Liquid-crystalline medium and liquid-crystal display comprising the same

Abstract

The invention relates to a liquid-crystalline medium, preferably having a nematic phase and dielectric anisotropy of 0.5 or more, which has particular dielectric properties, in that it has either a dielectric constant perpendicular to the director (shown in the description) in the range of 2 or more to less 8 or less and at the same time a ratio of the dielectric constant perpendicular to the director (shown in the description) to the dielectric anisotropy (shown in the description), i.e. (shown in the description) of 1.0 or more or or a dielectric constant perpendicular to the director (shown in the description) of 8 or more and a dielectric anisotropy (shown in the description) of 26 or less and preferably comprises one or more compounds having a high dielectric constant perpendicular to the director (shown in the description) and a high average dielectric constant (shown in the description), to the use thereof in an electro-optical display, particularly in an active-matrix display based on the 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 improvement of the transmission and / or response times of a liquid-crystalline medium which comprises one or more additional mesogenic compounds.

Description

technical field [0001] The present invention relates to novel liquid crystal media, in particular liquid crystal media for liquid crystal displays, and these liquid crystal displays, in particular liquid crystals using dielectrically positive liquid crystals utilizing the IPS (In-Plane Switching) or preferably FFS (Fringe Field Switching) effect monitor. Occasionally the latter is also referred to as SG-FFS (super-controlled FFS ( s uper g rip FFS)) effect. For this effect, dielectrically positive liquid crystals are used, which contain one or more compounds with both high dielectric constants parallel to the molecular director and perpendicular to the molecular director, resulting in large average dielectric constants and high dielectric constants. electrical ratio, and preferably at the same time a relatively small dielectric anisotropy. The liquid-crystalline medium optionally additionally comprises dielectrically negative, dielectrically neutral compounds or both. Liq...

AI Technical Summary

Problems solved by technology

However, these displays using dielectrically negative liquid crystals have a serious disadvantage: they require higher operating voltages than individual displays using dielectrically positive liquid crystals

[0030] In addition to their relatively poor transmittance and their relatively long response times, the hitherto disclosed MLC displays have other disadvantages

These are for example their relatively low contrast ratio, their relatively high viewing angle dependence and difficulty in grayscale reproduction in these displays, especially when viewed from oblique viewing angles, as well as their insufficient VHR and their insufficient lifetime

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