环氧基聚合物分散液晶膜的制备及其性能研究

采用聚合相分离方法制备环氧树脂基PDLC膜.通过对液晶含量、固化温度和时间等条件进行优化,研究上述条件对PDLC膜性能的影响;使用UV-Vis、AFM、SEM等方法对聚合物的物理特性和PDLC膜的光电性质做了深入探讨.PDLC膜在传感器、光电开关、光栅以及新型分析仪器元器件等方面具有广阔的应用前景.     

A novel polarizer‐free dye‐doped polymer‐dispersed liquid crystal for reflective TFT displays

Abstract— A novel preparation method for dichroic dye‐doped polymer‐dispersed liquid crystals has been developed. This was achieved by creating a porous polymer matrix first by washing out the liquid crystal from a polymer‐dispersed liquid crystal (PDLC), which is then refilled with dye‐doped liquid crystal. Optimizing the liquid crystal used in the refilling results in decreased turn‐on voltage and faster response time. Poster‐standard reflectivity and newspaper‐standard contrast was demonstrated with a 3.8‐in. QVGA reflective TFT display with a drive voltage of 10 V.     

Nanoparticle‐embedded polymer‐dispersed liquid crystal for paper‐like displays

Abstract— A polymer‐dispersed liquid‐crystal (PDLC) matrix template embedded with nano/microparticles can be backfilled/infiltrated with a dye‐doped liquid crystal for a paper‐like reflective display. In this way, a desirable degree of diffusion can be realized to reduce the viewing‐angle dependency of a gain reflector and metallic glare without changing other electro‐optical properties.     

Viewing‐angle enhancement in holographic reflective displays by nanoscale holographic patterning

Abstract— This work presents a method to increase the viewing angle of holographic polymer‐dispersed liquid‐crystal (H‐PDLC) reflective displays. One of the drawbacks to H‐PDLC technology is the existence of a narrow viewing angle. We present a way to alleviate this problem by structuring the phase front of the recording beams to increase the viewing cone of the display. Analysis of the diffractive properties of these holograms shows that the macroscopic and the nanoscale morphologies both play a role in the optical properties of the films.     

Super‐reflective color LCD with PDLC technology

Abstract— A novel reflective color LCD without polarizers has been developed using a PDLC film and a retro‐reflector. Bright color images including moving images are achievable with ambient light. This novel LCD will enable the new application area of electronic paper.     

Mitigation of image blurring for performance enhancement in transparent displays based on polymer-dispersed liquid crystal

In this paper, we propose an effective real-time image enhancing technology for transparent displays based on polymer-dispersed liquid crystal (PDLC). The image enhancing technology consists of both global and local enhancement functions. It not only removes the affected haze but also sharpens the edge regions for transparent PDLC displays. This technology can improve the image quality such as contrast, brightness, color saturation, and gamma correction for transparent PDLC displays. The experimental results indicated that our proposed method can effectively enhance the visibility and remove the affected haze in the transparent PDLC display.     

Patterned liquid‐crystal laser film for multi‐dimensional multi‐color emissive film technology

Abstract— A two‐dimensional array consisting of dye‐doped reflection‐mode holographic‐polymer‐dispersed liquid crystal (H‐PDLC) lasers with alternating pitch lengths is presented. These post structures each reflect at a narrow bandwidth of light. The addition of laser dye to the H‐PDLC system allows for the generation of laser emission at the edge of the reflection band, or photonic band gap. In patterning these H‐PDLC post structures, a narrow‐linewidth patterned emissive color film is realized. The potential of such films and their implication in the display industry is discussed. In creating a three‐color array, an active emissive color film could replace the backlight and color filter components within the display. Such a patterned system would possess a wide color gamut, through spatial color synthesis, formed by narrow‐linewidth lasing structures with well‐defined wavelengths of emission.     

Refractive‐index matching between liquid crystals and photopolymers

Abstract— Refractive indices of two photocurable polymers, NOA65 and NOA81 (Norland Optical Adhesive), and two series of Merck liquid crystals, E‐series (E44, E48, and E7) and BL‐series (BL038, BL003 and BL006), and two UCF high‐birefringence liquid‐crystal mixtures were measured using an Abbe refractometer in the visible spectral region and 15–55°C temperature range. Some liquid crystals have excellent index matching with NOA65 in the red, while some fit better in the blue spectral region. To validate this index‐matching property found in the material level, we prepared some polymer‐dispersed liquid‐crystal devices. Good correlations between material and device performances are obtained.     

Switchable transmissive and reflective liquid‐crystal display using a multi‐domain vertical alignment

Abstract— A wide‐view transflective liquid‐crystal display (LCD) capable of switching between transmissive and reflective modes in response to different ambient‐light conditions is proposed. This transflective LCD adopts a single‐cell‐gap multi‐domain vertical‐alignment (MVA) cell that exhibits high contrast ratio, wide‐viewing angle, and good light transmittance (T) and reflectance (R). Under proper cell optimization, a good match between the VT and VR curves can also be obtained for single‐gamma‐curve driving.     

A novel diffractive backlight concept for mobile displays

Abstract— Power‐efficiency demands on mobile communications device displays have become severe with the emergence of full‐video‐capable cellular phones and mobile telephony services such as third‐generation (3G) networks. The display is the main culprit for power consumption in the mobile‐phone user interface and the backlight unit (BLU) of commonly used active‐matrix liquid‐crystal displays (AMLCDs) is the main power drain in the display. One way of reducing the power dissipation of a mobile liquid‐crystal display is to efficiently distribute and outcouple the light available in the backlight unit to direct the primary wavelength bands in a spectrum‐specific fashion through the respective color subpixels. This paper describes a diffractive‐optics approach for a novel backlight unit to realize this goal. A model grating structure was fabricated and the distribution of outcoupled light was studied. The results verify that the new BLU concept based on an array of spectrum‐specific gratings is feasible.     

Improved PI neural network-based tension control for stranded wire helical springs manufacturing

During the winding process of stranded wire helical springs (SWHSs), uneven wire tension always results in high rejection rate and non-compliance service life of SWHSs. Combining the proportion integral neural network (PINN) with a simplified actuator model, this paper presents a new control scheme for the SWHS CNC machine to keep the wire tension uniform. The PINN is improved by introducing an error variance ratio, accounting for the interaction between wires, as a modifying factor in the second hidden layer. The actuator model is simplified based on the analysis of the dynamic characteristics of the actuator. The output value of the improved PINN is transferred into control voltage value by the simplified model. The tension of each wire is controlled by an improved PINN. In order to enhance the control performance, the network parameters are updated using the gradient-based back-propagation method. The validity and consistency of the improved PINN are verified by experiments. The results indicate that (1) the computation load is slight; (2) the rising time of the step response is within 1 s; (3) 89%-96% of tension deviation values of the wire 1 and wire 3 under different process parameters are within 10% of the reference tension value; (4) the standard deviation of the wire 2 with large disturbance is 8.24 N. Compared with other algorithms (incremental PI, multiple PIDNN, PI based particle swarm optimization), the control scheme based on the improved PINN has less computation load, faster response speed and better performance in the time-varying and nonlinear system with larger disturbance.     

Projection‐based head‐tracking 3‐D displays

Abstract— This paper describes the construction and operation of four 3‐D displays in which each display produces two images for each eye and thus fits into the category of projection‐based binocular stereoscopic displays. The four 3‐D displays described are pico‐projector‐based, liquid‐ crystal—on—silicon (LCOS) conventional projector‐based, 120‐Hz digital‐light‐processor (DLP) projector‐ based, and the HELIUM3D system. In the first three displays, images are produced on a direct‐view LCD whose conventional backlight is replaced with a projection illumination source that is controlled by a multi‐user head tracker; novel steering optics direct the projector output to regions referred to as exit pupils located at the viewers' eyes. In the HELIUM3D display, the image information is supplied by a horizontally scanned, fast, light valve whose output is controlled by a spatial light modulator (SLM) to direct images to the appropriate viewers' eyes. The current statu s and the multimodal potential of the HELIUM3D display are described.     

基于PDLC的可变光衰减器的研制

介绍了一种新型的低成本、小体积的的液晶可变光衰减器的设计与制作.该衰减器采用聚合物分散液晶材料,使其填充在经过耦合的带透明导电电极的两根单模光纤的间隙里,利用聚合物分散液晶在不同电场强度下引起的光的散射效应的变化,来实现对光路能量的可控连续衰减.采用体硅微细加工技术术成功地制作出了这种衰减器,并对器件进行了测试,结果表明:当传输的光波长为1550nm时,该衰减器的插入损耗为0.85dB;衰减的最大范围为0.85dB-14.21dB;驱动电压范围9V～57V.     

Birefringent light‐shaping films for mini‐LED backlights

Birefringent light‐shaping films (BLSFs) for mini‐LED backlit liquid crystal displays (LCDs) are proposed and experimentally demonstrated by passive polymer‐dispersed liquid crystal (PDLC) films. Such films show angle‐selective scattering properties, achieved by proper material engineering and good vertical alignment of liquid crystals. They only respond to angles rather than spatial locations. By directly adhering the BLSF onto a LED, the angular intensity distribution of light can be tailored from Lambertian‐like to batwing‐like. Further simulation proves that by engineering the angular distribution, a fewer number of LEDs or equivalently a shorter light‐spreading distance is required to maintain good uniformity. These BLSFs are expected to find widespread applications in emerging mini‐LED backlit LCDs and shed light on designing other light‐shaping films in the future.     

Implementation of an LED backlight for avionics displays

Abstract— The replacement of conventional light sources used to backlight displays with LEDs is very attractive in avionics. Today's LED technology provides devices suitable to implement display backlight sources but specific requirements need to be satisfied for avionics displays. This paper covers the development of an innovative LED backlight dedicated to avionics displays, realized in a new box geometry in order to generate more than 10,000 cd/m² on a 6 × 5‐in. active area using less than 28 W of power.     

Development of a phosphorescent white OLED with extremely high power efficiency and long lifetime

Abstract— A white OLED device with extremely high power efficiency and long lifetime was developed, in which blue, yellow‐green, and red phosphorescent emitters were used. The performances achieved were 64 lm/W and 10,000 hours of lifetime at an initial luminance of 1000 cd/m² by using a light outcoupling technique. The device also exhibited the good durability important for practical usage. New technologies, such as blue phosphorescent materials and a sophisticated organic layer structure, were applied to the device. Hopefully, these technologies will open the door to the practical use of OLEDs as light sources.     

Field‐induced photo‐reactive alignment technology for the vertical‐alignment liquid‐crystal mode

Abstract— An advanced vertical‐alignment liquid‐crystal (VA‐LC) technology based on field‐induced photo‐reactive alignment (FPA) as an advanced alignment mode for VA is proposed. FPA realizes uniform alignment and a faster rising response time, especially at high voltage. This technology can generate a pre‐tilt angle only by using photo‐reactive alignment material so that the tact time is shorter and the long‐term reliability is higher than that of conventional photo‐reactive processes, which require additional photo‐reactive monomers. The advanced hybrid FPA was developed by adopting both the tilted alignment with a pre‐tilt angle and conventional vertical alignment. By using an advanced hybrid structure, the response time and contrast ratio can be further improved.     

A new pixel design and a novel driving scheme for multi‐domain vertically aligned LCDs

Abstract— By using a new pixel design and a novel driving scheme that adds a bias electrode and a bias TFT to the ordinary pixel structure, a high‐contrast‐ratio and wide‐viewing‐angle LCD mode, refered to as the biased vertical‐alignment (BVA) mode, has been sucessfully developed. Compared to the published data on the PVA and MVA modes, the BVA mode has a distinct advantage of lower manufacturing cost due to the elimination of a lithographic process step that forms either ITO cuts or protrusions on the color‐filter substrates. The BVA mode requires ITO cuts on the TFT substrate similar to that for the PVA and MVA modes. The 15‐in. BVA‐mode XGA prototype exhibits a high contrast ratio of 1200:1 and high cell transmittance of 4.3%.     

A high‐aperture‐ratio and low‐crosstalk pixel structure design for in‐plane‐switching‐mode TFT‐LCDs

Abstract— The TFT‐LCD market is growing rapidly, and the replacement of CRT TV by LCD TV requires the implementation of LC modes with wide viewing angles and high brightness. The IPS mode is an excellent technology to realize wide viewing angles, but it has a low aperture ratio that has now been improved by Advanced Super‐IPS (AS‐IPS). In this paper, we propose a novel pixel structure design that not only increases the aperture ratio but also reduces the crosstalk. We have improved the current AS‐IPS aperture ratio by 1.25 times and effectively reduced the capacitive coupling ratio from 1.2% to 0.05%.     

Design and implementation of a wavelet‐based addressing technique (WAT)

Abstract— The design and implementation of a wavelet‐based addressing technique capable of displaying gray shades is presented. The hardware complexity of the display drivers has been reduced by adding a few analog multiplexers that are common to the drivers. The controller was implemented by using a low‐cost complex programmable logic device (CPLD) and it was demonstrated by displaying 16 gray shades in a liquid‐crystal display.