掠射式双面三棱柱阵列微结构扩散板的研究

Research of Grazing Incidence Diffuser with Microstructure of Double-Sided Triangular Prism Arrays

研究了一种适用于无导光板侧入掠射式发光二极管(LED)平板灯的双面三棱柱阵列微结构扩散板。通过菲涅耳公式理论分析了双面三棱柱阵列增透原理,利用光线追迹软件TracePro模拟仿真了三棱柱阵列深宽比和三棱柱底边宽度对扩散板透射率的影响。模拟结果表明,入射面的透射率随深宽比的增大而增大,对于聚甲基丙烯酸甲酯(PMMA)和聚碳酸酯(PC)光学材料,当深宽比为0.5左右时透射率达到最大,并不再随深宽比增大而改变。出射面三棱柱阵列微结构深宽比在0.5附近由于两次全内反射导致透射率出现一个下降区域,而三棱柱阵列间距对扩散板的透射率影响很小,结果表明优化后的三棱柱微结构阵列扩散板对掠射光线的透射率可达93%。

A grazing incidence diffuser with double-sided triangular prism arrays is researched, which is suitable for edge-lighting light emitting diode （LED） flat panel light without light guide plate. Based on Fresnel equations, the anti-reflection principles of triangular prism arrays are analyzed. The influence of parameters of the triangular prism arrays, i.e. the ratio of depth to width and the bottom width, on the diffuser transmittance is investigated by using the simulation of ray tracing software TracePro. Simulations reveal that the transmittance of entry surface increases with the ratio of depth to width, both for polymethyl methacrylate （PMMA） and polycarbonate （PC）. The transmittance achieves the maximum while the ratio of depth to width is about 0.5, and keeps invariant when the ratio increases. The transmittance of exit surface decreases when the ratio of depth to width is close to 0.5, because the light has been total reflected twice in the diffuser. The results show that the transmittance of grazing incident ray can be up to 93 % in the optimized diffuser.