Illumination Device with Light Emitting Diodes

• US 20090103296A1
• Filed: 10/10/2008
• Published: 04/23/2009
• Est. Priority Date: 10/17/2007
• Status: Active Grant

• Current Assignee: SBC Xicato Corporation
• Original Assignee: Xicato, Inc.
• Inventors: Harbers, Gerard, Pugh, Mark A., Tseng, Peter K., de Roos, Menne T., Yriberri, John S.
• Granted Patent: US 9,086,213 B2
• Time in Patent Office: Days
• US Class Current: 362/234
• CPC Class Codes: F21K 9/233 specially adapted for generating a spot light distribution, e.g. for substitution of reflector lamps
• CPC Class Codes: F21K 9/62 using mixing chambers, e.g. housings with reflective walls
• 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: F21V 23/0457 the sensor sensing the operating status of the lighting device, e.g. to detect failure of a light source or to provide feedback to the device
• CPC Class Codes: F21V 29/713 in direct thermal and mechanical contact of each other to form a single system
• CPC Class Codes: F21V 29/773 the planes containing the fins or blades having the direction of the light emitting axis
• CPC Class Codes: F21V 29/80 with pins or wires
• CPC Class Codes: F21V 29/83 the elements having apertures, ducts or channels, e.g. heat radiation holes
• CPC Class Codes: F21V 7/26 the material comprising photoluminescent substances
• CPC Class Codes: F21V 7/30 the coatings comprising photoluminescent substances
• CPC Class Codes: F21Y 2103/33 annular
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H05K 1/0206 by printed thermal vias

Abstract

A light emitting device is produced using a plurality of light emitting diodes within a light mixing cavity formed by surrounding sidewalls. The sidewalls may be integrally formed as part of a surrounding heat sink or alternatively may be an insert into a cavity within a heat sink. The reflective sidewalls may be coated with a diffusing material and/or covered with one or more phosphors. Multiple phosphors are located at different locations of the cavity, e.g., on the sidewalls, a window covering the output port, or on a reflector attached to the bottom of the cavity. The light emitting diodes may be positioned rotationally symmetrically around the optical axis on a board.

Claims

1. An apparatus comprising:

a circuit board having a top surface and a bottom surface opposite the top surface;

at least one light emitting diode mounted on the top surface of the circuit board;

a first set of thermal contact areas on the bottom surface of the circuit board; and

a second set of thermal contact areas on the top surface of the circuit board,

wherein the second set of thermal contact areas are exposed adjacent to the light emitting diodes.

2. The apparatus of claim 1, wherein the at least one light emitting diode is at least one packaged light emitting diode.

3. The apparatus of claim 1, wherein the at least one light emitting diode is a plurality of light emitting diodes having p-n junctions that are arranged equidistant from a center position.

4. The apparatus of claim 1, wherein the first set of thermal contact areas are contiguous and wherein the second set of thermal contact areas are contiguous.

5. The apparatus of claim 1, wherein the first set of thermal contact areas have a combined contact area of at least 25 mm² per electrical watt input power going into the at least one light emitting diode and the second set of thermal contact areas have a combined contact area of at least 25 mm² per electrical watt input power going into the at least one light emitting diode.

6. The apparatus of claim 1, wherein the first set of thermal contact areas and the second set of thermal contact areas include at least one of gold and copper and are at least 30 μ

m thick.

7. The apparatus of claim 1, further comprising a plurality of vias through the circuit board.

8. The apparatus of claim 1, wherein the at least one light emitting diode is a plurality of light emitting diodes, the circuit board comprising a central aperture, the central aperture being positioned in the center of the plurality of light emitting diodes, the central aperture having sidewalls that are plated with at least one of copper or aluminum.

9. The apparatus of claim 1, further comprising a light detector mounted on the top surface of the board at the center position.

10. The apparatus of claim 1, further comprising a reflective coating on the top surface of the circuit board.

11. The apparatus of claim 10, wherein the reflective coating comprises a white diffuse paint.

12. The apparatus of claim 11, wherein the white diffuse paint comprises at least one of TiO2, ZnO, or BaSO4 particles.

13. The apparatus of claim 1, further comprising a reflective plate coupled to the top surface of the circuit board;

the reflective plate being configured so that light emitted from the at least one light emitting diode is unobstructed.

14. The apparatus of claim 13, wherein the at least one light emitting diode has a top surface and the reflective plate is coupled to the top surface of the circuit board so that a top surface of the reflective plate is no more than 0.2 mm higher than the top surface of the at least one light emitting diode.

15. The apparatus of claim 1, further comprising a first heat sink thermally coupled to the first set of thermal contact areas on the bottom surface of the circuit board and a second heat sink thermally coupled to the second set of thermal contact areas on the top surface of the circuit board.

16. The apparatus of claim 15, wherein the second heat sink comprises a top surface and a bottom surface and an aperture from the top surface to the bottom surface, the second heat sink being positioned relative to the circuit board and the at least one light emitting diode so that light emitted by the at least one light emitting diode passes through the aperture.

17. The apparatus of claim 16, wherein the aperture comprises reflective sidewalls.

18. The apparatus of claim 16, further comprising a reflective sidewall insert that is mounted inside the aperture.

19. The apparatus of claim 16, further comprising a window coupled to the second heat sink covering the aperture.

20. The apparatus of claim 19, further comprising a wavelength converting material layer on the window.

21. The apparatus of claim 16, further comprising a first type of wavelength converting material covering a first area of the reflective sidewalls of the aperture.

22. The apparatus of claim 21, further comprising a second type of wavelength converting material covering a second area of the reflective sidewalls of the aperture, the second area being a different than the first area

23. The apparatus of claim 16, further comprising a reflector that is coupled to the top surface of the second heat sink, the reflector having an entrance port that is aligned with the aperture in the second heat sink.

24. The apparatus of claim 23, wherein the reflector is coupled to the second heat sink by at least one of a screw or clamps.

25. A light emitting diode illumination device comprising:

a circuit board having a top surface and a bottom surface opposite the top surface, the circuit board having a first thermal contact area on the bottom surface and a second thermal contact area on the top surface;

at least one light emitting diode mounted on the top surface of the circuit board;

a first heat sink thermally coupled to the first thermal contact area on the bottom surface of the circuit board; and

a second heat sink thermally coupled to the second thermal contact area on the top surface of the circuit board, the second heat sink comprising a top surface and a bottom surface and an aperture from the top surface to the bottom surface, and reflective sidewalls inside the aperture, the second heat sink being positioned relative to the at least one light emitting diode mounted so that light emitted by the at least one light emitting diode passes through the aperture.

26. The light emitting diode illumination device of claim 25, wherein the at least one light emitting diode is at least one packaged light emitting diode.

27. The light emitting diode illumination device of claim 25, further comprising a reflective sidewall insert that is mounted inside the aperture to provide the reflective sidewalls inside the aperture.

28. The light emitting diode illumination device of claim 27, further comprising a window coupled to the reflective sidewall insert.

29. The light emitting diode illumination device of claim 28, further comprising a wavelength converting material layer on the window.

30. The light emitting diode illumination device of claim 25, further comprising a first type of wavelength converting material covering a first area of the reflective sidewalls inside the aperture.

31. The light emitting diode illumination device of claim 30, further comprising a second type of wavelength converting material covering a second area of the reflective sidewalls inside the aperture, the second area being a different than the first area.

32. The light emitting diode illumination device of claim 25, further comprising a reflector that is coupled to the top surface of the second heat sink, the reflector having an entrance port that is aligned with the aperture in the second heat sink.

33. A light emitting diode illumination device comprising:

a mounting board having electrical connections;

at least one light emitting diode mounted on the mounting board and coupled to the electrical connections;

at least one reflective sidewall coupled to the mounting board and configured to define a cavity surrounding the at least one light emitting diode;

a first type of wavelength converting material covering a first area of the cavity that is exposed to light produced by the at least one light emitting diode; and

a second type of wavelength converting material covering a second area of the cavity that is exposed to light produced by the at least one light emitting diode, wherein the first area and the second area are different, wherein light produced by the first type of wavelength converting material and light produced by the second type of wavelength converting material is combined in the cavity; and

an output port through which the combined light is transmitted.

34. The light emitting diode illumination device of claim 33, wherein the at least one reflective sidewall defines the output port.

35. The light emitting diode illumination device of claim 33, further comprising a window over the output port.

36. The light emitting diode illumination device of claim 35, wherein the second area is on the window.

37. The light emitting diode illumination device of claim 35, wherein the second type of wavelength converting material on the window outside the cavity.

38. The light emitting diode illumination device of claim 33, further comprising a third type of wavelength converting material covering a third area of the cavity that is exposed to light produced by the at least one light emitting diode, wherein the third area is different than the first area and the second area.

39. The light emitting diode illumination device of claim 33, wherein the at least one reflective sidewall has at least one of an elliptical and polygonal configuration.

40. The light emitting diode illumination device of claim 33, wherein the at least one reflective sidewall comprises aluminum.

41. The light emitting diode illumination device of claim 33, wherein the at least one reflective sidewall comprises a reflective coating.

42. The light emitting diode illumination device of claim 41, wherein the reflective coating comprises a reflective powder that is coupled to the at least one reflective sidewall by one of a powder coating or in a binder.

43. The light emitting diode illumination device of claim 42, wherein the binder comprises at least one of epoxy, silicone, acrylic, or N-Methylpyrrolidone (NMP) materials.

44. The light emitting diode illumination device of claim 42, wherein the reflective powder comprises at least one of TiO2, ZnO, and BaSO4 particles.

45. The light emitting diode illumination device of claim 33, wherein the output port has at least one of an elliptical and polygonal configuration.

46. The light emitting diode illumination device of claim 33, wherein the output port has a diameter of between 10 and 100 mm.

47. The light emitting diode illumination device of claim 35, wherein the window includes a layer of a reflective powder that is coupled to the window by one of a powder coating or in a binder.

48. The light emitting diode illumination device of claim 47, wherein the reflective powder comprises at least one of TiO2, ZnO, and BaSO4 particles.

49. The light emitting diode illumination device of claim 35, wherein the window includes a layer of a dichroic coating

50. The light emitting diode illumination device of claim 49, wherein the dichroic coating has a higher average transmission for light with a wavelength of 500 nm or higher than for light with a wavelength of 500 nm or lower.

51. The light emitting diode illumination device of claim 33, further comprising a collimating element coupled to the at least one reflective sidewall, the collimating element having an input opening that is aligned with the output port.

52. The light emitting diode illumination device of claim 51, wherein the collimating element is removably coupled to the at least one reflective sidewall by at least one of a screw and a clamp.

53. The light emitting diode illumination device of claim 51, wherein the collimating element is a reflector having a truncated compound parabolic shape.

54. The light emitting diode illumination device of claim 33, wherein the at least one light emitting diode comprises at least one packaged light emitting diode.

55. The light emitting diode illumination device of claim 33, wherein the first area and second area are on the at least one reflective sidewall.

56. A light emitting diode illumination device comprising:

a mounting board having electrical connections;

a heat sink thermally coupled to the mounting board;

a plurality of light emitting diodes mounted on the mounting board and coupled to the electrical connections, wherein the light emitted by the plurality of light emitting diodes is emitted into a non-solid material;

a light mixing cavity having a circular configuration defined by at least one reflective sidewall coupled to the mounting board, wherein p-n junctions of the plurality of light emitting diodes are approximately equidistant from a center of the light mixing cavity, and wherein the light from the plurality of light emitting diodes is received and combined by the light mixing cavity;

a window covering an output port through which light from the light mixing cavity is transmitted; and

an optical element coupled to the output port.

57. The light emitting diode illumination device of claim 56, wherein the optical element is one of a reflector and a diffuser.

58. The light emitting diode illumination device of claim 56, further comprising a first type of wavelength converting material covering a first area of the cavity and a second type of wavelength converting material covering a second area of the cavity, the second area being a different than the first area.

59. The light emitting diode illumination device of claim 56, further comprising a reflective insert element that is positioned within the cavity to form the at least one reflective sidewall.

60. The light emitting diode illumination device of claim 56, wherein the at least one reflective sidewall comprises a reflective coating that is coupled to the at least one reflective sidewall by one of a powder coating or in a binder.

61. The light emitting diode illumination device of claim 60, wherein the binder comprises at least one of epoxy, silicone, acrylic, or N-Methylpyrrolidone (NMP) materials.

62. The light emitting diode illumination device of claim 60, wherein the reflective powder comprises at least one of TiO2, ZnO, and BaSO4 particles.

63. The light emitting diode illumination device of claim 56, wherein the output port has at least one of an elliptical and polygonal configuration.

64. The light emitting diode illumination device of claim 56, wherein the window includes a layer of wavelength converting material.

65. The light emitting diode illumination device of claim 64, wherein the layer of wavelength converting material partially covers the window.

66. The light emitting diode illumination device of claim 56, wherein the window includes a layer of a reflective powder that is coupled to the window by one of a powder coating or in a binder.

67. The light emitting diode illumination device of claim 66, wherein the reflective powder comprises at least one of TiO2, ZnO, and BaSO4 particles.

68. The light emitting diode illumination device of claim 56, wherein the window includes a layer of a dichroic coating

69. The light emitting diode illumination device of claim 68, wherein the dichroic coating has a higher average transmission for light with a wavelength of 500 nm or higher than for light with a wavelength of 500 nm or lower.

70. The light emitting diode illumination device of claim 56, further comprising a central reflective element coupled to a center position of the mounting board, the central reflective element extending from the mounting board towards the window.

71. The light emitting diode illumination device of claim 70, wherein the central reflective element has one of a conical and a dome shape.

72. The light emitting diode illumination device of claim 56, wherein a first area of the central reflective element is covered with a first type of wavelength converting material and a second area of the central reflective element is covered with a second type of wavelength converting material, the second area being a different than the first area.

73. The light emitting diode illumination device of claim 56, wherein the light mixing cavity has a first cross-sectional area proximate to the plurality of light emitting diodes and a second cross sectional area distal to the plurality of light emitting diodes, wherein the first cross-sectional area is different than the second cross-sectional area.

74. The light emitting diode illumination device of claim 73, wherein the first cross-sectional area is greater than the second cross-sectional area.

75. The light emitting diode illumination device of claim 56, wherein the plurality of light emitting diodes comprises a plurality of packaged light emitting diodes.

76. A light emitting diode illumination device comprising:

a mounting board having electrical connections;

at least one light emitting diode mounted on the mounting board and coupled to the electrical connections;

at least one sidewall coupled to the mounting board and configured to define a cavity into which light from the at least one light emitting diode is emitted;

a reflective insert element that is positioned within the cavity to form reflective sidewalls within the cavity;

at least one type of wavelength converting material on the reflective sidewalls of the reflective insert element; and

an output port through which light inside the cavity is transmitted.

77. The light emitting diode illumination device of claim 76, wherein the at least one light emitting diode comprises at least one packaged light emitting diode.

78. The light emitting diode illumination device of claim 76, wherein the at least one type of wavelength converting material comprises a first type of wavelength converting material covering a first area of the reflective sidewalls of the reflective insert element, the first area being less than the total area of the reflective insert element.

79. The light emitting diode illumination device of claim 78, further comprising a second type of wavelength converting material covering a second area of the reflective sidewalls of the reflective insert element, the second area being different than the first area.

80. The light emitting diode illumination device of claim 76, further comprising a window over the output port.

81. The light emitting diode illumination device of claim 80, further comprising a wavelength converting material on the window.

82. The light emitting diode illumination device of claim 76, wherein the at least one reflective sidewall has at least one of an elliptical and polygonal configuration.

83. The light emitting diode illumination device of claim 76, wherein the reflective insert element comprises aluminum.

84. The light emitting diode illumination device of claim 76, wherein the reflective insert element comprises a reflective coating.

85. The light emitting diode illumination device of claim 84, wherein the reflective coating comprises a reflective powder that is coupled to the at least one reflective sidewall by one of a powder coating or in a binder.

86. The light emitting diode illumination device of claim 85, wherein the binder comprises at least one of epoxy, silicone, acrylic, or N-Methylpyrrolidone (NMP) materials.

87. The light emitting diode illumination device of claim 85, wherein the reflective powder comprises at least one of TiO2, ZnO, and BaSO4 particles.

88. The light emitting diode illumination device of claim 76, wherein the output port has at least one of a circular, elliptical, and polygonal configuration.

89. The light emitting diode illumination device of claim 76, wherein the output port has a diameter of between 10 and 100 mm.

90. The light emitting diode illumination device of claim 80, wherein the window includes a layer of a reflective powder that is coupled to the window by one of a powder coating or in a binder.

91. The light emitting diode illumination device of claim 90, wherein the reflective powder comprises at least one of TiO2, ZnO, and BaSO4 particles.

92. The light emitting diode illumination device of claim 79, wherein the window includes a layer of a dichroic coating

93. The light emitting diode illumination device of claim 92, wherein the dichroic coating has a higher average transmission for light with a wavelength of 500 nm or higher than for light with a wavelength of 500 nm or lower.

94. The light emitting diode illumination device of claim 76, further comprising an optical element coupled to the at least one sidewall, the collimating element having an input opening that is aligned with the output port.

95. The light emitting diode illumination device of claim 94, wherein the optical element is removably coupled to the at least one sidewall by at least one of a screw and a clamp.

96. The light emitting diode illumination device of claim 94, wherein the optical element is one of a reflector and a diffuser.

97. The light emitting diode illumination device of claim 76, wherein the mounting board has a top surface and a bottom surface opposite the top surface, the mounting board having a first thermal contact area on the bottom surface and a second thermal contact area on the top surface, the light emitting diode illumination device further comprising:

a first heat sink thermally coupled to the first thermal contact area on the bottom surface of the circuit board; and

a second heat sink thermally coupled to the second thermal contact area on the top surface of the circuit board.

98. The light emitting diode illumination device of claim 97, wherein the second heat sink comprises a top surface and a bottom surface and an aperture from the top surface to the bottom surface that defines the at least one sidewall.

99. The light emitting diode illumination device of claim 81, wherein the at least one type of wavelength converting material is a red phosphor that covers an area of between 35% to 100% of the reflective sidewalls of the reflective insert element and has a concentration of between 0.5% to 19%, and wherein the wavelength converting material on the window is a yellow phosphor and has a concentration of 17% to 32%.