Patent Publication Number: US-2006013011-A1

Title: Glare prevention feature

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      The present application is a divisional application of U.S. patent application Ser. No. 10/633,900 filed Aug. 4, 2003. 
    
    
     BACKGROUND OF THE INVENTION  
      Automotive forward lamp assemblies have been modified over the years to decrease the overall mass of the assemblies in order to increase the safety and the gas mileage of automobiles. Most conventional automotive forward lamp assemblies require a large amount of mass concentration at the front of the vehicle. For example, a typical headlamp and fog lamp assembly will comprise a housing with a reflector, at least one filament bulb, a plurality of electrical wires and a lens. This construction results in a large mass concentration located at the front of the vehicle. In the event of a vehicular accident, a large mass concentration at the front of the vehicle is undesirable because it can result in increased damage and increased injuries. This is especially problematic in the event an automobile collides with a pedestrian.  
      In an effort to reduce the mass of automotive front lighting systems, designers have begun using thermoplastic materials to construct the reflector for headlamp and fog lamp assemblies. Thermoplastic reflectors have the advantage of having less mass than other types of reflectors. Thus, thermoplastic reflectors reduce the overall weight of the lamp assembly. Unfortunately, thermoplastic materials have the drawback of creating manufacturing defects in the form of sinks. As used herein, the term “sink” is used to describe a manufacturing defect located on the reflector that forms a pit in the reflector (i.e. an indentation, a recess and/or a concave surface). A sink causes a large amount of glare to be emitted from the lamp assembly because the defect reflects light in such a manner that a large amount of light is concentrated over a small angle when light reflects from the sink. Concentration of light over a small angle can result in unwanted glare or bright spots in the beam pattern. Thus, sinks are detrimental to the optical performance of an automotive lamp assembly because they cause the lamp assembly to emit a large amount of glare. Sinks occur frequently in the manufacturing of headlamp reflectors because of the thick sections required to form the reflector. For example, a sink normally forms around the socket hole of the reflector. While this is an example of a normal location of a sink, sinks of all shapes and sizes are also prone to appear in other portions of the reflector. In order to use thermoplastic reflectors to manufacture headlamp assemblies, designers of headlamp assemblies are faced with overcoming the glare problems associated with sinks.  
      Accordingly, it is desirable to have an automotive forward lamp assembly that would allow for the use of a thermoplastic reflector without having the large amount of glare resulting from a sink in the thermoplastic reflector. Specifically, it is desirable to develop a design feature that can eliminate the optical problems caused by sinks on thermoplastic reflectors.  
     BRIEF SUMMARY OF THE INVENTION  
      In order to prevent a sink from forming on a reflector, one exemplary embodiment of the subject invention comprises a automotive front lamp assembly with a reflector that has at least one glare prevention feature where normally a sink would form. The glare prevention feature of this embodiment comprises a convex reflective surface that has a relatively sharp radius. The term “sharp radius” defines a convex surface with a relatively small radius such that the convex surface forms an arc that adequately disperses light. While light from a concave reflective surface, as is common with the sinks discussed herein, will tend to concentrate along a particular axis, light reflected from a convex reflective surface will tend to dissipate in different directions. The convex surface can be a convex rib with a sharp radius or a half-sphere with a sharp radius. The sharp radii of these two embodiments allow these two glare prevention features to spread out the light that strikes its surface over a large area in order to prevent glare from being emitted from the lamp assembly. In another embodiment of the subject invention, the glare prevention feature comprises a rib with a substantially perpendicular surface and an angled or curved surface. This embodiment prevents glare by redirecting most of the light that strikes its surfaces so that it is not emitted out of the front lamp assembly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an exploded front view of an exemplary headlamp assembly of the subject invention;  
       FIG. 2  is a cross-sectional view of the reflector of the exemplary headlamp assembly of  FIG. 1  along line A-A;  
       FIG. 3  is a cross-sectional view of the reflector of the exemplary headlamp assembly of  FIG. 1  along line C-C without the glare prevention feature;  
       FIG. 4  is a cross-sectional view of the reflector of the exemplary headlamp assembly of  FIG. 1  along line C-C with the glare prevention feature;  
       FIG. 5  is a front view of a reflector of an exemplary fog lamp assembly of the subject invention without a lens and without a light source;  
       FIG. 6  is a cross-sectional view of the reflector of  FIG. 5  along line B-B;  
       FIG. 7  is a front view of another exemplary embodiment of the subject invention without a lens and a light source;  
       FIG. 8  is a front view of another exemplary embodiment of the subject invention without a lens and a light source;  
       FIG. 9  is a cross-sectional view of the glare prevention feature along line D-D of  FIG. 8 ;  
       FIG. 10  is a front view of another exemplary embodiment of the subject invention without a lens and a light source; and  
       FIG. 11  is a cross-sectional view of the glare prevention feature along line E-E of  FIG. 10 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIG. 1  shows an exploded view of an exemplary embodiment of an automotive lamp assembly that utilizes a glare prevention feature. As shown in  FIG. 1 , the exemplary embodiment comprises automotive front lamp assembly  45 . Front lamp assembly  45  comprises a lens  20  connected to a lamp housing  25  by means well known in the art. For example, an adhesive/sealant can be placed on either lamp housing  25  or lens  20  in order to join them together. Lamp housing  25  contains a reflector  50 . In this embodiment, reflector  50  comprises a thermoplastic reflector having a socket hole  40  that accepts and holds a light source  30 . Reflector  50  is mounted within lamp housing  25  by means well known in the art. For example, an adhesive can be used to mount the reflector to the lamp housing or the reflector can be snapped into the lamp housing. A glare prevention feature  35  is located on reflector  50 . As described in more detail below, glare prevention feature  35  is a thickened portion of the reflector that is formed on the reflector to prevent, at least in part, the formation of a sink and/or to fill or partially fill a recessed area on the reflector where a sink exists. While reflector  50  is a thermoplastic reflector in this embodiment, it will be appreciated by one skilled in the art that the reflector can comprise any number of reflectors known in the art.  
       FIG. 2  is a cross-sectional view of front lamp assembly  45  along line A-A of  FIG. 1 . As shown in  FIG. 2 , reflector  50  has a thick section  60  around socket hole  40  and glare prevention feature  35  located in front of the thick section. If glare prevention feature was not present, a sink  55  would form in front of thick section  60 . Glare prevention feature  35  is molded in the place where sink  55  would form (shown by dotted line in  FIG. 2 ) in order to prevent the formation of the sink and the associated glare problems therewith. Glare prevention feature  35  is a rib  34  with a convex surface  36  that has a sharp radius. The sharp radius of glare prevention feature  35  causes light to spread out over a very large area and reduces the intensity of any light that strikes and reflects off of its surface. This sharp radius prevents glare by preventing light from hitting the convex surface of sink  55  and being reflected off of sink  55  over a small angle. Thus, a designer of front lamp assemblies can prevent the glare caused by sink  55  by molding glare prevention feature  35  in the place where the sink would form.  
      Glare prevention feature  35  forms and becomes part of reflector  50  during the manufacture of the reflector. Reflector  50  is manufactured by an injection molding process well known in the art. A designer can determine where sink  55  is located by molding a first reflector with an injection molding tool. The first reflector will not have glare prevention feature  35 .  FIG. 3  shows a cross-sectional view of front lamp assembly  45  along line C-C of  FIG. 1  without glare prevention feature  35  included in the lamp assembly. As shown in  FIG. 3 , sink  55  is located in front of thick section  60  of reflector  50 . Instead of molding a first reflector, a designer could predict where the sink would be located by analyzing the design (i.e. a part drawing) of the reflector. The sink will be located in front of the thick section. Once the location and size of sink  55  is determined, a designer can create glare prevention feature  35  by cutting into the injection molding tool the desired shape and size of the glare prevention feature at the location where sink  55  appears. The designer can then injection mold a reflector with the altered injection molding tool and glare prevention feature  35  will be molded in the place where sink  55  would have formed.  
       FIG. 4  shows a cross-sectional view of front lamp assembly with glare prevention feature  35  along line C-C of  FIG. 1 . As shown in  FIG. 4 , glare prevention feature  35  is molded in the place where sink  55  (shown by the dotted line) would form on reflector  50 . In this manner, a designer can prevent sink  55  from forming by molding glare prevention feature  35  in the same location. Glare prevention feature  35  will prevent glare from being emitted from the front lamp assembly. It will be appreciated by one skilled in the art that other methods of creating the glare prevention feature can be utilized to manufacture the subject invention. For example, the designer could physically cover any sink formed on the reflector with the glare prevention feature instead of causing the glare prevention feature to be molded where the sink would normally form. Further, while the glare prevention feature comprises the same material used to create the reflector in this embodiment, it will be appreciated by one skilled in the art that various other materials can be used to manufacture the glare prevention feature.  
      Glare prevention feature  35  does not have to be molded in a way that prevents the entire sink  55  from forming. While preventing all of the formation of sink  55  is necessary to prevent all glare produced by the sink, it may be desirable for a designer to reduce the glare instead of entirely eliminating it.  FIG. 5  shows a front view of another exemplary embodiment of the subject invention without its light source and its lens. As shown in  FIG. 5 , the exemplary embodiment comprises fog lamp assembly  65  with reflector  50  and lamp housing  25 . Reflector  50  has socket hole  40  located in the center of the reflector and glare prevention feature  35  located on the reflector.  FIG. 6  shows a cross-sectional view of fog lamp assembly  65  along line B-B of  FIG. 5 . As shown in  FIGS. 5 and 6 , glare prevention feature  35  only prevents the formation of a portion of sink  55 . By partially preventing the formation of sink  55 , the glare can be reduced to meet the desired lighting requirements for the particular automotive front lamp assembly being created.  
      Glare prevention feature  35  can be located anywhere on reflector  50  and can be any shape and size necessary to prevent the formation of any number of sinks  55 .  FIG. 7  shows a front view of automotive front lamp assembly  70  without its lens and its light source. As shown in  FIG. 7 , automotive front lamp assembly  70  comprises reflector  50  and lamp housing  25 . Reflector  50  has socket hole  40  in the center of the reflector and plurality of glare prevention features  35  located on the reflector. Each of the plurality of glare prevention features  35  can be small in size and located anywhere on reflector  50  in order to prevent the formation of any sink  55  on the reflector. It will be appreciated by one skilled in the art that the glare prevention feature can comprise many different shapes and designs in order to prevent the formation of the sink or sinks on the reflector.  
       FIG. 8  shows another exemplary embodiment of the subject invention without its lens and its light source. As shown in  FIG. 8 , this exemplary embodiment comprises front lamp assembly  75  having reflector  50  and lamp housing  25 . Reflector  50  has socket hole  40  located in the center of the reflector and plurality of glare prevention features  35  located on its surface. In this embodiment, each of the plurality of glare prevention features  35  comprises a half-sphere with a sharp radius. Plurality of glare prevention features  35  prevent the formation of sink  55  by being molded on reflector  50  where the sink would form.  FIG. 9  shows a cross sectional view along line D-D of  FIG. 8  of one of the plurality of glare prevention features  35  on reflector  50 . As shown in  FIG. 9 , each individual glare prevention feature  35  forms a convex surface where sink  55  (shown by dotted line) would have been located. As already described, this prevents glare by spreading any light that strikes the convex surface over a large area.  
      Glare prevention feature  35  can also comprise a rib that redirects the light into a non-reflective surface such as the sidewall or the floor of lamp housing  25 .  FIG. 10  shows another exemplary embodiment of the subject invention without its lens and its light source. The exemplary embodiment comprises front lamp assembly  80  having lamp housing  25  and reflector  50 . Reflector  50  has socket hole  40  located in the center of the reflector and glare prevention feature  35  located on its surface.  FIG. 11  shows a cross sectional view along line E-E of  FIG. 10  of glare prevention feature  35 . As shown in  FIG. 11 , glare prevention feature  35  of this embodiment comprises a rib with a substantially perpendicular surface  82  and a curved surface  84 . Substantially perpendicular surface  82  is substantially perpendicular to reflector  50 . In this embodiment, glare prevention feature  35  is located where sink  55  (shown by dotted line) would have formed. As a result, most of the light that hits the glare prevention feature&#39;s surface will be redirected into a non-reflective surface, such as the side-wall or floor of lamp housing  25 . Thus, glare prevention feature  35  prevents glare by redirecting the light in a manner that does not allow it to pass out of lens  20  (not pictured). While glare prevention feature comprises curved surface  84 , it will be appreciated by one skilled in the art that the surface can be angled in such a way to cause the light to be redirected in the desired manner. It will also be appreciated that glare prevention feature  35  could also redirect the light into a reflective surface that either spreads the light out so that it does not cause glare or into a reflective surface that will cause the light to continuously be reflected until it dissipates.  
      While the subject invention has been described in considerable detail with references to particular embodiments thereof, such is offered by way of non-limiting examples of the invention as many other versions are possible. For example, one could cover a sink located on a reflector with a glare prevention feature instead of molding the glare prevention feature where the sink would normally be. The sink could be filled with an epoxy to form a convex surface over the sink and then the epoxy surface could be covered with a reflective coating so that light that hits the glare prevention feature will be reflected over a large angle. 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 pending claims.