LCD Modes Research Articles

P‐69: Analysis of Light Transmittance of Rugged LCDs in Random‐Vibration Environment

The light may leak out of a rugged LCD when the LCD is in random vibration environment. This paper proposes a simulation method to analyze such phenomenon. The simplified simulation model of a rugged LCD is firstly established. The power spectral density could be achieved when applying a random vibration on the rugged LCD. Inverse Flourier transformation is performed to get the change of the liquid crystal thickness in time domain. Such changes are input into TechWiz application to simulate the change of the light transmittance. In addition, the effects of different LCD modes and different thicknesses of rugged glass on the change of light transmittance in random vibration environment are deeply studied. The proposed method in this paper can help improve the display quality of a rugged LCD in random vibration environment.

Reduced off-axis gamma shift of liquid crystal display by intercepting transmittance method

Generally, the brightness and color of one image on a large-area flat panel display are different when people watch a display image under different viewing angles. The gamma shift is used to evaluate the difference of electro-optical performances under different viewing angles, namely the gray-scale display distortion. In order to reduce the gamma shift under the oblique viewing angle, the intercepting transmittance method is proposed and illustrated based on the single-domain in-plane switching blue-phase liquid crystal display (IPS-BPLCD). The results show that the off-axis image distortion index (the quantitative evaluation index of gamma shift) can be reduced by ~72% if the transmittance ratio reduces from 100% to 80% for the IPS-BPLCD with a straight electrode structure. Moreover, the zigzag electrode structure is used as the reference to illustrate the merits of the proposed method. As a result, the operating voltage of the IPS-BPLCD can be reduced by >20%, and the off-axis image distortion index is reduced by ~47% compared with the zigzag electrode structure. Besides this, the effects of the proposed method on contrast ratio, operating voltage and color difference of IPS-BPLCD are investigated as well. In fact, the proposed method is also useful for other LCD modes and electro-optical devices to achieve wide and uniform viewing angles.

P‐154: Retardation Free Polarizer for IPS Display

Retardation‐Free Polarizer, polarizer with no inner protective film, provides various advantages. With its distinct structure, it enables slim design and enhancement in quality assurance for IPS LCD devices. Compared to other LCD modes, IPS mode has better fit for adapting RF Polarizer in off angle black luminance.

Design and Implementation of Arduino Microcontroller Based Automatic Lighting Control with I2C LCD Display

The project uses closed loop control system to automatically operate a lighting system. It employed Light Dependent Resistor LDR to sense the illumination level and compare the measured signal with the reference voltage realized through the usage of a potentiometer forming a potential divider. It highlights how an operational amplifier can be used as a comparator. This idea was transferred into Arduino Microcontroller. The latter is used to compare the signals using Arduino programming functions. The Arduino is multitasked using millis() to sound alarm at system switch-On or Reset. An i2C is used to interface a Liquid Crystal Display with an advantage of using two analog pins A4 and A5 instead of four or eight I/O pins for four and eight LCD modes respectively. The innovation will allow those I/O pins dedicated to other tasks plus its attendant simplicity. The usage of i2C scanner in identifying i2C programming address as 0 × 3F is explained. The step by step explanation of Arduino codes is an asset. The paper recommends among others further improvement in the display interactivity through robust programming. An alarm could also be made to sound at each switch- over. It is believed that its simplicity will encourage its mass production with its attendant socio economic benefits.

具有CRT式快速运动图像响应时间的高性能液晶显示器

In order to analyze the image blur of displays, a simple equation to correlate the motion picture response time (MPRT) with LC response time and TFT frame rate is established. Three effective approaches to reduce MPRT are:(1) fast LC response time; (2) high frame rate, and (3) appropriate backlight duty ratio. At 120 Hz frame rate, if the LC's response time is less than 2 ms, then its MPRT would be comparable to that of OLED. LC response time can be greatly improved by employing an ultra-low viscosity LC and developing fast-response LCD modes. To achieve CRT-like MPRT (less than 1.5 ms), we could increase the frame rate or decrease the duty ratio.

29.2: Distinguished Paper: Wide Viewing LCDs using Novel Microstructure Film

AbstractA microstructure film has been developed to improve drastically LCD viewing angle characteristics (grayscale inversion, color shift, contrast ratio, etc.). By simply attaching it to the surface of commercially available LCD, the LCD has realized the excellent visibility without the blur of the frontal image and the reduction of the contrast ratio under bright ambient light conditions. This technology can be applied to various LCD modes including TN and MVA modes.

ChemInform Abstract: The TV in Your Pocket: Development of Liquid‐Crystal Materials for the New Millennium

AbstractReview: 106 refs.

The TV in Your Pocket: Development of Liquid‐Crystal Materials for the New Millennium

New liquid crystals with very low viscosity, good mesophase behavior, and high reliability are necessary to achieve the breakthrough from flat computer monitors to large displays for television. Fluorine plays a decisive role not only because of the polarity it induces in organic molecules but also because of its low polarizability and weak propensity for ion solvation. In addition, subtle stereoelectronic effects in fluorine-containing liquid crystals influence material properties and allow these to be tuned to some extent to achieve the desired outcome. Some fairly sophisticated chemistry is required that is normally ruled out in the specialty chemicals industry because of cost. The television display market is now entering a phase of saturation. The broad availability of the internet has led to an ever increasing tendency for mobile products. Tablet PCs and smartphones require touch-panel functionality and low power consumption. New LCD modes with high-performance liquid crystals and additional components, such as polymerizable materials, can be used in such products.

Viscoelastic PS brush surface offering strong anchoring at low temperature and near-zero anchoring at high temperature for LC molecules

The orientation behaviour of a nematic liquid crystal (LC) was examined in a cell consisting of two substrates on which polystyrene (PS) chains were grafted with a high density of 0.43 chains nm−2. A planar orientation of the LC was obtained in this cell and a uniform LC domain was achieved on slowly cooling the LC from the isotropic state to room temperature in a magnetic field. The PS brushes exhibited temperature-variant surface properties whereby they functioned as a strong anchoring surface at ambient temperature, viscoelastic anchoring surface at higher temperatures ranging from 45°C to 85°C and near-zero anchoring surface at 110°C (near the isotropisation temperature (Ti ) of the bulk nematic). Among these temperature-variant surfaces, the zero anchoring one is useful not only for the development of new LCD modes with novel non-contact orientation capabilities but also for the formation of an ultra-low friction interface with potential applications in number of fields.

Numerical Study on Electro-Optical Characteristics of the LCD Modes: VA, CPA, and OCB

In this paper, we report our finite element method (FEM) study on the electro-optical characteristics as well as dynamic molecular behavior for the three liquid crystal modes; vertical alignment (VA), continuous pinwheel alignment (CPA), and optically compensated bend (OCB). Our numerical study revealed that the CPA mode is very promising in view of light transmittance and wide viewing angle characteristics over the VA modes and the OCB mode exhibits an excellent dynamic response behavior over the VA and CPA modes.

Viewing‐angle compensation of TN‐ and ECB‐LCD modes by using a rod‐like liquid‐crystalline polymer film

Abstract— A liquid‐crystal line retardation‐film technology by using a rod‐like liquid‐crystalline polymer (LCP) for various LCD modes have been developed. In particular, considerable improvements in viewing‐angle performance have been achieved for the twisted‐nematic (TN) and the transmissive/transflective electrically controlled birefringence (ECB) modes by using hybrid aligned nematic film (NH Film).

51.1: Invited Paper: Viewing‐Angle Compensation of TN‐ and ECB‐LCD Modes by Using a Rod‐Like Liquid Crystalline Polymer Film

AbstractWe have developed a liquid crystalline retardation film technology by using a rod‐like liquid crystalline polymer (LCP) for various LCD modes. In particular, considerable improvements in viewing angle performance have been achieved for the Twisted Nematic (TN) and the transmissive/transflective Electrically Controlled Birefringence (ECB) modes by using hybrid aligned nematic film ‘NH Film’.

51.3: Thin Coatable Birefringent Films and Their Application to VA and IPS Mode LCDs

AbstractCrysoptix developed a novel approach to manufacturing coatable Thin Birefringence Film (TBF™) retarders based on molecular engineering of organic transparent materials. The advanced approach allows adjusting chemical structure of low molecular weight components with printing deposition techniques (including roll‐to‐roll slot die) to produce the coatable sub‐micron Thin Birefringent Films (TBF™) with the required three‐dimensional refractive index and retardation. We designed a variety of TBF™ with negative A‐plate, negative C‐plate, and biaxial retardation functions. We have developed new designs of VA and IPS LCD modes based on experimental value of refractive indices for negative C‐type and biaxial TBF™ retarders. Numerical simulation and device prototype testing have shown that application of the TBF™ retarders provides efficient optical compensation of LCD working in both VA and IPS modes.

Development of Liquid Crystalline Polymer Film “Nisseki LC Film” for Viewing Angle Compensation of Various LCD Modes

To improve quality of images of LCDs such as their viewing angle performance and coloration, liquid crystalline retardation film technology has been developed by using rod-like liquid crystalline polymer. The resulting liquid crystalline retardation film has several advantages over conventional uni- or biaxial stretched retardation film. By using liquid crystalline polymer, the direction of the principal axis can be determined freely for roll-to-roll lamination. Optical well-controlled structures such as twisted nematic, hybrid nematic and homeotropic structures can be stabilized for ideal compensation of various LCD modes including STN, TN, ECB, VA and IPS LCDs.

21.3: Compensation of Various LCD Modes by Positive O-Plates

Crossed A-plates are known to exhibit properties similar to a negative C-plate. Extending this concept, we examined compensation schemes for Twisted Nematic (TN), Optically Compensated Birefringence (OCB), and Vertically Aligned (VA) modes. By adjusting the tilt angle profile and the phase retardation, considerable improvements in contrast ratio over a wide viewing angle have been achieved for these modes.

P-155: A Novel Liquid Crystal Display Device Applicable to Memory and Dynamic Modes with a Single Panel

The monostable and bistable LCD modes have separately been researched and developed until now. We propose a novel liquid crystal display device that can be operated as memory mode as well as dynamic mode, namely dual mode. The feature of this dual mode exhibits switching among the splay, π twist, and bend states. We demonstrate switching characteristics of the novel LCD. This novel LCD device has not only a long term memory time as memory mode but also a fast response time as dynamic mode.

P-121: Equivalent Circuit Analysis of TN - LCDs Doped with Metal Nanoparticles for Fast Response

TN - LCDs doped with metal nanoparticles such as Pd, Ag, or Ag/Pd, which are protected with ligand molecules such as nematic liquid crystal, exhibit a frequency modulation EO response with short response times of ms or sub-ms order. These devices are called FM-TN-LCDs. This approach is applicable to all the existing LCD modes. These phenomena are attributed to the Maxwell-Wagner effect of heterogeneous dielectrics. It is shown that the frequency range of the FM-LCD effect is almost centered by the dielectric relaxation frequency. We formulated an equivalent circuit theory and succeeded in explaining the dependence of the dielectric relaxation time and the dielectric strength on the concentration of the nanoparticles.

32.3: Novel Optical Compensation Method Based upon a Discotic Optical Compensation Film for Wide‐Viewing‐Angle LCDs

AbstractA novel optical compensation method is proposed utilizing an optical compensation film made of a discotic compound. By precisely controlling the alignment structure of the discotic film, we have succeeded in obtaining excellent viewing angle characteristics. This idea of optical compensation is universal and applicable to any other LCD modes.

48.3: A Liquid Crystal Display Response Time Compensation Feature Integrated into an LCD Panel Timing Controller

AbstractThe electro‐optic response times of the principal LCD modes are not fast enough for video applications. Applying a one‐frame acceleration voltage, in lieu of the correct video command, can compensate the slow response time. This paper discusses the operation and design choices of a timing controller with an embedded LCD response time compensator (RTC).

51.2: Reducing Gray‐Level Response to One Frame: Dynamic Capacitance Compensation

AbstractA novel driving scheme, named Dynamic Capacitance Compensation (DCC), for active‐matrix (AM) LCDs was developed. It takes the charge‐&‐hold nature of AM‐LCDs into consideration to enhance the switching speed. By incorporating DCC and faster liquid crystal, a TFT‐LCD whose response time was less than 10 ms for all gray levels with the on + off time of 8.4 ms was developed. DCC can be applied to any kind of LCD modes to reduce the gray response time to less than 1 frame.