Transflective LCDs Research Articles

Design of Multi-Domain Transflective LCDs for Large-Sized Signage Applications

Design of Multi-Domain Transflective LCDs for Large-Sized Signage Applications

Transmissive and Transflective Blue-Phase LCDs With Double-Layer IPS Electrodes

A double-layer in-plane-switching electrode design is proposed for transmissive and transflective blue-phase liquid crystal displays. The new design significantly reduces the operating voltage in transmissive display by 60%; in transflective displays where the bottom-layer electrodes are made of conductive reflectors, it increases transmittance to 98%, achieves single gamma driving and enhances sunlight readability.

Transmissive and Transflective Blue-Phase LCDs With Enhanced Protrusion Electrodes

An enhanced protrusion electrode is proposed for both transmissive and transflective blue-phase liquid crystal displays. For transmissive displays, the new design increases transmittance while keeping a low operating voltage. For transflective displays, it exhibits high transmittance and reflectance and a well-matched gamma curve with a single cell gap.

P‐164: A New Transflective OCB‐LCD with In‐Cell Compensation Film

AbstractA new transflective OCB‐LCD with an in‐cell compensation film in the reflective part was proposed to improve a brightness and viewing‐angle performance of the low‐voltage driving transflective LCDs. We verified that wide viewing angle range exceeding ±80° (CR >10:1), a high contrast ratio over 1000:1 and comparatively high luminance (normalized transmittance >0.75 and reflectance >0.65) could be achieved in both transmissive and reflective parts by optimizing design parameters of the LCD, even if the on voltage is lowered to 3.5V.

Transflective LCDs With Two TFTs and Single Data Line

A simplified single-cell-gap transflective liquid crystal display with two thin-film-transistors and only one data line is proposed. The simulated voltage-dependent transmittance (VT) and reflectance (VR) curves overlap reasonably well, which enables a single gamma curve driving. The need of only one data line improves the aperture ratio, reduces the fabrication cost, and stabilizes the manufacturing process.

P‐141: The Advanced Transflective IPS LCD by Photo Alignment Technology

AbstractWe have developed 2.4″ QVGA transflective IPS LCDs with novel cell configuration. Transflective LCDs have intrinsically the difference of the optical phase retardation between the transmissive part and the reflective part. In order to compensate for this optical path length difference, we have newly designed the separate LC alignments for each transmissive and reflective parts with photo‐alignment technique. The transmissive part has a homogenous liquid crystal alignment driven by an in plane electric switching field, which exhibits superb wide viewing angle characteristics. In the reflective part, the twisted liquid crystal alignment is adopted. Based on this new configuration, high reflectance and better contrast ratio can be provided without any compensation film or patterned retarder unlike conventional transflective LCDs.

Novel single-cell-gap transflective LCDs with photoalignment

Novel single-cell-gap transflective LCDs with photoalignment

P‐186: High Quality Patterned Retarder for Transflective LCDs

AbstractA patterned retarder for a transflective LCD can be fabricated by photo polymerization of a liquid crystalline monomer. It is required for the retarder that pattern size is smaller than pixel size of a LCD and that retardation of the retarder is thermally stable against over 200°C. We have optimized liquid crystalline monomer and fabrication processes of the retarder to achieve high quality patterned retarder.

Mode switching of liquid crystals improves display performance

Mobile display devices such as portable media players, satellite navigators, and laptop computers demand good readability in both indoor and outdoor settings. These stringent constraints make transflective LCDs (displays that are readable under both bright sunlight and low-light situations) a promising technology. In transflective LCDs, each pixel is divided into two parts, one transmissive and the other reflective. The limited suitability of LCDs due to their narrow viewing angles can be overcome by introducing in-plane (IPS) and fringe-field horizontal switching (FFS) modes. However, manufacturing horizontal-modeswitching LCDs requires complicated and expensive fabrication processes.1, 2 Transflective LCDs operating in a single mode and manufacturedwith a so-called single-cell-gap structure are very desirable to reduce production costs. But they require in-cell retardation layers to prevent image inversion between the reflective and transmissive modes.1, 2 Moreover, these retarders, too, have a number of significant problems, including increased operating voltage and unreliability of the materials used for their fabrication. A new optical configuration for a transflective IPS LCDwas recently reported,3 which employs a twisted-nematic liquidcrystal (TNLC) cell with a single-cell-gap structure and without in-cell retarders. Although the transmissive-mode viewing angle performance is significantly improved, the resulting reflectivemode display capability is poor, and both modes exhibit different electro-optic characteristics. Here, we propose an optical TNLC cell design for a single-cellgap transflective display in FFS mode (see Figure 1). A systematic manufacturing procedure simultaneously achieves optimal display performance of both reflection and transmission. The wavelength dispersion of the TNLC cell is suppressed effectively by introducing a half-wave plate (HWP), the best conditions Figure 1. Optical configuration of the proposed transflective LCD. HWP: Half-wave plate. QWP: Quarter-wave plate. LC: Liquid Crystal. TN: Twisted nematic.

57.4L: Late‐News Paper: Transflective LCD Combining Transmissive IPS and Reflective In‐Cell Retarder ECB

AbstractIn‐cell retarder technology enables two kinds of display modes with different features to be realized in the pixels of transflective LCDs. Using this concept, we have developed a prototype 2.2″ QVGA transflective LCD that combines transmissive IPS for wide viewing angle performance and reflective in‐cell retarder ECB for high reflectance.

57.1: Novel Pixel Design for a Transflective IPS‐LCD with an In‐Cell Retarder

AbstractWe have successfully developed 2.4″QVGA transflective IPS‐LCDs which maintains excellent transmissive performance and higher reflectance. We have an in‐cell retarder patterned only in the reflective region. And we devised the pixel design so that the reflectance became higher. We have realized transflective LCDs with sufficient outdoor readability and wide viewing angle. Furthermore, we reduced thickness of the LCD panel at the same time.

Measurement of light incident on mobile displays in various environments

Abstract— By using a single‐lens digital camera with an attached 180° fisheye lens, the incident light at the surface of a mobile display in 112 different environments, including outdoor and indoor environments and inside an automobile, were measured. The data were analyzed for some typical environments in which mobile displays are used. The results of this research can be used in the design of reflective and transflective LCDs, making maximum use of ambient light.

P-172: Micro-Contact Printing Method for Multi-Domain Liquid Crystal Alignment

We proposed a simple method for patterning alignment layers to produce multi-domain liquid crystal (LC) alignment. By micro-contact printing method, we produced multi-directional easy axis on the alignment layer using conventional LC alignment materials. Our printing method would be a very useful tool for designing a LC mode in wide-viewing LCDs or transflective LCDs.

P-231L: Late-News Poster: A Wide Viewing Angle Transflective IPS LCD Applying New Optical Design

Viewing angle performance of transflective LCDs, affected by many optical parameters such as Nz of retardation films and azimuth of slow axis, is improved when the optical parameters obey a simple rule. A new optical design is deduced from the rule, and applied for transflective IPS-LCD with a single gap structure and a twisted liquid crystal layer. A viewing angle performance comparable to transmissive IPS LCDs is realized in transflective IPS-LCD.

Technologies towards patterned optical foils applied to transflective LCDs

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68.1: A Transflective OCB LCD with Wide Viewing Angle and Fast Response

A transflective LCD with optical-compensating-bend (OCB) liquid crystal mode was proposed. The transflecctive OCB LCD possesses fast response of several milliseconds. By using the duel cell-gap technology, the normalized voltage dependence of transmission and reflection overlap. The wide viewing angle performance is performed by optimizing the parameters of the compensation films to the electrical-induced bend texture of liquid crystal layer and using incident circular-polarized light. Consequently, the viewing angle is much better than the conventional transflective LCDs.

モバイルディスプレイを利用する空間の光環境の測定

Using a digital camera with a fisheye lens, we measured the incident light at the surface of a mobile display in 112 different environments, including outdoor and indoor environments, and the interior of a car. The data were analyzed the some typical environments in which mobile displays are used. The results were usedto evaluate the clarity of reflective or transflective LCDs and to establish a method for measuring the reflection properties of mobile displays.

P-112: Transflective VA LCD with Image-Enhanced Reflector

We propose two types of VA cell structures with image-enhanced reflectors (IER) for transflective LCDs. We found that VA cells with IER can provide improved optical performance compared with a homogeneously aligned cell.

68.3: An Advanced Transflective TFT LCD using Dual Thickness Color Filter

A new advanced color filter has developed for applying a series of transflective LCDs. It doesn't only make the same color gamut in both transmissive and reflective display modes, but also increase more than 30 % of reflectance ratio from the ambient light. This special color filter structure has thinner color resister layer on reflective area than on transmissive area was called dual thickness color filter (DTCF). An irregular diffraction photolithographic (IDP) exposure technology and new color resister material were developed in order to produce this advanced color filter.

Next‐generation mobile LCDs with in‐cell retarders

Abstract— In‐cell retarders can be a major breakthrough for mobile LCDs. When a patterned in‐cell retarder replaces the external retarders on transflective LCDs, brighter and thinner transflective LCDs with lower power consumption and wider viewing angle can be obtained. Additionally, when in‐cell retarders are applied in reflective LCDs, the thickness of the LCD is considerably reduced without affecting the optical performance of the reflective LCD. This paper presents the technology needed to make in‐cell retarders and the performance of reflective and transflective LCDs with in‐cell retarders.