luminance or the chrominance signal) is delayed and the length of the delay time; a luminance delay circuit and a chrominance delay circuit that delay the luminance and chrominance signal respectively according to outputs of the comparator; and a luma/chroma mixer that mixes the delayed luminance and chrominance signals. Therefore, the present invention improves picture quality by adjusting the delay time between the luminance and chrominance signals which occur in various kinds of VTR's and video tapes.