Reflective nanofiber lighting devices

• US 8,884,507 B2
• Filed: 11/17/2010
• Issued: 11/11/2014
• Est. Priority Date: 12/03/2009
• Status: Active Grant

• Current Assignee: Research Triangle Institute
• Original Assignee: Research Triangle Institute
• Inventors: Davis, James Lynn, Walls, Howard J., Mills, Karmann, Gupta, Vijay, Lamvik, Michael Kasper
• Primary Examiner(s): Hanley, Britt D
• Application Number:
  US13/513,433
• Publication Number:
  US 20120281428A1
• Time in Patent Office: 1,455 Days
• Field of Search: None
• US Class Current: 313/498
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/0041 provided in the bulk of the light guide

Abstract

A fiber-based reflective lighting device and a lighting device. The fiber-based reflective lighting device includes a source configured to generate a primary light, a mat of reflective fibers which diffusely reflects light upon illumination with at least the primary light, and a light exit configured to emanate the reflected light. The lighting device includes a housing, a source configured to generate primary light and direct the primary light into the housing, a reflective mat of fibers disposed inside the housing at a position to reflect the primary light, and a light exit in the housing configured to emanate the reflected light from the housing.

Claims

1. A fiber-based reflective lighting device comprising:

a source configured to generate a primary light;

a mat of reflective fibers;

said fibers layered upon each other in a random manner to form a structure which diffusively reflects at least 70% of incident visible light upon illumination with at least the primary light, and

a light exit configured to emanate the reflected light.

2. The device of claim 1, further comprising:

a luminescent sheet including light stimulatable particles configured to emit secondary light upon receiving the primary light.

3. The device of claim 2, wherein the light emanated from the light exit has a color rendering index greater than 70.

4. The device of claim 1, wherein the mat of reflective fibers reflects said incident visible light backward.

5. The device of claim 4, wherein the mat of reflective fibers comprises:

at least one of a planar or a curved reflector surface disposed behind or in front of the luminescent sheet.

6. The device of claim 4, wherein the reflector surface comprise spherical or cylindrical reflector surfaces.

7. The device of claim 1, wherein the reflective fibers comprise a dielectric material having an index of refraction greater than 1.6.

8. The device of claim 7, wherein the dielectric material comprises at least one of BaSO₄, ZnO, TiO₂, and Al₂O₃.

9. The device of claim 1, wherein the mat of reflective fibers comprises a reflective material having a reflectivity greater than 0.8.

10. The device of claim 9, wherein the reflective material comprises at least one of Al, Au, Ag, TiO₂, ZnO, BaSO₄, and Zn.

11. The device of claim 1, wherein the reflective fibers comprise flat-shaped nanofibers comprising a laterally extending surface for reflection of the light.

12. The device of claim 11, wherein the laterally extending surface comprises a surface with a lateral extension of 1 micron or larger.

13. The device of claim 11, wherein the laterally extending surface comprises a surface with a lateral extension of 10 microns or larger.

14. The device of claim 11, wherein the laterally extending surface comprises a surface with a lateral extension of 20 microns or larger.

15. The device of claim 11, wherein the laterally extending surface comprises a surface with a lateral extension of 50 microns or larger.

16. The device of claim 1, further comprising:

an optically clear encapsulant securing the mat of reflective fibers.

17. The device of claim 16, wherein the encapsulant has an index of refraction that differs from the material being encapsulated by at least 0.10.

18. The device of claim 1, wherein the mat of reflective fibers comprises:

at least one of a planar or a curved reflector surface.

19. The device of claim 1, wherein the source configured to generate said primary light comprises a light emitting diode.

20. The device of claim 3, where the luminescent sheet includes a diffuse reflector.

21. The device of claim 1, wherein the mat of reflective fibers comprises fibers having an average fiber diameter in a range between 50 to 2,000 nm.

22. The device of claim 21, wherein the fibers have an average fiber diameter is in a range between 100 nm to 800 nm.

23. The device of claim 21, wherein the fibers have a thickness in a range between 0.01 microns and 2,000 microns.

24. The device of claim 1, wherein the mat of reflective fibers has a thickness in a range between 1 to 500 microns.

25. The device of claim 1, further comprising:

stimulatable particles disposed at least on a surface of the mat of reflective fibers or a surface of nanofibers separate from the mat of reflective fibers and comprising luminescent particles.

26. The device of claim 25, wherein the luminescent particles comprise at least one of quantum dots and phosphors.

27. The device of claim 26, wherein the quantum dots comprise at least one of silicon, germanium, indium phosphide, indium gallium phosphide, indium phosphide, cadmium sulfide, cadmium selenide, lead sulfide, copper oxide, copper selenide, gallium phosphide, mercury sulfide, mercury selenide, zirconium oxide, zinc oxide, zinc sulfide, zinc selenide, zinc silicate, titanium sulfide, titanium oxide, and tin oxide.

28. The device of claim 26, wherein the phosphors comprise at least one of a rare-earth doped metal oxide including Y₂O₃:

Tb, Y₂O₃;

Eu³⁺, Lu₂O₃;

Eu³⁺, CaTiO₃;

Pr³⁺, CaO;

Er³⁺, (GdZn)O;

Eu³⁺, Sr₄Al₁₄O₂₅;

Eu³⁺, GdMgB₃O₁₀;

Ce³⁺;

Tb³⁺, CeMgAl₁lO₁₉;

Ce³⁺;

Tb³⁺, Y₂O₃;

Eu³⁺, a rare-earth doped yttrium aluminum garnet (YAG) including YAG;

Ce³⁺, a rare-earth doped zirconium oxide including ZrO₂;

Sm³⁺ and ZrO₂;

Er³⁺, rare earth doped vanadates and phosphates including (YVO₄;

Eu) and (La, Ce, Tb)PO₄, doped materials having a host matrix including one Gd₂O₃, GdO₂S, PbO, ZnO, ZnS, and ZnSe and including one of a dopant of Eu, Tb, Tm and Mn, metal-doped forms of zinc sulfide and zinc selenide including ZnS;

Mn²⁺ and ZnS;

Cu⁺, Zn_0.25Cd_0.75S;

AgCl, metal sulfides including CaS;

Eu²⁺, SrGa₂S₄;

Eu and Ca_wSr_xGa_y(S,Se)_z;

Eu, doped silicates, and metal silicates including Ca₃(Sc,Mg)₂Si₃O₁₂;

Ce and (Ba,Sr)₂SiO₄;

Eu.

29. The device of claim 26, wherein the phosphors comprise at least one of rare-Earth doped YAG, rare-Earth doped ZnS, rare-Earth doped SrGa₂S₄, rare-Earth doped ZnSe, rare-Earth doped silicates, and sulfoselenides.

30. The device of claim 26, wherein the phosphor comprises a nano-phosphor.

31. The device of claim 1, wherein the mat of reflective fibers reflects at least 70% of all visible light from 400 nm to 720 nm.

32. The device of claim 1, wherein the mat of reflective fibers reflects at least 80% of said visible light from 400 nm to 720 nm.

33. The device of claim 1, wherein the mat of reflective fibers reflects at least 90% of said visible light from 400 nm to 720 nm.

55. The device of claim 1, wherein the fibers have a length to diameter aspect ratio greater than 500,000:

1 and less than 100,000,000;

1.

58. The device of claim 1, wherein the fibers comprise chopped fibers having a divided length from an original length before incorporation in said mat.

34. A lighting device comprising:

a housing;

a source configured to generate primary light and direct the primary light into the housing;

a reflective mat of fibers disposed inside the housing at a position to reflect the primary light, said fibers layered upon each other in a random manner to form a structure which diffusively reflects at least 70% of incident visible light; and

a light exit in the housing configured to emanate the reflected light from the housing.

35. The device of claim 34, further comprising a luminescent sheet disposed at a position in the housing to emit secondary light upon receiving primary light.

36. The device of claim 35, wherein the light emanated from the light exit has a color rendering index greater than 80.

37. The device of claim 34, wherein the mat of reflective fibers reflects said incident visible light backwards.

38. The device of claim 34, wherein the reflective fibers comprise a dielectric material having an index of refraction greater than 1.6.

39. The device of claim 37 wherein the dielectric material comprises at least one of BaSO₄, ZnO, TiO₂, and Al₂O₃.

40. The device of claim 34, wherein the mat of reflective fibers comprises a reflective material having a reflectivity greater than 0.80.

41. The device of claim 34, wherein the fibers comprise flat-shaped nanofibers comprising a laterally extending surface for reflection of the light.

42. The device of claim 41, wherein the laterally extending surface comprises a surface with a lateral extension of 1 micron.

43. The device of claim 41, wherein the laterally extending surface comprises a surface with a lateral extension of 10 microns.

44. The device of claim 41, wherein the laterally extending surface comprises a surface with a lateral extension of 20 microns.

45. The device of claim 41, wherein the laterally extending surface comprises a surface with a lateral extension of 50 microns.

56. The device of claim 34, wherein the fibers have a length to diameter aspect ratio greater than 500,000:

1 and less than 100,000,000;

1.

59. The device of claim 34, wherein the fibers comprise chopped fibers having a divided length from an original length before incorporation in said mat.

46. A lighting device insert comprising:

a reflective mat of fibers for insertion in a lighting device at a position; and

said fibers layered upon each other in a random manner to form a structure which diffusively reflects at least 70% of incident visible light.

47. The insert of claim 46, wherein the fibers comprise a dielectric material having an index of refraction greater than 1.6.

48. The insert of claim 47, wherein the dielectric material comprises at least one of BaSO₄, ZnO, TiO₂, and Al₂O₃.

49. The insert of claim 46, wherein the mat of reflective fibers comprises a reflective material having a reflectivity greater than 0.80.

50. The insert of claim 46, wherein the fibers comprise flat-shaped nanofibers comprising a laterally extending surface for reflection of the light.

51. The insert of claim 50, wherein the laterally extending surface comprises a surface with a lateral extension of 1 micron.

52. The insert of claim 50, wherein the laterally extending surface comprises a surface with a lateral extension of 10 microns.

53. The insert of claim 50, wherein the laterally extending surface comprises a surface with a lateral extension of 20 microns.

54. The insert of claim 50, wherein the laterally extending surface comprises a surface with a lateral extension of 50 microns.

57. The insert of claim 50, wherein the fibers have a length to diameter aspect ratio greater than 500,000:

1 and less than 100,000,000;

1.

60. The insert of claim 50, wherein the fibers comprise chopped fibers having a divided length from an original length before incorporation in said mat.