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

##STR00001##

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.

The invention relates to a liquid-crystalline medium, preferably having a nematic phase and negative dielectric anisotropy, which comprises a) one or more compounds of formula I ##STR00001## and b) one or more compounds selected from the group of compounds of the formulae II and III ##STR00002##
in which the parameters have the respective meanings indicated in claim 1, to the use thereof in an electro-optical display, particularly in an active-matrix display based on the VA, ECB, PALC, IPS or FFS effect, to displays of this type which contain a liquid-crystalline medium of this type, and to the use of the compounds of formula I for reduction of the dispersion of the birefringence of a liquid-crystalline medium which comprises one or more compounds of the formulae II and/or III.

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.

Provided are a dye compound, a composition comprising the dye compound, and a display device using the dye compound. The dye compound is represented by Formula 1.

##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.

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.

The invention relates to an electro-optical liquid-crystal display having a re-alignment layer for re-alignment of the liquid crystals whose field has a component, crucial for the re-alignment, parallel to the liquid-crystal layer, containing a liquid-crystalline medium, characterized in that it comprises one or more compounds of the formula I1 to I3, (I1) (I2) (I3) and at least one compound of the formula II, in which the parameters R.sup.11, R.sup.11*, Z.sup.0, Sp, k, l, p, Y.sup.21 to Y.sup.22, R.sup.21 and R.sup.22 have the meanings indicated in claim 1.

A liquid crystal composition includes one or more compounds represented by Chemical Formula 1. ##STR00001## In Chemical Formula 1, ##STR00002##
are a cyclohexane or tetrahydropyran, and R1 and R2 are each independently hydrogen, a C1 to C8 alkyl group, a C2 to C8 alkenyl group, or a C1 to C8 alkoxy group.

The present invention provides a liquid crystal composition and a liquid crystal display device thereof. The liquid crystal composition comprises at least one compound of general formula I and at least one compound of general formula II. The liquid crystal composition has a larger vertical dielectric constant (?.sub.?), a larger ratio of the vertical dielectric constant to the absolute value of dielectric anisotropy (?.sub.?/|??|), a larger K.sub.ave value and a higher transmittance while maintaining an appropriate clearing point, an appropriate optical anisotropy, and an appropriate absolute value of the dielectric anisotropy, such that the liquid crystal display device comprising the same has a better contrast, a faster response speed and a better transmittance while maintaining an appropriate range of operating temperature and an appropriate threshold voltage. ##STR00001##

The invention relates to dielectrically positive liquid crystalline media comprising a compound of formula I

##STR00001##

wherein the parameters have the meaning given in claim 1 and to liquid crystal displays comprising these media, especially to active matrix displays and in particular to TN and IPS mode displays.