The invention relates to bimesogenic compounds of formula I

##STR00001##

wherein R.sup.11, R.sup.12, MG.sup.11, MG.sup.12, X.sup.11, X.sup.12 and Sp.sup.1 have the meaning given in claim 1, to the use of bimesogenic compounds of formula I in liquid crystal media and particular to flexoelectric liquid crystal devices comprising a liquid crystal medium according to the present invention.

Provided is a liquid crystal composition satisfying at least one or having suitable balance regarding at least two of characteristics such as high maximum or low minimum temperature of a nematic phase, large optical anisotropy, large positive dielectric anisotropy and high stability to ultraviolet light, and a liquid crystal display device including such a composition, particularly an encapsulated liquid crystal display device, and a liquid crystal display device serving as a constituent of 3D lenses. The liquid crystal composition contains a specific compound having large optical anisotropy as a first component, and a specific compound having large optical anisotropy and large positive dielectric anisotropy as a second component; a specific compound having large positive dielectric anisotropy as a third component; and a specific compound having large optical anisotropy and further having high maximum or low minimum temperature as a fourth component, and the liquid crystal display device includes the composition.

The present invention relates to a liquid crystal display device including a specific liquid crystal composition and a sealant in which a cured product of a specific curable resin composition is used. The present invention provides a liquid crystal display device which prevents a decrease in the voltage holding ratio (VHR) of the liquid crystal layer and which enables elimination of problematic defective display such as voids, uneven alignment, and screen burn-in. Since the liquid crystal display device of the present invention prevents a decrease in the voltage holding ratio (VHR) of the liquid crystal layer and enables a reduction in defective display such as uneven alignment and screen burn-in, it is particularly useful for active-matrix liquid crystal display devices of a VA mode and PSVA mode and can be applied to liquid crystal display apparatuses such as liquid crystal TVs, monitors, mobile phones, and smartphones.

The present invention relates to a liquid crystal display device including a specific liquid crystal composition and a sealant in which a cured product of a specific curable resin composition is used. The present invention provides a liquid crystal display device which prevents a decrease in the voltage holding ratio (VHR) of the liquid crystal layer and which enables elimination of problematic defective display such as voids, uneven alignment, and screen burn-in. Since the liquid crystal display device of the present invention prevents a decrease in the voltage holding ratio (VHR) of the liquid crystal layer and enables a reduction in defective display such as uneven alignment and screen burn-in, it is particularly useful for active-matrix liquid crystal display devices of a VA mode and PSVA mode and can be applied to liquid crystal display apparatuses such as liquid crystal TVs, monitors, mobile phones, and smartphones.

The invention relates to liquid-crystalline mixtures comprising at least one compound of the formula I, ##STR00001##
in which
X, L.sup.1, L.sup.2, L.sup.3, L.sup.4 and alkenyl have the meanings indicated in claim 1,
in order to increase the pretilt at the polyimide surface,
and to
liquid-crystalline media comprising one or more compounds of the formula I in electro-optical liquid-crystal displays and in LC lenses.

The invention relates to liquid-crystalline mixtures comprising at least one compound of the formula I, ##STR00001##
in which
X, L.sup.1, L.sup.2, L.sup.3, L.sup.4 and alkenyl have the meanings indicated in claim 1,
in order to increase the pretilt at the polyimide surface,
and to
liquid-crystalline media comprising one or more compounds of the formula I in electro-optical liquid-crystal displays and in LC lenses.

Provided is a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature, a low minimum temperature, small viscosity, large optical anisotropy and large dielectric anisotropy, or has a suitable balance regarding at least two of the characteristics, and an AM device including the composition. The liquid crystal composition may contain a specific compound having large negative dielectric anisotropy as a first component, a specific compound having a high maximum temperature or small viscosity 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.

The problem to be solved by the present invention is to provide: a liquid crystal composition suitable for a liquid crystal display element which hardly generates drop marks in production without worsening various characteristics thereof as liquid crystal display elements such as dielectric anisotropy, viscosity, nematic phase upper limit temperature, low-temperature nematic phase stability, y.sub.1 and others, and also burn-in characteristics of display elements, and which realizes a stable discharge amount of a liquid crystal material in an ODF process, and to provide a liquid crystal display element using the composition. The purpose of the present invention is to provide a liquid crystal composition provided with photosensitizing properties as the entire composition where a polymerizable monomer is combined with specific liquid crystal compounds.

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.

There is provided a liquid crystal composition containing at least one compound represented by General Formula (a). There is also provided a liquid crystal display device using such a liquid crystal composition. The liquid crystal composition of the present invention has the following properties without suffering reductions in refractive index anisotropy (Δn) and nematic phase-isotropic liquid phase transition temperature (T.sub.ni): sufficiently low viscosity (η), sufficiently low rotational viscosity (γ.sub.1), a large elastic constant (K.sub.33), a high voltage holding ratio after UV exposure (VHR (UV)), and a negative dielectric anisotropy (Δ∈) with a large absolute value. A liquid crystal display device of, for example, a VA type that uses such a liquid crystal composition has a high response speed and excellent display quality with defective display being eliminated or reduced.

##STR00001##