LCD直下式背光LED间距、灯腔深度及均匀性设计

为满足直下式LCD显示亮度不均匀性小于20%与背光设计薄型化要求,建立阵列LED背光及其上方平面照度的数学模型。根据单颗LED的发光特性,推导出阵列LED上方平面的照度分布。结合亮度不均匀性公式,采用Matlab软件对阵列LED间距、LCD灯腔深度、阵列LED上方平面照度不均匀性之间的关系进行定量研究。通过对LED间距为8.8 mm的照度不均匀性分析,结果显示灯腔深度为10 mm可满足不均匀性小于20%的要求。然后对任意阵列LED间距情况下的照度不均匀性进行计算,结果表明,灯腔深度与LED间距之比约为1.1时,能满足薄型化设计要求和上述显示不均匀性要求。

LCD Direct-type Backlight LED Space, Cavity Depth and Luminance Non-uniformity Design

In order to design a thin direct backlight with nonuniformity less than 20%, an illuminance mathematic model of a M×N LED array is conceived, and the relationship of LED array space, cavity depth and luminance non-uniformity are studied using Matlab tools. Firstly, a criterion for backlight non-uniformity is shown, and the illuminance mathematic model on a specific plane which is parallel to LED array is built based upon the radiant characteristic of LED. Then, simulation and analysis of reasonable cavity depth for specific and arbitrary LED space are made. The results indicate that the ratio of cavity depth and LED space about 1.1 is perfect with luminance non-uniformity no more than 20%, which meets the requirement of both thin backlight design and luminance non-uniformity.