Abstract:
A lighting fixture with a housing having an opening and containing a fan and at least one heat-generating light bulb to produce light at the opening and a protective lens assembly below the housing opening. The protective lens assembly includes a top clear or translucent lens and a bottom clear or translucent lens having an opening and spaced from the top lens to provide a first ventilation gap between the lenses while protecting the interior of the housing. The fan may be operated to cool the light bulb by moving air through the ventilation gap and across the bulb.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This patent application claims the benefit of U.S. Provisional Patent Application No. 61/334,905 filed May 14, 2010. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention pertains to lighting fixtures structured to dissipate heat from hot-running light bulbs and ballasts mounted in the fixtures and to prevent debris from unintentionally escaping from the fixtures. 
       BACKGROUND 
       [0003]    Lighting fixtures used in gymnasiums or other sporting arenas, factories and other high-bay lighting applications or environments often contain hot-running light bulbs. These light bulbs produce a substantial buildup of heat in the lighting fixtures that can damage componentry including ballasts, refractors, housings, etc. The heat build up can also cause premature failure of the light bulbs. Because these fixtures are typically mounted well out of easy reach, maintenance is extremely difficult, so long life of the fixture and light bulbs is extremely desirable. 
         [0004]    Oftentimes, such fixtures are provided with safety thermostats that cut off power to the light bulbs if certain safety limit temperatures are exceeded. While this may prevent damage to the fixtures and premature bulb failure, it is obviously undesirable since the lighted gymnasium, factory, etc. will go partially or completely dark in such circumstances. 
         [0005]    Embodiments of the present invention prevent heat buildup in such lighting fixtures without interfering with the normal and expected appearance or operation of the lighting fixtures. They thereby improve fixture reliability and bulb longevity and minimize the chances of safety shut-off due to fixture overheating. Embodiments of the present invention also prevent the unintentional escape of debris from the lighting fixtures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a perspective view of a fully assembled lighting fixture in accordance with an embodiment of the present invention; 
           [0007]      FIG. 2  is a cutaway elevation front view of the lighting fixture of  FIG. 1 ; 
           [0008]      FIG. 3  is an assembly drawing illustrating the components of the lighting fixture of  FIG. 1 ; 
           [0009]      FIG. 4  is a view of componentry located with the housing of the lighting fixture of  FIG. 1 ; and 
           [0010]      FIG. 5  is a diagrammatic representation of a lighted facility including a lighting fixture in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Turning first to  FIG. 1 , a lighting fixture  10  of an embodiment of the invention is illustrated in a perspective view. Fixture  10  is intended primarily for mounting in gymnasiums or other sporting arenas, factories and other high bay lighting applications or environments, or in any other indoor applications where preferably ceiling mounting heights exceed about 15 feet. 
         [0012]    Fixture  10  includes a housing  12  with a housing opening  11  and a refractor  14  fitted to the housing opening. In alternate embodiments, the refractor may not be used and an enlarged housing may extend beyond the light bulbs  15 . 
         [0013]    As shown in  FIGS. 2-4 , housing  12  contains ballast components  18  for powering bulbs  15  and wiring (not shown) electrically connected to a series of lighting sockets  20  mounted on a circular lighting socket plate  22 . The lighting sockets preferably are arranged in a circular pattern on lighting socket plate  22  which is removably affixed to the underside of the bottom circular collar  24  of housing  12  and above the housing opening  11 . Although bulbs  15 , which are shown in place in the sockets in  FIG. 2 , are compact fluorescent light bulbs, other types of bulbs could be used. The bulbs produce light below housing opening  11 . 
         [0014]    A second circular plate  32  of the same diameter as plate  22  is located above the axial fan and attached to plate  22  by a series of spacers (not shown) about its periphery. Plate  32  has a central aperture  33  aligned with aperture  26  and of approximately the same diameter as aperture  26 . The fan is therefore sandwiched between plates  22  and  32  to form a fan/socket assembly  34 . 
         [0015]    A thermostat  36  may be mounted above ballasts  18  by bracket  19  which is affixed to the top of plate  32 . Ballasts  18  are spaced apart as shown to facilitate airflow and hence cooling by the fan. The thermostat may be set to a predetermined temperature (e.g., 130° C.) to warn of imminent fixture failure due to overheating, for example by lighting a warning light or tripping an alarm (not shown). 
         [0016]    Refractor  14  has a proximal opening  41  and a distal opening  50  and is positioned with its proximal opening  41  at housing opening  11 . When refractor  14  is clear or translucent, some of the light produced by bulbs  15  is projected through the refractor. The proximal opening  41  at the top of refractor  40  is encircled by an annular edge  42 . A circular retaining plate  44  is designed to sit below edge  42  to removably affix the refractor to housing  12  with the fan/socket assembly positioned in collar  24  at the bottom of housing  12 . The distal annular opening  50  of the refractor is encircled by an annular collar  52 . This collar facilitates attachment of a protective lens assembly  16 . 
         [0017]    Protective lens assembly  16  is positioned at the distal opening  50  of the refractor. As noted above, the protective lens assembly may be mounted within an enlarged housing when a refractor is not used. Lens assembly  16  comprises a bottom circular flat lens  56  and a top circular flat lens  59 . While it is preferred that the bottom lens have a larger diameter than the top lens, both lenses may be of the same diameter or the bottom lens may have a smaller diameter than the top lens. 
         [0018]    Although bottom lens  56  is illustrated with an axially positioned circular opening  60  which is preferably larger than the diameter of openings  26  and  33 , other opening shapes may be used and the opening(s) need not be centrally located. Lenses  56  and  59  are spaced from each other by pins  62  which are arranged along the periphery of lens  59  and are attached at either end to the two clear or translucent lenses, forming a first ventilation gap  64 . While any appropriate spacing could be used, the spacing preferably will be no greater than about one inch. The combination of lenses blocks direct access to the interior of the housing so that, inter alia, (1) objects cannot move into the fixture from below and damage components within the fixture; and (2) components within the fixture cannot fall through the lens assembly and escape the fixture. 
         [0019]    The outer edge of top lens  58  is spaced from the border of the distal opening  50  of the refractor to form a second ventilation gap  55  allowing an air stream A to pass between the edge of the top lens  58  and the border of the distal opening  50  of the refractor (as shown in  FIG. 2 ). In an alternative embodiment, the outer edge of the top lens  58  may be spaced from the border of the housing opening  11  to form a second ventilation gap allowing air stream A to pass between the edge of the top lens  58  and the border of the housing opening  11 . 
         [0020]    A protective wire grid  70  is located below bottom lens  56  to protect the lens and the interim of the fixture from damage for example in a gymnasium or athletic arena setting. The wire grid also protects people below the lighting fixture, like the lens assembly, from debris that might come loose in the fixture, for example, from a broken light bulb. 
         [0021]    Finally, an annular flexible locking band  72  with an opening  74  held together by a spring  76  and top and bottom annular lips  77  and  78  is provided to capture and hold the lens assembly and the protective grid at the bottom of the refractor along collar  52 . 
         [0022]    Once in place, the lens assembly facilitates air flow through the fixture to prevent it from overheating while also preventing any broken light bulbs or other debris from escaping the fixture and falling onto spectators or others disposed below the fixture. 
         [0023]      FIG. 5  shows a diagrammatic representation of a lighting facility  100  according to an embodiment of the invention. The facility uses at least one lighting fixture  102  as described above attached at a powered junction  104  via a cord  106  to at least one upper supporting section (ceiling)  108 . Any number of such lighting fixtures could be mounted within facility  100 . Lighting fixture  102  projects light generally downwardly towards the floor of the facility  110 . Facility  100  may be a gymnasium or arena designed for athletic play and optimally for spectators (not shown). The facility may have stands for holding spectators and/or courts, grounds, or otherwise designated areas for competitive sporting events. 
         [0024]    Lighting fixture  10  operates as follows:
       1. First it is assembled and positioned where desired, typically by hanging from a ceiling by a cord  80  which includes the necessary electrical wiring (not shown) to supply current to the ballasts of the fixture. The assembled fixture will contain bulbs  15  ready to be lighted when current is supplied by a ballast or other current source.   2. Once the fixture is lighted, illumination is provided both from the sides through acrylic refractor  14  and through lens assembly  16 .   3. At the same time, power is provided to fan  30  causing fan blades  32  to begin rotating. The fan blades are oriented to produce an upward flow of an airstream A which is drawn through opening  60  in bottom lens  56  and the spacing  64  between the top and bottom lenses (the first ventilation gap), the spacing between the edge of the top lens and the exterior of the fixture (the second ventilation gap) and then through apertures  26  and  33  in plates  22  and  32  before passing through orifices  17  at the top of the housing. Thus, as airstream A moves past light bulbs  15 , it cools them in the process and prevents overheating of the overall lighting fixture.       
 
         [0028]    Thus, the invention makes it possible to move air through the fixture to cool it without impairing its ability to prevent debris from escaping through the bottom of the lighting fixture while also safeguarding the interior of the fixture. 
         [0029]    All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
         [0030]    The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
         [0031]    Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the invention.