| 摘要 |
PURPOSE: A brightness uniformity controlling circuit of a display apparatus is provided to maintain a brightness of a total cathode ray tube screen by controlling the brightness according independent variables on the basis of a center of the screen. CONSTITUTION: A brightness uniformity controlling circuit of a display apparatus comprises a parabola waveform generating part(120) which generates a parabola waveform according to data to each slope from a micro computer(100) and a horizontal/vertical signal fed back from a deflection circuit part(150). The parabola waveform generating part(120) consists of a horizontal parabola waveform generating part(121), a vertical parabola waveform generating part(123) and a parabola waveform mixing part(125). The horizontal parabola waveform generating part(121) outputs a horizontal parabola waveform according to a horizontal signal(H) fed back from the deflection circuit part(150), a horizontal output signal(H.OUT) from the micro computer(110), and the data to slopes of right and left parabola waveforms of a screen. The vertical parabola waveform generating part(123) outputs a vertical parabola waveform according to a vertical signal(V) fed back from the deflection circuit part(150), a vertical output signal(V.OUT) from the micro computer(110), and the data to slopes of up and down parabola waveforms of the screen. The parabola waveform mixing part(125) mixes the horizontal and vertical parabola waveforms to output the mixed waveform to a video pre amplifier(130).
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