Abstract:
A component assembly includes a first part having a transparent section. The first part defines an outer surface. A second part is fixedly secured to the first part at a portion of the transparent section. The first and second parts create a connecting seam through the portion of the transparent section. An optically covering surface extends between the connecting seam and the outer surface of the first part to cover the connecting seam from view from the outer surface.

Description:
BACKGROUND ART 
     1. Field of the Invention 
     The invention relates to a multipart component having a connecting seam. More particularly, the invention relates to the multipart component for a lighting unit and a method for manufacturing same. 
     2. Description of the Related Art 
     For multipart components having a connecting seam between a transparent first part and a second part, a known problem is that the connecting seam can be seen by an observer. If the transparent part represents a visible side of the component in accordance with requirements, the connecting seam is often objectionable and detracts from the overall appearance of the component. 
     For lighting units of motor vehicles, which represent an example of such multipart components, such a connecting seam between an external lamp, i.e., light diffuser, and the reflector part is particularly objectionable in the lighting unit, since the high-quality appearance of the lighting unit is impaired by a non-uniform connecting seam in the field of vision of the observer. This is particularly unacceptable when the lighting unit is a part of an expensive product such as a motor vehicle. The circumferential connecting seam is located in the edge region of the lighting unit. To laminate the connecting seam, a matching strip-like cover made of a covering material, a plastic layer, for example, is therefore applied to the exterior of the transparent cover. This is laborious, and this cover may be damaged after the lighting unit or vehicle has been used for some time. 
     SUMMARY OF THE INVENTION 
     A component assembly includes a first part having a transparent section. The first part defines an outer surface. A second part is fixedly secured to the first part at a portion of the transparent section. The first and second parts create a connecting seam through the portion of the transparent section. An optically covering surface extends between the connecting seam and the outer surface of the first part to cover the connecting seam from view from the outer surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a cross-sectional side view of one embodiment of the invention incorporated into a component having a connecting seam; and 
         FIG. 2  is a cross-sectional side view of the invention incorporated into an automotive lighting unit. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the Figures, elements that basically remain the same or have the same function are designated by identical reference numerals.  FIG. 1  schematically illustrates a multipart component  10  having a connecting seam  18  between a transparent first part  11  and a second part  17 . With its outer surface  13 , the transparent first part  11  forms a visible side  23  in accordance with specified requirements of the multipart component  10 . The connecting seam  18  is located in a region  24  that is visible through the outer surface  13 . The transparent first part  11  has a projection  22  at which the connecting seam  18  is situated on the outer end face side. 
     In a multipart component according to the invention, an optically covering surface  23  is provided between a connecting seam  18 , situated between a transparent section of the first part  11  and a second part  17 , and an outer surface  13  of the transparent part  11  (the first part  11 ), which covers, at least in places, the connecting seam  18  from a visible side  23  of the multipart component  10 . Without the covering surface  15 , the connecting seam  18  would be visible from the outside. The optically covering surface  15  is located inside the transparent first part  11 , and thus in a manner of speaking is encapsulated by the body thereof and is completely protected from external influences that could act on the first part  11  from the outside. The optically covering surface  15  is inserted into the transparent first part  11  during the manufacturing process, so that laborious refinishing of the final installed component is omitted. The term “optically covering” need not necessarily mean complete opaqueness, provided that direct visibility of the connecting seam  18  is at least significantly reduced. Optionally, in a similar manner the second part may also be provided with an optically covering surface  15 . This is advantageous when the second part  17  of the multipart component  10  also has a transparent design at one or more possible seam locations and is to form a visible side, which in accordance with requirements, is accessible to a possible observer, for example, a case that is at least partially transparent. The first  11  and second  17  parts preferably represent constituents of a housing for the component  10 . Other parts of the component may also be provided with such an optically covering surface. 
     The transparent first part  11  is formed from a first partial region  12  facing the connecting seam  18  and a second partial region  14  facing the outer surface  13 , the partial regions  12 ,  14  abutting one another at an interface  16 . The interface  16  must not be noticeable. For a component  10  designed as an injection-molded part, the interface  16  disappears after the second partial region  14  is attached. 
     An optically covering surface  15  is provided between the connecting seam  18  and the outer surface  13  which covers, at least in places, the connecting seam  18  from the visible side  23 . The component  10  is adjacent to, for example, a body  19  such as a wall of a mounting opening, and overlaps same on the edge side at an overlap region  20 . 
     The optically covering surface  15  is provided between the first and second partial regions  12 ,  14 , and preferably is designed as a vapor deposition layer. The surface  15  may have an opaque or also a semitransparent design. The surface  15  covers the connecting seam  18  in the direction of sight  21 . In the embodiment, the surface  15  is so wide that it also partially covers the overlap region  20  of the component  10  with the body  19 . 
     According to the invention, for the multipart component  10 , the first partial region  12  is formed, the optically covering surface  15  is provided there in places, and then the second partial region  14  is provided which encapsulates the surface  15 . The optically covering surface  15  may be applied to the first partial region  12  using the PVD and/or CVD method, or by other suitable methods such as spraying, placement, imprinting, in particular pad printing, or stamping, in particular hot stamping. 
       FIG. 2  shows a preferred lighting unit  30  as an example of a multipart component. The lighting unit  30  represents a vehicle lighting unit. A transparent first part  31  is designed as a light diffuser having an outer side  33 , and covers a second part  37  comprising a series of reflector regions  28   a ,  28   b ,  28   c ,  28   d  having associated light sources  25   a ,  25   b ,  25   c ,  25   d . The light diffuser represents a typical visible side  43  of the lighting unit  30 . The reflector regions  28   a ,  28   b ,  28   c ,  28   d  are sealed off with respect to the transparent first part  31  by elements  26   a ,  26   b ,  26   c ,  26   d , which influence the light emitted from the light sources  25   a ,  25   b ,  25   c ,  25   d  in a desired manner known as such. The transparent first part  31  preferably is formed from polymethylmethacrylate (PMMA) or polymethylmethacrylimide (PMMI). 
     A connecting seam  38  is provided between the transparent first part  31  and the second part  37 . In the installed state, the second part  37  is usually located inside a vehicle body and is not visible from the outside, whereas the transparent first part  37  is located on a visible side  34  of the lighting unit  30 . In the direction of sight  41  on the edge side, an optically covering surface  35  is provided on the first part  31  circumferential to a visible region  44 , between a first partial region  32  facing the connecting seam  38  and a second, outwardly facing partial region  34  of the first transparent part. It is seen that in this case, the optically covering surface  35  has a very unobtrusive and narrow design to cover the unattractive connecting seam  38 , typically a weld seam. In the direction of sight  41 , the connecting seam  38  in each case is covered in a region  44 , visible in principle to an observer, by means of the optically covering surface  35 . 
     In the manufacture of the lighting unit  30 , the transparent first part  31  designed as a light diffuser may be produced as an injection-molded part in an injection mold, whereby initially the first partial region  32  is injection-molded by introducing PMMA or PMMI, for example, into the injection mold. A preform is then formed which is removed from the injection mold. The optically covering surface  35  is then applied to the first partial region  32 , in particular by vapor deposition or sputtering. If the optically covering surface  35  is produced by such PVD or CVD methods, the areas of the partial region  32  not to be coated are masked by covering with an appropriate shadow mask, or a mask is applied in the form of a photomask, known from photolithography, which is removed after coating with the optically covering surface  35 . After reinsertion into the injection mold the first partial region  32  is insert molded and/or overmolded, thereby forming the second partial region  34 . The transparent first part  31 , which at this point is completely formed, is then securely joined to the second part  37  at the connecting seam  38 . If the second part  37  is made of plastic, the first and second parts  31 ,  37  may be welded together, in particular by friction welding. 
     The invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation. 
     Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.