The subject is to show a liquid crystal display device having 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 means concerns a liquid crystal display device including a first substrate, a second substrate and a liquid crystal composition having positive dielectric anisotropy, which is placed between these substrates, wherein the liquid crystal composition has a nematic phase and includes at least one compound selected from the group of compounds represented by formula (1) as a first component:

##STR00001##

in formula (1), R.sup.1 is alkyl or the like; ring A is 1,4-phenylene or the like; Z.sup.1 is a single bond or the like; X.sup.1 and X.sup.2 is hydrogen or fluorine; Y.sup.1 is fluorine or the like; and m is 0, 1, 2, 3 or 4.

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.

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.

It is an object of the present invention to provide a liquid crystal composition having a positive as well as a liquid crystal phase in a wide temperature range, good solubility at low temperature, excellent adaptability to an ODF process, high specific resistance, a high voltage holding ratio, and stability to heat and light. In order to achieve this object, a liquid crystal composition containing a compound represented by Formula (i) and a compound represented by Formula (ii) is provided.

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.

Provided is an LCD device having excellent high speed responsiveness. This LCD device contains a polymer or a copolymer in a liquid crystal composition sandwiched between two transparent substrates, at least one of which has an electrode, and the content of the polymer or the copolymer is 1% by mass or greater and less than 40% by mass of the total mass of the liquid crystal composition and the polymer or the copolymer. This LCD device can be applied to various operation modes such as TN, STN, ECB, VA, VA-TN, TPS, FFS, a cell, OCB, and cholesteric liquid crystals.

Provided are a liquid crystal composition including at least one or more compounds represented by General Formula (i) and at least one or more compounds represented by General Formula (M-1), in which the dielectric constant anisotropy at 25 C. is larger than 0 and 5 or less; and a liquid crystal display element using this composition. The liquid crystal composition has a positive , can have the electrical capacity of the liquid crystal layer (C.sub.LC) reduced to a low level, can be driven at a voltage that is practically sufficiently low, and satisfies at least any one of the requirements of maintaining a liquid crystal phase over a wider temperature range, low viscosity, satisfactory solubility at low temperature, high specific resistance or voltage retention rate, and stability to heat or light; and provide an excellent liquid crystal display element.

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

The means concerns 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 the group of 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.