用于汽车抬头显示器的光学增亮膜设计

为了降低直下式背光的厚度并提升亮度, 设计了一种光学增亮膜。基于Snell定律设计了对单个LED发出光线起均匀照度作用的二维微结构曲线。该微结构曲线是把LED看做理想点光源设计并计算的, 但考虑到实际的LED是一个正方形发光面, 因此对该微结构曲线进行了优化, 提升了它对实际尺寸LED的均匀照度作用。根据LED的排布规律提出了一种正六边形蜂窝拼接排布方案, 并进行了仿真分析。仿真结果表明: 使用光学增亮膜的背光中心亮度提升了172.4%。根据微结构设计结果采用无掩膜直写光刻工艺制作了实际样品并进行了效果测试, 测试结果表明: 中心亮度提升了136.2%, 厚度降低了13 mm。采用本文设计的光学增亮膜可以有效地提高背光亮度同时降低背光厚度, 满足汽车抬头显示器的直下式背光亮度高、体积小的要求。

Abstract

The direct-lit backlight used in an automobile head-up display must have high brightness and a small size. To reduce the thickness of a direct-lit backlight and improve its brightness, an optical brightness enhancement film is designed. First, a two-dimensional microstructure curve for the uniform illumination of light emitted by a single light-emitting diode (LED) is designed according to Snell's law. A microstructure curve is designed and calculated with an LED as an ideal point light source. Based on the consideration that the actual LED is a square luminous surface, the microstructure curve is optimized and its uniform illumination function to a real LED is improved. Then, based on the arrangement of LEDs, a hexagonal honeycomb arrangement is proposed and a simulation analysis is conducted. Simulation results show that the central brightness of use of the optical brightness enhancement film is increased by 173.2%. From the results of the microstructural design, a practical sample is produced by using the maskless direct lithography process and its effect is tested. Test results show that the central brightness is increased by 136.2% and the thickness is reduced by 13 mm. The proposed optical brightness enhancement film can effectively improve brightness and reduce the thickness of backlight units.

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冯奇斌, 武晨晨, 李德华, 王梓, 吕国强. 用于汽车抬头显示器的光学增亮膜设计[J]. 光学精密工程, 2019, 27(7): 1426. FENG Qi-bin, WU Chen-chen, LI De-hua, WANG Zi, L Guo-qiang. Design of optical brightness enhancement film for direct-lit backlight in automobile head-up display[J]. Optics and Precision Engineering, 2019, 27(7): 1426.

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