A liquid crystal composition for dimming that satisfies at least one of characteristics such as a high maximum temperature, a low minimum temperature, a small viscosity, a large optical anisotropy and a large positive dielectric anisotropy, or that is suitably balanced between at least two of these characteristics, and a liquid crystal dimming device including this composition. A liquid crystal composition for dimming that includes a specific compound having a large positive dielectric anisotropy as a first component and that may include a specific compound having a high maximum temperature or a low minimum temperature as a second component and a specific compound having a large dielectric anisotropy in the minor axis direction as a third component.

The present invention discloses a liquid crystal composition, comprising: at least a first compound selected from the group consisting of a compound of general Formula I-1, a compound of general Formula I-2, and a combination thereof, and at least a second compound selected from the group consisting of a compound of general Formula II-1, a compound of general Formula II-2, a compound of general Formula II-3, a compound of general Formula II-4 and a combination thereof. The liquid crystal composition provided in the present invention has the properties of appropriate optical and dielectric anisotropies, high clearing point, existence of a nematic phase over a wide range of temperature, low viscosity and good high-temperature stability. The liquid crystal composition is applicable to a liquid crystal display (LCD) device, to enable the LCD device to have such properties as short response time, excellent display effect at high temperature, and others. ##STR00001##

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.

The subject is to show a liquid crystal composition in which the homeotropic alignment of liquid crystal molecules can be achieved by the action of a polymer, and a liquid crystal display device including this composition. The means concerns a nematic liquid crystal composition that has positive dielectric anisotropy and that includes a specific liquid crystal compound having a large positive dielectric anisotropy as a first component and a polar compound having a polymerizable group as a first additive, and the composition may include a specific liquid crystal compound having a high maximum temperature or a small viscosity as a second component, a specific liquid crystal compound having a positive dielectric anisotropy as a third component, a specific liquid crystal compound having negative dielectric anisotropy as a fourth component, and a polymerizable compound as a second additive, and concerns a liquid crystal display device including the composition.

A liquid-crystalline medium which comprises at least one compound selected from the group of compounds of the formulae IA to IH,

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in which Z.sup.1 denotes a single bond, CH.sub.2CH.sub.2, CH?CH, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, COO, OCO, C.sub.2F.sub.4, (CH.sub.2).sub.4, CHFCHF, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, C?C, CF?CF, CH?CHCHO or CH.sub.2CF.sub.2O,
and the use thereof for an active-matrix display, in particular based on the VA, PSA, PS-VA, PALC, FFS, PS-FFS, SA-VA, PS-IPS or IPS effect.

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

The present application relates to a liquid crystal cell and a use of the liquid crystal cell. The present application can provide a liquid crystal cell which is capable of switching between a transparent mode and a scattering mode by using a non-ionic compound as a liquid crystal additive for realizing the EHDI characteristics and has excellent performance such as a driving voltage characteristic, a haze characteristic and reliability by securing solubility of the additive for liquid crystals. Such a liquid crystal cell can be applied to various light modulation devices such as a smart window, a window protective film, a flexible display device, a light shielding plate for transparent display, an active retarder for 3D image display, or a viewing angle adjusting film.

Liquid-crystalline (LC) media having positive dielectric anisotropy and liquid-crystal displays (LCDs) containing these media, especially displays addressed by an active matrix and in particular to LC displays of the TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, SA-HB-FFS, SA-XB-FFS, polymer stabilised SA-HB-FFS, polymer stabilised SA-XB-FFS, positive VA or positive PS-VA type.

Provided are a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature, a low minimum temperature, small viscosity, large optical anisotropy, 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 may contain a specific compound having small viscosity or a low minimum temperature as a first component, a specific compound having large optical anisotropy and negative dielectric anisotropy as a second component, a specific compound having a high maximum temperature or small viscosity as a third component, a specific compound having negative dielectric anisotropy or a low minimum temperature as a fourth component, or a specific compound having a polymerizable group as an additive component.

Shown 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 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 positive dielectric anisotropy as a first component and a specific compound having small viscosity as a second component, and the composition 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.