PURPOSE: To attain cost-down of a television receiver by allowing a switch having three circuits of R, g, B signals and one circuit of a control signal in total 4 circuits to change over the RGB 8-pin mode and the 21-pin mode to decrease the number of switch circuits.
CONSTITUTION: In changing over a switch 6 to a 8-pin input terminal 1 at the RGB mode, a high level voltage is given to a YS control terminal of a television/RGB switching circuit 5 and the mode is switched forcibly to the RGB mode. Since a collector of a transistor (TR) 11 turns to a low level in this case and a 21-pin signal input switch is turned off, a 21-pin synchronizing signal is not outputted from a video signal switching circuit 28 and a 8-pin synchronizing signal is supplied to an output of the video signal switching circuit 28 via a resistor 27 and a diode 15. When a 21-pin input is given in the RGB mode, the base of the TR11 is grounded forcibly, a 21-pin synchronizing signal input switch of the video signal swiching circuit 28 is turned on and the 21-pin synchronizing signal is outputted.
SUZUKI MOTOYUKI
HARA KENJI
