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 subject is to show 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.

Provided are a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature, a low minimum temperature, small viscosity, suitable optical anisotropy and large dielectric anisotropy, or having a suitable balance regarding at least two characteristics, and an AM device containing the composition.

The liquid crystal composition contains a specific compound having small viscosity as a first component, and may contain a specific compound having negative dielectric constant as a second component, a specific compound having a high maximum temperature or small viscosity as a third component, or a specific compound having a polymerizable group as an additive.

Provided are a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small 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 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 negative dielectric anisotropy as a fourth component, or a specific compound having a polymerizable group as an additive component.

Provided are a liquid-crystal-medium having stability to heat, light and so forth, a wide liquid-crystal-phase temperature-range and significantly large dielectric-anisotropy and developing an optically isotropic liquid-crystal-phase; and various optical-devices used in a wide temperature-range, having short response-time, a large contrast-ratio and low drive-voltage and suppressing decrease in an effective dielectric-constant in a high-frequency range.

A Liquid-crystal composition contains achiral-component T containing at least one compound selected from a first component represented by formula (1) and at least one compound selected from a second component represented by formula (2) or (3) and a chiral-agent to develop optically-isotropic liquid-crystal-phase:

##STR00001##

In formula (1), R.sup.1: alkyl, ring A.sup.1: 1,4-cyclohexylene, ring B.sup.1: 1,4-phenylene, L.sup.11 to L.sup.14: fluorine, Y.sup.1: fluorine, n.sup.1: 1 or 2, R.sup.2: alkyl, Z.sup.21 and Z.sup.22: single-bond or CF.sub.2O, L.sup.21 to L.sup.23: fluorine, Y.sup.2: fluorine, R.sup.3: alkyl, Z.sup.31 and 2.sup.32: single-bond or CF.sub.2O, L.sup.31 to L.sup.34: fluorine, Y.sup.3: fluorine, for example.

The invention relates to compounds of the formula I, to a liquid-crystalline medium which comprises at least one compound of the formula I, ##STR00001##
in which
R.sup.1, R.sup.1*, L.sup.1, L.sup.2, L.sup.3 and L.sup.4 have the meanings indicated herein,
and to the use thereof for an active-matrix display, in particular based on the VA, PSA, PS-VA, PM-VA, PALC, IPS, PS-IPS, SA-VA, SS-VA, FFS or PS-FFS effect.

Provided 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 high maximum temperature or low viscosity as a second component, and may contain a specific compound having negative dielectric anisotropy as a third component, or a specific compound having a polymerizable group as an additive.

The present invention relates to a liquid crystal (LC) medium comprising a polymerizable compound, to a process for its preparation, to its use for optical, electro-optical and electronic purposes, in particular in LC displays, especially in an LC display of the polymer sustained alignment (PSA) type, and to an LC display, especially a PSA display, comprising it.

The invention relates to a liquid-crystalline medium which comprises at least one compound of the formula I,

##STR00001##

in which
R.sup.1, R.sup.1*, Z.sup.1, Z.sup.2 and L.sup.1-3 have the meanings defined herein,
and to the use thereof for an active-matrix display, in particular based on the VA, PSA, PS-VA, PALC, FFS, PS-FFS, PS-IPS or IPS effect.

Provided are a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy, large negative dielectric anisotropy, large specific resistance, high stability to ultraviolet light and high stability to heat, or the liquid crystal composition having a suitable balance regarding at least two of the characteristics; and an AM device having characteristics such as a short response time, a large voltage holding ratio, low threshold voltage, a large contrast ratio and a long service life. The liquid crystal composition has negative dielectric anisotropy and contains a specific compound having large negative dielectric anisotropy as a first component, a specific compound having low minimum temperature as a second component, and a specific compound having small viscosity as a third component, and the composition may contain a specific compound having high maximum temperature or small viscosity as a fourth component, a specific compound having negative dielectric anisotropy as a fifth component, or a specific compound having a polymerizable group as an additive component.