CIRCUIT AND METHOD TO OUTPUT SYNCHRONIZING SIGNAL, RECORDING MEDIUM AND DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To quickly respond to the change in the frequency of vertical synchronizing signals. SOLUTION: A terminal 1 is supplied with vertical synchronizing signals (independent vertical synchronizing signals) which are independently inputted. A terminal 2 is supplied with vertical synchronizing signals (separated vertical synchronizing signals) which are separated from composite synchronizing signals. Frequency measuring circuits 32 and 33 respectively measure the frequencies of the independent vertical synchronizing signals from the terminal 1 and the separated vertical synchronizing signals from the terminal 2 and supply the measured frequencies to a CPU16. Based on the frequencies of the independent and separated vertical synchronizing signals, the CPU16 controls switch 31 so that either one of the independent vertical synchronizing signals or the separated vertical synchronizing signals is outputed as the vertical synchronizing signals (final vertical synchronizing signals) which are finally used for the display of video.