Stimulated lighting devices

• US 8,851,693 B2
• Filed: 04/14/2010
• Issued: 10/07/2014
• Est. Priority Date: 04/15/2009
• Status: Expired due to Fees

• Current Assignee: Research Triangle Institute
• Original Assignee: Research Triangle Institute
• Inventors: Lamvik, Michael Kasper, Davis, James Lynn
• Primary Examiner(s): Mai, Anh
• Assistant Examiner(s): QUARTERMAN, KEVIN J
• Application Number:
  US13/258,212
• Publication Number:
  US 20120033403A1
• Time in Patent Office: 1,637 Days
• Field of Search: 313/498, 313/503, 313/506, 313/512, 313/113, 313/461, 362/2, 362/231, 362/298, 362/301, 362/84, 362/293
• US Class Current: 362/84
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21K 9/68 Details of reflectors forming part of the light source
• CPC Class Codes: F21V 1/17 the material comprising photoluminescent substances
• CPC Class Codes: F21V 13/08 the elements being filters or photoluminescent elements and reflectors
• CPC Class Codes: F21V 3/04 characterised by materials, surface treatments or coatings
• CPC Class Codes: F21V 3/049 Patterns or structured surfaces for diffusing light, e.g. frosted surfaces
• CPC Class Codes: F21V 7/0008 providing for indirect lighting
• CPC Class Codes: F21V 7/24 characterised by the material
• CPC Class Codes: F21V 7/30 the coatings comprising photoluminescent substances
• CPC Class Codes: F21V 9/32 characterised by the arrangement of the photoluminescent material
• CPC Class Codes: F21V 9/38 Combination of two or more photoluminescent elements of different materials
• CPC Class Codes: F21V 9/45 by adjustment of photoluminescent elements
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0061 the light source comprising a LED semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission H01L33/00
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil

Abstract

A stimulated lighting device for stimulatable light emission including a luminescent sheet including light stimulatable particles which emit secondary light upon receiving primary light. The lighting device includes a source configured to generate and direct the primary light obliquely onto the luminescent sheet, at least one reflector configured to reflect at least a part of the primary light and a part of the secondary light onto the luminescent sheet and configured to reflect at least a part of scattered primary light and a part of the secondary light from the luminescent sheet toward the light exit, and a light exit configured to emanate light as a combination of the primary light and the secondary light.

Claims

1. A stimulated lighting device comprising:

a luminescent sheet extending along a longitudinal axis toward a light exit of the device and including light stimulatable particles configured to emit secondary light upon receiving primary light;

a source offset from the longitudinal axis and configured to generate and direct said primary light onto the luminescent sheet;

at least one reflector disposed apart from the luminescent sheet and configured to reflect at least a part of the primary light and a part of the secondary light onto the luminescent sheet and configured to reflect at least a part of scattered primary light and a part of the secondary light from the luminescent sheet toward the light exit; and

said light exit configured to emanate light from the lighting device as a combination of the primary light and the secondary light.

2. The device of claim 1, wherein the part of the secondary light reflected onto the luminescent sheet comprises substantially no reflected light.

3. The device of claim 1, wherein the light emanated from the light exit has a color rendering index greater than 70.

4. The device of claim 1, wherein:

the at least one reflector comprises a reflector disposed on one side of the luminescent sheet; and

the luminescent sheet has a transmittance of less than 40% for the primary light.

5. The device of claim 1, wherein:

the at least one reflector comprises opposite reflectors disposed on opposite sides of the luminescent sheet; and

the luminescent sheet has a transmittance of less than 40% for the primary light.

6. The device of claim 5, wherein the opposite reflectors comprise at least one of planar or curved reflectors.

7. The device of claim 5, wherein the opposite reflectors comprise spherical or cylindrical reflectors.

8. The device of claim 5, wherein the light source comprises at least two light sources disposed respectively on opposite sides of the luminescent sheet.

9. The device of claim 1, wherein:

the at least one reflector comprises opposite reflectors disposed on opposite sides of the luminescent sheet;

the luminescent sheet has a transmittance of greater than 40% for the primary light; and

the light source comprises a light source disposed in a position to illuminate directly only one side of the luminescent sheet.

10. The device of claim 8, wherein the opposite reflectors comprise at least one of planar or curved reflectors.

11. The device of claim 9, wherein the opposite reflectors comprise spherical or cylindrical reflectors.

12. The device of claim 9, wherein the light source is disposed in a wall of one of the opposite reflectors.

13. The device of claim 1, wherein the light source comprises two light sources emitting separate wavelengths of light.

14. The device of claim 1, wherein the luminescent sheet comprises:

nanofibers; and

an optically clear encapsulant securing the nanofibers and the light stimulatable particles.

15. The device of claim 14, wherein the encapsulant has an index of refraction that differs from the material being encapsulated by at least 0.10.

16. The device of claim 1, wherein the at least one reflector comprises at least one of a stamped metal member, a metallized plastic member, nanofiber, or a metallized glass member.

17. The device of claim 1, wherein the light exit comprises a light diffusing material configured to mix the primary light and the secondary light.

18. The device of claim 17, wherein the light diffusing material comprises a frosted optical component configured to mix the primary light and the secondary light.

19. The device of claim 1, wherein the light exit comprises an integrating sphere configured to mix the primary light and the secondary light.

20. The device of claim 1, wherein the source configured to generate said primary light comprises an electrical bulb socket.

21. The device of claim 1 where the luminescent sheet includes a diffuse reflector.

22. The device of claim 1, wherein the luminescent sheet comprises nanofibers having an average fiber diameter in a range between 100 to 5,000 nm.

23. The device of claim 22, wherein the nanofibers have an average fiber diameter is in a range between 300 nm to 3,000 nm.

24. The device of claim 21, wherein the luminescent sheet has a thickness in a range between 0.01 microns and 2,000 microns.

25. The device of claim 1, wherein the luminescent sheet has a thickness in a range between 1 to 500 microns.

26. The device of claim 1, wherein the stimulatable particles comprise luminescent particles.

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

28. The device of claim 27, 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.

29. The device of claim 27, 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⁺, CeMgAl₁1O₁₉;

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, rare-Earth doped silicates, 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, nitrides, metal sulfides including CaS;

Eu²⁺, SrGa₂S₄;

Eu and Ca_wSr_xGa_y(S,Se)_z,;

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

Ce and (Ba,Sr)₂SiO₄;

Eu.

30. The device of claim 27, wherein the phosphors comprise at least one of rare-Earth doped YAG, rare-Earth doped ZnS, rare-Earth doped SrGa₂S₄, rare-Earth doped silicates, and rare-Earth doped ZnSe.

31. The device of claim 27, where the phosphor comprises a nano-phosphor.

32. The device of claim 1, wherein the luminescent sheet comprises a detachable luminescent sheet for replacement thereof.

33. The device of claim 32, further comprising a receptacle for placement of the detachable luminescent sheet in a vicinity of the at least one reflector.

34. A stimulated lighting device comprising:

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

a light source configured to generate and direct said primary light obliquely onto the luminescent sheet;

a light exit configured to emanate light from the lighting device as a combination of the primary light and the secondary light wherein;

at least one reflector configured to reflect at least a part of the primary light and a part of the secondary light onto the luminescent sheet and configured to reflect at least a part of scattered primary light and a part of the secondary light from the luminescent sheet toward the light exit;

the at least one reflector comprises opposite reflectors disposed on opposite sides of the luminescent sheet;

the light source comprises two light sources disposed on opposite sides of the luminescent sheet; and

a reflecting layer is disposed as a central layer between two exposed sides of the luminescent sheet.

35. The device of claim 34, wherein the two reflectors comprise at least one of planar or curved reflectors.

36. The device of claim 34, wherein the two reflectors comprise spherical or cylindrical reflectors.

37. The device of claim 34, wherein the luminescent sheet comprises layers of photoluminescent materials, where respective layers are configured to produce different colors upon interaction with the primary light.

38. A stimulated lighting device comprising:

a reflective housing;

a luminescent sheet extending along a longitudinal axis toward a light exit of the device, disposed apart from the reflective housing, and disposed inside the reflective housing and configured to emit secondary light upon receiving primary light;

a source offset from the longitudinal axis and configured to generate and direct said primary light onto the luminescent sheet; and

said light exit in the reflective housing configured to emanate light from the reflective housing as a combination of the primary light and the secondary light.

39. The device of claim 38, wherein the light emanated from the light exit has a color rendering index greater than 70.

40. The device of claim 38, wherein the light emanated from the light exit has a color rendering index greater than 80.

41. The device of claim 38, wherein the luminescent sheet is disposed at a center of the reflective housing.

42. The device of claim 38, wherein the luminescent sheet extends at least part of the way to a bottom of the reflective housing opposite the light exit.

43. The device of claim 38, wherein the luminescent sheet is disposed at one end of the reflective housing.

44. The device of claim 43, wherein the luminescent sheet extends at least part of the way across one end of the reflective housing.

45. The device of claim 38, wherein:

the luminescent sheet has a transmittance of less than 40% for the primary light; and

the light source comprises two light sources disposed on the same side of the luminescent sheet.

46. The device of claim 38, wherein:

the luminescent sheet has a transmittance of less than 40% for the primary light; and

the light source comprises two light sources disposed on opposite sides of the luminescent sheet.

47. The device of claim 38, wherein:

the luminescent sheet has a transmittance of greater than 40% for the primary light; and

the light source comprises a light source disposed in position to illuminate directly only one side of the luminescent sheet.

48. The device of claim 38, wherein the reflective housing comprises at least one of planar or curved reflectors.

49. The device of claim 38, wherein the reflective housing comprises spherical or cylindrical reflectors.

50. The device of claim 38, wherein the luminescent sheet comprises a detachable luminescent sheet for replacement thereof.

51. The device of claim 50, further comprising a receptacle for placement of the detachable luminescent sheet in a vicinity of the at least one reflector.

52. A stimulated lighting device comprising:

a reflective housing;

a luminescent sheet disposed in the reflective housing and configured to emit secondary light upon receiving primary light;

a source configured to generate and direct said primary light obliquely onto the luminescent sheet;

a light exit in the reflective housing configured to emanate light from the reflective housing as a combination of the primary light and the secondary light; and

a reflecting layer disposed as a central layer between two exposed sides of the luminescent sheet.

53. A method of treating a luminescent sheet to increase a quantum emission efficiency of the luminescent sheet, comprising:

exposing photoluminescent nanofibers in the luminescent sheet to actinic radiation; and

thereby

increasing the quantum emission efficiency of the luminescent sheet.

54. The method of claim 53, wherein exposing comprises:

exposing the photoluminescent nanofibers in the luminescent sheet to radiation from 350-490 nm at an optical power of 0.5 μ

W/cm² or higher.

55. The method of claim 53, wherein exposing comprises:

exposing the photoluminescent nanofibers in the luminescent sheet for a period between 1 and 48 hours.

56. The method of claim 53, wherein further comprising:

prior to exposing, at least one of dip coating, drop coating, spray coating, ink-jet printing, screen printing, or spin coating photoluminescent particles onto the luminescent sheet; and

drying the luminescent sheet.