| 摘要 |
PURPOSE:To automatically display a monitor signal in a television receiver by modulating an external monitor signal with the intermediate frequency of the television receiver, and supplying the output of the said modulation by switching and controlling between the said output and the intermediate-frequency output of television. CONSTITUTION:When a video signal is outputted from an external video source 30, a video detecting circuit 44 outputs a switching-switch signal to a switcher 40 in order to switch the television receiver circuit 10 into monitoring in accordance with the output of a monitor signal, and automatically changes the switcher 40 from its ordinary broadcasting signal input terminal 40a to the monitor input terminal 40b. Therefore, once the source 30 starts operation, the broadcasting signal is no longer supplied to the circuit 10, and the signal from the terminal 40b is displayed on the television screen.
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