The invention is to provide a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of the nematic phase, a small viscosity, a suitable optical anisotropy, a large negative dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light and a high stability to heat, or having a suitable balance regarding at least two of the characteristics; and is to provide an AM device having a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth; wherein the liquid crystal composition includes a specific compound having a large negative dielectric anisotropy and a low minimum temperature as a first component, a specific compound having a small viscosity or a large maximum temperature as a second component and a specific compound having a polymerizable group as a third component, and a liquid crystal display device contains the composition.

The present invention relates to a liquid-crystal medium which comprises one or more compounds each of formulae I and II ##STR00001##
in which the occurring groups and parameters have the meanings given in claim 1.

The present invention relates to azo dye of formula I ##STR00001##
defined in claim 1, to a liquid crystalline medium comprising said azo dye, the use of said medium for optical, electrooptical and electronic purposes, in particular in devices for regulating the passage of energy from an outside space into an inside space, for example in windows. The invention further relates to a device containing the liquid crystalline medium according to the invention.

The present invention relates to azo dye of formula I

##STR00001##

defined in claim 1, to a liquid crystalline medium comprising said azo dye, the use of said medium for optical, electrooptical and electronic purposes, in particular in devices for regulating the passage of energy from an outside space into an inside space, for example in windows. The invention further relates to a device containing the liquid crystalline medium according to the invention.

The present invention relates to compositions comprising a combination of benzothiadiazole and thiadiazoloquinoxaline derivatives, to liquid-crystalline media containing the compositions, and to the use of the compositions and the media in optical, electronic and electro-optical devices, in particular in devices for regulating the passage of energy from an outside space into an inside space, for example in switchable windows.

A LC lens and a liquid-crystal medium used in said LC lens, wherein the medium contains one or more compounds of each of formulae I and II ##STR00001##

A liquid crystal composition includes at least one compound of general formula I, at least one compound of general formula II and at least one compound of general formula III. The liquid crystal composition has a higher optical anisotropy, the relatively large elastic constants K.sub.11 and K.sub.33 while maintaining a relatively high clearing point, an appropriate dielectric anisotropy and a better low-temperature intersolubility. A liquid crystal display device which includes the liquid crystal composition has advantages of a fast response, a high contrast and a wide temperature range, thereby having a good display effect and a large range of applicability. ##STR00001##

A liquid-crystalline medium which comprises at least one compound selected from the group of compounds of the formulae IA to IH,

##STR00001##

in which Z.sup.1 denotes a single bond, —CH.sub.2CH.sub.2—, —CH═CH—, —CH.sub.2O—, —OCH.sub.2—, —CF.sub.2O—, —OCF.sub.2—, —COO—, —OCO—, —C.sub.2F.sub.4—, —(CH.sub.2).sub.4—, —CHFCHF—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —C≡C—, —CF═CF—, —CH═CHCHO— or —CH.sub.2CF.sub.2O—,
and the use thereof for an active-matrix display, in particular based on the VA, PSA, PS-VA, PALC, FFS, PS-FFS, SA-VA, PS-IPS or IPS effect.

A positive dielectric anisotropic liquid crystal composition includes one or more compounds of formula I and one or more compounds of formula II: ##STR00001##
wherein R1 represents cyclopropyl, cyclobutyl or cyclopentyl, R2, R3 and R4 are as defined in the specification, and a liquid crystal display device. The liquid crystal composition has positive dielectric properties, a high charge retention ratio, a low rotary viscosity, a fast response time, and especially a high transmittance, and is suitable for manufacturing a TFT-LCD with a high transmittance and a fast response.

A polar compound has a high chemical stability, high ability to align liquid crystal molecules and high solubility in a liquid crystal composition, and causes no decrease of liquid crystallinity of the liquid crystal composition, a liquid crystal composition contains the compound, and a liquid crystal display device includes the composition. The compound is represented by formula (1), the composition contains the compound, and the liquid crystal display device uses the composition. ##STR00001## In formula (1), R.sup.1 is alkyl having 3 to 15 carbons, alkenyl having 4 to 15 carbons or the like; a is an integer from 2 to 12; and R.sup.2 is a group represented by formula (1a), formula (1b) or formula (1c). ##STR00002## In the formulas, S.sup.1 and S.sup.2 are independently a single bond, alkylene having 1 to 10 carbons; S.sup.3 is >CH— or >N—; S.sup.4 is >C< or >Si<; and X.sup.1 is —OH, —NH.sub.2 or the like.