Frame synchronizer and a signal switching apparatus

摘要

An external color frame is synchronized with a local color frame without producing a pixel position error. A frame synchronizer synchronizes a frame from an external television signal with that of a local television signal. A wide screen oriented high definition television signal is used as the external television signal, the image quality of which is improved by adding a support signal to the main screen signal. A memory is provided to receive and store the external television signal and the external signal is read from the memory after a predetermined time passes when the frame difference between the external and local television signals is at least one frame. In this instance, only the support signal in the readout of the external television signal is corrected by a low pass filter in order to match the pixel position of the support signal to that of the main screen signal.