Front Light Devices and Methods of Fabrication Thereof

• US 20090296193A1
• Filed: 05/28/2009
• Published: 12/03/2009
• Est. Priority Date: 05/28/2008
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: MIENKO, Marek, GRUHLKE, Russell W., NARAYANAN, Kollengode S., WANG, Lai, XU, Gang, BITA, Ion
• Granted Patent: US 8,346,048 B2
• Time in Patent Office: Days
• US Class Current: 359/291
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A illumination device comprises a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide. A turning microstructure is disposed on a first side of the light guide configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure comprises a plurality of indentations. A cover is physically coupled to the light guide and disposed over the turning microstructure. An interlayer is between the cover and the light guide, wherein the interlayer physically couples the cover to the light guide. A plurality of open regions is between the interlayer and the plurality of indentations. Various embodiments include methods of coupling the cover to the light guide while preserving open regions between the cover and plurality of indentations.

Claims

1. An illumination device comprising:

a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide;

a turning microstructure disposed on a first side of the light guide configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure comprises a plurality of indentations;

a cover physically coupled to the light guide and disposed over the turning microstructure;

an interlayer between the cover and the light guide, wherein the interlayer physically couples the cover to the light guide; and

a plurality of open regions between the interlayer and the plurality of indentations;

wherein the light guide has a first index of refraction and the interlayer has a second index of refraction and the second index of refraction is lower than the first index of refraction.

2. The illumination device of claim 1, wherein the plurality of indentations comprises a plurality of V-shaped grooves and the open regions comprise substantially triangular cross-sections.

3. The illumination device of claim 1, wherein the plurality of indentations comprises a plurality of grooves and the open regions comprise substantially trapezoidal cross-sections.

4. The illumination device of claim 1, wherein the turning microstructure comprises a diffraction grating.

5. The illumination device of claim 1, wherein the cover comprises a thickness in the range of about 10 microns to about 300 microns.

6. The illumination device of claim 1, wherein the interlayer contacts about 90% or more surface area of the first side of the light guide.

7. The illumination device of claim 1, wherein the plurality of open regions is preserved between the interlayer and the turning microstructure.

8. The illumination device of claim 1, wherein the light guide comprises a substrate, and wherein the turning microstructure is formed directly on the substrate.

9. The illumination device of claim 1, wherein the light guide comprises a substrate and a turning film, and wherein the turning microstructure is formed on the turning film.

10. The illumination device of claim 1, wherein the interlayer comprises a thickness less than the height of an indentation in the turning microstructure.

11. The illumination device of claim 1, wherein the interlayer comprises a cured polymer material having a glass transition point of less than about 200°

C.

12. The illumination device of claim 1, wherein the interlayer comprises a cured polymer material having a glass transition point of less than about 0°

C.

13. The illumination device of claim 1, wherein the interlayer comprises a surface energy of less than about 35 dynes/cm.

14. The illumination device of claim 1, wherein the interlayer comprises an elastomeric material.

15. The illumination device of claim 14, wherein the interlayer comprises a siloxane backbone.

16. The illumination device of claim 14, wherein the interlayer comprises cross-linking agents.

17. The illumination device of claim 1, wherein the cover further comprises an anti-glare film, an anti-static film, an anti-smudge film, a color filter, or a touch panel.

18. The illumination device of claim 1, further comprising an optical layer having a low refractive index between the second side of the light guide and the plurality of display elements.

19. The illumination device of claim 1, wherein the open regions are filled with air.

20. A illumination device comprising:

a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide;

a turning microstructure disposed on a first side of the light guide configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure comprises a plurality of indentations;

a cover physically coupled to the light guide and disposed over the turning microstructure;

an interlayer between the cover and the light guide, wherein the interlayer physically couples the cover to the light guide; and

a plurality of regions between the interlayer and the plurality of indentations at least partially comprising a material different from the interlayer.

21. The illumination device of claim 20, wherein the light guide has a first index of refraction and the interlayer has a second index of refraction and the second index of refraction is lower than the first index of refraction.

22. The illumination device of claim 20, wherein the plurality of regions comprises a reflective material that lines a surface of the plurality of indentations.

23. The illumination device of claim 22, wherein the reflective material comprises a thickness of at least 50 nm.

24. The illumination device of claim 22, wherein the reflective material comprises a thickness of at least 100 nm.

25. The illumination device of claim 20, wherein the interlayer contacts the reflective material within the plurality of indentations.

26. The illumination device of claim 20, wherein the reflective material fills the plurality of regions.

27. The illumination device of claim 20, wherein the plurality of regions comprises a material having an index of refraction substantially close to air.

28. The illumination device of claim 27, wherein the plurality of regions comprises a substantially porous material.

29. The illumination device of claim 20, wherein the interlayer does not extend over the plurality of regions, and the material of the regions contacts the cover.

30. The illumination device of claim 20, further comprising a plurality of barriers separating the plurality of regions from the interlayer.

31. An illumination device comprising:

a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide;

a turning microstructure disposed on a first side of the light guide configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure comprises a plurality of indentations;

a cover physically coupled to the light guide and disposed over the turning microstructure;

a plurality of open regions between the cover and the plurality of indentations;

wherein the light guide has a first index of refraction and the cover has a second index of refraction and the second index of refraction is lower than the first index of refraction.

32. The illumination device of claim 31, wherein the plurality of indentations comprises a plurality of V-shaped grooves and the open regions comprise substantially triangular cross-sections.

33. The illumination device of claim 31, wherein the plurality of indentations comprises a plurality of grooves and the open regions comprise substantially trapezoidal cross-sections.

34. The illumination device of claim 31, wherein the turning microstructure comprises a diffraction grating.

35. The illumination device of claim 31, wherein the cover directly contacts about 90% or more surface area of the first side of the light guide.

36. A method of manufacturing a illumination device comprising:

providing a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide, said light guide having turning microstructure disposed on a first side thereof that is configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure comprises a plurality of indentations;

providing a cover disposed over the turning microstructure; and

physically coupling the cover to the light guide by an interlayer such that a plurality of open regions are between the interlayer and the plurality of indentations,

wherein the light guide has a first index of refraction and the interlayer has a second index of refraction and the second index of refraction is lower than the first index of refraction.

37. The method of claim 36, wherein the interlayer comprises a surface energy of less than about 35 dynes/cm.

38. The method of claim 36, wherein the interlayer comprises an elastomeric material.

39. The method of claim 36, wherein the interlayer comprises a thickness of about 1/10 of the height of an indentation in the turning microstructure.

40. The method of claim 36, wherein the interlayer comprises a polymer material with a glass transition point of less than about 200°

C.

41. The method of claim 36, wherein the interlayer comprises a polymer material with a glass transition point of less than about 0°

C.

42. The method of claim 36, wherein forming the plurality of indentations comprises forming a plurality of triangular grooves.

43. The method of claim 36, wherein forming the plurality of indentations comprises forming a plurality of trapezoidal grooves.

44. The method of claim 36, wherein forming the plurality of indentations comprises forming a diffraction grating.

45. A method of manufacturing a illumination device comprising:

providing a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide, said light guide having turning microstructure disposed on a first side thereof that is configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure comprises a plurality of indentations;

providing a cover disposed over the turning microstructure; and

physically coupling the cover to the light guide by an interlayer such that a plurality of regions between the interlayer and the plurality of indentations at least partially comprises a material different from the interlayer.

46. The method of claim 45, wherein said turning microstructure is formed by a method comprising:

forming a dissolvable layer over the first side of the light guide;

forming the plurality of indentations through the dissolvable layer and the light guide;

depositing a material over the light guide so that the material at least partially fills the plurality of indentations; and

removing the dissolvable layer.

47. The method of claim 46, wherein the dissolvable layer comprises photoresist.

48. The method of claim 45, wherein the light guide has a first index of refraction and the interlayer has a second index of refraction and the second index of refraction is lower than the first index of refraction.

49. The method of claim 45, wherein the material comprises a metallic material.

50. The method of claim 45, further comprising filling the regions with a fluoroplastic material.

51. The method of claim 45, further comprising filling the regions with an aerogel precursor material.

52. The method of claim 45, further comprising filling the regions with a sol-gel material.

53. A method of manufacturing a illumination device comprising:

providing a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide, said light guide having turning microstructure disposed on a first side thereof that is configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure comprises a plurality of indentations;

physically coupling a cover to the light guide, wherein the cover is disposed over the turning microstructure; and

wherein the light guide has a first index of refraction and the cover has a second index of refraction and the second index of refraction is lower than the first index of refraction.

54. The method of claim 53, wherein the turning microstructure is formed on a light guide that comprises a cross-linked polymer, the cover comprises a polymeric material, and providing a cover physically coupled to the light guide comprises diffusing portions of the cover to the light guide in areas between indentations.

55. The method of claim 53, wherein physically coupling a cover to the light guide comprises:

coating a surface of the cover facing the light guide with a solvent, wherein the cover and the light guide are soluble in the solvent; and

placing the cover with the solvent over the light guide.

56. The method of claim 53, further comprising applying pressure and heat to the cover to obtain inter-diffusion between the cover and the light guide in areas between the plurality of indentations.

57. The method of claim 53, wherein providing a cover physically coupled to the light guide comprises oxidizing a surface of the cover facing the light guide.

58. An illumination device comprising:

a means for guiding light having a first end for receiving light and configured to support propagation of light along the length of the light guiding means;

a means for turning light disposed on a first side of the light guiding means configured to turn light incident on the first side and to direct the light out a second opposite side of the light guiding means, wherein the turning means comprises a plurality of means for reflecting light;

a means for covering physically coupled to the light guiding means and disposed over the turning means;

a means for physically coupling between the covering means and the light guiding means, wherein the coupling means physically couples the covering means to the light guiding means; and

a plurality of open regions between the coupling means and the plurality of reflecting means;

wherein the light guiding means has a first index of refraction and the coupling means has a second index of refraction and the second index of refraction is lower than the first index of refraction.

59. The illumination device of claim 58, wherein the light guiding means comprises a light guide, or the turning means comprises a turning microstructure, or the covering means comprises a cover, or the coupling means comprises an interlayer, or the reflecting means comprises indentations.

60. A illumination device comprising:

a means for guiding light having a first end for receiving light and configured to support propagation of light along the length of the light guiding means;

a means for turning light disposed on a first side of the light guide configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning means comprises a plurality of means for reflecting light;

a means for covering physically coupled to the light guide and disposed over the turning means;

a means for physically coupling between the covering means and the light guiding means, wherein the coupling means physically couples the covering means to the light guiding means; and

a plurality of regions between the coupling means and the plurality of reflecting means at least partially comprising a material different from the coupling means.

61. The illumination device of claim 60, wherein the light guiding means comprises a light guide, or the turning means comprises a turning microstructure, or the covering means comprises a cover, or the coupling means comprises an interlayer, or the reflecting means comprises indentations.

62. An illumination device comprising:

a means for guiding light having a first end for receiving light and configured to support propagation of light along the length of the light guiding means;

a means for turning light disposed on a first side of the light guiding means configured to turn light incident on the first side and to direct the light out a second opposite side of the light guiding means, wherein the turning means comprises a plurality of means for reflecting light;

a means for covering physically coupled to the light guide and disposed over the turning means;

a plurality of open regions between the covering means and the plurality of reflecting means; and

wherein the light guiding means has a first index of refraction and the covering means has a second index of refraction and the second index of refraction is lower than the first index of refraction.

63. The illumination device of claim 62, wherein the light guiding means comprises a light guide, or the turning means comprises a turning microstructure, or the covering means comprises a cover, or the reflecting means comprises indentations.