| 摘要 |
PURPOSE:To constitute so that a channel selecting state of a tuner is not changed in the course of using an external input video signal, by displaying a fact that a video is being used, and also holding an electronic tuner, when the external input video signal is being used. CONSTITUTION:A TV wave signal is amplified by a high frequency amplifying circuit 1, and channel selection is executed by an electronic tuner 2, and it is displayed on an image receiving tube through a video detecting circuit 4 and a changeover switch 30. When the changeover switch 30 is switched to an external input terminal 7 side, an electric power source terminal B+ is connected to a controlling circuit 40, and an output of the circuit 40 is supplied to a channel selecting circuit 10, and also is supplied to a display element 50. In this way, even if any key of the circuit is operated, control is executed so that a data of the operation is not inputted to a forming circuit 20 of channel selecting voltage VC, and holding to the tuner 2 is executed. |
