Compensators for liquid crystal displays and the use and manufacture of the compensators

• US 20030193636A1
• Filed: 04/16/2002
• Published: 10/16/2003
• Est. Priority Date: 04/16/2002
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company), Rolic AG, Rolle AG
• Original Assignee: 3M Innovative Properties Company (3M Company), Rolic AG
• Inventors: Seiberle, Hubert, Bachels, Thomas, Schadt, Martin, Allen, Richard C., Funfschilling, Jurg
• Granted Patent: US 6,919,946 B2
• Time in Patent Office: Days
• US Class Current: 349/117
• 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 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133632 with refractive index ellipsoid inclined relative to the LC-layer surface
• CPC Class Codes: G02F 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
• CPC Class Codes: G02F 2413/04 Number of plates greater than or equal to 4
• CPC Class Codes: G02F 2413/10 with refractive index ellipsoid inclined, or tilted, relative to the LC-layer surface O plate

Abstract

Compensation of a liquid crystal display can be achieved using a compensation structure, having, in the following order: a) a first o-plate; b) a first retarder; c) a liquid crystal cell; d) a second retarder; and e) a second o-plate. The first and second retarders can be c-plates or biaxial retarders.

Claims

1. A liquid crystal display, comprising:

a first o-plate having a first azimuthal orientation;

a first c-plate;

a liquid crystal cell comprising a rear surface and a front surface, wherein the liquid crystals at the rear surface have a second azimuthal orientation and the liquid crystals at the front surface have a third azimuthal orientation and wherein the first c-plate is disposed between the first o-plate and the liquid crystal cell;

a second c-plate; and

a second o-plate having a fourth azimuthal orientation, wherein the second c-plate is disposed between the second o-plate and the liquid crystal cell;

wherein the first, second, third and fourth azimuthal orientations are disposed in a helical arrangement.

2. The liquid crystal display of claim 1, wherein

the second azimuthal orientation differs from the first azimuthal orientation by an angle in the range of 75 to 105 degrees in a first rotational direction,

the third azimuthal orientation differs from the second azimuthal orientation by an angle in the range of 75 to 105 degrees in the first rotational direction, and

the fourth azimuthal orientation differs from the third azimuthal orientation by an angle in the range of 75 to 105 degrees in the first rotational direction.

3. The liquid crystal display of claim 2, wherein the first rotational direction is clockwise as viewed looking from the first o-plate toward the layer of liquid crystals.

4. The liquid crystal display of claim 2, wherein the first rotational direction is counter-clockwise as viewed looking from the first o-plate toward the layer of liquid crystals.

5. The liquid crystal display of claim 1, wherein the first and second o-plates are positive o-plates.

6. The liquid crystal display of claim 1, wherein the first and second c-plates are negative c-plates.

7. The liquid crystal display of claim 1, wherein the liquid crystal cell is a twisted nematic liquid crystal cell.

8. The liquid crystal display of claim 1, further comprising

a rear polarizer positioned with the first c-plate and first o-plate between the rear polarizer and the liquid crystal cell;

and

a front polarizer positioned with the second c-plate and second o-plate between the front polarizer and the liquid crystal cell.

9. The liquid crystal display of claim 8, wherein the rear polarizer, front polarizer, and liquid crystal cell are disposed in an e-mode configuration.

10. The liquid crystal display of claim 8, wherein the rear polarizer, front polarizer, and liquid crystal cell are disposed in an o-mode configuration.

11. The liquid crystal display of claim 1, wherein the optical axis of the first o-plate is tilted at a substantially uniform value.

12. The liquid crystal display of claim 1, wherein the optical axis of the first o-plate varies in tilt angle from the front to the back of the first o-plate.

13. The liquid crystal display of claim 12, wherein the tilt angle of the first o-plate increases from the front to the back of the first o-plate.

14. The liquid crystal display of claim 12, wherein the optical axis of the second o-plate varies in tilt angle from the front to the back of the second o-plate.

15. The liquid crystal display of claim 14, wherein the tilt angle of the first o-plate increases from the front to the back of the first o-plate the tilt angle of the second o-plate decreases from the front to the back of the second o-plate.

16. The liquid crystal display of claim 1, further comprising a third c-plate positioned so that the first o-plate is between the third c-plate and the liquid crystal cell.

17. The liquid crystal display of claim 16, further comprising a fourth c-plate positioned so that the second o-plate is between the fourth c-plate and the liquid crystal cell.

18. A liquid crystal display, comprising:

a first o-plate;

a first retarder;

a liquid crystal cell, wherein the first retarder is disposed between the first o-plate and the liquid crystal cell;

a second retarder, wherein at least one of the first and second retarders is a biaxial retarder; and

a second o-plate, wherein the second retarder is disposed between the second o-plate and the liquid crystal cell.

19. The liquid crystal display of claim 18, wherein both the first and second retarders are biaxial retarders.

20. The liquid crystal display of claim 18, wherein one of the first and second retarders is a c-plate.

21. The liquid crystal display of claim 18, wherein the biaxial retarder has a negative out-of-plane birefringence.

22. The liquid crystal display of claim 18, wherein the first and second o-plates are positive o-plates.

23. The liquid crystal display of claim 18, further comprising a first c-plate positioned so that the first o-plate is between the first c-plate and the liquid crystal cell.

24. The liquid crystal display of claim 23, further comprising a second c-plate positioned so that the second o-plate is between the second c-plate and the liquid crystal cell.

25. A method of compensation for a liquid crystal display, the method comprising:

directing light through a liquid crystal cell and compensation structure comprising

a first o-plate having a first azimuthal orientation;

a first c-plate;

a liquid crystal cell comprising a rear surface and a front surface, wherein the liquid crystals at the rear surface have a second azimuthal orientation and the liquid crystals at the front surface have a third azimuthal orientation and wherein the first c-plate is disposed between the first o-plate and the liquid crystal cell;

a second c-plate; and

a second o-plate having a fourth azimuthal orientation, wherein the second c-plate is disposed between the second o-plate and the liquid crystal cell;

wherein the first, second, third and fourth azimuthal orientations are disposed in a helical arrangement.

26. A method of compensation for a liquid crystal display, the method comprising:

directing light through a liquid crystal cell and compensation structure comprising

a first o-plate;

a first retarder;

a liquid crystal cell, wherein the first retarder is disposed between the first o-plate and the liquid crystal cell;

a second retarder, wherein at least one of the first and second retarders is a biaxial retarder; and

a second o-plate, wherein the second retarder is disposed between the second o-plate and the liquid crystal cell.