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.

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.

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.

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.

Liquid Crystal Motion Picture Projector

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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.

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.

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.

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）.

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 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.

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.

Electrically controlled optical choppers based on holographic polymer dispersed liquid crystal gratings

An electrically controlled optical chopper based on switchable holographic polymer dispersed liquid crystal （H-PDLC） gratings is demonstrated through a programmable, adjustable, and periodic external driving source. Compared with traditional mechanical optical choppers, the H-PDLC chopper exhibits many advantages, including faster response time, less waveform deformation, as well as easier integration, control, and fabrication, to name a few. Its excellent performance makes the device potentially useful in frequency modulation optical systems, such as frequency division multiplexed microscopy system.

Design of a titl angle measurement system based on ADXL345 sensor

The titl angle measurement system based on the ADXL345 of three-axis acceleration sensor is introduced, and the composition and working principle of the system are described. The MSP430F149 microcontroller of ultra-low power and high performance is adopted. Firstly, the voltage value which is proportional to the acceleration value is output by ADXL345 when the system is powered. Secondly, the voltage value is converted into the corresponding digital signal by AD converter of the sensor. Thirdly, the digital signal is transformed into the titl angle according to the arithmetic processing of the MSP430F149. Finally, the corresponding angle is displayed on the liquid crystal display （LCD） screen. Experimental results show that the design has high sensitivity and response speed compared with the conventional methods. It is suitable for practical engineering application because of simple structure, low cost and low power consumption.

Study on the Multi-Sensing System Based on the Tin Oxide pH Electrode

In this study,the multi-sensing system based on the tin oxide pH electrode for the ion-determination was presented. With the advantages of the real-time supervisory control apparatus,the measured values could be displayed on the liquid crystal display (LCD) immediately.In this study,the basic sensor was the tin oxide pH electrode,which was fabricated by radio frequency (r.f.) sputtering system on the indium tin oxide (ITO)/glass substrate.Moreover,the major blocks of the system consist of the tin oxide electrode-based ion selective electrodes (ISEs),an analog front-ended readout circuit,a microcontroller with built-in analog to digital (A/D) converter.In addition,by the embedded system design,the measurement results can be transmitted to a portable system or computer through the Universal Serial Bus (USB) and Universal Asynchronous Receiver Transmitter (UART) interface immediately.According to the experimental results,the multi-sensing system has high performance and reliability for pH,K^+,and Na^+ detection.

Phase-only Correlation Measurement with Computer-controlled LCD and CCD Image Processing System

Using computer-controlled liquid crystal display (LCD) as an image processor and a CCD camera as a detector, phase-only correlation measurement is performed with the aid of joint transform correlation method (JTC). This computer -controlled LCD-CCD image processing system may be a powerful tool for defect detection, position control and pattern recognition. It enables new possibilities in analog real-time image processing. This is of great interest in microelectronic manufacturing today and in the future.