Highly collimating tapered light guide for uniform illumination of flat panel displays

• US 6,648,485 B1
• Filed: 11/13/2000
• Issued: 11/18/2003
• Est. Priority Date: 11/13/2000
• Status: Expired due to Term

• Current Assignee: AU Optronics Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Doany, Fuad E., Nishikai, Akiko, Suzuki, Masaru, Taira, Yoichi, Colgan, Evan G., Singh, Rama N.
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): WARD, JOHN A
• Application Number:
  US09/711,041
• Time in Patent Office: 1,100 Days
• Field of Search: 362/26, 362/31, 362/331, 362/551, 362/561
• US Class Current: 362/600
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide

Abstract

A light guide system has a light guide having a first end portion opposite a second end portion. The light guide provides a first surface and a second surface between the first and second end portions, and the second surface is inclined relative to the first surface. A light source is disposed along the first end portion on a first axis. A light redistribution device is disposed on an entrance of the light guide for receiving light from the light source and redistributing a portion of the light perpendicular to the first axis to provide a uniform light distribution from the first surface.

Claims

1. A light guide system for providing back-light illumination, comprising:

a light guide having a first end portion opposite a second end portion, the light guide including a first surface and a second surface between the first and second end portions, the second surface being inclined relative to the first surface;

a mirror disposed parallel to the second surface;

a light source disposed along the first end portion on a first axis; and

a light redistribution device disposed at an entrance of the light guide for receiving light from the light source and redistributing a portion of the light perpendicular to the first axis to provide a uniform light distribution from the first surface.

2. The light guide system, as recited in claim 1, wherein the first surface and the second surface are smooth.

3. The light guide system, as recited in claim 1, wherein the second surface is inclined relative to the first surface to produce collimated light by total internal reflection along the light guide.

4. The light guide system, as recited in claim 1, wherein the light redistribution device includes a structured entrance surface for the light guide.

5. The light guide system, as recited in claim 4, wherein the structured entrance surface includes a plurality of ridges extending parallel to the first axis.

6. The light guide system, as recited in claim 5, wherein the plurality of ridges is integrally formed in the light guide.

7. The light guide system, as recited in claim 4, wherein the structured entrance surface includes at least one facet forming an angle other than a perpendicular angle with the first surface and extending parallel to the first axis.

8. The light guide system, as recited in claim 4, wherein the structured entrance surface includes at least one curved surface extending parallel to the first axis.

9. The light guide system, as recited in claim 1, further comprising a plurality of ridges extending perpendicular to the first axis.

10. The light guide system, as recited in claim 1, further comprising a plurality of ridges disposed on the first surface and extending perpendicular to the first axis.

11. The light guide system, as recited in claim 1, further comprising a black material separated by a gap from at least one of the first surface and the second surface of the light guide for absorbing a portion of the light from the light source.

12. A light guide system for providing back-light illumination, comprising:

a light guide having a first end portion opposite a second end portion, the light guide including a first surface and a second surface between the first and second end portions, the second surface being inclined relative to the first surface;

a light source disposed along the first end portion wherein the first end portion defines a first axis and the light source extends along the first axis; and

a structured entrance formed in the first end portion of the light guide, the structured entrance including a plurality of angled surfaces extending along the first axis for redirecting light received from the light source to provide a uniform light distribution from the first surface of the light guide.

13. The light guide system, as recited in claim 12, wherein the first surface and the second surface are uniformly smooth.

14. The light guide system, as recited in claim 12, wherein the second surface is inclined relative to the first surface to provide total internal reflection in the light guide.

15. The light guide system, as recited in claim 12, wherein the structured entrance includes a plurality of ridges extending parallel to the first axis.

16. The light guide system, as recited in claim 15, wherein the plurality of ridges include triangular shaped cross-sections.

17. The light guide system, as recited in claim 12, further comprising a plurality of ridges formed on the structured entrance and extending perpendicular to the first axis.

18. The light guide system, as recited in claim 12, further comprising a plurality of ridges disposed on the first surface and extending perpendicular to the first axis.

19. The light guide system, as recited in claim 12, further comprising a black material separated by a gap from at least one of the first surface and the second surface of the light guide for absorbing a portion of the light from the light source.

20. The light guide system, as recited in claim 12, further comprising a faceted reflector adapted to redirect light entering the light guide.

21. The light guide system, as recited in claim 12, wherein the structured entrance includes at least one facet forming an angle other than a perpendicular angle with the first surface and extending parallel to the first axis.

22. The light guide system, as recited in claim 12, wherein the structured entrance includes at least one curved surface extending parallel to the first axis.

23. A light guide system for liquid crystal displays, comprising:

a light guide having a first end portion opposite a second end portion, the light guide including a first surface and a second surface between the first and second end portions, the second surface being inclined relative to the first surface;

a light source disposed along the first end portion wherein the first end portion defines a first axis and the light source extends along the first axis;

a reflector surrounding a portion of the light source and extending along the first axis to reflect light from the light source into the light guide;

a mirror disposed parallel to the second surface;

a structured entrance formed in the first end portion of the light guide, the structured entrance including a plurality of angled surfaces extending along the first axis for redirecting light received from the light source to provide a uniform light distribution from the first surface of the light guide; and

a liquid crystal pixel array disposed in operative relationship with the first surface for receiving light directed from the first surface to render an image.

24. The light guide system, as recited in claim 23, wherein the first surface and the second surface are uniformly smooth.

25. The light guide system, as recited in claim 23, wherein the second surface is inclined relative to the first surface to provide total internal reflection within the light guide.

26. The light guide system, as recited in claim 23, wherein the structured entrance includes a plurality of ridges extending parallel to the first axis.

27. The light guide system, as recited in claim 26, wherein the plurality of ridges include triangular shaped cross-sections.

28. The light guide system, as recited in claim 23, further comprising a plurality of ridges extending perpendicular to the first axis.

29. The light guide system, as recited in claim 23, further comprising a plurality of ridges disposed on the first surface and extending perpendicular to the first axis.

30. The light guide system, as recited in claim 23, further comprising a black material separated by a gap from at least one of the first surface and the second surface of the light guide for absorbing a portion of the light from the light source.

31. The light guide system, as recited in claim 23, wherein the reflector is faceted to redirect light entering the light guide.

32. The light guide system, as recited in claim 23, wherein the liquid crystal display includes a collimate and post diffuse display.

33. The light guide system, as recited in claim 23, wherein the liquid crystal display includes a color filterless display.

34. The light guide system, as recited in claim 23, wherein the structured entrance includes at least one facet forming an angle other than a perpendicular angle with the first surface and extending parallel to the first axis.

35. The light guide system, as recited in claim 23, wherein the structured entrance includes at least one curved surface extending parallel to the first axis.