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.

Discharge Characteristics of Micro-Needle Array Diamond Structure

CVD polycrystalline diamond surfaces were etched using reactive ion etching system with either a conventional stainless steel electrode or MgO sintered ceramic containing electrode. The micro-needle array of high aspect on diamond substrate surfaces obtained with MgO electrode was fabricated by using back-sputtering from MgO electrode. The RMS roughness of diamond substrate surfaces obtained with MgO electrode is higher than those obtained with stainless steel electrode. The secondary electron emission coefficient in Ne gas of the diamond obtained with MgO electrode was twice that obtained with the stainless steel electrode.

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.

两种LED背光驱动方案的分析与对比

LED背光驱动技术日趋成熟,背光驱动方案也越来越多,但主流方案仍是电感升压式DC/DC升压变换外加恒流控制电路。本文通过对主流解决方案中的两种方案进行分析和对比,找到了最佳的选择结果。

“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)。

[(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.

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.

Enhanced luminescence performances of Mn^(4+)-activated Sr_(4)Al_(14)O_(25)red phosphors by doping with Sc^(3+)ions

A series of non-rare earth Mn^(4+)-activated strontium aluminate phosphors Sr_(4)Al_(14)O_(25):Mn^(4+)co-doped with Sc^(3+)ions were successfully synthesized by a high-temperature solid-state reaction method.XRD result reveals that there is no introduction of additional phase but expansion of lattice with incorporation of Sc34 ions.Excitation and emission spectrum measurement shows that the synthesized phosphors can be efficiently excited by near-ultraviolet and blue light,and a deep red emission centered at 652 nm with a narrow full width at half maximum(FWHM)can be obtained,which is attributed to the transition^(2)E→^(4)A_(2)of Mn^(4+)ions.In addition,the crystal field strength parameter(Dq)and Racah parameters(B,C)and energies of states were calculated based on experimental data.Moreover,the luminous intensity of Sr_(4)Al_(14-x)SCxO_(25):Mn^(4+)is enhanced and increased by 60%compared with Mn^(4+)single incorporated sample at x=0.06.A phenomenon of redshift is observed in the excitation spectrum and discussed systematically.Finally,the mechanism of the positive effects with Sc^(3+)ions incorporated into lattice is discussed in detail.All the results suggest that the Sr_(4)Al_(13.94)Sc_(0.06)O_(25):Mn^(4+)phosphor will become one of the great candidates for backlight of LCD.

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.

First radiative shock experiments on the SG-II laser

We report on the design and first results from experiments looking at the formation of radiative shocks on the ShenguangII(SG-II)laser at the Shanghai Institute of Optics and Fine Mechanics in China.Laser-heating of a two-layer CH/CH–Br foil drives a∼40 km/s shock inside a gas cell filled with argon at an initial pressure of 1 bar.The use of gas-cell targets with large(several millimetres)lateral and axial extent allows the shock to propagate freely without any wall interactions,and permits a large field of view to image single and colliding counter-propagating shocks with time-resolved,pointprojection X-ray backlighting(∼20µm source size,4.3 keV photon energy).Single shocks were imaged up to 100 ns after the onset of the laser drive,allowing to probe the growth of spatial nonuniformities in the shock apex.These results are compared with experiments looking at counter-propagating shocks,showing a symmetric drive that leads to a collision and stagnation from∼40 ns onward.We present a preliminary comparison with numerical simulations with the radiation hydrodynamics code ARWEN,which provides expected plasma parameters for the design of future experiments in this facility.

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.

Autostereoscopic display with bicylindrical lens based on temporal-spatial multiplexing

An autostereoscopic display system with a bicylindrical lens based on temporal-spatial multiplexing technique is introduced in this paper.The system comprises a directional scanning backlight,a liquid crystal display panel with high refreshing rate,and an eye tracking device.The directional scanning backlight consists of an LED board,two lenticular lens arrays with matching periods,a parallax barrier film,and other optical films.One of the lenticular lenses is a bicylindrical lens designed to reduce aberration,hence achieving better image quality.A prototype is set up based on the proposed structure.A series of experiments are conducted,and the overall performance of the prototype is evaluated.The LEDs are divided into 10 groups that form 10 view zones.On the one hand,it achieves full resolution in both 2D and 3D display modes.On the other hand,the viewing angle is increased to t26 deg.Most importantly,the crosstalk is low.The minimum crosstalk is 6%,and the maximum crosstalk is 8.8%at a viewing angle of ±22 deg.

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.