Provided is a liquid crystal composition, which comprises a component prepared from one or more compounds selected from a general formula I; and a component prepared from one or more compounds selected from a general formula II. The liquid crystal composition has the characteristics of low viscosity, high reliability, appropriate optical anisotropy, and appropriate dielectric anisotropy, and is applicable to liquid crystal display devices. ##STR00001##

Provided is a compound represented by formula (1) described below.

##STR00001##

In formula (1), a and b are independently 0, 1 or 2, and expressions: 0a+b3 hold, ring A.sup.1, ring A.sup.2, ring A.sup.3 and ring A.sup.4 are independently 1,4-cyclohexylene, for example, Z.sup.1, Z.sup.2, Z.sup.3, Z.sup.4 and Z.sup.3 are independently a single bond, alkylene having 1 to 10 carbons, or the like, Sp.sup.1 and Sp.sup.2 are independently a single bond, alkylene having 1 to 10 carbons, or the like, and P.sup.1 and P.sup.2 are independently a specific polymerizable group.

Disclosed are a liquid crystal composition and a liquid crystal display device. The liquid crystal composition comprises at least one compound of general formula I, at least one compound of general formula II, at least one compound of general formula III, and at least one compound of general formula IV. By compounding the four compounds, the composition can have advantages of a wide temperature range of nematic phase, a low viscosity and a low threshold voltage, and the liquid crystal display element can have a short response time and great power saving performance.

The invention relates to a polymerisable LC medium with flat, negative or positive optical dispersion, a polymer film with flat, negative or positive optical dispersion obtainable from such a material, and the use of the polymerisable LC medium and polymer film in optical, electro optical, electronic, semiconducting or luminescent components or devices.

The subject is to provide liquid crystal display device having a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio, a long service life and a small flicker rate. The liquid crystal display device having a liquid crystal alignment film formed on the opposing surfaces of a pair of substrates, and a liquid crystal composition therebetween, wherein the liquid crystal alignment film includes a polymer derived from a polyamic acid having a photodegradable group, and the liquid crystal composition includes at least one compound represented by formula (1) as a first component: ##STR00001## R.sup.1 is alkyl having 1 to 12 carbons or the like; ring A is 1,4-cyclohexylene, 1,4-phenylene or the like; Z.sup.1 is a single bond or the like; X.sup.1 and X.sup.2 are hydrogen or fluorine; Y.sup.1 is fluorine or the like; and a is 1, 2, 3 or 4.

Provided are a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy, large negative dielectric anisotropy, large specific resistance, high stability to ultraviolet light and high stability to heat, or has a suitable balance regarding at least two of the characteristics; and an AM device having characteristics such as a short response time, a large voltage holding ratio, low threshold voltage, a large contrast ratio and a long service life. The liquid crystal composition may contain a specific compound having large negative dielectric anisotropy as a first component, a specific compound having high maximum temperature as a second component, a specific compound having negative dielectric anisotropy as a third component, or a specific compound having a polymerizable group as an additive component.

A liquid crystal composition that satisfies at least one of characteristics such as a high maximum temperature, a low minimum temperature, a wide temperature range of a liquid crystal phase, a small viscosity, a large optical anisotropy, a large positive or negative dielectric anisotropy, a large specific resistance, a high stability to light, a high stability to heat and a large elastic constant or that is suitably balanced between at least two of these characteristics. The means is use of a liquid crystal composition that includes a specific compound having a high maximum temperature or a small viscosity as a first component, and that may include a specific compound having a large positive dielectric anisotropy as a second component, or a specific compound having a large negative dielectric anisotropy as a third component or a specific compound having a polymerizable group as a first additive.

A liquid crystal composition that satisfies at least one of characteristics such as a high maximum temperature, a low minimum temperature, a small viscosity, a suitable optical anisotropy and a large negative dielectric anisotropy, or that has a suitable balance between at least two of these characteristics, and an AM device including this composition. The nematic liquid crystal composition includes a specific compound having a large negative dielectric anisotropy as a first component and a specific compound having a small viscosity as a second component, and may include a specific compound having a negative dielectric anisotropy as a third component, and a specific compound having a high maximum temperature or a small viscosity as a fourth component, or a specific compound having a polymerizable group as an additive.

The present application relates to mixtures which have liquid-crystalline properties. The application furthermore relates to the use of the mixtures in devices which regulate the transmission of light through an area element.

The purpose of the invention is to control, by using a colorless alignment control monomer, the alignment of liquid crystal molecules of a liquid crystal display element that does not include an alignment film, and to provide a liquid crystal composition with which the colorless alignment control monomer exhibits excellent compatibility. The invention uses a liquid crystal display element that comprises an alignment control monomer including an aromatic ester that undergoes photo-Fries rearrangement by light irradiation, and that employs a liquid crystal composition having a positive dielectric anisotropy. The invention also uses the liquid crystal composition.