| 摘要 |
PURPOSE:To improve operability by supplying external RGB signals to the image receiving section when a TV/external switching circuit selecting a signal sent to an image receiving part is detected by a detection circuit with horizontal synchronization signals. CONSTITUTION:When turning on the power source of an external equipment connected with a TV receiver through a a 8-pin RGB input terminal group 1 horizontal synchronization signals are inputted to the 7th pin and the collector of a transistor 12 is turned over to the high level, thereby switching circuit 15 is switched automatically to the external RGB impressed to the 2nd- the 4th pins. When turning on the power source of the external equipment, since horizontal synchronization signals inputted in the 7th pin are eliminated and, the base of the transistor 10 returns to the low level, the transistor 10 is turned off. Thereby the transistor 12 is turned on and its collector becomes a low level,the control terminal of the switching circuit 15 becomes the low level. The switching circuit 15 comes to a TV mode in which TV signals appear on the display part.
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