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CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Application No. 60/894,416, filed Mar. 12, 2007, whose entire contents are hereby incorporated by reference. 
    
    
     BACKGROUND 
     Recessed lighting fixtures are commonplace in residential homes and commercial buildings. A recessed lighting fixture typically has a metal housing or can, an electrical junction box, and a conical-shaped recessed trim piece to direct and reflect the lighting emitted by a bulb that is in a bulb holder or socket. The recessed lighting can is installed above the ceiling in a building or house so that the opening in the can and trim are flush with the ceiling. The light is recessed into the ceiling. 
     The can with a junction box and other hardware are suspended by a pair of hanger bars extending parallel and on opposite sides of the assembly. The hanger bar is typically stamped from steel and is length-adjustable by a telescopic action. The opposite ends of the hanger bar, which resemble ears, are configured to attach to the ceiling support structure. 
     Specifically, one type of standard ceiling is supported by joists, and the recessed lighting fixture is mounted onto the joists via the hanger bars. When the joists are made of wood or concrete, for example, the hanger bars are usually mounted to the joists with nails, screws or other standard mounting means. The weight of the light fixture is thereby supported by the joists through the hanger bars. 
     Alternatively, the ceiling may be of the “drop down” or suspended type. A drop down ceiling is a secondary ceiling often formed to conceal piping, wiring, HVAC, and/or the floor above. The drop down ceiling typically consists of a grid-work of metal channels in the shape of an upside-down “T,” suspended on wires from an overhead structure. The channels snap together in a regularly spaced pattern, and the resulting cells are filled with lightweight “acoustic ceiling tiles” or “panels” dropped into the grid. Light fixtures may be installed into the grid as desired. 
     The hanger bars of light fixtures sometimes include a clamp or adapter formed into the hanger bar to attach to the T-bars of a drop down ceiling. These clamps or adapters are sometimes an unnecessary appendage. For example, when installing a light fixture onto a joist of a standard ceiling rather than onto a drop down ceiling, the installer may choose to use a nail or other fastner to secure the assembly in place on the joist. The clamps or adapters are then unnecessary and may even get in the way during installation. Since they are formed as part of the hanger bar, they cannot be removed or detached. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a hanger bar used to support a recessed lighting fixture or assembly. 
     In one embodiment of the invention, a hanger bar assembly for recessed lighting fixtures has a first bar that has a channel. A second bar is disposed within the channel, and the second bar moves within the channel for a telescoping action. There is a first bracket on an end of the first bar, and a second bracket on an end of the second bar. A first spring clip is detachably coupled to the first bracket, and a second spring clip is detachably coupled to the second bracket. Each of the first and second clips has a pair of downwardly extending arms. A first leg extends from the first spring arm, a second leg extends from the second spring arm, and a foot extends outwardly from the second leg. The clip also has a third arm for removably attaching the clip to a respective bracket. Each of the brackets has a nail holder and a nail extending through the nail holder. The nail holder may be an opening in the bracket. 
     The nails may each extend at an angle relative to the first and second bars so that the nail shaft is angled away from the hanger bars, or downward below the hanger bars, or both. By angling the nail away from the hanger bar, it is easier for the installer to use a hammer to drive the nail and avoid accidental impacts with the relatively thin sheet metal of the hanger bar. The downward slope of the nail permits easier hammer blows since the electrician typically stands below the height of the light fixture assembly, which is situated at or above head level during installation. 
     Each of the brackets may include an ear and an arm extending at an angle to the ear. The brackets may include a shelf attached to the arm. Each shelf may have a depression or an opening to receive a clip, and the clips may attach to a respective shelf. The spring clips are thus a discrete component that may be easily detached from the hanger bar by the user in the field. The clips are used to mount the hanger bar to T-bars of a drop down ceiling. 
     In one embodiment, there is a nail opening in each bracket arm. A nail extends through each nail opening. Each bracket arm is angled upwardly, such that the nails each extend at an upward angle relative to the first and second bars. In another embodiment, there is a nail opening in each bracket arm, a nail extends through each opening, and each bracket arm extends at an obtuse angle greater than 90 degrees relative to its respective ear, such that the nails extend outwardly relative to the bars. 
     The bracket may include a nail holding surface and at least one front panel spaced a distance from the nail holding surface. The front panel extends in a direction approximately perpendicular to the bars, the nail holding surface extending at an angle relative to the front panel. 
     The spring clips may be made from a variety of materials, such as spring steel, a very tough or elastic polymer, or from other materials known in the art that are suitable for clips. Each clip may be made of a single strip of spring steel, for example. In one embodiment, the clip and the hanger bar are made of different materials. 
     In a preferred embodiment spring clip, the foot has a length, and the foot may have an opening for a nail or other fastener. In one embodiment, the opening extends along most of the length of the foot. This opening may be used, for example, to nail or screw the clip to the underside of a joist. In one embodiment, the clip has an upper portion that is generally U-shaped, and a lower portion in which the first and second arms bend toward one another to form a neck. The first and second legs may extend from the respective first and second arms at the neck and curl away from each other to form a wide mouth. 
     The clips may have a top in between the first arm and the second arm, and a third arm for removably attaching the clip to a respective bracket may extend from the top of the clip. The third arm may include an indentation for engaging with one of a depression and an opening in the shelf. 
     In one embodiment, at least one of the ears is spaced from a respective bar to form a jog. One or both of the hanger bars may include a stop at an end, to limit the range of motion of the other hanger bar. The channel may be formed with at least one of a folded and a curled edge. 
     According to another embodiment of the invention, a hanger bar assembly for recessed lighting fixtures has a first bar having at least one of a folded and a curled edge forming a channel. A second bar is disposed within the channel, such that the second bar moves within the channel for a telescoping action. The first bar includes a first bracket on an end of the first bar, and a second bracket that may be on an end of the second bar. A first spring clip is detachably coupled to the first bracket. A second spring clip is detachably coupled to the second bracket. Each of the first and second clips have a pair of downwardly extending arms, a first leg extending from the first spring arm, a second leg extending from the second spring arm, an outwardly-extending foot on the second leg, and a third arm for removably attaching the clip to a respective bracket. Each of the brackets have a nail holder and a nail extending through the nail holder. The nails each extend at an outward angle relative to the first and second bars. Each of the brackets includes an ear and an arm extending at an angle to the ear, and a shelf attached to the arm. The clips attach to the respective shelves. The bracket includes a nail holding surface and at least one front panel spaced a distance from the nail holding surface, the front panel extending substantially perpendicular to the bars, the nail holding surface extending at an angle relative to the front panel, which angles the nail away from the hanger bar. 
     The foregoing and other objects and advantages of this invention will be apparent from the following more detailed description when taken in conjunction with the accompanying drawings of exemplary embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a preferred embodiment of hanger bars as used with a recessed lighting fixture in conjunction with ceiling joists; 
         FIG. 2  is a perspective view of a preferred embodiment of hanger bars as used with a recessed lighting fixture in conjunction with T-bars, thin rails, wires or cross-members; 
         FIG. 3  is a front elevational view of a hanger bar according to the present invention which is constructed from two discrete bars or rails that telescope relative to one another; 
         FIG. 4  is a bottom plan view of the hanger bar of  FIG. 3 ; 
         FIG. 5  is a rear elevational view of the hanger bar of  FIG. 3 ; 
         FIG. 6  is a top plan view of the hanger bar of  FIG. 3 ; 
         FIG. 7  shows the hanger bar in a contracted configuration; 
         FIG. 8  shows the hanger bar in an expanded configuration; 
         FIG. 9  is a perspective view of a hanger bar according to the present invention from the top perspective; 
         FIG. 10  is a detailed perspective view of a bracket and clip assembly; 
         FIG. 11  is a detailed perspective view of the hanger bar; 
         FIG. 12  is a detailed perspective view of a bracket and clip assembly; 
         FIG. 13  is a detailed view of the bracket and clip assembly from the top perspective with the clip removed; 
         FIG. 14  is a right end view of the hanger bar of  FIG. 9 ; 
         FIG. 15  is a left end view of the hanger bar of  FIG. 9 ; 
         FIG. 16  is an alternative embodiment hanger bar having one ear with a jog that moves the ear away from a co-planar arrangement to the rail to a parallel relationship to the rail. 
         FIG. 17  is a right end view of the hanger bar of  FIG. 16 ; and 
         FIG. 18  is a left end view of the hanger bar of  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a perspective view of a preferred embodiment of hanger bars  10 ,  12  used with a recessed lighting fixture  14  in conjunction with a ceiling that has ceiling joists  16 ,  18 . The fixture includes a cylindrical housing or can  20  supported on a rectangular frame  22 . Also resting on the frame  22  is a junction box  24  and conduits  26 ,  28  for receiving A/C power input and for providing power to a bulb holder and trim (not shown) that are held inside the can  20 . 
     The fixture  14  is supported on both sides by the preferred embodiment hanger bars  10 ,  12 . When the recessed lighting fixture  14  is being secured to a ceiling having wood ceiling joists such as  16 ,  18 , it is preferred that the hanger bars  10 ,  12  be nailed to the respective ceiling joists. Consequently, nails such as  30 ,  32  are provided at each end of the hanger bars  10 ,  12 . An electrician or installer may then hammer the nails  30 ,  32  into the joists using a hammer  34  illustrated in  FIG. 1 . Also at the ends of each hanger bar are spring clips  36 ,  38  that may be used to additionally secure the hanger bars to the ceiling joists. In particular, each clip  36 ,  38  includes a foot having an opening  40  through which a nail, screw or other fastener (not shown) may secure the clip to the underside of the respective ceiling joist. The particular geometry and construction of the respective clips  36 ,  38  will be discussed in more detail below. 
       FIG. 2  is a perspective view of the recessed lighting fixture  14  as mounted on T-bars  44 ,  46  of a drop-down ceiling. The clips  36 ,  38  and  42 , as well as a fourth clip (not shown), snap with pinching pressure onto the respective horizontal T-bars. In this scenario, the hanger bars do not need to be hammered into place on joists, as no nail is needed to secure the hanger bars to the horizontal T-bars  44 ,  46 . 
     As can be seen by comparing  FIGS. 1 and 2 , the hanger bars  10 ,  12  are versatile in that they may be secured to ceiling joists and/or to members of a drop down ceiling such as, for example, horizontal T-bars  44  and  46  of  FIG. 2 . The clips  36 ,  38  serve primarily to secure the hanger bars to members of the drop down ceiling. But as seen in  FIG. 1 , the respective clips each has a foot extending outwardly that may be nailed or otherwise secured to the underside of respective ceiling joists. 
     Considering now the construction of a preferred embodiment hanger bar, and referring to  FIGS. 3-6 , a hanger bar  10  such as shown in  FIG. 1  preferably has bars  60  and  62  that are slidably interconnected with one another. The bar  62  has folded or curled edges  64 ,  66  that create a channel through which the complementary bar  60  may slide. In this way, a telescoping bar assembly is constructed. This enables the user to adjust the length of the overall bar assembly, depending on the spacing of the horizontal T-bars, such as  44  and  46  of  FIG. 2 , or of the spacing of ceiling joists  16 ,  18 , as the case may require.  FIG. 7  illustrates a hanger bar  10  in a contracted configuration, while  FIG. 8  illustrates the same hanger bar  10  in a more expanded configuration. In this way, the hanger bar is adjustable to a desired length by the installer in the field. 
     Returning to  FIGS. 3-6 , nails or other fasteners  30 ,  32  extend through a respective bracket assembly or ears  70 ,  76 . Typically the nails  30 ,  32  in the preferred embodiment are angled upwardly from the nail head ( FIG. 3 ) and outwardly ( FIGS. 4 and 6 ) relative to the length of the bars  60 ,  62 . This angling of the nail or fastener facilitates the construction worker, electrician, or installer by allowing him or her room to hammer the nail without inadvertently hitting the thin, sheet-metal bar with the hammer head. The angling of the nail also results in more secure fixation of the respective bars to the respective joists, because the nail penetrates into the joist along an axis that is not parallel to the long axis of the hanger bar. With an angled nail, the weight of the light fixture bearing down on the hanger bars will be less prone to cause the nail to back out. It is noted, however, that the nails or other standard types of fasteners  30 ,  32  need not be used when the lighting assembly is affixed to T-bars  44 ,  46  of a drop down ceiling, as illustrated in  FIG. 2 , for example. 
     When a nail  30 ,  32  is used as the fastener, it is typically held in place on the bracket  70 ,  76  by friction fit. The nails may include a round, flange-like stop a slight distance from the flat head so that the nail can only be driven a predetermined distance into the ceiling joist. The tip or point of the nail when the nail is driven by hammer blow on its flat head passes completely through the hanger bar and into the ceiling joist. Small circumferential ribs may optionally be included near the tip for better gripping of the nail to the wood joist. 
     In  FIG. 5 , the back side of bar  62  is shown to have an optional crease or indentation  208  to improve stiffness or rigidity of the bar  62 . An indentation or bump  204  may be provided to interfere with a matching indent (not shown) on bar  60  to prevent the bars  60 ,  62  from disengaging when the bars are fully extended. 
       FIG. 9  is a top, perspective view the hanger bar  10  according to the present invention.  FIG. 10  in a perspective view illustrates in greater detail the clip and bracket assembly.  FIG. 11  is a perspective view of the bottom of the hanger bar  10 , and  FIG. 12  is a detailed view of the clip and bracket assembly. Each bracket  70 ,  76  has first ear portions  72 ,  78  and arm portions  74 ,  80 . Each arm  74 ,  80  defines a theoretical plane that is generally at an obtuse angle (greater than 90°) relative to the theoretical plane defined by each first ear portion  72 ,  78 . This obtuse angle can be best seen in the bottom and top plan views of  FIGS. 4 and 6 , respectively. The arms  74 ,  80  include nail apertures  110 ,  112  through which respective nails  30 ,  32  extend. Since each nail  30 ,  32  passes through the respective arms  74 ,  80  that are angled relative to first ear portions  72 ,  78 , which ear portions are generally parallel to each bar  60 ,  62 , the obtuse angle causes each nail  30 ,  32  to be likewise angled away from the bar  60 ,  62 . That is, since each nail  30 ,  32  has a flattened head at one end and a sharp point at the other, the flat head is positioned farther away from the bar  60 ,  62  than its point. Again, this is best seen in  FIGS. 4 and 6 . 
     Considering  FIG. 10 , a spring clip  38  having a generally U-shaped upper portion  82  is removably attached to the arm  80 . The clip  38  is preferably made from a high strength spring steel to enable a clamping or pinching action. It is bent into its compound curved U-shape. The pinching action allows the clip  38  to snap over and grip the T-shape cross-section of the T-bar  44 ,  46  securely. 
     The clip  38  includes a first spring arm  140 , a second spring arm  142 , a first leg  144 , and a second leg  146 . A foot  148  extends outwardly from the second leg  146 . The foot  148  includes an elongated aperture  40  through which a nail or other securing member can extend. The bracket  76  also includes bumper portions  84  and  86  which extend atop the detachable and removable clip  38  when the clip  38  is secured into place on the bracket  76 . These bumper portions  84  and  86  help retain the clip  38  in place on the assembly. Furthermore, the front surfaces of bumper portions  84 ,  86  collectively form a front panel  88  that is typically perpendicular to the plane of the bars  60 ,  62 , and the front panel  88  bumps and squarely engages with the flat side of the ceiling joist  16 ,  18 . 
     Referring again to  FIG. 10 , the planes represented at the ends of the hanger bars are not parallel. Specifically, front panel  88  defines a plane generally containing the faces of bumper portions  84  and  86 , which plane is generally perpendicular to the lengths of the bars  60 ,  62 . Another plane containing the arm  80  is angled and not parallel to the plane containing the front panel  88 . Since the aperture  112  receiving the nail  32  is formed on a surface in the angled arm  80 , the nail  32  is likewise angled. As a result, the angling of the nail  32  is such that its flat head extends away from the bar  62 . This angling of the nail allows the installer to hit the nail squarely with a hammer without accidentally striking the bar  62  in the same motion, because there is more room between the nail and the bar. This is in contrast to a nail that is oriented parallel to the bar. 
     Furthermore, the nail  32  as seen in  FIG. 10  is preferably angled so that the flat nail head is oriented downward, or the pointed end is directed upward. If the first and second bars  60 ,  62 , fall within a theoretical level, horizontal plane, then the nail is angled so that its flat head is lower than the plane and its pointed end is at or above the horizontal plane. The downward angling of the nail  32  enables the installer, who has the entire recessed lighting assembly situated at head level or above, to more easily strike at the nail head with his hammer from his position below. If the nail were parallel with the hanger bars or level with the horizontal plane, the installer standing from below the nail may not be able to strike the nail squarely on the head. 
       FIG. 13  is the assembly of  FIG. 10  with the clip  38  removed by the end user or installer in the field. To make the clip  38  detachable, a third spring arm  150  is provided atop the clip  38 . A space  152  is defined between the third arm  150  and the main body of the clip  38 . The third arm  150  may optionally include a leg  154  that aids in attaching the clip  38  to the bracket  76 . The bracket  76  may include an engagement portion  160  such as an opening in a horizontal shelf  162 . In the embodiment of  FIG. 13 , the clip  38  may be snapped into place on the shelf  162  by sliding the third arm  150  of the clip  38  forward such that the ridge  164  engages in the opening  160  of the bracket assembly. The opening  160  may alternatively be a depression rather than a full opening. A tight friction/pressure contact keeps the clip  38  joined to the bracket  76 . 
     As the third arm  150  is a spring arm, the arm serves to lock the clip  38  into place on the hanger bar  10  when desired. In the field, the installer or electrician can remove the clip  38  when desired. To remove the clip, the ridge  164  is disengaged from the opening or depression  160  of the ear assembly, and the clip may the be pulled free from the hanger bar with use of a pliers. 
     It is noted that the first arm  140  and the second arm  142  are spring arms. They are preferably formed in such a way that they curve inwardly toward one another at a region  170 ,  172 . The legs  144 ,  146  curve outwardly so as to form a neck or relatively narrow portion  174  in the clip. When this neck  174  is forced open, as when the clip is pushed down onto a horizontal T-bar, such as T-bar  46  as  FIG. 2 , the neck  174  is forced open and the resilience in the spring arms  140  and  142  urge the arms to clamp down on the T-bar  46 . This secures the hanger bar  10  to the T-bar  46 , thereby mounting the recessed lighting fixture  14  onto the horizontal T-bars. The distal outward curl of arms  140 ,  142  forms a wide mouth  176  that facilitates the installer to more easily align and push the clip onto the T-bar. Oftentimes, the installer&#39;s head is situated below the T-grid, so attaching the clips to the T-grid is performed overhead, above eye level and by feel, so the wide mouth  176  simplifies this task for the installer. If for any reason, perhaps due to space constraints in a ceiling area, the clips  36 ,  38  are not needed, the installer simply pops them off of the hanger bar  10 ,  12 . 
     In the above-described embodiments, the non-bracket end of one bar cannot slide past the bracket end of the other bar when the two bars are contracted toward the shortest overall length. As seen in  FIG. 9 , this occurs because the curved edges  64 ,  66  of one bar  62  bump into the ear  72  of the other bar  60  and can move no farther, thus limiting the lengthwise contraction of the entire hanger bar. On the other hand,  FIG. 16  illustrates an alternative embodiment of a hanger bar  10 ′ having a modified ear as part of a bracket on one end of one bar. In the embodiment of  FIG. 16 , one ear  72 ′ has jog  200  that moves the ear away from its coplanar arrangement with the hanger bar  10 ′ to be parallel with it. This jog  200  in  FIG. 16 , which spaces the ear somewhat from the bar  60 ′, provides a gap for the curved edges  64 ′,  66 ′ at the non-bracket end of the other bar  62 ′ to slide past ear  72 ′ of the bar  60 ′. This is sometimes known in the industry as a “pass-through” feature. 
     It is desirable in the alternative embodiment of  FIGS. 16-18  to provide other means to disable the pass-through feature, i.e., to prevent the non-bracket end of bar  62 ′ from sliding past the bracket  70 ′ of the other bar  60 ′. Hence,  FIGS. 17 and 18  illustrate an optional stop  202  which, in this case, is a small bent metal finger that blocks the non-bracket end of the bar  60 ′ from sliding forward. Thus, the stop  202  prevents the non-bracket end of the bar  60 ′ from extending past the bracket  76 ′ as the bars  60 ′,  62 ′ are contracted. To act as a stop when the bars are telescoped outwardly, an optional protrusion or indentation  204  may be provided on bar  60 ′, with a second protrusion or indentation (not shown) provided on bar  62 ′. As the bars are telescoped outwardly, the protrusions interfere with one another to prevent bar  60 ′ from sliding out of the channel and disassembling, and thereby limiting the range of motion of the bars relative to one another. 
     Unless otherwise described herein, conventional materials and manufacturing methods may be used to make the members of the present invention. For example, the hanger bar is preferably stamped and formed from sheet metal, but other materials and manufacturing methods may be employed. The clip is typically detachable, as described previously, but may alternatively be formed as part of the bracket. Various other modifications may be made to the present invention without departing from the scope thereof. Although individual features of embodiments of the invention may be shown in some of the drawings and not in others, those skilled in the art will recognize that individual features of one embodiment of the invention can be combined with any or all of the features of another embodiment.

Summary:
A hanger bar for supporting a recessed light fixture is attachable to ceiling joists or a T-bar grid of a drop down ceiling. First and second bars of the hanger bar slide and telescope. First and second spring clips are detachably coupled to the brackets at the ends of the first and second bars, respectively. Each of the first and second clips has a pair of downwardly extending arms bent inwardly toward one another, a first leg extending from a first arm, a second leg extending from a second arm, and an outwardly-extending foot on the second leg. The spring clips snap on to the T-bar grid. Each bracket includes a nail that is angled away from the hanger bar and downward so that the nail head is below the level of the hanger bar. The angled nails enable easy hammer strikes to attach the hanger bar to ceiling joists without accidental hammer blows to the hanger bar.