Patent Publication Number: US-7903430-B2

Title: Recessed light ballast mount

Description:
BACKGROUND OF THE INVENTION 
     A. Field of the Invention 
     The present invention relates to lighting fixtures. More particularly, the present invention relates to a lamp ballast case that has a bracket at an advanced position for withdrawing the ballast to fit in a tight space about fluorescent lamp fixtures. 
     B. Description of the Prior Art 
     Compact fluorescent lamp fixtures have been developed to offer an effective and permanent solution for energy-efficient lighting at home and businesses. More recent advancement may be found in product lines under the trademark ‘HALO’ as described in US Patent Application Publication No. US 2008/0025031 of Wronski et al. The application describes a lighting fixture designed for recessed lighting on insulated ceilings with multiple adjustment features to facilitate installation and illumination customization. The three major components of the fixture for use with a fluorescent lamp are a lamp housing, a junction box and a replaceable ballast all mounted on telescoping bar hangers, which are in turn attached to construction studs or joists. The ballast is surface mounted by screws to a planar mounting plate of the junction box. However, due to the operational heat of the ballast that will add to the lamp heat, the ballast must be mounted on the junction box at the other side of the lamp housing at the cost of a maintenance personnel&#39;s problem. As shown in  FIG. 1  attached to show the prior art, the junction box  1  of the lamp housing  2  is closed at sides by a first remountable wall plate  3  close to a ceiling opening  4  and the opposite ballast mounting plate  5 , which is blocked from normal view through the opening  4 . A spring clip  6  holds both plates  3  and  5  onto open ends of the junction box  1 . The ballast  7  with end flanges is screw fastened to plate  5  and faces away from the first plate  3 . The necessary heat dissipation from the lamp and ballast  7  needs a good physical clearance between the components for air circulation but at the same time is subjected to certain dimensional limit. 
     Eventually, when it is time to repair the lamp by replacing inoperable ballast  7 , housing  2  is supposed to be first detached from its fixture base  8  but the existence or location of ballast  7  is impossible to detect from under the ceiling through the access opening  4  without a prior knowledge or consulting the original installation guide. In addition, identifying and releasing the plate  5 /ballast  7  assembly are not all necessary to replace the bad ballast  7 . It must be replaced with a new one by unscrewing and screwing at least two screw fasteners on the plate  5 . 
     Above all, such inability to access to the major connected part may undermine the stated lighting fixture improvements when many of these ballasts will reach the service life and need replacements in series. An ideal ballast fixture for this purpose should be associated with the fixture junction box at an easy location to find and replace while taking up less space of the fixture. 
     In view of the foregoing need for improvement and others, an object of the present invention is to provide a lamp ballast with a built-in bracket that is integral to its casing and attaches directly to a junction box of a fluorescent lighting fixture. 
     Another object of the present invention is to provide a lamp ballast with an advanced bracket section for mounting on a junction box resulting in little to none protrusion from the surface of the junction box to freely place the ballast at the best location to work with during maintenance. 
     Yet another object of the present invention is to provide an economic solution to encase a lamp ballast as well as fasten it to a lighting fixture without adding a third component and instead with loosing existing fastening hardware and its metal weight. 
     SUMMARY OF THE INVENTION 
     A fluorescent lamp ballast of the present invention may be used in associated with a recessed lighting fixture and is adapted to a direct low profile mounting on a junction box of the lighting fixture by a varying degree of recessed positioning. 
     In one embodiment, the lamp ballast may comprise: a ballast circuit on a board; a package for enclosing the circuit board save electric wires from and to the ballast circuit at multiple sides including a top surface, bottom surface and sidewalls extending between the top and bottom surfaces to connect the same surfaces; and a flange extending from the sidewalls of the package at a predetermined level between the top and bottom surfaces. Thus, the flange provides an integral bracket of the ballast for a varied degree of recessed mounting of the ballast on the lamp fixture. The package and circumferential rim are integrally molded of thermoformable resin. Or, they may be made of folded sheet metal. The flange has a male and female fastening sections at opposite ends for mounting and demounting with respect to complementary sections of the lamp fixture. 
     In a preferred embodiment of the present invention, a ballast with a built-in bracket for attachment to a fluorescent lamp fixture comprises a ballast circuit on a board; an upper case including a base plane, two opposite perpendicular planes, two opposite sidewalls between the perpendicular planes and an entrance for introducing the circuit board into the package; and a generally planar lower case overextending beyond the area of the upper case and having a predetermined depth of large central recess shaped for fixedly inserting the upper case, whereby the overextending area of the lower case provides an integral bracket of the ballast for a varied degree of recessed mounting of the ballast on the lamp fixture. The upper case is made of sheet metal cut and folded into an open box structure. The lower case is made of sheet metal by deep drawing. 
     Alternatively, the lower case may be made of sheet metal cut and folded into an open tray structure. The lower case has a male and female fastening sections at opposite ends for mating with complementary sections of the lamp fixture. 
     Embodiments of the invention will now be described by way of example with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational view of lighting fixture of prior art. 
         FIG. 2  is an exploded perspective view of a lighting fixture employing a ballast according to one embodiment of the invention. 
         FIG. 3  is an exploded perspective view of the ballast of  FIG. 1 , showing a stamped bracket. 
         FIG. 4  is a cross sectional view of the ballast taken along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a perspective view of a bottom case under shaping according to an alternate embodiment of the present invention, showing a folded bracket. 
     
    
    
     Similar reference numbers denote corresponding features throughout the attached drawings. 
     Call Out List of Elements 
     
       
         
           
               
               
               
             
               
                   
               
             
            
               
                 1: Junction Box 
                 2: Lamp Housing 
                 3: First Wall Plate 
               
               
                 4: Ceiling Opening 
                 5: Ballast Mounting Plate 
                 6: Spring Clip 
               
               
                 7: Ballast 
                 8: Fixture Base 
                 9: Screw Tab 
               
               
                 10: Ballast 
                 11: Bottom Hole 
                 12: Ballast Case 
               
               
                 13: Ballast Circuit 
                 14: First Shell 
                 16: Entrance 
               
               
                 18: Second Shell 
                 20: Niche 
                 22: Base Plane 
               
               
                 24: Perpendicular Plane 
                 26: Junction 
                 28: Sidewall 
               
               
                 30: End Flap 
                 32: Aperture 
                 34: Bracket 
               
               
                 36: Hook 
                 38: V-notch 
                 40: Latch 
               
               
                 41: Bonding Material 
                 42: Opening 
                 44: Bushing 
               
               
                 108: Second Shell 
                 110: Bottom Plane 
                 112: Sidewall 
               
               
                 114a, 114b: Trapezoid 
                 116: Hook 
                 118: Perpendicular 
               
               
                 Plane 
                   
                 Plane 
               
               
                 120: Trapezoid Plane 
                 122: End 
                 124: V-notch 
               
               
                 126: Central Opening 
                 128: End Flap 
                 130: Latch 
               
               
                   
               
            
           
         
       
     
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to  FIG. 2 , rectangular lamp fixture base  8  has multiple clips for slidably holding paired hanger bars (not shown) to fix the base  8  adjustably to building joists about the ceiling openings designated to make illuminations. The fixture base  8  fixedly supports junction box  1  and fluorescent lamp housing  2  having an internal lamp socket that is wired to a power line leading through junction box  1  to which a remote switch is also connected. Fixture base  8  also has a large brimmed hole  11  that coincides with the ceiling opening. Extending from around the hole  11  are multiple screw tabs  9  for initially fastening lamp housing  2  to base  8  and eventually become release points to remove housing  2  to gain access to the electric components on base  8 . Thus, upon electrical connection inside junction box  1  a lamp in housing  2  provides a recessed illumination down through the ceiling opening. 
     According to the present invention, a ballast  10  shown partially cut away is adapted to mount onto base  8  almost frontally facing bottom hole  11  of base  8 . Ballast  10  has a metal case  12  for enclosing a known electronic ballast circuit  13  ( FIG. 4 ) for providing an appropriate electric power for the fluorescent lamp, which in this fixture design may use a compact lamp type. Ballast case  12  may be applied to alternative electromagnetic ballasts successfully. Case  12  comprises a first shell  14  with an entrance  16  for accommodating the circuit and a second shell  18  shaped like a tray with a central niche  20  for snuggly receiving first shell  14  to close entrance  16 . The first shell can be made of plastic or metal. 
       FIG. 3  shows ballast  10  within case  12  that may be made of a single sheet metal cut and folded into an open box that includes a rectangular base plane  22 , two opposite perpendicular planes  24  connected to base plane  22  via optional chamfer junctions  26  and two sidewalls  28  shaped to close the side polygonal apertures formed by edges of base plane  22 , folded junctions  26  and folded perpendicular planes  24 . Each of perpendicular planes  24  has two end flaps  30 , which are folded over proximal sidewalls  28  to keep them secured together. Also formed on each perpendicular plane  24  are two semicircular apertures  32  for interconnecting first shell  14  with the counterparts of second shell  18 . Apertures  32  are oriented so that straight edges are closer to the open edges of shell box  14 . Bracket  34  may be stamped as shown in  FIG. 3 . 
     On the other hand, second shell  18  is made of another sheet metal that may go through a deep drawing process to construct an enclosure cover having central niche  20  sized to fit over a predetermined height of first shell  14 . The rest of niche  20  extends in a plane parallel to base plane  22  of first shell  14  and becomes a working member of bracket  34  for mounting ballast  10  on junction box  1 . Bracket  34  may be shaped similarly to the first remountable wall plate  3  in that it has a bent hook  36  at one side edge for a latching penetration into a slot (not shown) of junction box  1  and a V-notch  38  formed at the opposite side edge for mating with spring clip  6  of junction box  1 . 
     A firm attachment between first and second shells  16 ,  18  is provided by four depressed latches  40  that protrudes inwardly of niche  20  at the corresponding level to engage the straight edges of apertures  32  when the first shell  14  is assembled with internal ballast circuit  13  and then pressed into second shell  18 . The preinstalled ballast circuit  13  may be attached to inner surfaces of first and second shells  14 ,  18  by a bonding material  41  for stability. Centrally of niche  20  there is formed an opening  42  for passage of wires in and out of the ballast circuit. To ensure insulation of the ballast wires, a plastic bushing  44  may be installed to smooth the inner diameter of opening  42 . 
     Alternatively, the bushing  44  can be made as a stamped bushing which is integral to the second shell by stamping a round edge into the face of the second shell in the same operation as the stamping of the opening. In this way, the wires avoid a sharp surface while avoiding the use of a plastic bushing. 
     When assembled, case  12  becomes a firm unit that has integral bracket  34  surrounding the sides of ballast  10  as shown well in  FIG. 4  wherein ballast  10  has been turned 90 degrees for attachment to the upright junction box  1 . The position of bracket  34  along the perpendicular planes  24  is adaptable to particular application of lamp fixtures. In an extreme case of junction box  1 , bracket  34  may extend flush with base plane  22  of first shell  14  so that there is virtually no protrusion from junction box  1 , which still has the enough interior space remained to house the entire ballast in first shell  14  besides its primary occupants of electric wires and the associated connectors. Because junction box  1  has occupied unused space in the lamp fixture as well as a redundant ballast mounting plate  5  as shown in  FIG. 1 , the inventive provision of ballast  10  with the positioning bracket advances the conventional art of ballasting the lamp in two ways: new serviceable location of ballast through space saving and a substantial saving of material by simply negating the necessity of the component of mounting plate  5 . 
     Alternatively, ballast  10  of the present invention may be packaged by a case formed of a different material such as thermoplastic resin. In such case, a single piece enclosure may be molded about ballast circuit  13  leaving the necessary connecting wires leading from the enclosure. A bracket similar to bracket  34  complete with hook  36  and V-notch  38  may be integrally formed to the enclosure at any levels between the top and bottom surfaces of the enclosure varying the degree of protrusion of ballast  10  with respect to junction box  1 . Inside the enclosure, ballast circuit  13  may be encapsulated by appropriate filler for protection. 
       FIG. 5  shows an alternative embodiment of second shell presently assigned numeral  108 , which is partially processed to show both before and after folding of a blank sheet metal. Here, the shell metal is folded with respect to a bottom plane  110  to form one of two opposite rectangular sidewalls  112  and a trapezoid plane  114   a  extending from sidewall  112  at 90 degrees externally and having a bent hook  116 . Next to sidewall  112  and trapezoid plane  114   a  are one of two opposite perpendicular planes  118  and an outwardly folded trapezoid plane  120  that meets with trapezoid plane  114   a  along their proximal ends  122 . The other trapezoid plane  114   b  may have a V-notch  124  for accepting the engagement of spring clip  6  of junction box  1  shown in  FIG. 2 . A central opening  126  is formed similar to opening  42  of second shell  18  in the earlier embodiment for the passage of wires. 
     In order to reinforce the enclosure cover resulting from first shell  108 , two opposite end flaps  128  may be formed on the respective perpendicular planes  118  to crimp over the proximal sidewalls  112  and bind them together. Perpendicular planes  118  also include inwardly protruding latches  130  at the corresponding locations to apertures  32  of first shell  14  that may fit perfectly with this embodiment of second shell  108 . The advantage of this folding second shell  108  is that it needs lighter folding works compared to the high-pressure deep drawing method. 
     Therefore, while the presently preferred form of the lamp ballast with advanced bracket has been shown and described, and several modifications thereof discussed, persons skilled in this art will readily appreciate that various additional changes and modifications may be made without departing from the spirit of the invention, as defined and differentiated by the following claims.