| 摘要 |
PURPOSE: A brightness control apparatus for on screen displays is provided to maintain brightness of screen of on screen display optimum even when the contrast of the main screen is lowered. CONSTITUTION: A brightness control apparatus comprises an inverter(270) for inverting the contrast voltage input from an external source to adjust contrast; a variable limiter(260) having, as an output level, the contrast voltage inverted by the inverter, and where on screen display signal is input; a mixer(210) for synthesizing the on screen display signal which has a level converted by the inverter and variable limiter, and a main image signal; a pre-amplifier(220) for amplifying the signal synthesized and output from the mixer, in accordance with the contrast voltage; and a buffer(250) for amplifying the on screen display signal output from the variable limiter and the main image signal.
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