| 摘要 |
PURPOSE:To automatically switch to an internal television signal, by detecting the presence/absence of an external television signal. CONSTITUTION:An analog switch circuit 14 using analog gates is used as switch circuits 12, 13 which switch video and audio signals being internal television signals to be applied to a video processing circuit 4 and an audio processing circuit 6. A video signal detection circuit 15 and an audio signal detection circuit 16 detect the presence/absence of external television signals, and only when the external television signals exist, the switch circuits 12, 13 in the analog switch circuit 14 are switched to external input terminals 8, 9 with the output of an OR gate 17, the video and audio signals from an external video tape recorder at that time are applied to the video processing circuit 4 and the audio processing circuit 6, to reproduce the video and audio signals. |
