Abstract:
The present invention comprises a pivot stud with an axis of rotation in the horizontal plane for use within a visual optical aim light assembly. The axis of rotation of the pivot stud defines an axis of rotation about which the light assembly may be rotated so as to properly aim the visual optical aim light assembly. The pivot stub does not allow rotation about planes other than the horizontal plane. According to one embodiment, the pivot stud comprises a ball and socket of a generally ellipsoid shape.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to automotive forward lighting systems and, more specifically, to pivot stud assemblies within headlamp assemblies designed for visual optical aim (“VOA”). 
     Automotive headlamps must meet numerous governmentally mandated regulations. Many of these regulations are related to defining the area in front of an automobile that must be illuminated and describing the intensity of light with which these areas must be illuminated. Thus, after a headlamp is installed on an automobile, it must be adjusted to properly illuminate the critical area in front of the automobile. For one type of headlamps, this adjustment activity involves aiming the headlamp using a process referred to as VOA. 
     VOA is a method for positioning an installed headlamp so that it is properly aimed for illumination in the area in front of a vehicle. Headlamps known in the art and designed for VOA generally comprise a pair of pivot studs which define an axis of rotation about which the installed VOA headlamp may be moved. Two pivot studs are needed, in part, to ensure that the light assembly is only capable of rotating about the desired axis. After installation, the direction of the light beam emitted by the headlamp is adjusted upwardly or downwardly by using an adjusting mechanism to force rotation of the headlamp about the axis defined by the pivot studs. 
     The need to incorporate two pivot studs to define an axis of rotation in VOA headlamp assemblies presents significant disadvantages. First, the multiple pivot studs contained within VOA headlamps assemblies add cost to the manufacture of VOA headlamps as a result of greater material needs and increased manufacturing steps leading to increased labor expenses. Second, designers of VOA headlamps have to devote time to creating, or finding, space within a VOA light assembly for multiple pivot studs, thus preventing designers from spending their time on more beneficial projects. A third disadvantage of the pivot studs known in the art is that additional equipment, such as an air driver, is normally required to install pivot studs within a VOA light assembly. The use of an air driver increases the cycle time and, by extension, the manufacturing costs of the VOA light assemblies known in the art. 
     It is desirable, therefore, to provide a pivot stud that eliminates the need for multiple pivot studs to define a rotational axis in a VOA light assembly without being susceptible to excessive off axis movement. It is further desired that use of the pivot stud result in reduced manufacturing costs associated with VOA headlamp assemblies. Moreover, it is desired that the pivot stud be simple to incorporate into existing assembly lines without the need for additional tools or equipment. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with the present invention, a single pivot stud assembly is used to define a rotational axis for a VOA light assembly. The pivot stud assembly is generally of the ball and socket type and comprises a joint which allows rotation only about a single axis. According to one embodiment, this is accomplished by providing an ellipsoid ball portion comprising a major axis. The ellipsoid ball is formed such that rotation is allowed about the major axis, thus the major axis defines an axis of rotation. However, excessive movement other than about the major axis is not allowed. According to one embodiment, the pivot stud is connected to the light assembly housing by a keyed socket. 
     The invention provides a pivot stud assembly that eliminates the need for multiple pivot studs to be used so as to define a rotational axis in a VOA light assembly and is not susceptible to excessive off axis movement. Moreover, the pivot stud assembly results in reduced manufacturing costs because multiple pivot studs are not required. Furthermore, the pivot stud assembly is simple to incorporate into existing assembly lines without the need for additional tools or equipment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a light assembly comprising prior art pivot studs. 
         FIG. 2  is a perspective view of a pivot stud assembly in accordance with an exemplary embodiment of the present invention. 
         FIG. 3  is a perspective view of an alternative embodiment of a pivot stud comprising a tubular ball in accordance with the present invention. 
         FIG. 4  is a perspective view of an alternative embodiment of a pivot stud using a tubular ball with a slot in accordance with the present invention. 
         FIG. 5  is a partial cutaway plan view of the pivot stud of  FIG. 4  engaged with a socket according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a perspective view of a light assembly comprising pivot studs known in the art. Reflector  1  is connected to a light assembly housing (not shown) by pivot studs  2  and  3 . Pivot studs  2  and  3  include a ball shaped tip which is held within grips  4  and  5 . Grips  4  and  5  are formed such that pivot studs  2  and  3  fit snugly within grips  4  and  5 , yet the respective ball shaped tips are allowed to rotate within grips  4  and  5 . Accordingly, rotation is allowed about axis P. Rotation of reflector  1  is effected by means for aiming  6 , which is designed to move in a horizontal path, thus forcing reflector  1  to rotate about axis P. 
     FIG.  2 . is a perspective view of an exemplary embodiment of a of pivot stud assembly of the present invention. As shown in  FIG. 1 , pivot stud assembly  10  comprises two members, stud  12  and socket  14 . Stud  12  comprises ellipsoid ball  16  and post  18 . Post  18  in this embodiment is configured as a key so as to fit into socket  30 , which is located within the housing of a light assembly (not shown). Those of skill in the art will recognize that the present invention may be used with any acceptable means of attaching stud  12  to the light assembly, including, but not limited to, the use of threads, or clips, or forming the stud integrally with the light assembly housing. These and other variations are within the scope of the present invention. 
     Continuing now with  FIG. 1 , socket  14  comprises mounting tab  22  and ellipsoid socket portion  24 . Ellipsoid socket portion  24  comprises chamber  26  and a plurality of tabs  28 . Tabs  28  and chamber  26  are fashioned so as to mate with ellipsoidal ball  16 . When mated, ellipsoidal ball  16  is held snugly within chamber  26  by tabs  28 . In this embodiment, a uniformly rounded surface is realized by the round shape of ellipsoidal ball  16  about axis A. Thus, even when ellipsoidal ball  16  is mated with socket  14 , socket  14  is able to be rotated about ellipsoidal ball  16  about axis A. However, because the joint realized by mating ellipsoidal ball  16  with socket  14  is not uniformly rounded about any other axis, movement about any other axis is not allowed. Accordingly, by use of a single pivot stud, a joint is realized which only allows rotation about a single axis. 
     Continuing with a description of socket  14 , mounting tab  22  is used to attach socket  14  to the reflector of a light assembly (not shown). Those of skill in the art will recognize that the present invention may be used with any acceptable means of attaching socket  14  to the reflector of a light assembly, including, but not limited to, the use of threads or clips, or forming the socket integrally with the reflector. These and other variations are within the scope of the present invention. 
     Referring now to  FIG. 3 , a perspective view of an alternative embodiment of a pivot stud according to the present invention is shown. Pivot stud  32  comprises tubular ball  34  and post  36 . Tubular ball  34  is rounded about axis B. Tubular socket portion  38  comprises chamber  40  and a plurality of tabs  42 . Tabs  42  and chamber  40  are fashioned so as to mate with tubular ball  34 . When mated, tubular ball  34  is held snugly within chamber  40  by tabs  42 . In this embodiment, a uniformly rounded surface is realized by the round shape of tubular ball  34  about axis B. Thus, even when tubular ball  34  is mated with socket  38 , socket  38  is able to be rotated about tubular ball  34  about axis B. However, because the joint realized by mating tubular ball  34  with socket  38  is not uniformly rounded about any other axis, movement about any other axis is not allowed. Accordingly, by use of a single pivot stud, a joint is realized which only allows rotation about a single axis. 
     Referring now to  FIG. 4 , a perspective view of a further alternative embodiment of a pivot stud according to the present invention is shown. Pivot stud  44  comprises tubular ball  46  and post  48 . Tubular ball  46  is rounded about axis C. Tubular ball  46  comprises slot  50  which is used in this embodiment to maintain tubular ball  46  snug against socket  52 . This is shown more clearly in reference to FIG.  5 . 
       FIG. 5  is a partial cutaway plan view pivot stud  44  engaged with socket  52 . Socket  52  comprises tabs  54  which are sized such that when compressed together, they fit within slot  50  of tubular ball  46 . Tabs  54  are constructed of resilient material as is well known in the art, such that once inserted into slot  50 , they uncompress, and engage tubular ball  46  so that tubular ball  46  and socket  52  are held in a position close to each other. If desired, a plurality of slots and tabs may be used to provide additional rigidity to the mated pivot stud assembly. Those of skill in the art will recognize that a variety of joints may be used in practicing the present invention. By way of example, but not of limitation, it may be desired to fashion the pivot stud assembly with axles and wheels. The salient characteristic, is that the joint allows rotation only about a single axis. 
     Returning to  FIG. 4 , a uniformly rounded surface is realized by the round shape of tubular ball  46  about axis C. Thus, when tubular ball  46  is mated with socket  52 , socket  52  is able to be rotated about tubular ball  46  about axis C. However, because the joint realized by mating tubular ball  46  with socket  52  is not uniformly rounded about any other axis, movement about any other axis is not allowed. 
     Those of skill in the art will recognize that a pivot stud assembly according to the present invention eliminates the need for multiple pivot studs to define a rotational axis in a VOA light assembly while eliminating excessive off axis movement. Moreover, a pivot stud according to the present invention reduces manufacturing costs associated with VOA headlamp assemblies by reducing the number of parts required as well as by reducing the number of manufacturing steps involved in attaching the VOA pivot stud assembly. Finally the pivot stud assembly is easily incorporated into existing assembly lines without the need for additional tools or equipment. 
     While the present invention has been described in detail with reference to certain exemplary embodiments thereof, such are offered by way of non-limiting example of the invention, as other versions are possible. By way of example, but not of limitation, in certain applications it may be desired to attach the socket to the light assembly housing and to attach the pivot stud to the reflector. It is anticipated that a variety of other modifications and changes will be apparent to those having ordinary skill in the art and that such modifications and changes are intended to be encompassed within the spirit and scope of the invention as defined by the following claims.