Video signal synchronizing apparatus

摘要

An apparatus for performing a generator locking for a video signal including a first video processing circuit for processing an input video signal, an expansion module having a second video processing circuit and a delay circuit having a delay time introduced by said second video processing circuit, a synchronizing signal separating circuit for separating a synchronizing signal from an external reference signal, and a phase-lock loop circuit for generating a reference control signal for said first video processing circuit as well as a phase comparison signal. Said phase comparison signal is fed-back to the phase-lock loop circuit by means of said delay circuit. Although the expansion module is connected to the expansion slot, a phase of a finally obtained video signal is remained in a same fixed relationship as a phase relationship when a connection board is connected to the expansion slot. <IMAGE>