Yoshio Koike

41.1: A Super-High Image Quality Multi-Domain Vertical Alignment LCD by New Rubbing-Less Technology

An MVA-LCD (multi-domain vertical alignment LCD) that provides super-high image quality has been developed by newly introduced rubbing-less technology. A newly introduced “protrusion” designed on the TFT substrates and on the color filter substrates automatically controls the directors of the LC molecules. By this technology we have successively developed four-domain 15″ MVA-TFT units that provide extremely wide viewing angle of more than 160 degrees, a high contrast ratio of 300:1 or more and a fast response of less than 25ms.

40.1: A New MVA-LCD by Polymer Sustained Alignment Technology

A new MVA-LCD using Polymer Sustained Alignment technology (PSA-LCD) has been developed. This technology can realize a stable alignment with protrusion free structure by polymer sustainment. PSA-LCD has established high brightness, high contrast ratio and fast response speed.

The Effect of Repeated Operation on Electrochromism in an All-Solid-State Device Using Li-Doped MgF2 Thin-Film Electrolyte

We have fabricated a thin-film electrochromic device consisting of WO3 and Li-doped MgF2 films. Although the device exhibited excellent coloration and bleaching response (coloration period: ~100 ms, bleaching period: ~200 ms), the following changes in the device characteristics were observed upon retreated operation: 1) bleaching was impaired, 2) spontaneous coloration increased while spontaneous bleaching decreased and 3) the threshold voltage for coloration decreased. We have found that these changes can be attributed to the change in the free energy or the Li+ ion.

3.1: MVA LCD for Notebook or Mobile PCs with High Transmittance, High Contrast Ratio, and Wide Angle Viewing

We have developed a new MVA-LCD with high transmittance comparable to a TN-LCD. We stacked a pair of quarter wave plates and stabilized the molecular alignment by dividing each pixel and arranging fine slits and nipple-shaped protrusions. The quality affordable for desk-top monitor is realized for mobile display.

Inclined Homeotropic Alignment by Irradiation of Unpolarized UV Light

Inclined homeotropic alignment was realized by irradiation of unpolarized ultraviolet light on a polyimide film that originally exhibited homeotropic alignment. Unpolarized UV light was irradiated from an oblique direction (45-degree inclined angle) once. The liquid crystal cell with a pair of inclined homeotropic aligned substrates and nematic liquid crystal with negative dielectric anisotropy exhibits a high contrast ratio (over 1000) with a crossed Nicols configuration and a bright transmittance (same as a TN cell, around 35%).

39.4: A New MVA‐LCD with Jagged Shaped Pixel Electrodes

We have developed a new MVA-LCD with fast gray-scale response characteristics. The newly designed jagged shaped pixel electrodes give the oblique electric field and effectively control the LC alignment not only statically but also dynamically. We have realized the response time of 30ms (1/3 of the conventional MVA) for any gray-scale switching keeping other advantageous characteristics same; CR, viewing range etc.

Effect of surface states of WO3 on the operating characteristics of thin film electrochromic devices

Abstract The effect of gas adsorption at the WO 3 -MgF 2 interface on the operating characteristics of a thin film electrochromic device consisting of WO 3 and MgF 2 were investigated, and the results were discussed from the viewpoint of surface states of the WO 3 film. As a result of gas adsorption the coloration speed and efficiency are increased, the threshold characteristics for coloration become sharp, the open- circuit memory becomes long and the leak current is reduced. These effects were obvious only when the adsorption was performed at the WO 3 -MgF 2 interface and water adsorption is essential to the effects. The film thickness dependence of the conductivity of as-grown WO 3 film revealed that the depletion layer of WO 3 , whose thickness is about 5000 A in vacuum, vanishes when MgF 2 film is deposited onto it. We concluded that the effect of gas adsorption can be attributed to the surface states and the depletion layer induced by the surface states of WO 3 . Using the analogy of a metal/oxide/semiconductor device, we proposed an energy band model for electrochromic devices which can explain the effects of gas adsorption systematically.

Enhancement in oscillator strength of color centers in electrochromic thin films deposited from WO2 powder

Color centers in amorphous films evaporated from WO2 powder and WO3 powder were investigated. It was found that the device using ‘‘WO2’’ film, which has a WO3‐like structure, exhibits a high‐speed response and a high optical density, which is attributed to the enhancement in oscillator strength of the color centers in ‘‘WO2’’ films. The use of a configuration coordinate model revealed that the enhancement in the oscillator strength is caused by the increase in the degree of extension of the polaron wave function in the ‘‘WO2’’ film. The absorption band of the color center in ‘‘WO2’’ exhibits a low‐energy shift as compared with that in WO3, which supports the increase in the degree of the small polaron extension in ‘‘WO2.’’ We also studied the electrical conductivity, density, ir absorption spectra, and voltammograms of the ‘‘WO2’’ and WO3 films. These results suggest that the increase in the degree of the extension of the polaron wave function is caused by some change of the lattice condition which is int...

25.3: An Ultra-High-Quality MVA-LCD Using a New Multi-Layer CF Resin Spacer and Black-Matrix

An ultra-high-quality MVA-LCD has been developed using a newly designed CF. The Cr black-matrix was replaced by multi-layer CF resin, which was also used to eliminate the conventional bead spacer. The protrusions that are essential to building rubbing-less MVA panels are stacked on the multi-layer CF resin coated by ITO to prevent electrical shorting between the CF and TFT substrates and to maintain the appropriate cell gap. This beadless MVA panel improves the transmittance and cell gap uniformity. Moreover, this new design removes Cr BM from the CF structure and eliminates both spacer dispersion and rubbing from the MVA panel process.

Four-Domain Divided Inclined Vertical Alignment by Irradiation of Unpolarized Ultra Violet Light

A four-domain divided vertically-aligned liquid crystal panel (LCP) has been realized by irradiating unpolarized UV light on a vertical alignment layer through an optical mask. The liquid crystal (LC) with a negative dielectric anisotropy is filled. As the alignment has no disclination for the black state, the transmittance in the black state is the same as that with mono-domain vertically aligned LCPs, realizing a high contrast ratio of over 300. With a negative birefringence film, the fabricated LCP exhibits a wide viewing range. It has a contrast ratio of over 10 at any inclination angle of within 60° at any viewing azimuth and has almost no gray scale inversion.