| 摘要 |
A control circuit is provided in a video display system that is responsive to the horizontal and vertical deflection signals to produce a shading signal including a plurality of signal components corresponding to independently variable linear and higher order functions (preferably conic functions) of the deflection signals, to modify the video signal and control the intensity of the video display at locations that are functions of the excursions of the sweep signals along their time bases. In the manually controlled embodiment of shading, a differential amplifier is employed to combine the video signal with the shading signal to produce a shaded video signal and to selectively control the intensity in the video display. The system may be employed in conjunction with a window amplifier to independently control the position of the various components of the video signal on the gain curve of the window amplifier whereby to alleviate problems of burn-out or excessive darkness of various elements of the display. In an automatically controlled embodiment of shading, the video signal is combined with, in a disclosed embodiment, nine different shading voltages each relating to a different area of the screen for controlling shading in each such area.
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