| 摘要 |
<p>PURPOSE:To reproduce correctly hue even when a luminance signal of a picture is changed by setting an upper and a lower limit reference voltage in R, G, B signal processing systems based on the luminance signal in a liquid crystal color television receiver. CONSTITUTION:The luminance signal Y transmitted from a video signal processing circuit is amplified respectively at amplifiers 51-71. The amplifiers 51-71 are set to the amplification factor in response to the corresponding color signal. Thus, the luminance signal Y inputted to, e.g., the amplifier 51 is amplified into the same amplitude as the R signal. Each luminance signal after amplification is inputted to low pass filters 52-72, an average level is detected and outputted to level shifters 53, 54-73, 74. Each level shifter shifts the inputted mean value level to upper and lower level to form the upper limit and lower limit reference voltages, which are given to an A/D converter 55. Since each color signals is controlled depending on the change in the luminance signal of the picture, the hue of the picture displayed on the liquid crystal panel is reproduced correctly.</p> |
