Optical simulation of in-plane-switching blue phase liquid crystal display using the finite-difference time-domain method

The finite-difference time-domain method is used to simulate the optical characteristics of an in-plane switching blue phase liquid crystal display.Compared with the matrix optic methods and the refractive method,the finite-difference timedomain method,which is used to directly solve Maxwell＇s equations,can consider the lateral variation of the refractive index and obtain an accurate convergence effect.The simulation results show that e-rays and o-rays bend in different directions when the in-plane switching blue phase liquid crystal display is driven by the operating voltage.The finitedifference time-domain method should be used when the distribution of the liquid crystal in the liquid crystal display has a large lateral change.

Novel cell parameter determination of a twisted-nematic liquid crystal display

In this paper a novel method is proposed to determine the cell parameters including the twist angle, optic retardation and rubbing direction of twisted-nematic liquid crystal displays （TNLCD） by rotating the TNLCD. It is a single-wavelength method. Because using subtraction equation of transmittance as curve fitting equation, the influence of the light from environment and the absorption by polarizer, the sample of TNLCD and analyser on the transmittance is eliminated. Accurate results can also be obtained in imperfect darkness. By large numbers of experiments, we found that not only the experimental setup is quite simple and can be easily adopted to be carried out, but also the results are accurate.

COMPENSATION EFFECT OF POLYIMIDE THIN FILMS ON NORMALLY WHITE TWISTED NEMATIC LIQUID CRYSTAL DISPLAYS

The disadvantages of Normally White Twisted Nematic Liquid Crystal Display (NW-TN-LCD) were discussed. The reason that the negative birefringent polyimide thin films were used to compensate NW-TN-LCD to decrease off-axis leakage, improve contrast ratios and enlarge viewing angles was explained in this paper. A certain polyimide thin film was taken as an example to show compensation effect on NW-TN-LCD.

NOVEL POLYMER WIDE VIEWING ANGLE COMPENSATION FILMS FOR LIQUID CRYSTAL DISPLAYS(LCDS)

We report on generating uniaxial negative birefringent compensation films, made of specifically designedpolyimides. These polymers were synthesized via a polycondensation of dianhydride [such as 2, 2' -bis(3, 4-dicarboxyphenyl)hexafluoropropane dianhydride] and 2, 2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl. The uniaxial negative birefringent (n_x =n_y > n_z) polyimide substrates are achieved using a solution-casting method in conventional solvents, which exhibit thedesirable optical phase retardation [(n_x - n_z)×d] values from 50 to 400 nm varying with the film thickness. In thesepolyimide films, the long chain rigid molecules adopt intrinsic planar orientaion. In detail, the majority of phenylene-imiderings and phenylenes preferentially adopt nearly planar conformations parallel to the film substrae. In addition, these filmsalso possess high transparency (or transmittance) and little color shift. The unique color dispersion curve indicates that thistype of materials is very suitable for the applications in LCDs due to an excellent mimic for the retardation color dispersioncurve with respect to LC molecules. Significantly low in-plane retardation (< 1 nm) allows this new technology based film toachieve sufficiently high contrast ratio while highly negative retardation dramatically suppresses the gray scale inversion toimprove the viewing angle performance in a variety of new mode LCDs.

Low voltage transflective blue-phase liquid crystal display with a non-uniform etching substrate

A transflective polymer-stabilized blue-phase liquid crystal display（BP-LCD） with a non-uniform etching substrate is proposed.In-plane switching（IPS） electrodes on the bottom substrate are put on the different gaps,and the bottom substrate between the electrodes is etched into different depths in transmissive（T） and reflective（R） regions.This structure can balance the optical phase retardation in the two regions and is helpful to achieve well-matched voltag-dependent transmittance and reflectance curves.This transflective display has high optical efficiency,a wide viewing angle,and low operating voltage（approximately 6 V）.

Development of hydrometallurgical process for indium recovery from waste liquid crystal display using Cyphos IL 101

The main goal of this study was to recover indium from the waste liquid crystal display(LCD)panel.In this context,an ionic liquid Cyphos IL 101 was explored.The extraction parameters such as equilibration period,acid concentration,chloride ion concentration,hydrogen ion concentration were examined on the extraction efficiency of Cyphos IL 101 towards In(III).Quantitative extraction of indium was found at 2.0 mol/L HCl using 0.005 mol/L Cyphos IL 101 and quantitative stripping with 1.0 mol/L H2SO4.Job’s method was used to determine the extracted species and R3R'PInCl4(R=C6H13;R′=C14H29)was proposed.Based on the observations on multi-metal studies,Cyphos IL 101 was further employed for the removal of indium,tin and copper from the leach liquors of waste LCDs.Optimized conditions were generated for the recovery of indium from waste LCDs.McCabe−Thiele diagram analysis,counter-current extraction and selective stripping were carried out to separate the metal ions,i.e.,indium,tin and copper.Two stages at O/A ratio of 1:3 were required for complete removal of tin from the feed and selective stripping of In and Sn was achieved using 0.1 mol/L H2SO4.A scheme for separating indium from the waste LCDs was proposed.

A fast-response in-plane switching liquid crystal display with a protrusion structure

The widespread use and application of in-plane switching liquid crystal displays （IPS-LCDs） is limited by their slow response. In this letter, a fast-response IPS-LCD with a protrusion structure is proposed. The gray-to-gray response time of the IPS-LCD is reduced by 20% to 30%. The difference in cell gap induced by the protrusion accounts for the faster response. Moreover, the viewing angle and ganmla shift of tile proposed IPS-LCD are simulated and found to be better than that of conventional IPS-LCDs.

Homogeneous-aligned high-transmission and fast-response liquid crystal display with three-layer electrodes

A homogeneous-aligned, high-transmission, and fast-response liquid crystal display （LCD） with three-layer electrodes is proposed. The molecules of liquid crystals are more inclined to rotate above and between the pixel electrodes. This induces a much higher transmission than that of the cell driven by the fringe field switching method and a wide viewing angle simultaneously because of the combined fringe and in-plane electric fields. Furthermore, a trigger pulse voltage is applied between the top and common electrodes to forcibly align the liquid crystal molecules vertically to show the transient dark state, which results in a very fast turn-off time （-1 ms）. With high degree of transmission and fast response time, this kind of LCD is a potential candidate for large LCD panels.

Liquid crystal display and organic light-emitting diode display: present status and future perspectives

Recently,‘Liquid crystal display(LCD)vs.organic light-emitting diode(OLED)display:who wins?’has become a topic of heated debate.In this review,we perform a systematic and comparative study of these two flat panel display technologies.First,we review recent advances in LCDs and OLEDs,including material development,device configuration and system integration.Next we analyze and compare their performances by six key display metrics:response time,contrast ratio,color gamut,lifetime,power efficiency,and panel flexibility.In this section,we focus on two key parameters:motion picture response time(MPRT)and ambient contrast ratio(ACR),which dramatically affect image quality in practical application scenarios.MPRT determines the image blur of a moving picture,and ACR governs the perceived image contrast under ambient lighting conditions.It is intriguing that LCD can achieve comparable or even slightly better MPRT and ACR than OLED,although its response time and contrast ratio are generally perceived to be much inferior to those of OLED.Finally,three future trends are highlighted,including high dynamic range,virtual reality/augmented reality and smart displays with versatile functions.

Polymer-stabilized blue phase liquid crystal display with slanted wall-shaped electrodes

A polymer-stabilized blue phase liquid crystal display （BPLCD） with slanted wall-shaped electrodes is proposed. Compared with the traditional BPLCD with wall-shaped electrodes, the electrodes of the proposed BPLCD are slightly angled to obtain phase retardation in the entire cell even at the position of electrodes. The proposed BPLCD demonstrates a relatively higher average transmittance and overall brightness than the traditional BPLCD.

Emerging Technologies of Liquid Crystal Displays

The general features and the emerging technologies of liquid crystal displays are described from the viewpoints of wide viewing and fast response technologies. The device applications of liquid crystals for optical communications are also described.

Liquid crystal Fresnel lens display

A novel see-through display with a liquid crystal lens array was proposed.A liquid crystal Fresnel lens display（LCFLD） with a holographic screen was demonstrated.The proposed display system has high efficiency,simple fabrication,and low manufacturing cost due to the absence of a polarizer and color filter.

Liquid Crystal Motion Picture Projector

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Cinnamate-functionalized hyperbranched polymer as liquid crystal photo-alignment layer

In this work, 4-methoxylcinnamoyl chloride was reacted with a commercial hyperbranched polymer （Boltom-TM H30） to prepare a hyperbranched photosensitive polymer （H30-Ci）. The polymer was characterized by UV absorption spectrum and 1H- NMR spectrum. After processed by Linearly Polarized Polymerization （LPP） method, the spin-coated films of H30-Ci were used as photo-alignment layers to assemble liquid crystal （LC） cells containing nematic liquid crystal （5CB）. The observation by polarized microscope showed that the H30-Ci blended with a linear polymer （BP-AN-Ci） photo-alignment layers could align LC molecules in a very uniform way.

Elimination of Zig-zag Defects in Surface-stabilized Ferroelectric Liquid Crystal Cells

The elimination of zig-zag defects in polyimide-coated surface-stabilized ferroelectric liquid crystal(SSFLC) cells is carried out by applying a low-frequency electric field. It has been achieved when the thickness of SSFLC cell is 3 μm. The optical spectral transmittance measurement confirmed that there is no change of layer structure, and the memory capability was not improved. The different effects of low-frequency electric field applied on the different thickness FLC cells have been observed, and experimental results were presented.

Electro-optical Properties of Liquid Crystal Composite Materials

The liquid crystal composite materials consist of microdroplets of liquid crystals which are spontaneously formed in a matrix of a polymer at the time of its polymerization. The director configuration in liquid crystal droplets, the model of orientation of droplets, and the contrast ratios of a cell are investigated. Droplet size, spacing and distribution are readily controlled in these materials to allow optimization of displays based upon electrically controlled light scattering from the liquid crystal droplets. Preliminary experimental and theoretical studies of the light scattering and electro-optic response of new material show that these materials can offer new features suitable for large area displays and light valves.

Light Emitting Diodes as a Rapid Visual Display for Use in Psychological Experiments

In this paper we show how light emitting diodes (LEDs) can be used in conjunction with existing display technologies as a means for achieving ultra-rapid visual stimulus exposure durations. We review existing rapid visual display methods, and show how our apparatus overcomes the limitations inherent with each technique. Our apparatus, the LED tachistoscope, takes advantage of the fast-switching times and high-brightness capabilities of LEDs in order to present stimuli at previously unachievable durations as rapid as 1 ms. The rapid exposure durations are achieved by external LED backlight illumination of images on a liquid crystal display (LCD) after the components of the LCD have stabilized. This ensures that stimulus onset and offset are discrete. Furthermore, the fast-switching of the LEDs enables stimuli to be revealed for very rapid durations. The paper also describes studies in which the LED tachistoscope has already been applied, and offers suggestions for other possible applications. Interestingly, in our studies we show that the human visual system is very adept at extracting information with only very minimal stimulus exposure durations. Such studies have not been possible with existing display equipment. The LED tachistoscope opens up avenues for a variety of psychological and physiological experiments and provides a means for revealing the limits of human visual perception.

Double sided roll-to-roll manufacture of flexible display panels

A double sided roll-to-roll(R2R) system has been developed by the authors to automate the continuous manufacturing of flexible display panels.Here we report an overview of the system operation and the fabrication process.The system framework features a timer initiated slot-die coating followed by wet lamination to form a thin,active layer in between flexible conductive substrates.A rotary screen-printing unit is installed for adhesive deposition providing an edge seal for the panel.The system enables production of 15-cm^2 laminated panels.

Flat-Panel Laser Displays Based on Liquid Crystal Microlaser Arrays

Laser displays,benefiting from the characteristic merits of lasers,have led to the revolution of next-generation display technologies owing to their superior color expression.However,the acquisition of pixelated laser arrays as self-emissive panels for flat-panel laser displays remains challenging.Liquid crystal(LC)materials with excellent processability and optoelectronic properties offer considerable potential for the construction of highly ordered multicolor laser arrays.Here,we demonstrate flat-panel laser displays on LC microlaser pixel arrays through a microtemplate-assisted inkjet printing method.Individual organic red-green-blue(RGB)microlaser pixel arrays were obtained by doping dyes into LCs with photonic band edges to obtain single-mode RGB lasing,leading to a much broader color gamut,compared with the standard RGB color space.Then we acquired periodically patterned RGB pixel matrices by positioning LC microlasers precisely into highly ordered arrays,according to the well-organized geometry of the microtemplates.Subsequently,we demonstrated full-color flat-panel laser displays using the LC microlaser pixel matrices as self-emissive panels.These results provide valuable enlightenment for the construction of next-generation flat-panel laser display devices.

Triboelectric-optical responsive cholesteric liquid crystals for self-powered smart window,E-paper display and optical switch

Intelligent responsive devices are crucial for a variety of applications ranging from smart electronics to robotics.Electro-responsive cholesteric liquid crystals(CLC)have been widely applied in display panels,smart windows,and so on.In this work,we realize the mechanical stimuli-triggered optical responses of the CLC by integrating it with a triboelectric nanogenerator(TENG),which converts the mechanical motion into alternating current electricity and then tunes the different optical responses of the CLC.When the voltage applied on the CLC is relatively low(15–40 V),the TENG drives the switching between the bistable planar state and focal conic state of the CLC,which shows potential applications in selfpowered smart windows or E-paper displays.When the voltage supplied by the TENG is larger than60 V,a self-powered optical switch is demonstrated by utilizing the transformation between focal conic state and instantons homeotropic state of the CLC.This triboelectric-optical responsive device consumes no extra electric power and suggests a great potential for future smart electronics.