Patent Publication Number: US-7911122-B2

Title: Lamp base with a cutout and lamp with corresponding lamp base

Description:
The invention relates to a lamp base as claimed in the preamble of claim  1 . 
     I. PRIOR ART 
     The patent specification EP 1 006 551 B1 has disclosed a lamp base of a vehicle headlamp which is in the form of a metal/plastic base and which has electrical terminals in the form of metal webs. In order to weld the power supply wires, which protrude out of the lamp vessel and are used for supplying power to the incandescent filament, to the metal webs, at least one aperture is provided in the lamp base, through which aperture the weld point is accessible for a laser or another suitable welding tool. In addition, the metal webs are equipped with thread-in means in order to be able to join the bent-back ends of the power supply wires to the metal webs. 
     II. DESCRIPTION OF THE INVENTION 
     The object of the invention is to provide a lamp base of the generic type in which the ends of power supply wires and electrical terminals which are to be connected to one another have improved accessibility during the connection process. 
     This object is achieved according to the invention by the features of claim  1 . Particularly advantageous embodiments of the invention are described in the dependent claims. 
     The lamp base according to the invention has a lamp base with a plastic base part, which is provided with electrical terminals for supplying power to at least one luminous means of the lamp which is surrounded by a lamp vessel, the electrical terminals being in the form of metal webs, whose first end protrudes laterally, perpendicular to the longitudinal extent of the lamp base, out of the plastic base part in each case for the purpose of producing the electrical contact with a lampholder, and whose second end is provided in each case for connection to a power supply wire, which is passed out of the lamp vessel, for the at least one luminous means, the plastic base part having, on a lower side, which faces away from the lamp vessel, of the plastic base part, a cutout, in which the second ends of the metal webs are arranged. As a result, the apertures provided in the lamp base in accordance with the prior art for laser welding purposes are no longer required. The connection between the second ends of the metal webs and the power supply wires for the at least one luminous means can be carried out from the lower side of the plastic base part since the second ends of the metal webs are accessible in the cutout on the lower side of the plastic base part. 
     Advantageously, the plastic base part has funnel-like leadthroughs, which extend as far as its lower side, for the power supply lines of the at least one luminous means in order to make it easier to thread in or lead the abovementioned power supply wires through the plastic base part. 
     The second ends of the metal webs are advantageously each provided with an aperture or a notch for accommodating a power supply wire in order to simplify the connection to the power supply wire. As a result, the power supply wire can be connected to the corresponding metal web on the lower side, which faces away from the plastic base part, of the second end of the respective metal web. 
     In accordance with the preferred exemplary embodiment of the invention, the second ends of the metal webs are arranged in a common plane perpendicular to the longitudinal extent of the lamp base in order to obtain a compact design of the lamp base with as low an installation height as possible. 
     Preferably, the lamp base has a closure element, which is used for covering the cutout on the lower side of the plastic base part. As a result, the connections between the power supply wires and the metal webs are protected against damage and contamination. 
     The closure element is preferably fixed on the plastic base part by means of a clamping fit in order to ensure a connection between the closure element and the plastic base part which can be produced easily. 
     In addition, the closure element is preferably in the form of a coding for the lamp, with the result that the user of the lamp can use the closure element to identify which version of the lamp type he has in front of him. In particular, the coding can be implemented by the shape or color of the closure element. For example, lamps of the same type which, however, belong to different interchangeable versions can have differently constructed or colored closure elements in order to be able to distinguish between them more easily. For example, vehicle headlamps which generate light of different color temperatures, such as, for example, the lamp versions going under the trade names OSRAM COOL BLUE and OSRAM LIGHT@DAY, can thereby be distinguished from one another more easily. 
     In accordance with a preferred exemplary embodiment of the invention, the cutout for the second ends of the metal webs is arranged on the lower side, which is remote from the lamp vessel, of a disk-shaped section of the plastic base part, and the first ends of the metal webs protrude laterally, perpendicular to the longitudinal extent of the lamp base, out of at least one web of the plastic base part, which is integrally formed on the lower side of the disk-shaped section and runs in the direction of the longitudinal extent of the lamp base. Thus, the plastic base part can be in the form of an injection-molded part, in which the metal webs are embedded in such a way that their first ends protrude laterally out of the lamp base and their second ends are accessible via a cutout on the lower side in order to be able to connect them to the power supply wires. 
     Preferably, the at least one web of the plastic base part is provided with guide means for the closure element, and the closure element is shaped in such a way that it forms, with the at least one web, a grip for inserting the lamp into a lampholder. In particular, the closure element can be shaped in such a way that it enlarges the width of the abovementioned web and thus a grip is formed which makes it easier to insert or screw the lamp into a lampholder. 
     The lamp base according to the invention is advantageously suitable for a vehicle headlamp. 
    
    
     
       III. DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENT 
       The invention will be explained in more detail below with reference to a preferred exemplary embodiment. In the drawing: 
         FIG. 1  shows a side view of a vehicle headlamp which is equipped with the lamp base in accordance with the preferred exemplary embodiment of the invention, 
         FIG. 2  shows a side view of the individual components of the lamp base of the lamp depicted in  FIG. 1 , 
         FIG. 3  shows a plan view of the lower side, which faces away from the lamp vessel, of the lamp base or of the vehicle headlamp depicted in  FIG. 1 , 
         FIG. 4  shows an illustration of the physical arrangement and design of the contact lugs of the vehicle headlamp depicted in  FIG. 1 , and 
         FIG. 5  shows a plan view of one of the reference tabs of the lamp base depicted in  FIG. 1  or  2 . 
     
    
    
       FIG. 1  illustrates a halogen incandescent lamp for a vehicle headlamp which has been provided with the lamp base according to the invention. This halogen incandescent lamp has a vitreous substantially cylindrical lamp vessel  10 , in whose interior are arranged two incandescent filaments  21 ,  22 , which are aligned parallel to the lamp vessel axis and are used, for example, for producing an upper beam and a daytime running light or an upper beam and a lower beam. The incandescent filaments  21 ,  22  are, for example, in the form of single-coil or double-coil tungsten wires. The outgoing filament ends  211 ,  212  and  221 ,  222  of the incandescent filaments  21  and  22 , respectively, each have a molybdenum foil wound around them which is used as a welding aid when welding the outgoing filament ends  211 ,  212  and  221 ,  222  to the power supply lines for the incandescent filaments  21 ,  22 . A sealed end  11  of the lamp vessel  10  is anchored in a lamp base  30 . The lamp vessel dome which faces away from the lamp base  30  is provided with an opaque coating  12 . The first incandescent filament  21  is partially surrounded by an anti-dazzle device  4  shaped out of sheet molybdenum. The anti-dazzle device  4  is borne by a first power supply wire  51 , which, together with a second power supply wire  52  and a third power supply wire  53 , is used for supplying power to the two incandescent filaments  21 ,  22 . For this purpose, a first outgoing filament  211  of the first incandescent filament  21  is welded by means of projection welding to a welding lug  41  of the anti-dazzle device  4  and as a result is electrically conductively connected to the first power supply wire  51  via the anti-dazzle device  4 . The second outgoing filament end  212  of the first incandescent filament  21  is welded to the third power supply wire  53 . The first outgoing filament end  221  of the second incandescent filament  22  is likewise welded to the third power supply wire  53 . The second outgoing filament end  222  of the second incandescent filament  22  is welded to the second power supply wire  52 . The three power supply wires  51 ,  52 ,  53  each consist of molybdenum and are fixed between two quartz glass webs  13  which are fused with one another, with the result that they are arranged in a common plane. The three power supply wires  51 ,  52 ,  53  are passed through the sealed end  11  of the lamp vessel  10  and in each case electrically conductively connected to one of the three metal webs  61 ,  62  or  63  in the form of contact lugs. The three contact lugs  61 ,  62 ,  63  protrude laterally out of the lamp base  30  and form the electrical terminals of the halogen incandescent lamp. 
     The lamp base  30  has a plastic base part  31  in the form of an injection molded part, in which the contact lugs  61 ,  62 ,  63  are embedded. The plastic base part  31  has a section  311  in the form of a circular disk and two mutually opposite webs  312 ,  313 , which are integrally formed on the lower side, which is remote from the lamp vessel  10 , of the section  311  and extend parallel to the axis of the section  311  in the form of a circular disk. The three contact lugs  61 ,  62 ,  63  each consist of sheet metal and are embedded in the first web  312 , with the result that their free ends  611 ,  621 ,  631  protrude laterally or radially out of the web  312  of the plastic base part  31  and are arranged one above the other in the direction of the lamp longitudinal axis. The ends  612 ,  622 ,  632 , which are welded to the power supply wires  51 ,  52 ,  53 , of the contact lugs  61 ,  62 ,  63  are arranged close to the axis of the section  311  in the form of a circular disk, in a cutout  3110  on its lower side, i.e. on that side of the section  311  in the form of a circular disk which is remote from the lamp vessel. Details relating to the contact lugs  61 ,  62 ,  63 , in particular their design and their physical arrangement, are illustrated schematically in  FIG. 4 . The ends  612 ,  622 ,  632 , which are to be welded to the power supply wires  51 ,  52 ,  53  of the contact lugs  61 ,  62 ,  63  each have an aperture  6120 ,  6220 ,  6320 , through which the corresponding power supply wire  51 ,  52  or  53  is passed and, on the lower side, which is remote from the lamp vessel  10 , of the contact lugs  61 ,  62  or  63 , is welded to the end  612 ,  622  or  632  of this contact lug  61 ,  62 ,  63 . In order that the power supply wires  51 ,  52 ,  53  can be threaded without any problems into the aperture  6120 ,  6220 ,  6320  of the corresponding contact lug end  612 ,  622 ,  632 , the disk-shaped section  311  of the plastic base part  31  has funnel-like leadthroughs for the power supply wires  51 ,  52 ,  53 , which extend from the upper side, which faces the lamp vessel  10 , of the section  311  in the form of a circular disk as far as its lower side and are tapered conically in the direction of the lower side and are positioned above the apertures  6120 ,  6220 ,  6320 . A closure element  32 , which likewise consists of plastic and is inserted into the interspace between the two webs  312 ,  313 , and is connected via guiderails  3120 ,  3130  to the webs  312 ,  313 , closes the abovementioned cutout  3110  on the lower side of the section  311  in the form of a circular disk. The pin  321  in this case engages in an appropriately shaped receptacle  3111  on the lower side of the section  311  in the form of a circular disk and brings about fixing of the closure element  32  on the plastic base part  31  with a clamping fit. 
     The closure element  32  fills the interspace between mutually opposite webs  312 ,  313  and with these webs forms a grip for inserting the lamp into a corresponding installation opening of a vehicle headlamp. In order to provide coding for different mutually compatible versions of the same type of vehicle headlamps which can be interchanged in the vehicle headlamp, the closure element  32  preferably consists of a colored plastic, the closure elements  32  for different lamp versions being manufactured from different colored plastics. 
     A metallic spring ring  33 , which is interlocked in the plastic material of the section  311  by means of a plurality of integrally formed claw pairs  331 , is arranged on the upper side, which faces the lamp vessel  10 , of the section  311  in the form of a circular disk of the plastic base part  31 . For this purpose, for example, the upper side of the section  311  is provided with an annular depression, whose side wall has webs, which are each arranged between the claws of a claw pair  311 . The spring ring  33  is in the form of an annular disk with a surface running perpendicular to its ring axis. The ring axis of the spring ring  33  is arranged coaxially with respect to the ring axis of the section  311 . The outer diameter of the spring ring  33  substantially corresponds to the outer diameter of the section  311  on its upper side. The spring ring  33  has three equidistantly arranged, integrally formed spring tabs  332 ,  333 ,  334 , which protrude out of the surface or ring plane of the spring ring  33 , which is in the form of an annular disk, and exert a spring effect in the direction of the ring axis. 
     The lamp base  30  in addition has a first metal sleeve  34 , which is in the form of a metallic hollow cylinder  34  which is open at its ends and is anchored by means of radiofrequency-induced heating in the plastic material on the upper side of the section  311  in the form of a circular disk of the plastic base part  31 . The first metal sleeve  34  is arranged coaxially with respect to the section  311  and the spring ring  33 , its outer diameter being smaller than the inner diameter of the spring ring  33 . A contact-pressure spring  341 , which is in the form of a leaf spring, is fixed on the casing surface of the first metal sleeve  34  on its inner side, protrudes outward through an aperture in the casing surface and exerts a spring effect in the direction of a diameter of the first metal sleeve  34 . The casing surface of the first metal sleeve  34  has a plurality of holes  342 , into which the softened plastic material of plastic base part  31  enters when the metal sleeve  34  is heated during fusing to the plastic base part  31 , with the result that the metal sleeve  34 , once the plastic melt has solidified, is anchored in the plastic base part  31 . 
     The lamp base  30  also has a second metal sleeve  35 , which is in the form of a metallic hollow cylinder  35  which is open at its ends and which is arranged coaxially with respect to the first metal sleeve  34  and is welded to it. An annular collar  350  with three reference tabs  351 ,  352 ,  353  is integrally formed on the lower edge, which faces the first metal sleeve  34 , of the second metal sleeve  35 . The reference tabs  351 ,  352 ,  353  protrude from the casing surface of the second metal sleeve  35  and extend in each case in the direction of a diameter of the second metal sleeve  35 . The reference tabs  351 ,  352 ,  353  are arranged equidistantly along the circumference of the annular collar  350 . Details of the reference tabs  351 ,  352 ,  353  are illustrated in  FIG. 5  using the example of the reference tab  351 . The reference tab  351  has, on its lower side facing away from the lamp vessel  10 , a centrally arranged, radially running rib  3510 . On both sides of the rib  3510 , the reference tab  351  has downwardly curved surface sections  3511 ,  3512 , which are each delimited by the rib  3510  and one of the radially running outer edges. The reference tab  352  has a greater width than the two other reference tabs  351 ,  353  in order to be able to define an unambiguous installed position of the lamp. The second metal sleeve  35  has an annular section  354  with a reduced inner and outer diameter on its upper edge facing the lamp vessel  10 . The second metal sleeve  35 , with the annular collar  350  and the three reference tabs  351 ,  352 ,  353  is in the form of a deep-drawn part. 
     The lamp base  30  also includes a fixing ring  36  for holding the sealed end  11  of the lamp vessel  10 . The fixing ring  36  is in the form of a hollow cylinder, whose outer diameter is smaller than the inner diameter of the annular section  354  of the second metal sleeve  35 . That end of the hollow-cylindrical fixing ring  36  which faces the second metal sleeve  35  is designed to be open. The other end of the hollow-cylindrical fixing ring  36  which faces the lamp vessel  10  is covered by a cover face in the form of a circular disk. An aperture, in which the sealed end  11  of the lamp vessel  10  is anchored with a clamping fit, is located in the cover face. For this purpose, a plurality of spring tabs are arranged along the rim of the above-mentioned aperture, which spring tabs are latched in behind glass webs on the sealed end  11  of the lamp vessel  10  and between which spring tabs the sealed end  11  is fixed with a clamping fit. Such a fixing ring  36  and the anchoring of the sealed end  11  is disclosed, for example, in the patent specification EP 0 775 366 B1. The fixing ring  36  is welded to the lamp vessel  10  anchored therein with the second metal sleeve  35  by means of a laser at a plurality of points. In order to align the incandescent filaments  21 ,  22  with respect to the three reference tabs  351 ,  352 ,  353 , the fixing ring  36  including the lamp vessel  10  fixed therein and the incandescent filaments  21 ,  22  enclosed in the lamp vessel  10  is inserted into the second metal sleeve  35  and displaced in the direction of the cylinder axis of the second metal sleeve  35  and inclined with respect to the abovementioned cylinder axis through a specific angle and rotated until the incandescent filaments  21 ,  22  have reached the desired position and orientation. Then, the abovementioned laser welding of the fixing ring  36  and the second metal sleeve  35  in the adjusted position is carried out. 
     In order to fit the halogen incandescent lamp in a vehicle headlamp, the lamp is inserted into the installation opening of the headlamp reflector and, as a type of bayonet closure, is locked in the installation opening by quarter rotation about the longitudinal axis of the lamp. The reference tabs  351 ,  352 ,  353  and the spring tabs  332 ,  333 ,  334  are used for this purpose. The rim of the installation opening of the reflector after the quarter rotation is arranged with a clamping fit between the reference tabs  351 ,  352 ,  353  and the spring tabs  332 ,  333 ,  334 , with the result that the lamp is fixed in the axial direction. The ribs  3510  of the reference tabs  351 ,  352 ,  353  are in this case fitted so as to latch in behind on corresponding webs on the inner side of the reflector in the rim region of the installation opening. The contact lugs  61 ,  62 ,  63 , by means of the quarter rotation when the bayonet closure is locked, are rotated into the position which is required in order to produce an electrical contact with the corresponding lampholder contacts of the headlamp. The leaf spring  341  bears in clamping fashion against the rim of the installation opening and fixes the lamp laterally, i.e. perpendicular to the lamp&#39;s longitudinal axis. The position of the reference tabs  351 ,  352 ,  353  also fixes the position and alignment of the incandescent filaments  21 ,  22  in the reflector of the vehicle headlamp since appropriate cutouts for the reference tabs  351 ,  352 ,  353  are provided in the installation opening of the reflector, and these cutouts only permit a single installation position. 
     The invention is not restricted to the exemplary embodiment described in more detail above. In particular, the cutout  3110 , which is arranged on a lower side, which faces away from the lamp vessel  10 , of the plastic base part  31 , can also be formed, for example, only by the lower side of the section  311  in the form of a circular disk and the webs  312 ,  313  of the plastic base part  31  and does not need to comprise a depression in the lower side of the section  311  in the form of a circular disk of the plastic base part  31 .