导光板底面熔合微棱镜出射亮度规律研究

基于导光板底面直接熔合微棱镜取代目前背光系统平面反射膜和网点两层结构,推导了棱镜底角和出射亮度方向角之间的关系,提出导光板出射亮度方向角与棱镜远近光源底角的解析公式.用LightTools软件对导光板进行建模仿真,通过改变棱镜两个底角,得到出射亮度峰值方向和底角之间的变化规律.理论值与模拟仿真值基本符合,为背光模组一体化的研究提供理论和实验依据.依据上述规律,设计出一体化导光板结构,其中,微棱镜近光源角为86°,远光源角为37°,亮度达到现行3M背光系统指标.     

一种圆环LED侧入式背光模组设计

侧入式背光板能有效地减少显示背光模组的厚度和背光所需的LED光源数目,为获得均匀照度的侧入背光模组,介绍一种圆环侧入式导光板结构。推导导光板中网点的设计规律,得到圆环侧入式导光板的网点大小的分布函数。利用VBA语言编程在CAD中生成网点分布,结合软件模拟分析,验证了导光板显示区域中光照亮度均匀性达到90％以上,满足了侧入式背光模组中圆环形导光板工程设计上的要求。     

基于DMD微光刻的导光板模板的制作方法

提出了一种基于数字微反射镜(DMD)微光刻的导光模板的制作方法.导光板的网点单元图形由DMD输入,经过缩微光学成像系统缩微后,在光刻胶干板上逐单元网点曝光,再经过显影、微电铸得到导光板模板,在PC薄板材上用微纳米压印制成导光板,厚度仅为0.381 mm.采用自行研制的SVGwriting-DMD激光直写系统,图形的最小分辨率为2 μm,DMD微光刻法无需掩膜版,可实现不同形状、大小、微结构的单元网点图形及网点的排布,便于大幅面的导光板模板的制作.     

导光板散射网点的布局与出光均匀性的研究

从背光模组的基本结构出发,通过理论分析确定了影响导光板散射网点排布的公式,证明了散射网点的排布规律对背光模组出光均匀度有影响。对一款背光模组商品建立了简化模型,通过光学软件TracePro模拟分析以及实验验证,证明了背光模组商品的出光均匀度还有提升的可能性。在此基础上,又重点分析了散射网点行间距的变化值,散射网点直径和散射网点初始行间距对导光板出光均匀度的影响。经过反复仿真模拟,取得了一组参数值,可以使优化后的导光板出光均匀度比背光模组商品的出光均匀度好。研究的结论可作为导光板散射网点设计的参考,对背光模组的设计具有指导意义。     

手机侧背光照明导光板设计模拟

 为了提高手机侧背光照明导光板的亮度及亮度均匀性,对上表面为41 mm×26 mm的楔形导光板进行了模拟仿真,并对导光板底面不同的印刷式散射网点排布、不同的楔形导光板底面角度及不同的球缺形凸包网点排布进行了研究。结果显示,导光板底面排布印刷式散射网点时,导光板上表面亮度分布的均匀性较差,而出射光通量的百分比小于26%;当导光板底面排布球缺形凸包网点时,导光板上表面亮度分布的均匀性得到提高,出射光通量的百分比提高10%。楔形导光板底面角度81°时的出光效果优于85°时的效果。     

侧光式LED背光源的导光板网点设计

导光板是背光模组的关键组件,决定了出光效率以及出光均匀度。以2颗LED灯的侧背光为例,建立其相应模型,并运用光学理论推导出导光板网点排布规律,得到一个形式简约的公式,并将其进行扩展应用,推出了多颗灯情况下的导光板排布规律;另外将其进行等效应用,得到了线光源情况下的导光板的排布规律。     

侧入式LED背光模组中光耦合模块的设计与实现

现有的液晶显示器(LCD)背光模组大多采用侧入式发光二极管(LED)作为背光源,其要求导光板厚度始终大于LED发光截面宽度。为解决这一问题,提出一种用于侧入式LED背光模组的自由曲面光耦合结构,包括浸入式准直透镜与自由曲面反射器,光源出射光先由浸入式准直透镜收集并准直,再经自由曲面反射器反射并聚集到导光板入光面。利用斯涅尔定律、微分几何法以及等光程原理对该模块进行设计,并通过光学仿真验证设计的可行性。实验结果表明,当采用有效发光面积为0.4 mm×0.4 mm的LED芯片作为光源时,导光板厚度减少0.6 mm,导光板入光面处光能利用率达到96.23%,相对于传统结构,光线利用率提高11.22%。该光耦合模块实现了背光模组中导光板的薄型化,同时改善了导光板入光面处光热点现象。     

集成化导光板下表面微棱镜二维分布设计

集成化导光板下表面微结构分布是影响背光模组出射光均匀性的关键因素,因此是背光模组设计的重点之一.本文针对微棱镜一维分布设计中存在的大面积同一性影响背光模组亮度均匀性的问题,提出一种集成化导光板下表面微棱镜二维分布的设计思想,以提高背光模组的亮度均匀性.利用光学软件Lighttools对5.0英寸集成化导光板下表面微棱镜结构的较佳二维分布进行优化探索,通过与较佳的一维分布仿真结果对比分析可知,优化后的二维分布模式下,背光模组的光能利用率、照度均匀性、亮度均匀性分别达到92.03%,87.07%和91.94%,满足行业标准;其中,照度均匀性比一维分布提高了10%;同时,从亮度图观察,背光模组的整体亮度均匀性得到了有效提升.该研究结果对于背光模组轻薄化、集成化开发具有一定的参考价值.     

量子点背光技术的研究进展

量子点材料因具有发光波长可调,色度纯,量子效率高等优异特性而受到广泛关注,在光致发光高色彩显示方面有着巨大的应用潜力。本文综述了量子点背光技术的研究进展,主要对比了QDs On-Chip、QDs On-Surface及QDs On-Edge 3种量子点背光主流技术的基本原理及结构,并分析了它们在液晶显示领域的应用,未来前景及面临的挑战;然后介绍了几种新型的量子点背光技术,并对两种量子点背光新技术进行重点说明:一种是采用低温注塑成型工艺将量子点与高分子材料均匀混合为一体,用于制备直下式背光的量子点体散射型结构扩散板;另一种新技术是采用丝网印刷或喷墨打印工艺将量子点转印至导光板表面,形成应用于侧入式背光的量子点网点微结构导光板。这两种背光都具有制备工艺简单、成本低、生产效率高等特点,对高色域液晶显示的研究及发展意义深远。     

侧入式导光板的激光微加工技术的验证研究（英文）

从设计、仿真与加工入手研究液晶背光模组中侧入式导光板的激光微加工技术.通过光学软件构建导光板的光学结构并采用蒙特卡洛光线追迹方法进行模拟仿真,结果表明具有渐变密度分布的微结构能够提供高均匀性的光输出.基于仿真结果,运用激光微加工技术进行验证设计.激光微加工获得的微结构在100倍光学显微镜放大测量下尺寸约为30.14μm,接近于设计值30μm,同时对单个微结构的3D表面形貌特征进行分析.十组采用激光微加工技术与丝网印刷技术加工的导光板分别安装至侧入式背光模组样机中进行对比.对比结果显示,激光微加工的导光板相比于传统的丝网印刷技术具有更好的光学均匀性和更低的色差,均匀性提高了6.2%,而色差下降了0.002 7.激光微加工技术快而简单,且整个加工过程是完全环保的,具备高性能、自动化生产和易于薄型化的优点.     

光散射聚合物导光板的材料参数设计

光散射聚合物(HSOT)导光板与传统导光板相比具有亮度更高均匀性更好等优点,其性能受材料的影响十分明显。通过蒙特卡罗方法进行光学仿真模拟考察不同材料的导光板照明光线的均匀性差别,研究了光散射聚合物导光板的光学性能受其中掺杂粒子的材料折射率、粒径、浓度的影响规律。通过比较不同材料参数的聚合物导光板的光学性能差别,总结出光散射聚合物导光板的材料设计方法。     

Prism-pattern design of an LCD light guide plate using a neural-network optical model

This paper proposes a neural-network optical model for a backlight module of a liquid crystal display (LCD) to expedite the design of the light-scattering prism-pattern of its light guide plate (LGP). First, the prism surface of a light guide plate is divided into several equal regions. Then the neural-network optical model is implemented using a back-propagation neural network to establish the relationship between the distribution density of the prism pattern and the exiting-light luminance of the LGP at each region. The input–output patterns for the neural network training and verification are generated using orthogonal arrays and ASAP simulation. Then a for-loop computational algorithm is executed to search an approximately optimal distribution density of the prism pattern using the neural-network optical model such that high luminance uniformity is achieved. It is demonstrated by the case study of a 13 in. LCD backlight module that luminance uniformity could reach 93.1%. Thus it can be concluded that the developed neural-network optical model effectively expedites the LGP prism-pattern design.     

A polarized laser backlight using a zero-zero-birefringence polymer for liquid crystal displays

We have demonstrated a polarized laser backlight for liquid crystal displays and have investigated its basic polarization properties. To maintain the state of polarization of light propagating through the light-guide plate (LGP) of the backlight, we fabricated the LGP by injection molding of a zero-zero-birefringence polymer, poly(methyl methacrylate-co-2,2,2-trifluoroethyl methacrylate-co-benzyl methacrylate) (52: 42: 6 by mass) that is free of both orientational and photoelastic birefringence. The degree of polarization of light from the resulting backlight (average: 92.4%) was much higher than that from a backlight with a polycarbonate LGP (average: 8.0%) in the defined effective range of the backlight. A laser speckle pattern was observed but the speckle contrast on the output surface of the backlight was reduced from 68 to 10% by vibrating a diffuser sheet situated in front of the output surface of the LGP. We also manufactured a white surface light source [chromaticity (value: x, y) = (0:310, 0:314)] by mixing the outputs from three primary-color-emitting lasers in the backlight.     

Ultra slim and bendable backlight system with a unified component for liquid crystal display applications

Our research group has developed an ultra slim and bendable backlight system, which was manufactured by a continuous roll-to-roll process, with a unified component for liquid crystal display (LCD). This backlight system, which has a thickness of 0.26 mm, is simply composed of a light guide film and an optically patterned film made of photocurable resin with micro particles, consequently it does not require any additional optical films such as prism sheets or diffuser. In addition, we have developed a new light guide component which is composed of bundled optical fibers in order to collimate light from the light source to the light guide film. We found that the backlight system could be radiated uniformly across the LCD surface whether plane or curved, and we were able to realize an advanced LCD with good flexibility, high efficiency and high productivity.     

Application of an LM-neural network for establishing a prediction system of quality characteristics for the LGP manufactured by CO2 laser

The light guide plate (LGP) is a part of a backlight module, which evenly spreads light sources in a liquid crystal display (LCD) to eliminate total reflection. Light is transmitted into the LGP, where it is reflected, scattered, and refracted due to the microstructure, which allows light to uniformly enter the panel. Therefore, the design of an LGP micro-structure and processing mode is important for light transmission in an LCD. This study used a CO₂ laser to fabricate a polymethyl methacrylate (PMMA) LGP, applied a Taguchi orthogonal array to set up the experiment, and utilized the data to establish a prediction system. Backpropagation (BP) neural network and the Levenberg–Marquardt (LM) algorithm were integrated to establish a prediction system for LGP processing by CO₂ laser, with the controlling factor as the input parameter, and quality characteristics as the output parameters. After learning and training the network, the prediction error rate of the system was controlled within 5%, demonstrating good predictive validity.     

Simple liquid crystal display backlight unit comprising only a single-sheet micropatterned polydimethylsiloxane (PDMS) light-guide plate

A simple liquid crystal display (LCD) backlight unit (BLU) comprising only a single-sheet polydimethylsiloxane (PDMS) light-guide plate (LGP) has been developed. The PDMS LGP, having micropatterns with an inverse-trapezoidal cross section, was fabricated by backside 3-D diffuser lithography followed by PDMS-to-PDMS replication. The fabricated BLU showed an average luminance of 2878 cd/m(2) with 73.3% uniformity when mounted in a 5.08 cm backlight module with four side view 0.85cd LEDs. The developed BLU can greatly reduce the cost and thickness of LCDs, and it can be applied to flexible displays as a flexible light source due to the flexible characteristic of the PDMS itself.     

A novel backlight unit for volume-holographic optical elements-based time-multiplexed three-dimensional displays

In volume-holographic optical elements (VHOEs)-based time-sequential three-dimensional (3-D) displays, two reference beams generated from a backlight unit (BLU) illuminate VHOEs, and from which object beams satisfying the Brag condition are then diffracted. These beams form a pair of alternating light fields for stereo 3-D view. Since this system operates based on diffraction optics, its performance highly depends on the degrees of collimation and uniformity of the reference beams. Thus, a new BLU system to generate uniformly-collimated reference beams for the VHOEs-based 3-D display is proposed by combined use of a light-guide-plate (LGP) grooved with an array of angle-variant flat-top prisms, and two LED light sources attached with reflection-type beam collimators. Simulation results with LightTools 7.1 show that the average full-width at half maximum (FWHM), backshift ratio and intensity uniformity of the LGP output beam of the proposed system have been significantly reduced down to 2.8° and 0.4%, and increased up to 90.9%, respectively, from the values of 51.8°, 26.5% and 24.5% of the conventional system. They represent 18.5-, 66.3- and 3.7-fold improvements of those values in the proposed system, respectively. These successful results confirm the feasibility of the proposed system in the practical VHOEs-based 3-D display.     

Light-guide plate using periodical and single-sized microstructures to create a uniform backlight system

Light-guide plates (LGPs) with aperiodic or size-varied microstructures are widely used in edge-lit light-source backlight systems for their high uniformity. In this Letter we designed a LGP with periodic and single-sized microstructures and analyzed the relationship between the holistic arrangement density of the microstructures and the uniformity. By controlling the holistic arrangement density of the microstructures, the uniformity could also be increased.     

Design a backlight system to a LCD of vertical-field-switching blue phase

We propose a backlight system for a vertical-field-switching blue phase liquid crystal display. Because the blue phase liquid crystal display needs an oblique incident light source of a backlight system, we designed the backlight system that consisted of a light guide plate and a specially designed prism film. We simulated the backlight system by optical software (TraceProTM) and the performance of the blue phase liquid crystal display by liquid crystal software (TechWiz). The result showed that the contrast ratio of the blue phase liquid crystal display can be over 2000 and the uniformity was 86%. The designed applicable backlight system will be illustrated in the vertical field switching blue phase liquid crystal display.