Abstract:
A light module is removably coupleable to a light fixture and includes an LED lighting element mounted on a mounting base that is operatively coupled to a housing. The light module also includes one or more resilient members that operatively couple the mounting base to the housing and allow the mounting base and housing to resiliently move relative to each other. The resilient members compress when the light module is removably coupled to the light fixture to exert a generally axial force on the mounting base to drive the mounting base into resilient contact with a surface of the light fixture to provide a thermal coupling between the light module and the light fixture.

Description:
PRIOR APPLICATION 
     This application claims the benefit of priority to U.S. Provisional Patent Application No. 60/809,569, filed May 30, 2006, the entire contents of which are hereby incorporated by reference in their entirety. 
    
    
     BRIEF DESCRIPTION 
     1. Technical Field 
     The present invention is directed to a lighting assembly which may include passive cooling components integrated therein. 
     2. Background 
     Lighting assemblies such as lamps, ceiling lights, and track lights are important fixtures in any home or place of business. Such assemblies are used to not only illuminate an area, but often also to serve as a part of the décor of the area. However, it is often difficult to combine both form and function into a lighting assembly without compromising one or the other. 
     Traditional lighting assemblies typically use incandescent bulbs. Incandescent bulbs, while inexpensive, are not energy efficient, and have a poor luminous efficiency. To attempt to address the shortcomings of the incandescent bulbs, a move is being made to use more energy efficient and longer lasting sources of illumination, such as fluorescent bulbs and light emitting diodes (LEDs). Fluorescent bulbs require a ballast to regulate the flow of power through the bulb, and thus can be difficult to incorporate into a standard lighting assembly. Accordingly, LEDs, formerly reserved for special applications, are increasingly being considered as a light source for more conventional lighting assemblies. 
     LEDs offer a number of advantages over incandescent and fluorescent bulbs. For example, LEDs produce more light per watt than incandescent bulbs, LEDs do not change their color of illumination when dimmed, and LEDs can be constructed inside solid cases to provide increased protection and durability. LEDs also have an extremely long life span when conservatively run, sometimes over 100,000 hours, which is twice as long as the best fluorescent bulbs and twenty times longer than the best incandescent bulbs. Moreover, LEDs generally fail by a gradual dimming over time, rather than abruptly burning out, as do incandescent bulbs. LEDs are also desirable over fluorescent bulbs due to their decreased size and lack of need of a ballast, and can be mass produced to be very small and easily mounted onto printed circuit boards. 
     LEDs, however, have heat-related limitations. The performance of an LED often depends on the ambient temperature of the operating environment, such that operating an LED in an environment having a moderately high ambient temperature can result in overheating the LED, and premature failure of the LED. Moreover, operation of an LED for extended period of time at an intensity sufficient to fully illuminate an area may also cause an LED to overheat and prematurely fail. Accordingly, an important consideration in using an LED in a lighting assembly is to provide adequate passive or active cooling. 
     Active cooling mechanisms, such as fans, may be difficult to implement in a lighting assembly, as they often increase the size and power consumption of the assembly, and drain additional power. Passive cooling structures, such as heat sinks, may also be difficult to incorporate as they increase the size of the lighting assembly. Moreover, traditional heat sinks can be as much of a detriment to incorporation in traditional lighting assignments as a ballast can be in a fluorescent bulb assembly. Accordingly, there is a need for providing adequate cooling in a lighting assembly, such as an LED lighting assembly, without significantly increasing the size, and without taking away from the aesthetics and ambience that a lighting assembly can add to an area. 
     BRIEF SUMMARY 
     Consistent with the present invention, there is provided a lighting assembly comprising a light module including a lighting element; an enclosure having a recess for receiving and housing the light module; a thermally conductive core connected to the light module through the enclosure; and a housing mounted in thermal contact with the core and the enclosure, so as to cause the housing to dissipate heat to an ambient atmosphere. 
     Consistent with the present invention, there is also provided a method for manufacturing a lighting assembly, comprising affixing a top core portion of a thermally conductive core to a bottom enclosure portion of an enclosure using a thermally-conductive adhesive; affixing a housing to a bottom core portion of the thermally-conductive core using a thermally-conductive adhesive; resiliently mounting a light module, including at least one lighting element, on a top enclosure portion in a recess of the enclosure using spring compression; and attaching a protective cover to the enclosure to enclose the light module. 
     Also consistent with the present invention, a light module is provided for use in a lighting assembly. The light module comprises a mounting base positioned on the lighting assembly, a first thermally conductive material positioned between the lighting assembly and the mounting base, a lighting element mounted on the mounting base, a second thermally conductive material positioned between the lighting element and the mounting base, and a resilient mounting component removably affixing the light module in the lighting assembly. 
     Additional features and advantages consistent with the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The features and advantages consistent with the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment consistent with the invention and together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a lighting assembly consistent with the present invention; 
         FIG. 2  is an exploded view of the lighting assembly of  FIG. 1 ; 
         FIG. 3A  is an exploded view of a light module of  FIG. 2 ; and 
         FIG. 3B  is side view of the light module of  FIG. 3A . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the exemplary embodiments consistent with the present invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIG. 1  is an illustration of a lighting assembly  100  consistent with the present invention. In one embodiment, lighting assembly  100  includes a protective cover  10 , an enclosure  20 , a housing  30 , and a core  40 . Further consistent with the present invention, lighting assembly may also include a light module  60 , as illustrated in  FIGS. 3A and 3B . 
     In some embodiments consistent with the present invention, lighting assembly may also include a mounting bracket  50 , and a power cable  52 . Mounting bracket  50  may be used to mount lighting assembly  100  to a stationary fixture, such as a wall, a light stand, or a ceiling. In an embodiment consistent with the present invention, mounting bracket  50  may be used to mount lighting assembly  100  to a track used in a track lighting fixture. Power cable  52  may be used as a connector to provide power from an external power source to lighting assembly  100 . 
       FIG. 2  is an exploded view of the lighting assembly of  FIG. 1 . As shown in  FIG. 2 , cover  10  may be attached to enclosure  20  enclosing light module  60  therein. Although light module  60  is not fully illustrated in  FIG. 2 , it is fully illustrated in  FIGS. 3A and 3B . The placement of light module  60  in relation to protective cover  10  and enclosure is shown in  FIG. 2  for illustrative purposes only using dotted lines. 
     Returning to  FIG. 2 , cover  10  may include a main aperture  12  formed in a center portion of cover  10 , a transparent member, such as a lens  14  formed in aperture  12 , and a plurality of peripheral holes  16  formed on a periphery of cover  10 . Lens  14  allows light emitted from a lighting element to pass through cover  10 , while also protecting the lighting element from the environment. Lens  12  may be made from any transparent material to allow light to flow therethrough with minimal reflection or scattering. Consistent with the present invention, cover  10 , enclosure  20 , endow. % housing  30 , and core  40  may be formed from materials having a high thermal conductivity. Cover  10 , enclosure  20 , housing  30 , and core  40 , may be formed from the same material, or from different materials. For example, in one embodiment consistent with the present invention, cover  10 , enclosure  20 , housing  30 , and core  40  are formed from the same material, such as a material having a thermal conductivity greater than 80 W/mK. Consistent with the present invention the material may be aluminum, or anodized aluminum. 
     Peripheral holes  16  may be formed on the periphery of cover  10  such that they are equally spaced and expose portions along an entire periphery of the cover  10 . Although a plurality of peripheral holes  16  are illustrated, embodiments consistent with the present invention may use one or more peripheral holes  16  or none at all. Consistent with an embodiment of the present invention, peripheral holes  16  are designed to allow air to flow through cover  10  and over light module  60  to dissipate heat. Consistent with another embodiment of the present invention, peripheral holes  16  may be used to allow light emitted from light module  60  to pass through peripheral holes  16  to provide a corona effect on cover  10 . 
     Enclosure  20  may include a recess  21  wherein light module  60  is removably mounted. Enclosure  20  may also include a mounting ring  22  having a plurality of electrical contacts  23  attached thereon using fasteners  24 . A power source opening  25  may be formed on a periphery of enclosure  20 , and a power source grommet may be attached to power source opening  25  for receiving power source cable  52  and establishing an electrical connection with electrical contacts  23 . In embodiments consistent with the present invention, power source cable  52  may be fixably attached to enclosure  20 , however in other embodiments consistent with the present invention, power source cable  52  may be removably attached to enclosure  20 . 
     Fastening holes  26  may be further formed on a periphery of enclosure  20  for use in fastening mounting bracket  50  to enclosure  20  using fastening screws  27 . Ventilation holes  28  may also be formed on a bottom surface of enclosure  20  for allowing air to flow over light module  60  and out to an ambient atmosphere or through housing  30  and then out to an ambient atmosphere, thereby passively assisting in cooling light module. 
     Consistent with an embodiment of the present invention, electrical contacts  23  provide an electrical connection to light module  60  when light module is mounted therein. Contact pads (not illustrated) may be attached to a bottom surface of light module  60  for establishing an electrical connection with electrical contacts so that when power source cable  52  is plugged into enclosure  20 , power is provided through power source cable  52  to electrical contacts  23  and into light module  60  through the contact pads. 
     Consistent with the present invention, light module  60  may be removable from the enclosure using, for example, plug-in connections. Removable light module  60  may allow a user to safely remove power from light module  60  so that the user can then remove light module  60  and replace, repair, calibrate, or test light module  60 . Specifically, light module  60  may be formed to be replaceable, allowing a user to replace light module  60  without having replace any of the other components of lighting assembly  100 . Moreover, light module  60  may be removed and replaced while lighting assembly  100  remains mounted. 
       FIG. 2  further illustrates a thermally-conductive core  40 . Consistent with the present invention, core  40  may have a spike shape, or a “T” shape. Consistent with the present invention, core  40  may be affixed to a bottom surface of enclosure  20  using a thermally-conductive adhesive (not illustrated). In one embodiment consistent with the present invention, the thermally-conductive adhesive may be a SE4486 CV Thermally Conductive Adhesive manufactured by Dow Corning Corporation, although other thermally-conductive adhesives may be used. 
     Consistent with the present invention, core  40  acts as a conduit for conducting heat produced by light module  60  through enclosure  20  and out to an ambient atmosphere through portions of housing  30  and through an end portion of core  40 . 
     Housing  30  may be made from an extrusion including a plurality of surface-area increasing structures, such as ridges  32 . Ridges  32  may serve multiple purposes. For example, ridges  32  may provide heat dissipating surfaces so as to increase the overall surface area of housing  30 , providing a greater surface area for heat to dissipate to an ambient atmosphere over. That is, ridges  32  may allow housing  30  to act as an effective heat sink for lighting assembly  100 . Moreover, ridges  32  may also be formed into any of a variety of shapes and formations such that housing  30  takes on an aesthetic quality. That is, ridges  32  may be formed such that housing  30  is shaped into an ornamental extrusion having aesthetic appeal. For example, housing  30 , as shown in  FIG. 2 , has a floral shape, with ridges  32  formed as flutes. However, housing  30  may be formed to have a plurality of other shapes. Accordingly, housing  30  may function not only as a ornamental feature of lighting assembly  100 , but also as a heat sink for cooling light module  60 . 
     Housing  30  may also include a plurality of housing holes  34 , which are formed to extend from a top portion of housing  30  (to the left in  FIG. 2 ) through a bottom portion of housing  30  (to the right in  FIG. 2 ). Housing holes  34  are formed to not only reduce the weight of housing  30 , but also to further increase the air flow through lighting assembly  100 . Thus, air may flow through periphery holes  16 , over light module  60 , through ventilation holes  28  and through housing holes  34  to be dissipated into an ambient atmosphere through a bottom portion of housing  30 , or to be dissipated through housing  30  into the ambient atmosphere. In one embodiment consistent with the present invention, housing holes  34  are formed such that they are in alignment with ventilation holes  28 . 
     Consistent with the present invention, housing  30  may further include a core hole  36  which extends from a top portion of housing  30  through a bottom portion thereof (to the right in  FIG. 2 ). Core hole  36  may receive a bottom portion of core  40  such that housing  30  may be affixed to core  40 . Consistent with an embodiment of the present invention, housing  30  may be affixed to core  40  using a thermally-conductive adhesive. The thermally-conductive adhesive may be a SE4486 CV Thermally Conductive Adhesive manufactured by Dow Corning Corporation, although other thermally-conductive adhesives may be used. 
     Housing  30  may be affixed to core  40  such that a top surface of the top portion of housing  30  is flush with a bottom surface of enclosure  20 , thereby establishing secure thermal contact between housing  30  and enclosure  20 . A thermally-conductive adhesive may further be used to resiliently establish the thermal contact between housing  30  and enclosure  20 . Establishing a secure thermal contact between housing  30  and enclosure may aid in cooling light module  60 . For example, a top surface of ridges  32  may be mounted flush against a bottom portion of enclosure  20  such that heat generated by light module  60 , which is resiliently mounted in recess  21  of enclosure  20 , is conducted through the bottom portion of enclosure  20 , into ridges  32 , and then dissipated into the ambient atmosphere. 
       FIG. 3A  is an exploded view of a light module consistent with the present invention. As shown in  FIG. 3A , light module  60  includes, from top to bottom, a detachable protective shroud  61 , a tapered optical element, or reflector  62 , a first circuit board  63  having a first circuit board hole  64  formed therein, a lighting element  65 , a second circuit board  66  having a second circuit board hole  67  formed therein, resilient mounting components  68 , and a mounting base  69 . 
     As shown in  FIG. 3A , first circuit board  63  may be stacked on second circuit board  66 , and may be formed to have a first circuit board hole  64 , wherein tapered optical element  62  is mounted thereon to extend through first circuit board hole  64 . Consistent with the present invention, tapered optical element  62  may be formed such that it has a top portion which is wider than a bottom portion, such that the bottom portion is able to extend through first circuit board hole  64 . Moreover, tapered optical element  62  may comprise a plurality of reflective surfaces formed on an interior surface to direct light emitted from lighting element  65 , and/or provide additional protection for lighting element  65 . 
     Second circuit board  66  may be formed such that second circuit board hole  67  receives a top portion  69 A of mounting base  69 . Consistent with the present invention, mounting base  69  may be formed such that top portion  69 A is narrower than a bottom portion, allowing top portion  69 A to extend through second circuit board hole  67 . Moreover, mounting base  69  may formed from a material having a high thermal conductivity. Consistent with the present invention, mounting base  69  may be formed from copper. Lighting element  65  may then be mounted on top surface  69 A of mounting base  69 . 
     As shown in  FIG. 3A , lighting element  65  includes a light emitting diode (LED) chip  70 . Although the illustrated embodiment uses an LED as a lighting element, consistent with other embodiments of the present invention, other lighting elements may also be used. LED chip  70  may comprise a chip having at least one light emitting diode device mounted thereon. For example, LED chip  70  may comprise an OSTAR 6-LED chip manufactured by OSRAM GmbH, having an output of 400-650 lumens. 
     Lighting element  65  may then be mounted on mounting base  69  using fasteners  71 , which may be screws or other well-known fasteners. Positioned between lighting element  65  and mounting base  69  is a first thermally-conductive material  72 , which acts as a void-filler between lighting element  65  and mounting base  69 . Essentially, the machining of both the bottom surface of lighting element  65  and mounting base  69  during the manufacturing process may leave minor imperfections in these surfaces, forming voids. These voids may be microscopic in size, but may act as an impedance to thermal conduction between the bottom surface of lighting element  65  and top surface  69 A of mounting base  69 . First thermally-conductive  72  material then acts to fill in these voids to reduce the thermal impedance between lighting element  65  and mounting base  69 , resulting in improved thermal conduction. Moreover, consistent with the present invention, first thermally-conductive material  72  may be a phase-change material which changes from a solid to a liquid at a predetermined temperature, thereby improving the gap-filling characteristics of first thermally-conductive material  72 . For example, thermally-conductive material  72  may include a Hi-Flow 225F-AC phase-change material, manufactured by The Bergquist Company, which is designed to change from a solid to a liquid at 55° C. 
     Mounting base  69  having lighting element  65  mounted thereon is then resiliently mounted to the stacked first circuit board  63  and second circuit board  66  using resilient mounting components  68 . Consistent with the present invention, mounting base  69  may be mounted to the stacked first circuit board  63  second circuit board  66  using resilient mounting components  68  prior to mounting lighting element  65  on mounting base  69 . 
     Resilient mounting components  68  may be located so as to mount mounting base  69  to the stacked first and second circuit boards  63  and  66  and provide a substantially even clamping force across the surfaces of lighting element  65  and mounting base  69 . By using resilient mounting components  68 , the thermal impedance caused by voids between lighting element  65  and mounting base  69  are minimized, and thermal conductivity is improved. In the embodiment illustrated in  FIG. 3A , resilient mounting components  68  may comprise compression spring members. Other embodiments consistent with the present invention may also be provided, in which resilient mounting components  68  may comprise elastic members, such as, for example, rubber tubing members. 
     A bottom surface of light module  60  may be mounted in recess  21  of enclosure  20  ( FIG. 2 ). Specifically, light module  60  may be mounted such that a bottom surface of mounting base  69  is in contact with a top surface of enclosure  20  in recess  21 . Consistent with the present invention, a second thermally-conductive material  73  ( FIG. 3A ) may be positioned between mounting base  69  and enclosure  20  to minimize thermal impedance therebetween, similar to first thermally-conductive material  72 . Second thermally-conductive material  73  may also be a phase-change material, such as a Hi-Flow 225UF manufactured by The Bergquist Company. 
     Consistent with the present invention, second circuit board  66  may have at least one secondary LED  74  mounted on a back surface. As shown in  FIG. 3A , second circuit board  66  has a plurality of secondary LEDs  74  mounted on a back surface. Consistent with the present invention, secondary LEDs  74  may be attached to the second circuit board  66  such that they are aligned with ventilation holes  28  ( FIG. 2 ). Such an arrangement may allow secondary LEDs  74  to emit secondary light which passes through ventilation holes  28  and illuminates housing  30  and ridges  32 . The secondary light may further cast shadows on an area behind lighting assembly  100  in the shape of housing  30 , increasing the aesthetic effect provided by lighting assembly  100 . 
     Detachable protective shroud  61  may also be mounted on lighting element  65  to protect tapered optical assembly  62 , and other components on the first and second circuit boards. Consistent with one embodiment of the present invention, detachable protective shroud is made from a synthetic material, and is mounted such that it rests upon a top surface of first circuit board  63 . 
       FIG. 3B  is side view of the light module showing a gap  75  between first and second circuit boards, consistent with the present invention. As shown in FIG.  3 B, light module  60  is assembled such that there is a predetermined gap having a distance d between first circuit board  63  and second circuit board  66 . Although light module  60  is illustrated in  FIGS. 3A and 3B  as having two circuit boards, in embodiments consistent with the present invention, light module may be formed to have one circuit board, or more than two circuit boards. Moreover, in other embodiments consistent with the present invention, light module  60  may have a micro fan mounted thereon to actively cool lighting element  65 , or a passive heat sink mounted on a circuit board to passively cool lighting element  65 . Furthermore, embodiments consistent with the present invention may use a combination of heat sinks and fans mounted on light element  65 , and other combinations of active and passive cooling components. 
     Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.