| 摘要 |
PURPOSE:To mix picture signals in excellent way, by providing a ratio adjusting circuit to a graph signal superimposing device and making the ratio of colors of the superimposing signal coincident with that of a chrominance signal of a TV picture signal so as to make the color ratio of the TV picture signal of an analog system coincident with that of a digital system video signal. CONSTITUTION:A character/graph signal superimposing device 10 is inserted between a color TV receiver 11 and a driver 12 driving a CRT13. The device 10 consists of a basic circuit 15, which is provided with an amplifier circuit 22 comprising PNP and NPN transistors 16, 17, and the 1st control circuit 23 connected to the base of the TR17 being an output stage of the amplifier circuit 22, and a chrominance signal (R'+G'+B') representing a character or a graph is inputted to the circuit 23. Further, the ratio adjusting circuit 26 is provided between the 2nd control circuit 24 inputting the chrominance signals R', G', B' and an output of the amplifier circuit 22. Then, the ratio of chrominance signals between the TV picture signal of the analog system and the digital system video signal is made coincident with each other so as to mix the picture signals in excellent way. |
