Abstract:
A security lighting system is provided for convenient mounting to a standard electrical junction box. The security light fixture includes a housing, a cantilevered arm extending from the housing, and a back plate on an end of the cantilevered arm. The back plate has a reinforced attachment structure capable of supporting the bending moment of the heavy, cantilevered light structure. The attachment structure may include, for example, a reinforced cone. The back plate and cantilevered arm may be integrally formed for convenient manufacturing and added structural strength. The fixture may include a cross bar for attaching to the junction box, with the cross bar serving to interconnect the junction box with the back plate. In one embodiment, the security lighting system provides an option of electrically interconnecting the system to a standard j-box or, alternatively, to an electrical conduit, as desired. In another embodiment, the cross-section of the back plate may have a different shape than the cross-section of the junction box.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a non-provisional utility patent application based on Provisional Application Ser. No. 60/754,105, filed Dec. 27, 2005 and titled, “AREA SECURITY LIGHT WITH ADAPTABLE MOUNTING HARDWARE,” from which priority is hereby claimed and which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Area security lights are usually mounted outdoors in order to project a wide swath of visible light. They are employed at a variety of facilities, such as commercial (shopping malls, stores, sports stadiums, tennis courts), industrial (factories, warehouses, farms), and government or military facilities (airports, military bases). A light is typically mounted to a wall, a pole, or other structure. To achieve the largest area of lighting, the area security light fixture has a horizontally extending, cantilevered arm to hold the light source away from the wall, pole, or other structure. By moving the light source away from the wall, pole, or building, the cantilever arm gives the security light greater light dispersion around a 360° circumference. 
     Installation of this type of light has been difficult. Typically, the end user has been required to nail or bolt the light to the structure, then run an electrical conduit to the light. Often it has been inconvenient and time consuming to run the conduit to the light. It would be more convenient to mount the light to a standard outlet box. But the cantilevered arm must support bulky and heavy electrical components, such as a ballast, a transformer, a starter, and the like, which are normally needed for metal halide, mercury vapor, high pressure sodium, fluorescent, and sometimes halogen type light sources of security light systems. 
     What has been needed to this point is a mounting system that allows an end user to conveniently mount a heavy security lighting system to a standard outlet box. It is also desirable at times to provide the end user with a security lighting system that can be conveniently interconnected with the user&#39;s choice of a either an outlet box or an electrical conduit. The invention disclosed herein meets these and other needs. 
     SUMMARY OF THE INVENTION 
     The present invention provides a security lighting system that can be conveniently mounted to a standard electrical outlet. In an alternative embodiment, the security lighting system can be electrically interconnected to the user&#39;s choice of either a standard electrical outlet or a conduit. In this way, a single security light mounting structure may be used in a variety of different mounting configurations. 
     According to one embodiment of the invention, a security light fixture has a housing, a cantilevered arm extending from the housing, and a back plate on an end of the cantilevered arm. The back plate may optionally be reinforced with ribs. The back plate preferably has a reinforced attachment point structure capable of supporting a bending moment of at least 60 in-lbf. (inch-pounds-force), in order to support a heavy security light assembly. The reinforced attachment point structure may be any of a variety of different structures. In one embodiment, the reinforced attachment point structure is a reinforced cone having a threaded opening to receive, for example, a threaded mounting shaft. 
     Embodiments of the present invention may have different features. For instance, the ribs may extend in a crossing pattern. The back plate and arm may be integrally formed, for convenient manufacturing and added structural strength. The security light fixture may include a cross bar for attaching to an electrical junction box or outlet box. The cross bar may have, for example, one or more mounting slots and/or mounting holes for mounting the cross bar to an outlet box or other structure. The cross bar may be attached to the back plate with an attachment member such as a threaded stud. 
     For adaptability, some embodiments of the security light may include a removable bottom plate. The bottom plate may have an opening that can be covered up as desired. For example, a cover may be used to cover the opening when the light is to be mounted to an electrical outlet box. But, in a second mode that is typically employed when connecting the security light to an electrical conduit rather than to an outlet box, the cover is removed from the opening. 
     It is noted that the cross bar mounting system may provide additional mounting versatility when, for instance, the outlet box has an unusual cross-sectional shape. That is, the back plate may have a first cross-section, while the outlet box has a second, different cross-section. This may be useful when, as one example, the back plate has a square cross-section and the outlet box has a circular, triangular, or other cross-section. 
     It is to be understood that the present invention is not limited to the specific examples described herein. For example, while the mounting structure of specific examples of the present invention may typically be made of steel, other suitable materials may be used. Also, it should be understood that there are numerous features and variations that are described herein that form part of the invention. Consequently, the present invention is to be understood with reference to the detailed description below, the drawings, and the claims, and is not limited by this summary or by description of any one particular embodiment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a right side elevational view of a security light fixture according to one embodiment of the present invention; 
         FIG. 2A  is a back end view of the security light fixture of  FIG. 1 ; 
         FIG. 2B  is a cross-section taken along line A-A of  FIG. 2A ; 
         FIG. 3  is a left side elevational view of the security light fixture of  FIG. 1 ; 
         FIG. 4  is a front elevational view of the security light fixture of  FIG. 1 ; 
         FIG. 5  is a top plan view of the security light fixture of  FIG. 1 ; 
         FIG. 6  is a bottom view of the security light fixture of  FIG. 1 ; 
         FIG. 7  is a rear perspective view of the security light fixture of  FIG. 1 ; 
         FIG. 8  is a front perspective view of the security light fixture of  FIG. 1 ; 
         FIG. 9  is a front perspective view of the security light fixture of  FIG. 1 , in a mode for interconnecting with an electrical conduit; 
         FIG. 10  is a front perspective view of the security light fixture of  FIG. 1 , in a mode for interconnecting with an electrical outlet box; and 
         FIG. 11  is a front perspective view of the security light fixture of  FIG. 1  in which the back plate has a different cross-sectional shape than that of the electrical outlet box. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning to the drawings,  FIGS. 1 ,  3 , and  4  are right side, left side, and front elevational views, respectively, of a preferred embodiment area security light fixture  10 . To achieve the largest area of lighting, the area security light fixture is designed with the light source held away from the wall, pole, building or other structure on which it is mounted by a horizontally extending, cantilevered arm  12 . As discussed previously, moving the light source away from the wall, pole, or building thus gives greater light dispersion around a 360° circumference. Consequently, the cantilevered arm  12  plays an important role in facilitating the function of the security light. 
     The horizontal arm  12  usually attaches to a canopy or upper housing  14 . A large housing is needed to contain the electrical components for the light source  18 .  FIG. 6  is a bottom view of the area security light fixture  10 . Beneath the canopy  14  is the transparent or translucent lens  16  covering the light source, and an optional light reflector. The lens  16  is placed beneath the canopy  14  since the security light  10  is mounted high above ground and the light source  18  is intended to project light laterally and downward toward the ground in a wide area. 
     The canopy or upper housing  14  contains the electrical components used to control and power the light source  18 . An optional photocell  58  can be added to automatically control the on/off operation of the light source  18  based on the intensity of the daylight. Control systems for use with the photocell  58  are known in the art. By incorporating the photocell  58  into the operation of the light fixture  10 , a time-of-day timer or an on/off switch is no longer needed. 
     Placing the electrical components in the housing  14  under the canopy is preferable to avoid having to create a space or chamber in the wall or pole to contain the bulky electrical components for the light source  18 . For area security light fixtures, the bulky and heavy electrical components usually include a ballast, a transformer, a starter, and the like. These components are usually needed for metal halide, mercury vapor, high pressure sodium, fluorescent, and sometimes halogen type light sources, such as can be used in conjunction with a security light system. 
     With a glass lens  16 , a metal housing  14 , a glass light source  18 , and large electrical components, the assembled area security light fixture  10  tends to be large and heavy. To secure such mass and weight to a wall, pole, or building in a cantilevered arrangement, the conventional method is to secure the fixture to a wall or other structure with nails, screws or the like, and then electrically interconnect the light to a power source via a metal pipe or conduit. 
     The conduit or metal pipe has been typically used because it is common for area security light fixtures to be placed at outdoor locations where there is no electrical supply. Hence, an electrician must run a power line from an AC source to where the area security light fixture is to be mounted, and the wires are carried in the metal pipe or conduit—for the portions not buried underground—for protection from weather and rodents. As seen in  FIG. 9 , the metal pipe or conduit  22  is then run up the wall or pole where the area security light fixture  10  is to be mounted. Conveniently, the metal pipe  22  is then fitted inside the cantilevered arm  12  of the area security light fixture  10  to help carry the majority of the weight of the fixture. Electrical wires from the conduit  22  can then be connected to the internal electrical components of the area security light fixture  10  to power the light source  18 . A back plate  20  of the area security light fixture  10  may have screw mounting holes  24  enabling the fixture to be further screwed, nailed, or secured to the wall, pole, or the like. 
     Alternatively, as seen in  FIGS. 10-11 , when the area security light fixture  10  is mounted to a wall, pole, or building having a preexisting electrical junction box or J-box or outlet  26 ,  26 ′, there is no conduit for the arm  12  to mount to, and the screws  24  in the back plate  20  are not strong enough to hold the full weight of the light fixture  10  onto the wall, pole, or building. The present invention in various embodiments thus provides an area security light fixture  10  that can be easily mounted to a junction box or outlet, or to a conduit without a junction box or outlet. 
     In one embodiment as seen in  FIGS. 10-11 , the back plate  20  of the area security light fixture  10  includes a reinforced area to receive a threaded nipple or stud  28 . The threaded stud  28  screws into the center of a cross bar  30 , which itself has mounting slots or holes  32  at opposite ends. Preferably, the threaded stud  28  is a hollow tube with a substantial wall thickness for strength and bending stiffness, and is made from steel. 
     The mounting slots or holes  32  of the cross bar  30  allow easy attachment of the cross bar  30  to an electrical junction box or a standard outlet box  26  with machine screws. The slots enable diametrical adjustment of those mounting screws to fit the size of the particular junction box. In order to carry the weight of the area security light fixture, the crossbar  30  is preferably made from hardened steel and may have greater thickness for improved strength. 
     In  FIG. 10 , a recessed or flush type junction box  26  is shown. In  FIG. 11 , a surface mount type junction box  26 ′ is shown. The threaded stud  28  is screwed to the cross bar  30  at one end and the back plate  20  at the other end. A cap nut  40 , wing nut, or the like holds the threaded stud  28  to the back plate  20 . The area security light fixture  10  is thus mounted to the junction box or outlet box  26 ,  26 ′. 
     Also, the typical back plate for an area security light fixture has a cross-sectional shape (a triangle or square typically) that is similar to the cross-sectional shape (a triangle or square) of the arm. However, to adapt the area security light fixture  10  to a junction box  26 ,  26 ′, the back plate  20  is not shaped like the cross-section of the arm  12 , but its shape is selected to cover the junction box  26 ,  26 ′. Since most junction boxes  26 ,  26 ′ have an opening that is round or square, the back plate  20  is preferably a large square shape to completely cover the opening so the interior of the junction box is not exposed to the weather. 
     Electrical wiring  34  carrying power to the light fixture  10  is connected to leads passing through an opening  36  in the back plate  20 . These wiring leads extend along the inside of the arm  12  and originate from the electrical components contained in the housing  14 . 
     As seen in  FIGS. 2A ,  2 B, there is an increased mass attachment boss  38  in the back plate  20  that receives the threaded stud  28 . This reinforced boss  38  ensures that the stud  28  does not accidentally pull out, or the back plate  20  does not warp or distort under the cantilevered weight of the area security light fixture  10 . In the preferred embodiment, the increased mass attachment boss  38  receiving the threaded stud  28  is a reinforced cone surrounding the threaded hole. The cone shaped attachment boss  38  focuses increased mass at the point where there is a large bending moment acting on the back plate  20 . The preferred cone structure can be seen in the cross-sectional view of  FIG. 2B , which is a cross-section taken along line A-A in  FIG. 2A . The increased height of the boss  38  rising above the thickness of the surrounding or adjacent back plate increases the contact area between it and the threaded stud  28  to decrease stress in that area (since stress σ=F/A force over area) and distributes the bending moment along a greater contact length. 
     Further back plate reinforcing structures include optional ribs  42  arranged in a cross-cross or X, and/or a perimeter ring  44 . A paper or rubber gasket, seal, or silicone bead can be added to the perimeter ring  44  to further seal out the environment. Other reinforcing structures known in the art may be used. 
     Moreover, in the preferred embodiment, the arm  12  and back plate  20  of the area security light fixture  10  are formed from cast metal for improved strength. In fact, the back plate  20 , arm  12 , and housing are preferably all cast in one step with one material. Thus, the back plate  20  and arm  12  are integral giving the necessary strength to support the heavy light fixture  10  without the use of a conduit  22 , which conduit  22  when present would be the primary load bearing member. 
     The foregoing features are collectively used to reliably support the greater weight of area security light fixtures. Such fixtures rely on light sources such as metal halide, mercury vapor, high pressure sodium, fluorescent, or halogen that are typically of a great size, require heavy copper wiring and insulation, and with their starter, ballast, transformer, and glass or plastic lens or diffuser result in great weight, which typically range from about 7 to 20 pounds. Given such weights and typical arm lengths and from empirical observations, the bending moment that must be supported at the reinforced attachment boss  38  and supplemental support structures is typically at least about 60 in-lbf. (inch-pounds-force). Depending on the size and type of light source, the bending moment to be supported ranges preferably about 30-300 in.-lbf. and more preferably about 60-180 in.-lbf. 
     As seen in  FIG. 9 , the area security light fixture  10  of the present invention is readily adaptable for mounting to a wall, pole, or building having a conduit  22  supplying the electrical leads in place of a junction box  26 ,  26 ′. As described earlier, the conduit  22  is usually a metal pipe or tube installed by an electrician in an area where there is no electrical power. The conduit  22  holds electrical wiring  34  that carries power to the light fixture  10 , which may be installed at a remote location at the top of a barn, or on a pole in the middle of an open field. 
     In the preferred embodiment, the arm  12  has a removable bottom plate  46  that is held in place by sheet metal screws  56  or the like. There is a punch-out opening  48  in the bottom plate  46 . The punch-out opening  48  is normally covered by a blank, which is pre-scored or partially cut for easy detachment or opening by hammer blow or even finger pressure. The punch-out opening  48  is normally covered if not in use. 
     In  FIG. 9 , the conduit is inserted through the punch-out opening  48 . If the end of the conduit  22  is already threaded, then a nut  52  can be advanced on to those threads to lock the plate  46  to the conduit  22 . If the end of the conduit  22  is not threaded, an adapter  50  with a radial screw  54  is placed over the end as shown in  FIG. 9 . The radial screw  54  is advanced into contact with the conduit  22  locking the two parts together. Since the adapter  50  is threaded, the nut  52  can be advanced over those threads to hold the plate  46  to the conduit  22 . The adapter may also be a self-threading type fitting that cuts into the pipe as it is advanced onto its end. Or the adapter may be a clamp that under its own material springback or under spring bias locks to the end of the conduit. 
     In another alternative embodiment, the tip of the conduit is not threaded, and a clamp is used instead of the nut  52 , which clamp then holds the tip of the conduit  22  to the bottom plate  46 . Such a clamp may be a lock down collar used in the automotive industry to secure the end of a radiator hose. In yet another embodiment, the unthreaded conduit  22  is inserted into the arm  12  where a bracket, ferrule, collar, recess, or the like is formed into the interior of the arm to receive the conduit tip. These structures together with the conduit provide the primary weight bearing capability. 
     Wood screws  24  can then secure the back plate  20  to the wall, pole, or building. Alternatively or in addition, a lag bolt or the like can be inserted through the attachment boss hole  38  in the back plate  20 . This further holds the back plate  20  to the wall, pole, or building. 
     The electrical wiring from the fixture can be connected to the leads in the conduit  22 . Next, the bottom plate  46  is installed back on the arm  12  using the supplied screws  56 , tabs, rivets, or the like. 
     The present invention area security light fixture can therefore be easily adapted in the field for mounting to a junction box or to a conduit. In addition, the present invention system of mounting to a junction box does not interfere with the invention&#39;s system for mounting to a conduit, and vice versa. 
     Further modifications and improvements may additionally be made to the device and method disclosed herein without departing from the scope of the present invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.