Masaya Mizunuma

Alignment and Electro-Optic Properties of SSFLC Cells Aligned by Obliquely Evaporated SiO Films

Abstract Alignment and electro-optic properties of SSFLC cells aligned by 85° obliquely evaporated SiO films are investigated. The vacuum condition of the SiO evaporation was found to have a great effect on the alignment. The SiO film evaporated in a high vacuum gives a poly-domain alignment which is reformable into a mono-domain by the application of a strong electric field. The cell with the reformed alignment shows an almost perfect memory and a high contrast in a specific temperature range, which suggests that the cell is aligned in the so-called “uniform” state. A cell with the SiO film by low vacuum evaporation shows an imperfect memory and a very low contrast. The alignment of this cell is confirmed to be in the “twisted” state. The strong electric field gives no influence on the alignment of this cell. Possible relation between the obtained alignment and the observed SiO columnar structure is discussed.

Effects of polymer matrix on electro-optic properties of liquid crystals mixed with polymer

The presence of hysteresis in transmittance-voltage characteristics of liquid crystal mixed with polymer (LCMP) has been the main cause for the residual image of LCMP display devices. This hysteresis is regarded to originate in the interaction between liquid crystal material and matrix polymer. The molecular motion of the matrix polymer of LCMP is varied systematically by changing the monomer and photo-initiator content. The hysteresis of LCMP decreases as the elastic modulus of matrix polymer decreases. It has been found quite effective to lower the elastic modulus of matrix polymer in reducing the hysteresis of LCMP.

Light Scattering Properties of Polymer Dispersed Liquid Crystals

Abstract The Stein-Rhodes Model (SR model) which explains light scattering by anisotropic spheres is applied to the light scattering phenomenon in Polymer Dispersed Liquid Crystals (PDLC). Comparison of Hv light scattering capability obtained by both the experiment and the theoretical model reveals that, especially in a high temperature region, the experiment provides stronger light scattering intensities than the theoretical model. Observation of PDLC under a polarized microscope shows that the region in which a liquid crystal is oriented expands with the increase of temperature. We assume from these results that the temperature dependence of the birefringence of a liquid crystal droplet is smaller than that of a bulk liquid crystal, which is mainly caused by the difference of liquid crystal orientation. For applying the SR model to PDLC, we must take into account the temperature dependence of liquid crystal orientation in the droplets.

Uniformly aligned ferroelectric liquid crystal cell applied to a light valve

Abstract A ferroelectric liquid crystal light valve (FLCLV) for laser pulse recording is studied. We have fabricated a FLCLV that is equipped with a SiO obliquely evaporated film as a liquid crystal alignment layer and a metal-insulator-semiconductor (MIS) photodiode as a photoconductive layer. When the cell gap is about 3um, the liquid crystal alignment shows scale like defects. When the cell gap is reduced to 2um, that scale like defects disappear. High resolution capability of 50 lp/mm is obtained using diode laser, the power of which is merely 20pJ, in this cell.

Wide-viewing-angle LCD controlled by a lateral electric field

With the aim of developing a wide viewing angle liquid crystal display (LCD), we are trying to apply in-plane switching (IPS) mode, in which liquid crystal molecules are switched by a lateral electric field, to TFT-LCD. We have studied the detailed relationship between the electro- optical properties and the various panel conditions. From these results, we specified the panel conditions, such as plus 10.4 dielectric anisotropy of liquid crystal material, 3.5 micrometer panel gap and 8 micrometer electrode spacing, to fabricate the IPS mode TFT panel. We have achieved the IPS mode TFT color panel that possessed not only wide viewing angle characteristics over 80 degrees with no reversed image but also a fast response time 50 ms, a low driving voltage compatible with ordinary twisted nematic (TN) mode TFT panel and a fine white balance, (x,y) equals 0.32, 0.34).