| 摘要 |
PURPOSE:To eliminate the need for the adjustment of a device except the adjustment of pulse cancellation adjuter and to simplify the switch operation, by providing a means superimposing an AC signal, to a gain control terminal of a gain control amplifier placed at the post-stage of a circuit mixing a pre-blanking pulse to an image. CONSTITUTION:Pre-blanking pulses PRE.BL from a pre-blanking input terminal 19 are mixed to output signals of preamplifiers 1, 7 and 13 of red, green and blue color respectively at pulse cancelling adjusters 3, 9 and 15. This output is applied to gain control amplifiers 4, 10, 16, amplified at a gain determined with gain control adjusters 20-22, and a video signal is outputted to output terminals 6, 12 and 18 via pedestal control amplifiers 5, 11 and 17. The adjuters 20-22 are connected with an AC superimposing signal generator 25 via a capacitor 23 and a switch 24 to superimpose AC signals to the gain control terminal of the amplifiers 4, 10 and 16. The adjustment of the switch is made easy without shifting the adjusting point of the adjusters 20-22. |
