Contents

Abstructs of Reviews

New Turns of Liquid Crystals in Tribology

Ken NAKANO
Faculty of Tech. Yokohama National University
79-7, Tokiwadai, Hodogaya-ku, Yokohama 240-8501 JAPAN
E-mail: nakano@ynu.ac.jp

Abstract : Tribology is the science and technology of two interacting surfaces in relative motion and of related subjects and practices. In recent research into tribology, the possibility of using liquid crystals as lubricants or additives has been investigated, and their excellent lubricating properties have been revealed. It has been also reported that a friction coefficient can be controlled by applying electric fields across liquid crystal lubricating films, such as in the control of optical characteristics in liquid crystal displays. In this paper, the following topics are introduced; relations between liquid crystals and tribology through boundary films at solid-liquid interfaces; the possibility of using liquid crystals as lubricants or additives; electrorheological effects of liquid crystals; control of lubricating conditions with liquid crystals.
Keywords : liquid crystal, tribology, lubrication, lubricant, additive, electrorheological effect

Columnar Mesophase|The Diversity of Chemical Structure and Intermolecular Interactions in Mesogens|

Yo SIMIZU
CREST
1-8-31 Midorigaoka, Ikeda-city, Osaka 305-8565 JAPAN
E-mail: yo-shimizu@aist.go.jp

Abstract : Since the discovery of discotic liquid crystals in 1977, a variety of studies have revealed that columnar mesophases could exist as a result of molecular species with wide variations in chemical structure of the mesogens, although it was thought to be one of the characteristics of molecular order in discotic liquid crystal. In this article, the conventional disc-shaped mesogens forming columnar mesophase are briefly reviewed and columnar mesogens possessing unconventional chemical structures are shown as the diversity of specific intermolecular interactions for the formation of columnar structure.
Keywords : columnar liquid crystal, discotic liquid crystal, specific intermolecular interaction, metallomesogen, micro-segregation

Conformation and Ordering of Chain Molecules in a Liquid-Crystalline Environment

Noritaka KIMURA
Dept. of Biongineering, Nagaoka University of Technology
1603-1 Kamitomioka, Nagaoka city, Niigata-pref. 940-2188 JAPAN
E-mail: nkimura@vos.nagaokaut.ac.jp

Abstract : 2H NMR is an excellent method of high accuracy to estimate order parameters for a mesogenic core and a C-D bond directly. 1H NMR may be also applicable to small molecules in a liquid-crystalline solvent. In this review, the methods to evaluate conformations of chain molecules in a liquid-crystalline environment from 2H and 1H NMR data are briefly outlined and the results are given in the case of liquid crystals and chain molecules in a liquid-crystalline solvent.
Keywords : 2H NMR, 1H NMR, quadrupolar splitting, dipolar coupling, order parameter, rotational isomeric state approximation, chain molecule, conformation, liquid-crystalline solvent, orientation model, mean field approximation, molecular axis

Liquid Crystalline Photorefractive Materials

Takeo SASAKI
Dept. of Chem, Tokyo University of Science
1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 JAPAN
E-mail: sasaki@rs.kagu.sut.ac.jp

Abstract : The photorefractive effect of organic materials has attracted great interest recently. The photorefractive effect of organic materials was first reported in 1990. Since then, photorefractivities of galssy polymers, glassy low-molecular-weight compounds, nematic liquid crystals, ferroelectric liquid crystals, LC/polymer composites, liquid crystalline polymers and amphiphiles have been reported. The photorefractive effect is defined as the optical modulation of the refractive index of a medium as a result of a number of processes. The interference of two laser beams in a photorefractive material establishes a refractive index grating. The photorefractive effect of low-molecular-weight nematic liquid crystals has been investigated, and the photoinduced changes in refractive index in such liquid crystals has been shown to be caused by changes in the orientation of liquid crystal molecules induced by the photoinduced space-charge field. Recently, the photorefractivity of a series of FLC mixtures was investigated. Photorefractivity was observed only in the ferroelectric phase of these samples, and the time of refractive index formation was found to be shorter than that of nematic LCs. These results indicate that the mechanism responsible for refractive index grating formation in FLCs is different from that for non-ferroelectric materials, and is clearly related to the ferroelectric properties of the material.
Keywords : photorefractive effect, liquid crystals, liquid crystalline polymers, ferroelectric liqued crystals

TFT-LCD Using Antiferroelectric Liquid Crystals

Tetsushi YOSHIDA and Jun OGURA
Casio, Co.Ltd.
2951-5, Ishikawa-cho, Hachioji-city, Tokyo 192-0032 JAPAN
E-mail: tyoshida@drd.hlb.casio.co.jp
E-mail: jogura@drd.hlb.casio.co.jp

Abstract : We have conducted research on Antiferroelectric Liquid Crystals (AFLC) by particularly focusing on the pretransitional effect in the electric-field-induced AF-F phase transition of AFLC. We developed a TFT-LCD using AFLC based on the pretransitional effect of the AFLC. The AFLC device shows V-shaped electro-optical characteristics without hysteresis. We achieved a 2.5-inch diagonal 832~230 dots prototype display device which can display moving pictures in full-color. This paper explains LC materials, the device structure, the mass production process techniques, the specifications of such prototype display devices, and their performance.
Keywords : AFLC, thresholdless, V-shaped electro-optic characteristics, TFT, display Liquid Crystalline Photorefractive Materials

Holographic PDLC and its Application to Displays

Munekazu DATE
NTT
3-9-11, Midori-cho, Musashino-city, Tokyo 180-8585 JAPAN
E-mail: date.munekazu@lab.ntt.co.jp

Abstract : A holographic polymer dispersed liquid crystal (HPDLC) is a hologram with electrically controllable reflectance (diffraction efficiency). It possesses a very fine alternate structure of non-polymerizable LC and polymer. In this paper, we introduce the structures and operations of HPDLC devices and trials for display applications.
Keywords : Hologram, Polymer dispersed liquid crystal (PDLC), Reflective display, Electronic paper