Super Twisted Nematic(STN) - LCD using Spiral Polymer Aligned Nematic(SPAN) liquid crystals has been fabricated by photopolymerization of a chiral monoacrylate in a nematic liquid crystalline host. The Spiral Polymer made of a chiral monoacrylate effects the alignment of a nematic liquid crystalline host and the driving voltage of the LCD is lower than that of the conventional STN - LCD. The pitch of a chiral nematic liquid crystals with a chiral monoacrylate inclines to extend during photopolymerization. The relation of the extended pitch and the chemical structure of a chiral monoacrylate is discussed.

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In slow responding reflective STN-LCDs, frame response reduces contrast ratio. Mult-Line Selection technique(MLS) that suppresses frame response is useful for increasing the contrast ratio in this STN-LCD as well as in case of fast responding transmittive STN-LCDs. MLS is also usefull in colour STN-LCDs using effects of birefringence. We show these usefullness of MLS by computer simulations and testing sampleLCDs.

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The results of simulation of reflective characteristic at the color LCD with reflective multi layer have been discussed in this paper. At this type color LCD, a reflective light wavelength was comparatively narrow in separate R・G・B band, so we could get satisfactorily at displaying color image.

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The reflective type color STN LCD without the use of a backlight, as an alternative of a low power consuming display device, have been receiving increasing attention recently. However, its optical characteristics related to the color purity, which has been developed up to now, fall far behind other display devices. Therefore we have examined the optical design requirements able to display more colors, as well as improve the purity of display color, report here the results.

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Optimization for achieving a black and white representation in reflective STN-LCDs with a single polarizer and phase plates is discussed. It has been clarified analytically that it is possible to realize a good black representation by using two phase plates between a STN cell and a reflector.

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In reflection type LCD, brightness of bright pixels adjacent to dark pixels decreases in some conditions. We named this phenomena "shadow of dark pixels". It's cause is supposed that contrast ratio in light incident direction is not equal to 1. A new method of finding light incident direction with least contrast ratio is devised, and "shadow of dark pixels" is tried to decrease by analyzing polarization state of the light transmitted liquid crystal layer.

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The electro-Optical properties and the allowable deviation of device parameters from an optimally designed value of an achromatic reflective STN-LCD with one polarizer and one retardation film are analyzed and it is found from the results that several sets of solution to be of practical use exist.

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This paper describes parallax free λ/4GH Reflective LCDs, which have λ/4 retardation layer and light diffusing layer inside of the cell. Both layers are made of liquid crystalline polymers freezed thier orientation. This structure enables high reflectance, gray scaling and high resolution.

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The fast-switching and bistable surface-stabilized ferroelectric liquid-crystal(SSFLC) structure has a great potential for application in reflective color liquid-crystal displays. We studied the relation between polarizer axis and tilt angle of SSFLC. We sifted polarizer axis from the long axis of FLC molecule. As a result, we obtained high bright reflective SSFLC displays, such as under 1000 1x, white level is 21.4 cd/m², black level is 1.6 cd/m². This result clarified the possibility of a reflective color SSFLC display.

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Reflective liquid crystal displays(LCDs) attract many interests for its light weight and low power consumption. We propose a new type of reflective LCD mainly comprising a Hybrid-aligned nematic LC-layer, a biaxial-retardation film, a light scattering film and a mirror electrode. This new type of reflective LCD has advantage of high resolution owing to the mirror electrode and wide viewing angle by designing with the same concept of the OCB mode. In this paper, we describe the structure and optical properties of this new reflective LCD.

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Threshold voltage and alignment uniformity variations of liquid crystals within cells were investigated as a function of various organic contaminants present on the alignment layers. The threshold voltage change for cells containing a fluorine liquid crystal material was smaller than that for a cyano liquid crystal material. The extent of the reduction in alignment uniformity depended on the molecular structure of the alignment layers and the attached organic materials. This phenomenon could be explained by their chemical affinity.

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In this paper, the DC offset voltage (V_DC) generated in liquid crystal cells during AC operation is investigated in the case where the composition of the front and rear alignment layer differ. Four different species of polyimides made from two types of acid anhydrides and two types of diamines were used as alignment layers. The relation between the chemical structure of the alignment materials and V_DC is discussed. It was found that V_DC depends on the different alignment layers' polarizability which is related to the oxygen atoms present in the polyimides molecules.

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In the chevron geometry of a smectic phase, making defect free smectic layers is closely related to control the bending direction of layers. It is possible to select this direction by encapsulating liquid crystals in the closed rectilinear space and cooling it under the strong temperature gradient from one end of the rectilinear space toward another end.

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Three layer system of liquid crystal/polyimide oligomer/graphite have been examined by molecular dynamics(MD) simulations as a model interface system of LCD. Liquid crystal molecules were aligned 20° tilted direction with polyimide chains with carbonyl part of polyimide was the main anchoring portion.

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A series of polyimides containing pendant liquid crystalline mesogenic moieties, such as cyanobiphenyl, has been designed, and synthesized. They can easily be processed by spin-coating into LC alignment films. Molecular orientation properties of these alignment films showed fairly different behavior compared to those laterally fused long alkyl side-chain. In order to understand the results, the differences of terminal substituent dipole moments and polyimide conformations have been simulated by the methods of molecular orbital and molecular mechanics calculation techniques.

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The static domain structures of solid state ferroelectrics have been investigated by liquid crystal method. In this method, we tried the direct observation of the dynamic surface state near critical point in Tri-glycine sulfate(TGS).CCH series, which have isotropic, nematic and smectic phases in Tc area of TGS, are used as test liquid crystals. The observations of each phases are reported.

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We discuss on first-wetting transition from partial to complete wetting near a wall in solutions of rigid-rod-like molecules. Based on the Cahn's construction for the free energy of a surface and Flory theory for hard rods, we caluculate the intrefacial tension, the adsorption amounts and the contact angle as a function of temperature and the adsorption energy.

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A simple model is developed to describe the adsorption and the surface ordering on solutions of rigid-rod-like molecules. We here focus on the plalar adsorption of the rigid rods restricted the orientations to two mutually orthogonal directions; two parallel to the surface. When the bulk concentration increases, the adsorbed amount is increased and the adsorption isotherm has a kink at a bulk concentration φ_c where the isotropic-nematis transition(INT) in a surface phase takes plece. Further increasing concentration, the adsorbed amount jumps at the bulk critical concentration φ_IN, where the INT takes places in the bulk phase. For the range of concentrarion φ_c < φ < φ_IN, we find the wetting of an isotropic bulk phase by a nematic surface phase. For various values of the axial ratio of the rigid rods, the solvent conditions and the adsorption energy, we examine the adsorption isotherms and the surface ordering. We also disscuss on the co-occurences between adsorption phenomena and the phase separations of surface phases.

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The mechanism of liquid crystal molecule(5CB) alignment by the polarized UV irradiated photosensitive polymer has been studied by means of FT-IR and UV/vis spectroscopy. The crosslinking reaction of polyvinyl cynnamate(PVC) fairly depends on the temperature of substrate at the time of the polarized UV irradiation. According to the examination of the relation between the crosslinking of PVC and 5CB alignment, the 5CB aligns gradually due to the proceeding of the crosslinking reaction.

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Positive-type polyimide, exposed to linearly polarized deep UV(DUV) light (257 nm), induced nematic liquid crystals' homogeneous alignment with small pre-tilt angle. A two stage exposure was introduced to establish a pre-tilt angle. A tilted alignment mechanism was explained by anisotropic photo-depolymerization of polyimide side chains.

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It is very important to clarify a molecular orientation in a cross section of a liquid crystal cell for understanding of electro-optical properties in LC devices, In this study, a new visualizing method to observe the molecular orientation state in the cross section of the LC cell is proposed and demonstrated by using a UV curable LC material. The molecular orientation state in the cross section of the LC cell. with a slit-patterned electrode structure (a LC cylindrical microlens) is clearly visualized using this procedure.

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The surface of substrate fabricated by using the stripped film method gave the uniform orientation of both nematic director and pre-tilt angle^<1)>. This stripped film surface fabricated by using the alignment layer constructed with three kinds of organic films, Vinylon base film (KURARAY Co.), PVA adhesive agent and Polyimide film (Japan Synthetic Rubber Co.), generated unique characteristics of pre-tilt angle of nematic liquid crystals.

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Orientation of liquid crystalline(LC) molecules depends on the condition of the substrate surface. It has been reported that LC molecules can be aligned uniaxially on a polymer surface prepared by using a dipping coating method from polymer solution without rubbing the surface. This study was aimed to understand the mechanism of molecular alignment caused by the interaction between the surface of polymers and LC molecules. Optical micrographs of LCs in sandwich-typed cells depict that a dip-coated polystyrene(PS) substrate exhibits highly homeotropic orientation as well as a dip-coated poly(vinyl alcohol) (PVA) substrate, whereas a dip-coated polyimide substrate causes LC molecules to align spontaneously parallel to the dipping direction without rubbing treatment. The light scattering measurement, which gives the molecular motion in the LC state, confirms that the PS-coated substrate causes much higher degree of homeotropic alignment than the PVA-coated substrate, while an aminosilane-coated substrate shows almost complete homeotropic alignment.

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We propose the Double-Resolution LED Printer which introduced the liquid crystal light shifter formed of a birefrigent crystal and a liquid crystal element into the LED arrays print head. This method can double the printing resolution for the density of the LED elements assembled on the head. Printing data of a line are divided between odd data and even data. All LEDs alternately illuminate for the odd and even data. In exposure for even data, the liquid crystal light shifter shifts the irradiated position on the photoconductive drum to half distance between each LED elements. Therefore, the printing resolution can double for the density of the LED elements. In this paper, we show the theory of this system and the basic experimental results of light beam shift, and we show the possibility of double-resolution printing.

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A new LC panel structure which enables a really practical ferroelectric LCD is proposed by introducing a thermosetting epoxy "spacer". The new concept of the thermosetting epoxy spacer provides a honeycomb structure in the LC panel, resulting in a tenacious LC panel against mechanical shocks. Thanks to the tenacious panel structure, an FLC display is got rid of the vulnerability in a portable use.

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This paper describes a novel technique to measure both cell gap and twisted angle in TN liquid crystal cells, simultaneously. The cell gap and the twisted angle are determined by measuring retardation of linear birefringence and optical rotation angle which is defined as circular birefringence. This technique is based on an optical heterodyne interferometry with rotating analyzer and two-phase lock-in amplifier. The resolution of this method is verified by using the combination of the Babinet Soleil compensator and half wave plate as the sample. The measurement results of cell gap and twisted angle are compared with predetermined values on manufacturing the cell.

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We have already proposed a method to determine the elastic constant ratio K₃₃/K₁₁; froma linear relationship between capacitance and reciprocal voltage of LC cell in the higher voltage range. In this method, it was found that a small error in determing of the Freedricksz threshold voltage V_c could induce a large error of K₃₃/K₁₁. Therefore, in this paper, we propose a new method to determine V_c by simple curve fitting of capacitance-voltage curve in a low voltage region. Then, applying this value of V_c, K₃₃/K₁₁ can be accurately determined by the previously rerported method mentioned above.

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The photoelectromotive force of nematic liquid crystal and ferroelectric liquid crystal cells with the semiconductor wafer was investigated on a visible radiation. Nematic liquid crystal cells had the high electromotive force compared with ferroelectric liquid crystal cells. The photoelectromotive force of cells with the cell thickness of 25〜50 μm had the lower values. The cells with the thin cell thickness and the dissolution of dyestuffs had the high values of the electromotive force. The photoelectromotive force characteristics indicated the saturation curve on the incident light of 1000 lux.

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We investigated mobile ion effect in LC panels by using MTR-1 ion density measurement system and VHR-1A voltage holding ratio measurement system. We found the clear correlation between ion density and voltage holding ratio. We also found the distribution tendency of the measurement values depend on the location of the LC panels. The distribution of ohmic resistivity values showed no clear correlation between ion density value and voltage holding ratio value. It was also found that ion density increases by decreasing the frequency of the applied triangular wave.

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Conformational and orientational properties of a ferroelectric liquid crystalline molecule with selectively deuterated chiral chain (α-methyl alkyloxy chain) have been studied by ²H-NMR. The spectrum in the SmA and SmC phases consists of a superposition of well resolved quadrupole doublets, while that in a low-temperature Swχ phase consists of a two-fold flip-flop pattern. The observed quadrupole splitting profiles are analyzed using molecular orbital calculation data to determine the average conformation and orientation of the chiral terminal chain. This is the first example of experimental conformational analysis of FLC molecules using ²H-NMR technique. The results obtained here should apply to all FLC molecules with α-methyl alkyloxy chain.

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Electric Pulse Switching Response of Ferro- and Antiferroelectric Liquid Crystals is experimentalily investigated in detail and the very short time transient currents(μ sec) depending extraordinarily on the load resistance are found out in AFLC. This remarkable phenomena is discussed in relation to the characteristic structures and the different origins of the spontaneous polarization between FLC and AFLC.

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Time domain spectroscopy(TDS) is used to obtain the signal information over a wide frequency range (DC〜10GHz) in only a fraction of a second by making the measurement not in the frequency domain but in the time domain. We applied TDS method the test observations of the critical rotational slowing down phenomenon in ferroelectric liquid crystals at the phase transition by using narrow pulse laser.

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Ferroelectric liquid crystals with a helical structure have two kinds of fluctuational modes : the amplitudon mode and the phason mode. We have observed the phason mode by means of the quasielastic light scattering technique and the linear dielectric relaxation spectroscopy and compared the correlation time and the relaxation time obtained from both the method to check the equivalence of the two methods.

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In order to investigate the details of the molecular flucluation behavior in the SmC_A^* and SmC_α^* phases, we have carried out dielectric and electro-optical measurements. The samples used were (R)-MHPOBC and (S)-TFMHPOBC. In SmC_A^*, the relaxation process of the phase mode which is corresponding to the fluctuation of the helix was easily observed through the electro-optical responses. The frequency of the optical signal due to the antiferroelectric phase mode is twice as high as that of applied ac fields, because the distortion of the helix is caused by a dielectric anisotropy. By applying a dc bias field, the antiferroelectric phase mode, which has the same frequency as the applied ac field, is also observed similarly.

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We have directly observed the relaxation time of molecular rotation about the long molecular axis of SmA inferroelectric and antiferroelectric liquid crystals by means of transient optical Kerr method. We found that the relaxation time is about 20 picosecond in SmA and the rotational motion does not critically slow down in SmA as the temperature approaches the SmA-SmC^* transition. Our experimental results are inconsistent with Lallane et al.'s reports[Phys. Rev. A, 44 (1991) 6632].

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Complex dielectric constant of an antiferroelectric liquid crystal 4-(1-methylhepthyloxycarbonyl)3-fluorophenyl 4'-dodecylbiphenyl-4-carboxylate(MHFPDBC) was measured in a frequency range between 10^-2 Hz and 10⁷ Hz. Two characteristic relaxation modes of relaxation frequency about 10^-2 Hz and 10² Hz were confirmed in ferrielectric phases, SmC_γ^* and FI. A Slowly time-dependent of the dielectric constant was also observed in ferrielectric phases. The phenomenon is concerned with the disordered structure in ferrielectric phases, and the slow time dependence of dielectric constant was thought to be a changing process from a metastable to the stable state of SmC_γ^* phase.

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We have prepared MHPOBC (4-(1-methylheptyloxycarbonyl) phenyl 4'-octylbiphenyl-4-carboxylate) and its homologues with various 'lateral' substituents at the chiral center in order to realize the variaty of AFLC compounds. The antiferroelectricC phase (SmC_A^*) was observed for the homologous series except the pentyl homologue. The miscibility studies of the homologue and 8OSI^* (FLC) were carried out. The mixture exhibited the SmC_A^* phase, indicating that the chirality of the system may induce the antiferroelectricordering.

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We have theoretically studied the electro-optic effect and third-order nonlinear dielectric response in antiferroelectric liquid crystals on the basis of phenomenological equations of motion. It has been found that the antiferroelectric soft and Goldstone modes can be excited by an electric field, though they respond to the square of the field but not to the field itself, and they modulate the dielectric constant both for the visible light and low frequencies, contributing to the electro-optic effect and the third-order nonlinear dielectric response, respectively.

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The third-order dielectric constant and the electro-optic effect were measured in antiferroelectric liquid crystals. The third-order dielectric relaxation due to the antiferroelectric Goldstone mode was observed, which was Debye-type, as was theoretically expected by Orihara and Ishibashi. The temperature dependence of the relaxation frequency was also obtained. In the electro-optic measurement of TFMHPOBC, it was found that the intensity vanishes at a certain temperature, which depends on the optical purity. This result will be discussed on the basis of a phenomenological theory proposed by Orihara and Ishibashi.

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The dielectric biaxiality (∂ε) and the dielectric anisotropy (Δε) were measured for a binary system with FLC mixtures in order to investigate the relationship between ∂ε(Δε) and τ-Vmin property. It was found that the dielectric biaxiality (∂ε) exhibited non-linear behavior against the component ratio of binary liquid crystal mixtures while the dielectric anisotropy(Δε) linearly changed. The τ-Vmin measurement were carried out using the ferroelectric liquid crystal(FLC) mixtures with various dielectric biaxiality and dielectric anisotropy. The voltage minimum was found to have a good correlation with the dielectric biaxiality.

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The τ-Vmin of ferroelectric liquid crystal(FLC) material with negative dielectric anisotropy is an attractive mode because of their properties such as high contrast, fast line address time and wide operating temperature range. In this study, we investigated the possibility of the gray scale for the multi thickness cells using the τ-Vmin mode. The deferent thickness of FLC layer induced a change in the τ-Vmin characteristics. A combination of two areas with different thickness gave a possibility of 3 or 4 gray levels.

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Two type of electrooptic effects, a transient scattering mode(TSM) at the instant of polarity reversal of applied voltage and a deformation of helicoidal structure(DHS) effect upon applying stepwise voltage in the chiral smectic C (Sm C^*) phase of ferroelectric liquid crystalline polymer(FLCP) have been studied. The response times of TSM and DHS effect become shorter with increasing applied field and temperature. A stripe pattern parallel to the smectic layer has been observed at the instant of polarity reversal. This stripe pattern has been maintained after removal of pulse voltage. New electrooptic effects utilizing the characteristics of FLCP has been discussed.

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Extremely thin free-standing ferroelectric and polymeric ferroelectric liquid crystal films with the thicknesses in the range of several tens and hundreds nm have been fabricated. successfully. The structure and electrooptical properties have been studied by ellipsometric measurements. Both SmA and SmC^* phases still exist even in such ultra thin films. Electrooptical measurement with crossed polarizers was carried out. From the results of the electrooptical measurement, the phenomenon that disturbs the electrooptical response was found in the higher temperature range of the SmC^* phase.

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Well-aligned thin films of polymeric ferroelectric liquid crystal have been prepared by means of a spin-coating method. Several types of electrooptical effects in these films have been measured. When the polarity of the applied field was reversed in the SmC^* phase, director waves which start from the electrode edges and propagate to the center of the active area were observed with the polarizing optical microscope in the spin-coated film. In order to investigate this director wave, electrooptical effects with crossed polarizers were studied. The characteristics of their effects in spin-coated polymeric ferroelectric liquid crystal film with a free surface have been discussed in comparison with those of conventional sandwich cells.

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The dielectrical and phase transition properties of some ferroelectric liquid crystals with different terminal groups in their molecular structures have been studied. The phase series were markedly dependent on the terminal structures. Dielectric properties of the mixture of these chiral smectic and non-chiral smectic liquid crystals also showed marked dependence on the composition and concentration of the mixture. That is, the sign inversion of spontaneous polarization was found in the binary mixture of chiral smectic and non-chiral smectic liquid crystals. The inversion temperature was sensitive to the concentration of ferroelectric liquid crystal. In the cell with surface treatments, unsymmetrical response was observed upon applying a stepwise field except at the temperature showing the sign inversion.

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In the composite prepared with conducting polymeric liquid crystal, poly[5-(p-(trans-4'-n-octylcyclohexyl)phenoxy)-1-pentyne] (PPCH803A) and ferroelectric liquid crystal, (R)-4'-(1-methoxycarbonyl-1-ethoxy) phenyl 4-[4-n-octyloxy) phenyl] benzoate (1MC1EPOPB), novel electrical and optical properties have been observed. Dielectric constant of the composite is extremely large in the smectic C^* phase. Spontaneous polarization of the composite appears at Tc and becomes larger with decreasing temperature. The response time of electro-optical effects in the composite is shorter than that in 1MC1EPOPB.

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We have studied second harmonic generation(SHG) in both crystalline and nematic phases of aromatic copolyester of 4-hydroxy benzoic acid(HBA) and 6-hydroxy-2-naphthoic acid(HNA). The SH profiles as a function of incident or SH polarizations are well similated under the model of C₃ symmetry with a mirror plane rotationally disordered about the molecular long axis. This is the first polar, probably ferroelectric liquid crystal.

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The linear and nonlinear dielectric constants and electroclinic coefficient of some antiferroelectric liquid crystals are simultaneously measured in various smectic phases, SmA, SmC_α^* and SmC_A^*. The critical behavior in the SmA phase near the SmA-SmC_α^* or SmA-SmC_A^* phase transition is well describable by the phenomenological theory of Landau type which is proved to be applicable to the SmA-SmC^* phase transition. We can calculate the phenomenological coefficient concerning to the ferroelectric order parameter. It is found that the third-order nonlinear dielectric constant in the SmC_A^* phase shows a positive sign which is in contrast with a negative sign in the SmC^* phase due to the Goldstone mode.

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Side-chain liquid-crystalline polysiloxanes with cyanobiphenyl mesogenic group, Poly [6- (4-cyanobiphenyl-4'-oxy) -hexylmetylsiloxane](PCS), were prepared with different degree of substitution, and the liquid crystallization and structures of them were investigated. All samples showed smectic A(SA) phase. Glass transition and clearing temperatueres increased with increasing degree of substitution. The rates of liquid crystallization increased, and the layer structures of SA indecated higher long-range order with degree of substitution.

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When a side-chain liquid crystalline Polyailoxane containing a cyanobiphenyl mesogen group was melt-crystallized from the isotropic melt in the external electric fields of alternating current, the needle-like and batonnet textures formed in smectic phase aligned along the electric fields. The sample showed an oriented X-ray scattering pattern; the periodic small angle reflections associated with the smectic layer structure were observed in the direction of the field. Consequently, mesogenic cyanobiphenyl groups were packed perpendicular to the direction of growth in the needle-like liquid crystalline texture.

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