Thermal management system for LED array

• US 7,819,556 B2
• Filed: 02/26/2008
• Issued: 10/26/2010
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Nuventix, Inc. (LTI Flexible Products Inc.)
• Original Assignee: Nuventix, Inc. (LTI Flexible Products Inc.)
• Inventors: Darbin, Stephen, Heffington, Samuel N., Mahalingam, Raghavendran, Jones, Lee M.
• Primary Examiner(s): Alavi; Ali
• Application Number:
  US12/072,610
• Publication Number:
  US 20080219007A1
• Time in Patent Office: 973 Days
• Field of Search: 362/294, 362/373, 362/547, 362/101, 257/715, 361/700, 361701-703, 165/104.21, 165/104.33, 165/80.4
• 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: H01L 23/427 Cooling by change of state, e.g. use of heat pipes by liquefied gas H01L23/445
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/648 the elements comprising fluids, e.g. heat-pipes
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

A device, comprising (a) a chamber having a liquid disposed therein, (b) an LED array having a first surface which is in contact with said liquid, and (c) at last one actuator adapted to dislodge vapor bubbles from said first surface through the emission of pressure vibrations.

Claims

1. A device, comprising:

a chamber having a liquid disposed therein;

an LED array having a first surface which is in contact with said liquid; and

at least one actuator adapted to dislodge vapor bubbles from said first surface through the emission of pressure vibrations.

2. The device of claim 1, wherein said first surface is a light emitting surface of the LED array.

3. The device of claim 1, wherein said LED array is disposed on a first wall of said chamber.

4. The device of claim 3, wherein said at least one actuator is an actuator array, and wherein said actuator array is disposed on a second wall of said chamber.

5. The device of claim 1, wherein said at least one actuator is an actuator array, and wherein said LED array and said actuator array are interdispersed.

6. The device of claim 1, wherein said at least one actuator is an ultrasonic actuator, and wherein said pressure vibrations comprise ultrasonic acoustic/pressure waves.

7. The device of claim 1, wherein said at least one actuator comprises:

a diaphragm;

a piezoelectric element attached to said diaphragm; and

a circuit for driving said piezoelectric element, said driving circuit comprising a sinusoidal function generator and an amplification chip.

8. The device of claim 1, wherein said chamber further comprises:

an inflow pipe at a first wall of said chamber, said inflow pipe being in fluidic communication with an interior of said chamber;

an outflow pipe at a second wall of said chamber, said outflow pipe being in fluidic communication with an interior of said chamber;

wherein said liquid in said chamber exits said chamber through said outflow pipe and enters said chamber through said inflow pipe; and

a reservoir in fluid communication with said chamber via said inflow pipe and said outflow pipe, said reservoir containing said liquid.

9. The device of claim 1, wherein said chamber contains a heat sink material, and wherein said LED array is disposed adjacent to said heat sink material.

10. The device of claim 1, wherein said device further comprises a window that is essentially transparent to wavelengths of visible light emitted by the LED array, and wherein said window forms a wall of said chamber.

11. The device of claim 10, wherein said window is disposed in opposing relation to said LED array.

12. The device of claim 10, wherein the interior of said chamber is further equipped with at least one reflective surface.

13. The device of claim 1, wherein said liquid comprises a fluorinated ether of the formula

R—

O—

R_f

wherein R_f is a perfluorinated alkyl, aryl, or alkylaryl group, and wherein R is a nonfluorinated alkyl, aryl, or alkylaryl group.

14. The device of claim 13, wherein R_f and R are alkyl groups.

15. The device of claim 13, wherein the fluorinated ether is selected from the group consisting of C₃F₇OCH₃, C₄F₉OCH₃, and C₄F₉OC₂H₅.

16. The device of claim 1, wherein said at least one actuator comprises an actuator array, and wherein said actuator array is adapted such that the acoustic/pressure vibrations produced by the actuator array induce the formation of a plurality of synthetic jets which impinge on said first surface.

21. The device of claim 15, wherein said device further comprises a window that is essentially transparent to wavelengths of visible light emitted by the LED array.

22. The device of claim 15, wherein said chamber is partially filled with said liquid.

17. A device, comprising:

a chamber having a liquid disposed therein;

an LED array; and

an actuator array adapted to cool said LED array by atomizing said liquid.

18. The device of claim 17, wherein said actuator comprises an ultrasonic actuator, and wherein said pressure vibrations comprise ultrasonic acoustic/pressure waves.

19. The device of claim 17, wherein said actuator comprises:

a diaphragm;

a piezoelectric element attached to said diaphragm; and

a circuit for driving said piezoelectric element, said driving circuit comprising a sinusoidal function generator and an amplification chip.

20. The device of claim 17, wherein said device is equipped with a plurality of fins disposed outside of said chamber, and wherein said plurality of fins are in thermal contact with the interior of said chamber.

23. The device of claim 17, wherein said LED array is disposed on a first wall of said chamber, and wherein said actuator array is disposed on a second wall of said chamber.

24. The device of claim 17, wherein said LED array and said actuator array are interdispersed.

25. A device, comprising:

a chamber having a liquid disposed therein;

a plurality of LEDs, wherein each of said plurality of LEDs has a light-emitting surface which is in physical contact with said liquid; and

at least one actuator adapted to dislodge vapor bubbles from the light-emitting surfaces of said LEDs through the emission of acoustic/pressure vibrations which induce the formation of a plurality of synthetic jets which impinge on said first surface.

26. A device, comprising:

an LED array having a light emitting surface;

an actuator array; and

a window, disposed in opposing relation to said light emitting surface;

wherein said light emitting surface, said actuator array, and said window define a portion of a chamber having a liquid disposed therein, and wherein said actuator array is adapted to atomize said liquid.

27. The device of claim 26, wherein the exterior of said chamber is equipped with a plurality of fins which are in thermal contact with the interior of said chamber, and wherein said device is equipped with a synthetic jet ejector adapted to emit a plurality of synthetic jets across the surfaces of said plurality of fins.