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LED CONNECTOR ASSEMBLY WITH HEAT
SINK
FIELD OF THE INVENTION
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The present invention is directed to electronic components, and more particularly to a universal holder assembly for light emitting diodes (LEDs).
BACKGROUND 10
The use of high intensity LEDs for general-purpose illumination, and in specialty lighting applications such as architectural and video display applications, has increased in recent years. Typically, manufacturers of LED lighting 15 assemblies design assemblies that are customized for the specific LED devices that are used in the illuminated displays. The electrical interconnections and thermal characteristics of the assemblies are often treated as secondary issues, and dealt with separately from the mechanical and esthetic aspects of 20 the lighting fixture. This frequently results in thermal and interconnection problems with the LED assembly packaging. The heat accumulation may damage the LEDs themselves, resulting in shorter useful life of the LEDs, or cause damage to the light fixture housings such as warping and discolora- 25 tion.
What is needed is a standard holder for high-intensity LEDs that integrates electrical and thermal connections in a single receptacle. Other features and advantages will be made apparent from the present specification. The teachings dis- 30 closed extend to those embodiments that fall within the scope of the claims, regardless of whether they accomplish one or more of the aforementioned needs
SUMMARY OF THE INVENTION 35
In one aspect, the present invention is directed to a universal mounting assembly. The mounting assembly supports high intensity LEDs in a lighting fixture. The mounting assembly includes a holder portion and a receptacle portion. 40 The holder portion includes a peripheral sidewall defining a cavity for accepting a printed circuit board assembly. A support member is disposed along the peripheral sidewall to support the printed circuit board assembly. A plurality of electrical contact elements are provided for connecting LEDs 45 mounted on the printed circuit board. A thermal conduction member is configured to thermally communicate with the printed circuit board assembly. The receptacle portion is configured to removably engage the holder portion. The receptacle portion has a plurality of contact sockets configured to 50 conductively engage the plurality of electrical contact elements of the holder portion, to interconnect the plurality of contact elements to external wires of the light fixture. An aperture is arranged in the receptacle portion to accept the thermal conduction member; wherein the thermal conduction 55 member passes through the aperture and into a space for dissipating heat from the printed circuit board.
In another embodiment, the present invention is directed to a universal mounting assembly for supporting high intensity LEDs in a lighting fixture. The mounting assembly has a 60 holder portion with a peripheral sidewall defining a cavity for accepting a printed circuit board assembly. At least one support member is disposed along the peripheral sidewall to support the printed circuit board assembly containing LEDs. A plurality of electrical contact elements is provided within 65 the holder portion to connect to external wires of the light fixture. A thermal conduction member is in thermal commu
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nication with the printed circuit board assembly. An aperture in the holder portion is arranged to accept the thermal conduction member. The thermal conduction member passes through the aperture and into a space for dissipating heat from the printed circuit board.
In another embodiment, the present invention is directed to a mounting assembly for supporting at least one high intensity LED in a lighting fixture. The mounting assembly has a first portion and a second portion. The first portion includes a frame portion and a plurality of integral electrical conductors. The integral electrical conductors are arranged about a perimeter of the frame for connection to corresponding electrical contact pads disposed on a PCB. At least one high intensity LED is mounted on the PCB. The second portion is retentively engageable in thermal contact with the first portion. The second portion extends axially from the first portion for dissipation of heat from the PCB disposed within the first portion. The second portion has a cavity to connect it to the first portion, and has at least one base portion of the second portion to support the first portion within the cavity.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded view of an LED connector assembly holder and socket connector.
FIG. 2 is a cross-sectional view of the assembled holder and socket connector.
FIG. 3 is a top plan view of the holder.
FIG. 4 is a cross-sectional view of the holder taken along the lines 3-3 in FIG. 2.
FIG. 5 is a bottom plan view of the holder.
FIG. 6 is a cross-sectional view of an alternate embodiment of the holder.
FIG. 7 is a cross-sectional view of another alternate embodiment of the holder.
FIG. 8 is an alternative embodiment of the LED connector assembly mounted on a PCB.
FIG. 9 is a socket connector mounted on a PCB.
FIG. 10 is an exploded view of an alternate embodiment.
FIG. 11 is a partial sectional view of the alternate embodiment of FIG. 10.
Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a universal LED connector assembly that accepts a conventional LED printed circuit board (PCB) containing at least one high intensity LED. The PCB can be of conventional construction, or may include thermally conductive cladding such as aluminum. Each LED circuit board represents a component or pixel of a larger image or light source. The LED connector assembly is designed to be independent of the actual LED device that is used. The LED PCBs are for use in various architectural and general-purpose lighting fixtures, signs and video displays, traffic signals and various other applications using high intensity LEDs. The lighting fixture typically provides a housing or structure that supports the LED light source. The structure provides power connections to the LED light source, and provides openings through which the light shines when the light source (or sources) is energized. When used herein, the word lighting
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fixture is meant to include all general and specific-application LED devices that employ high intensity LEDs, and not limited to lighting fixtures for building illumination. Examples of lighting fixtures include track mounted spotlights utilizing incandescent bulbs, and walkway lights using incandescent 5 or halogen bulbs.
Referring to FIGS. 1-5, an LED connector assembly 10 includes a holder portion 12 and a connector portion 14. The holder portion 12 removably engages the connector portion 14 by inserting contact pins 22 (see, e.g., FIG. 4) into sockets 10 24. An LED PCB assembly 16 is rigidly supported in a recess 26 of the holder portion. The LED PCB assembly 16 has at least one LED 28 mounted thereon, but may include several LEDs if desired. For example, a common configuration for the LED PCB assembly includes three LEDs of red, green and 15 blue (RGB) light for controllably varying the combinations to create virtually any color light. For each color another contact pair is required in the socket. For example, and RGB will require six individual contacts arranged around the outside of the LED PCB. 20
A heat sink 18 is supported within the holder portion 12 by an internal support ring 42, and is retained in position by a circular locking clip 30 or other similar spacer. The heat sink 18 contacts the bottom side of the LED PCB assembly 16 and extends downward below the bottom edge 32 of the holder 25 portion 12. The heat sink 18 extends into and through the connector portion 14 when the holder portion 12 is engaged, and provides a thermal path for dissipating heat generated by the LED PCB assembly 16. The heat sink may be constructed of any suitable thermal conductor. By way of example and not 30 by limitation, the heat sink material may be copper, aluminum or die-cast zinc. In an alternate embodiment, the heat sink 18 may also be a heat pipe. In the drawings the heat sink 18 is shown as a generally circular cylinder with a flat circular head portion 58, however, the shape may vary depending on the 35 application to provide additional exposed surface for heat dissipation. For example, the heat sink 18 may include heat fins, fluting, or other shapes for increased heat dissipation, as will be readily appreciated by those persons skilled in the art. Thermally conductive grease or thermally conductive pad 40 may be applied to the flange or head portion 58 to promote the transfer of heat from the LED PCB 16.
The LED PCB assembly 16 preferably snaps into position in the holder portion 12 and is retained by angled tips 60 of contact fingers 34 connected to contact pins 22. The contact 45 fingers 34 and contact pins 22 provide electrically conductive paths to lead wires 36a-36d, through contact sockets 24. A spring 38 applies compressive force between the heat sink 18 and the bottom of LED PCB assembly 16, while simultaneously applying a normal force to the contact fingers 34. A 50 washer 40 rests on the locking clip 30 and retains the spring 38 in position between washer 40 and LED PCB assembly 16.
Referring to FIG. 3, one or more LEDs 28 are electrically connected through the PCB assembly 16 to electrical interconnection pads 44 (See, e.g., FIG. 3) disposed at the periph- 55 ery of the PCB assembly 16 and aligned with the contact fingers 34 for locking engagement. There are two interconnection pads 44 required for each LED that is mounted on the LED PCB assembly 16. In the exemplary embodiment illustrated in FIG. 3, two LEDs can be accommodated by the four 60 interconnection pads 44 shown, although the PCB assembly 16 that is depicted includes only a single LED. More interconnection pads 44 may be added as required to accommodate the total number of LEDs. Likewise, the number of contact fingers 34 and sockets 24 must correspond with the 65 number of interconnection pads 44. The number of contacts that may be arranged around the periphery is only limited by
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the geometry of the PCB assembly 16. Additional interconnects may be used for communications or control wiring for one or more LED fixtures (not shown). A typical LED PCB assembly includes an LED light source mounted on a composite substrate of an electrically insulating top layer, e.g., FR4 ormicarta board, optionally including a metallic bottom layer for improved heat conduction, e.g., aluminum or copper. Bayonet lugs 20 are optionally formed on the holder portion 12 for attachment of the LED connector assembly 10 to a customer's light fixture lens assembly, or other structure into which the LED connector assembly is to be mounted. Alternate attachment means for the LED connector assembly may include threaded connections or snap-fit connections (not shown).
In another embodiment shown in FIG. 6, the heat sink 18 may be retained within the holder portion 12 by a molded shelf portion 46 of the internal support ring 42, replacing the locking clip 30 and washer 40 in the embodiment described above. Another arrangement for maintaining the position of the heat sink 18 is shown in FIG. 7. In this arrangement, a latching edge 48 engages with a rim portion 50 of the heat sink 18. The rim portion 50 is maintained against the latching edge 48 by spring 38. This arrangement has fewer parts by eliminating, for example, the washer and clip, and is therefore easier to assemble and to integrate into a lighting fixture. The PCB assembly floats between the contact fingers 34 and the heat sink 18. The contact fingers 34 apply downward force and the heat sink 18 applies opposite force to maintain the LED PCB assembly 16 in position, i.e., the heat sink 18 pushes upward against the LED PCB assembly 16.
The connector portion 14 may optionally be eliminated within the scope of the invention. Referring again to FIG. 4, the contact pins 22 may be eliminated and replaced with solder tails or press fit tails snap-in connectors. This would eliminate the need for a connector portion 14, which may be replaced by a substrate 52 (see, e.g., FIG. 8), by direct attachment to another PCB (not shown) or left unsupported. In the embodiment shown in FIG. 8, the alternate LED connector assembly 10a includes the PCB holder portion 12 mounted on a substrate 52, either by soldering or mechanical fasteners. A plurality of connector terminal portions 54 extends from the holder portion 12 through the substrate. External wiring (not shown) is connected to the connector terminal portions 54 to power the LEDs and any associated control or communications devices of the light fixture or device into which the LED connector assembly 10 is fastened. The heat sink 18 also protrudes below the substrate 52 and is exposed to an air space below for dissipating heat. The air space may include airflow driven by a fan to supplement or enhance the heat dissipation characteristics of the heat sink 18. The LED PCB assembly 16 snaps into position in the holder 10a.
Referring next to FIG. 9, the connector portion 14 may optionally be mounted on a substrate 52, and the holder portion 12 plugged into the connector portion 14, with terminal portions 54 extending from the opposite side of the substrate 52, and heat sink 18 protruding below the substrate as described above.
Referring next to FIGS. 10 and 11, an alternate embodiment of the LED connector assembly 10 has a modified heat sink 18 with a fluted shape that provides additional surface area for dissipating heat. In one embodiment, the heat sink 18 is designed with a complementary outer ring, similar to conventional halogen bulbs, e.g., types GULO or MR16 standard bulbs having outer rings on the reflector assembly, to permit the LED pixel assembly 10 to be directly substituted for the conventional bulbs. Alternately, the rear portion of the heat sink may be threaded (not shown) to fit into a threaded light
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