Electro-optical liquid crystal display

• US 5,993,691 A
• Filed: 08/04/1997
• Issued: 11/30/1999
• Est. Priority Date: 02/03/1995
• Status: Expired due to Term

• Current Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Original Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Poetsch, Eike, Reiffenrath, Volker, Schuler, Brigitte, Tarumi, Kazuaki, Bremer, Matthias, Wachtler, Andreas, Huth, Anja, Kompter, Michael, Beyer, Andreas, Pausch, Axel
• Primary Examiner(s): KELLY, CYNTHIA HARRIS
• Application Number:
  US08/875,745
• Time in Patent Office: 848 Days
• Field of Search: 252/299.63, 252/299.67, 252/299.61, 252/299.66, 349/182, 349/123
• US Class Current: 252/299.63
• CPC Class Codes: C09K 19/0403 the structure containing one or more specific, optionally substituted ring or ring systems
• CPC Class Codes: C09K 19/3001 Cyclohexane rings
• CPC Class Codes: C09K 19/42 Mixtures of liquid crystal compounds covered by two or more of the preceding groups C09K19/06 - C09K19/40
• CPC Class Codes: C09K 19/46 containing esters
• CPC Class Codes: C09K 2019/0407 containing a carbocyclic ring, e.g. dicyano-benzene, chlorofluoro-benzene or cyclohexanone
• CPC Class Codes: C09K 2019/0414 containing a heterocyclic ring

Abstract

The invention relates to an electro-optical liquid-crystal display having a realignment layer for realigning the liquid crystals whose field has a significant component parallel to the liquid-crystal layer and which contains a liquid-crystalline medium of positive dielectric anisotropy, where the medium comprises at least one mesogenic compound containing a 3,4,5-trifluorophenyl group and/or comprises at least one mesogenic compound [lacuna] a structural unit of the formula 2 ##STR1## in which A is O or CH,

z is --COO-- or a single bond

L¹ is F or, if A is O, is alternatively H, and

L² is H or F.

Claims

1. Electro-optical liquid crystal display

having a realignment layer for realigning the liquid crystals whose field has a component parallel to the liquid crystal layer sufficient for leading to in-plane switching,

and which contains a liquid crystalline medium of positive dielectric anisotropy, characterized in that the medium comprises at least one compound of the formula Ia ##STR38## and at least one compound of formula Ib ##STR39## in which ##STR40## is in each case ##STR41## and R¹ is H, an alkyl or alkenyl radical having 1 to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF₃ or at least monosubstituted by halogen, where one or more CH₂ groups in these radicals may also, in each case independently of one another, be replaced by --O--, --S--, --CO--, --CO--O--, --O--CO-- or --O--CO-- in such a way, that O-atoms are not linked directly to one another,

and at lease one compound of formula II ##STR42## in which L³ and L⁴ are each H or F,

R² is as defined for R¹, and

A³ and A⁴ are each, independently of one another, a

a) trans-1,4-cyclohexylene radical or 1,4-cyclohexenylene radical, in which, in addition, one or more non-adjacent CH₂ groups may be replaced by --O-- and/or --S--,

b) 1,4-phenylene radical, in which, in addition, one or two CH groups may be replaced by N,

c) radical from the group consisting of 1,4-dicyclo(2,2,2)octylene, piperidine-1,4-diyl,naphthaline-2,6-diyl, decahydronaphthaline-2,6-diyl and 1,2,3,4-tetrahydronaphthaline-2,6-diyl,

where the radicals (a) and (b) may be substituted by one or two fluorine atoms,

Z³ and Z⁴ are each, independently of one another, --CO--O--, --O--CO--, --CH₂ O, --OCH₂ --, --CH₂ CH₂ --, --CH═

CH₂ --C.tbd.C--, or a single bond, or one of the radicals Z³ and Z⁴ is --(CH₂)₄ -- or --CH═

CH--CH₂ CH₂ --, and

n is 0, 1 or 2.

2. Display according to claim 1, characterized in that the medium comprises at least two compounds of formula Ia.

3. Display according to claim 1, characterized in that the medium comprises at least three compounds of formula Ia.

4. Display according to claim 1, characterized in that the medium comprises at least two compounds of formula Ib.

5. Display according to claim 1, characterized in that the medium comprises at least three compounds of formula Ib.

6. Display according to claim 2, characterized in that the medium comprises at least two compounds of formula Ib.

7. Display according to claim 3, characterized in that the medium comprises at least three compounds of formula Ib.

8. Display according to claim 1 characterized in that the medium contains at least one compound of formula Ia in which ##STR43##

9. Display according to claim 1 characterized in that the medium contains at least one compound of formula Ia in which and at least one compound of the formula Ia in which ##STR44##10.

10. Display according to claim 1 characterized in that the medium contains at least one compound of formula Ib in which

11. Display according to claim 9 characterized in that the medium contains at least one compound of formula Ib in which

12. Liquid-crystal display according to claim 1, characterized in that the medium comprises at least one compound of the formula II in which R² A³, A⁴, Z³, Z⁴ and n are as defined above, L³ is F, and

L⁴ is H or F.

13. Liquid-crystal display according to claim 1, characterized in that the medium comprises at least one compound selected from the formulae IIa to IIc ##STR45## in which R², L³ and L⁴ are in each case as defined claim 1.

14. Liquid-crystal display according to claim 1, characterized in that the medium has a dielectric anisotropy Δ

ε

of >

8.5.

15. Liquid-crystal display according to claim 1, characterized in that the medium comprises at least one compound of the formula III

16. Liquid-crystal display according to claim 1, characterized in that the medium comprises at least one compound of the formula IV ##STR46## in which R⁵ is as defined for R¹,

A⁷ and A⁸ are each, independently of one another, as defined for A³ and A⁴,

Z⁷ and Z⁸ are each, independently of one another, as defined for Z³ and Z⁴,

L⁵ and L⁶ are each, independently of one another, H or F,

Q is a polyfluoroalkylene radical of the formula

17. Display according to claim 1, characterized in that the pixels within the display are addressed by means of an active matrix.

18. Liquid crystalline medium of positive dielectric anisotropy, characterized in that the medium comprises at least one compound of the formula Ia ##STR47## and at least one compound of formula Ib ##STR48## and R¹ is H, an alkyl or alkenyl radical having 1 to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF₃ or at least monosubstituted by halogen, where one or more CH₂ groups in these radicals may also, in each case independently of one another, be replaced by --O--, --S--, --CO--, --CO--O--, --O--CO-- or --O--CO-- in such a way, that O-atoms are nor linked directly to one another,

and at lease one compound of formula II ##STR49## in which L³ and L⁴ are each H or F,

R² is as defined for R¹, and

A³ and A⁴ are each, independently of one another, a

a) trans-1,4-cyclohexylene radical or 1,4-cyclohexenylene radical, in which, in addition, one or more non-adjacent CH₂ groups may be replaced by --O-- and/or --S--,

b) 1,4-phenylene radical, in which, in addition, one or two CH groups may be replaced by N,

c) radical from the group consisting of 1,4-dicyclo(2,2,2)octylene, piperidine-1,4-diyl, naphthaline-2,6-diyl, decahydronaphthaline-2,6-diyl and 1,2,3,4-Tetrahydronaphthaline-2,6-diyl,

where the radicals (a) and (b) may be substituted by one or two fluorine atoms,

Z³ and Z⁴ are each, independently of one another, --CO--O--, --O--CO--, --CH₂ O, --OCH2--, --CH₂ CH₂ --, --CH═

CH, --C.tbd.C--, or a single bond, or one of the radicals Z³ and Z⁴ is --(CH₂)₄ -- or --CH═

CH--CH₂ CH₂ --, and

n is 0, 1 or 2.

19. A liquid crystalline medium according to claim 18, characterized in that the medium comprises at least two compounds of formula Ia.

20. A liquid crystalline medium according to claim 18, characterized in that the medium comprises at least three compounds of formula Ia.

21. A liquid crystalline medium according to claim 18, characterized in that the medium comprises at least two compounds of formula Ib.

22. A liquid crystalline medium according to claim 18, characterized in that the medium comprises at least three compounds of formula Ib.

23. A liquid crystalline medium according to claim 18 characterized in that the medium contains at least one compound of formula Ia in which ##STR50##

24. A liquid crystalline medium according to claim 18 characterized in that the medium contains at least one compound of formula Ia in which and at least one compound of the formula Ia in which ##STR51##

25. A liquid crystalline medium according to claim 18 characterized in that the medium contains at least one compound of formula Ib in which

26. A liquid crystalline medium according to claim 18, characterized in that the medium comprises at least one compound of the formula II in which R^z, A³, A⁴, Z³, Z⁴ and n are as defined in claim 18, L³ is F, and

L⁴ is H or F.

27. A liquid crystalline medium according to claim 18, characterized in that the medium comprises at least one compound selected from the formulae IIa to IIc ##STR52## in which R², L³ and L⁴ are in each case as defined in claim 18.

28. A liquid crystalline medium according to claim 18 having a dielectric anisotropy Δ

ε

of >

8.5.

29. A liquid crystalline medium according to claim 18 comprising at least one compound of the formula III

R³ --(A⁵ --Z⁵)_o -A⁶ --R⁴

in which

R³ and R⁴ are each, independently of one another as defined for R¹,

A⁵ and A⁶ are each, independently of one another, as defined for A³ and A⁴,

Z⁵ is in each case, independently of the others, as defined for Z³ and Z⁴, and

o is 1, 2 or 3.

30. A liquid crystalline medium according to claim 18, characterized in that the medium comprises at least one compound of the formula IV ##STR53## in which R⁵ is as defined for R¹,

A⁷ and A⁸ are each, independently of one another, as defined for A³ and A⁴,

Z⁷ and Z⁸ are each, independently of one another, as defined for Z³ and Z⁴,

L³ and L^o are each, independently of one another, H or F,

Q is a polyfluoroalkylene radical of the formula

31. A liquid crystalline medium characterized in that it comprises

from 10 to 60% by weight, of at least one compound of the formula I, ##STR54## from 15 to 40% by weight, of at least one compound of the formula II of claim 18,

from 20 to 55% by weight, of at least one compound of the formula (III),

32. A liquid crystalline medium of claim 31 which comprises

15-40% by weight of at least one compound of formula I,

20-35% by weight of at least one compound of formula II,

35-50% by weight of at least one compound of formula III and

20-25% by weight of at least one compound of formula IV.

33. Liquid-crystalline medium according to claim 32, characterized in that it comprises:

at least one compound selected from each of formulae Ia and Ib ##STR56## at least one compound selected from the formulae II1, II2, II3 and II4, ##STR57## at least one compound selected from the formulae IIIa, IIIb and IIIc, ##STR58## and optionally at least one compound selected from the formulae IVa and IVb, ##STR59## in which ##STR60## and R¹, R², R³, R⁴, R⁵, L¹, L², L³, L⁴, L⁵ and L⁶ are each as defined above.