Patent Publication Number: US-2010109499-A1

Title: Par style lamp having solid state light source

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     BACKGROUND 
     The present invention relates to lighting systems, and more particularly relates to PAR style lights having solid state light sources. 
     Parabolic aluminized reflector (PAR) style lamps have historically been used to provide general ambient illumination over a sizable area. Conventional PAR style lamps typically include an incandescent light source surrounded by a housing and covered by a transparent lens. While incandescent PAR style lamps are operable to provide generally oval pools of ambient light for their intended purpose, they are associated with several disadvantages. 
     For instance, the incandescent light sources are relatively energy inefficient, requiring 50 W of power or more during operation. Furthermore, they are subject to color inconsistencies. For instance, as the inert gas in the light source ages, the emitted light can fluctuate between warm colors (having red hue) and cool colors (having a blue hue). Moreover, incandescent light sources emit ultraviolet light which has damaging color fading effects on pictures, paintings, and like light-sensitive objects. Additionally, the incandescent light sources having fixed output patterns which emit oval pools of light with unfocused edges, and is incapable of being easily manipulated. 
     What is therefore needed is a PAR style lamp that overcomes the disadvantages associated with conventional PAR style lamps. 
     SUMMARY 
     In accordance with one illustrative embodiment, a PAR style lamp includes a PAR-shaped housing, and an electrical contact supported by the housing. The electrical contact is configured to receive input power. The lamp further includes an illumination assembly disposed in the housing and electrically connected to the electrical contact. A heat dissipation assembly is carried by the housing. The heat dissipation assembly is in thermal communication with the illumination assembly, and the heat dissipation assembly is electrically isolated from the illumination assembly. The lamp further includes a lens configured to allow light emitted by the illumination assembly to pass through into an ambient environment. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description, is better understood when read in conjunction with the appended drawings. There is shown in the drawings example embodiments of various embodiments, however the present invention is not limited to the specific methods and instrumentalities disclosed. In the drawings: 
         FIG. 1  is a top perspective view of a PAR style lamp constructed in accordance with one embodiment; 
         FIG. 2  is a bottom perspective view of the PAR style lamp illustrated in  FIG. 1 ; 
         FIG. 3  is a side elevation view of the PAR style lamp illustrated in  FIG. 1 ; 
         FIG. 4  is an exploded perspective view of the PAR style lamp illustrated in  FIG. 1 ; 
         FIG. 5  is a top plan view of the PAR style lamp assembled as illustrated in  FIG. 4 , but with the lens and the housing removed; 
         FIG. 6  is a sectional elevation view of the PAR style lamp taken along line  6 - 6  of  FIG. 5 , and as assembled as illustrated in  FIG. 4 , but with the housing removed and only a portion of the lens shown; 
         FIG. 7  is a side elevation view of the PAR style lamp assembled as illustrated in  FIG. 4 , but with the housing removed to illustrate internal components of the lamp; 
         FIG. 8  is a side elevation view of the PAR style lamp similar to  FIG. 7 , but showing additional portions of the housing; 
         FIG. 9  is a sectional elevation view of the PAR style lamp illustrated in  FIG. 8 , taken along line  9 - 9 ; 
         FIG. 10  is a sectional elevation view of the PAR style lamp illustrated in  FIG. 3 , taken along line  10 - 10 ; 
         FIG. 11  is a schematic illustration of the electronic circuitry of the PAR style lamp illustrated in  FIG. 1 ; and 
         FIG. 12  is a top perspective view of a PAR style lamp constructed in accordance with an alternative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Referring to  FIGS. 1-4 , a solid state PAR style lamp  20  constructed in accordance with one embodiment extends along a centrally disposed longitudinal axis L-L, and includes a PAR-shaped housing  22  having a neck  24  at a lower end, and an opposing open upper end  28 . The housing  22  retains or carries a driver assembly  50  that receives power from a power source and converts the power as desired, an illumination assembly  26  that receives the converted power and provides illumination, a heat dissipation assembly  80  that allows heat generated during operation of the lamp to escape, and an electrical isolation assembly  23  that allows heat to transfer between the illumination assembly  26  and the heat dissipation assembly  80  while preventing electrical current from flowing between the illumination assembly  26  and the heat dissipation assembly  80 . 
     The housing  22  can be made from any suitable polymer such as polycarbonate or other electrically nonconductive material. The neck  24  can be connected to a conventional base  30 , for instance what is typically known as an Edison screw base, which is configured to be threadedly received in a conventional PAR lamp socket (not shown) to facilitate power transfer to the light source(s). The open upper end  28  can be closed with an end cap assembly  31  having an output lens  32  that can be transparent or semitransparent to allow light emitted by the illumination assembly to pass through to the ambient environment. The lens  32  can be colored, textured, or include any light altering characteristic if desired. In the illustrated embodiment, the lens  32  is made of a clear plastic, though any suitable alternative material could be used. The illumination assembly  26  can include at least one, for instance one or more, solid state light sources provided as LEDs  40  that direct light through the output lens  32 . 
     The lamp  20  is described herein as extending axially along the longitudinal axis L-L, and radially along a direction perpendicular to the longitudinal axis L-L. It should be appreciated that the longitudinal axis is referred to herein as extending along a vertical plane, and that the radial axis is referred to herein as extending along a horizontal plane, it being appreciated that the planes that encompass the various directions may differ during use, depending, for instance, on the desired directional and angular orientation of the links. Accordingly, the terms “vertical” and “horizontal” are used to describe the linkage as illustrated merely for the purposes of clarity and convenience, it being appreciated that these orientations may change during use. 
     As described herein, those components that are disposed in closer proximity to the longitudinal axis L-L other components are referred to as being disposed “inwardly” or “radially inwardly” or “inboard” with respect to the other components, while components that are disposed further from the longitudinal axis than other components are referred to as being disposed “outwardly” or “radially outwardly” or “outboard” with respect to the other components. Furthermore, the directional term “above” is used with reference to a direction from the base  30  towards the lens  32  along the longitudinal axis L-L, and the directional term “below” is used with reference to a direction from the lens  32  toward the base  30 . Accordingly, those components closer proximity to the lens with respect to a distance along a longitudinal axis than another component can be said to be disposed “above” the other component, and vice versa. These directional terms are used for the purposes of form and clarity, it being appreciated that the actual position of the components of the lamp may change depending on the orientation of the lamp  20  during use. 
     Moreover, while the lamp  20  is described with reference to axial and radial directions, the present invention is not intended to be limited to such geometric descriptions. Accordingly, unless otherwise specified, the geometric configuration of the lamp could alternatively be described with respect to rectangular directions in accordance with certain aspects of the invention. 
     With particular reference now to  FIG. 4 , the housing  22  defines a curved and substantially parabolic body  25  typical of PAR style lamps. The body  25  includes the substantially cylindrical neck  24 , a first curved portion  42  that flares radially outwardly, and is concave with respect to a horizontal plane (not shown) extending through the neck  24 , and a second curved portion  44  that curves radially outwardly, and is convex with respect to a horizontal plane (not shown) extending through the neck  24 . The second curved portion  44  is connected to a substantially longitudinally extending lip  46  disposed at its upper end. 
     The body  25  defines a plurality vents in the form of apertures  84  extending radially through the body to provide heat dissipation during use, as will be described in more detail below. The body  25  defines an internal void  27  defined in part by the open upper end  28 . One or more engagement members  48  can be disposed on the housing  22 , and particular on the radially inner surface of the lip  46 . 
     In the illustrated embodiment, the engagement members  48  of the housing  22  can be in the form of recessed pockets having corresponding leading cam surfaces  49  positioned above the pockets. The engagement members  48  are thus configured to cooperate with, and receive, complementary engagement members  164  of lens  32  to affix the lens  32  at the open end  28  of the housing  22  and cover the internal void  27 . 
     The lamp  20  further includes a driver assembly  50  that is supported by the housing  22  and disposed inside the internal void  27 . In particular, the housing  22  includes a retainer wall  52  that extends above the neck  24  and is surrounded by the first curved portion  42  of the housing body  25 . As illustrated, the retainer wall  52  is annular and extends vertically and is concentric about the longitudinal axis L-L. The retainer wall  52  terminates at an upper end  54  that is disposed below the lip  28 , and is further disposed below the second curved body portion  44 . The retainer wall  52 , in combination with the housing body  25 , defines a cylindrical cavity  56  having a closed lower end and an open upper end. It should be appreciated however, that the retainer wall  52  can have any size and shape, and can be positioned anywhere in the housing  22  in any orientation as desired. 
     Referring also to  FIGS. 7 and 8 , the driver assembly  50  further includes an LED driver  60  having one end in electrical communication with the base  30  via electrical wires (not shown), and thus receives line power, or power from any suitable power source. The driver  60  further includes an electrical interface in the form of a receptacle  62  that provides power outlet configured to receive a plug  64  of electrical wires  120  that fits into the receptacle  62 . 
     The driver  60  can include a circuit board  61  that carries circuitry  190  (described below with reference to  FIG. 11 ) configured to manipulate the input power to achieve a desired output power to the light sources  40 . The power output from the driver  60  can be configured to match with the electrical characteristics of the LED light sources. The driver  60  can further include pulse width modulation (PWM) circuitry to facilitate changes in light output characteristics (for instance dimming) if desired, and can be configured to comply with UL Class II isolation. While the driver  60  is configured to control all LEDs in concert in accordance with one embodiment, it should be appreciated that the driver  60  can alternatively include more than one channel if it is desired to provide independent control of LEDs or arrays of LED groupings. 
     The driver assembly  50  can further include an insulative cover  66  that mechanically isolates the driver from the remaining components of the lamp  20 . The cover  66  can be in the form of a cylindrical plate  68  having a pair of flanges  70  extending down from the plate  68 . The flanges  70  can be radially recessed with respect to the radially outer edge of the cover  66  by a distance substantially equal to the thickness of the retainer wall  52 . The flanges  70  can assume any suitable geometric configuration, and is arc-shaped in accordance with one aspect of the invention, and sized slightly smaller than the retainer wall  52  such that the cover  66  can be press-fit in the retainer wall  52 . The cover  66  can be sized such that when it is attached to the retainer wall  52 , the outer edges of the cover  66  are substantially flush with the retainer wall  52 . 
     The cover  66  can further include one or more plates  67  that extend down from the plate  68  radially inward with respect to the corresponding flanges  70 . The plates  67  can attach to the circuit board  61  of the driver  60  via a screw or any alternative fastener to affix the driver to the cover  66  such that the driver extends down from the cover  66 . A central opening  74  extends axially through the cover  66  to provide clearance for the insertion of the electrical plug  64 . The driver  60  is attached to the cover  66  in a position such that the receptacle  62  is in alignment with the opening  74 . The opening  74  can be sized only slightly greater than, or substantially equal to, the receptacle such that the plug  64  can fit snugly into the opening  74  when inserted into the receptacle  62 . 
     Referring now to FIGS.  4  and  6 - 9 , The lamp  20  further includes a heat dissipation assembly  80 , which can include a heat sink  82  and one or more vents  84  extending through the housing body  25 . The heat sink  82  includes a body  86  having an annular hub  88 , a cylindrical disk  92  disposed at the upper end of the hub  88 , and a plurality of heat dissipation fins  94 . The vents  84  provide for ambient airflow around the heat sink to assist in heat dissipation. The heat sink body  86  can be made of injection molded aluminum, or any suitable alternative material capable of dissipating heat generated during operation of the lamp  20 . 
     The hub  88  extends between an open lower end  90  and an upper end that is closed by the cylindrical disk  92 . The disk  92  has a diameter greater than that of lower end of the hub  88  and less than that of the upper curved portion  44  of the housing  22 . The open lower end  90  can be cylindrical having an inner diameter slightly greater than or substantially equal to that of the retainer wall  52  and cylindrical plate  68 . The cylindrical disk  92  has a diameter that is sized less than that of the housing body  25  at the location in axial alignment with the disk  92  such that the heat sink  82  can fit inside the housing body  25 . 
     The plurality of heat dissipation fins  94  extend radially out from the cylindrical hub  88 , and further extend axially between the lower end  90  and the disk  92 . Twenty-four fins  94  equidistantly spaced 15° with respect to each other about the circumference of the hub  88  are provided, though it should be appreciated that any number of fins  94  may be provided as desired, and can be spaced regularly or irregularly about the hub  88 . The fins  94  can have an airfoil shape with respect to a radius extending toward the center of the heat sink  82 , however it should be easily appreciated that the fins could define any suitable alternative shape that provides for heat dissipation. In the illustrated embodiment, each fin  94  can include an outer surface  96  that has a decreasing radius of curvature in a direction from the disk  92  toward the lower end  90  to impart a parabolic shape onto the radially outer end of the body  86 . 
     The heat sink  82  includes a plurality of apertures extending axially through the disk  92 . For instance, a plurality of mounting apertures  98  is spaced about disk  92  that provide connection locations between the heat sink body  86  and other components of the PAR light  20 . The mounting apertures  98  can be sized to receive a plurality of fasteners, which can be threaded such as screws  100 . A central aperture  102  is radially aligned with the of the central opening  74  of the insulative cover  66 , and is sized sufficiently large to receive the plug  64  so that the plug can extend through the cylindrical hub  88  and into the receptacle in the manner described above. 
     The heat sink  82  can be installed in the housing  24  by sliding the open lower end  90  of the heat sink body  86  over the cylindrical plate  68  and the retainer wall  52  until the lower end of the body  86  abuts the first curved portion  42  of the housing  24 . When installed, the cylindrical disk  92  is disposed axially inward with respect to the housing lip  46  to provide space within the upper end of the void  27  for the insertion of the illumination assembly  26  and the electrical isolation assembly  23 , as will now be described. 
     In particular, referring to  FIGS. 4 ,  5 ,  6 , and  10 , the illumination assembly  26  can include a plurality of LED light sources  40  mounted onto a substrate  111 , which can be provided as a printed circuit board  110  that directs power emitted from the driver  60  to the light sources  40 , a corresponding plurality of optical lens assemblies  112  that can define optical characteristics of light emitted by the light sources  40 , and a diffuser  130  that can eliminate glare from the light output by the light sources  40 . 
     The circuit board  110  can be cylindrical in shape, and can be made from aluminum or any alternative suitable thermally conductive material. The circuit board  110  can have a diameter greater than that of the heat sink disk  92 , and less than the inner diameter of the lens  32 . The upper surface of the circuit board  110  includes electrical traces  114  each configured to connect to one of the light sources  40 . Six electrical traces  114  equidistantly spaced 60° with respect to each other about the circumference of the circuit board  110  are provided, though it should be appreciated that any number of traces  114  may be provided as desired based, for instance, on the desired number of light sources  40 , and can be spaced regularly or irregularly about the circuit board  110 . 
     While the lamp  20  includes six light sources  40  equidistantly spaced circumferentially in the illustrated embodiment, it should be appreciated that the lamp in accordance with the can include any number of light sources spaced equidistantly or irregularly with respect to each other. For instance,  FIG. 12  illustrates the lamp as including three equidistantly spaced light sources  40 . 
     The circuit board  110  can further include a centrally disposed aperture  116  extending vertically through the circuit board, and a pair of electrical terminals  118  disposed on opposing sides of the aperture  116  on the upper surface of the board  110 . The terminals  118  can electrically connect to the terminal ends of wires  120  that extend up from the plug  64 . The wires  120  thus extend up through the aperture  116  and connect to the terminals  118 . Electrical traces (not shown) extend through the circuit board  110  and electrically connect the terminals and the electrical traces  114  such that power output from the driver  60  is transmitted to the light sources  40  through the wires  120 , the terminals  118 , electrical traces, and electrical traces  114 . 
     The circuit board  110  can further include a plurality of connection locations in the form of mounting apertures  122  that extend vertically through the circuit board. In the illustrated embodiment, the mounting apertures  122  are threaded and vertically aligned with the mounting apertures  98  of the heat sink  82  to facilitate assembly of the PAR lamp  20 . A pair of locating apertures  123  can further extend vertically through the circuit board  110  to ensure that the circuit board is installed in the lens  32  at a desired position that provides proper alignment of the light sources in the illumination assembly  26 . 
     As described above, the light sources  40  can be provided as light emitting diodes in the illustrated embodiment having a base  124  and a dome  126  extending up from the base. The dome  126  encapsulates the diode, and can be transparent or translucent such that the emitted light can pass through. The dome  126  can be made from plastic or any alternative suitable material. The base  124  can be provided as a heat resistant plastic that houses an electrical contact configured to connect to one of the electrical traces  114  on the printed circuit board  110 . The base  124  can be square shaped as illustrated, or can comprise any suitable alternative geometry. 
     In one embodiment, the electrical contact of the light source  40  can be soldered to the trace such that the diode is in electrical communication with the electrical trace  114 . It should be appreciated, however, that any suitable mechanism for facilitating the connection of the light source  40  to the circuit board that places the diode in electrical communication with the electrical trace  114  is contemplated. 
     Referring now to  FIGS. 4 and 6 , a plurality of optical lens assemblies  112  can be provided if desired, corresponding in number to one or more of the light sources  40 . Accordingly, one or more, up to all, of the light sources  40  can be provided with a corresponding optical lens assembly  112  that shapes or forms the output light as desired. Each optical lens assembly includes a housing  129 , which can be made of a heat-resistant plastic, and a lens  131  disposed in the housing. The lens  131  can be transparent or translucent, and can be made from a plastic or suitable alternative material. The lens assemblies  112  provide user-replaceable lens elements  131  that change the beam spread of the emitted light. Accordingly, the lamp  20  can provide a user-configurable light output. 
     The lens assembly housing  129  can include a substantially cylindrical body  132  and one or more legs  134  extending down from the body  132 . The legs  134  can provide spacers configured rest on the upper surface of the printed circuit board  110  to provide a gap that accommodates the corresponding light source  40 . Referring also to  FIG. 10 , two of the opposing legs  134  are connected to a retention member in the form of a beam  136  that extends across the lower end of the housing  129 . The beam  136  defines an opening  138  that receives the base  124  of the corresponding light source  40 . The opening  138  can be square shaped, and sized only slightly greater than the base  124  such that the position of the light source  40  is locked in place in the lens assembly  130 . The housings  129  can be retained in place either by an adhesive, for instance epoxy (such as two-part epoxy commercially available from  3 M), that attaches the housings to the circuit board  110  (or alternatively the lens  32 ). Alternatively, the housings  129  can be sandwiched between the circuit board  110  and lens  32  such that a sufficient force is placed on the housings  129  that prevent them from moving within the end cap assembly  31 . 
     The lens  131  can be provided in any desired size and shape. As best shown in  FIG. 6 , the illustrated embodiment includes a lower frustum portion  140  and an upper cylindrical portion  142  extending up from the lower frustum portion. The upper cylindrical portion  142  has a diameter only slightly less than that of the lens assembly housing  129  such that the lens  131  can be press-fit inside the housing  129 . When the lens is installed, the apex  141  of the lower frustum portion  140  is aligned with the opening of the beam  136 . The apex  141  of the frustum portion  140  can be provided as a recess that is sized to receive the upper end of the dome  126  of the light source  40 . Accordingly, during operation, light emitted from the light source  40  travels through the lens  131  before being directed out the PAR style lamp  20 . The upper surface of the cylindrical portion  142  can be textured as desired to further define the output light characteristic. 
     Referring again to  FIGS. 4 and 6 , the diffuser  130  can be formed from any suitable plastic, and can be opaque or translucent and define any suitable alternative material properties suitable for eliminating glare from the light emitted by the light sources  40 . In the illustrated embodiment, the diffuser  130  includes a substantially cylindrical plate  150  having a lip  152  disposed at the lower end of the plate  150  that extends radially out from the plate  150 . In the illustrated embodiment, the plate  150  can be substantially dome-shaped and concave with respect to the printed circuit board  110 . 
     A plurality of annular walls  154  extends vertically through the plate  150 . The annular walls can correspond in number to the light sources  40 . Accordingly, in the illustrated embodiment, six annular walls  154  can be equidistantly spaced 60° with respect to each other about the circumference of the plate, corresponding in number to the light sources  40 , though it should be appreciated that any number of walls may be provided as desired, and can be spaced regularly or irregularly about the plate  150 . 
     Each annular wall  154  defines a lower end co-planar with the lip. Each annular wall  154  further defines an upper end arranged such that the upper ends of the annular walls are co-planar. Each annular wall  154  further defines an internal cylindrical cavity  156  that extends through the plate  150  and is sized greater than the lens assembly housing  129  such that the light sources  40 , and lens assembly  112  fit within the cavity  156 . During operation, the annular walls  154  can shield the light sources  40  from direct view and blend the entire lambertian output of the light sources  40  and remove the point source glare associated with wide viewing angles (for instance, greater than 45 degrees off axis). 
     The diffuser  130  can include a pair of locating pins  158  that extend down from the lower surface of the plate  150 . The locating pins  158  can be in alignment with the locating apertures  123  of the printed circuit board  110 , and sized slightly less than the apertures  123  such that the fingers can be press-fit in the apertures  123 . The pins  158  extend a distance below the lower ends  155  of the annular walls  154  a distance substantially equal to the vertical thickness of the printed circuit board  110  such that the pins  158  extend into, but not substantially below, the apertures  123 . 
     Referring again to  FIG. 4 , the end cap assembly  31  can include a lens  32  as described above, and can further include a gasket  170  and a retaining ring  180 . The gasket  170  is configured to attach to the lower end of the lens  32 , and the retaining ring  172  seals the end cap assembly  31  to prevent liquid from entering into the illumination assembly  26 . 
     The lens  32  includes a substantially cylindrical end plate  160  and a substantially annular wall  162  extending down from the radially outer end of the end plate  160 . The end plate  160  and annular wall  162  can be integrally formed, and made from any suitable material, for instance a polymer such as polycarbonate. An inner lip  163  (see  FIG. 6 ) can extend radially inward from the radially inner surface of the annular wall  162 , such that the lip of the lens  32  is configured to abut the upper surface of the lip  152  of the diffuser  130 , thereby locating the diffuser  130  in the end cap assembly  31  when the diffuser is installed in the end cap assembly  31 . The annular wall  162  further includes one or more engagement members  164  configured to mate with corresponding engagement members  48  on the housing  22  when the PAR light  20  is assembled. The engagement members  164  can be in the form of projections that are configured to ride along the cam surface  49  and into the pocket of the engagement members  48  to affix the lens  32  to the housing  22 . An outer lip  161  can project radially outward from the annular wall  162  at a location above the engagement members  164  so as to provide a stop that is configured to abut lip  46  of the housing  22  when the lens  32  is fully attached to the housing  22 . 
     The gasket  170  can be made of plastic such as polycarbonate, or any suitable alternative material. The gasket can include an annular body  172  having an inner diameter slightly greater than the diameter of the heat sink disk  92 , and an outer diameter sized to be substantially flush with that of the annular wall  162  of lens  32 . An outer axial lip  174  can extend upwards from the radially outer end of the annular body  172  of the gasket, and an inner axial lip  176  can extend upwards from the radially inner end of the annular body  172 . A groove  178  is thus disposed between the lips  174  and  176 . The outer lip  174  is positioned to abut the bottom edge of the annular wall  162  of the lens  32  such that the groove  178  faces the lower surface of the printed circuit board  110  when the end cap assembly  31  is assembled. The groove  178  can be sized and positioned such that a radially inner portion of the groove  178  overlies the radially outer end of the printed circuit board  110 , while the radially outer portion of the groove  178  is aligned with the bottom end of the annular wall  162  of the lens  32 . Alternatively, the entirety of the groove  178  can be substantially or entirely aligned with the bottom end of the annular wall  162  of the lens  32 . 
     The retaining ring  180  can be made of silicon or any suitable material capable of providing a seal for the end cap assembly  31 . The ring  180  can be an annular ring having a diameter sufficient to fit into the groove  178  such that a portion of the ring  180  abuts the radially outer end of the printed circuit board  110 , and a portion of the ring  180  abuts the bottom end of the annular wall  162 . The retaining ring  180  can be ultrasonically welded to provide a water tight seal between the gasket  170  and the lens  32 . 
     As described above, the PAR style lamp  20  includes an electrical isolation assembly  23 . The illustrated embodiment recognizes that the heat sink  82  is exposed to the ambient environment to better facilitate heat dissipation during operation of the PAR style lamp  20 . While the housing  22  guards the heat sink  82  with respect to tactile access by a user, the housing  22  may not prevent a user from touching the heat sink  82  in all instances. As a result, it is desirable to electrically isolate the printed circuit board  110  from the heat sink  82 . At the same time, it is desirable to allow heat emitted by the illumination assembly  26  to readily transfer to the heat sink  82  so that the heat can be dissipated into the environment. 
     The electrical isolation assembly  23  in the illustrated embodiment can provide for thermal conductivity between the illumination assembly  26  to the heat sink  82  while at the same time preventing electrical conductivity between the illumination assembly  26  and the heat sink. 
     The isolation assembly  23  can include a thermally conductive and electrically isolating member such as a flexible dielectric film  182  that can be cylindrical in shape and dimensioned to prevent direct mechanical contact between the printed circuit board  110  and the heat sink  82 . For instance, the film  182  can have a diameter slightly less than the inner diameter of the annular body  172  of gasket  170  such that the film  182  covers all, substantially all, or a portion of the lower surface of the printed circuit board  110  that extends radially inward from the gasket  170 . Accordingly, when the illumination assembly  26  and heat sink  82  are installed in the lamp  20 , the film  182  lays flat between and against the upper surface of the heat sink disk  92  and the lower surface of the printed circuit board  100 . In this regard, the film  182  can provide a spacer member disposed that prevents mechanical contact between the printed circuit board  110  and the heat sink  82  when both are installed in the housing  22 . 
     A central opening  184  can extend vertically through the film  182 , and is disposed at the center of the film in the illustrated embodiment. The opening  184  can be sized to receive the wires  120  (and/or plug) to facilitate an electrical connection between the driver  60  and the illumination assembly  26 . A plurality of apertures  186  also extends through the film  182 , and surrounds the central opening  184  at locations in alignment with the mounting apertures  98  and  122  of the heat sink  82  and printed circuit board  100 , respectively. The apertures  186  are sized to receive the fasteners  100 . 
     In the illustrated embodiment, the film  182  is made from a 900-S silpad commercially available from Bergquist Company, located at 18930 W. 78th Street, Chanhassen, Minn. 55317. While the film  182  has been found to achieve thermal conductivity and electrical isolation, it should be appreciated by one having ordinary skill in the art that any suitable alternative material capable of achieving these properties is contemplated. Furthermore, while the heat sink  82  and printed circuit board  100  abut the film  182  in the illustrated embodiment, one skilled in the any alternative configuration is contemplated that provides for heat transfer from the illumination assembly  26  to the heat sink  82 , and that further provides for electrical isolation between the illumination assembly  26  and the heat sink  82 . 
     In one embodiment, the film  182  can provide a breakdown voltage within a range having a lower end between and including approximately 1700 Vac and 2500 Vac, and an upper end between and including approximately 5000 and 6000 Vac. In one embodiment, the film  182  has a breakdown voltage of approximately 5000 Vac. The film  182  can further provide a thermal conductivity within a range having a lower end between and including approximately 0.9 W/m-K and 1.3 W/m-K, and an upper end between and including approximately 3.0 W/m-K and 3.5 W/m-k. In one embodiment, the film  182  has a thermal conductivity of approximately 1.6 W/m-k. 
     The isolation assembly  23  can include one or more fasteners  100  that can mechanically connect the heat sink  82  to the illumination assembly  26  and locate the heat sink within the housing  22 . The PAR style lamp  20  can further be configured such that the fasteners  100  do not establish a path of electricity between the illumination assembly  26  and the heat sink  82 . For instance, in the illustrated embodiment, the mounting apertures  98  of the heat sink  82  are sized substantially greater than the screw shank such that each shank can pass through the corresponding aperture  98  without making contact with the portion of the heat sink disk  92  that defines the aperture  98 . 
     A nonconductive washer  188  can have an inner diameter sized greater than the screw shank and less than the screw head. The outer diameter of the nonconductive washer  188  can be greater than the mounting aperture  98  of the heat sink. Accordingly, the washer  188  separates the fastener  100  from contact with the heat sink  82  when the screw  100  is inserted into the mounting apertures  122  of the printed circuit board  110 . Furthermore, as the screw  100  is tightened, the screw head biases the washer  188  against the bottom surface of the heat sink disk  92 , thereby creating a frictional retaining forces between the disk  92  and the surrounding washer(s)  188  and film  182  that prevent the heat sink  82  from moving and maintain the screws  100  in a position out of contact with the disk  92 . 
     Assembly of the PAR style lamp  20  will now be described. It should be appreciated that certain of the steps described below may be performed before or after some or all of the other steps, or even concurrent with some or all of the other steps, while certain other steps need not be performed at all in order to provide a PAR style lamp  20  constructed in accordance with certain aspects described herein. One having ordinary skill in the art will therefore appreciate that the description below describes an assembly of the PAR style lamp  20  in accordance with only one embodiment, and that substantial deviations are intended to fall within the spirit and scope of the present invention. 
     The illumination assembly  26  can be assembled by attaching the LED light sources  40  to the printed circuit board  110  such that the electrical contact of each light source  40  is placed in electrical communication with the electrical traces  114 . Next, the optical lenses  112  can be attached to the printed circuit board  110  such that the housing  129  surrounds the associated LED light sources  40 . The diffuser  130  can then be installed in the lens  32  such that the lip  152  of the diffuser plate  150  abuts a corresponding lip (not shown) that extends radially inward from the radially inner surface of the annular wall  162 . The diffuser  130  can thus be positioned such that the upper ends of the annular walls  154  are spaced slightly below (or could abut) the cylindrical end plate  160  of the lens  32 . 
     The distal end of wires  120  can be fed upward through the central opening  184  of the film  182 , and further through the central aperture  116  extending through the printed circuit board  110 , and can electrically connected to the terminals  118  disposed on the upper surface of the printed circuit board  110 . The circuit board  110  can then be inserted into the open lower end of the lens  32  such that the locating pins  158  of the diffuser extend into the corresponding locating apertures  123  that extend through the printed circuit board  110 . 
     Next, the retaining ring  180  can be placed in the groove  178  of the gasket  170 , and the gasket can be positioned such that the outer diameter of the annular body  172  is substantially flush with the annular wall  162  of the lens  32  and the retaining ring is at least partially aligned with the  10  with the bottom end of the annular wall  162  of the lens  32 . The retaining ring  180  can then be ultrasonically welded to provide a water tight seal between the gasket  170  and the lens  32 . 
     The driver assembly  50  can then be installed in the housing  22  by attaching the driver  60  to the insulative cover  66  such that the receptacle  62  of the driver  60  is aligned with the central opening  74  of the cover  66 . The driver  60  can then be inserted into the retainer wall  52 , and the upper end of the retainer wall can be closed by press-fitting the recessed flange  70  into the upper end of the retainer wall  52  until the cover  66  abuts the upper end of the retainer wall. 
     Next, the heat sink  82  can be mechanically connected to the illumination assembly  26 . In particular, the dielectric film  182  is placed flat against the bottom surface of the printed circuit board  110  such that the apertures  186  extending through the film  182  are aligned with the mounting apertures  122  of the printed circuit board  110 . The plug  64  of the electrical wires  120  can be inserted through the central aperture  102  of the heat sink  82 , and the heat sink can be positioned such that the upper surface of the heat sink disk  92  abuts the bottom surface of the dielectric film  182 . The heat sink  82  is oriented such that the mounting apertures  98  are aligned with the corresponding apertures  186  of the film  182 , and further aligned with the corresponding mounting apertures  122  of the printed circuit board  110 . 
     Next, the washers  188  can be positioned against the bottom surface of the heat sink disk  92  at each mounting aperture  98 , and the screws  100  can be inserted through the corresponding washers and the mounting apertures  98  so that the screw shanks do not contact the heat sink  82 . Furthermore, the washers  188  separate the screw heads from the heat sink disk  92 . As a result, the screws  100  do not contact the heat sink  82 . Once the screws  100  are inserted through the apertures  98 , they can be threadedly fastened to the mounting apertures  122  of the printed circuit board  110 . Because the screws  100  are electrically isolated from the heat sink  82 , electrical current is prevented from flowing from the circuit board  100  to the heat sink. 
     It should be appreciated that many deviations from the illustrated embodiment are contemplated. For instance, the screws  100  could alternatively be threaded into the mounting apertures  98  of the heat sink  82  and be isolated with respect to contact with the printed circuit board  110 . Alternatively still, the screws  100  can be made from a nonconductive material (for instance plastic) and can be threadedly inserted into both sets of mounting apertures  98  and  122  to electrically isolate the heat sink  82  and the circuit board  110 . Alternatively still, an adhesive or any alternative fastener could couple the heat sink  82  to the dielectric film  82 . Alternatively still, the heat sink  82  could be fastened to the housing  22  at a location that places the heat sink disk  98  against the dielectric film  82 . It should thus be appreciated that any retention member that locates the heat sink  82  in a position to be in thermal communication with, and electrically isolated from, the illumination assembly  26  is contemplated. 
     Once the heat sink  82  has been mechanically coupled to the illumination assembly  26 , the plug  64  can be inserted into the central receptacle  62  of the driver  60  via the opening  74  of the cover  66 , thereby placing the illumination assembly  26  in electrical communication with the base  30 . The end cap assembly  31 , which retains the illumination assembly  26 , and the heat sink  82  can then be inserted into the housing such that the cylindrical hub  88  of the heat sink  92  fits over the cover  66  and retainer wall  52 . The end cap assembly  31  is inserted until the engagement members  164  of the lens  32  mate with the complementary engagement members  48  of the housing  22 . The outer lip  161  is configured to abut the lip  46  of the housing  22  to prevent the lens  32  from being over-inserted. It should be appreciated that while the engagement members  48  are provided as pockets and engagement members  164  are provided as projections, any alternative engagement member suitable for attaching the lens  32  to the housing  22  is contemplated. 
     The base  30  provides an electrical contact that can be placed in electrical communication with an electrical power source, for instance by screwing the base  30  into a conventional socket, which causes power to transmitted through the driver  60  and circuit board  110  to the light sources  40  to illuminate the diode encapsulated by the dome  126 . Referring now to  FIG. 11 , the driver  60  can include a circuit board  61  having internal circuitry  190  that carries one or more elements configured to control power received from the base  30 . For instance, the circuitry  190  can include a varistor  191  that is configured to eliminate voltage spikes received from the power source, such as a 120V AC power source. A pair of capacitors  192  is provided in parallel that limit the current flow through the circuitry  190  and eventually to the light sources  40 . A resistor  193  can be provided to discharge the capacitors  192  so that a user will not be exposed to live voltage when the lamp  20  is removed from the power receptacle. 
     A full bridge rectifier  194  can be provided that converts the AC power to DC power of a predetermined amperage, for instance 35 mA. A third capacitor  195  can be provided that absorbs additional power spikes that happen to pass through the remaining upstream circuitry components. For instance, power spikes can occur when the light is initially turned on. A resistor  196  can be provided that is configured to drain the capacitor  195 . Finally, a pair of transient suppression diodes  196  can be arranged in parallel and configured to shunt current that is above a predetermined voltage to ground. The current then travels through the light sources  40  to illuminate the associated diodes of the light sources  40 . 
     During operation of the lamp  20 , as heat is produced by the illumination assembly  31 , and in particular by the light sources  40 , the heat travels through the circuit board  110  to the dielectric film  182 , and further through the dielectric film  182  to the heat sink  82 . The heat sink  82  dissipates the heat into the ambient environment through the vents  84  that are formed in the housing  22 . The fins  94  increase the surface area of the heat sink body  86 , thereby increasing the efficiency of heat dissipation. Because the dielectric film  182  is not electrically conductive, electricity is prevented from flowing from the illumination assembly  31  to the heat sink body  86 . The present inventors have found that in the illustrated embodiment, a power surge of up to 2500 VAC flowing through the printed circuit board  110  will not travel to the heat sink  82 . 
     While apparatus and methods have been described and illustrated with reference to specific embodiments, those skilled in the art will recognize that modification and variations can be made without departing from the principles described above and set forth in the following claims. Accordingly, reference should be made to the following claims as describing the scope of the present invention.