Patent Publication Number: US-7585088-B2

Title: Fluorescent lamp fixture

Description:
BACKGROUND OF THE INVENTION 
   The field of the present invention is fixtures and components for fluorescent lamps. 
   Fluorescent lighting has long provided cost effective, efficient and low heat artificial light sources finding utility, inter alia, for overhead lighting in buildings and other structures. Such lighting fixtures typically employ multiple elongate fluorescent tubes arranged horizontally to one side of a reflector and covered by a lens. Such fixtures are commonly found supported on a ceiling of a building structure. 
   With the advent of mechanisms for enhancing brightness and reducing striking requirements in colder environments, such fluorescent lamps are capable of being employed in garage environments where the ambient temperature is not maintained above the outdoor temperature. One such device for enhancing brightness and striking is illustrated in U.S. Patent Publication 2006/0227552, published Oct. 12, 2006 in the name of Glenn M. Tyson, the disclosure of which is incorporated herein by reference. 
   In garages having a typical commercial garage layout, a center aisle flanked by parking spaces extending laterally away from the aisle have recommended standards employing a maximum/minimum horizontal illumination uniformity ratio of 10:1. With central lighting in the aisles, the maximum light intensity is found beneath the fixtures while the minimum is found at the outside edges of the parking spaces. Typically, flood light luminaires employed in rows parallel to the center aisle are spaced and arranged to meet the appropriate standard. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a fluorescent lamp fixture which employs a fixture housing, an elongate first reflector to one side of the housing and at least one set of fluorescent lamp sockets extending outwardly of the first reflector to define fluorescent lamp mounting location for receipt of fluorescent tube(s). 
   In a first separate aspect of the present invention, an elongate second reflector is displaced from and faces the first reflector. The first reflector extends laterally in both directions beyond the second reflector and the second reflector extends laterally outwardly of the fluorescent lamp mounting location. This second reflector has two reflective longitudinal surfaces on either side to reflect light from the adjacent fluorescent lamp mounting laterally of the second reflector directly from the fixture housing. This arrangement directs such light outwardly to reduce the maximum/minimum horizontal illumination uniformity ratio. 
   In a second separate aspect of the present invention, an elongate second reflector is displaced from and faces the first reflector. The first reflector extends laterally in both directions beyond the second reflector and the second reflector extends fully across and laterally outwardly of the fluorescent lamp mounting location. This second reflector has two reflective longitudinal surfaces on either side to reflect light from the adjacent fluorescent lamp mounting locations laterally of the second reflector. This arrangement reduces glare downwardly and directs such light outwardly to reduce the maximum/minimum horizontal illumination uniformity ratio. 
   In a third separate aspect of the present invention, an elongate second reflector is displaced from and faces the first reflector. The first reflector extends laterally in both directions beyond the second reflector and the second reflector extends fully across and laterally outwardly of the fluorescent lamp mounting location. This second reflector has two reflective longitudinal surfaces on either side to reflect light from the adjacent fluorescent lamp mount laterally of the second reflector. The first reflector is a diffuse reflector while the second reflector is a specular reflector. This arrangement eliminates light shining directly down from the fluorescent lamp mounting locations. The reflective surfaces are chosen to provide additional diffuse light downwardly to fill in beneath the second reflector while efficiently transmitting direct light outwardly to the lateral extent of the coverage. The reflective longitudinal surfaces direct such light outwardly to reduce the maximum/minimum horizontal illumination uniformity ratio. 
   In a fourth separate aspect of the present invention, an elongate second reflector is displaced from and faces the first reflector. The first reflector extends laterally in both directions beyond the second reflector and the second reflector extends laterally outwardly of the fluorescent lamp mounting location. This second reflector has two reflective longitudinal surfaces on either side to reflect light from the adjacent fluorescent lamp mount laterally of the second reflector. The reflective longitudinal surfaces direct such light outwardly to reduce the maximum/minimum horizontal illumination uniformity ratio. A refracting lens is arranged over the fluorescent lamp mounting locations and the reflectors to distribute and diffuse light from the fixture. This refracting lens may further mount the second reflector. 
   In a fifth separate aspect of the present invention, an elongate second reflector is displaced from and faces the first reflector. The first reflector extends laterally in both directions beyond the second reflector and the second reflector extends laterally outwardly of the fluorescent lamp mounting location. This second reflector has two reflective longitudinal surfaces on either side to reflect light from the adjacent fluorescent lamp mount laterally of the second reflector. A refracting lens is arranged over the fluorescent lamp mounting locations and the reflectors to distribute and diffuse light from the fixture. Overcenter latches are mounted on the fixture housing and include engagements depending therefrom to engage the refracting lens. Some of the engagements include springs biasing the engagements away from the refracting lens to limit the number of attachment points with the overcenter latches unlatched. This allows for a more facile removal of the refractive lens. 
   In a sixth separate aspect of the present invention, the elongate second reflector is displaced from and facing the first reflector. The first reflector extends laterally in both directions beyond the second reflector and has a lateral cross section comprising two concave sections. The concave sections are each further defined by substantially planar outermost, middle, and inner elements, which are disposed at different angles relative to plane of the fluorescent lamp mounting location. The second reflector extends laterally outwardly of the two fluorescent lamp mounting locations lying in a plane and has reflective longitudinal surfaces on either side to reflect light coming from the adjacent fluorescent lamp mounting location laterally of the second reflector. At least one set of fluorescent lamp sockets extends outwardly from the first reflector toward the second reflector to define a fluorescent lamp mounting location directly between the first reflector and the second reflector and longitudinally aligned with the first reflector and the second reflector. 
   In a seventh separate aspect of the present invention, the second reflector further comprises an elongate flat section between the reflective longitudinal surfaces. The longitudinal reflective surfaces may be provided at an angled relation relative to the plane of the fluorescent lamp mounting location. This angled relationship may be at a 43° angle relative to the plane of the fluorescent lamp mounting location. 
   In an eighth separate aspect of the present invention, the angles for the outermost and middle elements may be 21° and 8°, respectively, and for the inner element, 14° in the opposite rotation. 
   In a ninth separate aspect of the present invention, any of the foregoing aspects are contemplated to be employed in combination to greater advantage. 
   Thus, it is an object of the present invention to provide an improved fluorescent lamp fixture. Other and further objects and advantages will appear hereinafter. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of a fluorescent lamp fixture. 
       FIG. 2  is a cross-sectional view looking at a transverse cut of the assembled fixture. 
       FIG. 3  is a partial perspective view of a housing with an overcenter latch. 
       FIG. 4  is a cross-sectional view of the fluorescent lamp fixture illustrating overcenter latches to retain the refractive lens. 
       FIG. 5  is a polar graph of candela in vertical planes through various horizontal angles from tests of a preferred embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Turning in detail to the drawings,  FIG. 1  illustrates a lamp fixture in exploded perspective as including a ceiling housing  10 , a gasket  12  for the ceiling housing  10 , two wireway covers  14  and an optic subassembly  16 . The ceiling housing  10  includes a flat panel  18 , end plates  20  and sidewalls  22 . A heater *(not shown) in accordance with U.S. Patent Publication 2006/0227552 is advantageously employed in outdoor garage applications. 
   Turning to  FIG. 2 , the optic subassembly  16  is shown in greater detail to include sockets  24 ,  26 . The sockets  24 ,  26  each form half of a socket set of opposed sockets  24 ,  26  for a fluorescent lamp. The sockets extend outwardly from the optic subassembly  16  of the ceiling housing  10 . The fluorescent lamp sockets  24 ,  26  thus define two fluorescent lamp mounting locations between the opposed sockets  24 ,  26  which lie in a plane parallel to that of the housing  10  and which mount parallel fluorescent lamps  28  that are in turn parallel to the optic subassembly  16  and in longitudinal alignment as well. The fluorescent lamps  28  in this embodiment are bi-pin 54 watt lamps, other wattages are contemplated as well. 
   The optic subassembly  16  also includes an elongate first reflector  30 . This reflector  30  forms the lower side of the ceiling housing  10  and extends longitudinally thereof. The reflector is formed in lateral cross section with two concave sections  32 ,  34  with the concavity facing toward the defined fluorescent lamp mounting locations. The angles to the plane of the fluorescent lamp mounting locations found in each of the concave sections  32 ,  34  which have been found to be advantageous in this one particular fixture include a 21° angle for the outermost reflecting element  36 , an 8° angle for the middle element  38  and a 14° angle in the opposite rotation for the inner element  40 . A small center section  42  between the concave sections  32 ,  34  is parallel to the plane of the fluorescent lamp mounting locations. 
   The first reflector  30  extends laterally outwardly of the fluorescent lamp mounting locations with the lamp sockets  24 ,  26  being mounted to the sections  40 . Light from the lamps  28  themselves and direct reflection from this first reflector  30  provide a lateral spread of light from the fixture. To increase the dispersion of light from the first reflector  30 , the surface thereof is reflective white. This creates a diffuse reflector. 
   An elongate second reflector  44  is located to the other side of the defined fluorescent lamp mounting locations from the first elongate reflector  30 , thus placing the fluorescent lamp mounting locations directly between the two reflectors  30 ,  44 . This elongate second reflector  44  extends fully across below the fluorescent lamp mounting locations so that no direct light from the lamps  28  shines directly downwardly. This elongate second reflector  44  also extends laterally outwardly of the two fluorescent lamp mounting locations to a small extent but not so far as the elongate first reflector  30 . Two reflective longitudinal surfaces  46 ,  48  are arranged at 43° to the plane of the fluorescent lamp mounting locations to reflect light from the adjacent fluorescent lamps  28  laterally of the second reflector  44  to extend the illumination further from the fixture. An elongate flat section  50  spans between the two reflective surfaces  46 ,  48  to have the elongate second reflector  44  extend fully across below the fluorescent lamps  28 . The elongate second reflector  44  is a specular reflector with a polished surface to improve the efficiency of reflection in the lateral direction. 
   A refracting lens  52  surrounds the first and second reflectors  30 ,  44  and the fluorescent lamp mounting locations. The refracting lens  52  preferably extends to the end plates  22  of the housing. Further, a gasket  54  may be employed with the refracting lens  52 . The refracting lens  52  is a diffuser lens of clear plastic having bumps or angles on the surface to further disperse light. The elongate second reflector  44  is conveniently mounted to the refracting lens  52  as can be seen in  FIG. 2 . 
   In operation, light from the fluorescent lamps  28  is directed laterally between the reflectors  30 ,  44  through the refracting lens  52 . Additionally, light from the fluorescent lamps  28  encounters the elongate first reflector  30  and is generally reflected with dispersion based on the surface of the reflector  30 . Thus, light is diffused to the reflective longitudinal surfaces  46 ,  48  and then laterally therefrom. Additionally, diffused light is reflected from the elongate first reflector  30  downwardly to fill in the area blocked beneath the elongate second reflector  44 . Thus, full dispersion of the light reflected from the elongate first reflector  30  is achieved. Additionally, light directly from the fluorescent lamps  28  is also reflected in a more direct and efficient manner laterally of the fixture off of the elongate second reflector  44  because of the specular reflector surface. The refracting lens then diffuses this light as well to achieve an overall advantageous light pattern for commercial type garages. 
   The performance of a fixture constructed in accordance with the illustrated preferred embodiment is shown in  FIG. 5 . Depicted is a polar graph with a maximum candela of 1223. This maximum is located at the horizontal angle of 90° at a vertical angle of 65°. In  FIG. 5 , line No.  1  is taken in a vertical plane through the horizontal angles 90°-270°. Line No.  2  is taken in a vertical plane through the horizontal angles 0°-180°. Line No.  3  is taken in a vertical plane through the horizontal angles 45°-225°. Line No.  4  is taken in a vertical plane through the horizontal cone angle of 65°. 
     FIGS. 3 and 4  illustrate a latch mechanism employed to attach the lens  52  to the housing  10  and more specifically the sidewalls  22 . Six overcenter latches  56  are spaced along either side of the housing  10 . The latches  56  have an actuator link  58  which is pivotally mounted to a latch frame  60 . An engagement  62  pivotally depends from the actuator link  58  to engage the refracting lens  52 . The actuator link  58  moves overcenter to retain the refracting lens  52  in the locked position. When opened, the engagement  62  may continue to be hooked to the refracting lens  52 . With multiple such latches, it becomes difficult to conveniently remove the refracting lens  52  with the depending engagements  62  continuing to be engaged with the refracting lens  52 . Consequently, a leaf spring  64  is mounted to the latch frame  60  by means of a fastener  66 . The leaf spring  64  is configured to force the depending engagement  62  away from the refracting lens  52  so as to not inhibit removal of the refracting lens  52  from the housing  10 . By having some but not all of the overcenter latches  56  employing a leaf spring  64  to bias the engagement  62  away from the refracting lens  52 , two latches  56 , one on either side of the housing  10  for example, will retain the refracting lens  52  until the engagements  62  are deliberately moved from engagement. 
   Thus, an improved fluorescent lamp fixture is described. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the appended claims.