| 摘要 |
PROBLEM TO BE SOLVED: To improve a displaying picture quality by reducing DC voltage components generated by the voltage shift of a liquid crystal applying waveform varying by a display signal voltage. SOLUTION: Concerning a common electrode driving signal Vcom, a frame inversion signal FRP outputted by an LCD controller 8 is amplified by a common electrode driving amplifier 9 to adjust its central voltage by a variable resistor 10 and an APL signal corresponding to an average voltage in one frame period of a video display signal outputted by an RGB decoder/inversion amplifier 101 is amplified by an amplifier circuit 104 and connected via a resistor Rc, to set the DC level Vc of the common electrode driving signal. The amplitude characteristic of the circuit 104 is set to the APL signal to match with the varying characteristic of a DC level with respect to the APL signal with a deviating quantity to the negative voltage side of a liquid crystal applying voltage waveform made by the variation of a diving voltage by raising the DC level when the APL signal is large and lowering the DC level when the APL signal is small.
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