The present invention relates to a liquid-crystalline medium based on a mixture of polar compounds having negative dielectric anisotropy (), which is distinguished by the fact that it has a value for the ratio .sub.1/n.sup.2 in the range 6-45 with a clearing point of >60 C. and a of 2.3. Media of this type are particularly suitable for electro-optical displays having active-matrix addressing based on the ECB, PA LCD, FFS or IPS effect.

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 provides a liquid crystal composition and a liquid crystal display device thereof. The liquid crystal composition comprises at least one compound of general formula I and at least one compound of general formula II. The liquid crystal composition has a larger vertical dielectric constant (.sub.), a larger ratio of the vertical dielectric constant to the absolute value of dielectric anisotropy (.sub./||), a larger K.sub.ave value and a higher transmittance while maintaining an appropriate clearing point, an appropriate optical anisotropy, and an appropriate absolute value of the dielectric anisotropy, such that the liquid crystal display device comprising the same has a better contrast, a faster response speed and a better transmittance while maintaining an appropriate range of operating temperature and an appropriate threshold voltage.

##STR00001##

Object To provide a tilt-imparted liquid crystal display element that is obtained through UV irradiation of a polymerizable liquid crystal composition, whose drive voltage can be reduced with a fast decay time maintained, and that is well balanced between characteristics, such as decay time, drive voltage, and transmittance. A polymerizable liquid crystal composition for use in it is also provided. Solution A liquid crystal display element has polymer networks formed in the liquid crystal phase 5 in FIG. 3. The polymer networks are formed by polymerizing a polymerizable liquid crystal composition that contains, as essential ingredients, a radically polymerizable monomer component (A), a liquid crystal material (B), and a polymerization initiator (C) that has a molecular structure resulting from substituting any two or more hydrogen atoms in the aromatic nucleus in the molecular structure of an alkylphenone-based photopolymerization initiator, for example with a C1-10 alkyl group (i).

A liquid crystal compound is represented by formula (1): ##STR00001## In formula (1), R.sup.1 is alkyl or the like; ring A.sup.1 and ring A.sup.2 are independently 1,4-cyclohexylene, 1,4-phenylene or the like; Z.sup.1, Z.sup.2 and Z.sup.3 are independently a single bond, CF.sub.2O or the like; X.sup.1 is fluorine, chlorine, CF.sub.3 or the like; L.sup.1 and L.sup.2 are independently hydrogen, fluorine or the like; a and b are independently 0, 1, 2 or 3; and W is a group represented by formula (1a) or formula (1b); ##STR00002## In formula (1a) and formula (1b), L.sup.3 to L.sup.8 are independently hydrogen, fluorine or the like.

A liquid crystalline compound, a liquid crystal composition, and a liquid crystal display element are provided. The liquid crystalline compound satisfying at least one physical property among high stability against heat and light, high transparency, low minimum temperature of the liquid crystal phase, low viscosity, proper optical anisotropy, negatively large dielectric anisotropy, proper elastic constant, good compatibility with other liquid crystalline compounds at room temperature and low temperature. The liquid crystalline compound represented by formula (1).

##STR00001##

Disclosed are a liquid crystal composition and a liquid crystal display component. The liquid crystal composition comprises one or more compounds as represented by structural formula I-1 and/or one or more compounds as represented by structural formula I-2, one or more compounds as represented by structural formula II, and one or more compounds as represented by structural formula III:

##STR00001##

The liquid crystal display component includes the liquid crystal composition. The liquid crystal composition has a lower viscosity, can achieve a fast response, and further has a moderate dielectric anisotropy , a moderate optical anisotropy n, and a high stability to heat and light. The liquid crystal display component including the liquid crystal composition has the characteristics of a broader nematic phase temperature range, a suitable birefringence anisotropy, a very high electrical resistivity, a good anti-ultraviolet property, a high charge retention ratio, and a fast response.

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.

Disclosed herein are novel liquid crystal compounds of formula I:

##STR00001##

wherein each of the substituents is given the definition as set forth in the Specification and Claims. Also disclosed are liquid crystal media including the novel liquid crystal compounds of formula I, which are suitably applied in an active matrix display device.