Hitachi, Ltd.

Tadao Nakata

Akio Mukoh

Hisao Yokokura

Susumu Era

Teruo Kitamura

Kishiro Iwasaki

Yasuhiko Kando

Yasuo Hanawa

Katsumi Kondo

Toshikazu Narahara

Masato Isogai

Shunichi Numata

Hidetoshi Abe

Kooji Fujisaki

A liquid crystal display element comprising a pair of substrates, a pair of electrodes provided on the respective substrates, at least one of which is transparent and a liquid crystal layer disposed between said substrates, the liquid crystal layer comprising a nematic liquid crystal, which exhibits a positive dielectric constant anisotropy and contains an optically active substance, the liquid crystal moleccule orientation direction in the liquid crystal layer is twisted in the range of 200.degree. to 250.degree. from the one substrate surface toward the other substrate surface so as to form a helical structure therein. A polyimide orientation film is provided between the electrodes and the liquid crystal layer. The polyimide orientation film is one made of a polyimide prepared by reacting a diamine compound having a long-chain hydrocarbon group or a diamine compound having a trifluoromethyl group with a tetracarboxylic dianhydride and causes a pretilt angle of at least 3.degree. relative to the nematic liquid crystal molecules. The liquid crystal display element of the present invention is free from a scattering domain.

Liquid crystal polyimide alignment free of scattering domains

The element comprises a pair of transparent substrates, a pair of light-transmitting electrodes each provided on the respective substrates, a ferroelectric liquid crystal layer disposed between the pair of substrates and orientation control films for the molecules of the ferroelectric liquid crystal provided between the electrodes and the ferroelectric liquid crystal layer. The orientation control film controls a tile angle of a biphenyle series nematic liquid crystal having biphenyl ring system below 1.5.degree. and causes a uniform molecule orientation characteristic and a memory property for the ferroelectric liquid crystal element of smectic C* liquid crystal and having a liquid crystal layer thickness of even more than 4 .mu.m.

Ferroelectric liquid crystal element with particular alignment film and

A liquid crystal compound of the formula: R.sub.2 --X.sub.1 --Y.sub.1 --C(O)S--Y.sub.2 --Z, wherein R.sub.2 is preferably C.sub.7-14 alkyl; X.sub.1 is --COO-- or --OCO; ##STR1## and Z is --NO.sub.2 or --CN, shows a smectic phase, is large in positive delectric anisotropy and can give a liquid crystal composition suitable for use in a thermal address display device.

Liquid crystal compound and liquid crystal composition including the same

The present liquid crystal compounds are novel ester-type compounds showing a smectic liquid crystal phase and being capable of increasing a dielectric constant anisotropy, represented by the following general formula: R--X.sub.1 --Y.sub.1 --X.sub.2 --Y.sub.2 --NO.sub.2, wherein R is an alkyl group; X.sub.1 and X.sub.2 are the same or different from each other and are group --COO-- and --OOC--, and when X.sub.1 is group --COO--, ##STR1## The present liquid composition contains the novel compound, and the present liquid crystal display device uses the liquid crystal composition for utilizing the characteristics of the novel compound. Particularly, the present liquid crystal display device is a thermally addressed display device.

Liquid-crystal compound, liquid crystal composition and liquid crystal

Orientation control films are coated on a pair of transparent substrates on the side contiguous to the ferroelectric liquid crystal layer and rubbed for aligning molecules thereof. The films are made of a polyimide polymer prepared by ring closure by heating and dehydrating of a polyamic acid which is synthesized by condensing, for example, pyromellitic dianhydride with 4,4'-diaminoterphenyl. A contrast ratio of the ferroelectric liquid crystal element is improved while keeping a high response characteristic of the ferroelectric liquid crystal materials.

Ferroelectric liquid crystal cell with rubbed polyimide alignment layer

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Katsuta, Japan

Tadao Nakata