Yasushi Kawata

The alignment of nematic liquid crystals on photolithographic micro-groove patterns

Abstract The alignment of nematic liquid crystals on micro-groove patterns was studied. It has been found that the order of the alignments is determined by the edge shape, spacing, and line pitch of the micro-groove patterns. On coarse patterns, with pitches greater than 2 μm, striped patterns of the liquid crystal alignment were observed using polarized light which manifested different orientations of the liquid crystals on the top, edge, and bottom of the grooves, respectively. On fine patterns, with pitches less than 2 μm, a uniform device-quality alignment has been realized, with which twisted nematic cells were constructed in combination with the rubbed alignment layer on the opposite substrate. Their viewing angle characteristics and tilt orientations of the director were also investigated.

31.3: Viewing Angle Controllable LCD using Variable Optical Compensator and Variable Diffuser

We have developed a dual-use-LCD, which can switch viewing angle mode between the wide viewing angle mode and the narrow viewing angle mode. In the narrow viewing angle mode, this display prevents viewing from more than 45 degrees angle. Furthermore, the power consumption is 1/3 of the wide viewing angle mode.

Polysilane spherulites and their high photoluminescence quantum yields

Large polysilane spherulites have been observed. The spherulites were prepared by controlling the removal rate of solvents from poly(n-butyl-n-pentylsilane) under a xylene atmosphere. The diameter of the spherulites was greater than 0.1 mm. The structure of the spherulites was compared with that of the polysilane powder by polarized microscopy, SEM, DSC, and x-ray diffractometry. A high photoluminescence quantum yield of 0.3 was obtained for the spherulites.

Driving voltage of reflective cholesteric liquid crystal displays

The reflective cholesteric texture mode between planar and homeotropic textures, which can achieve a high contrast ratio, needs to be coupled with an active matrix drive scheme such as a method using thin film transistors. In this article, the threshold voltage of the cholesteric–nematic phase transition, an important characteristic related to the requirements of active matrix drive schemes, is discussed. We investigated the role of the cell gap in determining the reflectance, and studied the effects of varying the nematic liquid crystal and chiral component of the cholesteric mixture. The cell gap needs to be optimized for lower threshold voltage and higher reflectance. The chiral component and the nematic liquid crystal both have a strong effect on the threshold voltage. On the basis of these results, novel chiral materials are proposed. This study demonstrates that some of these materials successfully contribute to the reduction of the threshold voltage.

Denatured tris(quinolin-8-olato)aluminium: a new material for organic electroluminescent cells

Tris(quinolin-8-olato)aluminium (Alq3) was denatured by a heating process. The denaturation was followed with infrared spectroscopy, differential thermal analysis and elemental analysis. The denatured Alq3 showed electroluminescent (EL) characteristics no weaker than normal Alq3.

Boundary condition effects on field-induced deformation modes in polymer dispersed liquid crystals

Electric field-induced deformation modes, which are considered one of the causes of the hysteresis in the V-T response of polymer dispersed liquid crystal (PDLC), were investigated. We constructed model PDLC cells with varied alignment treatments at the interface of the liquid crystal droplets. The electric field-induced deformation modes of the liquid crystals in the model cells were analyzed by polarized microscope observations. Our results suggested a possible way to hysteresis-free PDLC devices.

Control of nematic liquid crystal alignment using stripped film method

We have previously reported that the surface of a substrate fabricated using the stripped film method gives a uniform orientation of both the nematic director and pretilt angle. However, this alignment layer generates only a low pretilt angle of about 1.5°. The stripped film surface fabricated using the substrate constructed with three kinds of organic film, polyvinyl alcohol base film (Vinylon film, KURARAY Co.), polyvinyl alcohol (PVA) adhesive agent and polyimide film (AL-3046, Japan Synthetic Rubber Co.), generated unique characteristics of the pretilt angle of nematic liquid crystals. We propose under certain process conditions, the stripped film surface is capable of generating a high pretilt angle of about 10° which is much higher than the pretilt angles of the polyimide and PVA alignment layers fabricated by the conventional rubbing method.

P‐37: Study of the Ergonomics Requirement for Color Difference in Electronic Displays

We have studied the dependency on color chroma and hue for allowable and optimal levels to color difference. The deeper the chroma, the wider the areas of optimal and allowable limits. The plot of each limit for deep RGB on the chromaticity diagram shows that the width for chroma is wider than that of hue area.

P-38: Comparison of the Odiousness by Various False Colour Motion Blurs in LCDs Caused by Various Factors

We have evaluated the odiousness by various false colour motion blurs in LCDs with respect to each factor to generate the blur. In the case of different colour hue blur, we found that the optimal and allowance levels of odiousness can be expressed by the average of PBET value.

Subjective Evaluation Based on Analysis of Correlation between Physical Properties and Visualization of Various Motion Blurs on LCDs

We analyzed the correlation between three kinds of visualization of the motion blurs (colour of blurs, luminance of the blur and sharpness of object images) and physical properties in regard to image properties and panel characteristics. We also performed subjective evaluations to specify optimal or allowable level of motion blurring with various images on one CRT display and four types of LCDs with various characteristics.