| 摘要 |
A brightness control apparatus for a video display appliance which keeps the brightness of the picture uniformly over the whole screen by determining the amplification rate of the video signal to be displayed at the corners of the screen relatively higher than that to be displayed at its center. The apparatus includes a parabolic wave generator for generating horizontal and vertical parabolic waves corresponding to horizontal and vertical sync signals separated from the video signal, first and second amplifying sections for amplifying the horizontal and vertical parabolic waves outputted from the parabolic wave generator with predetermined amplification rates, respectively, and a signal superimposing section for superimposing the amplified horizontal and vertical parabolic waves with a DC voltage provided from a variable resistor for adjusting the amplification rate of the video signal and providing a superimposed signal to a video amplifying section as an amplification-rate control signal of the video amplifying section.
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