Contents

Abstructs of Reviews

Pattern Formation in Liquid Crystals -Now and Future -

Shoichi KAI and Yoshiki HIDAKA
Graduate school , Kyusyu University
6-10-1 Hakozaki, Higashi,Fukuoka,Fukuoka 812-8581 JAPAN
E-mail: kaitap@mbox.nc.kyusyu-u.ac.jp
E-mail: shftap@mbox.nc.kyusyu-u.ac.jp

Abstract�FPhysics of pattern formation in liquid crystals in non-equilibrium states is discussed. Based on universal concepts behind individual approaches for pattern formation currently carried out in non-linear dynamic systems, the importance of such research in the general physics of liquid crystals is described. In particular, dissipative patterns in the state far from equilibrium due to the electrohydrodynamic instability (EHD) in nematics are described in detail as a typical example. Although linear phenomena in EHD have been well understood already, many interesting non-linear-phenomena are still unsolved and include a rich variety of research subjects. We also introduce physics of other phenomena�Gpattern dynamics of interfaces between two different liquid crystal phases, viscous fingerings, disclinations and defects dynamics appearing in relaxation processes to equilibrium phases, and pattern dynamics due to director walls under the rotating magnetic field. Advantages of liquid crystals for studying these subjects are given. Finally the prospect for material physics as well as statistical physics and the future application to engineering fields are also discussed.
Keywords:Dissipative structure, Self-organization, Non-linear dynamics, Transport coefficient, Soft-mode turbulence

Application of FLC…NAFLC Materials to Active-Matrix Devices

Kohki TAKATOH
Toshiba Co.,LTD
1 Toshiba-cho, komukai, Saiwai, Kawasaki,Kanagawa 212-8582 JAPAN
E-mail: kohki.takatoh@toshiba.co.jp

Abstract:The improvement for moving picture quality is becoming critical in the market for large size TFT-LCDs. To reduce the degradation of moving pictures, not only the realization of the fast response of liquid crystalline materials but also the introduction of the period in which the light is shuttered after each picture is critical. For this method, the application of ferroelectric or antiferroelectric liquid crystalline materials to TFT-LCD is indispensable. In this article, first the specification for the properties such as spontaneous polarization, saturated voltage and response time to realize TFT driving is explained. Finally, …U candidates for TFT-LCD, twisted FLC mode, monostable FLC mode, DHF mode, APD mode, CDR mode and the application of frustrated phase are discussed.
Keywords:FLC, AFLC, TFT-LCD

Liquid Crystal Microemulsions

Jun YAMAMOTO
ERATO
5-9-9 Tokodai, Tukuba, Ibaraki 300-2635 JAPAN
E-mail: jun@narolc.jst.go.jp

Abstract:We studied the liquid crystal micro-emulsions consisting of a mixture of thermotropic and lyotropic liquid crystals. For the first time we report a novel transparent nematic phase, where the nematic director is locally distorted by the randomly dispersed inverse micelles. Thus, the system is isotropic in nature, nevertheless nematic order is completely accomplished. Inverse micelle concentration dependence of isotropic to transparent nematic phase transition temperature is consistent with our thermodynamic analysis, which includes Frank distortion free energy density accompanied by the usual Ladau-de Genne free energy density. Using dynamic light scattering methods, the collective translational diffusion motion of inverse micelles was shown to be accelerated by the distorted nematic director field.
Keywords:Liquid crystal micro-emulsion , Transparent Nematic , Quenched Disorde , Collective Effect , Dynamic Light Scattering

Optical System for Liquid Crystal Projectors

Yoshitaka ITOH
Seiko EPSON CO.,LTD
3-3-5 Yamato, Suwa, Nagano 392-8502 JAPAN
E-mail: ito.yoshitaka@exc.epson.co.jp

Abstract:Liquid crystal projection displays (LC-projectors) have recently come into wide use as large screen displays in the information technology field. This is because they have the advantages of being light, compact and easy to handle. In recent years, LC-projectors have been improved remarkably with regards to brightness, uniformity and resolution. LC-projectors with a luminous efficiency of more than10lm/W have been created. Progress in LC-projectors is chiefly based on technological improvements of p-SiTFT light valves as key devices, and optical systems such as lamps and polarization converters. The present paper explains the basic concepts of typical illumination systems, and reviews the optical system and optical components of high brightness LC-projectors using three transmissive-type light valves.
Keywords:Liquid crystal, Projector, Optical system, Optical efficiency, Polarization conversion

Liquid crystals reversibly fixing full color information
-A new type of cholesteric liquid crystal with potential use as material for re-writable paper-

Nobuyuki TAMAKI
National Institute of materials and chemicals
1-1 Higashi, Tsukuba, Ibaraki 305-8565 JAPAN
E-mail: tamaki@nimc.go.jp

Abstract:We have discovered a new type of cholesteric liquid crystal that has a reasonably fast response time in the liquid crystalline phase and shows stable molecular ordering below 80�Ž in the solid state obtained by rapid cooling from the liquid crystalline phase. By changing the temperature at which rapid cooling started or by changing the degree of photoisomerization of photochromic compounds embedded in it, any colors chosen from the visible spectral region were reversibly fixed as interference colors. It has been further observed that the compound shows surface-directed self-assembly in a helical molecular ordering, and forms an optically reflecting solid film on spin-coating from solutions. All these features can be understood as properties for the liquid crystals of medium-molecular-weight with a mass unit over 1000. These properties of cholesteric liquid crystals make it possible to realize a re-writable full color recording in a photon or a thermal mode.
Keywords:cholesteric, color, recording, photochromism, photoisomerization, azobenzene, self-assembly, solid film, medium molecular weight