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CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional patent application Ser. No. 61/256,022, filed Oct. 29, 2009, which is incorporated herein by this reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention relates to a pivotable rail assembly for installing recessed lighting fixtures. 
       BACKGROUND 
       [0003]    Suspended mechanical ceilings (i.e., drop ceilings) typically include recessed lighting fixtures that are configured to be flush with the ceiling. These lighting fixtures, commonly referred to as troffer fixtures, are suspended from and secured in the ceiling by a “grid” of t-frames, which also suspend the ceiling tiles in the ceiling. 
         [0004]    Ceiling tiles are relatively thin and can be maneuvered into place and installed from below the ceiling. Troffer-type lighting fixtures, however, are comparatively thicker than ceiling tiles and cannot easily be maneuvered into place and installed from below the ceiling. Rather, these lighting fixtures have heretofore been maneuvered “above the grid” and dropped into position from above the ceiling. 
         [0005]    Installation work performed “above the grid” is not desirable. Because the lighting fixture must be maneuvered into place above the grid, the depth of the mechanical ceiling may need to be increased to allow adequate maneuvering space. Above the grid installations can also be complicated by nearby obstructions, such as plumbing and HVAC or electrical ducting. 
         [0006]    It would thus be desirable for a lighting fixture to be installable from “below the grid.” 
       SUMMARY 
       [0007]    A spring-loaded rail assembly for a lighting fixture that includes a rail that is pivotable downwardly as the fixture is inserted up through the ceiling grid opening to thereby create sufficient clearance for the fixture to be installed from “below the grid.” The spring tension biases the rail of the rail assembly back to its original, extended position once the fixture is above the grid, and the rail can rest on the ceiling grid to help support the fixture within the ceiling. 
         [0008]    The lighting fixture includes a lighting assembly and at least one pivotable rail assembly attached to the lighting assembly for securing the lighting assembly within a ceiling grid. In one embodiment, the at least one rail assembly includes least one mounting bracket, a rail and a spring. The rail is pivotable relative to the at least one mounting bracket. 
         [0009]    In certain embodiments the at least one mounting bracket and the rail are formed from sheet metal. In one embodiment, the spring is formed from music wire. 
         [0010]    In other embodiments, the at least one rail assembly includes two mounting brackets, and/or the lighting fixture includes two pivotable rail assemblies. 
         [0011]    In some embodiments, the at least one mounting bracket, rail and spring may be secured with a fastener, which can be a sheet metal screw. 
         [0012]    In yet other embodiments, the lighting assembly is further secured within the ceiling grid by at least one grid clip. 
         [0013]    In some embodiments, the lighting assembly is a fluorescent lighting assembly, a light-emitting diode light assembly or an incandescent lighting assembly. 
         [0014]    Methods for installing a lighting fixture within a ceiling grid are also provided. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1A  is a side view of a pivot bracket according to one embodiment of the invention. 
           [0016]      FIG. 1B  is an end view of a pivot bracket according to the embodiment of  FIG. 1A . 
           [0017]      FIG. 1C  is a top perspective view of a pivot bracket according to the embodiment of  FIG. 1A . 
           [0018]      FIG. 2A  is a top perspective view of a portion of a flange rail according to one embodiment of the invention. 
           [0019]      FIG. 2B  is an end view of a flange rail according to the embodiment of  FIG. 2A . 
           [0020]      FIG. 2C  is a top view of a flange rail according to the embodiment of  FIG. 2A . 
           [0021]      FIG. 3A  is a top perspective view of a spring according to one embodiment of the invention. 
           [0022]      FIG. 3B  is a side view of a spring according to the embodiment of  FIG. 3A . 
           [0023]      FIG. 3C  is an end view of a spring according to the embodiment of  FIG. 3A . 
           [0024]      FIG. 4  is an end view of a flange rail assembly according to one embodiment of the invention. 
           [0025]      FIG. 5A  is a top view of a flange rail assembly according to an embodiment of the invention. 
           [0026]      FIG. 5B  is a side view of the flange rail assembly according to the embodiment of  FIG. 5A . 
           [0027]      FIG. 6A  is an end view of a lighting fixture according to one embodiment of the invention. 
           [0028]      FIG. 6B  is a side view of a lighting fixture according to an embodiment of the invention. 
           [0029]      FIG. 6C  is an end view of a portion of a lighting fixture according to one embodiment of the invention. 
           [0030]      FIG. 6D  is a side view of a lighting fixture according to an embodiment of the invention. 
           [0031]      FIG. 7  is an end view of a flange rail assembly according to an embodiment of the invention. 
           [0032]      FIG. 8  is a top perspective view of a grid clip according to one embodiment of the invention. 
           [0033]      FIG. 9  is a top perspective view of a portion of a lighting fixture with grid clips according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    One embodiment of the invention includes a spring-loaded rail assembly  10  for a lighting fixture that includes a rail that is pivotable downwardly as the fixture is inserted up through the ceiling grid opening to thereby create sufficient clearance for the fixture to be installed from “below the grid.” The spring tension biases the rail of the rail assembly  10  back to its original, extended position once the fixture is above the grid, and the rail can rest on the ceiling grid to help support the fixture within the ceiling. 
         [0035]    With reference to  FIGS. 1A-5 , the rail assembly  10  includes a mounting bracket  100 , a rail  200  and spring  300 , which are held together and in place by a pivot screw  500 , as discussed below. Spring  300  is tensioned to hold rail  200  in the illustrated, extended position when at rest (i.e., when no external forces are being applied to the rail  200 ). Several views of an exemplary mounting bracket  100  are provided in  FIGS. 1A-1C , views of an exemplary rail  200  are provided in  FIGS. 2A-2C , and views of an exemplary spring  300  are provided in  FIGS. 3A-3C .  FIGS. 4 ,  5 A and  5 B show mounting bracket  100  attached to rail  200  with spring  300  and pivot screw  500 . 
         [0036]    Mounting bracket  100  and rail  200  can be formed from suitable materials for use in lighting fixture applications, including but not limited to aluminum and other metals and their alloys and plastic. Pivot screw  500  can be formed from suitable fastener materials, such as aluminum and/or steel and their alloys. In one embodiment, pivot screw  500  is a sheet metal screw. Spring  300  can be formed from suitable torsion coil spring materials including but not limited to steel alloys (such as carbon alloys, chrome silicon, chrome vanadium, and stainless steel), beryllium copper alloy, phosphor bronze, and titanium. In one embodiment, the spring is formed from high carbon steel (e.g., music wire). 
         [0037]    In one embodiment, a rail assembly  10  is affixed to a side of a lighting fixture by attaching a pair of mounting brackets  100  to the outside of the fixture with a fastener such as a screw inserted through one or more mounting holes  110  in the mounting bracket  100 . Each end of a rail  200  is attached to the one of the mounting brackets  100  with a spring  300  and pivot screw  500 . The mounting bracket  100  has a screw hole  120 , and each end of the rail  200  has a screw hole  210  for receiving the pivot screw  500  and holding the spring  300  in place. To assemble the rail assembly  10 , the pivot screw  500  is inserted into the screw hole  120  in the mounting bracket  100 . A spring  300  is inserted over the pivot screw  500  through a central aperture  310  of the spring  300 . The screw hole  210  on the rail  200  is lined up with the pivot screw  500 , and the pivot screw  500  is securely fastened into the screw hole  210  on the rail  200 . In this manner, as illustrated in  FIGS. 5A and 5B , the spring  300  is secured between the screw hole  120  in the mounting bracket  100  and the screw hole  210  in the rail  200 . 
         [0038]    The spring  300  has two ends  320 ,  330  and is configured such that one of the ends (e.g.,  320 ) is biased against the mounting bracket  100  and the other end (e.g.,  330 ) is biased against the rail  200 . The spring  300  is thus configured such that manually rotating the rail  200  about the pivot screw  500  compresses the spring  300 , and releasing the spring  300  relaxes the compression of the spring  300 , causing the rail  200  to rotate back into its original position. It will be understood that if a rail  200  includes two mounting brackets  100  (one on each end of the rail  200 ), it may be desirable or necessary to provide mounting brackets  100  and springs  300  that are mirror images of each other, as a clockwise rotation of the rail  200  on one side of the rail assembly  10  corresponds to a counterclockwise rotation of the rail  200  on the other side of the rail assembly  10 . Moreover, while the rail assembly  10  is described as having a pivot screw  500 , it will be recognized that other types of fasteners, such as a nut and bolt, could be used to connect the mounting bracket  100 , rail  200  and spring  300 . 
         [0039]    The spring  300  is configured and arranged in the rail assembly  10  to bias rail  200  in the extended position illustrated in  FIG. 4  (i.e., with flange  220  of the rail  200  extending generally outwardly from the rail assembly  10 ) so that the flange  220  of the rail  200  can rest on the t-frame of the ceiling grid to thereby support the lighting fixture within the ceiling grid. When the flange  220  of the rail  200  is manually rotated downwardly (so that the assembly  10  will fit between the t-frames of the ceiling grid, as described below), the spring  300  is placed under tension. 
         [0040]    To describe the operation of the rail assembly  10  in more detail, when the lighting fixture having at least one rail assembly  10  mounted thereon is to be installed, the flange  220  of the flange rail  200  is rotated downwardly. The downward rotation of the flange  220  provides sufficient clearance for the lighting fixture to be inserted into the ceiling grid. When the lighting fixture has cleared the ceiling grid, the flange  220  is released. The spring  300  causes the flange  220  to rotate back into its “resting” position. The lighting fixture is thus held in place at least in part by engagement of the flange  220  with the t-frame of the ceiling grid. With reference to  FIGS. 2A ,  2 B,  4  and  7 , it will be evident that a portion  225  of flange  220  extends downwardly from the flange  220  when the flange  220  is in its resting position. The length of this portion  225  determines the position of the light fixture relative to the face of the ceiling (since the fixture rests on the t-frame of the ceiling grid on this portion  225 ), and it will be recognized that the length of this portion  225  can be adjusted for different configurations. 
         [0041]    Embodiments of this operation are illustrated in exemplary  FIGS. 6A-6D .  FIG. 6A  illustrates an end view of a lighting fixture having two rail assemblies  10  attached at opposite ends of a lighting fixture  600  (installed parallel to the lamps).  FIG. 6B  illustrates a side view of this fixture.  FIG. 6C  shows the fixture with the flange  220  of one rail  200  in its extended position  640  and the flange  220  of the other rail  200  in is depressed position  650 .  FIG. 6D  shows the lighting fixture installed in the ceiling grid. As illustrated in  FIGS. 6A and 6B , with both rail assemblies  10  in their depressed positions, the lighting fixture can be installed by tilting the fixture into the grid and adjusting the fixture so that the flanges  220  of the rails  200  are above the t-frame of the ceiling grid  610 . With the fixture slightly raised above the t-frame  610 , the flanges  220  are then released so that they pivot back to their extended positions by action of the spring  300  and can rest on the t-frame  610  to help retain the fixture within the ceiling. 
         [0042]    Although the lighting fixture is described above as having two rail assemblies  10  installed thereon (on opposite sides of the fixture), it will be understood that only one rail assembly  10  or more than two rail assemblies  10  could be installed on the fixture. In addition, the rail assembly on one side of the fixture could be split into two or more components if desired for ease of machining or for other considerations. In other words, two separate rail assemblies could be installed on one side (or more than one side) of the lighting fixture. 
         [0043]    An alternative embodiment of a mounting bracket  710  is illustrated in  FIG. 7 . 
         [0044]    The rails  200  and other components of the rail assembly  10  described herein can be sized for different types of grid constructions, such as “slot grid” or “inverted T-grid” constructions. It will be understood by a person skilled in the art that the rail and other components of the embodiments described herein can be appropriately sized and shaped for other types of grid constructions. 
         [0045]    In certain embodiments, it may be desirable to secure the lighting fixture to the ceiling grid with one or more grid clips to more securely hold the lighting fixture in place. Such a configuration is particularly desirable—and in fact may be required such as by local building codes—in geographical areas prone to earthquakes. Accordingly, if desired one or more grid clips  810  as shown in  FIG. 8  may be provided. The grid clip  810  may be packaged with the lighting fixture. The grid clips  810  are removed from the fixture prior to installation and then manually installed after installation of the fixture in the ceiling grid. The clips can be manually formed by bending each clip at  820  and  830 , inserting one end of the clip  810  into slots in the lighting fixture (see  FIG. 9 ), and then affixing the clip to the ceiling grid with a fastener. Wings  840  may be bent upward to prevent the grid clip  810  from separating from the lighting fixture. Obviously, other configurations of grid clips  810  would be known to one of skill in the art and within the scope of this disclosure. 
         [0046]    An exemplary lighting fixture for use with embodiments of the invention as described herein is a fluorescent lighting troffer. Alternative lighting fixture designs include light emitting diode (LED) fixtures and incandescent fixtures. 
         [0047]    The embodiments described herein allow a lighting fixture to be installed from below the ceiling, which may also allow for decreased ceiling depth since the need for maneuvering room above the ceiling grid is eliminated. In addition, fixtures equipped with embodiments of the invention described herein can be installed anywhere that ceiling obstructions complicate or prevent traditional “above the grid” fixture installations. 
         [0048]    The foregoing is provided for the purpose of illustrating, explaining and describing embodiments of the present invention. Further modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the spirit of the invention or the scope of the claims. Moreover, all aspects of the invention need not necessarily be practiced in every embodiment of the invention.

Summary:
A lighting fixture for installation in a ceiling grid includes a lighting assembly and at least one pivotable rail assembly attached to the lighting assembly. The rail assembly includes at least one mounting bracket, a rail and a spring. The rail is pivotable relative to the at least one mounting bracket. To insert the lighting fixture into the ceiling grid, the rail is rotated relative to the mounting bracket such that the rail will clear the ceiling grid, thereby compressing the spring. The lighting fixture is inserted into the ceiling grid and the rail is released. The compression of the spring is relaxed, and the rail rotates back into its original position. The rail, now extending beyond the boundary of the ceiling grid, rests on the ceiling grid is thereby secured within the ceiling grid.