The invention relates to a liquid-crystalline medium based on a mixture of polar compounds having positive dielectric anisotropy, characterised in that it comprises one or more compounds of the formula I in a total concentration of 40%,

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in which the parameters have the meanings indicated in claim 1, and to the use of the liquid-crystalline medium for electro-optical purposes, in particular in liquid-crystal light valves for lighting devices for motor vehicles, and to liquid-crystal light valves which comprise this medium and lighting devices for motor vehicles which contain such liquid-crystal light valves.

An object of the present invention is to provide a composition that realizes high n, has a wide liquid crystal phase temperature range, small viscosity, excellent low-temperature solubility, and high resistivity and voltage holding ratio, and is stable against heat and light, and to provide a liquid crystal composition having an excellent lens effect and excellent chemical stability using the composition, and a liquid crystal display device and a liquid crystal lens that use the liquid crystal composition. The present invention provides a liquid crystal composition that contains one or two or more compounds represented by general formula (i) and one or two or more compounds represented by general formula (ii), a liquid crystal display device using the liquid crystal composition, a liquid crystal lens using the liquid crystal composition, and a birefringence lens for stereoscopic image display using the liquid crystal composition.

To provide a liquid crystal compound satisfying at least one of high stability to heat, light and so forth, a high clearing point, low minimum temperature of a liquid-crystal phase, small viscosity, suitable optical anisotropy, large dielectric anisotropy, a suitable elastic constant and excellent compatibility with other liquid-crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition. A compound is represented by formula (1-1). ##STR00001##
For example, R.sup.1 and R.sup.2 are independently hydrogen, alkyl having 1 to 10 carbons, alkenyl having 3 to 10 carbons and alkoxy having 1 to 9 carbons; ring A.sup.1 is 1,4-cyclohexylene; ring A.sup.2 and ring A.sup.3 are independently 1,4-cyclohexylene or 1,4-phenylene; Z.sup.1 is a single bond or (CH.sub.2).sub.2; l is 0 or 1, m and n are 0, 1 or 2, a sum: l+m+n is 0, 1 or 2; x is 0 or 1.

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

A low birefringence ferroelectric liquid crystal (FLC) mixture composed of at least two components shows birefringence in the range 0.05 to 0.14, which is suitable for the modern display and photonic devices. The cell gap can be tuned from 1.5 m to 4 m to reduces the fabrication complexity and chromatic distortion by electro-optical modulation. The FLC mixtures can be employed in a wide temperature range. The characteristics of the said FLC mixture can be tuned by tuning the concentration of the constituents of the mixture. The helical pitch of the FLC mixtures can be varied from 100 nm to 10 m. A smectic tilt angle can be varied between 17 to 45 and the spontaneous polarization can be tuned over a wide range to meet requirements of different electro-optical modes, and the FLC mixture is applicable for a wide variety of electro-optical effects.

A flexoelectric liquid crystal composition containing at least one kind of smectic liquid crystal compound, a chiral dopant, and a charge scavenger, and exhibiting photoconductivity.

A compound represented by formula (1). For example, R.sup.1, R.sup.2 and R.sup.3 are alkyl having 1 to 15 carbons; ring A.sup.1 and ring A.sup.3 are cyclohexyl or phenyl, ring A.sup.2 is 1,4-cyclohexylene or 1,4-phenylene; Z.sup.1 and Z.sup.2 are a single bond or alkylene having 1 to 10 carbons; a is 0, 1, 2, 3 or 4; c, d and e are 0, 1, 2, 3 or 4; and P.sup.1 to P.sup.3 are a polymerizable group represented by formula (P-1); wherein M.sup.1 and M.sup.2 are hydrogen or alkyl having 1 to 5 carbons; and R.sup.4 is a polar group represented by formulas (1a) to (1c); wherein Sp.sup.5 and Sp.sup.6 are a single bond or alkylene having 1 to 10 carbons; S.sup.1 is >CH, and S.sup.2 is >C<; and X.sup.1 is OH.

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The present invention aims to provide a composition having a high n, a wide temperature range of a liquid crystal phase, low viscosity, good solubility at a low temperature, high resistivity, a high voltage holding ratio, and stability against heat and light; a liquid crystal composition containing the composition, the liquid crystal composition having a good lens effect and good chemical stability; a liquid crystal display device including the liquid crystal composition; and a liquid crystal lens including the liquid crystal composition. The liquid crystal composition contains one or two or more compounds represented by general formula (i) and one or two or more compounds represented by general formula (ii).

An object of the present invention is to provide a composition that realizes high n, has a wide liquid crystal phase temperature range, small viscosity, excellent low-temperature solubility, and high resistivity and voltage holding ratio, and is stable against heat and light, and to provide a liquid crystal composition having an excellent lens effect and excellent chemical stability using the composition, and a liquid crystal display device and a liquid crystal lens that use the liquid crystal composition. The present invention provides a liquid crystal composition that contains one or two or more compounds represented by general formula (i) and one or two or more compounds represented by general formula (ii), a liquid crystal display device using the liquid crystal composition, a liquid crystal lens using the liquid crystal composition, and a birefringence lens for stereoscopic image display using the liquid crystal composition.

The present invention relates to dielectrically positive liquid-crystalline media comprising one or more compounds of the formula I and/or TINUVIN 770,

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in which the parameters have the respective meanings indicated in the specification, and optionally one or more further dielectrically positive compounds and optionally one or more further dielectrically neutral compounds, and to liquid-crystal displays, especially active-matrix displays and in particular TN, IPS and FFS displays, containing these media.