Multiple lightguide backlight

• US 20050135115A1
• Filed: 12/23/2003
• Published: 06/23/2005
• Est. Priority Date: 12/23/2003
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Lamb, David J., Watson, Philip E., O'Neill, Mark B., Epstein, Kenneth A., Gardiner, Mark E., Marushin, Patrick H., Kotchick, Keith M.
• Granted Patent: US 7,303,322 B2
• Time in Patent Office: Days
• US Class Current: 362/613
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0076 Stacked arrangements of multiple light guides of the same or different cross-sectional area

Abstract

The present disclosure is directed to backlighting systems, which include first and second lightguides, at least one light source optically connected to an edge of the first lightguide and at least one light source optically connected to an edge of the second lightguide for supplying light into their respective interiors. In the appropriate exemplary embodiments, the backlighting systems of the present disclosure include an extractor disposed at a surface of the second lightguide for diffuse extraction of light from the interior of the second lightguide. In such exemplary embodiments, at least a portion of the light supplied into the interior of the second lightguide and then diffusely extracted therefrom enters the interior of the first lightguide through a substantially optically clear surface. In some exemplary embodiments, the backlighting systems of the present disclosure include recycling enhancement structures, which may be attached to the first lightguide.

Claims

1. A backlighting system, comprising:

a first lightguide having an interior;

at least one light source optically connected to an edge of the first lightguide for supplying light into the interior thereof;

a second lightguide having an interior;

at least one light source optically connected to an edge of the second lightguide for supplying light into the interior thereof; and

an extractor disposed at a surface of the second lightguide for diffuse extraction of light from the interior of the second lightguide;

wherein at least a portion of the light supplied into the interior of the second lightguide and then diffusely extracted therefrom enters the interior of the first lightguide through a substantially optically clear surface.

2. The backlighting system as recited in claim 1, further comprising a first recycling enhancement structure disposed at a surface of the first lightguide.

3. The backlighting system as recited in claim 2, wherein the first recycling enhancement structure comprises a reflective polarizer.

4. The backlighting system as recited in claim 3, wherein the first recycling enhancement structure further comprises a diffuser.

5. The backlighting system as recited in claim 4, wherein the diffuser is spatially graded.

6. The backlighting system as recited in claim 3, wherein the first recycling enhancement structure further comprises a prismatic structure.

7. The backlighting system as recited in claim 2, 3, 4, 5 or 6, wherein the first recycling enhancement structure is attached to a surface of the first lightguide.

8. The backlighting system as recited in claim 1, further comprising a second recycling enhancement structure disposed between the first lightguide and the second lightguide.

9. The backlighting system as recited in claim 8, wherein the second recycling enhancement structure comprises a prismatic structure.

10. The backlighting system as recited in claim 8 or 9, wherein the second recycling enhancement structure is attached to a surface of the first lightguide.

22. The backlighting system as recited in claim 1 or 11, wherein the first and second lightguides each comprise two opposing edges, at least one light source is optically connected to each of said edges, and the opposing edges of the first lightguide are not aligned with the opposing edges of the second lightguide.

23. The backlighting system as recited in claim 1 or 11, wherein the first and second lightguides each comprise two adjacent edges, at least one light source is optically connected to each of said edges, and the adjacent edges of the first lightguide are not aligned with the adjacent edges of the second lightguide.

37. The backlighting system as recited in claim 1, 11 or 24, wherein at least one of the first and the second lightguides has variable thickness.

38. The backlighting system as recited in claim 1, 11 or 24, wherein at least one of the first and second lightguides comprises a first wedge portion and a second wedge portion.

39. The backlighting system as recited in claim 1 or 24, wherein the extractor is spatially graded.

40. The backlighting system as recited in claim 1, 11 or 24, further comprising substantially optically clear surface extraction structures disposed on a surface of the first lightguide that faces the second lightguide.

41. The backlighting system as recited in claim 1, 11 or 24, further comprising a reflector sheet disposed next to a surface of the second lightguide that faces away from the first lightguide.

42. The backlighting system as recited in claim 1, 11 or 24, further comprising a diffuser sheet disposed next to a surface of the second lightguide that faces the first lightguide.

11. A backlighting system, comprising:

a first lightguide having an interior;

at least one light source optically connected to an edge of the first lightguide for supplying light into the interior thereof;

a second lightguide having an interior;

at least one light source optically connected to an edge of the second lightguide for supplying light into the interior thereof; and

a recycling enhancement structure disposed between the first lightguide and the second lightguide.

12. The backlighting system as recited in claim 11, wherein the recycling enhancement structure comprises a prismatic structure.

13. The backlighting system as recited in claim 12, wherein the prismatic structure comprises a surface defining a plurality of prisms having apexes pointing generally away from the second lightguide.

14. The backlighting system as recited in claim 11, wherein the recycling enhancement structure comprises a first surface defining a plurality of prisms substantially symmetric about a first horizontal axis and having apexes pointing generally away from the second lightguide and a second surface defining a plurality of prisms substantially symmetric about a second horizontal axis and having apexes pointing generally away from the second lightguide.

15. The backlighting system as recited in claim 14, wherein the first axis is generally orthogonal to the second axis.

16. The backlighting system as recited in claim 11, 12, 13, 14 or 15, wherein the recycling enhancement structure is attached to a surface of the first lightguide.

17. The backlighting system as recited in claim 11, further comprising an additional recycling enhancement structure disposed at a surface of the first lightguide.

18. The backlighting system as recited in claim 17, wherein the additional recycling enhancement structure comprises a reflective polarizer.

19. The backlighting system as recited in claim 18, wherein the additional recycling enhancement structure further comprises a diffuser.

20. The backlighting system as recited in claim 17, wherein the additional recycling enhancement structure further comprises a prismatic structure.

21. The backlighting system as recited in claim 17, 18, 19 or 20, wherein the additional recycling enhancement structure is attached to a surface of the first lightguide.

24. A backlighting system, comprising:

a first lightguide having an interior;

a plurality of light sources optically connected to a first edge of the first lightguide and a plurality of light sources optically connected to a second edge of the first lightguide for supplying light into the interior thereof;

a second lightguide having an interior;

a plurality of light sources optically connected to a first edge of the second lightguide and a plurality of light sources optically connected to a second edge of the second lightguide for supplying light into the interior thereof; and

an extractor disposed at a surface of the second lightguide for diffuse extraction of light from the interior thereof;

wherein at least a portion of the light supplied into the interior of the second lightguide and then diffusely extracted therefrom enters the interior of the first lightguide through a substantially optically clear surface.

25. The backlighting system as recited in claim 24, further comprising a first recycling enhancement structure disposed at a surface of the first lightguide.

26. The backlighting system as recited in claim 25, wherein the first recycling enhancement structure comprises a reflective polarizer.

27. The backlighting system as recited in claim 26, wherein the first recycling enhancement structure further comprises a diffuser.

28. The backlighting system as recited in claim 27, wherein the diffuser is spatially graded.

29. The backlighting system as recited in claim 28, wherein the first recycling enhancement structure further comprises a prismatic structure.

30. The backlighting system as recited in claim 25, 26, 27, 28 or 29, wherein the first recycling enhancement structure is attached to a surface of the first lightguide.

31. The backlighting system as recited in claim 24, further comprising a second recycling enhancement structure disposed between the first lightguide and the second lightguide.

32. The backlighting system as recited in claim 31, wherein the second recycling enhancement structure comprises a prismatic structure.

33. The backlighting system as recited in claim 32, wherein the prismatic structure comprises a surface defining a plurality of prisms having apexes pointing generally away from the second lightguide.

34. The backlighting system as recited in claim 31, wherein the second recycling enhancement structure comprises a first surface defining a plurality of prisms substantially symmetric about a first horizontal axis and having apexes pointing generally away from the second lightguide and a second surface defining a plurality of prisms substantially symmetric about a second horizontal axis and having apexes pointing generally away from the second lightguide.

35. The backlighting system as recited in claim 34, wherein the first axis is generally orthogonal to the second axis.

36. The backlighting system as recited in claim 31, 32, 33, 34 or 35, wherein the second recycling enhancement structure is attached to a surface of the first lightguide.