摘要
针对头盔显示器(HMD)液晶像源的特殊要求,选择了一款小尺寸、高光效的发光二极管(LED)作为背光光源。基于此LED的光强分布曲线,利用非成像光学理论设计了双自由曲面透镜阵列,以期进一步提高背光光效。首先对单个LED设计了3款不同半径的双自由曲面透镜,形成了亮度均匀的圆形光斑。然后对单个透镜进行切割,形成矩形光斑,并用4个矩形透镜拼接成透镜阵列。选择了效果最优的透镜进行了加工和测试。结果表明:与传统的采用两层扩散膜的背光结构相比,采用透镜阵列和两层扩散膜后的背光的光能利用率提高了13.94%,背光亮度提高了96.4%,非均匀性由23.8%略提高到23.1%,半亮度视角由37°降低到19°。用设计的透镜及其阵列对LED光源发出的光线进行准直,易形成高亮度的均匀矩形光斑,满足头盔显示器液晶像源背光的要求。
For the special requirements of the liquid crystal image source of a Helmet-Mounted Display （HMD）, this paper chooses a smaller size and higher effective Light Emitting Diode（LED） as the backlight source. On the light intensity distribution curve of the LED, a double-freeform-surface lens array was designed based on the no-imaging optical theory to improve the backlight efficiency of the source. Three lens arrays with different radii were firstly designed to form a round light spot with uni- form lightness. Then single round lens was cut to become a rectangular light spot and 4 lenses were combined to become a lens array. One lens with the best simulation results was selected to be fabrica- ted and the backlight unit with such lens array was tested. The measurement results show that com- pared with the common backlight source, the luminous efficiency of the backlight source with 2 diffus-ers and the lens array increases by 13.94%, the luminance increases by 96.4%, the non-uniformity is slightly improved from 23.8% to 23.1%, and the viewing angle of full width of half maximum decrea- ses from 37 degree to 19 degree. The designed lens array was used to collimate the light from LED sources, satisfying the requirements of the LED backlight in LC imaging engine of the HMD.
出处
《光学精密工程》
EI
CAS
CSCD
北大核心
2016年第8期1884-1893,共10页
Optics and Precision Engineering
基金
安徽省科技攻关项目(No.1501021043)
