Contents

Abstructs of Reviews

Photoalignment \Alignment Process Overview from the Manu-facturing Point of Views

Masaki Hasegawa
IBM, Japan


Abstract : Photoalignment technology has attracted a great deal of display panel applications, because it offers the potential of improving the conventional rubbing process and multidomain for wide-viewing-angle. In this paper, an overview and the technical trends of photoalignment are described. Five types of photoalignment, isomerization, dimerization, decomposion, crosslinking, combination of crosslinking and decomposition, are introduced. Typical material structures, and newly developed molecules of each photoalignment type are also shown. The mechanism of the decomposed type photoalignment is discussed based on the results of several measurements, which include UV and IR absorption spectra, order parameter, and anchoring energy. We also report the status, problems, and current solutions to the problems incurred during the rubbing process. Based on this analysis, we summarized the requirements for the alignment process. The cost and characteristics of photoalignment are compared with those of the rubbing method, and its practical availability is discussed from a production process point of view.
Keywords : alignment, nematic liquid crystal, UV, surface

Low Power Liquid Crystal Display Technology

Haruhiko Okumura



Abstract : Low power liquid crystal display (LCD) technology is one of the most important technologies of personal computer systems, because power consumption of an LCD is higher than half that of the total note-PC power consumption. It brings about long battery life and light-weight portable equipment. In this paper, the low power LCD technologies are classified into two main parts; backlit and driving power technology, and potential technologies including reflective type LCDs are discussed. In particular, the reflective type LCD technologies with memory are expected to be one of the most important applications that make it possible to open new markets, such as ultra-low power portable and light-weight equipment like electronic paper. Therefore, the memory and high reflectivity technologies for paper-like displays are aloso discussed.
Keywords : low power consumption, TFT�\LCD, back lit, driving circuit, refle ctive type, memory

Thermodynamic Approach to Surface Anchoring of Liquid Crystals

Hiroshi Yokoyama
Electrotechnical Laboratory


Abstract : Application of Gibbs surface thermodynamics to the surface anchoring of nematic liquid crystals is reviewed. The characteristic parameters pertaining to surface anchoring, i.e. the extrapolation length and the anchoring energy, are defined thermodynamically, by extending the dividing surface concept to the surfaces of orientationally distorted nematics. The basic concepts and limitations of the conventional phenomenological approaches to the anchoring problem are discussed on the present thermodynamic basis. Thermodynamic relations are derived, which connect the anchoring energy and the easy axis with the macroscopic variables such as temperature and composition. The thermodynamic origin of surface anchoring is discussed in the light of these relations.
Keywords : surface alignment, anchoring energy, extrapolation length, thermodynamics, nematic liquid crystal

UV-Curable Liquid Crystals and Their Application

Haruyoshi Takatsu, Hiroshi Hasebe
DaiNippon Ink Co. Ltd.


Abstract : Liquid crystalline monoacrylates having no methylene spacers between mesogenic core and acryloyloxy group (UV curable liquid crystals) have been prepared. The mesomorphic properties and application of the UV curable liquid crystals are described. Liquid crystalline monoacrylates "with spacers" have been used as precursors of side-chain type liquid crystalline polymers. On the other hand, the UV curable liquid crystals provide new application taking advantage of the rigid linkage between the polymer main chain and the mesogenic core at their polymeric state. The properties of Polymer Network Liquid Crystal Displays (PN-LCDs) and Polymer Stabilized LCDs are improved by using the UV curable liquid crystals as a component of monomers. The retardation film with designed molecular orientation and with good thermal stability is obtained by using UV curable liquid crystals showing a nematic phase at room temperature.
Keywords : monoacrylates, polymer Network, polymer Stabilize, retardation film