Solid state lights with thermosiphon liquid cooling structures and methods

• US 8,217,557 B2
• Filed: 08/31/2010
• Issued: 07/10/2012
• Est. Priority Date: 08/31/2010
• Status: Active Grant

• Current Assignee: Ovonyx Memory Technology, LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Sills, Scott E., de Villiers, Anton J.
• Primary Examiner(s): MACCHIAROLO, PETER J
• Application Number:
  US12/872,647
• Publication Number:
  US 20120049715A1
• Time in Patent Office: 679 Days
• Field of Search: 313484-487, 313/489, 313/498, 313/512, 313/467, 313/468, 313/499, 313501-503, 313/12, 313/35, 165/104.11, 165/104.33, 362/294, 362/272
• US Class Current: 313/12
• CPC Class Codes: F21V 29/51 using condensation or evaporation of a fluid, e.g. heat pipes
• CPC Class Codes: F21V 29/58 characterised by the coolants
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials

Abstract

A solid state lighting (SSL) device with a solid state emitter (SSE) being partially exposed in a channel loop, and methods of making and using such SSLs. The SSE can have thermally conductive projections such as fins, posts, or other structures configured to transfer heat into a fluid medium, such as a liquid coolant in the channel loop. The channel loop can include an upward channel in which the SSE is exposed to warm the coolant in the upward channel, and a downward channel through which coolant moves after being cooled by a cooling structure. The coolant in the channel loop can naturally circulate due to the heat from the SSE.

Claims

1. A solid state lighting device (SSL), comprising:

a housing having a chamber and a closed-system channel loop, the channel loop including a first channel and a second channel, wherein at least a portion of the first channel is inclined at an angle relative to horizontal, and wherein the channel loop includes a cooling structure between the first channel and the second channel;

a coolant fluid in the closed-system channel loop, wherein the cooling structure is configured to transfer heat from the coolant fluid; and

a solid state emitter (SSE) carried by the housing, the SSE having an active portion from which light is emitted and a back portion, the active portion facing toward the chamber, and one of the active portion and the back portion directly contacting the coolant fluid in the first channel.

2. The SSL device of claim 1 wherein the coolant fluid comprises a dielectric fluid that expands when heated such that the dielectric fluid in the first channel rises and the dielectric fluid circulates from the first channel to the cooling structure.

3. The SSL device of claim 1, wherein:

the housing has a base and a side section along at least a portion of the base that together define the chamber;

the side section further comprises an inner wall and a first intermediate wall that together define the first channel;

the side section further comprises an outer wall and a second intermediate wall that together define the second channel;

the first channel and second channel are in fluid communication with each other and thereby form a recirculating fluid current loop having a hot portion in the first channel and a cold portion in the second channel;

the cooling structure is between the hot portion and the cold portion;

the SSE is attached to the side section such that the active portion is exposed to the channel;

the coolant comprises a transparent coolant;

the SSL device further comprises a reflector in the chamber that has a reflective surface the directs light from the active portion of the SSE along a primary light direction; and

the SSL device further comprises a lens over the chamber; and

the chamber, the lens, the cooling structure, and the side section form an enclosure that contains the coolant within the SSL device.

4. The SSL device of claim 1 wherein heat from the SSEs is sufficient to cause a first phase change in the coolant and the cooling structure is configured to cause a second phase change in the coolant.

5. The SSL device of claim 1 wherein the cooling structure includes at least one of internal fins contacting the coolant and external fins exposed outside the SSL device.

6. The SSL device of claim 1 wherein the coolant comprises liquid coolant.

7. The SSL device of claim 1, wherein:

the housing has a base and a side section along at least a portion of the base that together define the chamber;

the side section further comprises an inner wall and a first intermediate wall that together define the first channel;

the side section further comprises an outer wall and a second intermediate wall that together define the second channel;

the first channel and second channel are in fluid communication with each other and thereby form a fluid current loop having a hot portion in the first channel and a cold portion in the second channel;

the SSE is attached to the side section such that the back portion is exposed to the first channel;

the back portion of the SSE comprises a plurality of projections in the first channel;

the chamber is separated from the first and second channels by the inner wall;

the SSL device further comprises a reflector in the chamber that has a reflective surface the directs light from the active portion of the SSE along a primary light direction; and

the first channel, the second channel, and the cooling structure form an enclosure containing the coolant.

8. The SSL device of claim 7, wherein the back portion further comprises a first electrically conductive projection and a second electrically conductive projection extending from the active portion of the SSE.

9. The SSL device of claim 7 wherein the first channel has an inlet and an outlet, the first channel having a first width near the inlet and a second width near the outlet, and wherein the first width is smaller than the second width.

10. The SSL device of claim 7 wherein the chamber is open to an external environment.

11. The SSL device of claim 1, further comprising an access port through which the coolant fluid can be added or changed.

31. The SSL device of claim 1 wherein the cooling structure includes at least one fin that directly contacts the coolant fluid located in the housing.

12. A solid state lighting device (SSL), comprising:

a housing having a channel loop configured to recirculate a fluid within the SSL device, the channel loop including—

an upward channel having an upward inlet and an upward outlet,

a downward channel having a downward inlet and a downward outlet,

an upward return between the upward outlet and the downward inlet, and

a downward return between the downward outlet and the upward inlet;

a dielectric coolant fluid in the channel loop;

a cooling structure in the upward return; and

a solid state emitter (SSE) carried by the housing with at least a portion of the SSE in the upward channel, the upward channel being oriented such that the dielectric coolant fluid in the upward channel directly contacts and is heated by the SSE and rises such that a fluid current is induced in the channel loop upward through the upward channel and downward through the downward channel to cool the portion of the SSE.

13. The SSL device of claim 12 wherein the SSE includes a back portion having a plurality of thermally conductive projections extending into the upward channel.

14. The SSL device of claim 12 wherein the cooling structure comprises at least one of internal cooling fins contacting the coolant in the upward return and external cooling fins exposed outside the SSL device.

15. The SSL device of claim 12, further comprising a reflector in an optical path of the SSE, wherein light from the SSE is reflected from the reflector and out of the SSL device.

16. The SSL device of claim 12 wherein the SSE has a light-emitting active portion, and wherein the light-emitting active portion is exposed in the upward channel.

17. The SSL device of claim 16 wherein the coolant fluid comprises a transparent fluid.

18. The SSL device of claim 16 wherein the coolant fluid contains a converter material blended with the coolant fluid.

19. The SSL device of claim 12, the housing further comprising a chamber separate from the channel loop.

20. The SSL device of claim 12 wherein the upward channel includes a Joule-Thompson expansion having a first width in the upward channel near the upward inlet and a second width, larger than the first width, in the upward channel near the upward outlet.

21. The SSL device of claim 12 wherein—

the SSL device further comprises a reflective cone in an optical path of the SSEs and configured to direct light from the SSEs in a primary lighting direction;

a surface of the reflective base is angled relative to the primary lighting direction by a first angle, phi;

a lighting surface of the SSE is angled relative to the primary lighting direction by a second angle, theta;

the surface of the reflective base and the lighting surface are angled relative to one another by a third angle, alpha; and

the first angle, phi, is at least approximately equal to the third angle, alpha, plus the second angle, theta.

22. The SSL device of claim 12 wherein the SSE is oriented to emit light generally horizontally, and wherein the upward and downward channels are oriented generally vertically.

23. The SSL device of claim 12 wherein the SSE comprises a plurality of thermally and electrically conductive projections exposed to the upward channel, wherein the projections comprise a first electrical contact and a second electrical contact, wherein the first and second electrical contacts are electrically isolated from one another, and wherein the first electrical contact is connected to an N contact on the SSE and the second electrical contact is connected to a P contact on the SSE.

24. A method of manufacturing a solid state lighting (SSL) device, comprising:

forming a support with a recirculating closed-system channel loop through the support;

flowing a coolant fluid into the closed-system channel loop and sealing the coolant fluid in the closed-system channel loop; and

attaching a solid state emitter (SSE) to the support such that at least a portion of the SSE directly contacts coolant fluid in a first portion of the recirculating closed-system channel loop, wherein the first portion of the closed-system channel loop is oriented generally vertically.

25. The method of claim 24, further comprising positioning a reflective surface in an optical path of the SSE, wherein the reflective surface is oriented relative to the SSEs to receive light emitted from the SSE and to reflect the light out of the SSL device through at least a portion of the coolant fluid and through the lens.

26. The method of claim 24, further comprising:

operating the SSE such that heat is produced by the SSE and transferred to the coolant fluid; and

passively circulating the coolant fluid through the recirculating closed-system channel loop using the heat produced by the SSE.

27. The method of claim 24 wherein forming the support comprises forming an enclosed chamber in fluid communication with the recirculating closed-system channel loop.

28. The method of claim 24 wherein forming the support comprises forming a chamber separate from the closed-system channel loop.

29. The method of claim 28 wherein the chamber is filled with a material different than the liquid coolant.

30. The method of claim 24, further comprising forming at least one fin that directly contacts the coolant fluid to transfer heat from the coolant fluid.

32. A solid state lighting device (SSL), comprising:

a housing having a fluid chamber, the fluid chamber including a channel loop having a plurality of channels;

coolant fluid in the fluid chamber;

a cooling structure configured to transfer thermal energy from the coolant fluid, the cooling structure including at least one heat transfer fin that directly contacts the coolant fluid in the fluid chamber; and

a solid state emitter (SSE) coupled to the housing, the SSE including an active portion from which light is emitted and a back portion, and at least one of the active portion and the back portion directly contacting the cooling fluid.

33. The SSL device of claim 32 wherein at least one of the active portion and the back portion directly contacts the coolant fluid in one of the channels.

34. The SSL device of claim 32 wherein the coolant fluid comprises a dielectric fluid.