Thermally protected LED array

• US 5,785,418 A
• Filed: 10/20/1997
• Issued: 07/28/1998
• Est. Priority Date: 06/27/1996
• Status: Expired due to Term

• Current Assignee: Denny Foy, Relume Technologies, Inc. (Revolution Lighting Technologies, Inc.)
• Original Assignee: Relume Corporation
• Inventors: Hochstein, Peter A.
• Primary Examiner(s): Sember, Thomas M.
• Application Number:
  US08/953,924
• Time in Patent Office: 281 Days
• Field of Search: 362/227, 362/234, 362/235, 362/247, 362/294, 362/373, 362/800
• US Class Current: 362/373
• CPC Class Codes: B60Q 1/2696 Mounting of devices using LEDs
• CPC Class Codes: B61L 2207/02 using light-emitting diodes [LEDs]
• CPC Class Codes: B61L 5/1854 Mounting and focussing of the light source in a lamp, fixing means
• CPC Class Codes: F21S 43/14 Light emitting diodes [LED]
• CPC Class Codes: F21S 45/37 specially adapted for signal lamps
• CPC Class Codes: F21S 45/48 with means for conducting heat from the inside to the outside of the lighting devices, e.g. with fins on the outer surface of the lighting device
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: F21V 29/74 with fins or blades
• CPC Class Codes: F21V 29/83 the elements having apertures, ducts or channels, e.g. heat radiation holes
• CPC Class Codes: F21V 29/89 Metals
• CPC Class Codes: F21W 2111/02 for roads, paths or the like
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G08G 1/095 Traffic lights
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements
• CPC Class Codes: H05K 1/0206 by printed thermal vias
• CPC Class Codes: H05K 2201/0209 Inorganic, non-metallic particles
• CPC Class Codes: H05K 2201/09781 Dummy conductors, i.e. not used for normal transport of current; Dummy electrodes of components
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 3/0061 onto a metallic substrate, e.g. a heat sink heat sinks for electric apparatus H05K7/20
• CPC Class Codes: H05K 3/42 Plated through-holes or plated via connections
• CPC Class Codes: Y10S 362/80 : Light emitting diode

Abstract

An electrically driven L.E.D. lamp assembly (14) comprising an electrically insulating circuit board (26) having opposed first and second surfaces with light emitting diodes (28) having positive and negative leads (30, 32) mounted on the first surface. A plurality of pads (50) of thermally conductive plating are disposed on the second side with each pad (50) associated with the leads to conduct heat from each of the leads to one of the pads (50). A heat sink includes a base (36) overlying the second surface and layers (56, 58) of thermally conductive and electrically non-conductive material are disposed between the conductive plating and the heat sink (36) to secure the conductive plating and the circuit board (26) to the heat sink (36) while preventing a short between the conductive plating (50) and the heat sink (36). The assembly is characterized by a thermally insulating material (44) disposed over the heat sink (36) for sandwiching the heat sink against the conductive plating (50) to limit heat transfer into the heat sink from the outside.

Claims

1. An electrically driven L.E.D. lamp assembly comprising;

a heat sink having first and second faces,

an array of light emitting diodes disposed over said first face of said heat sink,

each of said light emitting diodes having positive and negative leads,

an electrically conductive circuit interconnecting said leads,

electrically insulating means for electrically insulating said conductive circuit and said light emitting diodes from said first face of said heat sink,

said assembly characterized by a thermally insulating material disposed over said second face of said heat sink for limiting heat transfer to said heat sink from sources other than said light emitting diodes.

2. An assembly as set forth in claim 1 including a heat shield surrounding said thermally insulating material.

3. An assembly as set forth in claim 1 wherein said heat sink includes a heat dissipator portion extending away from said insulating material to convey heat from said conductive plating.

4. An assembly as set forth in claim 3 including a housing supporting said heat sink.

5. An assembly as set forth in claim 4 wherein said housing defines a space around said heat shield.

6. An assembly as set forth in claim 5 including a gasket supporting said heat sink in said housing.

7. An assembly as set forth in claim 6 wherein said housing comprises a traffic light housing presenting a light emitting opening and a sun hood extending from said opening, said heat dissipator portion comprising a shell extending forwardly of said light emitting diodes, said shell extending from said opening within and spaced from said sun hood.

8. An assembly as set forth in claim 7 wherein said shell includes perforations therein for radiating heat.

9. An assembly as set forth in claim 8 including an electrically insulating circuit board having opposed first and second surfaces, said light emitting diodes mounted on said first surface, a thermally conductive plating on said second surface, said conductive plating being thermally connected to said leads to conduct heat from said leads to said conductive plating, said first face of said heat sink overlying said conductive plating, said electrically insulating means comprising a thermally conductive layer disposed between said conductive plating and said first face of said heat sink to secure said conductive plating and said board to said first face of said heat sink, said conductive plating comprising a plurality of pads disposed on said second surface of said circuit board, said thermally conductive material comprising an adhesive layer of electrically insulating adhesive disposed between said pads and said first face of said heat sink, and a second electrically insulating material for preventing the adhesive from being thin enough to cause electrical shorting.

10. An assembly as set forth in claim 8 wherein said electrically insulating means comprises a coating disposed over said first face of said heat sink, said electrically conductive circuit disposed on said coating, and an electrically conductive adhesive connecting said leads to said circuit.

11. An assembly as set forth in claim 8 wherein said electrically insulating means comprises a coating disposed over said first face of said heat sink, a metal substrate disposed over said coating, a thermally conductive and electrically insulating layer on said substrate, said electrically conductive circuit disposed on said insulating layer, and an electrically conductive adhesive connecting said leads to said circuit.