Abstract:
Concatenatable lighting fixtures, each comprising a unitary cover member having a circuit board mounting platform integrally formed with suitable heat sinking and which cover member mounts onto a cooperating base chassis. In one embodiment, the circuit board mounting platform extends farther from one end of the cover member than the other so as to facilitate placement of LEDs in a fashion which enhances lighting uniformity and minimizes dark spots. First and second guide members may be positioned in respective opposite ends of adjacent fixtures, each guide member having a plurality of extending fingers with a flexible electrical conductor-carrying conduit disposed between the respective opposite ends and retained in position by said fingers.

Description:
[0001]    This application claims the Paris Convention priority of U.S. Provisional Application No. 61/033,654 entitled “Modular LED Lighting Fixtures,” filed Mar. 4, 2008, the contents of which are hereby incorporated by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of Invention 
         [0003]    This invention relates to the field of lighting technology and more specifically, to the use of LEDs in commercial and residential lighting fixtures. 
         [0004]    2. Description of Related Art 
         [0005]    Incandescent lighting has a low efficiency since much of the electrical power supplied to such lighting is converted to heat instead of light. The cost of electricity is expected to increase in the future as the cost of producing electricity rises. LEDs (light emitting diodes) provide a much more efficient conversion of electrical energy from incandescent lighting and efforts are underway to employ more efficient and longer lasting LED lamps in various applications. 
       SUMMARY 
       [0006]    Embodiments hereafter disclosed provide a set of interconnected, modular LED lighting fixture components that can be arranged and easily installed in the field in a wide variety of forms and shapes to meet the needs of designers and architects. Various embodiments facilitate low cost, yet attractive designs using LED lighting fixtures suitable, for example, for cove lighting applications and readily installed in the field due to various features. One such feature is a field-installable unitary cover member having a circuit board mounting platform integrally formed with suitable heat sinking and which mounts onto a cooperating base chassis. In one embodiment, the circuit board mounting platform extends farther from one end of the cover member than the other so as to facilitate placement of LEDs in a fashion to maintain relatively uniform spacing of the LED lamps, thereby enhancing lighting uniformity and minimizing dark spots. Various combinations and adaptations of such features in various embodiments facilitate practical use of energy efficient, high power LED lighting technology at modest cost in attractive and easily field installed configurations for architects and designers. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The foregoing, and other features and advantages, will be apparent from the following, more particular description of the preferred embodiments of the invention made in conjunction with the accompanying drawings of which: 
           [0008]      FIG. 1  illustrates a frontal perspective view of two lighting fixture components interconnected together into an assembly; 
           [0009]      FIG. 2  shows a rear perspective view of the same assembly of two components of  FIG. 1 ; 
           [0010]      FIG. 3  is a top view of the two components of  FIG. 1 ; 
           [0011]      FIG. 4  is a bottom view of the two components of  FIG. 1 ; 
           [0012]      FIG. 5  is a perspective view of an electrical wiring conduit guide; 
           [0013]      FIG. 6  is a perspective view of the two fixture components of  FIG. 1  with one component cut away to illustrate internal features; 
           [0014]      FIG. 7  is an exploded perspective view of an alternate embodiment; 
           [0015]      FIG. 8  is an exploded perspective view of a second alternate embodiment; 
           [0016]      FIG. 9  is an exploded perspective view of a third alternate embodiment; 
           [0017]      FIG. 10  is an exploded perspective view of a fourth alternate fixture component embodiment; 
           [0018]      FIG. 11  is a top view of two fixture components according to the embodiment of  FIG. 10  joined together; 
           [0019]      FIG. 12  is a bottom view of the apparatus of  FIG. 11 ; and 
           [0020]      FIG. 13  is a perspective view of a cover component of the embodiment of  FIG. 10 . 
           [0021]      FIGS. 14 and 15  are schematic diagrams illustrating LED lamp placement according to two respective illustrative embodiments. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0022]    Further features and advantages, as well as the structure and operation of various embodiments are described in detail below with reference to the accompanying  FIGS. 1-8 , wherein like reference numerals refer to like elements. The embodiments are described in the context of several component designs with compatible electrical connectors and localized heat sinks. Nonetheless, one of ordinary skill in the art will readily recognize that other embodiments can use different forms and shapes, with different electrical connectors and other features. 
         [0023]      FIGS. 1-6  illustrate two generally elongated, box-shaped fixture components  140  and  180  which can be joined at selected arbitrary angles with respect to one another to provide highly configurable LED lighting arrangements. Each fixture component  140 ,  180 , contains a plurality of LED light emitting diodes  143 , with suitable heat sinking, e.g.  160 . The heat sink component  160 , as shown in  FIG. 1 , for example, is a unitary component bolted or otherwise fastened along its edges to the sides of each component  140 ,  180 . A printed circuit board  182  to which the LEDs  143  are mounted is then attached to the heat sink by suitable screws or other fastening devices or, in other embodiments, a suitable heat transfer adhesive. 
         [0024]    An elbow joint  146  is formed when the two components  140 ,  180  are joined by attaching a lower tongue  130  of one component  140  to a lower tongue  131  of the other component  180 . As shown in  FIGS. 4 and 12 , these lower tongues  130 ,  131  each extend the same length “L” from the respective edges, e.g.  162 ,  163  of the mating components  140 ,  180 . As may be seen in  FIG. 2 , the lower tongue  131  of the first fixture component  140  extends so as to underlie the mating lower tongue  130 , and these two tongues are attached together by a bolt, screw, or other mechanism  142 . Alternatively, a snap-fit pivot interconnection mechanism may be provided to interconnect the two lower tongues  130 , 131 . 
         [0025]    Each component  140 ,  180  further has a circuit board mounting platform  181 , which extends beyond the length of the box-shaped portion of the component at each end. A circuit board  182 , which, in the illustrative embodiment, has the same shape as the platform  181 , is mounted on top of the platform  181 , and has respective tongues  133 ,  134  at each end thereof. As illustrated in  FIGS. 3 and 11 , the extended length “A” of one of the tongues  134  of each circuit board  182  is selected to be equal to half of the width (½ “W”) of the circuit board  182 , while the extended length “B” of the opposite tongue  133  is selected to be equal to one and a half times the width ( 3/2 “W”) of the particular circuit board  182 . The distance “L 1 ” between the two extended lengths A, B is preferably the same for each of the circuit boards  182 . Thus, tongue  134  is shorter than tongue  133 . These different lengths allow the two components  140 ,  180  to be joined at an arbitrary angle with respect to one another of between, for example, −90 degrees and +90 degrees, while still maintaining the LED&#39;s of each of the components e.g. LED&#39;s  143   a ,  143   b , spaced close enough together to enhance the uniformity of illumination and to eliminate or considerably reduce the effects of dark spots, or so-called “scalloping”. While 90 degree bends are illustrated in the figures, 20 to 30 degree bends are more common in practice. In other embodiments, the extended lengths “A”, “B”, may be shorter or longer. 
         [0026]    To facilitate passage of electrical conductors between the two components  140 ,  180 , the elbow joint  146  includes a non-conductive flexible conduit  144  disposed between them. The conduit  144  provides a hollow tube through which current carrying wires, e.g.  171 ,  172  supplying a lamp driver unit  170  ( FIG. 6 ) are passed. The conduit  144  passes through and is maintained in position by first and second tubular nonconductive guides  188  and  148  and a tie wrap fastener  271  (e.g.  FIG. 2 ). The conduit  144  may be fabricated using Part No. SM-1216-HY tubing available from Sealcon Co. 
         [0027]      FIG. 5  illustrates one of the non conductive guides  188 , preferably formed of a suitable plastic, which support and guide the electrical wiring conduit  144 , allowing the assembly&#39;s elbow joint  146  to bend through a range of angles. The conductive guide  188  includes a base  143  having a circular opening  152  therein and from which projects two sets  102 , 103  of perpendicularly disposed and radically positioned fingers, which provide a bushing for supporting the conduit  144 . There are respective gaps  150  between the sets of fingers  102 ,  103 , which enable them to flex toward one another so as to firmly grasp a conduit section  144  when the tie wrap fastener  271  (e.g.  FIG. 2 ) is applied. Each of the fingers  102 ,  103  may have a lip or bulbous projection  109  formed on the outer surface of their respective ends  107 ,  108  to assist in retaining the tie wrap  271  in position. Nubs  145  are also provided on the outer surfaces of each of the fingers  102 ,  103  to further assist in positioning the tie wrap fastener  271 . 
         [0028]    As may be seen in  FIG. 6 , the base  143  of the guide  188  abuts an inner end surface  173  of a fixture component while the fingers  102 , 103  extend to capture a respective end of the flexible conduit  144 , which may then be fastened in place by a tie wrap fastener, e.g.  271 . 
         [0029]      FIG. 7  illustrates another embodiment wherein a unitary cover member  201  is adapted to snap onto a base  202  to form an enclosure for wiring  203  and an LED electrical driver circuit board  205  and attached componentry. The cover member  201  has generally rectangular parallel elongated sides  241 ,  242 , which may be mirror images of one another and which include an array of horizontally veined heat sink fins  243 ,  244 . 
         [0030]    The snap-on mechanism may be achieved by providing suitable tabs, tangs, or lips  207  positioned on the side of the base unit  202  so as to mate with apertures  209  in the cover member  201 . In such an embodiment, the cover member  201  may exhibit elasticity to flex along its width sufficient to snap over and engage the tangs  207  on the base unit  202 , providing the advantage of being able to snap the base  202  and cover  201  together during installation in the field. As shown in  FIG. 7 , the tabs  207  are formed on respective upwardly projecting end posts  210 ,  212 , which are joined by parallel side rails  245 ,  246 , all integrally formed as part of the preferably unitary base or chassis  202 . 
         [0031]    Both the base  202  and cover  201  may be formed of die cast aluminum or other suitable metals or composites. The metals may include topical treatments to aid in heat dissipation such as anodizing, paints or other treatments that facilitate heat dissipation. Thermal plastics with metallic based fillers that aid in heat dissipation may be used. A mechanical fastener or fasteners such as screws or a mechanical snap device may also be used to hold the PC board in place onto the heat dissipating cover instead of thermal tape. The thermal tape (such as Berquest, 401 or 3M equivalent) acts to hold the PC board in place without mechanical fasteners and facilitates the transfer of heat to the heat dissipating cover. The alternative use of any coating or topical treatment such as grease, paste or oil that aids in dissipating heat from the PC Board to the heat dissipating base can be used. Illustrative dimensions for a fixture unit as shown in  FIG. 7  are circuit board width A′=1 inch, housing height B′=1.5 inches, and base length from one attachment hole center line to the other C′=12 inches or 6 inches. 
         [0032]    As may be further seen in  FIG. 7 , the cover member  201  includes an elongated platform  213 , which provides a mounting surface for a conformingly shaped thermal adhesive tape strip  215  and overlying circuit board  217 , which carries a serial array of LED&#39;s  219 . The tape  215  serves to attach the circuit board  217  to the platform  213 , while transferring heat from the LED&#39;s  219  to the heat sink arrangement  211 . Sufficient heat sinking is provided to remove the heat expected to be generated by the LEDs  219  based on their particular power (driving) requirements. Other means of attaching the circuit board  217  may be used, such as for example, rivets or threaded devices such as screws. 
         [0033]    The platform  213  of the cover member  201  further has respective radiused tongues  223 ,  224  at its opposite ends, whose respective lengths differ and are preferably selected as discussed above in connection with the embodiment of  FIGS. 1-6  so as to facilitate the positioning of LEDs  219  in adjacent, interconnected units so as to enhance the uniformity of illumination and avoid dark spots. Similarly, lower tongues  225 ,  226  extend from the base member and are dimensioned so as to facilitate attachment to adjacent units, also as discussed above. 
         [0034]      FIG. 8  illustrates an embodiment similar to that of  FIG. 9 . One particular difference is that the circuit board  231  of  FIG. 8  carries an array of groups  232  of three LED&#39;s. Each group includes a red, green and blue LED, thus facilitating generation of various colors of light. A suitable electrical conductor arrangement  234  is additionally provided to supply current to the respective LED drivers circuitry, e.g.  235 , located on internally positioned driver circuit board  236 . 
         [0035]      FIG. 9  illustrates a fixture component embodiment similar to that of  FIG. 7  but with some differences. In particular, the heat sink fins e.g.  341 , are disposed vertically on either side of the cover member  301 , and the driver circuitry e.g.  303 ,  305  for the LEDs  319  is disposed on the top LED-carrying surface of the PC board  317 . The PC board  317  may be fabricated of aluminum to further assist in heat transfer. Finally, the base or chassis  314 ,  302  has horizontally disposed feet  311  projecting perpendicularly from the side rail  345  and posts  314  on each side of the unit. In an illustrative embodiment, such feet may be ¼″ long each and extend ⅛″ from the edge of the overhanging cover member  301 . These feet  311  serve to maintain proper spacing from the side of a cove wherein the fixture components, e.g.  301 , may be mounted to facilitate downward installation of the cover member onto and over the chassis  302  by installers in the field and to contribute, in various applications, to better light uniformity, elimination of so-called “hot spots”, and improved thermal convection and heat dissipation. In some embodiments, holes could be provided in the feet to facilitate attachment of the unit in upright or inverted positions. 
         [0036]    Additionally, in the embodiment of  FIG. 9 , the cover member  301  is attached to the chassis  302  by bolts, screws or other suitable mechanically fasteners (not shown) inserted for example, through holes  304  ( FIG. 13 ) rather than by a snap-fit mechanism. In one embodiment, the cover  301  itself may be slightly tapered in inside cross-section such that it is slightly narrower at the bottom (dimension “D”) than at the top. 
         [0037]    Additionally, in  FIG. 9 , the aperture  350  in the circuit board  315  and cooperating aperture  355  in the cover  301  for introducing electrical leads  351  may be located at an outer edge  353 ,  356  ( FIG. 13 ) of the respective components  315 ,  301  rather than the center (e.g.  FIG. 7 ) or other position so as to enable the circuit board to be assembled first prior to attachment of the electrical connections and to simplify cutting of the circuit board out of aluminum. Thus, the electrical wiring may curve up and over the edge of the PC board, such that it is not necessary to provide a notch or other opening in the PC board. 
         [0038]      FIG. 10-12  illustrate an alternative embodiment similar to that of  FIG. 9  with the exception that red, green, and blue LEDs  391 ,  392 ,  393 , respectively, are employed with suitable electrical conductors and driving circuitry. As shown in  FIG. 11 , the A, B dimensioning of opposed tongues used in connection with the embodiment of  FIGS. 1-6  is utilized to more closely position the end-most LEDs  393   a ,  391   a  of adjacent fixtures  340 ,  380 . 
         [0039]    Various modifications may of course be made to the above disclosed embodiments in various other embodiments. For example, the plurality of LED light emitting diodes  143  is could be directly mounted on a heat sink in one embodiment. In another embodiment, the plurality of LED light emitting diodes  143  is mounted on a series of interchangeable circuit boards fixture. A plurality of interchangeable circuit boards offers various power ratings and brightness ratings, and each fixture has an associated heat exchange requirement for various application settings and designs. 
         [0040]    The heat sink  160 , in one embodiment, has a fixed heat exchange capability in ambient air. Other embodiments may provide a range of heat sink size choices so that higher power and lower power LED light emitting diodes can be substituted to customize the design and the environment in which the components will be applied. 
         [0041]    Various embodiments can prove advantageous in cove lighting applications where they can be concatenated and arranged to traverse various circuitous paths. In one embodiment, an oval design can be configured by choosing the proper component types and quantities to complete the oval shape as specified in particular lighting design requirements. Various embodiments may further include the advantageous wire harness interconnection and/or retention apparatus disclosed in U.S. provisional patent application Ser. No. 61/033,346, filed Mar. 3, 2008, incorporated in its entirety by reference herein. 
         [0042]      FIGS. 14 and 15  illustrate useful LED spacings which may be implemented in various embodiments.  FIG. 14  illustrates two adjacent 12″ (“D 1 ”) PC boards  451 ,  452 , each carrying 12 LED lamps equally spaced a distance D 2  of one inch apart from one another. The end-most LED&#39;s  453 ,  454 ,  455 ,  456  are each spaced a distance e.g. D 3  of ½ inch from the adjacent end of the respective board  451 ,  452  such that the opposite end-most lamps  454 ,  455  on adjacent boards  451 , 452  lie one inch apart, thus maintaining a one inch spacing across interconnected lamp fixture components. 
         [0043]      FIG. 15  illustrates a layout of LED lamps spaced a distance D 5  of two inches apart on adjacent 12 inch boards  458 ,  459 . Each board  458 ,  459  carries six LED lamps. The end-most lamps  461 ,  463  at the left end of each board  458 ,  459  is mounted a distance D 6  of ½ inch from that end, while the end-most lamps  462 ,  464  at the right-most ends are mounted a distance D 7  of 1.5 inches from those ends, thus resulting in the desired two inch spacing between the opposite end-most lamps  462 ,  463 . 
         [0044]    The invention has been described herein using specific embodiments for the purposes of illustration only. It will be readily apparent to one of ordinary skill in the art, however, that the principles of the invention can be embodied in other ways. Therefore, the invention should not be regarded as being limited in scope to the specific embodiments disclosed herein, but instead as being fully commensurate in scope with the following claims.