A liquid crystal composition satisfies at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy, large dielectric anisotropy and high stability to ultraviolet light, or having a suitable balance regarding at least two of the characteristics. The liquid crystal composition contains a quencher as an additive, and may contain a specific compound having large positive dielectric anisotropy as a first component, a specific compound having high maximum temperature or small viscosity as a second component, or a specific compound having large negative dielectric anisotropy as a third component.

Shown is a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy, large dielectric anisotropy and small frequency dependence, or has 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 positive dielectric anisotropy as a first component, and a specific compound having small viscosity as a second component, and may contain a specific compound having high maximum temperature or small viscosity as a third component, a specific compound having positive dielectric anisotropy as a fourth component or a specific compound having negative dielectric anisotropy as a fifth component.

The subject is to show a liquid crystal display device that has characteristics such as 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 disclosure relates to a liquid crystal display device including an electrode group formed on one or both of a pair of substrates that are opposed to each other, and a plurality of active devices connected to the electrode group, and a liquid crystal alignment film formed on the opposing surfaces of the pair of substrates, and a liquid crystal composition sandwiched in between the pair of substrates, and the liquid crystal composition includes at least one compound selected from the group of compounds represented by formula (1) as a first component. ##STR00001##

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.

Shown is a liquid crystal display device including a first substrate, a second substrate and a liquid crystal composition having a nematic phase, which is placed between these substrates, wherein the liquid crystal composition includes at least one compound selected from compounds represented by formula (1) as a first component: ##STR00001##
wherein in formula (1), R.sup.1 and R.sup.2 are alkyl or the like; ring A and ring C are 1,4-phenylene or the like; ring B is 2,3-difluoro-1,4-phenylene or the like; Z.sup.1 and Z.sup.2 are a single bond or the like; and m is 1, 2 or 3, n is 0 or 1, and the sum of m and n is 3 or less.

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

A polymerizable compound-containing liquid crystal composition of the present invention relates to a liquid crystal composition containing a polymerizable compound represented by general formula (I) and a compound represented by general formula (II) and can be used for a liquid crystal display device imparted with liquid crystal aligning ability by polymerization. The polymerizable liquid crystal composition is required to cause no precipitation in a wide temperature range and have a low viscosity corresponding to fast switching, and a liquid crystal display device using the composition is required to have more stable alignment after polymerization and to cause no defect in display characteristics. In the present invention, the problems can be solved using a specified compound.

The present invention provides a spontaneous orientation aid for a liquid crystal composition, containing one kind or two or more kinds of a compound having a partial structure represented by the general formula (i), wherein Z.sup.i1 represents a single bond, etc.; A.sup.i1 represents a divalent 6-membered aromatic group, etc.; m.sup.i1 represents an integer of 1 to 5; and K.sup.i1 represents a structure represented by any of the following formulae (K-1) to (K-8), wherein W.sup.K1 represents a methine group, etc.; X.sup.K1 and Y.sup.K1 each represent CH.sub.2, etc.; Z.sup.K1 represents an oxygen atom, etc.; and U.sup.K1, V.sup.K1, and S.sup.K1 each represent a methine group, etc.:

##STR00001##

A polymerizable compound-containing liquid crystal composition of the present invention relates to a liquid crystal composition containing a polymerizable compound represented by general formula (I) and a compound represented by general formula (II) and can be used for a liquid crystal display device imparted with liquid crystal aligning ability by polymerization. The polymerizable liquid crystal composition is required to cause no precipitation in a wide temperature range and have a low viscosity corresponding to fast switching, and a liquid crystal display device using the composition is required to have more stable alignment after polymerization and to cause no defect in display characteristics. In the present invention, the problems can be solved using a specified compound.

To show a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature thereof, small viscosity, suitable optical anisotropy, large positive dielectric anisotropy or having a suitable balance regarding at least two of the characteristics, and an AM device including the liquid crystal composition. The liquid crystal composition contains a specific compound having high maximum temperature and low minimum temperature as a first component, and the liquid crystal composition may contain a specific compound having large positive dielectric anisotropy as a second component, a specific compound having high maximum temperature or small viscosity as a third component, a specific compound having large positive dielectric anisotropy as a fourth component, or a specific compound having negative dielectric anisotropy as a fifth component.