Abstract:
An incandescent light source finds particular use in a lamp having a reflector as provided. The light source comprises an elongated envelope having a major axis and a filament secured therein such that a major axis of the filament is parallel or offset from the major axis of the envelope. A first fin is secured to the elongated envelope which supports the envelope against vibrations. A base is also connected to the light source. The base includes a body, two leads, a flange extending radially from the body, a projection extending axially from the flange, and a twist lock construction capability comprising lugs that defines a fiducial plane for setting the focal point of the incandescent light source. To connect the base to the envelope, the projection is dimensioned to extend through an aperture of the reflector then rotated to engaging the reflector thereby securing the base to the reflector.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present disclosure relates to an incandescent lamp and more particularly to an incandescent lamp including a self-sealing mounting base. It finds particular application in the automotive industry for use in a fog lamp. However, it is to be appreciated that the present invention is also amenable to other like environments and applications.  
         [0002]     A typical fog lamp assembly includes a light source or lamp located at a focus of a reflector so that light emitted from the light source is directed through a lens of the assembly to achieve a predetermined beam pattern. Generally, the lamp assembly uses a halogen light source.  
         [0003]     The light source is typically fixed onto a base and mounted to the lamp assembly. The base and the light source mounted thereon form a replaceable bulb. In order for the lamp to be acceptable to the average consumer, it must be cost competitive relative to other similar lamp assemblies and must also be reliable. Therefore the replacement bulb must be of a construction with few parts for ease of assembly, quality and cost reasons. Proper alignment and stability of the light source inside the lamp assembly are important requirements for the performance of the lamp. The light source must be aligned in a specific position with respect to the base. Once aligned and precisely locked in the appropriate position with respect to the base, the bulb must remain in that aligned position during use for acceptable performance of the lamp assembly.  
         [0004]     There is a need for increased stability in association with a replacement lamp, as well as providing a twist and lock arrangement that eliminates the need for a retaining ring, in combination with assured optical capabilities. Heretofore, known arrangement have addressed one or the other of these problems. A need exists to provide a replaceable lamp that has superior optical capabilities, OEM quality, and can be economically sealed to a reflector housing.  
         [0005]     Generally, a gimbal device is one of the mechanisms used to align the light source with respect to the plastic base. The gimbal, which serves as a holder for the lamp may also be required to insulate the plastic base from the heated bulb. The gimbal is generally contained within a cylindrical opening in the plastic base from which the light source can be aligned, after which the gimbal is attached to the plastic base by either thermal or mechanical means so as to secure the lamp in the aligned position.  
         [0006]     While some prior art replaceable lamp designs and constructions are satisfactory, it is desirable to develop continued improvements and alternative designs for replaceable lamps. For example, it would be desirable to simplify assembly and provide a base for reliability in firmly supporting and aligning the light source, without the need for a gimbal. A replaceable lamp without a gimbal enables the possibility to design the lamp with a shorter light-center-length (LCL) and shorter overall length. This enables a fog lamp reflector with shorter focal length. Short focal length fog lamps are preferred for economical reasons as they require less material to fabricate. Shorter focal length fog lamps also meet the need from vehicle manufacturers to have reduced build-in depth of lighting fixtures at the front end of the vehicle because of the increasing underhood packaging density with emergence of new technologies and safety requirements. Moreover, there is a need to achieve alignment with minimal effort and manipulation by the customer.  
         [0007]     Accordingly, the present invention provides a new and improved incandescent lamp including a self sealing mounting base design which overcomes difficulties with the prior art while providing more advantageous overall results.  
       BRIEF DESCRIPTION OF THE INVENTION  
       [0008]     An incandescent light source finds particular use in a lamp having a reflector is provided. The light source comprises an elongated envelope having a major axis and a filament secured therein such that a major axis of the filament is parallel or offset from the major axis of the envelope. A first fin is secured to the elongated envelope, which supports the envelope against vibrations. Other means of support for the light source of course could be used without departing from the scope of and intent of the subject invention. A base is also connected to the light source. The base includes a body, a flange extending radially from the body, a projection extending axially from the flange, and a twist lock construction capability that incorporates a reference plane perpendicular to the light source filament. To connect the base to the reflector, the projection is dimensioned to extend through an aperture of the reflector and the base is rotated to allow the twist lock to engaging the reflector thereby securing the replaceable bulb to the reflector.  
         [0009]     An incandescent light source preferably comprises an envelope having a major axis and an elongated filament received in the envelope such that a major axis thereof is generally aligned with the major axis of the envelope. First and second rigid fins are electrically connected to and extend generally normal from the envelope for supporting the envelope against vibrations. Other means of support for the light source of course could be used without departing from the scope of and intent of the subject invention. A base is electrically connected and secured to the light source. A gasket is attached to the base for sealing the base to a reflector. The gasket has a sealing surface extending in a plane transverse to the major axes and is held in place by the radial flange on the base.  
         [0010]     The light source includes an envelope formed from a light transmissive material and has a major axis. An axially extending filament is received in the envelope, a major axis of the filament being offset from the major axis of the envelope. A fin is secured to and extends generally normal from the envelope for supporting the envelope against vibrations. Other means of support for the light source of course could be used without departing from the scope of and intent of the subject invention. The fin electrically interconnects with the filament. A base is secured to the light source, the base including means for sealingly mounting the base to a reflector.  
         [0011]     Still other aspects of the invention will become apparent from a reading and understanding of the detailed description of the several embodiments herein below. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is an elevational view, in partial cross-section, of a portion of an incandescent light source of the present invention. Other means of support for the light source of course could be used without departing from the scope of and intent of the subject invention.  
         [0013]      FIG. 2  is a side elevational view, in partial cross-section, of the incandescent light source of  FIG. 1 .  
         [0014]      FIG. 3  is a side elevational view of a base according to a first embodiment of the incandescent light source of  FIG. 1 . Other shapes or types of base could be used without departing from the scope of and intent of the subject invention.  
         [0015]      FIG. 4  is a bottom plan view of the base of  FIG. 3 .  
         [0016]      FIG. 5  is a cross-sectional view of the base taken generally along line A-A of  FIG. 4 .  
         [0017]      FIG. 6  is a cross-sectional view of the base taken generally along line B-B of  FIG. 4 .  
         [0018]      FIG. 7  is a top plan view of the base of  FIG. 3 . Base twist lock is for reference only and would be design specific for this application.  
         [0019]      FIG. 8  is a side elevational view of the base of  FIG. 7 .  
         [0020]      FIG. 9  is a side elevational view of the base of  FIG. 7 .  
         [0021]      FIG. 10  is a side elevational view of the base of  FIG. 7 .  
         [0022]      FIG. 11  is a cross-sectional view of the base taken generally along line C-C of  FIG. 7 .  
         [0023]      FIG. 12  is a front elevational view of a base according to a second embodiment of the incandescent light source of  FIG. 1 .  
         [0024]      FIG. 13  is a side elevational view of the base of  FIG. 12 .  
         [0025]      FIG. 14  is a top plan view of the base of  FIG. 12 .  
         [0026]      FIG. 15  is a side elevational view of the base of  FIG. 12 .  
         [0027]      FIG. 16  is a side elevational view of the base of  FIG. 12 .  
         [0028]      FIG. 17  is a cross-sectional view of the base taken generally along line A-A of  FIG. 12 .  
         [0029]      FIG. 18  is a cross-sectional view of the base taken generally along line B-B of  FIG. 14 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]     With reference to  FIGS. 1 and 2 , an incandescent light source  10  finding particular use in a fog lamp assembly (not shown) having a reflector (not shown) is illustrated. The incandescent light source has wattage between approximately twenty (20) watts and approximately sixty (60) watts. When used in the fog lamp assembly, the reflector receives light from the light source  10  and directs it through a lens to provide a predetermined beam pattern. The light source comprises an elongated pressurized envelope  12  formed from a vitreous or light transmissive material. In a preferred arrangement, the elongated envelope is formed of a quartz material. Of course, other light transmissive materials can be used without departing from the scope and intent of the subject invention.  
         [0031]     The elongated envelope  12  includes a first portion  14  forming a sealed cavity and a second portion  16  or press seal base extending therefrom. The first portion  14  is generally cylindrical in cross-section and has a major axis  20 . The second portion  16  is generally rectangular in cross-section; although, it should be appreciated that the second portion can have other conformations configured for receipt in a base to be described further below. An end  22  of the first portion  14  can be coated with a non-transmissive material to prevent stray light or glare as is well known in the art.  
         [0032]     Contained within the elongated envelope  12  is a filament  30 , usually of tungsten. The filament is secured for general alignment with the major axis  20  of the envelope. Specifically, the filament  30  extends axially within the envelope such that a major axis  32  of the filament is generally parallel or offset from the major axis of the envelope  12 . Opposing ends of the filament  30  are mechanically secured and electrically connected to first and second lead inner wires  34   a ,  36   a , respectively. The inner lead wires are preferably connected to thin metal foils (not shown), such as molybdenum foils, located in the second portion  16  of the envelope  12 . More particularly, the molybdenum foils are mechanically and electrically connected to outer lead wires  34   b ,  36   b  that extend outwardly from the press seal base  16  of the lamp envelope.  
         [0033]     When energized, the filament  30  emits radiation.  
         [0034]     With continued reference to  FIGS. 1 and 2 , first and second fins  40 ,  42 , respectively, are secured to the elongated envelope  12  to support the envelope against vibrations. Other means of support for the light source of course could be used without departing from the scope of and intent of the subject invention. The first and second fins are generally thin, planar components (compare  FIGS. 1 and 2 ) and extend generally normal from opposing sides of the second portion  16  of the envelope. Each fin  40 ,  42  includes a first section  44 ,  46 , respectively, mounted to the second portion  16  and a second section  48 ,  50 , respectively, extending generally perpendicular therefrom. Each first section  44 ,  46  is generally “C” shaped to define a channel (not shown) dimensioned to receive an end of the second portion  16 . Each second section  48 ,  50  is generally “L” shaped, as seen in  FIG. 1 , and a portion  52 ,  54  of each respective second section extends beneath the second portion  16  and is mechanically and electrically connected to the first and second lead wires  34 ,  36 .  
         [0035]     The first and second lead wires  34 ,  36  and the first and second fins  40 ,  42  are mechanically and electrically connected to respective first and second spaced apart leads  60 ,  62  ( FIG. 3 ), in a well known manner. The leads are formed from an electrically conductive material to provide electrical current to the filament  30 .  
         [0036]     As shown in  FIGS. 3 , the leads  60 ,  62  extend through a base  70  and provide mechanical support to the light source  10 . In this manner, the light source is fixed relative to the base  70 , and an electrical connection can be easily established through the base with the leads  60 ,  62  which, in turn, provide current to the filament  30  through the first and second lead wires  34 ,  36  and the first and second fins  40 ,  42 . Additionally, because the leads are slightly offset from a center axis of the base  70 , the leads also provide a desired mounting orientation of light source  10 .  
         [0037]     With reference to  FIGS. 3-6 , the base  70 , according to one embodiment of the present invention, includes a body  72  having a flange  74  extending radially therefrom. As shown in  FIGS. 4 and 5 , the body  72  is generally round and includes a wall  80  defining a cavity  82 . A shelf  86  extends radially from an inner surface of wall  80  of the body. As shown in  FIG. 6 , electrically connected to the leads  60 ,  62  are a pair of electrical blades or contacts  90 ,  92  separated by a divider  94  extending axially from an end wall  96  of the body and radially spaced from the wall  80 . The blades  90 ,  92  are mounted and supported in a pair of spaced apart frusto-pyramidal projections  100 ,  102  extending outwardly from the end wall  96 . The blades are adapted to be electrically connected to a receptacle or an electrical source (not shown) in a manner well known in the art. Other shapes of bases used to mount the light source of course could be used without departing from the scope of and intent of the subject invention.  
         [0038]     With reference again to  FIG. 3 , and with additional reference to  FIG. 7 , the base  70  further includes a hollow projection  110  extending axially from the flange  74 . As shown in  FIGS. 8-10 , at least one lug extends radially outwardly from a surface of the projection adjacent an end portion of the projection. In this embodiment, the base  70  includes three circumferentially spaced lugs  112 ,  114 , and  116  ( FIG. 7 ), respectively. The base  70  also includes an annular gasket  118  (shown in dashed lines in  FIG. 3 ) attached to the projection  110  and disposed between the flange  74  and the lugs for sealingly mounting the base to the reflector. The gasket has a sealing surface extending in a plane generally transverse to the major axis  20 . Bottom surfaces  120 ,  122 ,  124  of each respective lug  112 ,  114 , and  116  define a reference or fiducial plane for setting the focal point of the incandescent light source  10 .  
         [0039]     To assemble the incandescent light source  10 , the first and second spaced apart leads  60 ,  62  are secured to the first and second fins  40 ,  42  in a well-known manner. Once secured, the major axis  32  of the filament  30  is coincident with a center axis of the projection  110 . As such, the center axis of the projection is offset from the major axis  20  of the envelope  12 .  
         [0040]     To connect the base  70  to the reflector, the projection  110  including the lugs are advanced through a mounting aperture of the reflector such that the bottom surfaces of the lugs are adjacent an inner surface of the reflector. The aperture is dimensioned to allow the base projection to be inserted and rotated to lock into position so that the light source  10  is located at the focus of the reflector. For ease of insertion of the lugs  112 ,  114 ,  116  through the reflector aperture, each lug includes a chamfered surface  130 ,  132 ,  134 . The base  70  is then rotated or twisted to sealingly secure the base to the reflector. Particularly, as the base is twisted, ramps  138 ,  140 ,  142  extending from the lugs engage the inner surface of the reflector. This, in turn, further advances the projection  110  relative to the reflector that presses the gasket  118  against an outer surface of the reflector thereby sealing the base to the reflector. The base is rotated until a stop  146  ( FIGS. 8 and 11 ) extending from bottom surface  124  of lug  116  engages an edge of the reflector aperture and a lock  148 , also located on bottom surface  124 , extends through the reflector aperture.  
         [0041]     Similar to the aforementioned embodiment of the base  70 , an additional embodiment of a base  200  is shown in  FIGS. 12-18 . Since most of the structure and function is substantially identical, reference numerals with a single primed suffix (′) refer to like components (e.g., projection  110  is referred to by reference numeral  110 ′), and new numerals identify new components in the additional embodiment. The primary distinctions relate to a body  202  of the base  200  which is generally normal to the projection  110 ′.  
         [0042]     As shown in  FIGS. 12-14 , the base  200  includes the generally round body  202  and a flange  204  extending substantially perpendicularly from a first end portion  206  of the body. As shown in  FIGS. 14 and 17 , a second end portion  208  of the body extends outwardly from the body. The body  202  includes an inner wall  210  defining a cavity  212 . A shelf  218  extends radially from the inner wall  210  of the body. As described above relative to the first embodiment, electrically connected to the leads  60 ′,  62 ′ are a pair of electrical blades or contacts  90 ′,  92 ′ separated by a divider  94 ′ extending outwardly from the inner wall  210  and an end wall  220  of the body and from. The blades are mounted and supported in a pair of spaced apart projections  100 ′,  102 ′ extending outwardly from the end wall  96 ′ ( FIGS. 12 and 18 ).  
         [0043]     The present disclosure has been described with reference to several embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the disclosure be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.