For a spacer structure in a side group liquid crystalline polyacrylate, we have reported that a segmented spacers, which consisted of oligo(ethylene oxide) and alkyl segments, promoted the mobility of a mesogen and decreased the glass transition temperature, Tg, compared with an ordinary alkylene spacer. In this work, two series of polyacrylates, xEO-Cy and Cp-qEO, were prepared to study the influence of the length and the linking-order of these segments on the thermal properties. As a result, almost xEO-Cys, which had mesogens connected to alkylene segments, exhibited LC phases while all Cp-qEOs, which had mesogens connected to oligo(ethylene oxide), had no mesophases. In the case of xEO-Cys, longer alkylene chains (y=10,11) in the segmented spacers induced crystalline phases, and for cases below y=9 a decrease of an alkylene length depressed the ranges of the LC phases. In addition, the increase of segment length of an oligo(ethylene oxide) contracted the range of the LC phase. Consequently, it was found that the hydrophilic domain, which consisted of polymer-backbone and oligo(ethylene oxide), and hydrophobic domain, which consisted of alkylene chains and mesogens, assembled each other and improved the order of mesogens, and that appropriate composition of these segments was necessary to give wide range LC phase to the polymer.

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We have shown that liquid crystals can be easily gelled by self-aggregation of low molecular weight gelling compounds in liquid crystal solvents. In one type of liquid-crystalline gels, gelling molecules form randomly dispersed networks in isotropic states of solvents. By the choice of components, a new type of the gel where sol-gel transitions occur in the smectic liquid-crystalline range of solvents can be obtained and various oriented aggregates of gelling molecules have grown in anisotropic media.

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Bistable nematic LCD is expected to realize the huge multiplexing of the simple matrix without expensive TFTS. We proposed Symmetic Bistable Twisted Nematic LCD (SBTN-LCD) that 〓Φ〓 twisted state is wilite and 〓Φ〓 twisted state is black. Analytical design formulas for SBTN-LCD were derived. The computer simulations and experiments almost agreed with the analytical design.

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A discrete-time system model was used best to describe the response characteristics of a liquid crystal device with an active matrix drive. There are two contributions to the response characteristics. The first one is associated with the active matrix drive. It depends on the electrical displacement vs. voltage characteristics of the liquid crystal cell. A simple expression for a high voltage region was obtained. The other is caused by the slow response of the liquid crystal itself, which is understood well by using a first-order delay system.

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Liquid Crystal Institute, Science University of Tokyo in Yamaguti, Onoda, Yamaguchi 756-0884 We investigated an electroptic characteristic of LCD cells using NLC with a negative Δ ε a adopting photoalignment technique, where pretilt angles ranging 87°〜89° we produceed with a good controllability. The cells fabricated in this way exhibit excellent ECB effect yielding a very high contrastratio of 200:1.

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We have investigated micro deflection liquid crystal display (MD LCD)mode with eight-division electrodes. The expectations of this electrode structure are improvement of viewing angle using multi-domain structure and realization of convenient threshold characteristics. Under He-Ne laser illumination, electro-optical characteristics was similar to that of previously reported MD LCD mode. Threshold voltage depended on the incidence polarization direction and contrast ratio was 354:1. Under white light illumination, the contrast ratio was 43:1 for homogeneous alignment state under cross nicols.

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We have investigated a scattering display mode with in- plane electrodes structure. The in- plane electrodes are patterned on one- side of glass substrate and other side of glass substrate is roughened. This roughened surface disturbs molecular orientational distribution and eventually induces the right scattering in off state. In on- state, the liquid crystal molecules are forced to align uniform due to applied electric field. Under He- Ne laser irradiation, contrast ratio obtained was 9:1 without polarizers.

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We have analyzed two peculiar phenomena observed in IPS mode LCDs. Those are electrically asymmetric behavior of liquid crystal and generation of the extraordinary domains along the driving electrodes. We have consistently explained these phenomena with consideration on flexoelectric and pre-tilt effects.

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We have investigated the transmission spectra and the viewing angle properties of the IPS mode cell using the uniaxial medium model. The transmission spectra have been described with the model using the effective birefringence, Δn_<eff/・ The viewing angle properties have also been reappeared satisfactorily with this model. We expect that the IPS device design becomes easier using this model.

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Response characteristics of gray levels in the TN and IPS modes have been studied. The value of τt-max/τ-min of gray levels in the IPS mode was below 2.5. The value was extremely small compared with that of the TN mode, which was about 20. We also elucidated that these response characteristics could be explained qualitatively from elastic energy density. It was revealed that response characteristics depend on the LC switching mode. In order to improve the response characteristics of gray levels, the IPS mode is more advantageous than the conventional TN mode.

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Novel multicolor fluorescent LCDs are demonstrated, where the anisotropic blue fluorescent film, green fluorescent IN cell, and the polarizer are stacked. The fluorescent color can continuously be changed from green to blue by applying the voltage across the TN cell. Since the polarizer for the visible light is employed, the brightness increases more than two times and the difference of the color from the on-state to the off-state widens, compared to the forner fluorescent LCD mode.

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Reflective color LCDs are important key devices in future information oriented society. High utilization efficiency of ambient light for bright display is needed for design of the Reflective mode. In transmissive mode, tile brightness can be easily controlled by backlight. However, the light intensity of the reflective mode is limited within tile ambient light. The loss of the incident light in the reflective mode results in darkening the LCD panel. It is a important point of the reflective display to increase the brightness as high as possible. In order to improve the efficiency, the property of a polarizer is discussed and the guideline is presented.

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We have developed a novel reflective LCD mode. This new GH-mode is super-twisted hybrid alignment with chiral reagent. It has achieved a higher dichroic ratio at lower voltage than conventional GH mode.

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The reflective color LCD without a backlight is an important key device for the progress and diffusion of high functional portable information terminal. We have previously proposed a single polarizer reflective TN-LCD of normally white mode composed of a driving TN cell and a compensating liquid-crystal polymer film with a twist angle of the same magnitude, but opposite-handed of the LC layer. The twist angle dependence of the electro-optical properties of the LCD has been numerically analyzed, and it was found that the optimal twist angle of TN cell is about 60° because the optimal cell has high contrast ratio and retardation of the LC layer of practical use.

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We have compared the electro-optical properties of reflective color STN-LCDs with normally black and white modes. The contrast ratio of the normally white mode less depends on the direction of incident light than that of the normally black mode. There is a possibility to improve the viewing angle characteristics of reflective color STN-LCDs by using the normally white mode.

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The reflectance of reflective LCDs strongly depends on illumination. Usually a collimated light source is used for measurements. However we do not use reflective LCDs in such a circumstance in which collimated light impinges onto them. So we propose use of diffused light. We illuminate a reflective LCD uniformly from directions within a cone defined by the specified angle θ, since we assume that illumination in an office is stronger from the normal direction to the LCD. Comparing the measured reflectance with that measured in a typical office, we have found that the reflectance with θ= 30° to 50° corresponds to that measured in the office.

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Considering the polarization state of light propagating through a LC medium, we have shown that a quarter retardation plate (λ/4 wave plate) can eliminate the dependence of the reflective light intensity on the azimuthal rotation of a LC medium with respect to the direction of a polarizer. In this research, we indicate that amorphous TN structure can be applied to reflective LC display modes without losing reflective light efficiency.

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Wide viewing angle chotesteric liquid crystal displays using color filters are proposed. The filter absorbs wavelength shorter than the selective reflection band, greatly improving color shift of the selective reflection. We also achieved as high as 36% of white luminous reflectance by stacking blue, yellow, green and red cholesteric layers. Each layer has opposite twisting sense.

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