| 摘要 |
A control circuit having large effects of low power consumption in CABC drive is provided. The control circuit performs B/L luminance reduction in eliminating a discomfort in image quality by using the feature value calculation circuit in the video signal. The control circuit comprises a luminance control circuit controlling a backlight luminance according to an inputted video signal and a gradation conversion circuit for converting a gradation of inputted video signal according to a controlled luminance. The control circuit reduces continuously and smoothly the backlight luminance, while the screen area reaches one-pixel white, in case where the all white is inputted as video signal, one-pixel black is displayed in any screen area from a display condition of all white, a rate of screen area displaying one-pixel black is gradually increased, and the video signal is continuously changed until the screen area of all white reaches the one-pixel white. |
| 主权项 |
1. A control circuit comprising:
a luminance control circuit section controlling a backlight luminance according to an inputted video signal; a gradation conversion circuit section for converting a gradation of the inputted video signal according to the controlled luminance; a circuit calculating an average value and a maximal value, representing the average value and the maximal value of gradation of the inputted video signal in one frame of the inputted video signal, respectively; a feature value coefficient set point section setting a plurality of predetermined coefficients; and a feature value calculation circuit section calculating a feature value of the inputted video signal by a polynomial function configured by only four members, consisting of a member multiplying a coefficient by a square of the average value, a member multiplying a coefficient by the average value, a member multiplying a coefficient by the maximal value, and a member multiplying a coefficient by a product of the average value and the maximal value with use of the calculated maximal value, the calculated average value, and the predetermined coefficient,
wherein the control circuit is configured to reduce continuously and smoothly the backlight luminance, in accordance with a continuous change of the inputted video signal from a state in which all pixels included in a screen area are white to a state in which the number of white pixels included in the screen area becomes one by gradually increasing an amount of area displayed in black in any part of the screen area, and the control circuit controls a reduction of the backlight luminance such that an amount of the luminance reduction is always less than or equal to an amount of the luminance reduction calculated by the calculated feature value, in comparison with the calculated amount of the luminance reduction. |
