Contents

Abstructs of Reviews

Development of Low-Temperature Polycrystalline Silicon TFT-LCDs

Yasuyoshi MISHIMA
Fujitsu Lab., Co.
10-1 Morinosatowakamiya, Atsugi, Kanagawa pref., 243-0124 Japan

Abstract : Low-temperature polycrystalline Silicon TFT technologies have been developed for a low-cost glass substrate LCD with monolithic drivers. Monolithic drivers reduce the cost of TFT-LCDs because of the reduction of driver chips of Si IC on TFT-LCDs. These technologies give a flexibility in circuit design and are developed in the field of "System on panel". New low-temperature processes must be developed to utilize this technology. In this paper, we discuss the main low-temperature processes ; the formation process of polycrystalline silicon films, the CMOS fabrication process and the insulator process. These processes were compared with the other fabrication processes. A TFT process using these low-temperature processes is shown in comparison to an a-Si : H TFT process. The designs of TFT structures, pixel configuration and peripheral circuits are also introduced in conjunction with characteristics of TFTs that are influenced by the material properties. Finally we expect the future trend of low-temperature polycrystalline silicon TFT-LCDs in the application field and the future process technology in this field.
Keywords : Low-temperature polycrystalline Silicon, CMOS fabrication process, System on panel

Chirality-Dependent Properties of Smectic Liquid Crystals

Tetsuo KUSUMOTO
Sagami chemical Institute
4-4-1, Nishi-Onuma, Sagamihara, Kanagawa pref. 229-0012 Japan

Abstract : In order to prepare ferro- and antiferroelectric liquid crystals for fast switching, many types of optically active compounds were designed and synthesized. Herein we survey the relationship of the structures near the chiral center and the properties of ferro- and antiferroelectric liquid crystals. Furthermore we report that a novel dichiral liquid crystal of structure2-[4-((R)-2-fluorohexyloxy)phenyl]-5-[4-((S)-2-fluoro-2-methyldecanoyloxy)phenyl]pyrimidine exhibits a new optically isotropic phase as well as an endothermic transition enthalpy on cooling. The effect of chirality on the transition behavior is discussed.
Keywords : Smectic Phase, Chirality, Ferroelectric Liquid Crystal,Antiferroelectricic Liquid Crystal

High-Performance Reflective Cholesteric Polarisers

Jun NAKANOWATARI
Dept. of LC, Merck Japan Co.
1-8-1, Shimomeguro, Meguro-ku, Tokyo 153-0064 Japan

Abstract : The improvement of the light transmittance of LCD panel and the reduction of energy consumption are important technical requirements for applications such as PC notebooks and portable appliances. In this paper, we present the optical properities of reflective polarisers made from wide waveband cholesteric film, which gives linearly polarised light with high efficiency as well as related technologies.
Keywords : Cholesteric phase, linearly polarised light

Molecular Theory of Phase Transitions of Liquid Crystals Based on the Density Functional Form of the Free Energy

Tomonori KODA
Faculty of Tech., Yamagata Univ.
4-3-6, Jounan, Yonezawa, Yamagata pref. 992-0038 Japan

Abstract : Liquid crystals are distinguished by the density distribution of molecular positions and directions. There is a theory which discusses phase transitions of liquid crystals as changes in density distribution. The starting point of this theory is the density functional form for free energy. When the temperature and density of the system are fixed, the most favorable structure is given by the density distribution which minimizes the free energy. The form of the free energy takes contributions of molecular property by averaging the integration of the molecular pair potential. Then the theory enables us to discuss the relation between properties of molecules and the behavior of liquid crystals. In this article, we first explan why liquid crystalline phases are distinguished by density distribution. Then the density functional form of the free energy in the mean field apporoximation is discussed. After that we apply the theory to the problem of the successive phase transitions of chiral smectics. We discuss the role of the distinction of the molecular head and tail for the successive phase transitions. The theory indicates that one of the origins of the successive transitions is the head-tail distinction of a molecule.
eywords : molecular theory, density functional, phase transition, chiral smectic