Patent Publication Number: US-7909499-B2

Title: LED track lighting module

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to track lighting and, more particularly, to a track lighting module containing a light-emitting diode (“LED”) for use with a low-voltage track as a power supply. 
     BACKGROUND OF THE INVENTION 
     As LED lighting becomes more prevalent, there is an increasing need for track lighting systems that can be efficiently manufactured at a low cost, and also can be easily and quickly installed in a manner that provides reliable operation over years of operation. 
     SUMMARY OF THE INVENTION 
     One embodiment provides a track light module for use with a low-voltage track carrying a pair of elongated conductors transversely spaced from each other and accessible through a longitudinal slot in the track. The module comprises a first housing containing a printed circuit board that carries an LED and forming an aperture permitting light from the LED to be radiated beyond the first housing. A second housing carries a pair of electrical conductors adapted to extend into the low-voltage track to make contact with the conductors within the track. The second housing also includes surfaces for fastening the second housing to the track when the second housing and the track are moved relative to each other. A pair of electrical contacts on the printed circuit board contact the conductors carried by the second housing and thereby receive electrical power for the LED. A connector attaches the first and second housings together. 
     When installed on a track, the resulting track lighting assembly comprises a low-voltage track carrying a pair of elongated conductors transversely spaced from each other and accessible through a longitudinal slot in the track, and a light module including a first housing that contains a printed circuit board carrying an LED and forms an aperture permitting light from the LED to be radiated beyond the second housing. A second housing carries a pair of electrical conductors adapted to extend into the low-voltage track to make contact with the conductors within the track. The second housing also includes surfaces for fastening the second housing to the track when the second housing and the track are moved relative to each other. A pair of electrical contacts on the printed circuit board contact the conductors carried by the second housing and thereby receive electrical power for the LED. A connector attaches the first and second housings. 
     This invention permits the light module to be quickly and easily assembled from a small number of parts that simply snap together so that no separate fastening devices are required. Thus, the light module can be efficiently manufactured in large numbers at a low cost. The final assembly has good structural integrity which is maintained over a long operating life. 
     The foregoing and additional aspects of the present invention will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments, which is made with reference to the drawings, a brief description of which is provided next. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings. 
         FIG. 1  is a top perspective view of a track light module adapted to be mounted on track carrying power conductors. 
         FIG. 2  is an exploded top perspective view of the light module shown in  FIG. 1  and a track on which the light module can be mounted, with the second housing of the light module sectioned to show the internal structure. 
         FIG. 3  is an enlarged top plan view of the light module shown in  FIG. 1 . 
         FIG. 4  is a sectional view taken along line  4 - 4  in  FIG. 3 . 
         FIG. 4A  is a top plan view of the sub-assembly of elements  23  and  28  shown in  FIG. 4 . 
         FIG. 5  is a sectional view taken along line  5 - 5  in  FIG. 3 . 
         FIG. 6A  is a sectional view taken along line  6 A- 6 A in  FIG. 3 , with the connector detached from the housing. 
         FIG. 6B  is the same sectional view shown in  FIG. 6A , with the connector attached to the housing. 
         FIG. 7  is an enlarged top perspective of one of the right-hand portion (the second housing of the light module) of the assembly shown in  FIG. 1 , with a portion cut away to show the internal structure. 
         FIG. 8  is an enlargement of the lower portion of the second housing shown in  FIG. 7 . 
     
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     Although the invention will be described in connection with certain preferred embodiments, it will be understood that the invention is not limited to those particular embodiments. On the contrary, the invention is intended to cover all alternatives, modifications, and equivalent arrangements as may be included within the spirit and scope of the invention as defined by the appended claims. 
     Turning now to the drawings, a conventional low-voltage track  10  ( FIGS. 2 and 5 ) includes a pair of elongated conductors  11  and  12  connected to a transformer that converts 120-volt AC power to a suitable low-voltage power to be distributed by the track  10 , such as 12-volt AC power. The track housing  13  is a plastic extrusion having a generally rectangular transverse cross-section forming a hollow interior  14  that is open at both ends and through a longitudinal slot  15  in the top wall of the housing  13 . The conductors  11  and  12  extend along the length of the track  10  and are held in place by a pair of curved flanges  16  and  17  that terminate above the bottom wall  18  of the track  10 , to allow access to the conductors at any point along the length of the track  10 . This permits light modules to be connected to the conductors  11  and  12  at any desired location along the track  10 . 
       FIGS. 1-8  depict a light module  20  adapted to be mounted on the track  10  so that power from the conductors  11  and  12  illuminates a light-emitting diode (LED) (or LED cluster) mounted beneath a translucent lens  21  on a small printed circuit board (PCB)  22 . As used herein, the term “LED” includes a cluster of light-emitting diodes. The PCB  22  is surrounded by a first housing formed by a sleeve  23  that has an open end  24  for receiving the PCB  22 , and a top aperture  25  through which the lens  21  protrudes when the PCB  22  is in place inside the sleeve  23 . The lens  21  is preferably coated on its inside surface with a phosphor to help achieve a desired color temperature of light (e.g., 3000K or 5000K) and diffuse the light emitted for more even distribution. 
     As can be seen in  FIGS. 2 and 4 , one end of the sleeve  23  forms a tab  26  for the first housing having a slot  27  for receiving an orthogonal tab  28  on the PCB  22 . The portions of the orthogonal tab  28  that project laterally from opposite sides of the slot  27  carry conductors  29  and  30  (see  FIG. 2 ) on both the top and bottom surfaces of the orthogonal tab  28 . The orthogonal tab  28  may therefore also be referred to below as the conductor tab  28  to distinguish it from the first housing tab  26 . As will be described below, the conductors  29  and  30  serve as the power input terminals for the PCB  22 , and are connected to other conductors formed on the PCB  22  to supply power to the LED  21  via conventional circuitry on the PCB  22 , including a driver for the LED. A heat sink  22 a attached to the PCB  22  directly adjacent the LED  21  dissipates heat via the interior space and open ends of the sleeve  23 . PCB&#39;s of this type are commercially available, e.g., from Lynk Labs Inc. in Elgin, Ill. 
     The conductors  29  and  30  on the PCB conductor tab  28  are engaged by a pair of conductive spring contacts  31  and  32  captured inside a non-conductive second housing  33 . The spring contacts  31  and  32  ( FIG. 2 ) include integral L-shaped legs  34  and  35  that extend downwardly through an opening in the bottom wall of the second housing  33 . When the LED module  20  is attached to the track  10 , the lower ends of the legs  34  and  35  make contact with the track conductors  11  and  12 . Power can then be supplied from the conductors  11  and  12  through the contacts  31  and  32  to the conductors  29  and  30  on the PCB  22 , and then through the circuitry on the PCB to the LED. 
     The second housing  33  also receives a connector  36  that fits between the two conductive legs  34  and  35  to hold the two spring contacts  31  and  32  in desired positions within the second housing  33 . The connector  36  fits into the open lower end of the second housing  33 , and is held in place within the second housing  33  by detents formed by mating ribs  36 a and grooves  33 a formed by opposed surfaces of the connector  36  and the second housing  33  (see  FIGS. 6A and 6B ). Referring especially to  FIG. 4 , a cantilevered arm  37  formed by the connector  36  extends along the lower surface of the first housing tab  26 , and the top surface of the arm  37  forms a groove  38  that receives a rib  39  depending from the bottom surface of the first housing tab  26 . It will be appreciated that the combination of the detents that lock the connector  36  to the second housing  33 , and the interlocking groove  38  and rib  39 , effectively locks together the second housing  33  and the sleeve, or first housing  23  thereby forming a light module  20  that can be handled as a single unit during installation on the track  10 . 
     The lower portion of the second housing  33  forms two pairs of vertically spaced flanges  40  and  41  on opposite sides of the housing ( FIGS. 5 ,  7  and  8 ). The space between the two flanges  40  and  41  in each pair is dimensioned to receive portions of the top wall of the track housing  13  when the light module  20  is attached to the track  10 , as shown in  FIG. 5 . When the module  20  is rotated 90° (around a vertical axis) from the position shown in  FIG. 2 , the lower flanges  41  are narrow enough to fit through the longitudinal slot  15  of the track  10 , with the lower surfaces of the upper flanges resting on the top surface of the track  10  on opposite sides of the slot  15 . Then as the module is rotated to the position shown in  FIG. 2  (as well as  FIGS. 3-5 ), the lower flanges  41  slide under the top wall of the track housing  13 , thereby fastening the light module  20  to the track  10 . Chamfered surfaces  41  a and  41 b on the top surfaces of the flanges  41  facilitate smooth sliding engagement of the flanges  41  with the lower surface of the top wall of the track  10  (on both sides of the slot  15 ) during rotation of the second housing  33  relative to the track  10 . Similarly, curved end surfaces  41   c  on the flanges  41  facilitate smooth sliding engagement of the ends of the flanges  41  with the side walls of the track  10  during rotation of the second housing  33  relative to the track  10 . 
     The rotational movement of the module  20  during installation on the track  10  brings the bent lower ends of the legs  34  and  35  of the spring contacts  31  and  32  into firm contact with the track conductors  11  and  12 . The free ends of the bent lower ends of the legs  34  and  35  are preferably curved (see  FIG. 2 ) so that they act as cam surfaces as the rotational movement of the module  20  brings those ends of the legs  34  and  35  into engagement with the conductors  11  and  12 . As can be seen in  FIG. 5 , the ends of the legs  34  and  35  engage the respective conductors  11  and  12  slightly below the middle of those conductors, to ensure good electrical contact. 
     While the present invention has been described with reference to one or more particular embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the present invention. Each of these embodiments and obvious variations thereof is contemplated as falling within the spirit and scope of the claimed invention, which is set forth in the following claims.