SYNCHRONOUS SIGNAL DETECTION CIRCUIT AND METHOD

摘要

PURPOSE: A synchronous signal detecting circuit and a method are provided to be capable of making it possible to accurately detect vertical and horizontal signals from a composite synchronous signal. CONSTITUTION: A reset generator(10) generates a reset signal at the falling edge of the composite synchronous signal. A counter(20) is reset by a reset signal of the reset generator(10) and counts a main clock to generate a 1st to a 4th outputs. A vertical synchronous signal detector(40) inputs the 2nd output of the counter(20) and the external composite synchronous signal and generates a vertical synchronous signal detected by detecting the vertical synchronous signal. A horizontal synchronous signal detector(50) inputs the 3rd and 4th output signals of the counter(20) and the reset signal of the reset signal generator(10) and detects the horizontal synchronous signal of one-hour period.