The invention provides a liquid crystal compound satisfying at least one of physical properties such as a high stability to heat or light, a high clearing point (or a high maximum temperature), a low minimum temperature of a liquid crystal phase, a small viscosity, a suitable optical anisotropy, a small dielectric anisotropy, a suitable elastic constant and a good compatibility with other liquid crystal compounds, a liquid crystal composition including this compound, and a liquid crystal display device containing this composition. The invention provdes a compound represented by formula (1):

##STR00001##

where R.sup.1 and R.sup.2 is alkyl having 1 to 20 carbons or the like; one of L.sup.1 and L.sup.2 is both hydrogens, and the other is both fluorines; Z.sup.1 and Z.sup.2 are independently a single bond, —COO—, —OCO—, —OCH.sub.2—, —CH.sub.2O—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2CH.sub.2—, —CH═CH—, —C≡C— or the like.

A liquid crystal composition is described, containing a chiral agent and achiral component T containing at least one compound 1 having an unsubstituted or methyl group-substituted dioxane ring and having at least one —COO— or —CF.sub.2O— as a connecting group, and exhibiting an optically isotropic liquid crystal phase.

The present invention relates to aromatic isothiocyanates of formula U

##STR00001##

as defined in claim 1, to liquid-crystalline media comprising one or more compounds of formula U and to high-frequency components comprising these media, especially microwave components for high-frequency devices, such as devices for shifting the phase of microwaves, tunable filters, tunable metamaterial structures, and electronic beam steering antennas, e.g. phased array antennas.

The present invention discloses a liquid crystal composition and a display device containing the same. The liquid crystal composition comprises one or more compounds of general Formula I; one or more compounds of general Formula II; and one or more compounds of general Formula III. The liquid crystal composition provided in the present invention has the properties of large optical and dielectric anisotropies, high clearing point, fast response speed, high resistivity, and good high-temperature and UV stability, and is applicable to a liquid crystal display (LCD), and particularly an LCD display requiring fast response speed, such that a good display effect of images without ghosting can be achieved when the LCD display works in a harsh environment.

##STR00001##

Liquid-crystalline media comprising one or more compounds of formula T ##STR00001##
as defined in claim 1, and high-frequency components comprising these media, especially microwave components for high-frequency devices, such as devices for shifting the phase of microwaves, tunable filters, tunable metamaterial structures, and electronic beam steering antennas, e.g. phased array antennas.

One aspect is contemplated for providing a device having a liquid crystal material exhibiting a dielectric constant of 1000 or more at a temperature at which a specific liquid crystal phase is developed, and a unit configured to apply voltage to the liquid crystal material at the temperature at which the specific liquid crystal phase is developed.

To provide 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 heat, or having a suitable balance regarding at least two of the characteristics; and an AM device having characteristics such as short response time, a large voltage holding ratio, low threshold voltage, a large contrast ratio and long service life. The composition has negative dielectric anisotropy and contains a specific compound having large negative dielectric anisotropy as a first component, 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.

The present invention relates to liquid crystal media comprising polymerisable mesogenic compounds with a bent shape, and to electro-optical displays comprising these media as light modulation media. In particular the electro-optical displays according to the present invention are displays, which are operated at a temperature, at which the liquid crystal modulation media are in an optically isotropic phase, preferably in a blue phase.

The subject is to provide liquid crystal display device having 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 liquid crystal display device having a liquid crystal alignment film formed on the opposing surfaces of a pair of substrates, and a liquid crystal composition therebetween, wherein the liquid crystal alignment film includes a polymer derived from a polyamic acid having a photodegradable group, and the liquid crystal composition includes at least one compound represented by formula (1) as a first component:

##STR00001##

R.sup.1 is alkyl having 1 to 12 carbons or the like; ring A is 1,4-cyclohexylene, 1,4-phenylene or the like; Z.sup.1 is a single bond or the like; X.sup.1 and X.sup.2 are hydrogen or fluorine; Y.sup.1 is fluorine or the like; and a is 1, 2, 3 or 4.

An object of the present invention is to provide a composition that has positive Δ∈, exhibits a liquid crystal phase over a wide temperature range, has low viscosity, excellent solubility at low temperatures, and high resistivity and voltage holding ratio, and is stable against heat and light. By using this composition, IPS or TN liquid crystal display devices and the like that have excellent display quality and suppress display failures such as image-sticking and drop marks are provided in high yield.

Provided is a composition that contains at least one selected from the group consisting of compounds represented by general formulae (i) and (ii) and at least one selected from compounds represented by general formula (iii). Moreover, a liquid crystal display device using the composition and an IPS or FFS device that uses the composition are provided.