Stable zinc oxide field emitter-based backlight unit for liquid crystal display

A zinc oxide ZnO field emitter-based backlight unit for liquid crystal display with a gated structure is fabricated by screen-printing processes.The measured anode field emission current density reaches 0.62 mA/cm2 when the applied gate voltage is 570 V.Part of the anode current is contributed by the secondary electron emission which is excited from the MgO layer inside the gate apertures on the gate plate. The average emission current density and luminance are 0.47 mA/cm2 and 1 250 cd/m2 respectively with a fluctuation of about 10% during the 1 000 min measurement.By a finite element method calculation the gated structure shows a good electron beam focusing property. The driving performance of the backlight unit is characterized by SPICE simulation tools and measured by the oscilloscope. Stable field emission line-by-line scanning and fast response characteristics of the backlight unit indicate its promising application in the liquid crystal displays.

X-ray backlighting of two-wire Z-pinch plasma using X-pinch

Two 50-μm Mo wires in parallel used as a Z-pinch load are electrically exploded with a pulsed current rising to 275 kA in 125 ns and their explosion processes are backlighted using an X-pinch as an x-ray source. The backlighting images show clearly the processes similar to those occurring in the initial stages of a cylindrical wire-array Z-pinch, including the electric explosion of single wires characterised by the dense wire cores surrounded by a low-density coronal plasma, the expansion of the exploding wire, the sausage instability （m = 0） in the coronal plasma around each wire, the motion of the coronal plasma as well as the wire core toward the current centroid, the formation of the precursor plasma column with a twist structure something like that of higher mode instability, especially the kink instability （m = 1）.

Parameters Optimization and Energy-Saving of Highway Tunnel Backlighting with LED

In order to acquire the most energy-saving luminairedistribution-parameters(LDPs)of highway tunnel interior zone backlighting,the parameters optimization model(POM)of backlighting for tunnel interior zone was established.Yanlieshan tunnel of Jiujing highway was taken as an example for the optimization.The optimal LDPs of the backlighting system of the tunnel interior zone were obtained by the POM,a comparison between the optimization results and those of Yanlieshan tunnel’s actual lighting system was performed,which showed that the optimized backlighting system with LED lamps installed according to the optimized LDPs could save energy remarkablely even under full capacity lighting condition.Illuminance and illuminance uniformity of the tunnel road surface still met the lighting demands even the LED lamp’s luminance decreased by 30%.A backlighting simulation experiment with the optimized backlighting LDPs for Yanlieshan tunnel was accomplished in the software Dialux.The simulation results basically agreed with the optimization calculated results from the POM which proved the correctness of the backlighting POM.

Wide color gamut switchable autostereoscopic 3D display based on directional quantum-dot backlight

A switchable autostereoscopic 3-dimensional(3D) display device with wide color gamut is introduced in this paper. In conjunction with a novel directional quantum-dot(QD) backlight, the precise scanning control strategy, and the eye-tracking system, this spatial-sequential solution enables our autostereoscopic display to combine all the advantages of full resolution,wide color gamut, low crosstalk, and switchable 2D/3D. And also, we fabricated an autostereoscopic display prototype and demonstrated its performances effectively. The results indicate that our system can both break the limitation of viewing position and provide high-quality 3D images. We present two working modes in this system. In the spatial-sequential mode,the crosstalk is about 6%. In the time-multiplexed mode, the viewer should wear auxiliary and the crosstalk is about 1%,just next to that of a commercial 3D display(BENQ XL2707-B and View Sonic VX2268 WM). Additionally, our system is also completely compatible with active shutter glasses and its 3D resolution is same as its 2D resolution. Because of the excellent properties of the QD material, the color gamut can be widely extended to 77.98% according to the ITU-R recommendation BT.2020(Rec.2020).

End-on x-ray backlighting experiments for axial diagnostics of wire-array Z-pinch plasma on PPG-1

An X-pinch axial backlighting system has been designed to quantitatively measure the density distribution of wirearray Z-pinch plasmas. End-on backlighting experiments were carried out on a 200 kA, 100 ns pulsed-power generator（PPG-1） at the Tsinghua University. Compared with side-on backlighting, end-on measurements provide an axial view of the evolution of Z-pinch plasmas. Early stages of 2-, 4-, and 8-wire Z-pinch plasmas were observed via point-projection backlighting radiography with a relatively high success rate. The density distribution of Z-pinch plasma on the r–θ plane was obtained directly from the images with the help of step wedges, and the inward radial velocity was calculated. The ablation rates obtained by X-pinch backlighting experiments are compared in detail with those calculated by the rocket model and the results show consistency.

Design of 25-inch Direct Illumination-type LED Backlight

We utilized "direct illumination-type" LED backlight project, made white-light LED array in rectangle, designed a sheet of reflective film, a sheet of diffuser and two sheets of brightness enhancement film, then analyzed illuminance chart which was the result of simulation in several distance between reflective film and optical film. It showed the best matching between illuminance and uniformity while in 25mm distance. Finally, we discussed some problems with thermal dispersion.

Optical Microstructure Design Optimization for Display Backlighting

This study proposes an innovative design method for functional optical film microstructures used in displays and applies this design to LCD backlighting to replace multi-layer optical film functional integration with composite optical film. We design a novel optical film microstructure based on light uniformity and wide-angle lumination distribution and determine the optimal optical microstructure parameters by combining the global optimization of a genetic algorithm with ray tracing. The purpose of this study is to develop substitutes for traditional multi-layer prism brightness enhancers and light-diffusing film stacks and to examine the structural changes during calculations and summarize the characteristics. In this study, we focus on determining the optimal light uniformity of new optical film microstructures. The seven-inch LED backlight module of the method proposed in this study achieved 94.59% uniformity and 168° lumination distribution while reducing thickness by 66% to 82% compared to a traditional multi-layer optical film stack.

“逆境”之中显身手——巧用Backlight

在我们使用家用摄像机拍摄影像的时候可能通常使用的是程序自动曝光模式。这样可以免去调整焦距和调整光圈的麻烦,在很多的情形下,程序自动曝光模式工作得很好,我们拍出的影片令自己非常满意。但你是否遇到过这样的情况:拍摄的对象处于很亮的背景前面,或者被摄物前面部照明严重不足,也就是通常所说的逆光拍摄。这时,使用自动模式拍出来的效果就不尽人意了。画面背景显得比较亮,但却不会过度曝光,相映之下,被拍摄的主体则显得很暗,前面部细节无法很好的体现出来。这时,我们就要用到大多数家用摄像机都提供的一项功能:逆光拍摄(BackLight)。

Green and red phosphor for LED backlight in wide color gamut LCD

Wide color gamut(WCG) backlight for liquid crystal display(LCD) utilizing white light-emitting diodes(LED) has attracted considerable attention for their high efficiency and color reduction.In this review,recent developments in crystal structure,luminescence and applications of phosphors for wide color gamut LED backlight are introduced.As novel red phosphors,Mn4+activate fluoride and aluminate phosphors are advanced in quantum efficiency,thermal quenching and color saturation for their characteristic spectrum with broad excitation band and linear emission.The crystal structure and fluorescence properties of Mn4+doped fluosilicate,fluorogermanate,fluotitanate,as well as Sr4 Al14O25,CaAl12O19 and BaMgAl10O17 phosphors are discussed in detail.A serial of narrow-band red-emitting Eu2+,Eu3+and Pr3+-doped nitride silicates and molybdate phosphors are also introduced.Rare-earth-doped oxynitride and silicate green-emitting phosphors have attracted more and more attention because of the wide excitation,narrow emission,high quenching temperature,high quantum efficiency,such as β-sialon:Eu2+,Ba3Si6O12N2:Eu2+,MSi2O2N2:Eu2+(M=Ca,Sr,Ba),y-AlON:Mn2+and Ca3Sc2Si3O12:Ce3+.All above phosphors demonstrate their adaptability in wide color gamut LCD display.Especially for Mn4+doped fluosilicate red phosphor and β-sialon:Eu2+green phosphor.To achieve an ultra-high color gamut in white LED backlight and against the OLED,innovative narrow-band-emission red and green phosphor materials with independent intellectual property rights are continuously pursed.

Micro-projection dynamic backlight for multi-view 3D display

A micro-projection dynamic backlight for multi-view three-dimensional(3D)display is proposed.The proposed backlight includes a light emitting diodes(LEDs)array,a lenticular lens array,and a scattering film.The LED array,the lenticular lens,and the scattering film construct a micro-projection structure.In this structure,the LEDs in the array are divided into several groups.The light from each LED group can be projected to the scattering film by the lenticular lens and forms a series of bright stripes.The different LED groups have different horizontal positions,so these bright stripes corresponding to different LED groups also have different horizontal positions.Therefore,they can be used as a dynamic backlight.Because the distance between the LEDs array and the lenticular lens is much larger than the distance between the lenticular lens and the scattering films,the imaging progress will make the width of the bright stripes much smaller than that of the LEDs,and the pitch of the stripes is also decreased.According to the 3D display theory,the bright stripes with small width and pitch help to increase the number of views.Therefore,the proposed micro-projection dynamic backlight is very suitable for multi-view 3D display.An experimental prototype was developed,and the experimental results show that the micro-projection dynamic backlight can correctly complete the directional projection of the parallax images to form a 3D display.

ZnO induced self-crystallization of CsPb(Br/I)_(3) nanocrystal glasses with improved stability for backlight display application

In the current situation of energy shortages,saving energy and reducing consumption are undoubtedly valid methods to relieve the pressure on resources.CsPbX_(3)(X=Cl,Br,and I)perovskites as star inorganic materials have drawn growing attention owing to their unique properties,making them suitable for applications such as light-emitting diodes(LEDs),solar cells,photodetectors,or lasers.This work presents zinc oxide(ZnO)induced self-crystallized CsPb(Br/I)_(3) perovskite with a 26%photoluminescence quantum yield(PLQY)prepared by the traditional melt-quenching method.Furthermore,the full width at half maximum(FWHM)(34–44 nm)can be regulated by the ZnO content.In addition,as a downconverter,CsPb(Br/I)_(3) perovskite nanocrystals(NCs)realize a bright red backlight that covers≈94%Rec.2020 standards in the CIE 1931 color space and 126%of National Television System Committee(NTSC).This finding undoubtedly confirms an effective path for fabricating perovskite materials in a green,low-cost,and time-saving way,enriching the knowledge of glass crystallization mechanisms and promoting their applications in wide color gamut backlights.

Real-time pupil tracking backlight system for holographic 3D display(Invited Paper)

We propose an automatic three-dimensionM （3D） pupil tracking backlight system for holographic 3D display system with large image size and full-parallax accommodation effect. The proposed tracking module is applied to a holographic 3D display system with two sets of directional holographic imaging module composed of 2 × 2 large scale lens array and 22-inch high-resolution liquid crystal display 3D panel. System architecture is described and experimental results are presented.

[(CH_(3))_(4)N]_(2)Mn_(0.6)Zn_(0.4)Br_(4):Lead-free MnII-based hybrid halide with high photoluminescence quantum yield for backlight displays

High efficient lead halide perovskites with wide-color gamut properties have emerged as new candidates for backlight displays.However,the toxicity of lead and the instability of halide perovskites greatly limit their practical applications.Herein,the luminescent powders of[(CH_(3))4N]2MnBr_(4)and[(CH_(3))4N]MnBr3 were synthesized via a simple yet robust solvent evaporation method.[(CH_(3))4N]2MnBr_(4)with tetrahedral coordination Mn^(2+)and[(CH_(3))4N]MnBr3 with octahedral coordination Mn^(2+)show green at 517 nm and red emission peaks at 620 nm,respectively,originating from the^(4)T1-^(6)A_(1)transition of Mn^(2+).To enhance optical of manganese halide via effective alloying,Zn^(2+)-doped[(CH_(3))4N]2MnBr_(4)was successfully prepared,and the quantum efficiency of[(CH_(3))_(4)N]_(2)Mn_(0.6)Zn_(0.4)Br_(4)was as high as 65%.Furthermore,[(CH_(3))4N]2Mn0.6Zn0.4Br_(4)exhibits better optical and thermal stability compared to[(CH_(3))4N]2MnBr_(4).[(CH_(3))_(4)N]_(2)Mn_(0.6)Zn_(0.4)Br_(4)@CsPbBr_(1.2)I_(1.8)light conversion films with different green-to-red ratios are placed in backlight display devices,and their color gamut exceeds 106%of the National Television Standards Committee(NTSC)1953 standard,which is superior to the currently reported Mn-based perovskite.This work broadly shows that the[(CH_(3))_(4)N]_(2)Mn_(0.6)Zn_(0.4)Br_(4)will provide effective route to fabricate stable and high-performance lead-free liquid crystal displays.

液晶汽车仪表LED背光硬件电路分析与设计

为了使液晶汽车仪表的背光灯在受到外界电气干扰的情况下能够保持稳定的输出电流、亮度不发生变化,对已使用的三种汽车仪表LED背光电路进行了研究和分析,提出了一种稳定性较高的硬件电路设计——仪表LED恒流源电路。该电路可通过调节精密电阻值来调节LED背光灯的亮度,设计方案简单、调整电流便捷、成本较低,在液晶汽车仪表市场中具有较高的应用价值。

基于前背景特性的逆光交通场景图像增强

由于逆光交通场景下采集到的图像存在前景亮度过低、背景亮度失真等特点,导致采集图像清晰度低、信息丢失严重和可识别性差,针对逆光图像前背景的不同特性,研究提出了一种分区域增强方法。对逆光图像使用最大类间方差法(OTSU法)分割图像的前景和背景;对逆光图像全局使用LIME方法,提升前景亮度的同时保持色彩的失真度;单独将背景部分RGB三个通道上的全局直方图均衡化结果一一映射到对应的限定区间内,提高了背景的对比度;使用Canny算子检测出前背景拼接处的黑边,根据黑边生成3个自适应的滤波模板对黑边进行分步均值滤波处理,消除了黑色边缘,提升了图像的视觉质量。在实验室自建的CHD_B数据集上,所提方法在4种常用客观评价指标上综合占优。实验结果表明,所提出的图像增强算法能有效地消除图像中的逆光现象。

基于区域调光算法的车载液晶显示技术研究及应用

为了提升传统车载液晶显示器的能效和显示质量,提出一种应用于车载液晶显示器的区域调光算法。将输入的RGB色彩模式转换为YUV色彩模式以提取像素点亮度数据,并依照背光分区对应的图像子区域提取亮度数据。采用分区背光模糊-扩散模拟LED背光源在背光模组中传播时的扩散过程,得到各像素点的背光亮度数据,并据此通过液晶像素进行精确补偿得到最终调光图像。仿真结果显示,该方法在图像信息熵、图像细节增强和峰值信噪比3个评价方法上,优于其他区域调光算法的增强效果。同时在样机实验中,平均整体能耗降低了20.7%。表明该算法能够在提高显示质量的同时合理降低车载显示器的整机功耗,对各类车载显示器都具有良好的适用性。

改进残差网络下体操动作逆光图像超分辨增强

超分辨图像有利于信息获取与传递,但当下缺少对逆光低分辨率图像的研究。为解决逆光图像中阴影噪声的问题,提出一种基于改进Retinex逆光图像分解增光算法,通过结合DRAN双重残差注意力网络,构建出逆光图像超分辨率增强模型,即NRE-DRAN模型。模型首先将基于Retinex理论将逆光图像分解成光照量图与反射量图,并通过调节网络与恢复网络处理两分量图,然后将处理后的分量图融合,降低逆光噪声的影响;接着采用DRAN特征提取模块提取浅层纹理特征与深层语义特征,然后利用信息蒸馏模块增强特征信息,并串联拼接成融合特征图,最后基于残差图与上采样图重构出超分辨图像。多组基线算法叠加模型仿真对比结果表明,在GBI体操动作逆光图像数据集上,NRE-DRAN模型具有最优的SSIM指标(较其它叠加模型相比平均提升了3.93%)与较优的PSNR指标(指标排名第二)。综上所示,NRE-DRAN逆光图像超分辨率增强模型在解决逆光阴影噪声问题的同时有效的增强了图像的超分辨率,且该模型具有较高的时效性。

强激光加载下铝、锡微喷特性实验研究

基于皮秒激光驱动的高能X射线源具有微焦点、高亮度和高分辨的优良特性,已成为研究金属材料微层裂和微喷射现象的热门诊断方法之一。锡因其熔点较低而成为微喷研究熔化影响的首选材料,铝由于熔点相对较高,不易发生冲击或卸载熔化形成液滴喷射,因此,铝微喷实验研究结果相对较少。基于“星光-III”激光装置的纳秒加载源和皮秒束诊断源,发展了皮秒激光驱动高能X射线背光照相技术,研究了表面含V型几何缺陷的金属锡、铝微喷特性,通过延时控制,获取了两种典型金属微喷射过程的高分辨物理图像,得到了喷射物质的形态分布、平均速度和面密度分布等重要信息。采用SPH方法对实验结果进行了数值模拟分析,揭示了实验中喷射物的形成机理以及高速喷射物质的来源。

氧化镧对Mini LED背光基板玻璃热学性能的影响

通过在Mini LED背光基板玻璃的基础组成中引入氧化镧(La_(2)O_(3)),探究La_(2)O_(3)/Na_(2)O、La_(2)O_(3)/CaO及La_(2)O_(3)/B_(2)O_(3)对基板玻璃热膨胀系数和导热系数的影响。结果表明,随着La_(2)O_(3)/Na_(2)O组分比的增加,玻璃的热膨胀系数和导热系数均呈下降趋势;随着La_(2)O_(3)/CaO组分比的增加,玻璃的热膨胀系数在(9.3~9.5)×10^(-6)/℃区间波动,导热系数呈下降趋势;随着La_(2)O_(3)/B_(2)O_(3)组分比的增加,玻璃的热膨胀系数降低,导热系数呈升高趋势。

改进MSRCR的透明物体逆光图像增强算法

针对透明物体逆光图像对比度低、可视质量差、部分区域过度曝光、边缘信息模糊等问题,提出了一种改进MSRCR(Multi-Scale Retinex with Color Restoration)的透明物体逆光图像增强算法。首先,在MSRCR算法的基础上添加最小可觉差的倒数作为光照分量的调节因子,解决图像的色偏问题,得到准确清晰的透明物体边缘信息;然后,利用自适应对比度增强算法对原图像进行处理,得到亮度适中,对比度高的图像;最后,将两幅图像按亮度均值比例进行拉普拉斯金字塔融合,并进行线性拉伸。将该算法应用于安瓿瓶视觉尺寸测量,结果表明:改进MSRCR的透明物体逆光图像增强算法,能有效解决MSRCR算法的色偏问题,突显透明物体边缘细节信息,并保留亮度增强效果,将安瓿瓶的尺寸误差由0.35 mm降低到0.1mm,提高了透明物体尺寸测量精度。