ELECTRICALLY ISOLATED HEAT SINK FOR SOLID-STATE LIGHT

• US 20110026264A1
• Filed: 07/29/2010
• Published: 02/03/2011
• Est. Priority Date: 07/29/2009
• Status: Abandoned Application

• Current Assignee: Express Imaging Systems, LLC
• Original Assignee: Express Imaging Systems, LLC
• Inventors: Reed, William G., Renn, John O.
• Application Number:
  US12/846,516
• Publication Number:
  US 20110026264A1
• Time in Patent Office: Days
• US Class Current: 362/373
• CPC Class Codes: F21V 23/02 the elements being transformers, impedances or power supply units, e.g. a transformer with a rectifier
• CPC Class Codes: F21V 29/71 using a combination of separate elements interconnected by heat-conducting means, e.g. with heat pipes or thermally conductive bars between separate heat-sink elements
• CPC Class Codes: F21V 29/76 with essentially identical parallel planar fins or blades, e.g. with comb-like cross-section
• 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]

Abstract

An illumination device comprises a solid-state light source and a heat transfer structure. The solid-state light source is thermally conductively coupled to the heat transfer structure to dissipate heat thereby. The heat transfer structure includes a first thermally conductive element and a second thermally conductive element. The first thermally conductive element is configured to transfer at least a portion of the heat from the light source to an external ambient environment. The second thermally conductive element is electrically non-conductive and electrically isolates the first thermally conductive element from the light source.

Claims

1. An illumination device, comprising:

a solid-state light source that emits light and heat when powered; and

a passive heat transfer structure to which the solid-state light source is thermally conductively coupled to dissipate a least some of the heat emitted by the solid-state light source, the passive heat transfer structure including;

a heat exchanger that is thermally conductive and electrically conductive, the heat exchanger having a plurality of protrusions that extend into an external ambient environment that surrounds at least a portion of an exterior of the illumination device when the illumination device is in use, the heat exchanger configured to transfer at least a portion of the heat from the solid-state light source to the external ambient environment by convective and radiant heat transfer, and

an intermediate dielectric heat spreader that is thermally conductive and electrically non-conductive, the intermediate dielectric heat spreader having an area greater than an area of the solid-state light source and a periphery that encompasses the area of the intermediate dielectric heat spreader, the intermediate dielectric heat spreader positioned between the solid-state light source and the heat exchanger with a periphery of the solid-state light source encompassed by the periphery of the intermediate dielectric heat spreader such that the intermediate dielectric heat spreader thermally conductively couples the solid-state light source to the heat exchanger and electrically isolates the heat exchanger from the solid-state light source and provides arc over protection between the solid-state light source and the heat exchanger.

2. The illumination device of claim 1 wherein the intermediate dielectric heat spreader is made of a filled polymer material.

3. The illumination device of claim 1 wherein the heat exchanger is made of a filled polymer material.

4. The illumination device of claim 1 wherein at least one of the heat exchanger or the intermediate dielectric heat spreader is a filled polymer overmold of the other one of the heat exchanger or intermediate dielectric heat spreader.

5. The illumination device of claim 1 wherein the heat exchanger has a cavity, and the intermediate dielectric heat spreader is received in the cavity of the heat exchanger.

6. The illumination device of claim 1, further comprising:

a primary heat spreader that is thermally conductive and electrically conductive, the primary heat spreader having an area greater than the area of the solid-state light source and smaller than an area of the intermediate dielectric heat spreader, the primary heat spreader having a periphery that encompasses the area of the primary heat spreader, the primary heat spreader positioned between the solid-state light source and the intermediate dielectric heat spreader to thermally conductively couple the solid-state light source to the heat exchanger via the intermediate dielectric heat spreader.

7. The illumination device of claim 6 wherein the primary heat spreader is a vapor phase heat spreader having at least one channel that carries a heat exchange fluid which undergoes a phase change between a liquid and a vapor as the heat exchange fluid traverses the at least one channel between a relatively warmer portion and a relatively cooler portion of the primary heat spreader.

8. The illumination device of claim 6 wherein the primary heat spreader is a metallic plate.

9. The illumination device of claim 6 wherein the intermediate dielectric heat spreader and the heat exchanger are each made of respective filled polymer materials.

10. The illumination device of claim 9 wherein the intermediate dielectric heat spreader is a filled polymer overmold of the primary heat spreader.

11. The illumination device of claim 10 wherein the heat exchanger is a filled polymer overmold of the intermediate dielectric heat spreader.

12. The illumination device of claim 6 wherein the heat exchanger has a thermal conductivity of at least 20 Watt per meter Kelvin (W/mK), the intermediate dielectric heat spreader has a thermal conductivity of at least 10 W/mK, and the primary heat spreader has a thermal conductivity of at least 1,200 W/mK.

13. The illumination device of claim 6 wherein the solid-state light source includes a plurality of light-emitting diodes (LEDs) bonded to the primary heat spreader by at least one of a metal alloy bond, a thermally conductive adhesive, or a solder bump, the illumination device does not employ any active heat transfer mechanisms, and further comprising:

an electronic ballast coupled to provide regulated electrical power to the solid-state light source;

a housing having a cavity to receive the electronic ballast therein, the housing physically coupled to the heat exchanger to enclose the electronic ballast between the housing and the heat exchanger; and

a substantially transparent cover physically coupled to the heat exchanger to provide environmental protection to the solid-state light source.

14. A method of producing an illumination device, the method comprising:

producing a passive heat transfer structure by;

providing a heat exchanger that is thermally conductive and electrically conductive, the heat exchanger having a plurality of protrusions that extend into an external ambient environment that surrounds at least a portion of an exterior of the illumination device when the illumination device is in use, the heat exchanger configured to transfer at least a portion of the heat from the solid-state light source to the external ambient environment by convective and radiant heat transfer, and

thermally coupling an intermediate dielectric heat spreader that is thermally conductive and electrically non-conductive to the heat exchanger, the intermediate dielectric heat spreader having an area greater than an area of the solid-state light source and a periphery that encompasses the area of the intermediate dielectric heat spreader;

thermally conductively coupling the solid-state light source to the passive heat transfer structure with the intermediate dielectric heat spreader positioned between the solid-state light source and the heat exchanger, a periphery of the solid-state light source encompassed by the periphery of the intermediate dielectric heat spreader such that the intermediate dielectric heat spreader thermally conductively couples the solid-state light source to the heat exchanger and electrically isolates the heat exchanger from the solid-state light source and provides arc over protection between the solid-state light source and the heat exchanger.

15. The method of claim 14 wherein providing a heat exchanger includes providing a heat exchanger made of a filled polymer material, and wherein thermally conductively coupling an intermediate dielectric heat spreader to the heat exchanger includes thermally conductively coupling an intermediate dielectric heat spreader made of a filled polymer material.

16. The method of claim 15 wherein thermally conductively coupling an intermediate dielectric heat spreader to the heat exchanger includes overmolding the heat exchanger on at least a portion of the intermediate dielectric heat spreader.

17. The method of claim 16 wherein the heat exchanger has a cavity, and overmolding the heat exchanger on at least a portion of the intermediate dielectric heat spreader includes overmolding the heat exchanger with the intermediate dielectric heat spreader received in the cavity of the heat exchanger.

18. The method of claim 14, further comprising:

thermally coupling a primary heat spreader that is thermally conductive and electrically conductive to the intermediate dielectric heat spreader with the primary heat spreader positioned between the solid-state light source and the intermediate dielectric heat spreader, the primary heat spreader having an area greater than the area of the solid-state light source and smaller than an area of the intermediate dielectric heat spreader, and the primary heat spreader having a periphery that encompasses the area of the primary heat spreader.

19. The method of claim 18 wherein thermally coupling a primary heat spreader to the intermediate dielectric heat spreader includes thermally coupling a vapor phase heat spreader to the intermediate dielectric heat spreader, the vapor phase heat spreader having at least one channel that carries a heat exchange fluid which undergoes a phase change between a liquid and a vapor as the heat exchange fluid traverses the at least one channel between a relatively warmer portion and a relatively cooler portion of the primary heat spreader.

20. The method of claim 18 wherein thermally coupling a primary heat spreader to the intermediate dielectric heat spreader includes overmolding the intermediate dielectric heat spreader to at least a portion of the primary heat spreader.

21. The method of claim 20 wherein the intermediate dielectric heat spreader has a cavity, and overmolding the intermediate dielectric heat spreader to at least a portion of the primary heat spreader includes overmolding the intermediate dielectric heat spreader with the primary heat spreader received in the cavity of the intermediate dielectric heat spreader.