No abstract

The influence of hardness and topology of substrate surface on the pretilt angle were investigated for a slightly tilted homeotropic alignment achieved by the rubbing technique. On a soft surface, the grooves are produced which align in the same direction as the rubbing direction while the liquid crystal molecules tilt in the direction opposite to the rubbing direction. On a hard surface, no grooves are observed and the molecules tilt in the same direction as the rubbing direction. These results were applied to the fabrication of a two-domain vertically aligned nematic liquid crystal display.

The studies on the fundamental requirements for realization of a multiplexed ferroelectric liquid crystal (FLC) display have been presented as follows:(1) The new classes of 2,5-diphenylpyrimidine FLCs are useful as a blending component for broadening the Sc* temperature range and improving the switching response time.(2) A FLC material with the Iso-N*-SA-SC* phase transition sequence as well as the long Sc* and N* helical pitches i s required to achieve the homogeneous alignment in a Sc* phase.(3) Among the FLC cells with various alignment layers, the PI/PI coated cell exhibits the symmetric and steep bistability threshold behavior.( 4 ) The parameters to evaluate the multiplexing capability of a FLC cell are introduced and applied to select a suitable combination of alignment layers for highly multiplexing.(5) The parameters are also used to evaluate a favorable drive method among the drive schemes proposed so far for multiplexing a FLC cell.On the basis of the above studies, a multicolor ferroelectric LCD with 639x400 pixels in an A4 size has been developed.

Polymeric films were deposited onto a glass plate by RF glow-discharge polymerization. Monomer gases tried were ethylene, allylamine and tetrafluoroethylene. The effects of such surface properties as the contact angle, surface energy, and those measured by FT-IR or XPS on liquid crystal alignment were studied. It is shown that liquid crystal alignment can be controlled systematically by plasma copolymerization of different monomers or plasma treatment after polymerization which can vary surface properties continuously.

Viewing angle characteristics of a twisted nematic (TN) liquid-crystal display (LCD) have been improved by inserting a planar aligned cholesteric liquid crystal compensating layer between the TN cell and a polarizer. Dependencies of the electro-optical characteristics of the novel LCD on the retardation, ratio of thickness to the pitch (dc/p) and twist-sense in the cholesteric layer are discussed. A thin-film transistor addressed LCD with a wide viewing angle has been developed based on this novel cell construction and its display performance is reported.