US Patent 7483626 Portable DVD player and optical disc player

A portable DVD player or optical disc player instructs an interior selection state to an output selector and outputs an internal signal to an output terminal. Whether a lock slide switch is in the exterior selection state or in the interior selection state is displayed via OSD for a first or second time period. It is possible to let the user check whether the lock slide switch is in the exterior selection state or in the interior selection state without providing a synchronization detection circuit for detecting the synchronization of a video signal output to an output terminal and an OSD image generation circuit for generating a video signal corresponding to an OSD image overlaid on the image of a video signal before the output terminal.