Reflective LCD Research Articles

49‐1: Invited Paper: Novel Brightness Enhancement Technology for Reflective LCDs

Reflective LCDs have a great advantage of low power consumption, but the brightness is not consistently sufficient because ambient light is used as a light source. To increase light efficiency, we combined reflective LCDs and the Pancharatnam‐Berry deflector (PBD), a diffractive optical element that controls the propagation of incident light. We confirmed that on‐axis brightness is increased by 2.2 times against the incident collimated light from a polar angle of 30° when compared to a reflective LCD without PBD.

52‐4: Research on the Process of Single Polarizer Reflective LCD

52‐4: Research on the Process of Single Polarizer Reflective LCD

31‐3: In‐cell touch supported novel reflective LCD mode Development

The novel display mode for in‐cell touch reflective LCDs was developed. The basic optical display performance in test cells was almost same as conventional VA. In addition, the touch performance of the prototype in‐cell touch reflective module (the simple modification of the transmissive) was equivalent to the conventional transmissive. The optimal panel design for this display mode is currently under development.

35‐2: A kind of Front Light Source Module Adapted to Reflective LCD

Reflective Liquid Crystal display (RLCD) has the advantage s of low power and lightweight relying on the metal layer in TFT glass to reflect the environment light, developing rapidly in the outdoor display, e‐books, price tag, and sports watch market. However, when the ambient light weaker, RLCD requires an additional light source. Therefore the development of the front light source has become a new research direction. This paper designed a thin front light source adapted to Reflective LCD by using the microstructure to control light angle. Optimize microstructure parameters to improve contrast ratio and light efficiency utilization. The density arrangement of microstructures to achieve the higher uniformity and no moire.

87‐1: Invited Paper: A Novel Reflective 90‐inch TFT LCD with UV2 A Technology

We have developed a large size reflective LCD providing good visibility under bright circumstances and high productivity. To obtain wide viewing angle reflective mode, the panel design for the 2‐domain aligned LCD with UV2 A technology was examined. We adopted it into a prototype and successfully fabricated a 90‐inch TFT LCD.

47‐3: Invited Paper: Development of Reflective LCDs with High Contrast Ratio and High Reflectivity

A kind of reflective mode LCD was reported years ago by professor Shin‐Tson Wu, called Mixed‐mode Twisted Nematic (MTX) LCD[1]. Based on MTN mode RLCD, we promoted the contrast ratio and reflectivity of RLCD by optimizing the cell structure and pixel design. Meanwhile, according to controlling the different optical layer axis directions and using new type materials, the contrast ratio and reflectivity are increased further. To improve the visibility of RLCD in a dark environment, we also developed the front light unit solution.

59‐2: Brightness Improvement of Reflective LCD

Through the comparison of the measurement results and the simulation results of the reflectivity, we have found an optical simulation method which can be applied to the reflectivity simulation of reflective LCD. The design of MRS can be optimized conveniently by the simulation method, and the best MRS design parameters were obtained. The optimized design of MRS may cause the RLCD high reflectivity.

High-Performance and Low-Power Full Color Reflective LCD for New Applications

High-Performance and Low-Power Full Color Reflective LCD for New Applications

High-Performance and Low-Power Full Color Reflective LCD for New Applications

High-Performance and Low-Power Full Color Reflective LCD for New Applications

P‐106: Guest‐Host Liquid Crystal Devices Utilizing Dichroic Dye and Its Application

Wide application of dichroic dye‐doped liquid crystal device (DLCD) devices has been proposed, which removes conventional film‐type polarizer in reflective LCD and OLED. Combination of DLCD, quarter‐wave film and reflector can realize effective reflective LCD. In addition, by replacing conventional polarizer to switchable DLCD in OLED, the proper level of a low reflection is achieved, and more interestingly high brightness OLED can be realized if the optic axis of DLC is switched to vertical alignment when there is no ambient light, which could save power consumption and life time of OLED. Further DLCD can be applied to bi‐functional device functioning as both smart mirror and light shutter.

44‐2: Distinguished Paper: A Full Integration of Electromagnetic Resonance Sensor and Capacitive Touch Sensor into LCD

We have developed a transmissive and reflective LCD which integrates electromagnetic resonance and capacitive touch sensors using existing in‐cell process. This technology has a good SNR of 42.5dB for electromagnetic resonance pen sensing and contributes the added benefits for thin design, lightweight panel, compared to conventional LCD techniques.

20‐1: Fast Switching Twisted‐Vertically Aligned Mode Reflective LCD using Mortar‐shaped Pixel Structure

We have developed fast switching twisted‐vertically aligned mode reflective LCD using mortar‐shaped pixel structure. We realized axially symmetric pretilt angle in each pixel by the mortar‐shaped pixel structure fabricated by the UV pattern exposure and achieved high quality reflective LCD with high reflectivity and wide viewing angle range.

39‐1: A Low‐Power Reflective LCD Based on a‐Si:H TFT Process

Developed a 1.28inch 64‐color low‐power reflective LCD based on the a‐Si:H TFT process. This display achieves a minimum frame rate of 1 Hz and a corresponding power consumption of less than 75 uW. The maximum frame rate is 58 Hz, at which a smooth dynamic picture can be displayed. We overcome the flicker issue of low frame rate by adopting new pixel and drive design. After 240 hours of 60 ° C / 90% RH dynamic reliability testing, the flicker is still within the visually acceptable range.

20‐4: High‐Performance and Low‐Power Full Color Reflective LCD for New Applications

We have developed a reflective LCD with full color video image and low power consumption. By combining a new twisted VA‐LC mode, a silver alloy electrode with micro reflective structure (MRS), and IGZO‐TFT technology, a 22‐inch prototype has achieved excellent optical properties and flicker‐less 1Hz driving.

The fiftieth anniversary of the liquid crystal display

ABSTRACTA record is given of the special meeting organised by the UK&I Chapter of the Society of Information Display held at the Royal Academy of Engineering in London, to celebrate the 50th anniversary of the RCA announcement of the first Liquid Crystal Display on 28th May 1968. Coming exactly eighty years after the report of the first liquid crystal materials, this announcement sparked interest across the globe, and particularly in the UK, Switzerland and Japan. Presentations of the early LCD history from Hilsum, Schadt and Raynes give insights into both the science and also the process of invention itself. These early contributors are followed by a view from the USA from Bos and representation from the companies Sharp and Merck that helped shape the success of these fascinating and useful materials. Also reviewed are talks on the use of organic semiconductors to drive plastic LCD by Sirringhaus, reflective LCD of Folium Optics, retail signage of Displaydata, as well as a look to the future from LCD competitors from Bodle (Phase Change Material displays) and BOE (OLED).

49‐4: A Low‐power Reflective LCD System with Adaptive Compression Algorithm of Grey Scale

A 1.28‐inch 6‐bit color low‐power reflective LCD prototype has been developed by using low refresh rate system and memory‐type pixel (MTP) structure. As there is an intrinsic problem for the MTP structure that large flat areas, and loss of detail become noticeable when original 8‐bit RGB color is converted to 2‐bit RGB color. An adaptive compression algorithm of grey scale has been developed to minimize the image deterioration, which enables to select an appropriate parameter according to the types of images and the position on the screen. By a specific function of RGB point‐to‐point gray‐scale transformation, the picture shows better effect than the traditional processing method. The simulation and experimental results verify the effectiveness of the adaptive compression algorithm.

46‐2: Invited Paper: Ultimate Resolution Active Matrix Display with Oxide TFT Backplanes for Electronic Holographic Display

Oxide TFT backplane with 1μm channel length was developed for the application to electronic holographic display. Spatial light modulator (SLM) panel with 3μm pixel pitch was designed and successfully fabricated. The resolution of SLM panel was 16K by 3.2K and the diagonal length of active area was 2 inch. Fabricated SLM panel was ECB mode reflective type LCD panel, which could modulate the phase of incident light more than 2π. 3D image was successfully reconstructed with fabricated SLM panel. Vertical channel oxide TFTs are proposed for the switching device of 1μm pixel pitch. Oxide TFTs with ultra short channel length can be an enabler of the active matrix display with ultimate resolution.

5-5 高輝度反射型フルカラー液晶ディスプレイ(R-OCBセル)の光学特性

5-5 高輝度反射型フルカラー液晶ディスプレイ(R-OCBセル)の光学特性

COLORIMETRIC PROPERTY OF GUEST-HOST LIQUID CRYSTAL DISPLAYS

A bright reflective LCD without a backlight is a key device for portable information systems. The guest-host LCDs use the absorption anisotropy effect of dichroic dyes and have a wide viewing angle cone. The GH-LCD does not need complicated designs of optical compensation in birefringence or optical rotatory power modes. One of the applications of GH-LCDs is a black and white display which works as a light shutter of a full color reflective display with micro-color filters. It is necessary to mix dyes for an achromatic display. The Newton-Raphson method is useful for the calculation of optimum dye concentrations in order to display the designed color. In this work, the judgement of the calculated results is discussed. As a result, the calculated result with Newton-Raphson method is quickly and easily evaluated. The process gives us a helpful guideline in the fabrication of the reflective color LCDs and it is expected that the precise color matching improves the quality of LCDs.

74‐2: Development of a Novel Reflective Display System with Multi‐primary Color for Digital Signage

We have developed four primary‐color reflective LCD and have improved yellow and red color saturation. The color gamut area of the developed LCD meets to the standard for printing (SNAP) which is defined for reproduction quality in newsprint production. The developed LCD has also a wide color gamut, wide operating‐temperature range and high‐quality moving images. It is suitable to realize future digital signage for outdoors.