为减少混光距离进而获得超薄直下式LED背光模组，提出一种具有逆棱微结构的扩散板。对这种逆棱微结构进行了光学理论分析，证明了该结构在降低混光距离方面具有可行性。对逆棱微结构扩散板的光学效果进行了实验验证，并用于813 cm(32 in)LED背光模组。实验结果表明: 该结构扩散板可有效增大灯影光圈，相对无结构扩散板，光圈直径增大约10%[在达到相同混光效果时，具有该结构扩散板的混光高度降低[采用该逆棱微结构的扩散板的背光模组混光高度由13 mm降低至118 mm。采用具有逆棱微结构的扩散板有助于实现LED背光模组的超薄设计。

In order to reduce optical distance (OD) and realize ultra-thin design of direct-lit LED backlight module, this paper proposes a kind of diffuser plate with prism-based micro-structure on the bottom. The optical theoretical analysis is first performed on the prism-based micro-structure, which proves to be feasible to reduce the OD. The prism-based micro-structure is then practically tested and utilized in 813 cm(32 in) LED backlight. Experimental results show that the diffuser plate with prism micro-structure has effect on increasing the diameter of LED shadow by about 10% and reducing OD. The OD of the prototype with 32 in LED BLU is reduced from 13 mm to 118 mm.Such diffuser plate with prism-based micro-structure can help to realize the ultra-thin design.