SYNCHRONIZATION SIGNAL DETECTION CIRCUIT, IMAGE DETECTION CIRCUIT, SYNCHRONIZATION SIGNAL DETECTION METHOD AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide a synchronization signal detection circuit, an image detection circuit, a synchronization signal detection method and a program capable of preventing erroneous detection of the presence or absence of an image signal when the signal level of a composite image signal is lowered or when noise is mixed in the composite image signal.;SOLUTION: The synchronization signal detection circuit is for inputting a separate synchronization signal from a synchronous separation circuit outputting the separate synchronization signal by performing synchronizing separation of input composite image signal, and includes: an adding means for counting and accumulating the number of times of the Low level of the separate synchronization signal within one horizontal cycle; a horizontal synchronization detection means for detecting whether or not the adding result by the adding means is within the horizontal synchronization detection range corresponding to the pulse width of the horizontal synchronization signal; and a vertical synchronization detection means for detecting whether or not the adding result by the adding means is within the vertical synchronization detection range corresponding to the pulse width of the vertical synchronization signal.;COPYRIGHT: (C)2009,JPO&INPIT