A liquid crystal compound comprising a specific compound having a positive dielectric anisotropy as the first component, and a specific compound having a low viscosity as a second component. Further, the liquid crystal compound may contain a specific compound having a positive dielectric anisotropy as the third component, a specific compound having a maximum temperature or a low viscosity as the fourth component, or a specific compound having a negative dielectric anisotropy as the fifth component.

A liquid crystal composition includes a polymerizable compound (or polymer) and a polar compound, where the homeotropic alignment of liquid crystal molecules can be achieved by the action of these compounds, and a liquid crystal display device includes such a composition. A nematic liquid crystal composition has positive dielectric anisotropy and includes a polymerizable compound as a first additive and a polar compound as a second additive, and the composition may include a specific liquid crystal compound having a large positive dielectric anisotropy and a specific liquid crystal compound having a high maximum temperature or a small viscosity, and a liquid crystal display device includes such a composition.

The present invention provides a liquid crystal composition comprising: at least one compound of general Formula I; at least one compound of general Formula II; at least one compound of general Formula M and at least one compound of general Formula N. The present invention also provides a liquid crystal display device comprising the liquid crystal composition. The liquid crystal composition provided in the present invention has a higher optical anisotropy, a higher clearing point, a higher dielectric anisotropy, a high transmittance and a larger average elastic constant. When the liquid crystal composition is used in the IPS liquid crystal display device, the transmittance of the display device can be effectively improved, so that the display device has a good display performance while also having good energy-saving and environment-friendly characteristics.

##STR00001##

A liquid crystal composition includes at least one compound of general formula I and at least one compound selected from a group consisting of the compounds of general formula II-1 and general formula II-2. The liquid crystal composition provided by the present invention has suitable optical anisotropy, high clearing point, high elastic constants K.sub.11 and K.sub.33, and relatively low dielectric anisotropy. When the liquid crystal composition is applied to a liquid crystal display device, the liquid crystal display device may have better weather resistance and higher contrast ratio.

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A liquid-crystalline medium containing one or more compounds of formula IA,

##STR00001##

and the use thereof in an active-matrix display, in particular in a VA, IPS, U-IPS, FFS, UB-FFS, SA-VA, SA-FFS, PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS, PS-posi-VA, PS-TN, polymer stabilised SA-VA or polymer stabilised SA-FFS display.

Shown are a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, low viscosity, suitable optical anisotropy and large negative dielectric anisotropy, or having a suitable balance regarding at least two of the characteristics, and an AM device including the composition. The liquid crystal composition contains a specific compound having large negative dielectric anisotropy as a first component, and a specific compound having low viscosity as a second component, and may contain a specific compound having negative dielectric anisotropy as a third component, a specific compound having high maximum temperature or low viscosity as a fourth component, or a specific compound having a polymerizable group as an additive.

The present invention relates to a liquid crystal (LC) medium comprising polymerisable compounds, to a process for its preparation, to its use for optical, electro-optical and electronic purposes, in particular in LC displays, and to LC displays comprising it.

The present invention relates to a liquid crystal (LC) medium comprising polymerisable compounds, to a process for its preparation, to its use for optical, electro-optical and electronic purposes, in particular in LC displays, and to LC displays comprising it.

Provided are a liquid crystal composition satisfying at least one of characteristics including a high maximum temperature, a low minimum temperature, small viscosity, suitable optical anisotropy and large negative dielectric anisotropy, or the liquid crystal composition having a suitable balance regarding at least two of the above characteristics; and an AM device including the composition. The liquid crystal composition contains a specific compound having large negative dielectric anisotropy as a first component, and a specific compound having small viscosity as a second component, and may contain a specific component having high maximum temperature or small viscosity as a third component, a specific component having negative dielectric anisotropy as a fourth component, or a specific compound having a polymerizable group as an additive.

A compound represented by Formula (1):

##STR00001## R.sup.1 is hydrogen or an alkyl group that may be substituted; rings A.sup.1 to A.sup.2 are cyclohexylene or phenylene that may be substituted; a is 0 to 4; Z.sup.1 is a single bond or an alkylene group that may be substituted; Sp.sup.1 to Sp.sup.3 are a single bond or an alkylene that may be substituted; M.sup.1 to M.sup.4 are H, F, Cl, or an alkyl group that may be substituted; R.sup.2 and R.sup.3 are hydrogen, a group represented by Formula (1-a), or an alkyl group having 1 to 5 carbon atoms that may be substituted; and at least one of R.sup.2 and R.sup.3 is a group represented by Formula (1-a);

##STR00002## Sp.sup.4 is a single bond or an alkylene group that may be substituted; R.sup.4 and R.sup.5 are hydrogen or an alkyl group; and at least one of R.sup.4 and R.sup.5 is an alkyl group.