Liquid-crystal display device, compensator layer and method of manufacturing retardation foil

• US 20040257508A1
• Filed: 07/20/2004
• Published: 12/23/2004
• Est. Priority Date: 05/17/1996
• Status: Active Grant

• Current Assignee: Dirk J. Broer, Johannes A. M.M. Van Haaren, Peter Van De Witte, Rifat A.M. Hikmet
• Original Assignee: Dirk J. Broer, Johannes A. M.M. Van Haaren, Peter Van De Witte, Rifat A.M. Hikmet
• Inventors: Van Haaren, Johannes A. M.M., Van De Witte, Peter, Broer, Dirk J., Hikmet, Rifat A.M.
• Granted Patent: US 7,030,950 B2
• Time in Patent Office: Days
• US Class Current: 349/134
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/133632 with refractive index ellipsoid inclined relative to the LC-layer surface
• CPC Class Codes: G02F 1/1396 the liquid crystal being selectively controlled between a twisted state and a non-twisted state, e.g. TN-LC cell G02F1/141 takes precedence
• CPC Class Codes: G02F 2413/105 with varying inclination in thickness direction, e.g. hybrid oriented discotic LC

Abstract

A method of forming a liquid-crystal display device having a display cell comprises forming retardation foils on substrates using polymerized or vitrified liquid-crystal material wherein the liquid-crystal molecules of the polymerized or vitrified liquid-crystal material have a tilt angle with respect to a plane parallel to the substrates and so that the retardation foils have substantially complementary indicatrices and so that each one of the retardation foils brings about the compensation of approximately half the display cell in the driven state.

Claims

1. A method of manufacturing a retardation foil, characterized in that a liquid-crystalline mixture in the smectic C-phase between two homeotropically aligning substrates is cured by means of polymerization.

2. A method of manufacturing a liquid-crystal display device having a display cell comprising:

forming a layer of a nematic, liquid-crystal material so as to have a twist angle which lies in a range of 60-120 degrees, between two substantially parallel substrates;

forming first and second polarizers so as to have first and second polarizing directions and arranging the first and second polarizers on at least one of the substrates; and

forming first and second retardation foils in a predetermined relationship with the first and second polarizers, and so that the first and second retardation foils respectively comprise polymerized or vitrified liquid-crystalline material comprising liquid-crystal molecules which are respectively arranged to;

a) have average orientations which respectively extend in first and second directions which directions are respectively parallel to first and second planes that are normal to the substrates, the first and second planes being oriented with respect to one another at an angle in a range of 60 to 120 degrees; and

b) exhibit first and second average tilt angles relative to the substrates.

3. A method as set forth in claim 2, comprising:

forming the first and second retardation foils so that a twist angle of the liquid crystal material lies in one of the ranges of 60-<

90 and >

90-120 and so that the angle with which the first and second planes are oriented with respect to one another is essentially the same as the twist angle of the liquid crystal material.

4. A method as set forth in claim 2, comprising:

forming the retardation foils so that an average tilt angle of the first retardation foil is 40 degrees.

5. A method as set forth in claim 2, comprising:

forming the retardations foils so that an average tilt angle of the second retardation foil is 40 degrees.

6. A method as set forth in claim 2, comprising:

forming the first and second polarizers so that the first and second polarizing directions are oriented at right angles to each other.

7. A method as set forth in claim 2, comprising:

forming the first and second polarizers so that the first and second polarizing directions are non-parallel with the first and second planes.

8. A method as set forth in claim 2, comprising:

orienting the liquid-crystal molecules in the polymerized or vitrified liquid-crystalline material so as to be substantially constant in at least one of the retardation foils.

9. A method as set forth in claim 2, comprising:

varying the tilt angle of the liquid-crystal molecules in the polymerized or vitrified liquid-crystalline material, in at least one of the retardation foils, in a direction at right angles to the foil.

10. A method as set forth in claim 9, comprising:

forming the retardation foils so that the average tilt angle of the liquid-crystal molecules in the polymerized or vitrified liquid-crystalline material is at least 10 degrees.

11. A method as set forth in claim 2, comprising:

forming the retardation foils so that the tilt angle of the liquid-crystal molecules in the polymerized or vitrified liquid-crystalline material is substantially constant in at least one of the retardation foils.

12. A method as set forth in claim 2, comprising:

forming the retardation foils so that the tilt angle of the liquid-crystal molecules in the polymerized or vitrified liquid-crystalline material is at least 10 degrees and at most 70 degrees.

13. A method as set forth in claim 2, comprising:

forming the retardation foils so that the polymerized or vitrified material comprises liquid-crystalline molecules which have, at one end, a non-polar group and, at the other end, a polar group.

14. A method as set forth in claim 13, wherein, at the end having the non-polar group, the liquid-crystalline molecules are covalently bonded to the polymerized or vitrified material.

15. A method as set forth in claim 2, comprising:

forming the retardation foils so that the direction of orientation of the liquid-crystal molecules in the polymerized or vitrified liquid-crystalline material is substantially constant in at least one of the retardation foils.

16. A method as set forth in claim 2, comprising:

forming the retardation foils so that the tilt angle of the liquid-crystal molecules in the polymerized or vitrified liquid-crystalline material varies in at least one of the retardation foils.

17. A method as set forth in claim 2, comprising:

forming the liquid-crystal molecules in the polymerized or vitrified liquid-crystalline material so that the tilt angle is substantially constant in at least one of the retardation foils.

18. A method as set forth in claim 2, comprising:

forming the polymerized or vitrified material so that the liquid-crystalline molecules are provided, at one end, with a non-polar group and, at the other end, with a polar group.

19. A method as set forth in claim 2, comprising:

forming the liquid-crystalline molecules at the end provided with the non-polar group so that the liquid-crystalline molecules are covalently bonded to the polymerized or vitrified material.

20. A method of manufacturing a compensator layer comprising:

forming first and second retardation foils by polymerizing or vitrifying liquid-crystalline material comprising liquid-crystal molecules in manner wherein the liquid-crystal molecules in the polymerized or vitrified liquid-crystalline material of the first and second retardation foils respectively exhibit first and second tilt angles which are respectively parallel to first and second planes that are normal to major surfaces of the foils and that are angled with respect to one another by an angle of 60-120 degrees.

21. A method as set forth in claim 20, wherein the forming of the first and second retardation foils is such that the angle between the first and second planes are that normal to the major surfaces of the foils lies in one of the ranges of 60-<

90 and >

90-120 degrees.

22. A method as set forth in claim 20, wherein the liquid-crystalline material comprises a reaction product of a monomers or of a mixture of monomers having a reactive group and which can be oriented prior to polymerization.

23. A method as set forth in claim 22, wherein the reactive group comprises one of a vinyl ether, a thiolene system, an epoxy group and a (meth)acrylate group.

24. A method as set forth in claim 22, wherein the monomers are polymerized using thermal polymerization or under the influence of actinic radiation.

25. A method as set forth in claim 24, wherein the actinic radiation comprises UV light.

26. A method as set forth in claim 24, further comprising the step of selecting the temperature at which the mixture is polymerized.

27. A method as set forth in claim 22, wherein the mixture comprises monomers having two or more reactive groups which during polymerization lead to the formation of a three-dimensional network.

28. A method as set forth in claim 20, comprising:

preparing liquid-crystal molecules which are provided, at one end, with a non-polar group and, at the other end, with a polar group;

applying the liquid-crystalline molecules to a substrate so that they assume a homeotropic phase proximate the substrate and so that a desired ordering of the tilt in the liquid-crystalline material of the retardation foil takes place almost spontaneously and obviates treatment with an electric field to induce the tilt.

29. A method of forming a liquid-crystal display device having a display cell comprising:

forming retardation foils on substrates using polymerized or vitrified liquid-crystal material wherein the liquid-crystal molecules of the polymerized or vitrified liquid-crystal material have a tilt angle with respect to a plane parallel to the substrates and so that the retardation foils have substantially complementary indicatrices and so that each one of the retardation foils brings about the compensation of approximately half the display cell in the driven state.