Abstract:
A ballast housing having a rolled edge lead wire exit for providing protection and strain relief to lead wires extending out from the housing. Grommets are not required in order to provide protection and strain relief to lead wires exiting the housing. The housing includes a lead wire opening having rolled upper and lower edges. The housing includes a lid including the rolled upper edge and a can including the rolled lower edge. The rolled upper edge is vertically aligned with the rolled lower edge but horizontally misaligned with the rolled lower edge. As a result, the rolled upper edge is positioned away from the rolled lower edge a distance that is horizontally shorter than the diameter of the lead wire. Additionally, the lead wire opening has a vertical diameter that is shorter than the diameter of the lead wire.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a Non-Provisional Utility application which claims benefit of co-pending U.S. Provisional Patent Application Ser. No. 60/740,316 filed Nov. 29, 2005, entitled “Rolled Edge Exit for Lead Wires in Metal Ballast Housing,” which is hereby incorporated by reference. 
     All other patents, patent applications, and publications described or discussed herein are also hereby incorporated by reference in their entirety. 
    
    
     A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to ballast housings. More particularly the current invention relates to a ballast housing having a rolled edge lead wire exit. 
     Ballast housings are well known in the art. An example of a typical prior art ballast housing is shown in  FIG. 1 . These housings are normally composed of metal and have lead wire exit holes that are used to feed lead wires from the electronic components inside the ballast housing to external devices, such as an AC power source. Lead wire exit holes typically have sharp edges that can cut or damage lead wires, which are normally insulated for safety and efficiency, extending through the lead wire exit holes. If this occurs, the electronic components inside the ballast housing may malfunction and become unsafe. 
     As seen in  FIGS. 1 and 2 , prior attempts to alleviate these safety and functional problems have included the use of a grommet for strain-relief and protection of wires extending from housings. It is common throughout the ballasts industry to use custom molded grommets made out of soft plastic, rubber or similar material. These grommets are pressed into stamped openings in the housing of the base, or can, of the ballast. Wires, such as lead wires, are then routed through top slits in the grommets, which are then subsequently closed when the housing lid is assembled onto the can. 
     The use of grommets has several disadvantages. For example, the grommets normally must be custom molded to fit each opening in the ballast. Increased labor and material costs are associated with the production and installation of the grommets used in each opening of the ballasts. The required position of the grommets can result in injuries to the assembler by the metal edges on the ballast openings as well as the potential for carpal tunnel syndrome through repeated installation of the grommets. 
     What is needed, then, is a ballast housing that protects and provides strain relief to lead wires exiting the housing and that eliminates the disadvantages associated with existing prior art ballast housings. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, one object of the present invention is to provide a ballast housing that protects and provides strain relief to lead wires exiting the housing. 
     Another object of the present invention is to provide a ballast housing that eliminates the disadvantages associated with existing prior art ballast housings. 
     Still another object of the present invention is to provide a ballast housing that eliminates the need for grommets to protect and provide strain relief for lead wires extending from the housing. 
     These, and other objects, features and advantages of the present invention, which will be readily apparent to those skilled in the art upon reading of the following disclosure, are satisfied by the present invention of a ballast housing having a rolled edge lead wire exit. 
     The housing comprises a lead wire opening that provides compression to, and strain relief for, a lead wire passing through the lead wire opening. The lead wire opening includes a rolled upper edge and rolled lower edge. The rolled upper edge is horizontally misaligned with the rolled lower edge. As a result, the rolled upper edge is positioned away from the rolled lower edge a distance that is horizontally shorter than the diameter of the lead wire. Additionally, the lead wire opening has a vertical distance that is shorter than the diameter of the lead wire. 
     The housing can also include a lid connected to a can. The rolled upper edge can be part of a u-shaped indentation in the lid and the rolled lower edge can be part of a u-shaped indentation in the can. 
     The lid and can of the ballast housing can each be described as having a continuous hem defining a window in the lid and can, respectfully. The lid and can be connected so that the continuous hem in the lid is aligned with and overlaps the continuous hem in the can. The continuous hems in the lid and can compress and provide strain relief for a lead wire passing through the opening formed by the continuous hems. 
     The continuous hem in the lid can be positioned above and vertically aligned with the continuous hem in the can. Additionally, the continuous hem in the lid can be horizontally displaced from the continuous hem in the can by a distance that is shorter than the thickness of the lead wire. 
     In an alternate embodiment, the lid is a plastic lid having a lid end panel and a snap tab, wherein the lid end panel includes an edge having a rounded corner and a strengthening rib. The can includes a can end panel and a snap tab opening, wherein the can end panel includes a u-shaped rolled edge aperture. The plastic lid is connected to the can so that the lid end panel overlaps the can lid panel. When so positioned, the rounded corner and u-shaped rolled edge aperture compress and provide strain relief to a lead wire passing through a lead wire window in the housing. The lead wire window is formed by the rounded corner and the u-shaped rolled edge aperture. The snap tab is engaged by the snap tab opening to facilitate securement of the lid to the can. 
     Also included herein is an improved exit for wires extending from electronic devices, such as ballasts. The ballast includes a top and a container with at least one wire extending from the ballast. The top includes a top internal portion and at least one top wire aperture defined by a top crease, a top edge, and a top engaging surface. The top engaging surface extends from the top crease to the top edge, while the top edge is turned towards the top internal portion. The container includes a container internal portion and at least one container wire aperture defined by a container crease, a container edge, and a container engaging surface. The container engaging surface extends from the container crease to the container edge. The container edge is turned towards the container internal portion. 
     Additionally, the at least one top wire aperture can be vertically and horizontally offset with respect to the at least one container wire aperture when the top is positioned on the container. When so positioned, the top engaging surface and the container engaging surface are in direct contact with the wire and apply a compressive force to the wire positioned in the apertures. The top wire aperture and the container wire aperture can be separated by a vertical and horizontal distance such that the vertical distance is less than the thickness of the wire extending from the ballast. Additionally, the horizontal distance can be less than the thickness of the wire. This relationship facilitates the engaging surfaces being in direct contact with the wire and protects the connection of the wire to the internal elements of the ballast. 
     In one embodiment, the wire apertures are arcuate in shape and the top and container are composed of metal. Alternately, the top and container can be composed of plastic-like material. When composed of plastic-like material, the top can include a biasing closure and at least one support rib positioned proximate to the top wire aperture for support. The biasing closure can engage a closure opening in the container to secure the top to the container. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a partial perspective view of a prior art ballast housing with a grommet positioned beside it. 
         FIG. 2  is a partial perspective view of a prior art ballast housing having multiple grommets and wires extending through the grommets. 
         FIG. 3  is a partial perspective end view of a ballast housing made in accordance with the current disclosure. 
         FIG. 4  is a partial cross sectional view showing detail of a lid and container made in accordance with the current disclosure. 
         FIG. 5  is a partial internal perspective view showing a lid and container made in accordance with the current disclosure. 
         FIG. 6  is a partial internal cross sectional view of an alternate lid and container made in accordance with the current disclosure. 
         FIG. 7  is a partial internal cross sectional view of an alternate lid and container made in accordance with the current disclosure. 
         FIG. 8A  is a partial cross sectional view of a ballast housing in accordance with the current disclosure. 
         FIG. 8B  is a partial cross sectional view of a ballast housing in accordance with the current disclosure. 
         FIG. 8C  is a partial cross sectional view of the ballast housing of  FIG. 8B . 
         FIG. 8D  is a partial perspective view of the ballast housing of  FIG. 8A . 
         FIG. 9A  is a partial cross sectional view of a ballast housing in accordance with the current disclosure. 
         FIG. 9B  is a partial cross sectional view of the ballast housing of  FIG. 9A . 
         FIG. 10A  is a partial cross sectional view of a ballast housing in accordance with the current disclosure. 
         FIG. 10B  is a partial perspective view of the ballast housing of  FIG. 10A . 
         FIG. 10C  is a partial perspective view of the ballast housing of  FIG. 10A . 
         FIG. 10D  is a partial cross sectional view of a ballast housing in accordance with the present invention. 
         FIG. 11  is a partial perspective view of a ballast housing in accordance with the present invention. 
         FIG. 12  is a partial perspective view of a ballast housing in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring generally now to the Figures, a ballast housing is shown and generally designated by the numeral  10 . The ballast housing can include a wire  12 , or wires  13  and  14 , extending from the ballast housing  10 . The wires  13  and  14  or  12  can be combinations of single or double wires known in the art to extend from electronic devices, such as a ballast  100 . The ballast housing  10  includes a lid  16  and a can  18 . In one embodiment, shown in  FIG. 9A , a ballast housing  10  includes a lead wire opening  60  between the lid  16  and the can  18 . The lead wire opening  60  in the housing  10  includes a rolled upper edge  56  and a rolled lower edge  58 . The lead wire  12 , not shown, passes through the lead wire opening  60  between the rolled upper edge  56  and the rolled lower edge  58 . In one embodiment, the rolled upper edge  56  is horizontally misaligned from the rolled lower edge  58  by a horizontal distance  64 , as seen in  FIG. 9A . The horizontal distance  64  is typically less than the diameter of the lead wire  12 . Additionally, the vertical distance  66  between the rolled upper edge  56  and the rolled lower edge  58 , seen in  FIG. 9A , is less than the diameter of the lead wire  12 . In one embodiment, seen in  FIG. 9B , the lead wire opening  60  includes a lead wire opening dimension  72  that is less than the diameter of the lead wire  12 . The lead wire opening  60  may provide both compression to and strain relief for the lead wire  12  passing through the lead wire opening  60 . In one embodiment, the rolled upper edge  56  is part of a u-shaped indentation located on the lid  16 . Similarly, in one embodiment, the lower rolled edge  58  is part of a u-shaped indentation located in the can  18 . 
     The lid  16 , which can also be described as a top  116 , includes a lid wire aperture  20  defined by a lid engaging surface  22 , seen in  FIG. 11 . The lid engaging surface  22  extends from a lid edge  24  to a lid crease  26 , seen in  FIG. 9B . The lid crease  26  can be generally described as being substantially positioned near the start of the curvature of the lid engaging surface  22  from the lid wall  28 , as seen in  FIG. 4 . The lid edge  24  is turned toward the lid internal portion  30 , which can be generally described as the internal cavity formed by the lid walls  28  and the top lid plate  29 . The lid edge  24  can be further turned towards the lid wall  28 , which can also be described as a lid support wall  28 . 
     The can  18 , which can also be described as a container  18 , includes a can internal portion  32 , which can be described as the cavity formed by the can walls  31  and can bottom plate  34 . A can wire aperture  36  is positioned in one of the can walls  31  and is defined by a can crease  38 , can edge  40  and can engaging surface  42 . The can engaging surface  42 , which can also be described as a second curved engaging surface, extends from the can crease  38  to the can edge  40 . The can edge  40  is turned towards the can internal portion  32  and can be further turned towards the can wall  31 , which can also be described as a can support wall  31 . The can crease  38  can be generally described as being substantially positioned near the start of the curvature away from the can wall  31 . 
     In one embodiment, the lid wire aperture  20 , seen in  FIG. 11 , is vertically and horizontally offset with respect to the can wire aperture  36  when the lid  16  is positioned on the can  18 . In this configuration, the lid wire aperture and the can wire aperture  36  apply a compressive force to the wire  12 ,  13 , or  14  positioned within the apertures  20  and  36 . Additionally, in this position the engaging surfaces  22  and  42  are in direct contact with the wire  12 ,  13 , or  14 . The apertures  20  and  36  can be separated by both a horizontal and vertical distance. The thickness of the wire  12 ,  13 , or  14  positioned between the apertures  20  and  36  can be such that the vertical distance between these apertures is less than the thickness of the wire  12 ,  13 , or  14 . Additionally, the horizontal distance between the apertures  20  and  36  can also be less than the thickness of the wire  12 ,  13 , or  14 . This space configuration facilitates the compressive force placed on the wires  12 ,  13 , or  14  by the engaging surfaces  22  and  42 . 
     Referring now to  FIG. 10A , in one embodiment, a ballast  100  includes at least one wire  12  extending from the ballast  100 . The ballast  100  includes a top  116  and a container  106 . The top  116  includes a top wire aperture  108 , shown in  FIG. 10B . The top wire aperture  108  is defined by a top crease  118 , a top edge  120  and a first curved engaging surface  114  extending between the top crease  118  and the top edge  120 . The top edge  120  is bent toward the top internal portion  102 . The container  106  includes a container internal portion  104  and a container wire aperture  110 . The container wire aperture  110  is defined by a container crease  124 , a container edge  126  and a second curved engaging surface  112  extending between the container crease  124  and the container edge  126 . The container edge  126  is generally bent inward toward the container internal portion  104 . In one embodiment, shown in  FIGS. 10A and 10B , the top wire aperture  108  is both vertically and horizontally offset from the container wire aperture  110  when the top  116  is positioned on the container  106 . As such, both the first curved engaging surface  112  and the second curved engaging surface  112  apply a compressive force to the wire  12  positioned in the apertures  108 ,  110 . In one embodiment, the engaging surfaces  114 ,  112  are both in direct contact with the wire  12 . In another embodiment, the wire  12  includes a thickness  70 . The apertures  108 ,  110  are separated by a vertical distance  66  and a horizontal distance  64 , seen in  FIGS. 10C and 10D . In one embodiment, the horizontal distance  64  is less than the thickness  70  of the wire  12 . In another embodiment, both the horizontal distance  64  and the vertical distance  66  are less than the thickness  70  of the wire  12 . Also, in one embodiment, the top  116  and the container  106  are composed of metal. In one embodiment both the lid  16  and can  18  are composed of metal, as shown in  FIGS. 3-4 . The lid  16  and can  18  can be fastened together in conventional manners known in the art. 
     In an alternate embodiment, the lid  15  is composed of plastic as shown in  FIGS. 6-7 . The lid can include a biasing closure  44 , and a support rib  46 . The biasing closure  44  can be shaped and positioned to correspond to a closure opening  48 , positioned on the can  18  to accept the biasing closure  44  to secure the lid  15  to the can  18 . In another embodiment, a ballast  100  includes a top  116  made of plastic and including at least one biasing closure  44  and at least one support rib  46 . The support rib  46  is generally positioned proximate to the top wire aperture  108 . Also, in one embodiment, the container  106  includes at least one closure opening  48 . The closure opening  48  resiliently engages the biasing closure  44  to secure the top  116  to the container  106 . 
     The support rib  46  can be positioned to engage the lid walls  50  and top lid plate  51  of the lid  15  to facilitate support of the lid structure  15 . The support rib  46  can preferably be positioned proximate to the wire aperture  52  to facilitate support thereof. The wire aperture  52  can include a curve engaging surface  54  that interacts with the curve engaging surface  42  of a can  18  to facilitate compression and securement of the wires  12 ,  13 , or  14  positioned in the apertures  52  and  36 . 
     Alternately, the can  18  can also be composed of plastic without substantially deviating from the inventive nature of this disclosure. In one embodiment, shown in  FIG. 8A , a ballast housing  10  includes a plastic lid  15  having a lid end panel  86 . The plastic lid  15  includes a snap tab  84  which resiliently engages a snap tab opening  94 , located on the can  18 , to secure the plastic lid  15  to the can  18 . The lid end panel  86  further includes an edge  74  having a rounded corner  88 . The lid end panel  86  also includes a support rib  46  extending therefrom. Also shown in  FIG. 8A , the can  18  includes a can end panel  92  having a u-shaped rolled edge aperture  96 , seen in  FIG. 8D . The u-shaped rolled edge aperture  96  of the can  18  and the rounded corner  88  of the plastic lid  15  form a lead wire window  98 , shown generally in  FIG. 8C . The lead wire window  98  generally has a dimension  72  smaller than the diameter of the lead wire  12  so that the rounded corner  88  and the u-shaped rolled edge aperture  96  provide compression to the region of the lead wire  12  passing through the lead wire window  98 . As such, the lead wire window  98  also provides mechanical strain relief to the lead wire  12  in the ballast housing  10  by reducing the strain felt by the lead wire  12  positioned inside the ballast housing  10  when force is applied to the region of the lead wire  12  extending outside the ballast housing  10 . In one embodiment, the ballast housing  10  is made of injection molded plastic. In one embodiment, shown in  FIG. 8B , the plastic lid  15  is offset from the can  18  by a horizontal distance  64 . The horizontal distance  64  can be less than the lead wire diameter  62 , seen in  FIG. 8A . 
     The apertures  20  and  36  can also be described as having a rolled edge, which can be generally described as including the engaging surfaces  22  and  42 . The rolled edges can also be described as having a continuous hem positioned in the apertures  20  and  36 . In one embodiment, shown in  FIG. 12 , the ballast housing  10  includes a lid  16  having a first continuous hem  78  defining a first window in the lid  16 . The ballast housing  10  also includes a can  18  having a second continuous hem  80  defining a second window in the can  18 . In one embodiment, the lid  16  is connected to the can  18  and the first continuous hem  78  is aligned with and overlaps the second continuous hem  80 . A lead wire  12 , not shown, passes through the opening  82  defined by the space between the first continuous hem  78  and the second continuous hem  80 . 
     Thus, although there have been described particular embodiments of the present invention of a new and useful Ballast Housing Having Rolled Edge Lead Wire Exit, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.