JPH1067988A - Electrooptical liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject display, having a low viscosity and improved in voltage retention ratio and high speed of responsiveness by including a specific liquid crystal medium having a reorienting layer for reorienting a liquid crystal and an electric field thereof having an active component parallel to a liquid crystal layer and a positive dielectric anisotropy. SOLUTION: This electrooptical liquid crystal display comprises a liquid crystal medium having a reorienting layer for reorienting a liquid crystal, an electric field thereof having an active component parallel to a liquid crystal layer and further a positive dielectric anisotropy. The modium contains (A) one or more mesogen compounds having 3,4-difuorophenyl group and (B) one of more mesogen compounds represented by the formula [R<1> and R<2> are each a 1-12C alkyl or an alkenyl which may have CN or CF3 as a substituent group; A<1> and A<2> are each trans-1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, piperidine-1,4-diyl, etc.; Z<1> is CO-O, CH2 O, CH=CH, etc.; (m) is 1-3].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention comprises a liquid crystal medium having a positive dielectric anisotropy having a reorientation layer for reorienting a liquid crystal having an effective component whose electric field is parallel to the liquid crystal layer. The present invention relates to an electro-optical liquid crystal display. The invention also relates to such a liquid crystal medium.

[0002]

2. Description of the Related Art Conventional liquid crystal displays (TN, ST)
In N, OMI and AMD-TN), the electric field for reorientation occurs substantially perpendicular to the liquid crystal layer. International patent application WO 91/10936 describes a liquid crystal display in which the electric signal is generated in such a way that the electric field has an active component parallel to the liquid crystal layer [IP
S, In-Plane Switchi
ng)]. The principle of operation of such a display is, for example,
Journal of Applied Physics, Vol. 45, N by RASoref
o, 12, 5466-5468 (1974). EP 0 58
8 568 discloses various addressing methods for such displays.

[0003] These IPS displays can be operated using liquid crystal materials having either positive or negative dielectric anisotropy (△ ε ≠ 0). Conventionally known materials having a large dielectric anisotropy value are obtained in principle by using liquid crystals having terminal cyano groups. However, these compounds have an adverse effect on the resistance and voltage holding ratio of the IPS display element. Furthermore, the use of large proportions of polar compounds results in undesired viscosity values and large birefringence values, and these properties are not preferred in many applications. Therefore,
In IPS displays, the problem was to identify liquid crystal materials suitable for achieving relatively high voltage holding ratios, low birefringence values and low viscosities and short response times.

[0004]

The problem to be solved by the present invention is that
The object is to find a liquid crystal material suitable for achieving a relatively high voltage holding ratio, a small birefringence value, a low viscosity and a short response time in an S display. Another object of the present invention is to find a liquid crystal material useful for producing such a liquid crystal medium.

[0005]

Surprisingly, the object is to provide a liquid crystal material comprising at least one compound containing a 3,4-difluorophenyl group and at least one mesogen compound of the formula I Is achieved by using Compounds of this kind are, for example, EP 0
132 553, DE 26 36 684, EP 0 258 868 and DE 30 42
391. However, these publications do not mention that the use of these substances can improve the voltage holding ratio and response time of IPS displays. The present invention relates to an electro-optical liquid crystal having a reorientation layer for reorienting a liquid crystal having an effective component whose electric field is parallel to the liquid crystal layer, and further comprising a liquid crystal medium having a positive dielectric anisotropy. A display, wherein the medium comprises at least one mesogenic compound having a 3,4-difluorophenyl group and a compound of formula I:

R ^1- (A ¹ -Z ¹ ) _m -A ² -R ² (I) wherein R ¹ and R ² are each independently of the other an alkyl group having 1 to 12 carbon atoms or An alkenyl group, which is unsubstituted, has one CN or CF ₃ as a substituent, or has at least one halogen as a substituent and is present in these groups. The one or more CH ₂ groups which are also each independently of one another are such that the O atoms are not directly bonded to each other:

Embedded image May be replaced by -O-CO-O-,

A ¹ and A ² are each independently of the other
(A) a trans-1,4-cyclohexylene group or a 1,4-cyclohexenylene group, in which one CH ₂ group or two or more non-adjacent C 2 groups
H ₂ group also, -O- and (or) -S- may be replaced by, (b) 1,4-phenylene group, one or two CH groups present in this group May also be replaced by N, (c) 1,
4-bicyclo [2.2.2] octylene, piperidine-
1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4
A group from the group consisting of -tetrahydronaphthalene-2,6-diyl, wherein said groups (a) and (b) may have one or two fluorine atoms as substituents,

Z ¹ is -CO-O-, -O-CO-,-
_{CH 2 O -, - OCH 2} -, - CH 2 CH 2 -, - CH = C
H—, —C≡C— or a single bond, or Z ¹ is also — (CH ₂ ) ₄ — or —CH ＝ CH—CH ₂ CH ₂
And m is 1, 2 or 3 is an electro-optical liquid crystal display containing at least one mesogenic compound of the formula

In a preferred embodiment there is provided an IPS display whose liquid crystal medium is: a) the medium contains at least one compound of the formula I and at least one of the compounds of the formula II Do:

Embedded image

Wherein R ³ is as defined for R ¹ and R ² , and A ³ and A ⁴ are each independently of the other as defined for A ¹ and A ² , Z ² and Z ³ are each independently of the other
^As defined for ¹ and n is
0, 1 or 2;

B) the medium contains at least one compound of the formula III:

Embedded image Wherein R ⁴ is as defined for R ¹ , A ⁵ and A ⁶ are each independently of the other, as defined for A ¹ and A ² , Z ⁴ and Z ⁵ Are each independently of the other as defined for Z ¹ , and o is 0, 1 or 2;

C) the medium contains at least one compound of the formula IV:

Embedded image Wherein R ⁵ is as defined for R ¹ , A ⁷ and A ⁸ are each independently of the other, as defined for A ¹ and A ² , Z ⁶ and Z ⁷ Are each, independently of ^{one another} , as defined for Z ¹ , L ¹ and L ² are each independently of each other, H or F;

[0013] Q is the formula _{- (O) q - (CH} 2) r - (CF 2) s - ( wherein, q is 0 or 1, r is an integer of 0 or 1-6, and s is an integer of 1 to 6), and X is H, F
Or Cl, and p is 0, 1 or 2;

D) the medium contains cyano group-containing liquid crystals in an amount of at most 20%; e) the medium comprises at least one compound of the formula V
Contains seeds:

Embedded image Wherein Hal is F or Cl, and R ⁶ is as defined for R ¹ . A further preferred embodiment is an IPS display whose pixels are addressed by an active matrix.

The present invention also relates to a positive dielectric anisotropic compound containing a compound having a 3,4-difluorophenyl group, preferably at least one compound of the formula II and at least one compound of the formula I. Liquid crystal media having properties, in particular liquid crystal media having the following composition: at least one compound of the formula I
% By weight, preferably 5 to 30% by weight, at least one compound of the formula II
60% by weight, preferably 10 to 50% by weight, at least one compound of the formula III
50% by weight, preferably 5-30% by weight, at least one compound of the formula IV
0% by weight, preferably 10-30% by weight, and at least one compound of the formula V
% By weight, preferably 5 to 15% by weight.

The novel liquid-crystal medium according to the invention is preferably
Contains the following compounds: at least one of the compounds selected from the following formulas IIa and IIb:

Embedded image

The following formulas IIIa, IIIb and III:
at least one compound selected from c:

Embedded image

At least one compound selected from the following formulas Ia, Ib and Ic:

Embedded image

And-optionally, at least one compound selected from the formulas IVa and IVb:

Embedded image

If desired, at least one compound of the formula Va:

Embedded image In each of the above equations,

Embedded image And R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , L ¹ and L ² are each as defined above.

In a particularly preferred embodiment, the novel medium according to the invention comprises at least one of the compounds of the formula IIa
Contains seeds. In a still further preferred embodiment, the novel medium according to the invention contains at least one compound of the formula IIa and at least one compound of the formula Ia. Furthermore, media containing at least one of the compounds of the formula IIIc are also preferred. A particularly preferred embodiment is a medium containing cyano group-containing liquid crystals in an amount not more than 20%, preferably 0-5%.

The novel liquid-crystal media according to the invention generally have the form <
0.12, preferably 0.06-0.1, especially 0.06
It has a birefringence index Δn of ０．０0.08. The kinematic viscosity (at 20 ° C.) of the novel materials according to the invention is generally 30 mm ²
/ Sec, especially 10 to 25 mm ² / sec.
The resistance of the new material according to the invention is 5 × at 20 ° C.
10 ^{10 to} 5 × 10 ¹³ Ω · cm, particularly preferably 5 × 10
^{It is 11 to} 7 × 10 ¹² Ω · cm. Even if the compounds of the formula II are present in a mixture with conventional liquid-crystal materials in relatively small proportions, it is especially advantageous to use one or two of the compounds of the formulas I, III and / or IV The presence of more than one species greatly increases retention and increases response time, while at the same time reducing smecticity.
It has been found that a wide range of nematic phases with a nematic transition temperature is found.

In particular, by using the compounds of the formula I, the viscosity and the birefringence can be reduced, which is advantageous for certain applications. Formula I ~
The compounds represented by IV are colorless, stable and also readily miscible with each other and with other liquid crystal materials.
The term "alkyl" embraces straight-chain and branched alkyl groups having 1-7 carbon atoms, in particular the straight-chain groups methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl. Include. Side groups having 2 to 5 carbon atoms are generally preferred.

The term "alkenyl" refers to a group consisting of 2 to 7 carbon atoms.
And straight-chain and branched alkenyl groups, especially straight-chain groups. Certain alkenyl groups include C _2-
C _{7-1E-alkenyl,} C ₄ -C ₇ -3E-alkenyl, C ₅ -C _7-4-alkenyl, C ₆ -C _7-5-alkenyl and C _7-6-alkenyl, in particular C ₂ -C ₇ -1E
- alkenyl, C ₄ ~C ₇ -3E- alkenyl and C ₅
~C ₇ -4- there is alkenyl. Examples of suitable alkenyl include vinyl, 1E-propenyl, 1E-butenyl, 1E
-Pentenyl, 1E-hexenyl, 1E-heptenyl,
3-butenyl, 3E-pentenyl, 3E-hexenyl,
Examples include 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like. Groups having up to 5 carbon atoms are generally preferred.

The term "fluoroalkyl" preferably refers to linear groups having a terminal fluorine atom, ie, fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluoropentyl,
Includes fluorohexyl and 7-fluoroheptyl. However, fluorine atoms at other positions are not excluded. The term "oxaalkyl" is preferably of the formula C _y H
_2y + 1 -O- (CH ₂₎ straight-chain groups (wherein represented by _z, y
And z are each independently of the other 1-6). y is preferably 1 and z is preferably 1-6.

By appropriately selecting the meanings of R ^{1 to} R ⁶ , the address time, the threshold voltage, the steepness of the transmission characteristic curve, and the like can be modified as desired. For example, 1E-alkenyl group, 3E-alkenyl group, 2E-
Alkenyloxy groups and the like generally have shorter addressing times, improved tendency to form nematic phases and elastic constants k ₃₃ (bend) compared to alkyl and alkoxy groups.
And a large ratio of k ₁₁ (spread). 4-Alkenyl radicals, generally 3-alkenyl radicals and the like compared with alkyl and alkoxy groups, give lower threshold voltages and smaller values of k ₃₃ / k _11.

The —CH ₂ CH ₂ — group in Z ¹ or Z ² generally results in a large k ₃₃ / k ₁₁ value compared to a single covalent bond. Larger values of k ₃₃ / k ₁₁ result in a flatter transmission characteristic curve in TN cells with a twist angle of eg 90 ° (to obtain a halftone) and also a higher S
In TN, SBE and OMI cells, which have greater multiplexability, a steeper transmission characteristic curve results, and vice versa.
The optimum mixing ratio of the compound of the formula I to the compound of the formula II + the compound of the formula III + the compound of the formula IV + the compound of the formula V (ie
Formula I / Formula II + Formula III + Formula IV + Formula V) is substantially dependent on the desired properties, the selection of the components of Formulas I, II, III, IV and / or V, and the selection of any other components present. Depends on Suitable mixing ratios within the specific range can be easily determined in some cases.

The total amount of the compounds of the formulas IV in the novel mixtures according to the invention is not restricted. Thus, these mixtures can contain one or more additional components, which can optimize various properties. However, the effects found on retention, addressing time and threshold voltage generally increase with higher total concentrations of the compounds of formulas II and III. The effect found on viscosity and birefringence generally increases with increasing total concentration of the compound of formula I. In a particularly preferred embodiment, the novel medium according to the invention comprises a compound of formula IV (preferably of formula I and / or
In I), containing a compound Q-X is OCF ₃ or OCHF _2. The favorable synergistic effect with the compounds of the formula II results in particularly advantageous properties.

The novel liquid-crystal medium according to the invention is preferably
In addition to one or more of the compounds of the formulas I, II, III, IV and V, 2 to 40, in particular 4 to 30, components are contained as additional components.
These media particularly preferably contain 7 to 25 components in addition to one or more of the novel compounds. These additional components are preferably nematic or nematic phase-forming (monotropic or isotropic) substances, in particular azoxybenzene compounds, benzylideneaniline compounds, biphenyl compounds, terphenyl compounds, phenyl or cyclohexyl benzoate compounds, Phenyl or cyclohexyl ester compound of cyclohexanecarboxylic acid, phenyl or cyclohexyl ester compound of cyclohexylbenzoic acid,
Phenyl or cyclohexyl ester compound of cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl ester compound of benzoic acid, cyclohexylphenyl ester compound of cyclohexanecarboxylic acid, cyclohexylphenyl ester compound of cyclohexylcyclohexanecarboxylic acid,

Phenylcyclohexane compound, cyclohexylbiphenyl compound, phenylcyclohexylcyclohexane compound, cyclohexylcyclohexane compound, cyclohexylcyclohexylcyclohexene compound, 1,4-biscyclohexylbenzene compound,
4'-biscyclohexylbiphenyl compound, phenyl- or cyclohexylpyrimidine compound, phenyl-
Or cyclohexylpyridine compound, phenyl- or cyclohexyldioxane compound, phenyl- or cyclohexyl-1,3-dithiane compound, 1,2-diphenyl-ethane compound, 1,2-dicyclohexylethane compound, 1-phenyl-2-cyclohexylethane compound , 1-cyclohexyl-2- (4-phenylcyclohexyl) ethane compound, 1-cyclohexyl-2-
It is selected from the group consisting of biphenylylethane compounds, 1-phenyl-2-cyclohexyl-phenylethane compounds, optionally halogenated stilbene compounds, benzylphenyl ether compounds, tolan compounds and substituted cinnamic acid compounds. The 1,4-phenylene groups present in these compounds may also be fluorinated.

The most important compounds which are suitable as additional components of the novel medium can be characterized by the following formulas 1, 2, 3, 4 and 5: R′-L-E-R ″ 1 R′- L-COO-E-R'' 2 R'-L-OOC-E-R'' 3 R'-L-CH 2 CH 2 -E-R'' 4 R'-L-C≡C-E- R '' 5

In the formulas 1, 2, 3, 4 and 5, L and E may be the same or different and are each independently of the other -Phe-, -Cyc-, -Phe-Ph
e-, -Phe-Cyc-, -Cyc-Cyc-, -P
yr-, -Dio-, -G-Phe- and -G-Cy
divalent groups from the group formed from c- and their mirror image groups, in which Phe is unsubstituted,
Or fluorine-substituted 1,4-phenylene, Cyc is trans-1,4-cyclohexylene or 1,4-cyclohexenylene, and Pyr is pyrimidine-2,5-diyl or pyridine-2,5. -Diyl, Dio is 1,3-dioxane-2,5-diyl, and G is 2- (trans-1,4-cyclohexyl) ethyl, pyrimidine-2,5-diyl, pyridine-2,5 -Diyl or 1,3-dioxane-2,5
-Jiyl.

One of the groups L and E is preferably Cyc, Phe or Pyr. E is preferably
Cyc, Phe or Phe-Cyc. The new medium is preferably in formulas 1, 2, 3, 4 and 5
And one or more components selected from compounds wherein E is selected from the group consisting of Cyc, Phe and Pyr, and simultaneously, in formulas 1, 2, 3, 4 and 5, of the groups L and E One is selected from the group consisting of Cyc, Phe and Pyr, and the other group is -Phe-P
he-, -Phe-Cyc-, -Cyc-Cyc-,-
One or more components selected from compounds selected from the group consisting of G-Phe- and -G-Cyc-,
And also optionally, in formulas 1, 2, 3, 4 and 5, the groups L and E are -Phe-Cyc-, -Cyc-C
It contains one or more components selected from compounds selected from the group consisting of yc-, -G-Phe- and -G-Cyc-.

In a narrow sub-group of the compounds of the formulas 1, 2, 3, 4 and 5, R 'and R "are each independently of the other alkyl, alkenyl, alkoxy having up to 8 carbon atoms. , Alkoxyalkyl, alkenyloxy or alkanoyloxy. This narrow sub-group is referred to below as Group A and these compounds are identified by sub-formulae 1a, 2a, 3a, 4a and 5a. In most of these compounds, R 'and R'
'Are different from each other and one of these groups is usually alkyl, alkenyl, alkoxy or alkoxyalkyl.

Another narrow subgroup of compounds of the formulas 1, 2, 3, 4 and 5 is known as group B, in which R '' is -F,-
Cl, -NCS or _{- (O) i CH 3- (} k + 1) is F _k Cl ₁ (here, i is 0 or 1, and k + l is 1, 2 or 3). Compounds in which R ″ has this meaning are identified by appendixes 1b, 2b, 3b, 4b and 5b. In the compounds represented by the attached formulas 1b, 2b, 3b, 4b, and 5b, R ″ represents —F, —Cl, —NC
S, -CF _3, compound is -OCHF ₂ or -OCF ₃ may be mentioned as particularly preferred compounds.

Appendices 1b, 2b, 3b, 4b and 5b
In the compound represented by the formula, R ′ is a compound represented by the following formulas 1a to 5a:
As defined for the compound of formula (I), preferably alkyl, alkenyl, alkoxy or alkoxyalkyl. In yet another narrow sub-group of compounds of formulas 1, 2, 3, 4 and 5, R "is -CN. This sub-group is known below as Group C, and the compounds of this sub-group are correspondingly represented by sub-formulae 1c, 2c, 3c, 4c and 5c. The attached formulas 1c, 2c, 3c, 4c and 5c
In the compound represented by the formula, R ′ is a compound represented by the following formulas 1a to 5a:
And is preferably an alkyl, alkoxy or alkenyl.

In addition to the preferred compounds of groups A, B and C, the compounds of formula 1, with various other proposed substituents,
Other compounds represented by 2, 3, 4 and 5 are also conventional. All of these substances can be obtained by known methods or similar methods from publications. The novel medium preferably contains, in addition to the novel compound of the formula I, one or more compounds selected from group A and / or group B and / or group C. The proportion by weight of compounds from these groups present in the novel medium according to the invention is preferably as follows: Group A: 0-90%, preferably 20-90%, especially 30-90%, Group B: 0-80%, preferably 10-80%, especially 10-65%, Group C: 0-10%, preferably 0-5%, especially 0
~ 2%.

Group A and / or Group B and / or Group C present in a particular new medium
Is preferably 5% to 90%.
%, Especially 10% to 90%. The novel medium preferably contains 1 to 40% of the novel compound, particularly preferably 5 to 30%.
%. Further preferred media contain the novel compounds in a proportion of more than 40%, in particular in a proportion of 45 to 90%. The medium preferably contains three, four or five new compounds. New IPS according to the present invention
The structure of the display is, for example, WO 91/10936 or EP 0 5
It corresponds to a structure customary for this type of display, as described in 88 568. Here, the term conventional construction is to be interpreted broadly, and all of the inductive and modified IPS displays, especially for example poly-Si, T
Includes matrix display elements based on FT or MIM.

However, the fundamental difference between the new display according to the invention and the conventional display is the choice of the liquid crystal parameters of the liquid crystal layer. The liquid-crystal mixtures which can be used according to the invention can be prepared by methods customary per se. In general, the desired amount of the components used in the smaller amounts is dissolved in the components making up the main component, advantageously at elevated temperature. After mixing the solution of the components in an organic solvent, for example acetone, chloroform or methanol, and then thoroughly mixing,
The solvent can again be separated off, for example by distillation.
The dielectric may also contain additional additives known to those skilled in the art and described in the publication. For example,
0-15% of polychromatic dyes or chiral dopants can be added.

[0040] C denotes a crystalline phase, S a smectic phase, S _B a smectic B phase, N a nematic phase and I the isotropic phase. V ₁₀ denotes the voltage for 10% transmission (visual direction perpendicular to the substrate surface). t _on is switched at an operating voltage corresponding to 2.5 times the value of V ₁₀ - represents the on time and t _off are switched - represents the off time. △ n denotes the optical anisotropy and n ₀ represents the refractive index (at 589nm in both). Δε is the dielectric anisotropy (△ ε = ε‖−ε⊥, where ε‖ represents the permittivity parallel to the long axis of the molecule, and ε⊥ is perpendicular to the long axis of the molecule) Represents the dielectric constant). Optical data was measured at 20 ° C. unless otherwise noted.

A planar test cell having a twist angle of 0 ° and a tilt angle of 0 ° was used. In this patent application and in the examples below, the structure of the liquid crystal compound is indicated by an acronym, and its conversion into a chemical formula is obtained according to Tables A and B below. The radicals C _n H _{2n + 1} or C _m H _{2m + 1} are all straight-chain alkyl radicals having n or m carbon atoms.
n and m are each independently 1-12. The codes in Table B are self-evident. In Table A, only the initials related to the parent structure (basic structure) are shown. In each case, after the acronym for this parent structure, the codes for the substituents R ¹ , R ² , L ¹ and L ² are shown separated by a hyphen:

[0042]

[Table 1]

Table A :

Embedded image

Table B :

Embedded image

Without further elaboration, it is believed that one skilled in the art can, using the above description, utilize the broadest scope. Accordingly, the preferred embodiments are merely illustrative, and are not to be construed in any way as limiting the invention.

[0046]

IPS display EXAMPLES Example 1 This example, clearing point + 84 ℃ △ n (589nm, 20 ℃) 0.0792 n o 1.4768 △ ε (1kHz, 20 ℃) +7.6 rotational viscosity gamma ₁ [mPa .S] 103 K ₃ / K ₁ 1.79 and also

[0047]

[Table 2]

And has a large contrast and a short response time.

 ──────────────────────────────────────────────────続 き Continuation of front page (71) Applicant 591032596 Frankfurter Str. 250, D-64293 Darmstadt, Federal Republic of Germany (72) Inventor Kazuaki Talmi, Germany Day-64293 Darmstadt Frankfurter Strasse 250 (72) Inventor Andreas Beyer, Germany Day-64293 Darm Stadt Frankfurter Straße 250

Claims (10)

[Claims] 1. A liquid crystal medium having a reorientation layer for reorienting a liquid crystal, an electric field having an active component parallel to the liquid crystal layer, and a liquid crystal medium having a positive dielectric anisotropy. An electro-optical liquid crystal display, wherein the medium is (A) at least one mesogenic compound having a 3,4-difluorophenyl group and (B) a formula I: R ^1- (A ¹ -Z ¹ ) _m- A ² —R ² I wherein R ¹ and R ² are each independently of the other an alkyl or alkenyl group having 1 to 12 carbon atoms, which is unsubstituted or substituted Has one CN or CF ₃ as a substituent, or has at least one halogen as a substituent, and one or more CH ₂ groups present in these groups are also mutually independent of each other. O atoms are directly bonded to each other As there is not, -O-CO-O- may be replaced by
¹ and A ² are each independently (a) a trans-1,4-cyclohexylene group or a 1,4-cyclohexenylene group, and one CH ₂ present in this group is
The group or two or more CH ₂ groups that are not adjacent are also —
(B) a 1,4-phenylene group, wherein one or two CH groups present in this group may also be replaced by N (C) 1,4-bicyclo [2.2.2] octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1, A group from the group consisting of 2,3,4-tetrahydronaphthalene-2,6-diyl, wherein the groups (a) and (b) have one or two fluorine atoms as substituents, Z ¹ is −
CO-O -, - O- CO -, - CH 2 O -, - OCH
_{2 -, - CH 2 CH 2} -, - CH = CH -, - C C- or a single bond, or Z ¹ can also, - (CH _{2) 4}
- or _{-CH = CH-CH 2 CH 2} - it can be, and m is characterized by containing at least one, 1, 2 or 3, in represented by mesogenic compounds, wherein Electro-optical liquid crystal display. 2. The method according to claim 1, wherein the medium is of the formula II: Wherein R ³ is as defined for R ¹ , and A ³ and A ⁴ are each independently of the other A ¹ and A ²
Z ² and Z ³ are each, independently of ^{one another} , as defined for Z ¹ , and n is 0, 1 or 2 The liquid crystal display according to claim 1, wherein the liquid crystal display contains at least one kind. 3. The medium of formula III: Wherein R ⁴ is as defined for R ¹ , and A ⁵ and A ⁶ are each independently of the other A ¹ and A ²
Z ⁴ and Z ⁵ are each independently of the other Z ¹ and Z ²
And o is as defined for
3. The composition according to claim 1, further comprising at least one compound represented by formula (1).
A liquid crystal display according to any one of the above. 4. The medium of formula IV: Wherein R ⁵ is as defined for R ¹ , and A ⁷ and A ⁸ are each independently of the other A ¹ and A ²
And Z ⁶ and Z ⁷ are each independently of the other, as defined for Z ¹ , and L ¹ and L ² are each independently of each other, H or F There, Q is the formula _{- (O) q - (CH} 2) r - (CF 2) s - ( wherein, q is 0 or 1, r is an integer of 0 or 1 to 6, and s Is an integer of 1 to 6), wherein X is H, F or Cl, and p is 0, 1 or 2. The liquid crystal display according to any one of claims 1 to 3, further comprising: 5. The method according to claim 1, wherein the medium is of the formula V: Wherein R ⁶ is as defined for R ¹ , and Hal is F or Cl, containing at least one of the compounds represented by the formulas: A liquid crystal display according to any one of the above. 6. The method according to claim 1, wherein the medium contains the cyano group-containing liquid crystal compound in an amount not more than 20%.
6. The liquid crystal display according to any one of items 1 to 5, 7. A liquid crystal display according to claim 1, wherein the pixels are addressed by an active matrix. 8. A liquid crystal medium having a positive dielectric anisotropy, comprising the composition according to claim 1. 9 to 5% by weight, preferably 5 to 30% by weight, of at least one compound of the formula I; 10 to 10% by weight of the at least one compound of the formula II;
60% by weight, preferably 10 to 50% by weight, at least one compound of the formula III
50% by weight, preferably 5-30% by weight, at least one compound of the formula IV
0% by weight, preferably 10-30% by weight, and at least one compound of the formula V
The liquid crystal medium according to claim 8, characterized in that it contains about 5% by weight, preferably 5 to 15% by weight. 10. At least one compound selected from the following formulas IIa and IIb: At least one compound selected from the following formulas IIIa, IIIb and IIIc: At least one compound selected from the following formulas Ia, Ib and Ic: And optionally at least one compound selected from formulas IVa and IVb below: Optionally, at least one compound of formula Va: (In each of the above formulas, And R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , L ¹ and L ² are each as defined in claims 1 to 5). , Claim 6 or 9
A liquid crystal medium according to any one of the above.