Research Of Regional And Dynamic Dimming Technology For LED Backlight

With the significant advantages of thin thickness,non-radiation and low energy consumption etc,Liquid Crystal Display(LCD)technology,witch is based on LED backlight,has replaced the Cathode Ray Tube(CRT)technology and becomes the mainstream flat-panel display technology.However,the traditional LCD technology still have many shortages which need to be improved,including the problems of light leakage,low image contrast,relatively high power consumption and so on.Therefore,the further research of reducing power consumption and improving image's quality have become the focus of the backlight display technology.This thesis mainly studied a new regional and dynamic LED backlight dimming technology.And it mainly includes three aspects as the follows:(1)Aiming at the defects of the traditional regional and dynamic dimming algorithm,A deep study on the application of the traditional algorithms on the two types of LED backlight was made,from the point of view of the combination of theory and practice.Meanwhile,some shortages of the traditional algorithms was pointed out,such as the incomplete key influence factors,a poor compromise between low power consumption and good image quality.That had set a good foundation for the more comprehensive analysis of the key influence factors and proposed a more excellent dimming algorithm.(2)A new regional and dynamic dimming algorithm was proposed,which was based on optimization and the steepest descent method.The algorithm studied each key influence factor which impacted dimming performance,and extracted the application form of the factors in the algorithm according to the actual demand of dimming in this paper.Then,we the objective function for optimization and optimization model was determined based on each factor,while the model's complexity also being cut down.After that,by using the steepest descent method to optimize the solution and obtained a group optimized backlight brightness value.According to optimized backlight brightness value to do the liquid crystal compensation.The advantage of this algorithm is that the error weighted variable which based on visual perception was applicated in the optimization model,which reduced the error between human visual perception and actual physical display,effectively improved the user's subjective feeling effect.At the same time,the power restriction factor also was added to the optimization problem,which could be used to regulate the level of power,also made the algorithm more flexible and universal.(3)A new evaluation index was proposed,which was based on the color space of CIE 1976 L*a*b*,named LABPSNR.Also on this basis,simulation tests and practical tests was carried out based on the proposed algorithm,used MATLAB simulation software and model machine.Two groups of simulation test results proved that the decrease of the color optimization model's complexity is feasible,and the improvement of the displayed quality compared to the traditional algorithms.The experimental results show that,when has the same power level with average value algorithm,the proposed algorithm's average LABPSNR value increased 39.8%compared to the average value algorithm,increased 41.8%compared to the mean square root algorithm,increased 20.4%compared to the Inverse of Mapping Function(IMF)algorithm.The actual test results further show that the proposed algorithm has a better compromise between reducing the power consumption and improve the image quality,compared to the traditional algorithms,also can effectively reduce the power consumption of the display 18.27%average.