An optically anisotropic layer including a polymer and a compound having a mesogen skeleton, wherein the polymer has a property such that a film of the polymer that is formed by a coating method using a solution of the polymer satisfies nz(P)>nx(P)ny(P), wherein nx(P) is a refractive index in a direction which, among in-plane directions of the film, gives a maximum refractive index, ny(P) is a refractive index in a direction which is perpendicular to the direction of nx(P) among the in-plane directions of the film, and nz(P) a refractive index in a thickness direction of the film, and the compound having a mesogen skeleton shows an in-plane retardation with reverse wavelength distribution under specific conditions.

Shown is a compound represented by formula (1). For example, R.sup.1 is alkyl having 1 to 15 carbons; MES is a mesogen group having at least one ring; Sp.sup.1 is a single bond or alkylene having 1 to 10 carbons; M.sup.1 is methyl; and R.sup.2, M.sup.2 and M.sup.3 are hydrogen. ##STR00001##

The application relates to a device for regulating the entry of light into a room, which comprises a switchable layer of specific design comprising a twisted nematic liquid-crystalline medium and a dichroic compound.

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 dielectric anisotropy and a short helical pitch, or the liquid crystal composition 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 optically active compound as an additive, and a specific compound having high maximum temperature or small viscosity as a first component, and may contain a specific compound having positive dielectric anisotropy as a second component, or a specific compound having negative dielectric anisotropy as a third 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 Z.sup.32: single-bond or CF.sub.2O, L.sup.31 to L.sup.34: fluorine, Y.sup.3: fluorine, for example.

A liquid crystal composition and the use thereof are provided. The liquid crystal composition comprises 15-30% by weight of three or more compounds of general formula I; the general formula I must comprises at least two compounds of general formula I-1; wherein, by weight of the total amount of the liquid crystal composition, the total amount of the compounds of general formula I-1 is no lower than 10%, and the content of each of the compounds of general formula I-1 is no higher than 8%. The liquid crystal composition has appropriately high optical anisotropy, higher dielectric anisotropy, lower threshold voltage, suitable elastic constant, suitable temperature range of nematic phase, good reliability and heat stability, and good low-temperature intersolubility.

##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.

A liquid crystal composition and use thereof in the liquid crystal display field. The liquid crystal composition includes, in percentages by weight, 5-40% of one or more compounds represented by general formula I, 2-30% of one or more compounds represented by general formula II, and 20-70% of one or more compounds represented by general formula III, and may further include 4-30% of one or more compounds represented by general formula IV and/or 5-25% of one or more compounds represented by general formulas V to IX. The combined use of the above-mentioned compounds can effectively reduce the rotational viscosity of the liquid crystal composition, improve related properties of the mixed liquid crystal, and thus reduce the response time thereof. The liquid crystal composition can be used for a fast-response liquid display in a variety of display modes.

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 compound represented by Formula (1):

##STR00001## R.sup.1 is hydrogen or an alkyl group that may be substituted; rings A.sup.1 to A.sup.2 are cyclohexylene or phenylene that may be substituted; a is 0 to 4; Z.sup.1 is a single bond or an alkylene group that may be substituted; Sp.sup.1 to Sp.sup.3 are a single bond or an alkylene that may be substituted; M.sup.1 to M.sup.4 are H, F, Cl, or an alkyl group that may be substituted; R.sup.2 and R.sup.3 are hydrogen, a group represented by Formula (1-a), or an alkyl group having 1 to 5 carbon atoms that may be substituted; and at least one of R.sup.2 and R.sup.3 is a group represented by Formula (1-a);

##STR00002## Sp.sup.4 is a single bond or an alkylene group that may be substituted; R.sup.4 and R.sup.5 are hydrogen or an alkyl group; and at least one of R.sup.4 and R.sup.5 is an alkyl group.