DE4100288A1 - Super-twist liq. crystal display - has very short switching time and large operating temp. range, good contrast and low threshold voltage - Google Patents

Abstract

Supertwist LCD has 2 plane parallel substrate plates forming the cell with a rim, which is filled with a nematic liquid crystal mixt. (I) with positive dielectric anisotropy and electrode layers and overlying orientation layers on the inside of the plates. The angle of pitch between the longitudinal axis of the mols. w.r.t the plate surface is ca. 1-30 deg. and the twist angle w.r.t. the orientation layer is 160-360 deg. (I) contains (a) component A, (b) 0-45 (wt.)% component B1, B2 and/or B3 10-80% liquid crystal component, C consisting of cpd(s) with a dielectric anisotropy of over +1.5, (d) 0-20% liquid crystal component D, consisting of cpd(s) with a dielectric anisotropy less than -1.5 and (e) an optically active component E in an amt. such that the ratio between the film thickness (distance between the plates) and the natural pitch of the chiral nematic liquid crystal mixt. is ca. 0.2-1.3; and the mixt. has a nematic phase range of at least 60 deg.C viscosity of max. mPa.s and dielectric anisotropy of at least +5 at 20 deg.C. Component A consists of cpds. of formula (AI)-(A-VI), B1 of (BI)-(BIV), B2 of (BV)-B(VIII) and B3 of (BVIII) and/or B(X) R1 and R2 independently = R = 1-12C alkyl, in which one or 2 non-adjacent -CH- gps. may be replaced by -O-, -CH=CH-, -CO-, -O-CO- or -CO-O, Z2 = -CH2CH2-, -CO-O-, -O-CO- or a single bond; ring B = 1 1,4-cyclohexylidene or 1,4-phenylene ring; ZO = -CH2CH2- or a single bond; Q = 4-CH2n+1-trans-cyclohexyl (n=1-9), 4-R-phenyl or 3-Y-4-X-phneyl (X = CN or F and Y = H or F); ring C = as ring B or trans-1,4-cyclohexylene. The cpds. used are known cpds. or can be prepd. by methods analogous to those for known cpds. (No details are given in the text). USE/ADVANTAGE - The display combines very short switching times with a large operating temp. range, high gradient, good angle dependence of the contrast and low threshold voltage.

Description

The invention relates to supertwist liquid crystal displays (SFA) with very short switching times and good slopes and angle dependencies and the ones used therein new nematic liquid-crystal mixtures.

SFA according to the preamble are known, for. B. off EP 01 31 216 B1; DE 34 23 993 A1; EP 00 98 070 A2; M. Schadt and F. Leenhouts, 17th Freiburg Workshop Liquid crystals (8.-10. 04. 87); K. Kawasaki et al. SID 87 Digest 391 (20.6.); M. Schadt and F. Leenhouts, SID 87 Digest 372 (20.1); K. Katoh et al., Japanese Journal of Applied Physics, Vol. 26, no. 11, L 1784-L 1786 (1987); F. Leenhouts et al., Appl. Phys. Lett. 50 (21), 1468 (1987); H.A. van Sprang and H.G. Koopman, J. Appl. Phys. 62 (5), 1734 (1987); T. J. Scheffer and J. Nehring, Appl. Phys. Lett. 45 (10), 1021 (1984), M. Schadt and F. Leenhouts, Appl. Phys. Lett. 50 (5), 236 (1987) and E.P. Raynes, Mol. Cryst. Liq. Cryst. Letters Vol. 4 (1), pp. 1-8 (1986). The term SFA here includes any higher twisted display element with a twist angle in amount between 160 ° and 360 °, such as the display elements according to Waters et al. (C.M. Waters et al., Proc. Soc. Inf. Disp. (New York) (1985) (3rd Intern. Display Conference, Kobe, Japan), the STN-LCD's  (DE OS 35 03 259), SBE-LCD's (T. J. Scheffer and J. Nehring, Appl. Phys. Lett. 45 (1984) 1021), OMI-LCD's (M. and F. Leenhouts, Appl. Phys. Lett. 50 (1987), 236, DST LCD's (EP OS 02 46 842) or BW-STN-LCD's (K. Kawasaki et al., SID 87 Digest 391 (20.6)).

Such SFAs are characterized in comparison to standard TN displays by significantly better slopes of the electro-optical characteristic and associated better Contrast values as well as a much lower Angular dependence of the contrast. Of special Interest are SFA with very short switching times in particular even at lower temperatures. To achieve Of short switching times were so far in particular the Viscosities of the liquid crystal mixtures optimized using mostly monotropic additives with relative high vapor pressure. However, the switching times achieved were not enough for every application.

There is thus still a great need for SFA with very short switching times and at the same time large Operating temperature range, high characteristic slope, good angle dependence of contrast and lower Threshold voltage.

The invention has for its object to provide SFA, the disadvantages mentioned above do not or only to a lesser extent and at the same time very short Have switching times.

It has now been found that this problem can be solved can, if you nematic liquid crystal mixtures used, which contain the following components:

• a) at least one component selected from the group A consisting of compounds of the formulas AI to A VI: wherein R¹ and R² are each independently R and
  R is alkyl having 1-12 C atoms, in which also one or two non-adjacent CH₂ groups may be replaced by -O-, -CH = CH-, -CO-, -O-CO- or -CO-O- .
• b) 0-45% by weight of a component B comprising at least one compound selected from the group B1 consisting of the compounds of the formulas BI to B IV: wherein R¹ and R² each independently have the meaning given for R, Z² is -CH₂CH₂-, -CO-O-, -O-CO- or a single bond, and means
  and / or at least one compound selected from the group B2 consisting of the compounds of the formulas BV to B VII: wherein R¹ has the meaning given for R,
  Z⁰ is -CH₂CH₂- or a single bond and means
  where n is 1 to 9, X is CN or F and Y is H or F,
  and / or at least one compound selected from the group B3 consisting of the compounds of the formulas B VIII and B IX: wherein R¹ and R² each independently have the meaning given for R, and means.
• c) 10-80% by weight of a liquid-crystalline component C, consisting of one or more compounds with a dielectric anisotropy of more than +1.5,
• d) 0-20% by weight of a liquid-crystalline component D, consisting of one or more compounds with a dielectric anisotropy of less than -1.5 and
• e) an optically active component E in an amount that the ratio between layer thickness (distance the plane-parallel support plates) and more natural Pitch of the nematic liquid crystal mixture is about 0.2 to 1.3.

The invention is thus an SFA with

• - two plane-parallel support plates, with a Border form a cell,
• a nematic liquid in the cell crystal mixture with positive dielectric aniso entropy,
• - Electrode layers with overlying Orientie tion layers on the insides of the carrier plates,
• - An angle between the longitudinal axis of the Molecules on the surface of the backing plates and the carrier plates of about 1 degree to 30 degrees, and
• - A twist angle of the liquid crystal mixture in the cell from orientation layer to Orientie approximately layer in the amount between 160 and 360 °, characterized in that the nematic liquid crystal mixture
  • a) at least one component selected from the group A consisting of compounds of the formulas AI to A VI: wherein R¹ and R² are each independently R and
    R is alkyl having 1-12 C atoms, in which also one or two non-adjacent CH₂ groups may be replaced by -O-, -CH = CH-, -CO-, -O-CO- or -CO-O- .
  • b) 0-45% by weight of a component B comprising at least one compound selected from the group B1 consisting of the compounds of the formulas BI to B IV: wherein R¹ and R² each independently have the meaning given for R, Z² is -CH₂CH₂-, -CO-O-, -O-CO- or a single bond, and means
    and / or at least one compound selected from the group B2 consisting of the compounds of the formulas BV to B VII: wherein R¹ has the meaning given for R,
    Z⁰ is -CH₂CH₂- or a single bond and means
    where n is 1 to 9, X is CN or F and Y is H or F,
    and / or at least one compound selected from the group B3 consisting of the compounds of the formulas B VIII and B IX: wherein R¹ and R² each independently have the meaning given for R, and means
  • c) 10-80% by weight of a liquid-crystalline component C consisting of one or more compounds having a dielectric anisotropy of more than +1.5,
  • d) 0-20 wt .-% of a liquid-crystalline component D, consisting of one or more compounds having a dielectric anisotropy of less than -1.5 and
  • e) an optically active component E in an amount such that the ratio between layer thickness (spacing of the plane-parallel support plates) and natural pitch of the nematic liquid-crystal mixture is about 0.2 to 1.3, and
• that the nematic liquid-crystal mixture is a nematic Phase range of at least 60 ° C, a viscosity of not more than 30 mPa · s and a dielectric aniso tropie of at least +5, wherein the dielectric Anisotropies of the compounds and those on the nematic Liquid crystal mixture related parameters on a Temperature of 20 ° C are related.

The invention also relates to corresponding liquid crystal mixtures for use in SFA.  

The individual compounds of the formulas A I to A VI, B I to B IV and C I to C III or other compounds which in the SFA according to the invention can be used are either known or they can be analogous to the known ones Connections are made.

Preferred liquid crystal usable in the invention mixtures contain one or more compounds Group A in a proportion of 4% to 40%, preferably 10% to 32%. Compounds of the formulas A III to A VI are preferred. In a particularly preferred embodiment The mixtures contain at the same time (a) Compounds of the formula A V and / or A VI and (b) compounds of the formula A III and / or A IV. R¹ and R² mean preferably in each case independently of one another n-alkyl 1 to 7 C atoms or (trans) -n-alkenyl with 3 to 7 C atoms.

The proportion of component (s) from group B1 is present preferably 5% to 45%, particularly preferably about 10% up to 40%. Components of the formulas B III and B IV are prefers. Particularly preferred compounds of the formula B III are those of the following subformulae:

wherein
R¹ is CH₃- (CH₂) _n -O-, CH₃- (CH₂) _t -, trans -H- (CH₂) _r -
CH = CH- (CH₂CH₂) _s -CH₂O- or trans-H- (CH₂) _r -
CH = CH- (CH₂CH₂) _s -,
R² CH₃- (CH₂) _t -
n 1, 2, 3 or 4
r 0, 1, 2 or 3
s 0 or 1, and
t is 1, 2, 3 or 4.

Further preferred are those of the partial formula

wherein R¹ and R² have the meaning given above.

The proportion of the compounds of formula B III of the above specified sub-formulas is preferably about 5% to 45%, more preferably about 10% to 35%. Especially preferred compounds of the formula B IV are those the following sub-formula:

wherein
R¹ is CH₃- (CH₂) _n -O- or trans -H- (CH₂) _r -CH = CH- (CH₂CH₂) _s - CH₂O- and R² is CH₃- (CH₂) _t -, where
n 1, 2, 3 or 4,
r 0, 1, 2 or 3,
s 0 or 1, and
t is 1, 2, 3 or 4.

The proportion of these compounds, or the compounds of the formula B IV, is preferably about 5% to 40%, more preferably about 10% to 35%.

Preferably, the mixtures contain compounds of Formula III, especially those of the sub-formula

In a particularly preferred embodiment included the mixtures simultaneously compounds of the formulas B III and B IV, wherein the total content for components of group B1 is maintained.

If compounds of the formulas B I and / or B III present R¹ and R² are preferably each independently each other n-alkyl having 1 to 7 carbon atoms or (trans) - n-alkenyl with 3 to 7 carbon atoms. Z 2 is preferably one Single bond. B I is particularly preferred.

Preference is furthermore given to mixtures according to the invention which contain one or more compounds of the formula B IV, wherein

and R¹ and R² is one of the preferred meanings given above have, in particular preferably n-alkyl having 1 to 7 carbon atoms mean.

In any case, the total percentage of components remains Group B1 respected.  

The proportion of the compounds of group B2 is preferably about 5% to 45%, especially preferred 5% until 20%. The proportion (preferred ranges) for B V to B VII is as follows:

B V about 5% to 30%, preferably about 5% to 15%

Sum B VI and B VII: about 5% to 25%, preferably about 10% to 20%.

Preferred compounds of group B2 are as follows stated:

R¹ is preferably n-alkyl having 1 to 7 carbon atoms or (trans) -n-alkenyl having 3 to 7 carbon atoms. Z⁰ is preferable a single bond. R preferably has the above R¹ denotes preferred meaning or means Fluorine. Y is preferably fluorine.  

Preferably, the mixtures according to the invention contain one or more compounds selected from the group consisting of B V3, B VI1 and B VII1 in a total amount from about 5 to 35%.

In a particularly preferred embodiment included the mixtures according to the invention in addition to B V3, B VI1, B VII1 and B V2 (R = F) other terminal fluorinated compounds for example, selected from the group consisting of:

wherein R¹ is preferably n-alkyl having 1 to 7 carbon atoms or (trans) -n-alkenyl having 3 to 7 C atoms, x 1 or 2, y is 0 or 1 and Y is H or F.  

The total amount of all terminally fluorinated compounds is preferably about 5% to 65%, especially about 15% to 40%.

The proportion of the compounds from group B3 is preferably about 5% to 30%, especially preferably about 10% until 20%. R¹ is preferably n-alkyl or n-alkoxy with each 1 to 9 carbon atoms. R² is preferably n-alkyl with 1 to 9 carbon atoms. However, it can also analog connections used with alkenyl or alkenyloxy groups become. Compounds of formula B VIII are preferred

is preferably 1,4-phenylene.

The mixtures according to the invention contain compounds from at least one of the groups B1, B2 and B3. Preferably contain one or more compounds Group B1 and one or more compounds from group B2 and / or B3.

The proportion of the compounds of component C is preferably about 10% to 80%, especially about 20% to 70%. The expert can to adjust the desired Schwel lens voltage easily adjust this proportion, and in principle All customary liquid crystal compounds with Δε <+1.5 can be used. If predominantly less strong positive terminal fluorinated compounds (see above), the overall proportion moves more in the upper range (about 35% to 80%) while in use of terminal cyano-substituted compounds of the Share may be lower (about 10% to 35%). Especially preferred compounds are in addition to those given above terminal fluorinated compounds the following here mentioned preferred cyano compounds:  

wherein

means.

Some particularly preferred smaller groups are in the following indicated:

R 1 is preferably n-alkyl having 1 to 7 C atoms, n-oxaalkyl having 3 to 7 carbon atoms (eg n-alkoxymethyl) or n-alkenyl having 3-7 C atoms. Y is H or fluorine; x is 1 or 2; y is 0 or 1.

Further preferred are isothiocyanates, e.g. B. the formula

wherein R¹ is n-alkyl having 1 to 7 carbon atoms or n-alkenyl having 3 to 7 carbon atoms.  

In a particularly preferred embodiment included the mixtures according to the invention preferably about 5% to 20% of one or more compounds with one dielectric anisotropy below -1.5 (component D). Such compounds are known, for. B. derivatives of 2,3-Dicyanhydroquinone or cyclohexane derivatives with the structural element

according to DE-OS 32 31 707 and DE-OS 34 07 013.

Preferably, however, compounds with the structure become element selected 2,3-difluoro-1,4-phenylene, z. B. compounds according to DE-OS 38 07 801, 38 07 861, 38 07 863, 38 07 864 or 38 07 908. Particularly preferred are tolans with this Structural element according to the International Patent Application PCE / DE 88/00 133, especially those of the formulas

wherein R¹ and R² are each independently preferably n-alkyl having 1 to 7 carbon atoms or n-alkenyl with 3 to 7 carbon atoms and Z⁰ -CH₂CH₂- or a Single bond is.

The component D causes in particular an improvement the slope of the characteristic.  

In a particularly preferred embodiment included the mixtures about 5% to 35%, particularly preferably about 10% to 20% of liquid-crystalline tolane compounds. As a result, at lower layer thicknesses (approx. 5-6 microns) are worked, whereby the switching times clearly get shorter. Particularly preferred tolans are in following indicated:

R 1 is preferably n-alkyl having 1 to 7 carbon atoms,
Z⁰ is -CH₂CH₂- or a single bond,
Q is

where R² is n-alkyl or n-alkoxy having 1 to 7 carbon atoms or n-alkenyl or n-alkenyloxy, each having 3 to 7 carbon atoms means.

In further particularly preferred embodiments ent keep the blends

• - 30-60% component C, 20-70 wt .-% of compounds Groups A and B, 0-10 wt .-% of component D and a 100% by weight adding amount of the com component E,
• a component D containing one or more compounds with a 1-cyano-trans-1,4-cyclohexylene group or contains a 2,3-difluoro-1,4-phenylene group,  
• at least two compounds of the formula A III or A V,
• Compounds of the formula A III and A V,
• a component C containing one or more compounds with a 4-fluorophenyl group or a Contains 3,4-difluorophenyl group,
• - at least one compound from the following group: wherein alkyl is a straight-chain alkyl group having 2-7 C atoms and X, H or F,
• one or more compounds in which R is a trans- Alkenyl group or a trans-alkenyloxy group,  
• 1- One or more compounds selected from the following group wherein R¹ and R² have the preferred meanings given for component A and one of the two 1,4-phenylene groups may also be substituted by fluorine; the proportion of these compounds is 0% to 25%, preferably about 5% to 15%.

For the component E, the person skilled in the art has a large number of partly commercially available chiral dopants to disposal. Their choice is not critical in itself.

The structure of the liquid crystal display elements according to the invention from polarizers, electrode base plates and Electrodes with such a surface treatment that the preference orientation (director) of each adjacent liquid crystal molecules from one to the other usually up to 160 ° C 360 ° is rotated against each other, which corresponds to such Display elements usual construction. It is the Concept of common construction here broadly conceived and embraced also all literature-known modifications and modifications the supertwist cell, in particular also matrix Display elements and the additional magnets containing Display elements according to DE-OS 27 48 738. The upper Area angle at the two support plates can be the same or be different. Same tilt angles are preferred.  

An essential difference of the invention Display elements to the usual on the basis of However, twisted nematic cell exists in the choice the liquid crystal components of the liquid crystal layer.

The preparation of the liquid used in the invention crystal mixtures is carried out in a conventional manner. Usually, the desired amount is in lesser Quantity of used components in the main component solved components, expedient at elevated Temperature. It is also possible solutions of the components in an organic solvent, e.g. In acetone, Chloroform or methanol, to mix and the solvent after mixing again, for example by distillation.

The dielectrics may also be further known to those skilled in the art and additives described in the literature. at For example, 0-15% pleochroic dyes added become.

The following examples are intended to illustrate the invention, without limiting it.

It means:

SN phase transition temperature smectic-nematic,
Klp. clearing point,
Visc. Viscosity (m Pa · s),
T _on time from switching on until reaching 90% of the maximum contrast
T _off time from switching off to reaching 10% of the maximum contrast

The SFA is controlled in multiplex mode (multiplex ratio) 1: 100, bias 1: 11, operating voltage 18.5 volts).  

Above and below, all temperatures are in ° C give. The percentages are by weight. The values for the switching times and viscosities refer to 20 ° C.

Example 1

An SFA of type OMI with the following parameters:

Twist | 180 ° angle of attack 1 ° d / p (layer thickness / pitch) 0.35 d · Δn 0.5

containing a liquid crystal mixture consisting of

5% p-trans-4-ethylcyclohexylbenzonitrile,
15% p-trans-4-propylcyclohexylbenzonitrile,
11% p-trans-4-butylcyclohexylbenzonitrile,
6% p-trans-4-pentylcyclohexylbenzonitrile,
5% trans-1-p-methoxyphenyl-4-propylcyclohexane,
10% trans, trans-4-ethoxy-4'-pentylcyclohexylcyclohexane,
8% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (5-methylpyridin-2-yl) -ethane,
8% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (5-ethylpyridin-2-yl) -ethane,
8% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (5-propylpyridin-2-yl) -ethane,
8% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (5-pentylpyridin-2-yl) -ethane,
8% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (p-fluorophenyl) -ethane,
8% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (p-cyanophenyl) ethane
and a commercial chiral dopant

shows short switching times.  

example 2

An SFA of type STN with the following parameters:

Twist | 220 ° angle of attack 1 ° d / p 0.5 d · Δn 0.85

containing a liquid crystal mixture consisting of containing a base mixture

15% trans-4-propylcyclohexylbenzonitrile,
11% trans-4-butylcyclohexylbenzonitrile,
4% trans-1-p-methoxyphenyl-4-propylcyclohexane,
14% trans, trans -methoxy-4'-pentylcyclohexylcyclohexane,
14% trans, trans -ethoxy-4'-pentylcyclohexylcyclohexane,
3% 4,4'-bis (trans-4-propylcyclohexyl) biphenyl,
3% 4,4'-bis (trans-4-pentylcyclohexyl) biphenyl,
6% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (5-methylpyridin-2-yl) -ethane,
6% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (5-ethylpyridin-2-yl) -ethane,
6% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (5-propylpyridin-2-yl) -ethane,
6% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (5-pentylpyridin-2-yl) -ethane,
6% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (p-cyanophenyl) ethane,
6% 1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2- (p-fluorophenyl) -ethane

and a suitable chiral component (eg 0.7%). p- (p-n-hexylbenzoyloxy) benzoic acid 2-octyl ester) short switching times.

Claims (13)

1. Supertwist liquid crystal display with

• two plane-parallel carrier plates, which form a cell with a border,
• an in-cell nematic liquid-crystal mixture having positive dielectric anisotropy,
• Electrode layers with overlying orientation layers on the insides of the carrier plates,
• an angle of attack between the longitudinal axis of the molecules on the surface of the carrier plates and the carrier plates of about 1 degree to 30 degrees, and
• a twist angle of the liquid crystal mixture in the cell from orientation layer to orientation layer in the amount between 160 and 360 °, characterized in that the nematic liquid crystal mixture
  • a) at least one component selected from the group A consisting of compounds of the formulas AI to A VI: wherein R¹ and R² are each independently R and
    R is alkyl having 1-12 C atoms, in which also one or two non-adjacent CH₂ groups may be replaced by -O-, -CH = CH-, -CO-, -O-CO- or -CO-O- .
  • b) 0-45% by weight of a component B comprising at least one compound selected from the group B1 consisting of the compounds of the formulas BI to B IV: wherein R¹ and R² each independently of one another have the meaning given for R,
    Z² is -CH₂CH₂-, -CO-O-, -O-CO- or a single bond, and means
    and / or at least one compound selected from the group B2 consisting of the compounds of the formulas BV to B VII: wherein R¹ has the meaning given for R,
    Z⁰ is -CH₂CH₂- or a single bond and means
    where n is 1 to 9, X is CN or F and Y is H or F,
    and / or at least one compound selected from the group B3 consisting of the compounds of the formulas B VIII and B IX: wherein R¹ and R² each independently have the meaning given for R, and means
  • c) 10-80% by weight of a liquid-crystalline component C consisting of one or more compounds having a dielectric anisotropy of more than +1.5,
  • d) 0-20 wt .-% of a liquid-crystalline component D, consisting of one or more compounds having a dielectric anisotropy of less than -1.5 and
  • e) an optically active component E in an amount such that the ratio between layer thickness (spacing of the plane-parallel support plates) and natural pitch of the chiral nematic liquid-crystal mixture is about 0.2 to 1.3, and
• the nematic liquid-crystal mixture has a nematic phase range of at least 60 ° C, a viscosity of not more than 30 mPa · s and a dielectric anisotropy of at least +5, the dielectric anisotropies of the compounds and the parameters relating to the nematic liquid-crystal mixture being at a temperature of 20 ° C are obtained.

2. A display according to claim 1, characterized in that component C contains compounds selected from the group C, consisting of the compounds of the formulas CI to C III: wherein
R has the meaning given in claim 1, means. 3. Display according to at least one of claims 1 and 2, characterized in that the nematic liquid crystal mixture is composed of 30-60 wt .-% Component C, 20-70% by weight of compounds from the groups A and B, 0-10 wt .-% of component D and a to 100 wt .-% adding amount of component E. 4. Display according to at least one of claims 1 to 3, characterized in that component D is an or several compounds with a 1-cyan-trans-1,4- cyclohexylene group or a 2,3-difluoro-1,4-phenylene Group contains. 5. Display according to at least one of claims 1 to 4, characterized in that the nematic liquid crystal mixture at least two compounds of Formula A contains III or A IV. 6. Display according to claim 5, characterized in that the nematic liquid crystal compound compounds of the formula A III and A VI. 7. Display according to at least one of claims 1 to 6, characterized in that the nematic liquid crystal mixture contains compounds of the formula B III. 8. A display according to claim 7, characterized in that the liquid crystal mixture compounds of the formula includes wherein R¹ is CH₃- (CH₂) _n ₂-O- or trans-H- (CH₂) _r - CH = CH- (CH₂CH₂) _s -CH₂-O-
and R² is CH₃- (CH₂) _t -, wherein
n 1, 2, 3 or 4,
r 0, 1, 2 or 3,
s 0 or 1, and
t is 1, 2, 3 or 4. 9. A display according to claim 7 or 8, characterized in that the liquid-crystal mixture compounds of the formulas R¹ is CH₃- (CH₂) _n -O-, CH₃- (CH₂) _t -, trans -H- (CH₂) _r - CH = CH- (CH₂CH₂) _s -CH₂-O-
or trans -H- (CH₂) _r - CH = CH- (CH₂CH₂) _s -, and
R² is CH₃- (CH₂) _t -,
where n, r, s and t have the meaning given in claim 8. 10. Display according to at least one of claims 1 to 9, characterized in that component C is an or several compounds with a 4-fluorophenyl group or a 3,4-difluorophenyl group. 11. A display according to claim 10, characterized in that the liquid-crystal mixture at least one compound from the following group wherein alkyl is a straight-chain alkyl group having 2-7 C atoms and X is H or F. 12. Display according to at least one of claims 1 to 11, characterized in that the liquid-crystal mixture contains one or more compounds, wherein R is a trans-alkenyl group or a trans- Alkenyloxy group is. 13. Nematic liquid-crystal mixture of at least one of claims 1 to 12 defined Composition.