Reflective LCD Research Articles

A simple method for measuring the cell gap of a reflective twisted nematic LCD

A simple method is demonstrated for measuring the cell gap of reflective twisted nematic (RTN) liquid crystal (LC) cells. This method utilizes a single laser beam and crossed polarizer configuration such that Fabry-Perot effect and surface reflection are eliminated. Experimental results agree well with theory.

Holographic reconstruction with a 10-µm pixel-pitch reflective liquid-crystal display by use of a light-emitting diode reference light: errata

We reconstructed an animation made from computer-generated holograms with a reflective LCD panel that had a pixel pitch of 10 µm×10 µm and resolution of 1400×1050. Using a LED as the reference light, we could clearly observe three-dimensional images whose size was approximately 30 mm×10 mm×30 mm. Moreover, we reconstructed a color holograph by use of a simple system with a set of red, green, and blue LEDs as the reference light.

Holographic reconstruction with a 10-µm pixel-pitch reflective liquid-crystal display by use of a light-emitting diode reference light

We reconstructed an animation made from computer-generated holograms with a reflective LCD panel that had a pixel pitch of 10 mumx10 mum and resolution of 1400x1050 . Using a LED as the reference light, we could clearly observe three-dimensional images whose size was approximately 30 mmx10 mm x30 mm . Moreover, we reconstructed a color holograph by use of a simple system with a set of red, green, and blue LEDs as the reference light.

15.4: Reflective LCD Cell Gap Measurement by QHQ Compensation Method

AbstractA phase compensation method is presented for measuring the cell gap of reflective LCD. We use the so‐called QHQ compensator that is made up of two quarter‐wave plates (Q) and one half‐wave plate (H). This method is different from other compensation methods in that we can change both the orientation angle and retardation value of the compensator by rotating the quarterwave and halfwave retarders. As a result, the QHQ compensation method has a higher accuracy and a simpler procedure.

14.3: Photovoltaic Cell Integrated into a Reflective LCD

AbstractA vast majority of portable products on the market use reflective liquid crystal displays (RLCD). Taking advantage of this, we have developed Power View technology that integrates a photovoltaic (solar) panel into a RLCD. In this paper we will present principles and approaches of different displays/photovoltaic cell combinations. Both optical and electrical results on such displays will be presented. Unique requirements and solutions for such display systems in terms of both display and solar panel performances will be discussed. We will also discuss the synergy among display size, surface area, photovoltaic cell, and issues related to mobile applications. Use models that utilize this technology will be presented. Finally different Power View display prototypes fabricated in our laboratory will be demonstrated.

45.4: Invited Paper: Technica Trends of Front‐lighting Systems in Reflective Color LCD Modules

AbstractThis paper describes the recent technology light source of front‐lighting systems (FL)in the reflective color LCD modules using th cellular phone and personal digital assistance (PDA) and the newly designed methods of light guide‐plat and pipe in order to increase the brightness of LCD.

Asymmetrical Properties of Reflective LCD'S

In this paper we present results concerning reflective LCD's with different alignment layer types. We made thought-out interpretations of the asymmetrical reflectance and current responses. The asymmetry is the result of an internal voltage. In our measurements, we distinguish alignment layers, which introduce mobile ions in the LC bulk and other alignment layers, which have a layer of trapped ions at the interface with LC.

Polarizerless Nanomaterial Doped Guest-Host LCD Exhibiting High Luminance and Good Legibility

A polarizerless reflective guest-host LCD, which exhibits high luminance and good legibility has been fabricate by using NLC with Δ ε < 0 that is doped with nanomaterial molecules, fullerene C60, and dichroic dye molecules, where the NLCs are homeotroptically aligned without rubbing. It is considered that the doped C60 molecules may play a role in reducing the order parameter of the host NLC, and in turn, the contrast ratio is enhanced.

P‐29: Novel Reflective Color STN Plastic Film LCD with High Brightness and Parallax Free Image

AbstractFor the first time, a novel bright reflective color STN LCD with inner scattering reflector on polymer substrate has been developed. The adoption of polymer substrate enables LCD to lighten and to have thinner thickness. Moreover, the structure of color filters on inner scattering reflector at the low polymer substrate improves color purity and brightness added to parallax free image compared to conventional reflective LCD. In this research, we have newly developed low temperature process and stepped heating for color plastic film LCD through thin film deposition, scattering reflector with constant brightness and color filter fabrication process.

27.3: New Cholesteric Colour Filters for Reflective LCDs

AbstractIn this paper, we describe a new method to manufacture cholesteric colour filters. The cholesteric colour filter is made by a simple method, comprising one coating step and two UV exposure steps. The optical performance of the cholesteric colour filter and a reflective LCD with a cholesteric colour filter inside the cell will be discussed. The cholesteric colour filter has a high colour purity and the display shows a high contrast ratio of 35:1.

LP‐6: Design of a Quarter Wave Plate with Wide Viewing Angle and Wide Wavelength Range for High Quality Reflective LCDs

AbstractOne polarizer type reflective LCDs require a quarter wave plate. However, conventional quarter wave plate using uniaxial retardation films have poor viewing angle and high wavelength dependences. In this paper, we designed a quarter wave plate with wide viewing angle and wide wavelength range by using three biaxial retardation films. In addition, we realized a high quality reflective LCD with wide viewing angle range and high contrast ratio by applying this quarter wave plate and wide‐view polarizer to the R‐OCB cell.

P‐87: Optical Configuration of a Horizontal‐Switching Cell for a High‐Performance Reflective LCD

AbstractAn optical configuration for a horizontally‐switched reflective LCD that could provide high reflectance as well as high contrast is proposed. We have shown that the proposed configuration can provide a flat reflection spectrum with very high reflectance in the bright state experimentally and theoretically.

Electrical and mechanical properties of indium‐tin‐oxide films deposited on polymer substrate using organic buffer layer

The electrical and mechanical properties in indium‐tin‐oxide films deposited on polymer substrate were examined. The materials of substrates were polyethersulfone (PES) which have gas barrier layer and anti‐glare coating for plastic‐based devices. The experiments were performed by rf‐magnetron sputtering using a special instrument and buffer layers. Therefore, we obtained a very flat polymer substrate deposited ITO film and investigated the effects of buffer layers, and the instrument. Moreover, the influences of an oxygen partial pressure and post‐deposition annealing in ITO films deposited on polymer substrates were clarified. X‐ray diffraction observation, measurement of electrical property, and optical microscope observation were performed for the investigation of micro‐structure and electro‐mechanical properties, and they indicated that as‐deposited ITO thin films are amorphous and become quasi‐crystalline after adjusting oxygen partial pressure and thermal annealing above 180 °C. As a result, we obtained 20–25 O/sq of ITO films with good transmittance (above 80 %) ofoxygen contents with under 0.2 % and vacuum annealing. Furthermore, using organic buffer layer, we obtained ITO films which have a rather high electrical resistance (40–45 O/sq) but have improved optical (more than 85 %) and mechanical characteristics compared to the counterparts. Consequently, a prototype reflective color plastic film LCD was fabricated using the PES polymer substrates to confirm whether the ITO films could be realized in accordance with our experimental results.

LP‐4: Late‐News Poster: Reflective Color Image‐Memory LCD Using Ferroelectric Film on LC Glass Substrate

AbstractA 2.8″‐diagonal reflective image‐memory LCD using ferroelectric film for memory elements, which enables ultra‐low‐power consumption, is fabricated on a glass substrate for the first time. The asymmetrical feature of the hysteresis loop is improved by symmetrical ferroelectric capacitor configuration, and achieved an image‐memory color LCD with good quality.

34.3: D‐ILA™ Device for Top‐End Projection Display (QXGA)

AbstractWe have developed reflective type active matrix LCD (D‐ILA™) for Top‐End projection display which provide image of high brightness, extra high resolution (QXGA), and high contrast ratio. This new D‐ILA™ technology enable it to display the entire spectrum of high definition television as well as high‐resolution computer images, and also meet the requirements of digital cinema.

26.1: Simple and Accurate Optical Reflection and Phase Compensation Methods for Reflective LCD Cell Gap

AbstractWe developed two fast, simple, and accurate optical methods for reflective LCD cell‐gap measurements. One method uses optical reflection, while the other uses optical phase compensation. They have higher accuracy, simpler setup and procedure, and lower cost than the present optical interference method. The typical measurement accuracy is about 0.05, 0.1, and 0.3um respectively, for phase compensation, optical reflection, and optical interference methods.

33.3: Applications of New Fluorinated Liquid Crystals of Fused Ring Systems for Active Matrix LCD

AbstractWe have prepared new series of liquid crystals of fused ring systems. By using the advanced LC materials, we have achieved LC mixtures having low birefringence for a reflective LCD and showing 10 ms of very quick response for LCD‐TV.

39.1: New Reflective Color Display Technique Based on Total Internal Reflection and Subtractive Color Filtering

AbstractWe present a reflective color display technique using a configuration of subtractive color filtering regions to control total internal reflection (TIR) in prismatic microstructures. The ability of the prismatic surface to efficiently redirect ambient light rays toward the viewer and the use of subtractive color filters result in a bright, easily legible, low power color image which has a four‐fold improvement in reflectivity over conventional RGB reflective LCD displays. A key advantage of this technique is the ability to switch between the highly reflective and intensely colored states with only about a half‐micron movement of the controllable subtractive color filter.

40.4: Two‐Panel Architecture for Reflective LCD Projector

AbstractA new two‐panel architecture is discussed for projection systems based on liquid crystal on silicon (LCOS) panels. It is enabled by ColorLink's ColorSwitch™ and ColorSelect™ technologies. A first prototype has demonstrated performance of 325:1 contrast and 400 lumens using a UHP 120W lamp. This paper will cover system design and function, and will include a comparison of performance to alternative single and three panel approaches.

Operation efficiency measurements and subjective evaluations for tasks on hardcopy and various displays

The final goal of this study is to clarify the humaninterface requirements for &#x201C;Digital Paper&#x201D;. Operation efficiency measurements and subjective evaluation were carried out, as a first step to discern the differences between hardcopy and softcopy for the same tasks. Simple tasks were given to 25 subjects using hardcopy and three displays: CRT, transmission type LCD with back-light, and reflective type LCD. The reflective type LCD was used in two conditions: with desk light, and without desk light. Answer speeds and correct answer rates were measured in an objective evaluation. Questionnaires on viewing ease and degree of fatigue were given to the subjects in a subjective evaluation. The objective evaluation showed only a slight difference between the interface styles; the subjective evaluation showed, on the other hand, the clear superiority of hardcopy to the other display styles.