Claims
- 1. In a liquid crystal phase having ferroelectric properties useful for rapidly switching displays and comprising at least two liquid crystalline compounds which form an achiral base mixture having a tilted smectic phase, and a chiral doping substance, the improvement wherein said chiral doping substance contains one or more compounds of the formula
- R.sup.1 -(A.sup.0 -Z.sup.0).sub.p -A-R.sup.2
- wherein one of the radicals
- R.sup.1 and R.sup.2 is an alkyl group or a polyfluoroalkyl group containing 1 to 15 C atoms in each case, wherein one or more CH.sub.2 groups or CF.sub.2 groups may also be replaced by a group selected from the group comprising --O--, --CHCN--, --O--CO--, --CO-- O-- and --CH.dbd.CH.dbd. or else by a combination of two suitable said groups, two hetero atoms not being directly linked to each other;
- and the other radical has the formula ##STR35## wherein X is --CO--O--, --O--CO--, --O--, --CH.dbd.CH.dbd., or a single bond,
- O is alkylene containing 1 to 5 C atoms, wherein a CH.sub.2 group not linked to X may also be replaced by --O--, --CO--, --O--CO--, --CO--O--, or --CH.dbd.CH--, or a single bond,
- Y is CN, halogen, methyl, or methoxy,
- R is an alkyl group differing from Y and containing 1 to 18 C atoms wherein one or two non-adjacent CH.sub.2 groups may also be replaced by --O--, --O--CO--, --CO--O--, and/or --CH.dbd.CH--,
- A.sup.0 is unsubstituted 1,4-phenylene or 1,4-phenylene substituted singly or multiply by halogen atoms wherein one or more CH groups may also be replaced by N;
- Z.sup.0 is --CO--O--, --O--CO--, --CH.sub.2 O--, --OCH.sub.2 --, --CH.sub.2 CH.sub.2 --, or a single bond;
- P is 2 or 3; and
- A is ##STR36## or trans-1,4-cyclohexylene; with the proviso that, when A is trans-1,4-cyclohexylene, Y is CN.
- 2. A liquid crystal phase according to claim 1, wherein R.sup.1 is straight-chain alkoxy, alkanoyloxy, alkoxycarbonyl or alkoxycarbonyloxy each having 5 to 12 C atoms.
- 3. A liquid crystal phase according to claim 1, wherein A ##STR37##
- 4. A liquid crystal phase according to claim 3, wherein R.sup.2 is straight-chain alkyl or 5 to 12 C atoms.
- 5. A liquid crystal phase according to claim 3, wherein p is 2.
- 6. A liquid crystal phase according to claim 1, wherein (A.sup.0 -Z.sup.0).sub.p is selected from the following formulae ##STR38## where the formula ##STR39## represents 2- and 2'-fluorobiphenylene substitution.
- 7. A liquid crystal phase according to claim 1, wherein (A.sup.0 -Z.sup.0).sub.p is selected from the following formulae ##STR40## and Z.sup.0 is not a single bond.
- 8. A liquid crystal phase according to claim 1, wherein one of the radicals R.sup.1 and R.sup.2 has the formula ##STR41## wherein X is --CO--O--, --O--CO-- or a single bond;
- Q is --CH.sub.2 --, --CH.sub.2 CH.sub.2 -- or a single bond; and
- R is an alkyl group containing 1 to 18 C atoms.
- 9. In a liquid crystal phase having ferroelectric properties useful for rapidly switching displays and comprising at least two liquid crystalline compounds which form an achiral base mixture having a tilted smectic phase, and a chiral doping substance, the improvement wherein said chiral doping substance contains one or more compounds of the formula ##STR42## wherein one of the radicals R.sup.1 and R.sup.2 is an alkyl group or a polyfluoroalkyl group containing 1 to 15 C atoms in each case, wherein one or more CH.sub.2 groups of CF.sub.2 groups may also be replaced by a group selected from the group comprising --O--, --CHCN--, --O--CO--, --CO--O-- and --CH.dbd.CH-- or else by a combination of two suitable said groups, two hetero atoms not being directly linked to each other;
- and the other radical has the formula ##STR43## wherein X is --CO--O--, --O--CO--, --O--, --CH.dbd.CH, or a single bond,
- Q is alkylene containing 1 to 5 C atoms, wherein a CH.sub.2 group not linked to X may also be replaced by --O--, 'CO--, --O--CO--, --CO--O--, or --CH.dbd.CH--, or a single bond,
- Y is CN, halogen, methyl, or methoxy;
- R is an alkyl group differing from Y and containing 1 to 18 C atoms wherein one or two non-adjacent CH.sub.2 groups may also be replaced by --O--, --O--CO--, --CO--O--, and/or --CH.dbd.CH--,
- A.sup.0 is unsubstituted 1,4-phenylene or 1,4-phenylene substituted singly or multiply by halogen atoms wherein one or more CH groups may also be replaced by N;
- Z.sup.0 is --CO--O--, --O--CO--, --CH.sub.2 O--, --OCH.sub.2 --, --CH.sub.2 CH.sub.2 -- or a single bond;
- P is 2 or 3.
- 10. In a ferroelectric electrooptical display element comprising a liquid crystal phase having ferroelectric properties, the improvement wherein said phase is one of claim 1.
- 11. A ferroelectric display element of claim 10 capable of operating by the surface stabilized ferroelectric liquid crystal mechanism.
- 12. A liquid crystal phase according to claim 1, wherein X is --CO--O--, --O--CO--, or a single bond; Q is --CH.sub.2 --, --CH.sub.2 CH.sub.2 --, or a single bond; Y is CH.sub.3, CN, or Cl; and R is straight-chain alkyl having 1-10 C atoms.
- 13. A liquid crystal phase according to claim 12, wherein R.sup.2 is straight-chain alkyl of 5-12 C atoms.
- 14. A liquid crystal phase according to claim 12, wherein p is 2.
Priority Claims (2)
Number |
Date |
Country |
Kind |
3533333 |
Sep 1985 |
DEX |
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3608500 |
Mar 1986 |
DEX |
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Parent Case Info
This is a division of application Ser. No. 07/051,120 filed May 13, 1987, now U.S. Pat. No. 4,886,620.
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Foreign Referenced Citations (1)
Number |
Date |
Country |
0136725 |
Oct 1988 |
EPX |
Non-Patent Literature Citations (1)
Entry |
Scheuble, "Liquid Crystal Displays with High Information Content," Kontakte (Darmstadt), 1989 (1), pp. 34-48. |
Divisions (1)
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Number |
Date |
Country |
Parent |
51120 |
May 1987 |
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