Non-uniform diffuser to scatter light into uniform emission pattern

• US 9,310,030 B2
• Filed: 10/08/2010
• Issued: 04/12/2016
• Est. Priority Date: 03/03/2010
• Status: Active Grant

• Current Assignee: IDEAL Industries Lighting, LLC (Ideal Industries Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Tong, Tao, Letoquin, Ronan, Keller, Bernd, Tarsa, Eric, Youmans, Mark, Lowes, Theodore, Medendorp, Nicholas W. Jr., Van De Ven, Antony, Negley, Gerald, Guschl, Peter, Yuan, Zongjie
• Primary Examiner(s): Mai, Anh
• Assistant Examiner(s): APENTENG, JESSICA MCMILLAN
• Application Number:
  US12/901,405
• Publication Number:
  US 20110216523A1
• Time in Patent Office: 2,013 Days
• Field of Search: 362/84, 362/800, 362/231, 362/235, 362/294, 362/373, 362/293, 362/311.06
• US Class Current: 1/1
• CPC Class Codes: F21K 9/232 specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb
• CPC Class Codes: F21K 9/60 Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction
• 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 9/65 specially adapted for changing the characteristics or the distribution of the light, e.g. by adjustment of parts
• CPC Class Codes: F21V 29/505 of reflectors
• CPC Class Codes: F21V 3/12 the coatings comprising photoluminescent substances
• CPC Class Codes: F21V 5/002 using microoptical elements for redirecting or diffusing light
• CPC Class Codes: F21V 5/10 comprising photoluminescent material
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation

Abstract

A lighting device comprising a light source and a diffuser spaced from the light source. The lighting device further comprises a wavelength conversion material disposed between the light source and the diffuser and spaced from the light source and the diffuser, wherein the diffuser is shaped such that there are different distances between the diffuser and said conversion material at different emission angles. In other embodiments the diffuser includes areas with different diffusing characteristics. Some lamps are arranged to meet A19 and Energy Star lighting standards.

Claims

1. A lamp, comprising:

a solid state light source emitting a substantially forward emission pattern;

a diffuser to alter said forward emission pattern so that said lamp emits an emission pattern comprising greater uniformity than said forward emission pattern;

wherein the diffuser comprises a plurality of diffuser attributes that are used to control a desired emission profile for the lamp; and

wherein said diffuser comprises varying scattering properties over its surface based on the desired emission profile for the lamp.

2. The lamp of claim 1, wherein said substantially forward emission pattern comprises a substantially Lambertian emission pattern.

3. The lamp of claim 1, wherein said light source is substantially planar.

4. The lamp of claim 1, wherein said substantially uniform emission pattern is substantially omnidirectional.

5. The lamp of claim 1, wherein said diffuser comprises varying scattering properties along at least one dimension of the diffuser.

6. The lamp of claim 5, wherein said varying scattering properties comprises varying scattering surface properties, or varying volume of scattering materials.

7. The lamp of claim 5, wherein said varying scattering properties comprise higher diffuser scattering power in the axis of said light source emission comprising a higher light intensity, and lower diffuser scattering power in the axis of said light source emission comprising a lower light intensity.

8. The lamp of claim 1, wherein said light source is a solid state light source.

9. The lamp of claim 1, further comprising a wavelength conversion element in the light path between said light source and diffuser.

10. The lamp of claim 9, wherein said conversion element comprises a transparent phosphor carrier.

11. The lamp of claim 9, wherein said wavelength conversion element comprises a phosphor carrier comprising a transparent, thermally conductive material.

12. The lamp of claim 9, wherein said conversion element is three-dimensional.

13. The lamp of claim 12, wherein said conversion element is substantially rotationally symmetric.

14. The lamp of claim 12, wherein said conversion element is a substantially linear diffuser dome.

15. The lamp claim 9, wherein said conversion element is planar.

16. The lamp of claim 1, wherein said diffuser comprises a diffuser dome.

17. The lamp of claim 1, wherein said diffuser comprises a rotationally symmetric diffuser dome.

18. The lamp of claim 1, wherein said diffuser comprises a substantially linear diffuser dome.

19. The lamp of claim 1, wherein said diffuser comprises a diffusing material, wherein said diffuser comprises one or more areas covered by a greater amount of diffusing material.

20. The lamp of claim 1, further comprising heat dissipation elements to conduct conversion heat away from said wavelength conversion material.

21. The lamp of claim 1, wherein said light source comprises a plurality of co-planar light emitting diodes (LEDs).

22. The lamp of claim 1, wherein the light emitted from the diffuser comprises a spatial uniformity that is within 40% of a mean value within a range of viewing angles.

23. The lamp of claim 1, wherein the light emitted from the diffuser comprises a spatial uniformity that is within 20% of a mean value within a range of viewing angles.

24. A lamp, comprising:

a light source; and

an optical element at least partially covering said light source so that at least some light from said light source passes through said optical element, said optical element comprising scattering properties that vary along at least one dimension of the element to modify the emission distribution of the light emitted by said light source, said optical element comprising a plurality of diffuser attributes including said scattering properties, wherein said diffuser attributes are used to control a desired emission profile for the lamp.

25. The lamp of claim 24, wherein said optical element modifies angular distribution of light emitted by said light source.

26. The lamp of claim 24, wherein said light source emits light with a substantially non-uniform emission distribution, said optical element modifying said substantially non-uniform distribution to a substantially uniform distribution.

27. The lamp of claim 24, wherein said light source emits a substantially Lambertian emission pattern, said optical element modifying said substantially Lambertian emission pattern to a substantially uniform emission pattern.

28. The lamp of claim 24 wherein said optical element comprises a diffuser comprising varying scattering properties.

29. The lamp of claim 28, wherein said diffuser comprises varying scattering properties along one dimension of the diffuser.

30. The lamp of claim 24, wherein said light source is a solid state light source.

31. The lamp of claim 24, further comprising a wavelength conversion element in the light path between said light source and diffuser.

32. The lamp of claim 31, wherein said conversion element comprises a phosphor carrier.

33. The lamp of claim 31, wherein said conversion element is three-dimensional.

34. The lamp claim 31, wherein said conversion element is planar.

35. The lamp of claim 31, wherein said conversion element is substantially rotationally symmetric.

36. The lamp of claim 24, wherein said optical element comprises a diffuser.

37. The lamp of claim 36, wherein said diffuser is substantially rotationally symmetric.

38. The lamp of claim 24, wherein the light emitted from the optical element comprises a spatial uniformity that is within 40% of a mean value within a range of viewing angles.

39. The lamp of claim 24, wherein the light emitted from the optical element comprises a spatial uniformity that is within 20% of a mean value within a range of viewing angles.

40. The lamp of claim 24, wherein said varying scattering properties comprise higher diffuser scattering power in the axis of said light source emission comprising a higher light intensity, and lower diffuser scattering power in the axis of said light source emission comprising a lower light intensity.

41. A lighting device comprising:

a light source;

a diffuser spaced from and in the light path of the light source; and

a wavelength conversion element between the light source and the diffuser and spaced from the light source and the diffuser, wherein said diffuser is shaped such that there are different distances between said diffuser and said conversion material at different emission angles;

wherein said diffuser comprises diffusing properties that vary across one or more areas of the diffuser based on the desired emission profile for the lighting device.

42. The lighting device of claim 41, wherein said light source is a solid state light source.

43. The lighting device of claim 41, wherein said wavelength conversion element comprises a phosphor carrier comprising a thermally conductive material.

44. The lighting device of claim 41, wherein said diffuser comprises a diffuser dome.

45. The lighting device of claim 41, wherein said diffuser is substantially rotationally symmetric.

46. The lighting device of claim 41, wherein said diffuser comprises a diffusing material, wherein said diffuser incorporates one or more areas with varying diffusing properties.

47. The lighting device of claim 41, wherein said diffuser disperses light from said light source and/or said wavelength conversion material.

48. The lighting device of claim 41, further comprising heat dissipation elements to conduct conversion heat away from said wavelength conversion element.

49. The lighting device of claim 41, wherein said wavelength conversion element is three-dimensional.

50. The lighting device of claim 41, wherein said wavelength conversion element is planar.

51. The lighting device of claim 41, wherein said conversion element is substantially rotationally symmetric.

52. The lighting device of claim 41, wherein said light source comprises a plurality of co-planar light emitting diodes (LEDs).

53. The lighting device of claim 41, wherein said light source comprises a plurality of non-co-planar light emitting diodes (LEDs).

54. The lighting device of claim 41, wherein the space between said light source and said wavelength conversion material and the space between said diffuser and said phosphor comprise light mixing chambers.

55. The lighting device of claim 41, wherein said diffuser at least partially conceals the appearance of said wavelength conversion material when said lighting device is not operating.

56. The lighting device of claim 41, wherein said diffuser exhibits a substantially white appearance when said lighting device is not operating.

57. The lighting device of claim 41, providing a steady state lumen output of at least 800 lumens.

58. The lighting device of claim 41, comprising emission efficiency of greater than 50 lumens per watt.

59. The lighting device of claim 41, wherein said light source comprises 10 or fewer light emitting diodes.

60. The lighting device of claim 41, wherein said light source comprises a light emitting chip area of 10 mm² or less.

61. The lighting device of claim 41, emitting light with a color render index (CRI) greater than 80.

62. The lighting device of claim 41, wherein the light emitted from the diffuser comprises a spatial uniformity that is within 40% of a mean value within a range of viewing angles.

63. The lighting device of claim 62, wherein said range of viewing angles is 0 to 135°

.

64. The lighting device of claim 41, wherein the light emitted from the diffuser comprises a spatial uniformity that is within 20% of a mean value within a range of viewing angles.

65. The lighting device of claim 64, wherein said range of viewing angles is 0 to 135°

.

66. The lighting device of claim 41, wherein the light emitted from the diffuser comprises a color uniformity that is within a standard deviation on a CIE diagram within a range of viewing angles.

67. The lighting device of claim 66, wherein the standard deviation is a 4-step MacAdams ellipse.

68. The lighting device of claim 66, wherein said range of viewing angles is 0 to 135°

.

69. A lighting device comprising:

a light source;

a diffuser spaced from the light source, said diffuser comprising areas with different diffusing characteristics, said areas comprising scattering elements that comprise varying scattering properties based on the desired emission profile for the lighting device; and

a wavelength conversion element between the light source and the diffuser and spaced from the light source and the diffuser.

70. The light emitting device of claim 69, wherein said different diffusing characteristics are provided by areas comprising differing amounts of diffusing material.

71. The lighting device of claim 70, wherein said diffuser is rotationally symmetric.

72. The light emitting device of claim 69, wherein said different diffusing characteristics comprise differing amounts of diffusing characteristics.

73. The light emitting diode of claim 69, wherein said diffuser comprises a differing amount of diffusing material at a viewing angle 0 and 45 degrees viewing angle.

74. The light emitting device of claim 69, wherein said diffuser is shaped such that there are different distances between said diffuser and said conversion element at different emission angles.

75. The lighting device of claim 69, wherein said diffuser comprises a diffuser dome.

76. The lighting device of claim 69, wherein the conversion and/or scattering properties of said conversion element vary across its surface.

77. A lamp, comprising:

a solid state light source emitting in an emission pattern; and

a diffuser to alter said light source emission pattern so that said lamp emits a emission pattern comprising greater uniformity than said light source emission pattern, said diffuser being shaped with a lateral area comprising a smaller radius of curvature than a top area of said diffuser,

wherein said diffuser comprises varying scattering properties based on the desired emission profile for the lamp.

78. A lighting device comprising:

a solid state light source;

a diffuser spaced from and in the light path of the light source; and

a wavelength conversion element between the light source and the diffuser and spaced from the light source and the diffuser, wherein said conversion element comprises varying scattering properties and said diffuser comprises varying scattering properties based on the desired emission profile for the lighting device, wherein said lighting device emits a more uniform pattern than would be emitted by said conversion element or said diffuser diffusing said light source light without the other.