Abstract:
A projector lamp for a vehicle headlamp and method for continuously forming the same, which lamp is formed from one piece of sheet metal and includes a cylindrical lens holder and a cup shaped reflector for reflecting light from a vehicle bulb toward the cylindrical lens holder. Integral tabs formed from and extending inwardly from the cylindrical lens holder secure an optical lens within the cylindrical lens holder.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority from U.S. Patent Application Ser. No. 61/093,094, filed Aug. 29, 2008, the entire subject matter of which is incorporated herein by reference 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a vehicle lamp assembly, and more specific to a projection style lamp which is a component of a lamp assembly, but is a single material contiguous design to reduce weight and improve manufacturing efficiency. 
         [0003]    Conventional projector style headlamps consist of multiple components which are assembled together by various means such as resistance welding, screws, fasteners and friction stir welding. The components include a light source, a concave reflector shell for reflecting the light source image, and an optic lens for redistributing the reflected light. In some instances the headlamp is required to have an additional flat plate located between light source and the optic lens to shade portions of the light output from exiting the reflector. Additionally, some form of bracket or other means is necessary to hold the optic lens in the proper location relative to the reflector and light source. One such assembly is described in U.S. Pat. No. 4,857,794. 
         [0004]    The components of such a lamp assembly or projector lamp are comprised from various materials, including steel, aluminum, plastic and powdered metal. The manufacturing methods and assembly techniques vary widely and include die casting, metal stamping, injection molding, forging, riveting, welding and screwing. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The present application is for a vehicle projector lamp or lamp assembly which can be manufactured as one piece using a series of multiple forming operations or a line die operation, or, preferably, a progressive die capable of producing a single stamping which provides the structure of the projector lamp and a method for forming the lamp. The progressive die used to manufacture the lamp consists of multiple stations which sequentially form the lamp stamping which has multiple components of the conventional assembly integrated into a single contiguous component. The major features formed in the tool are a drawn cup for a reflector, a drawn or formed cylinder to hold the optic lens (lens holder), a shield or shade plate which provides a horizontal illumination cutoff line and various locking tabs and support features for final assembly. 
         [0006]    In order to achieve the required reflectivity for optical performance the component may undergo a coating operation to improve the specular or spectral reflectivity of the interior surface of the reflector. The conventional methods of coating in this regard include a base coat which serves to smooth out the rough surface of the steel and provide improved specular reflectance. The area is then coated with a thin film of a material with high spectral reflectance such as Aluminum or Silver. Alternately, a material with high spectral reflectivity such as Aluminum can be used to form the component. In this instance the interior surface of the reflector may undergo manual or electrochemical polishing to improve specular reflectivity. One such commercial electrochemical process is known as Brytal electropolishing. 
         [0007]    The lamp may also undergo swaging, staking or welding operations to fold the stamping up and secure the various regions together. These operations may take place in the progressive forming tool, or in a secondary operation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0008]      FIG. 1  shows the top and side views of the sequence of events at multiple numbered stations for progressively forming the assembly from a single piece of metal; 
           [0009]      FIG. 2  shows a view of the lamp assembly in the stage of forming when the spring tabs are formed in the lens holder to retain the optic lens; 
           [0010]      FIG. 3  shows the front and side view of three lamp assemblies stacked in preparation for a secondary coating operation; 
           [0011]      FIG. 4  shows a top, side and isometric view of the lamp assembly with the bulb holder and shade plate integrated; 
           [0012]      FIG. 5  shows a top, side and isometric view of the lamp assembly with only the lens holder integrated, and not the bulb holder or shade plate; 
           [0013]      FIG. 6  shows a top, side and isometric view of the lamp assembly with the lens holder and shade plate integrated, omitting the bulb holder; 
           [0014]      FIG. 7  shows a cross sectional view of the lamp assembly in  FIG. 4 ; and 
           [0015]      FIG. 8  shows a cut away view of the lamp assembly having a lens held within the lamp assembly. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    Projection style headlamps have gained prevalence in recent years due to their improved light output and distribution on a roadway setting. The conventional designs are comprised of multiple components (e.g. a reflector, a lens holder, a bulb holder and a shade plate). These components are formed separately from steel sheets, made as individual die castings or powdered metal. The components are then assembled in one or more assembly operations. In  FIG. 1 , a metal, such as steel, blank  12  is indicated in station  1 . The blank  12  is comprised of two substantially circular regions with rectangular ends  14 ,  16  connected with a strip  18  as shown. Subsequent forming operations will result in the creation of a functional projector lamp  10  structure from this single blank  12 . In the forming station labeled  2  in  FIG. 1 , a reflector  24  is drawn into the area marked (a) and the lens holder  22  is drawn into the area marked (b). In the third station, the area of the blank  12  marked (c) is trimmed, and 2 holes  26   a,    26   b  are pierced and extruded downward. A hole having a central axis is cut in the bottom of the reflector  24  to allow bulb access. Area (c) will act as a connection point to the opposite side of the blank  16  once the lamp assembly  10  is fully formed. Four (4) tabs  28  are also formed in the wall  30  of the shell  29  which forms the lens holder  24 . These tabs  28  are formed, for example, in a lancing operation so that the tabs extend inward towards the center of the shell wall  30  as shown in  FIG. 2 . 
         [0017]    In the station marked  4 , the opposite side of the blank  12  is trimmed to create the shield or shade plate  34 . Four (4) holes  36   a,    36   b,    36   c,    36   d  are also formed or pierced at this station  4 , which holes will align with the  2  holes  26   a,    26   b  formed at station  3  once the lamp assembly  10  is more fully formed. Additionally, station  4  includes a forming operation for the area marked (d), in which a portion  27  of the area containing holes  26   a,    26   b  is bent downward 90 degrees, as best seen in  FIG. 3 . The flange area  40  of the reflector  24  is also trimmed to create mounting surfaces  42  for installation in a vehicle. In station  5 , a hole  38  having a central axis is cut in the bottom of the shell  29  which forms the lens holder  24  to allow the convex surface C of the optical lens L to protrude from the cylindrical shell  29 . 
         [0018]    At this point the major features of the lamp  10  are formed and the lens holder  22  side of the blank  12  is bent downward at an angle, as in Stations  6  and  7 . This operation is useful to allow the blanks  12  to be placed or supported on a rack for a subsequent metallization or electropolishing operation. The resulting orientation of  3  lamp assemblies  10  is shown in  FIG. 3 . This orientation maximizes the number of lamps  10  which can fit on a rack and improves the efficiency of such an operations. In the instance where the lamp  10  is not required to go through a secondary operation (e.g. manual polishing of high purity aluminum) this forming operation may be eliminated. 
         [0019]    Once the interior surface  23  of the reflector  22  is properly prepared to meet reflectivity requirements, the lamp  10  is formed into its final configuration. One such forming sequence is shown in  FIG. 1 , at stations  7  through  12 . In station  7 , the shade plate  34  is folded upward to a 90 degree angle. In station  8 , the lens holder  22  is folded back up into its original flat position. In station  9 , the leg or bent portion  27  adjacent to the lens holder  22  is formed up 90 degrees. In station  10 , the lens holder shell  29  is bent 90 degrees upward along the strip  18  connecting the lens holder  22  to the reflector  24 . In station  11 , the shade plate  34  is bent 90 degrees to lay flat against the reflector flange  25 . In station  12 , the lens holder  22  is bent at 90 degrees at the reflector  24  and the strip  18  connecting to the lens holder  22 . At this point in the process a connection is made to interconnect the two holes  26   a,    26   b  formed in station  3  with the four holes  36   a,    36   b,    36   c,    36   d  formed in station  4 , which are now aligned in a vertical stack.  FIG. 7  shows a cross section of this area. The extrusions  49  can then be formed to secure the lamp  10  in position, and also with openings  45  to enable additional fastenings. Such additional securing elements such as threaded fasteners, rivets, friction stirring or electrical resistance spot welds may be used in addition to or in place of the extrusion connection method. The optic lens and bulb, as shown in  FIG. 8 , can be installed within the lamp  10  after assembly is completed or at some other point between stations  7  and  12 . 
         [0020]    In the case of a projector lamp  10  made to produce a high beam or fog lamp beam pattern, the shade plate  34  in  FIG. 1 , may be omitted. Additionally, the diameter of any desired bulb holder may require the bottom of the reflector  24  to have an opening that makes the peripheral surface area insufficient to achieve photometric prescription requirements for the vehicle headlamp. This area is indicated as (a) in  FIG. 4 . Two alternatives are presented here to alleviate this situation. In the first instance the projector lamp assembly  10  may be produced without integrating the bulb holder or socket. This alternate part is shown in  FIG. 5 . Additionally, the projector lamp  10  may be formed for a low beam without a bulb socket but with the shade plate  34  as shown in  FIG. 6 . 
         [0021]    An alternative solution to removing the bulb holder is to perform a necking operation in the area (a) of  FIG. 4 . This involves the tapering of the reflector down towards the bulb holder in a way that reduces the diameter of the opening formed by the draw of the bulb holder cylinder. U.S. Pat. No. 5,469,729 describes such a necking operation; however this or many other methods of reducing this diameter are known to those skilled in the art of metal forming and may be employed. 
         [0022]    Alternately, the projector lamp  10  may be formed by deep drawing a single shell. The bottom of the shell functions as the reflector. Spring tabs are formed in a similar manner as described above along the top perimeter of the shell. A hole having a central axis is cut in the bottom of the cylinder to allow bulb installation and the rim of the shell is trimmed and formed to secure the optic lens against the spring tabs. Additionally a rectangular shaped piece is cut from the wall of the cylinder and bent downward at a 90 degree angle. This will form the required horizontal shield for the required low beam cutoff line, which enables proper photometric operation of the vehicle headlamp. Other areas of the side wall of the shell may be removed through piercing operations to prevent unwanted light reflection and reduce component weight. 
         [0023]    The result of the manufacturing method described here is a final projector lamp  10  with one coating process, one assembly process and one stamping process/tool formed from one steel blank  12 . Compared with the conventional systems with up to six separate stampings formed from six separate metal sheets, multiple assembly and coating processes, the present method and lamp design provides a novel and economically beneficial product and process, both in material usage, product weight, product assembly and reduced tooling costs. 
         [0024]    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. 
         [0025]    The use of the terms “a” and “an” and “the” and similar references 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. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. 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. 
         [0026]    Embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.