Patent Publication Number: US-6981793-B2

Title: Headlamp bulb

Description:
The invention relates to a headlight lamp in accordance with the preamble of patent claim  1 . 
   I. PRIOR ART 
   Such a headlight lamp is disclosed, for example, in German Laid-open Patent Application DE 199 51 203 A1. This patent application describes a headlight lamp having a lamp vessel, an incandescent filament arranged therein, a lamp base in which the lamp vessel is anchored, and two contact lugs which extend in the longitudinal direction of the lamp and serve to contact the supply leads, projecting from the lamp vessel, for the incandescent filament. The lamp base further has a flange with three lugs which are of resilient design and for their part cooperate with three reference noses in order to fix the lamp in a headlight in the manner of a bayonet lock. The electric connection of the headlight lamp to the power supply unit is performed independently of the abovenamed bayonet lock with the aid of a plug which is pushed onto the contact lugs after the lamp is mounted in the headlight. 
   II. SUMMARY OF THE INVENTION 
   It is the object of the invention to provide a headlight lamp with improved electric terminals. 
   This object is achieved according to the invention by means of the features of patent claim  1 . Particularly advantageous designs of the invention are described in the dependent claims. 
   The headlight lamp according to the invention has at least one lamp vessel, in which at least one luminous means is enclosed, at least two supply leads, projecting from the at least one lamp vessel, for supplying power to the at least one luminous means, a lamp base which has a metallic base part, in which the at least one lamp vessel is anchored, and which has the means for forming a bayonet lock with a headlight, and at least two electric terminals, which are designed as contact lugs and are connected to the supply leads, the lamp base having a plastic ring which is connected to the metallic base part and in which the at least two contact lugs are embedded, and the contact lugs being arranged in a common plane perpendicular to the ring axis, and projecting in each case in the radial direction from the plastic ring. 
   The above described, inventive configuration of the lamp base, and the arrangement of the contact lugs render it possible also to make electric contact with the lamp in the headlight simultaneously with the locking of the bayonet lock between the lamp and the headlight. In order to lock the bayonet lock, the lamp is rotated about its longitudinal axis by approximately a quarter turn, as a result of which the contact lugs projecting radially beyond the plastic ring are also brought simultaneously into contact with the electric holder contacts of the headlight. There is thus no need for any additional plugs in order to connect the contact lugs of the lamp to the electric power supply unit. Moreover, according to the invention the contact lugs of the lamp are arranged in a common plane and embedded in a plastic ring which serves to hold the contact lugs and insulate them electrically. The mounting of the headlight lamp according to the invention is thereby substantially simplified. Owing to the arrangement in the common plane, the contact lugs can be produced from a unipartite stamped sheet-metal part which is embedded in the plastic ring, in order to separate the connecting webs between the contact lugs subsequently in the case of the stamped sheet-metal part fixed in the plastic ring. The plastic ring is advantageously designed as an injection-molded part, in order to implement the embedding of the contact lugs in the contact ring in the simplest possible way. Moreover, the end, averted from the lamp vessel, of the lamp base of the headlight lamp according to the invention is advantageously fitted with a web running along a diameter of the plastic ring. This web is suitable as a grip for inserting the lamp into the headlight, and thereby facilitates the changing of the lamp. 

   
     III. DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENTS 
     The invention is explained in more detail below with the aid of a preferred exemplary embodiment. In the drawing: 
       FIG. 1  shows a side view of the first exemplary embodiment of the headlight lamp according to the invention, 
       FIG. 2  shows a plan view of the headlight lamp illustrated in  FIG. 1   
       FIG. 3  shows a plan view of the plastic ring with the contact lugs embedded therein, and 
       FIG. 4  shows a side view of the second exemplary embodiment of the headlight lamp according to the invention. 
   

   The preferred exemplary embodiment, illustrated in  FIG. 1 , of the invention is a two-filament halogen incandescent lamp which is provided for insertion into a motor vehicle headlight. This lamp has a vitreous, essentially cylindrical lamp vessel  1 , inside which there are enclosed two incandescent filaments  2 ,  3  of which one is arranged axially and the other in a transverse fashion to the longitudinal axis A of the lamp or the cylinder axis of the lamp vessel  1 . The axially arranged incandescent filament  2  is surrounded in part by an anti-dazzle device  4 , likewise arranged inside the lamp vessel  1 . Three supply leads  5 ,  6  and  7 , which are led out of the end of the lamp vessel  1  near the base, serve to hold and supply power to the incandescent filaments  2 ,  3  and the anti-dazzle device  4 . The end of the lamp vessel  1  near the base is anchored with a clamping fit in a cutout in a metallic holder  8  which is, for its part, a component of the lamp base  9 . The metallic holder  8  is fixed in a metallic adjusting ring  10 , which is welded to the reference ring  11 . The reference ring  11  has three reference noses  11   a ,  11   b ,  11   c  which extend radially outwards in a fashion substantially perpendicular to the longitudinal axis A and lie in a common plane. These reference noses  11   a – 11   c  are arranged along the circumference of the reference ring  11  at a spacing of 120 degrees. The reference nose  11   a  is wider than the two other reference noses  11   b ,  11   c  in design, in order to define an orientation or installation position of the lamp in the headlight. By means of the conventional adjusting processes, during welding of the metal base parts  8 ,  10  and  11  the two incandescent filaments  2 ,  3  are aligned exactly with reference to the three reference nose  11   a – 11   c  and the reference plane defined by them, such that the orientation and installation position of the three reference noses  11   a – 11   c  inside the headlight reflector can also uniquely fix the arrangement of the incandescent filaments  2 ,  3  in the reflector during insertion of the lamp into a headlight. The reference ring  11  is welded to the metallic, annular base flange  12 , whose flange plane is arranged substantially perpendicular to the longitudinal axis A. The base flange  12  has three resiliently designed lugs  12   a ,  12   b ,  12   c  which are arranged uniformly along its annular circumference and develop a spring action in the longitudinal direction A of the lamp. The reference noses  11   a – 11   c  serve as opposing bearings to the resilient lugs. The reference noses  11   a – 11   c  form a bayonet lock together with the base flange  12  and its lugs  12   a – 12   c , as well as with the opening, correspondingly configured as lamp holder, of the headlight reflector. After the locking of the bayonet lock, the rim of the abovenamed opening of the headlight reflector is arranged with a clamping fit between the reference noses  11   a – 11   c  and the lugs  12   a – 12   c . Serving to provide lateral support for the lamp at the rim of the headlight reflector opening is a press-on spring  16  which projects outward through a cutout in the annular collar  12   d  of the base flange  12 . 
   Adjoining the base flange  12  is the plastic ring  13 , which is designed as an injection-molded part and from which project three metallic contact lugs  13   a ,  13   b ,  13   c , which are connected in each case in an electrically conducting fashion to a supply lead  5 ,  6 ,  7  and form the electric contacts of the headlight lamp. For this purpose, the ends, arranged inside the plastic ring  13 , of the contact lugs  13   a – 13   c  are provided in each case with a cutout  15   a ,  15 ,  15   c  for holding in each case one of the supply leads  5 ,  6 ,  7 . The ends of the supply leads  5 ,  6 ,  7  are welded into the cutouts  15   a – 15   c , in each case with one of the contact lugs  13   a – 13   c . The three contact lugs  13   a – 13   c  and, in particular, also their contact surfaces are arranged in a common plane in a fashion perpendicular to the axis of the plastic ring  13 , and thus also substantially perpendicular to the longitudinal axis A. They  13   a – 13   c , extend in the radial direction and project radially from the plastic ring  13 . The three contact lugs  13   a – 13   c  are arranged along the circumference of the plastic ring  13  at a spacing of in each case 60 degrees. The plastic ring  13  is provided with a radially running groove  16 , serving as positioning aid, in order to fix the position of the contact lugs  13   a – 13   c  with reference to the reference noses  11   a – 11   c  when mounting the base. The middle contact lug  13   b  is arranged diametrically with reference to the wide reference nose  11   a . The contact lugs  13   a – 13   c  are brought into contact with the corresponding electric holder contacts of the headlight by the rotary movement during locking of the bayonet lock. 
   The end, averted from the lamp vessel  1 , of the lamp base  9  is formed by the grip part  14 , which consists of plastic and is fixed by an undetachable plug-in connection on the plastic ring  13  and on the base flange  12 . The grip part  14  has a web  14   a  running perpendicular to the longitudinal axis A along a diameter of the plastic ring  13 . The web  14   a  can serve as a grip for locking and unlocking the bayonet lock when changing the lamp. 
   The invention is not limited to the exemplary embodiment explained in more detail above. It can also be applied, for example, to headlight lamps which have only one incandescent filament or one luminous means and, consequently, only two contact lugs. 
   A headlight lamp of this type having only one incandescent filament and two contact lugs is schematically represented in  FIG. 4 . The same reference numerals are used for identical parts as in  FIG. 1  of the above described exemplary embodiment. The exemplary embodiment illustrated in  FIG. 4  has only two contact lugs  113   a ,  113   b  which are in each case connected to one of the supply leads  5 ,  7 . The contact lugs  113   a ,  113   b  are arranged diametrically with reference to the plastic ring  113 , extend in radial direction and project from the plastic ring  113  in radial direction. Their contact surfaces are aligned perpendicular to the axis of the ring or the longitudinal axis of the lamp. The plastic ring is fitted with an integrally formed weblike grip member  114  that extends along a diameter of the plastic ring  113 .