Abstract:
A stair rail light attachable between first and second vertical stair rail posts and having an elongated central housing whose interior mounts an extrusion designed to hold and position a plurality of LED carrier members wherein the housing slidably engages respective mounting plugs pivotally attached to respective stair rail posts, thereby permitting the length of the rail light to be adjusted in the field.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the Paris Convention priority of U.S. Provisional Application No. 61/104,604 entitled “Rail Light,” filed Oct. 10, 2008, the contents of which are hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The subject disclosure relates to the field of electrical lighting apparatus and light fixtures, and more particularly to a field installable stair rail light. 
         [0004]    2. Related Art 
         [0005]    Various lighting systems have been devised for theaters and other venues for lighting aisles, stairs and the like. Low voltage lighting systems have been used which incorporate LED light strips in the case of steps and stairs. Such strips have been provided at the edge or “nose” of each stair such that the edge of each step is illuminated and visible to someone walking up or down the stairway. 
       SUMMARY 
       [0006]    The following is a summary of various aspects and advantages realizable according to various embodiments of the invention. It is provided as an introduction to assist those skilled in the art to more rapidly assimilate the detailed discussion which ensues and does not and is not intended in any way to limit the scope of the claims which are appended hereto in order to particularly point out the invention. 
         [0007]    According to an illustrative embodiment, a stair rail light is provided which may be attached between first and second vertical stair rail posts to direct illumination from either side of the light fixture onto the surrounding aisle-way beneath the light. The rail light of the illustrative embodiment comprises an elongated central housing whose interior mounts an extrusion designed to hold and position a plurality of LED carrier members. Each end of the housing slidably engages an end plug component, which is pivotally attached to the stair rail. The slidable engagement between the housing and respective end plugs permits the length of the rail light to be adjusted in the field. 
         [0008]    In one embodiment, the housing has a plurality of axially-running projections on an inside surface thereof and respective inwardly projecting lips along respective lower edges. Each end plug in turn has an outer surface which includes a plurality of axially-running grooves each positioned to slidably receive and mate with a respective one of the axially-running interior projections of the housing and recesses formed respectively along first and second lower edges thereof, which are sized and dimensioned to slidably receive and mate with a respective one of the inwardly projecting lips on the lower edges of the housing. 
         [0009]    In such an embodiment, the slidable mating of the axially-running grooves with the axially-running projections and the slidable engagement of the first and second lower edges with the first and second recesses provides the adjustability which permits the length of the light fixture to be adjusted in the field to adapt to varying dimensional requirements; i.e. varying distances between opposing vertical stair rail portions to which the light is attached. 
         [0010]    In one embodiment, the extrusion may be so shaped and dimensioned that it snap-fits into the housing, and may include a plurality of interior projections disposed to position and retain the LED carrier members. In one embodiment, the plurality of interior projections comprise a centrally positioned depending projection and first and second depending projections positioned on either side of said centrally depending projection, each of the first and second depending projections having an end shaped to retain an edge of one of the LED carrier members. In such an embodiment, each said LED carrier member may comprise a flat LED mounting surface and a channel of Y-shaped cross-section wherein the channel engages the end of the depending central projection of the extrusion. 
         [0011]    In one illustrative embodiment, the light fixture apparatus may further comprise first and second pivot plates for pivotally attaching a respective one of said end plugs to a stair rail post, each pivot plate including a front surface having a plurality of mounting holes, a circular opening for passing an electrical cable, and first and second tabs projecting therefrom for receiving a pivot pin for pivotally attaches an end plug to its respective pivot plate. Each pivot plate may further comprise an inner adapter plate positioned behind its front surface to strengthen the structure. 
     
    
     
       DRAWINGS 
         [0012]    The features of the present disclosure will become more apparent with reference to the following description taken in conjunction with the accompanying drawings wherein like reference numerals denote like elements and in which: 
           [0013]      FIG. 1  is front perspective view of an illustrative rail light embodiment mounted on a stair rail; 
           [0014]      FIG. 2  is a perspective view of the underside of the rail light of  FIG. 1 ; 
           [0015]      FIG. 3  is a perspective view illustrating an end plug and pivot plate according to an illustrative embodiment; 
           [0016]      FIG. 4  is a cross-sectional view of the rail light embodiment taken at  4 - 4  of  FIG. 1 ; 
           [0017]      FIG. 5  is a perspective exploded fragmentary view illustrating selected components of the illustrative rail light embodiment; 
           [0018]      FIG. 6  is a top view of an end plug according to an illustrative embodiment; 
           [0019]      FIG. 7  is an end view of the end plug of  FIG. 6 ; 
           [0020]      FIG. 8  is a side view of the end plug of  FIG. 6 ; 
           [0021]      FIG. 9  is perspective view of the underside of the end plug of  FIG. 6 ; 
           [0022]      FIG. 10  is a sectional view of the end plug taken at  10 - 10  of  FIG. 8 ; 
           [0023]      FIG. 11  is a sectional view of the end plug taken at  11 - 11  of  FIG. 8 ; 
           [0024]      FIG. 12  is a sectional view of the end plug taken at  12 - 12  of  FIG. 6 ; 
           [0025]      FIG. 13  is a top view of a pivot plate according to an illustrative embodiment; 
           [0026]      FIG. 14  is an end view of the pivot plate of  FIG. 13 ; 
           [0027]      FIG. 15  is a side view of the pivot plate of  FIG. 13 ; 
           [0028]      FIG. 16  is a bottom view of the pivot plate of  FIG. 13 ; 
           [0029]      FIG. 17  is a perspective view of the underside of the pivot plate of  FIG. 13 ; 
           [0030]      FIG. 18  is a sectional view of the pivot plate of  FIG. 13  taken at  18 - 18  of  FIG. 13 ; 
           [0031]      FIG. 19  is a sectional view of the pivot plate of  FIG. 13  taken at  19 - 19  of  FIG. 13 ; and 
           [0032]      FIG. 20  is a partial perspective view of a portion of the underside of an illustrative embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]      FIG. 1  shows a rail light  11  according to an illustrative embodiment mounted between vertical pole portion  14 ,  16  of a free standing stair rail  13 . Such a free standing stair rail  13  may be installed, for example, in the middle of descending aisle way. 
         [0034]    The rail light  11  of the illustrative embodiment includes an elongated outer housing  15 , which attaches at its respective ends  17 ,  19  to respective mounting brackets  21 ,  23 . The housing  15  and mounting brackets  21 , 23  are preferably fabricated of die cast aluminum for strength but could be fabricated of plastic, other metals or composites in various embodiments. 
         [0035]    As may be seen in  FIG. 2 , the housing  15  has an inner extrusion  25  mounted therein which is designed to pop into and be retained by the housing  15 , as will be discussed in further detail below. The inner extrusion  25  in turn snug-fittingly receives a number of lampholder units or carriers, e.g.  27 , which in the illustrative embodiment comprise a number of LED lamps  33  and associated components. One set of LED carriers  27  is angled to direct light to the left of the stair light  11 , while a second set is angled to direct light to the right of the light  11 . 
         [0036]    As illustrated in  FIG. 3 , each mounting bracket  21 ,  23  of the illustrative embodiment includes a pivot plate  37  attached to one of the stair rails  5 , e.g.  14 . A rail support end plug  39  is pivotally attached to the pivot plate  37 . The end plug  39  has three parallel, axially-running grooves  41 ,  43 ,  45  on its outer upper surface, which slidably receive mating projections  47 ,  49 ,  51  formed on the interior  53  of the housing  15  ( FIG. 4 ). In the illustrative embodiment, these projections  47 ,  49 ,  51  run lengthwise (axially) in parallel and extend the entire length of the housing  15 . 
         [0037]    The end plug  39  further has respective recesses  53 ,  55  formed along each of its respective lower edges or ends  57 ,  59 . These recesses  53 ,  55  are captured by respective cooperating lips  61 ,  63  formed on respective lower edges or ends  62 ,  64  of the housing  15  ( FIG. 4 ) to thereby slidably position the housing  15  within the end plug  39 . 
         [0038]    As may be appreciated, the housing  15  telescopically slides with respect to the end plug  39 , thereby providing adjustability when installing the rail light  11  to stair rail posts or other surfaces, e.g.  14 ,  16  in the field. Threaded screw holes  58  are formed in the end plug  39  to receive set screws or other devices for fixing the housing  15  in position once proper positioning is achieved during installation. Representative dimensions of an illustrative embodiment if the housing  15  are A=1.06 inches, B=1.10 inches. 
         [0039]    The construction of the housing  15 , extrusion  23  and lamp carriers  27  is further illustrated in  FIGS. 4 and 5 . As shown, the extrusion  23  has outer side surfaces  65 ,  67 , and two upper surfaces  69 ,  71 , which engage the interior surface of the housing  15 . The outer side surfaces  65 ,  67  are flexible and of such stiffness that the extrusion  23  snap-fits vertically into the housing, preferably such that it cannot be removed by hand (i.e. without a tool.) 
         [0040]    A central projection  73  with an end  75  of bulbous cross-section depends from the center of the inner surface of the extrusion  23 . Symmetrically formed, downwardly projecting interior surfaces  77 ,  79  also depend from the inner surface of the extrusion  23  on either side of the central projection  73  and terminate in grooved ends  81 ,  83 , which ends  81 ,  83  appear “hook-shaped” in cross-section. The inner extrusion  23  is preferably formed of a suitable plastic. 
         [0041]    As further illustrated, the grooves  85 ,  87  in ends  81 ,  83  of the interior surfaces  77 ,  79 , slidably receive respective edges  89 ,  91  of LED carriers  93 ,  95 , each of which includes a planar rectangular portion  94 ,  96 , terminating at one end in channels  97 ,  99  of “Y-shaped” cross-section. These channels  97 ,  99  slidably receive the bulbous end  75  of the central extrusion projection  73 . 
         [0042]    Respective electrical conductor pairs  105 ,  107  run through the interior of the inner extrusion  23  and are attached to the respective LED carriers, e.g.  93 ,  95 , which may be fabricated of a suitable plastic. In the illustrative embodiment, the carriers  93 ,  95  are positioned with the respective planes of their LED mounting surfaces  94 ,  96  at an angle θ of, for example, 20 degrees to the vertical, resulting in oppositely directed LED light beams well-positioned to illuminate step surfaces on either side of the rail light  11 . 
         [0043]      FIGS. 6 to 12  illustrate the rail support end plug  39  in further detail. The plug  39  includes a rear passageway  105 , which leads from the underside of attachment tab  107  into the interior  109  of the plug  39  and provides for passage of an electrical power cable. As noted above, threaded openings  58  on the underside of the end plug  39  receive suitable set screws to fix the housing  15  in position. The interior  109  of the plug  39  is tapered from a wider width at the front opening  108  to a narrower width at the rear end  110  as shown in  FIG. 12  to facilitate removal from a mold. Core relief cut-outs  111  are formed on the underside of the plug  39  to reduce the amount of material required to form the part and to speed-up the molding process. A cylindrical opening  108  is formed in the tab  107  to receive a pivot pin  122  ( FIG. 3 ). 
         [0044]      FIGS. 13 to 19  illustrate further details of the pivot plate  37 . The plate  37  has a front surface  120  which includes two mounting holes  115 , as well as a circular opening  117 , which passes the electrical power cable. Respective mounting tangs  119 ,  121  extend above the front surface  120  to receive a suitable pivot pin, bolt or other device  122  ( FIG. 3 ) for pivotally interconnecting the plug  39  to the plate  37 . The bottom surface  123  of the plate is arcuately curved in cross-section to better conform to the contour of a rail, e.g.  14 , to which the plate  37  is attached. 
         [0045]    As may be seen in  FIGS. 16 and 17  an inner adapter plate  131  is positioned on the underside of the plate  37  in order to strengthen the structure and prevent damage from over-tightening of screws inserted into openings  115  to attach the pivot plate  37  to a stair rail or other surface. In the illustrative embodiment, the inner adapter plate  131  and pivot plate  37  are molded as a single, unitary part, but could be separate parts in other embodiments. In other embodiments the inner adapter plate  131  could be omitted. 
         [0046]    In the illustrative embodiment, each carrier, e.g.  93 ,  95 , mounts two LEDs and their associated driver circuitry, with the LEDs  33  being sized from, for example, ¼ to 1 watt. Suitable lenses may be applied to the LEDs  33  as desired. A water tight, transparent cover may be provided over the opening in the underside of the housing  15  to transmit light to a stairway while shielding the LEDs  33  from the elements. Such a cover may also comprise an optical lens. Clamping attachment of the plugs  39  to a stair rail or other surface could also be employed in place of the pivot plates  37 . The plates  37  and plugs  39  may each be molded from A 380.0-F die casting aluminum alloy or other suitable materials. 
         [0047]      FIG. 20  shows an illustrative configuration of the underside of the rail light  11 . As may be seen in this view, a snap-fit plastic cover  141  is insertable into the housing to cover electrical interconnections  143 ,  145 , which emanate from a power cable  147 . The cover  141  also positions the left-most LED carrier  27  in the channel provided by the extrusion  23 . A plastic spacer  148  may be shaped to have the same cross-section as the carrier members  94 ,  95  shown in  FIG. 4  and therefore may be inserted into the extrusion  23  in the same manner as the carriers  27 . The spacer  148  spaces one LED carrier  27  a selected distance apart from an adjacent LED carrier  27 . Such spacers  148  are inserted as desired between adjacent carrier pairs  27  down the length of the extrusion  23 , on each side thereof, in an illustrative embodiment. 
         [0048]    Those skilled in the art will appreciate that various adaptations and modifications of the just described embodiments can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.