A reverse twist defect deteriorates a picture quality of an In-Plane Switching (IPS) mode display. We have proposed a simple method to evaluate the reverse twist stability using one-dimensional sine curve director profiles. The calculated stability has been corresponded to the observed phenomena. Using this method, the stability dependence on the device parameters can be investigated with facility and the deterioration due to the reverse twist defect can be predicted.

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Defect free FLCDs with C-1 uniform state have been sueeessfully fabricated by photoalignment using polyimide films as alignment Payers. The result is mterpreted by developing a phenomenologfcal theory It is theoretically shown that the weak azimuthal aehoring energy ranging in the region of 10 ^GJ/m^2 attributes to the appearance of C-1 uniform state rather than C-2 uniform state; the agreement between theory. and experiment is fairly well.

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With a view to their application to TFT-LCD, we studied smectic liquid crystal materials showing V-shaped switching. It is known that the alignment and switching properties of V-shaped switching liquid crystal materials are highly dependent on the kind of alignment layers. Therefore, we investigated many polyimide materials, which are similar in certain respects, for application as alignment layer of V-shaped switching liquid crystal materials. As a result, polyimide materials that have low polarity and low pretilt angle were found to be suitable for alignment layer of V-shaped switching liquid crystal materials. The alignment of V-shaped switehing liquid crystal materials becomes unstable due to the strong polar interaction between dipole moments of liquid crystal molecules and the polarity of alignment layers.

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We have developed Hyper Amorphous Silicon TFT(ILAST)for a display in high grade indication. HASTs require a best condillon term in both display designing. material selecting, and proeess engineering If these terms have any miss matching, indication defeels happen to LC1) like that Reverse Twist Domain. In this domain dots. liquid crystal molecules are twisted to reverse direction. In this report we show the results of analysis for this defects. Then we find that Color Filler surface roughness. electrode bus line piteh and liquid cryslal pretilt angle have good correlation wilh this Reverse Twist Domains.

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V-shaped AFLCDs are capable of displaying analog level, wide viewing angle and fast switching speed. Nevertheless, recent investigations have concluded that impurity ions in liquid crystal devices severely interfere with the device performance [1]. In this report. we have investigated how impurily ions influence the device performance of V-shaped AFLCDs applied DC voltage. Analyzing relations belween image sticking distributions in view areas and impurity ion distributions in those, we found that impurity ions in the device cause not only residual DC but also emergence of unfavorable memory effect.

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In order to obtain information about intermolecular interactions controlling mesophases, we have tried to find the relationship between crystal structures and liquid crystal behavior. Crystal structures have been determined for two 2,6-disubstituted naphthalene derivatives with highly planar core moreties: 4-octylphenyl 6-octyloxy-2-naphthoate (I) and 6-octyloxy-2-naphthyl 4-octyloxybenzoate (II). In both crystals, the largely overlapped core moieties stack alternately, leading to smectic-like layer structures. The tilt angles of long molecular axes were estimated to be 30° (I) and 50° (II), which are related to their mesophases, SmA and SmC, respectively.

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We synthesized new series of octakis(4-(N-(4-alkoxyphenyl)iminomethyl)phenoxy)cyclotetraphosphazene, [NP(OC_6H_4CH=NC_6H_4OC_nH_<2a+l>]_2]_4 (OSCTP-n), n=6-12 and octakis(4'-(4-alkoxy)biphenoxy)cyclotetra- phosphazene, [NP(OC_6H_4C_6H_4OC_nH_<2n+1>)_2]_4 (OBCTP-n), n=8,12, where n is a carbon number of end alkoxy groups. Their phase transition and mesogenicity were studied by DSC and X-ray diffraction measurements and polarizing microscope observations. We found an enantiotropic SmA phase in the series of OSCTP-n for n = 7-12 and monotropic SmA phase in OBCTP-12. We discussed the phase transition of trimer and tetramet with similar side chain groups.

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IR absorption spectra of 4-cyano-4'-alkylbiphenyl with various alkyl chain conformations were calculated with Density Functional Theory of B3LYP/6-31G(d) level. Calculated spectral patterns of phenvl ring C-H out-of-plane (CHOOP) deformation modes, which are strongly coupled with alkyl chain vibrations, show marked differences with conformational change of alkyl chain. The observed spectral patterns of CHOOP bands are well explained by the existence of 5CB conformers. Peak shifts and intensity changes of the spectra in this region with temperature are also well explained by the population changes of 5CB conformers.

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Nematic liquid crystal-solid transition curves were calculated for terminal polar-nonpolar nematic mixtures by means of regular solution theory, which is one of the thermodynamic treatments for non ideal systems. In this report, the solubility parameters of the components comprising a mixture were used to calculate the activity coefficient. As a resull, a deviation from the ideal behavior is attributed to the differences in the solubility parameters.

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This paper describes X-ray diffraction studies for smcctic A phases of 4-nitrophcnyl 4-(4-alkoxy- benzoyloxy)benzoates, 4-alkoxylphenyl 4-(4-nitrobenzoyloxy)benzoates, 4-(4-alkoxylbenzoyl- oxy)phenyl 4-nitrobenzoates, and 4-alkoxylphcnyl 4-nitrophcnyl tercphthalates. The layer spacings (d) are discussed in terms of thc molecular length (l) calculated by semi-empirical molecular orbital method and molecular arrangement.

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The effect of alkyl and alkoxy chain lengths on the layer structure of smectic A phase has been examined by an X-ray diffraction measurement for four isomeric systems; 4-R-phenyl 4-(4-octyloxybenzoyloxy)benzoates (1), 4-octyloxyphenyl 4-(4-R-benzoyloxy)benzoate (2), 4-(4-R-benzoyloxy)phenyl 4-octyloxybenzoates (3) and 4-octyloxyphenyl 4-R-phenyl terephthalates (4), (R=alkoxy, alkyl). The results are discussed in terms of change in molecular properties due to replaccment of the ester groups.

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Because mobility improves in a liquid crystalline organic semiconductor while becoming the aspect of more higher-order, it is thought that the cohesion of the molecule produces a big influence on the carrier transport. Then, we thought that we would be able to elucidate the relation between the slate of cohesion and the carder transport of the molecule by changing molecular structure and controlling the heat movement of the molecule. First of all, file dimer molecule which tied by the hydroquinone structure was synthesized, and the basic physical properties and the cartier transport characteristic were examined. The mobility of the hole in the smectic A phase was 7.5 × 10^<-4>cm/Vs for monomer (12-PNP-O6) and 8.5 × 10^4 cm/Vs for dimer (hydroquinone-dimer). These two values were almost the same. This result corresponds to there is no big change in the phase transition behavior of monomer and the dimer.

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The alignment of nematic liquid crystals (LCs) parallel to the polarization direction of laser could be induced by PI(PBGA/FDA) with a fluorene unit exposed to the laser at 355 nm in nitrogen atmosphere. The structure of PI(PBGA/FDA) irradiated with the laser in nitrogen shows no detectable chemical change, when the parallel alignment of LC is induced. The mechanism of the parallel alignment is not the photodegradation but the orientation of main chains of the polymer. It is estimated that the reason that LC alignment is dominated not by main chain but by fluorene unit is the multiplier effect of alignment force from two coplanar phenyl ring in the fluorene unit.

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A novel rubbing-free technique has been developed for LC alignment using photoaligned Chemically-Adsorbed(CA) monolayer. By using this technique, TFT LCDs have been trially-produced with good LC alignment. Molecules constracting the monolayer contain a photo-crosslinkable "chalconyl" group, and can be aligned and fixed by the irradiation of polarized UV light. The contrast of a test cell by use of the CA monolayer was about 370.

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Discotic liquid crystals possess versatile applicabilities for electronics and photonics over calamitic ones so that increasing efforts have been made on developing disk-shaped molecules, aiming at the elucidation of the structure-function relationship. We report herein a novel approach to discotic liquid crystal alignment, which was accomplished by using a thin film of a polymer bearing azobenzene side chains. A polymer film irradiated obliquely with nonpolarized light gave rise to the orientational control of discotic liquid crystals as a result of three-dimensionally photoaligned azobenzene side chains.

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Asymmetrical triphenylene derivatives containing ester or carboxylic acids as terminal substituents were synthesized and characterized by DSC, optical microscopy and X-ray diffraction. It was found that all the ester homologues are non-mesomorphic, while most of the carboxylic acid homologues show a hexagonal columnar (Col_h) mesophase. Temperature dependent infirared spectra (of the carboxylic acid derivatives indicate the existence of strong hydrogen bonding interaction in the isotropic. mesomorphic and solid phases.

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Infrared photoinduced change of liquid crystal domains was investigated for a hexagonal columnar mesophase of a triphenylene derivative. A uniform change of domains was observed when an infrared laser beam corresponding to the wavelength range with the absorption band of triphenylene core was irradiated. The texture change means that a change of the molecular alignment occurred and it seems that the direction of columnar axis depends on the direction of the incident laser beam. It could provide a novel technology to control the alignment of liquid crystals with high viscosity.

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We synthesized 4-(4'-dodecyloxybenzyloxy)benzylalcohol (a), 3,5-bis[4-(dodecyloxy)benzyloxy]-benzylalcohol (b), 3,4-bis[4-(dodecyloxy)benzyloxy]benzylalcohol (c) and 3,4,5-tris[4-(dodecyloxy)-benzyloxy]benzylalcohol (d). Their mesogenicity was studied by DSC and X-ray powder diffraction measurements, and polarizing microscope observations. In compound a and b, no mesomorphic phase was observed. In compound c and d, an enantiotropic discotic phase was observed.

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Novel cerium(IV) porphyrin sandwich complexes were synthesized and their mesomorphism was characterized by polarizing optical microscopy, differential scaning calorimetry(DSC), and X-ray diffractometry. Although the metal-free porphyrin derivatives show discotic lamellar (D_1) mesophase as reported previously, all the present sandwich complexes show a rectangular colunmer(Col_r) mesophase.

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New discotic liquid crystal with one acrylate end group(2) was synthesized. The luquid crystalline properties were characterized by polarizing optical microscopy, electronic absorption spectroscopy, differential scanning calorimetry and X-ray diffractometry. As the results, phthalocyanine(Pc) derivative(2) exhibits three kind of discotic hexagonal columnar phases(Col_hl, COl_h2, Col_h3) at the lower temperatures. On the other hand, it show a discotic tetragonal columnar phase(Col_<tet>) at the higher temperatures, in which the molecules were spontaneously homeotoropically aligned on the glass plate without any treatments for the glass surface. This result was the same as the Pc derivative(I) reported previously by Hatsusaka et.al. Subsequently the difference of structures among three hexagonal columnar phases were investigated by the X-ray diffractometry. As the results, these hexagonal columnar structures were gradually disordered as Col_h1(COl_<ho>)→COl_h2(COl_<hd>)→COl_h3(Col_<hd>).

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Liquid crystallinity of a series of N-methyl-trans-stilbazolium alkyl sulfates (MeStz/C_0H_<2n+1>OSO_3, n = 8 - 18) were studied. MeStz/C_nH_<2n+1>OSO_3, where n = 8 and 10, showed no liquid crystalline phase. The derivative of n=12 showed a fan shaped texture at temperature region between 100℃ and 149℃ XRD analysis of the derivative can identified as a smectic E phase or smectic X phase with more complex structure in the lateral direction. The derivatives of n=16 and 18 showed smectic A phases, which showed more than two diffraction peaks in XRD pattern due to the layering structure.

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Oblique photoalignment technique using non-polarized visible light applied to a chiral nematic (cholesteric) liquid crystal (LC) cell in which the surfaces are modified with azobenzene polymer layers is shown to be able to align the helix axes homogeneously. The helix axis of a relatively short pitch chiral nematic LC takes the behavior of the macroscopic optic axis so that induced birefringence is achieved. Polarized optical microscopy and transmission ellipsometry were used to elucidate the alignment behavior of the aligned helix axis. It is found that the helix axis aligns in-plane perpendicularly to the propagating direction of the activation light. This is the first example of a stable alignment of helix axes of chiral nematic LCs performed with anisotropic polymer layers.

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We described the photoinduced thermal orientation of the photo-crosslinkable methacrylate copolymer liquid crystal (CPLC) film comprising a photoreactive 6-[4-(2-cinnamoyloxyethoxy) biphenyloxy]hexyl side group and a photoinactive 5-(4-cyanobipheyloxy)heptyl (5CB) side group by the use of lineary polarized ultraviolet (LPUV) light irradiation followed by annealing. The out - of -plane alignment of the mesogenic side groups was observed when the heating rate after the LPUV light exposure was 90℃/min, while the mesogenic groups aligned homogeneously with the direction parallel to the electric vector of the incident LPUV light when the heating rate was 1℃/min.

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In order to simplify the fabrication processed of a Ferroelectric Liquid Crystal Spatial Light Modulator (FLCSLM), we have tried to use a photo-alignment method to aligning FLCs and use a multi-dielectric film structure consisting of different kinds of a Si:H layers as a reflective mirror. The results indicate that, the simplification of the process comparing to the conventional one may be possible.

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A Holographic Polymer Dispersed Liquid Cryslals (HPDLC) device has a periodicaily stratified struclure comprised of the LC and polymer layers. It has been remained an important issue, to reduce the drive voltage to gel low power operation of the display device. The drive voltage of an HPDLC cell was Jowered using a dopant. The dopant has perfluoro alkyl and hydroxyl moieties. The saturation vollage was found to be redueed to half of the voltage required for the HPDLC without the dopant.

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Measurement of the state of light polarization is very important for characterizing optical device. Therefore it is very difficult to measure the state of polarization with the usual method. Purpose of This study is development of real-time optical system for measuring "Stokes Parameter" using a Wedge-Shaped liquid crystal optical device. Result, this device allowed us to measure "Stokes Parameter".

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It has known that the super-resolution using a shadow mask is one of the well-known techniques. However, this method is not widely used due to the appearance of large side-lobes at the focus point. There is a report that a super-resolution spot with reduced side-lobes can be realized using a liquid crystal optical element with two different LC aligned regions. In this study, by using a photo-alignment method with a new LC aligned structure we report the method to simplify the fabrication processes of the same kind of the optical element.

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A novel liquid crystal (LC) cell with stacked electrode structure to obtain large effective path length compared to the millimeter wavelength is proposed for an application to the millimeter wave devices by using the relatively large birefringence of LC materials in the millimeter wavelength region. We prepared the LC cell using metal substrates, and the millimeter wave transmission properties are experimentally and theoretically investigated.

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We propose a novel type liquid crystal (LC) micro optical device using a weak anchoring substrate. The LC cells are prepared using 8-devided hole-patterned electrodes which are coated by alignment films with different azimuthal anchoring energy. When using the weak anchoring substrate, the polarization direction can be controlled by the applying in-plane electric field, and wavelength mdependent properties can be obtained.

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The spatial distributions of phase retardation of a light beam passing through a liquid crystal lens are obtained based on the results of the director orientation simulation. A liquid crystal lens has good optical properties when there is no applied voltage or the voltage exceeds a certain value.

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Dynamic responses of liquid crystal microlenses with difiercnt diameters are analyzed numerically. We show that LC microlens with smaller diameter tend to response to external fields faster. The physical origin is discussed.

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Liquid crystal (LC) microlenses with the stacked electrode structure have large numerical aperture. In this work, we introduce an improved driving method which consists of two steps: that is, i) a large voltage is applied for a short interval, ii) then a desired voltage is applied. It is found that, in tile case of a conventional LC microlens, a reverse-tilt disclination is undesirably generated by introducing the two step driving method. This disclination stably remains in the hole-patterned area and disturbs the improvement of the response properties. On tile other hand, in the case of the LC microlens with the stacked electrode structure, such a reverse-tilt disclination is never seen and the improvement of the response property is successfully achieved by the introduced driving method.

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The infiltration of a nematic liquid crystal into synthetic opal with a three-dimensional periodic structure has been studied. The transmission and reflection spectra of nematic liquid crystal infiltrated opals were measured. The wavelengths of the stop band and the reflection peak shift by the infiltration with a liquid crystal due to the higher refractive index than that of air. Moreover, the stop band and reflection peak are shifted by the change of the refractive index of the liquid crystal infiltrated into opal.

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The alignment characteristics of SiO_2 particles dispersed in a liquid crystal (LC) under an applied electric field have been studied. In the system composed of LC, surfactant and SiO_2 particles, a well-ordered aggregation of particles has been observed under the applied electric field. For this aligned aggregation of particles, phase separation behavior between the LC and surfactant, and electrohydrodynamic flow at the LC/surfactant interface seem to play an important role. This procedure is expected to be one of candidates of the fabrication method of photonic crystal.

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Polymer particles with side-chain mesogens were prepared by suspension polymerization and their liquid-crystalline behavior was studied. Liquid-crystalline monomers were suspended in water by irradiation with ultrasound and were polymerized at temperature where the LC monomers show a nematic phase. We obtained the polymer particles with a diameter of micrometer order. Observation with a polarizing microscope revealed that the polymer particles showed all LC phase and the mesogenic side chains were aligned in the particles.

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