Abstract:
A headlamp apparatus comprising a cup-shaped reflector comprising a front opening, a rear opening and a valve assembly disposed thereon for allowing air external to said headlamp apparatus to flow into an interior of said headlamp while moisture is prevented from entering into said interior of said headlamp apparatus, a lens secured to said front opening for closing said front opening and defining said interior and exterior of said headlamp apparatus and a socket retention assembly containing a light source disposed within said rear opening.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates generally to headlight constructions, and more particularly to a headlight for automotive vehicles or the like.  
         DISCUSSION OF RELATED ART  
         [0002]    There are basically two different types of headlight constructions for automotive vehicles and similar applications. One of these is the “sealed-beam” type of headlight wherein the reflector and the filament are united in a unit which is discarded in toto when the filament or the envelope becomes damaged. Current sealed beam headlamps use glass for the lens and reflector and the two pieces are hermetically bonded in production. The bulb is also sealed within the lamp. In these sealed-beam headlights the interior of the construction is totally protected against any deleterious ambient influences until and unless the envelope should become damaged in some way. This is advantageous but it is also expensive when the entire unit must eventually be replaced. Furthermore, known sealed beam lamps rely on mechanical components for aiming the beam from the headlamp.  
           [0003]    The other type of headlight construction is the more conventional one. It utilizes a cupped reflector, the open side of which is provided with an opening through which an incandescent bulb is inserted into the interior of the reflector. If damage results to the bulb for any reason, for instance if the filament burns out, the bulb is simply removed through the opening and replaced with a new one.  
           [0004]    The present invention is concerned with the second type of headlight construction, that is the type utilizing a replaceable bulb as opposed to the sealed-beam type of unit.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    One aspect of the present invention regards a headlamp having a cup-shaped reflector with a front opening, a rear opening and a valve assembly. The valve assembly is located on the reflector and allows air external to the headlamp to flow into the interior of the headlamp while moisture is prevented from entering into the interior of the headlamp. The headlamp further includes a lens and a socket retention assembly. The lens is secured to the front opening of the headlamp thereby defining an interior and exterior of the headlamp. The socket retention assembly contains a light source and is disposed within the rear opening of the headlamp.  
           [0006]    Another aspect of the present invention regards a method of operating a headlamp apparatus by turning on a light source within the headlamp apparatus, allowing air to flow within an interior of the headlamp apparatus, and preventing moisture from entering the interior of the headlamp.  
           [0007]    Each aspect of the present invention provides the advantages of a composite style headlamp with a removable light source made of break resistant high impact and high temperature plastic that incorporates all of the optics on the reflector. Further, the headlamp is water resistant. A vent is place on the lamp that allows air external to the headlamp to enter into the interior of the headlamp while preventing moisture from entering.  
           [0008]    Additional aspects and advantages of the present invention will become apparent from the following description and the appended claims when considered with the accompanying drawing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 a side cross-sectional view of an embodiment of a headlamp according to the present invention;  
         [0010]    [0010]FIG. 2 is a front view of the headlamp of FIG. 1;  
         [0011]    [0011]FIG. 3 is a top cross-sectional view of the headlamp FIG. 1; and  
         [0012]    [0012]FIG. 4 is a plan view of the headlamp of FIG. 1.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    Referring to FIG. 1, a composite styled headlamp  100  with a replaceable light source  102  according to the present invention is designed to replace a sealed beam headlamp. As explained previously, the current sealed beam lamps are made from glass which makes the lamp sensitive to in-use breakage. The headlamp  100  uses a high impact (polycarbonate) circular lens  103  that is 20 times more resistant to breakage, such as sold under the trade name “Lexan” by the General Electric Company and typically has a diameter of 7″. A reflector  104  of the headlamp  100  is designed from a high temperature plastic material and has a general shape of a parabolic. Moreover, the optics of the headlamp  100  are incorporated into the reflector  104  to form the shape of the beam emitted from the headlamp  100 . There are no separate optics on the lens  103  at all. The headlamp  100  relies completely on visual/optical aiming. The beam pattern is formed by the headlamp  100  clearly defines a horizontal line so that aiming/adjustment of the headlamp  100  can be achieved by visual or optical methods. The replaceable light source  102  is used in the headlamp  100 , such that, if there is a failure of the light source  102 , only the light source  102  must be replaced. The replaceable light source  102  incorporates its own seal, such that, when it is installed, the complete headlamp  100  is resistant to having water enter into the interior of the headlamp  100 . A “patch” type vent  105  is placed on the headlamp  100  that allows only air to pass through into the interior and not moisture. The vent  105  equalizes the pressure in the headlamp  100  with the outside and reduces the internal stresses in the headlamp  100 . This headlamp  100  is intended to be an exact replacement for the sealed beam lamp describe previously, and uses the exact same hardware for installation.  
         [0014]    [0014]FIG. 1 shows a cup-shaped reflector  104 , which is typically made of a high temperature plastic material, has a front opening  106  and a rear opening  107 . The front opening  106  has a grooved annular portion  108  in which a tongue portion  109  of lens  103  is inserted and secured, usually by being adhesively secured in place. The lens  103  is made of high impact polycarbonate material that is 20 times more resistant to breakage than glass.  
         [0015]    A socket retention assembly  110  containing the light source  102  is disposed within the rear opening  107  of the reflector  104 , such that, terminals  111  of the socket retention assembly  110  extend rearward and outside of the reflector  104 . An annular retainer ring  112  encircles the rear portion of socket retention assembly  110  when it is disposed within the rear opening  107  of reflector  104  for holding and sealing the socket retention assembly  110  within the rear opening  107  of the reflector  104 . The use of the annular retainer ring  112  is known in the art and needs no further discussion here. The light source  102 , typically a bulb, has a filament within it and has connecting portions for electrically connecting the light source  102  to the terminals  111  when the light source  102  is disposed within the socket retention assembly  110 . The light source  102  is sealed within the socket retention assembly  110  by use of an O-ring (not shown) between the socket retention assembly  110  and the light source  102 . Thus, the light source  102  is located in the interior of the reflector  104 .  
         [0016]    Referring to FIG. 1, also located on the inner surface of the reflector  104  is a shield assembly  113 . The shield assembly  113  includes a shield  114  having one end portion  115  formed in the shape of a hemisphere. The base end  116  of the shield  114  is connected to the inner surface of the reflector  104  near the rear opening  107 . A 3×9.5″ pan head screw may be used to connect the shield assembly  113  to the inner surface of the reflector  104 . The shield  114  partially surrounds the light source  102  and performs three distinct functions. First, the hemispherical portion  115  of shield  114  hides the light source  102  thereby increasing the headlamp&#39;s  100  aesthetic value, as generally shown in FIG. 2. The second function of the headlamp  100  is for optical purposes.  
         [0017]    Referring to FIG. 3, the rearmost edge  118  of the hemispherical portion  115  is trimmed so that the light from the light source  102  will not impinge on non-optical surfaces and produce uncontrolled light. The third function of the shield  114  is that the hemispherical portion  115  acts as a heat shield.  
         [0018]    Referring now to FIGS. 1 and 3, in use, the light source  102  may become very hot and the hemispherical portion  115  of the shield  114  will help to absorb and dissipate the heat that would otherwise affect the upper surface of the headlamp  100  or lens  103 . Additionally, there is black coating applied to the inside portion of the hemispherical portion  115  that can significantly reduce reflections inside the shield  114  that might incident the reflector  104  to reflect to unwanted areas. If the shield  114  is not present all three functions will be adversely affected.  
         [0019]    The inner surface of the reflector  104  is coated with a thin film of highly reflective aluminum. It is applied by a process called vacuum metallization. Additionally, a thin coat of a polymer is applied to the surface of the aluminum to prevent oxidation of the surface. This coating is applied just after the metallization process. The reflector  104  is molded from a thermoset plastic material. The reflector  104  is prepared for the aluminum by a base coating of the inner surface to make it very smooth. This coating is applied then cured by using a strong UV light. The reflector  104  must also be protected from moisture to further prevent corrosion of the reflector  104 .  
         [0020]    Protection from moisture is accomplished by providing a valve assembly  117  disposed on the reflector  104 . The valve assembly  117  is comprised of the vent  105  that allows airflow into the interior of headlamp  100  but prevents moisture from entering into the interior of headlamp  100 . The vent  105  is made of Gore-tex® by W. L. Gore &amp; Associates, Inc., Newark, Del. Gore-tex® is a micro-porous material commonly used for wet weather outer clothing, such as, jackets, boots and the like. The vent  105  also equalizes the pressure in the headlamp  100  with the outside and reduces the internal stresses in the headlamp  100 .  
         [0021]    In a preferred embodiment, a vent  105  is located at the top of the headlamp  100  where the heat of the light source  102  will act to promote the greatest convective flow of hot air. The heat will also act to dry the micro-porous material out very quickly if it is wet. A second vent  119  maybe located toward the bottom of the headlamp  100  that will allow the vents  105 ,  119  to let air into and out of the headlamp  100 . As previously stated, the vents  105 ,  119  will prevent moisture from entering the interior of headlamp  100  and provide pressure equalization between outside of headlamp  100  and the inside of headlamp  100 . As the headlamp  100  heats up with the light source  102  energized, the air within the headlamp  100  expands and creates pressure. Because the light source  102  gets very hot, the pressure inside the headlamp  100  may be significant. The vents  105 ,  119  allow the pressure within the headlamp  100  to be relieved to the outside and eventually the pressure is equalized and so stress is relieved. This headlamp  100  is structured to be an exact replacement for the 7″ round sealed beam headlamp except with a replaceable light source  102  and uses the exact same hardware for installation.  
         [0022]    The foregoing detailed description is merely illustrative of several physical embodiments of the invention. Physical variations of the invention, not fully described in the specification, may be encompassed within the purview of the claims. Accordingly, any narrower description of the elements in the specification should be used for general guidance, rather than to unduly restrict any broader descriptions of the elements in the following claims.