Light-emitting diode reflector assembly having a heat pipe

• US 6,976,769 B2
• Filed: 06/11/2003
• Issued: 12/20/2005
• Est. Priority Date: 06/11/2003
• Status: Expired due to Fees

• Current Assignee: Ticona Polymers, Inc. (Celanese Corporation)
• Original Assignee: Cool Options, Inc.
• Inventors: Sagal, E. Mikhail, Miller, James, McCullough, Kevin
• Primary Examiner(s): Husar, Stephen
• Assistant Examiner(s): Sawhney, Hargobind S.
• Application Number:
  US10/459,234
• Publication Number:
  US 20040252502A1
• Time in Patent Office: 923 Days
• Field of Search: 362/26, 362/27, 362/97, 362/218, 362/238, 362/240, 362/241, 362/294, 362/341, 362/345, 362/373, 362/555, 362/580, 362/516, 362/519, 362547-549, 362/545, 362/800, 362/541
• US Class Current: 362/345
• CPC Class Codes: B29C 45/006 Joining parts moulded in separate cavities
• CPC Class Codes: B29C 45/14598 Coating tubular articles
• CPC Class Codes: B29L 2031/747 Lightning equipment
• CPC Class Codes: F21S 41/37 characterised by their material, surface treatment or coatings
• CPC Class Codes: F21S 45/47 Passive cooling, e.g. using fins, thermal conductive elements or openings
• 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 29/505 of reflectors
• CPC Class Codes: F21V 29/51 using condensation or evaporation of a fluid, e.g. heat pipes
• CPC Class Codes: F21V 7/0008 providing for indirect lighting
• CPC Class Codes: F21V 7/24 characterised by the material
• CPC Class Codes: F21V 7/28 characterised by coatings
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: F28D 15/02 in which the medium condenses and evaporates, e.g. heat pipes heat pipes used in solar heat collectors F24S10/95; in radiators F28D1/0226; in nuclear reactors G21C15/257
• CPC Class Codes: H05K 1/0203 Cooling of mounted components H05K1/0272 takes precedence
• CPC Class Codes: H05K 1/0209 External configuration of printed circuit board adapted for heat dissipation, e.g. lay-out of conductors, coatings
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]

Abstract

A light-emitting diode reflector assembly having a heat pipe and a reflector body is provided. The assembly further includes a mounting member for mounting a circuit board having an array of light-emitting diodes. The mounting member and reflector body are made from a thermally-conductive polymer composition comprising: i) about 20% to about 80% by weight of a base polymer matrix such as polycarbonate; and ii) about 20% to about 80% by weight of a thermally-conductive material such as carbon graphite.

Claims

1. An injection molded light-emitting diode reflector assembly formed from polymer materials, comprising:

a reflector body having a recessed portion with a light-reflecting surface and a peripheral sidewall surrounding said recessed portion, said reflector body comprising a first thermally-conductive polymer composition;

a circuit board-mounting member extending across said reflector body between two spaced apart points on said side wall in spaced relation to said light reflecting surface, said mounting member including

an elongated heat sink component having an upper and lower outer surface, said component comprising a second thermally-conductive polymer composition; and

a heat pipe embedded in the heat sink component; and

a circuit board mounted to the lower surface of the mounting member, said circuit board having an array of light-emitting diodes mounted thereon that direct light beams onto the light-reflecting surface of the reflector body.

2. The reflector assembly of claim 1, wherein the first and second thermally-conductive polymer compositions are the same.

3. The reflector assembly of claim 1, wherein said first and second thermally conductive polymer compositions comprise:

a) about 20% to about 80% by weight of a base polymer matrix; and

b) about 20% to about 80% by weight of a thermally-conductive filler material.

4. The reflector assembly of claim 3, wherein the polymer matrix comprises a thermoplastic polymer.

5. The reflector assembly of claim 4, wherein the thermoplastic polymer is selected from the group consisting of polycarbonates, polyethylene, polypropylene, acrylics, vinyls, fluorocarbons, polyamides, polyphenylene sulfide, and liquid crystal polymers.

6. The reflector assembly of claim 3, wherein the polymer matrix comprises a thermosetting polymer.

7. The reflector assembly of claim 6, wherein the thermosetting polymer is selected from the group consisting of elastomers, epoxies, polyesters, polyimides, and acrylonitriles.

8. The reflector assembly of claim 3, wherein the thermally-conductive filler material is a metal, metal oxide, ceramic, or carbon material.

9. The reflector assembly of claim 8, wherein the thermally-conductive filler material is selected from the group consisting of aluminum, copper, magnesium, brass, alumina, magnesium oxide, silicon nitride, boron nitride, carbon black, and carbon graphite.

10. The reflector assembly of claim 3, wherein the polymer composition further comprises about 5 to about 30% by weight of a reinforcing material.

11. The reflector assembly of claim 10, wherein the reinforcing material is glass.

12. The reflector assembly of claim 3, wherein the polymer composition further comprises an additive selected from the group consisting of antioxidants, plasticizers, stabilizers, dispersing agents, coloring agents, and mold-releasing agents.

13. The reflector assembly of claim 3, wherein the polymer composition comprises about 74% by weight of polycarbonate, about 24% by weight of carbon graphite, and about 1% by weight of a mold-releasing agent.

14. The reflector assembly of claim 1, wherein the reflector body has a thermal conductivity of greater than 10 W/m°

K.

15. A method for making an injection molded light-emitting diode reflector assembly, comprising the steps of:

providing a first molten polymer composition, said composition formed from about 20% to about 80% by weight of a base polymer matrix and about 20% to about 80% by weight of a thermally-conductive filler material;

injecting the first molten polymer composition into a mold to form a thermally-conductive reflector body having a recessed portion with a light-reflecting surface and a peripheral side wall surrounding said recessed portion;

providing a second molten polymer composition, said composition formed from about 20% to about 80% by weight of a base polymer matrix and about 20% to about 80% by weight of a thermally-conductive filler material;

injecting the second molten polymer composition into a mold having an inserted heat pipe to form a circuit board-mounting member comprising an elongated heat sink component having an upper and lower outer surface, and embedded heat pipe;

mounting a circuit board having an array of light-emitting diodes mounted thereon to the lower surface of the mounting member; and

connecting the mounting member to the reflector body, said mounting member extending across said reflector body between two spaced apart points on said side wall in spaced relation to said light reflecting surface, thereby forming a light-emitting diode reflector assembly.

16. The method of claim 15, wherein the first and second thermally-conductive polymer compositions are the same.

17. The method of claim 16, wherein the polymer matrix comprises a thermoplastic polymer.

18. The method of claim 16, wherein the polymer matrix comprises a thermosetting polymer.

19. The method of claim 16, wherein the thermally-conductive filler material is a metal, metal oxide, ceramic, or carbon material.

20. The method of claim 19, wherein the thermally-conductive filler material is selected from the group consisting of aluminum, copper, magnesium, brass, alumina, magnesium oxide, silicon nitride, boron nitride, carbon black, and carbon graphite.

21. The method of claim 16, wherein the polymer composition further comprises about 5 to about 30% by weight of a reinforcing material.

22. The method of claim 16, wherein the polymer composition further comprises an additive selected from the group consisting of antioxidants, plasticizers, stabilizers, dispersing agents, coloring agents, and mold-releasing agents.

23. The method of claim 16, wherein the polymer composition comprises about 74% by weight of polycarbonate, about 24% by weight of carbon graphite, and about 1% by weight of a mold-releasing agent.