IMPROVED LIQUID CRYSTAL MIXTURE

摘要

An improved twisted nematic liquid crystal display device operating in the high multiplex mode, having a high contrast and containing a liquid crystal mixture which has a ratio of the elastic constants K3/K1 as small as possible but not more than 0.9 and a ratio of Δε/ε of at most +0.3 and comprises at least three liquid crystal materials: (a) at least 10 wt% of a first liquid crystal material comprising at least one of liquid crystal compounds represented by general formula (I), wherein R1 represents a group R or OR; and R2 represents R or OR; R being in each case independently a straight chain alkyl group having up to 12 carbon atoms wherein one or two non-adjacent CH2 groups may be replaced by -O- and/or -CH=CH-, two oxygen atoms not being directly attached to one another, A is 1,4-phenylene or trans-1,4-cyclohexylene, Z1 is -CO-O-, -O-CO-, -CH¿2?-O-, -OCH2-, -CH2CH2- or a single bond, Q?1¿ is 1,4-phenylene or trans-1,4-cyclohexylene, and m is 0, 1, or 2, (b) less than 10 wt% of a second liquid crystal material comprising one or more liquid crystal compounds having a distinct positive dielectric anisotropy (Δε » +3); and, (c) less than 90 wt% of a third liquid crystal material comprising at least one liquid crystal compound having a negative or substantially 0 dielectric anisotropy, wherein (1) the first liquid crystal material comprises at least one of liquid crystal compounds represented by general formulae (Ib) to (Ii), and/or (2) the third liquid crystal material comprises at least one liquid crystal compound represented by general formulae (IIId) to (IIIh), (III6) to (III15) and/or (III16) and (III17).