Light emitting diode packages

• US 7,648,257 B2
• Filed: 04/21/2006
• Issued: 01/19/2010
• Est. Priority Date: 04/21/2006
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Villard, Russell G.
• Primary Examiner(s): Truong; Bao Q
• Application Number:
  US11/379,709
• Publication Number:
  US 20070247847A1
• Time in Patent Office: 1,369 Days
• Field of Search: 362/294, 362/547, 362/373, 362/580, 362/126, 362/218, 362/264, 362/345, 362/230, 362/249.02, 257/712, 257717-722, 165/80.3, 165/185
• US Class Current: 362/294
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: F21Y 2103/10 comprising a linear array of point-like light-generating elements
• CPC Class Codes: F21Y 2105/10 comprising a two-dimensional array of point-like light-generating elements
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/40 Details of LED load circuits

Abstract

Lighting packages are described for light emitting diode (LED) lighting solutions having a wide variety of applications which seek to balance criteria such as heat dissipation, brightness, and color uniformity. The present approach includes a backing of thermally conductive material and two or more arrays of LEDs attached to a printed circuit board (PCB). The PCB is attached to the top surface of the backing and the two or more arrays of LEDs are separated by a selected distance to balance heat dissipation and color uniformity of the LEDs.

Claims

1. A package of light emitting diodes (LEDs) comprising:

a backing of thermally conductive material; and

two or more arrays of LEDs, each array mounted to a printed circuit board (PCB), the PCBs for the two or more arrays attached to the top surface of the backing, said two or more arrays of LEDs separated by a selected distance, d inches apart, where d is approximately equal to 2*(1.25/tan((180−

α

/2)) and α

is the angle of intensity, to balance heat dissipation and color uniformity of the LEDs.

2. The package of claim 1 wherein the backing of thermally conductive material is a planar sheet of aluminum.

3. The package of claim 1 wherein the top surface of the backing has a white color to provide diffuse reflection.

4. The package of claim 1 wherein the package dimensions are 1 foot by 1 foot.

18. The package of claim 1 further comprising a diffuser to form a lighting fixture for room lighting.

5. A package of light emitting diodes (LEDs) comprising:

a backing of thermally conductive material; and

two or more arrays of LEDs, each array mounted to a printed circuit board (PCB), the PCBs for the two or more arrays attached to the top surface of the backing, said two or more arrays of LEDs separated by a selected distance, d inches apart, where d is less than 2*(1.25/tan((180−

α

)/2)) but greater than or equal to the smallest distance for which the backing provides adequate heat dissipation and α

is the angle of intensity, to balance heat dissipation and color uniformity of the LEDs.

6. The package of claim 5 wherein the two or more arrays of LEDs are electrically connected in parallel.

7. The package of claim 5 wherein the two or more arrays of LEDs where the LEDs operate around 350 mAmps of input current and consume approximately 1 Watt of power.

8. The package of claim 5 wherein the backing comprises two or more strips of aluminum attached to two support members forming an opening framed by said strips of aluminum and said support members, the two or more arrays of LEDs attached to the upper surfaces of the two or more strips of aluminum.

9. The package of claim 5 wherein the backing comprises two or more T-shaped aluminum bars attached to two support members, the two or more arrays of LEDs attached to the upper surfaces of the two or more T-shaped aluminum bars.

14. The package of claim 7 wherein the package dimensions are approximately 1 foot by 1 foot.

15. The package of claim 14 wherein three arrays are employed and include a total of at least 30 LEDs.

16. The package of claim 15 wherein during operation at an ambient temperature of approximately 25°

C. the backing reaches a steady state temperature of approximately 55°

C.

17. The package of claim 15 wherein said at least 30 LEDs have a vertical spacing of approximately 1 inch.

10. A module of light emitting diodes (LEDs) comprising:

a plurality of LEDs; and

a T-shaped bar composed of thermally conductive material having a uniform thickness, the T-shaped bar comprising a top member having a width and a center and a substantially perpendicular leg member having a height and located substantially at the center of the top member, the width of the top member being at least equal to the height of the perpendicular leg member, and wherein the plurality of LEDs are mounted above the upper surface of the top member of the T-shaped bar and substantially centered above the perpendicular leg member, whereby heat generated from the plurality of LEDs is dissipated by the T-shaped bar.

11. The module of claim 10 wherein the T-shaped bar is anodized black aluminum.

19. The module of claim 10 wherein the plurality of LEDs are mounted on a printed circuit board attached to the upper surface of the T-shaped bar, the thermally conductive material is aluminum, and the uniform thickness is approximately one-sixteenth of an inch.

20. The module of claim 19 wherein the T-shaped bar has a height of approximately one inch and a width of approximately one to one and one-half inches.

12. A module of light emitting diodes (LEDs) comprising:

a plurality of LEDs;

a T-shaped bar composed of thermally conductive material, the T-shaped bar comprising a top member having a center and a single substantially perpendicular leg member located substantially at the center of the top member;

a printed circuit board (PCB) having the plurality of LEDs attached thereto, the PCB being attached to the upper surface of the top member of the T-shaped bar and substantially centered above the perpendicular leg member to dissipate heat generated from the plurality of LEDs; and

an L-shaped bar having two inner surfaces and a lower outer surface, the T-shaped bar attached to the two inner surfaces of the L-shaped bar.

13. The module of claim 12 further comprising:

a plate; and

a hinge having a top and bottom outer surface, the bottom surface of the L-shaped bar attached to the top outer surface of the hinge, the bottom outer surface of the hinge attached to the plate allowing the T-shaped bar to rotate about the axis of the hinge.