基于表面微结构的超薄背光模组透镜设计  

Surface Microstructure-BasedUltra-hinBack ht Unit Lens Design

作　　者：冯奇斌[1] 孙启宇 李可敬 王梓 吕国强[2] Feng Qibin;Sun Qiyu;Li Kejing;Wang Zi;Lu Guoqiang(Special Display and Imaging Technology Innovation Center of Anhui Province,National Engineering Laboratory of Special Display Technology,Academy of Opto-Electric Technology,Hefei University of Technology,Hefei230009,Anhui,China;School of Instrument Science and Opto-Electronics Engineering,Hefei University of Technology,Hefei 230009,Anhui,China)

机构地区：[1]合肥工业大学特种显示与成像技术安徽省技术创新中心,特种显示技术国家工程实验室,光电技术研究院,安徽合肥230009 [2]合肥工业大学仪器科学与光电工程学院,安徽合肥230009

出　　处：《光学学报》2023年第7期191-198,共8页Acta Optica Sinica

基　　金：安徽省科技重大专项(202203a05020028)。

摘　　要：根据全反射原理设计了一款基于表面微结构的超薄透镜,由自由曲面将光源出射的光线进行准直,随后利用微米级表面微结构将准直光线反射到底部,再配合底部的反射膜将光线进行二次反射,从而能够在较小的混光距离(OD)下有效增大光斑尺寸。利用边缘光线原理,改善了扩展光源下光线经自由曲面后准直性劣化问题。仿真结果表明,该透镜应用于超薄背光模组时,能够在OD为3mm、距离-高度比(DHR)为15mm的3×3阵列下获得82%的均匀性,相比传统双自由曲面透镜均匀性提升40.7%。该透镜设计方法简单,避免了双自由曲面透镜尺寸较小时加工误差的影响,无需后期大量复杂的优化工作,具有较大的实际应用价值。Objective Because liquid crystal itself does not emit light,a backlight unit(BLU)is needed to provide illumination rays.The brightness and volume of a BLU largely determine the performance of a display.Ultra-thinness has become a popular trend,which requires a light-emitting diode(LED)BLU to minimize its thickness as soon as possible.The direct-lit BLU has the advantages of high brightness,high energy utilization rate,and good uniformity.In order to reduce the production cost,the number of LEDs in the direct-lit module is decreasing,and the distance between LEDs is increasing,which makes the optical distance(OD)larger.Free-form lenses have been widely used in direct-lit BLUs to reduce the thickness and increase the distance-height ratio(DHR).However,when the OD is quite small,the size of the designed lens is relatively small,which results in a large processing error.Furthermore,the illuminance uniformity will be reduced when the lens designed based on the point source method is used for the extended light source.A lot of complicated optimizations are needed to improve uniformity.Therefore,an ultra-thin lens based on the surface microstructure is designed in this paper.The lens first collimates the rays emitting from an LED and then reflects the rays by the microstructures,which can increase the size of the illumination spot during the limited OD.The curvature of the designed surface is small,which can help avoid the influence of processing errors.Methods In this paper,a lens design method based on the surface microstructures is proposed for an ultra-thin BLU that consists of an array of LEDs with a pitch of Apichr X Apichy(Apichr is pitch of direction,and Apichy is pitch of y direction).This design is different from the traditional double free-form surface lens which uses the free-form surface with a large curvature to refract the light at a larger angle.In this paper,the free-form surface is used to collimate the rays from the light source,and then the collimated rays are reflected to the bottom by the surface m

关 键 词：光学设计 超薄背光源 边缘光线理论 全反射 微结构 

分 类 号：TN141.9[电子电信—物理电子学]