Contents

Abstructs of Reviews

Molecular Model for the Emergence of Anticlinic Tilting and Antiferroelectricity in Smectic Liquid Crystals

Atsuo FUKUDA and Jagdish K. VIJ
Dept. of Electronic and Electrical Engineering, Trinity College, University of Dublin
E-mail: afukuda@seagreen.ocn.ne.jp

Abstract : Antiferroelectricity in the chiral smectic CA phase (SmCA–) is produced indirectly by its anticlinic structure but not directly by the dipole-dipole interaction. As the first step for understanding the antiferroelectricity, we have tried to clarify the most important intermolecular interaction that stabilizes the anticlinic structure in the achiral smectic CA phase (SmCA), disregarding any weak chiral interactions and using the approximation of perfect orientational as well as translational order. Conventional dispersion and steric (packing entropy) interactions between mesogenic molecules generally promote synclinic SmC. We have shown that anticlinic SmCA can be stabilized by interlayer orientational correlations between transverse molecular dipoles located in the flexible chains, i.e. the dynamical pairing of the dipoles in adjacent layers. Such correlations are not sensitive to chirality, and thus the theory accounts for the formation of the anticlinic phase in compounds and mixtures consiting of achiral molecules as well as racemates. By using the model potentials, we have constructed a simple phase diagram that contains SmA, SmC, and SmCA. This model is not in contradiction with existing experimental data, but we cannot exclude that some other specific interactions, particularly steric ones, may play an important role in stabilizing anticlinic SmCA.
Keywords : anticlinic SmCA, antiferroelectric liquid crystal, dipole orientational correlation, molecular theory, SmA-SmC-SmCA phase diagram

Field Sequential LCOS Displays

Toshiyasu EGUCHI
Victor JVC. Co.
E-mail: eguchi@krhm.jvc-victor.co.jp

Abstract : Liquid crystal display panels for projection systems usually use poly-silicon TFT in the transparence mode. On the other hand, reflective mode display panels of a liquid crystal on silicon (LCOS) has lately attracted considerable attention. Liquid crystals in LCOS are directly driven by transistors on the single crystal silicon. The LCOS exhibits high performance of driving and its main advantages are high aperture ratio and high resolution image from a small display area. @This paper explains the basics of the projector using LCOS with three panels. We also present the examination and the results of the prototype LCOS which is developed to perform the driving by a field sequential method. We also introduce LCOS applications for the development of single panel, two panels projector, head mounted display, and so on.
Keywords : LCOS, field sequential, homeotropic alignment, fast response, projector, head mounted display

OCB-mode LCD with Wide-viewing Angle for High Quality Movie Display

Kenji NAKAO and Hirofumi WAKEMOTO
Toshiba Matsushita Display Technology Co., Ltd.
E-mail: kenji.nakao@tmdisplay.com

Abstract : Recently, the demand for liquid crystal televisions (TV) has rapidly increased. The enlargement of the screen size and improvement of the picture quality have also rapidly advanced. The picture quality evaluation technique of the TV image is not well enough established, though a full-color animation display is required in liquid crystal TV. Of high importance is a wide viewing angle and the high-speed response. A new evaluation parameter corresponding to these characteristics is proposed in this paper, and the main features of the newly developed OCB mode liquid crystal display is explained. Moreover, bend transition technology, optical conpansate technology, and high-speed drive technologies, which are key technologies of the OCB mode liquid crystal display, are outlined.
Keywords :liquid crystal television, OCB mode, high-speed response, wide-viewing angle, evaluation technique, bend transition

Anisotropy of Rubbed Polyimide Film to Align Liquid Crystals

@Ichiro HIROSAWA
Spring 8
E-mail: hirosawa@spring8.or.jp

Abstract : Reflection ellipsometry can sensitively characterize anisotropy of rubbed polyimide film, since polarization of reflected light is insensitive to residual retardation of glass substrates. Anisotropic elements of dielectric tensor and thickness of an upper molecular oriented layer in rubbed polyimide film can be estimated from observed anisotropy in polarization of reflected light. The thickness and a dielectric coefficient of a lower random layer can also be determined. Reflection ellipsometry revealed that the effects of rubbing, soaking into solvents and annealing on anisotropy of rubbed polyimide film largely depend on the type of polyimide used. It was found that the relationships between anisotropy of rubbed polyimide film and the pretilt of the liquid crystal also strongly depend on the type of polyimide used. The preliminary result of recent grazing-incidence-X-ray scattering experiment is also reported.
Keywords : ellipsometry, rubbed polyimide film to align liquid crystal, reflected light, grazing-incidence-X-ray scattering, anisotropy

Electric-Field-Induced Orientation of Polar Organic Nanocrystals in a Disperse System

Tsunenobu ONODERA/Hitoshi KASAI/Hidetoshi OIKAWA/Hachiro NAKANISHI
Tohoku University
E-mail: ono@mail.tagen.tohoku.ac.jp

Abstract : The present review describes an electric-field-induced orientation of polar organic nanocrystals having a permanent dipole moment dispersed in a medium, which was fabricated by the reprecipitation method. This dispersion system would exhibit both crystal and liquid properties, and can be regarded as a new concept of "Liquid-and-Crystals" system, not being an ordinary "Liquid Crystal". Actually, it was confirmed that DAST (4'-dimethylamino-N-methylstilbazolium p-toluenesulfonate) nanocrystals were reversibly oriented in the dispersed liquid by applying a DC or AC electric field. In other words, the dispersion system was converted from the random to the oriented phase, which was evaluated by the contrast ratio from the changes of absorbance, depending on crystal size, strength of electric-field, frequency of AC electric field, and polarimetric properties of the probe light. In addition, in-situ observation of electric-field-induced orientation for DAST nanocrystal was performed using an optical microscope.
Keywords : organic nanocrystal, reprecipitation method, liquid and crystals, polar crystal, DAST, electric-field-induced orientation