| 摘要 |
PURPOSE:To render a RGB signal change-over circuit more simple and to prepare it at a low price by performing a parallel connection of both external and internal RGB signals. CONSTITUTION:When an external RGB signal is selected, an image signal is intercepted after closing switches 8 and 9. Consequently the RGB signals (R1, G1, B1) can't output and only the external RGB signals (R2, G2, B2) are inputted to an RGB signal amplification circuit 6. In the opposite way when an internal RGB signal is selected, it allows switches 8 and 9 to become open and the internal RGB signal (R1, G4d1, B1) are inputted to the RGB signal amplification circuit 6. An external input signal of the switch 8 is applied to a base of emitter-follower transistor 12 and to its emitter the internal RGB signal's R1 signal shall be applied. A transistor 11's collector is connected to the base of transistor 12 and the emitter is connected to an earth while a selection con trol signals of RGB signal is applied to the base.
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