| 摘要 |
PURPOSE:To erase raster of a desired color through the use of a simple switch of a low dielectric strength, by interrupting signals of the color desired for erase and switching its clamp level. CONSTITUTION:A primary color signal (blue signal in Figure) being a small signal applied to an input terminal 7 is amplified at a differential amplifier 10 and a transistor (TR)11, pedestal-clamp is done at a pulse clamp circuit 16 to regenerate DC components the signal is amplified to a large amplitude at a video output TR17 and applied to the cathode of an electron gun of a cathode ray tube 1. When the raster of this color is desired for erase, switches 22, 23 for raster erasing are set off. Thus, a TR8 is interrupting state and the signal is not applied to the TR11 of the next stage. Since the clamp level goes to ground level with a clamp level adjusting variable resistor 19, the electron gun is cut off, allowing to erase the raster completely. |
