Yuzo Hisatake

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.

Improvement of viewing angle characteristics in a twisted‐nematic liquid‐crystal display by using a cholesteric liquid‐crystal compensation layer

Viewing angle characteristics of a twisted nematic (TN) liquid‐crystal display (LCD) have been improved by inserting a planar aligned cholesteric liquid crystal compensating layer between the TN cell and a polarizer. Dependencies of the electro‐optical characteristics of the novel LCD on the retardation, ratio of thickness to the pitch (dc/p) and twist‐sense in the cholesteric layer are discussed. A thin‐film transistor addressed LCD with a wide viewing angle has been developed based on this novel cell construction and its display performance is reported.

Viewing-angle evaluation method for LCDs with gray-scale images

— A new evaluation method of viewing-angle characteristics for liquid-crystal displays (LCDs) with gray-scale images has been studied. In this method, reverse images, excessively dark images, and excessively bright images, which are a serious problem while displaying gray-scale images, are evaluated quantitatively along with the display contrast ratio. The viewing-angle characteristics of several types of LCDs are compared using this method.

23.3: Characterization of 3D Image Quality on Autostereoscopic Displays — Proposal of Interocular 3D Purity —

We propose “Interocular 3D Purity”; a quantitative measure of the image quality of stereoscopic displays. This measure expresses how well stereopsis-disturbing images are excluded. We apply this measure to three types of display and find it to be effective in analyzing not only the dimensions of stereoscopic viewing spaces but also the smoothness of motion parallax.

44.3: Characterization of Motion Parallax on Multi-view/Integral-imaging Displays

Multi-view and integral imaging displays have a significant feature that allows people to induce better stereopsis due to motion parallax. Base on the analysis of the mechanism, we propose characterization methods of the displays. Our methods evaluate change in luminance of stereoscopic images when observers eye positions are displaced. The results show that our methods are good for showing smoothness of the motion parallax.

Viewing-angle evaluation method of color shift for LCDs with gray-scale images

— The viewing-angle characteristics of LCDs with gray-scale images were evaluated using parameters related to color. The results were compared with the subjectively estimated results. It was found that iso-curves of the maximum value of the difference in hue angle are useful in evaluating the viewing-angle characteristics of LCDs.

Viewing-angle magnification in a TN-LCD with an ultra-super-twisted liquid-crystal compensator

— The viewing-angle characteristics of a TN-LCD were improved by inserting an ultra-super-twisted (UST) liquid-crystal compensating layer between the TN cell and one of the polarizers. The viewing-angle characteristics of the LCD could be controlled by changing the optical conditions of the UST layer, such as the retardation, the dUST/p value, and the twist sense. The improved viewing-angle characteristics were confirmed by a TFT-addressed LCD developed on the basis of this novel cell construction.

Lateral-electric-field diffraction mode LCD for projection display systems

A new liquid crystal display (LCD) mode based on diffraction effects, which result from the application of lateral electric fields on the liquid crystal (LC) layer, is proposed in order to realize bright and high-contrast images in projection displays. The LC cell structure and its electro-optical characteristics are presented and its performance is compared to several other conventional liquid crystal display modes. In the new LCD, the upper and lower substrates support striped transparent electrodes which have a width and a pitch of 7 micrometers and 22 micrometers , respectively, for a typical case. The upper and lower electrodes are positioned parallel to each other and shifted by a half pitch, i.e. the upper electrodes are aligned with the spacings separating the lower electrodes. We refer to this design as the staggered inter-digital electrode configuration. Both substrates are coated with a polyimide layer rubbed in the direction perpendicular to the striped electrodes resulting in an anti-parallel LC alignment. In a typical cell, a nematic LC material with a positive dielectric anisotropy and a thickness of 5 micrometers are used. Lateral electric fields are generated between the upper and lower substrates and we therefore call this LC mode the Lateral Electric Field Diffraction (LEFD) mode. The transmission-voltage (T-V) curves of the LEFD liquid crystal cell were measured by using a polarized and unpolarized He-Ne laser beam ((lambda) equals 632.8 nm). The plane of incidence of the laser was set to be parallel or perpendicular to the longitudinal axis of the striped electrode and the transmitted light (zeroth order diffraction light) was measured by a photometer. The T-V curves did not show any dependence on the polarization of the incident light and no hysteresis was observed. The transmission was found to be about 80% when no voltage was applied. The threshold voltage was found to be about 1.8 volts and the voltage at which the minimum transmission occurred was 4.5 volts. The contrast ratio was calculated to be about 200:1. In the LEFD LCD, the effective indices of refraction in the directions both perpendicular and parallel to the striped electrodes are modified by the lateral electric field. Diffraction effects occur for all polarizations and it is therefore possible to obtain a high contrast ratio for unpolarized light. This means that the LEFD LCD does not require any polarizer. By combining this LEFD design with a schlieren optical system, it would be possible to create bright and high contrast images in projection displays. We think that the use of LEFD LCD is one of the most promising solutions to realize a very high performance in projection display systems.

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‐44: Overall Judgment by Comparison with Polish and Matt Surface for some FPDs with Analytic Hierarchy Process

We evaluated the priority order among four image quality factors:legibility/readability, sharpness/pureness, graleness/fatigue and reality/fidelity, and compared the image qualities to four surface treatments: polish, polish with anti-reflection treatment and matt surfaces as 12% and 25% haze, for three applications with main size panels: mobile-phone, PC, television by using analytic hierarchy process.