LED-BASED LIGHTING FIXTURES FOR SURFACE ILLUMINATION WITH IMPROVED HEAT DISSIPATION AND MANUFACTURABILITY

• US 20080278941A1
• Filed: 05/02/2008
• Published: 11/13/2008
• Est. Priority Date: 05/07/2007
• Status: Active Grant

• Current Assignee: Philips Lighting BV (Koninklijke Philips N.V.)
• Original Assignee: Philips Solid-State Lighting Solutions (Koninklijke Philips N.V.)
• Inventors: Piepgras, Colin, Logan, Derek
• Granted Patent: US 7,878,683 B2
• Time in Patent Office: Days
• US Class Current: 362/234
• CPC Class Codes: F21S 4/28 rigid, e.g. LED bars
• CPC Class Codes: F21S 8/036 by means of a rigid support, e.g. bracket or arm
• CPC Class Codes: F21V 15/01 Housings, e.g. material or assembling of housing parts F21V15/02 takes precedence housings forming signs or letters G09F13/04
• CPC Class Codes: F21V 15/013 the housing being an extrusion
• CPC Class Codes: F21V 15/04 Resilient mountings, e.g. shock absorbers shock absorbing devices of vehicle headlamp housings B60Q1/0491; in general F16F15/04
• CPC Class Codes: F21V 17/12 by screwing
• CPC Class Codes: F21V 21/005 for several lighting devices in an end-to-end arrangement, i.e. light tracks
• CPC Class Codes: F21V 29/507 of means for protecting lighting devices from damage, e.g. housings
• CPC Class Codes: F21V 3/02 characterised by the shape
• CPC Class Codes: F21V 5/00 Refractors for light sources characterised by cooling arrangements F21V29/504
• CPC Class Codes: F21V 5/002 using microoptical elements for redirecting or diffusing light
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21Y 2103/10 comprising a linear array of point-like light-generating elements
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H05B 45/355 Power factor correction [PFC]; Reactive power compensation
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

LED-based lighting apparatus and assembly methods in which mechanical and/or thermal coupling between respective components is accomplished via a transfer of force from one component to another. In one example, a multiple-LED assembly is disposed in thermal communication with a heat sink that forms part of a housing. A primary optical element situated within a pressure-transfer member is disposed above and optically aligned with each LED. A shared secondary optical facility forming another part of the housing is disposed above and compressively coupled to the pressure-transfer members. A force exerted by the second optical facility is transferred via the pressure-transfer members so as to press the LED assembly toward the heat sink, thereby facilitating heat transfer. In one aspect, the LED assembly is secured in the housing without the need for adhesives. In another aspect, the secondary optical facility does not directly exert pressure onto any primary optical element, thereby reducing optical misalignment.

Claims

1. A lighting apparatus, comprising:

a heat sink having a first surface;

an LED printed circuit board having second and third opposing surfaces, wherein the second surface is disposed on the first surface of the heat sink and wherein the third surface has at least one LED light source disposed thereon;

an integrated lens-housing member having a transparent upper wall disposed to receive light emitted by the at least one LED light source;

a pressure-transfer member having a support structure extending generally in the direction from the LED printed circuit board to the transparent upper wall of the integrated lens-housing member and further having a pressure-transfer surface connected to the support structure, wherein the support structure defines an aperture, and wherein the pressure-transfer surface is disposed on the third surface of said LED printed circuit board and further disposed proximate to the LED light source; and

an optic member disposed in the aperture defined by the support structure of the pressure-transfer member,

wherein the integrated lens-housing member is compressively coupled to the pressure-transfer member, such that a force exerted by the integrated lens-housing member is transferred via the pressure-transfer member to the pressure-transfer surface so as to press the LED printed circuit board toward the first surface of the heat sink, so as to provide for heat transfer from the LED printed circuit board to the heat sink.

2. The lighting apparatus of claim 1, wherein the integrated lens-housing member has opposing side walls contiguous with the transparent upper wall, and wherein the opposing side walls are connected to the heat sink so as to generate the force exerted by the integrated lens-housing member onto the pressure-transfer member.

3. The lighting apparatus of claim 1, wherein the integrated lens-housing member is connected to the heat sink by a non-adhesive connector.

4. The lighting apparatus of claim 1, wherein the integrated lens-housing member is not compressively coupled to the optic member.

5. The lighting apparatus of claim 1, further comprising a compliant member interposed between the integrated lens-housing member and the support structure of the pressure-transfer member.

6. The lighting apparatus of claim 5, wherein the compliant member comprises a thermoplastic elastomer.

7. The lighting apparatus of claim 1, wherein the transparent upper wall of the integrated lens-housing member has an inner surface having at least one connecting pin, and further comprising a light diffusion layer disposed on the inner surface of the transparent upper wall, the connecting pin being configured to hold the light diffusion layer against the inner surface of the transparent upper wall.

8. The lighting apparatus of claim 1, further comprising a thermal interface layer interposed between the LED printed circuit board and the first surface of the heat sink.

9. The lighting apparatus of claim 8, wherein the thermal interface layer comprises graphite.

10. The lighting apparatus of claim 1, wherein the integrated lens-housing member further has opposing end walls contiguous with the transparent upper wall.

11. The lighting apparatus of claim 1, wherein the integrated lens-housing member comprises a plastic.

12. The lighting apparatus of claim 11, wherein the integrated lens-housing member comprises a polycarbonate.

13. The lighting apparatus of claim 1, wherein the integrated lens-housing member consists essentially of a plastic.

14. The lighting apparatus of claim 13, wherein the integrated lens-housing member consists essentially of a polycarbonate.

15. The lighting apparatus of claim 1, wherein a shortest distance between the pressure-transfer surface and the LED light source is less than about 2 millimeters.

16. The lighting apparatus of claim 15, wherein the shortest distance between the pressure-transfer surface and the LED light source is about 1 millimeter.

17. The lighting apparatus of claim 1, where a minimum thickness of the integrated lens-housing member is about 3 millimeters.

18. The lighting apparatus of claim 1, wherein the pressure-transfer member is opaque.

19. The lighting apparatus of claim 1, wherein the integrated lens-housing member further comprises first and second opposing over-molded end walls contiguous with the opposing side walls and the transparent upper wall.

20. A linear lighting apparatus comprising a first and second lighting apparatus as claimed in claim 19, wherein the first over-molded end cap of the first lighting apparatus opposes the second over-molded end cap of the second lighting apparatus.

21. The linear lighting apparatus of claim 20, wherein a distance between the first over-molded end cap of the first lighting apparatus and the second over-molded end cap of the second lighting apparatus is less than about 3 millimeters, thereby defining a gap between the first and second lighting apparatus.

22. The linear lighting apparatus of claim 1, wherein the optic member comprises a TIR optic.

23. An LED-based lighting apparatus, comprising:

a heat sink;

an LED assembly including a plurality of LEDs disposed on a substrate;

a plurality of optical units, each optical unit of the plurality of optical units comprising a primary optical element situated within a pressure-transfer member, each optical unit disposed above a different LED of the plurality of LEDs; and

a secondary optical facility disposed above and compressively coupled to the plurality of optical units, such that a force exerted by the second optical facility is transferred via the pressure-transfer members so as to press the LED assembly toward the heat sink to facilitate heat transfer from the LED assembly to the heat sink.

24. The apparatus of claim 23, wherein:

the heat sink forms a first portion of a housing for the LED assembly; and

the secondary optical facility forms a second portion of a housing for the LED assembly.

25. The apparatus of claim 24, wherein the LED assembly is secured in the housing without an adhesive.

26. The apparatus of claim 23, wherein the secondary optical facility does not directly exert the force onto any primary optical element.

27. A method of assembling an LED-based lighting apparatus comprising a heat sink, an LED assembly including a plurality of LEDs disposed on a substrate, and a plurality of optical units the method comprising steps of:

(a) disposing the LED assembly over the heat sink;

(b) retaining the plurality of optical units over the LED assembly such that each optical unit is disposed over a different LED of the plurality of LEDs; and

(c) securing the LED assembly and the primary optical elements against the heat sink without employing adhesive materials.

28. The method of claim 27, wherein the step (c) comprises compressively coupling a a secondary optical facility the plurality of optional units, such that a force exerted by the second optical facility secures the LED assembly against the heat sink.