Patent ID: 8212925

Claim:
A sync separation circuit separating a synchronizing signal from a video signal containing the synchronizing signal, the circuit comprising: a minimum level detecting circuit which detects a minimum level of a video signal; a sync tip level detecting circuit which detects a sync tip level in the video signal; a pedestal level detecting circuit which detects a pedestal level in the video signal; and a slice level control circuit which sets a slice level to an initial slice level corresponding to the minimum level and subsequently, based on the synchronizing signal obtained after sync separation utilizing the initial slice level, detects the sync tip level and the pedestal level and sets the slice level to a subsequent slice level corresponding to an intermediate value between the sync tip level and the pedestal level, wherein, upon detecting a vertical synchronization signal, the slice level control circuit determines that the subsequent slice level is inappropriate, the slice level control circuit sets the slice level to a new slice level based on the minimum level, and wherein, upon detecting a vertical synchronization signal, the slice level control circuit determines that the subsequent slice level is appropriate, the slice level control unit sets the slice level to a new slice level corresponding to the subsequent slice level made closer to a target slice level using a predetermined time constant, wherein the target slice level corresponds to an intermediate value between the sync tip level and the pedestal level.