Heat dissipating L.E.D. traffic light

• US 5,782,555 A
• Filed: 06/27/1996
• Issued: 07/21/1998
• Est. Priority Date: 06/27/1996
• Status: Expired due to Term

• Current Assignee: Relume Technologies, Inc. (Revolution Lighting Technologies, Inc.)
• Original Assignee: Relume Corporation
• Inventors: Hochstein, Peter A.
• Primary Examiner(s): Quach, Y My
• Application Number:
  US08/671,249
• Time in Patent Office: 754 Days
• Field of Search: 362/227, 362/234, 362/235, 362/249, 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: 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 2111/00 Use or application of lighting devices or systems for signalling, marking or indicating, not provided for in codes F21W2102/00 – F21W2107/00
• 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 1/056 the metal substrate being covered by an organic insulating layer
• 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 and an electrically conductive plating on the first surface for establishing discrete and electrically conductive paths (34) for electrically interconnecting the positive lead (30) of one the light emitting diodes to the negative lead (32) of another of the light emitting diodes. A plurality of holes extend through the board (26) and a plurality of pads (50) of thermally conductive plating are disposed on the second side with each pad (50) associated with one of the holes and a thermally conductive material extending through the holes and thermally connecting each of the pads (50) and one of the leads to conduct heat from each of the leads to one of the pads (50) while maintaining electrical isolation between the pads. The pads (50) are rectangular in area configuration and are separated by a grid of crossing lines (54) of separation, the lines (54) being in transverse groups with all the lines (54) in one group being parallel and at right angles to the lines (54) in the other group and are separated from one another a discrete distance which is only of a magnitude sufficient to prevent electrical conductivity from pad (50) to pad (50). A heat sink includes a base (36) overlying the second surface and a shell (38) extending forwardly from the base (36) in front of the light emitting diodes (28) for conducting heat to the light emitting side of the assembly.

Claims

1. An electrically driven L.E.D. lamp assembly (14) comprising:

an electrically insulating circuit board (26) having opposed first and second surfaces,

light emitting diodes (28) mounted on said first surface,

each of said light emitting diodes (28) having positive and negative leads (30,

     32),

an electrically conductive plating on said first surface for establishing discrete and electrically conductive paths (34) for electrically interconnecting said positive lead (30) of one of said light emitting diodes (28) to said negative lead (32) of another of said light emitting diodes (28),

a plurality of first holes through said board (26),

a plurality of pads (50) of thermally conductive plating on said second surface with each pad associated with one of said holes,

said pads (50) extending laterally from said holes and being separated from one another a discrete distance (54) which is only of a magnitude sufficient to prevent electrical conductivity from pad to pad, said pads (50) being multi-sided and said discrete distance (54) being defined by a grid of thin lines separating said pads (50), said pads (50) occupying over eighty percent of an area over which said grid lines extend,

a thermally conductive first material extending through said holes and thermally connecting each of said pads (50) and one of said leads (30,

     32) to conduct heat from each of said leads (30,

     32) to one of said pads (50) while maintaining electrical isolation between said pads (50),

a heat sink (36, 36(a)) overlying said pads (50), and

a thin layer (58) of electrically insulating and thermally conductive second material disposed between said pads (50) and said heat sink (36, 36(a)) to prevent electrical shorting between said pads (50) by said heat sink (36, 36(a)) while maximizing heat transfer to said heat sink (36, 36(a).

2. An assembly as set forth in claim 1 including a plurality of lead holes extending through said board (26) with said first material extending through each of said lead holes to provide thermal conductivity from each lead hole to one of said pads (50), said first holes (52) being dispersed among said lead holes.

3. An assembly as set forth in claim 1 wherein said heat sink includes a base (36) overlying said pads (50) and a shell (38) extending forwardly from said base (36) in front of said light emitting diodes (28) for conducting heat forwardly of said first surface of said circuit board (26).

4. An assembly as set forth in claim 3 including a casing (42) surrounding said base (34) of said heat sink, insulating material (44) disposed between said base (34) and said casing (42) to limit heat transfer to said heat sink from outside said casing (42).

5. An assembly as set forth in claim 4 including a traffic light housing (10) presenting a light opening and a sun hood (24) extending from said opening, said casing (42) mounted in said opening with said shell (38) extending forwardly within and spaced from said sun hood (24).

6. An assembly as set forth in claim 4 wherein said shell (38) includes perforations (40) therein for radiating heat.

7. An electrically driven L.E.D. lamp assembly comprising:

an electrically insulating circuit board (26) having opposed first and second surfaces,

light emitting diodes (28) mounted on said first surface,

each of said light emitting diodes (28) having positive and negative leads (30,

     32),

an electrically conductive plating on said circuit board (26) for establishing discrete and electrically conductive paths for electrically interconnecting said positive lead of one of said light emitting diodes (28) to said negative lead of another of said light emitting diodes (28),

a heat sink having a base (36) overlying said second surface and a shell (38) extending forwardly from said base (36) in front of said light emitting diodes (28) for conducting heat forwardly of said first surface of said circuit board (26) and

a traffic light housing (10) presenting a light opening and a sun hood (24) extending from said opening, a casing (42) surrounding surrounding said base and mounted in said opening with said shell (38) extending forwardly within and spaced from said sun hood (24).

8. An assembly as set forth in claim 7 including a plurality of holes through said board (26), a plurality of pads (50) of thermally conductive plating on said second surface with each pad associated with one of said holes, and a thermally conductive material extending through said holes and thermally connecting each of said pads (50) and one of said leads (30, 32) to conduct heat from each of said leads (30, 32) to one of said pads (50) while maintaining electrical isolation between said pads (50).

9. An assembly as set forth in claim 7 including a casing (42) surrounding said base (36) of said heat sink, insulating material (44) disposed between said base (36) and said casing (42) to limit heat transfer to said heat sink from outside said casing (42).

10. An assembly as set forth in claim 7 wherein said shell (38) includes perforations (40) therein for radiating heat.