Abstract:
The invention relates to a dipping cap comprising a filament for a dual-filament lamp. The dimension between an outlet of an outgoing section of the filament, on the side of the base, and the point on the outgoing section of the filament, arranged opposite the outgoing section of the filament on the side of the base and welded to the dipping cap, measures more than approximately 5.2 mm and less than 9.7 mm, and the dimension between the outlet of the outgoing section of the filament, on the side of the base, and the front surface of the dipping cap, which is adjacent to the outgoing section of the filament, welded to the dipping cap, measures more than approximately 5.9 mm and less than 11.9 mm.

Description:
TECHNICAL FIELD 
       [0001]    The invention is based on an anti-dazzle device with a filament for two-filament lamps which are used in particular in vehicle headlamps. 
       PRIOR ART 
       [0002]    A two-filament halogen incandescent lamp which has a lamp bulb which has a tight pinch seal at one end, which pinch seal is fixed in clamping fashion in a holder part made from stainless steel, is known from the publication WO 98/38670. Two incandescent filaments, which can be connected to a lamp base overall via three fused-in power supply lines or via molybdenum foils and power supply lines connected thereto, are located within the lamp bulb. 
         [0003]    The incandescent filament  1  of this halogen incandescent lamp, which incandescent filament is shown in  FIG. 1  and is provided adjacent to the lamp cover, is provided with an anti-dazzle device  2 , which has a welding lug  6  provided with a transverse rib  4 . An outgoing filament end  8  extends from the incandescent filament  2  to the welding point  10  at which the outgoing filament end  8  can be welded to the transverse rib  4  by means of projection welding. 
         [0004]    The distance between a point at which a base-side outgoing filament end (not shown in  FIG. 1 ) emerges from the filament  2  and the welding point  10  has the dimension A of 9.7 mm, while the distance between the point at which the base-side outgoing filament end emerges from the filament  2  and the end face of the welding lug  6  has the dimension B of 11.9 mm. 
         [0005]    The anti-dazzle device shown in  FIG. 1 , which is in particular used in H4 lamps, is responsible for the light/dark boundary. The anti-dazzle device  2  is produced from sheet molybdenum. 
       DESCRIPTION OF THE INVENTION 
       [0006]    The object of the present invention is to provide an anti-dazzle device with a filament for a two-filament lamp, in which it is possible to achieve a reduction in costs, precise determination of the filament position and low transmission losses. 
         [0007]    This object is achieved by an anti-dazzle device with a filament as claimed in claim  1 . 
         [0008]    Particularly advantageous configurations are given in the dependent claims. 
         [0009]    The invention provides an anti-dazzle device with a filament for a two-filament lamp, the dimension between a point at which a base-side outgoing filament end emerges from the filament and the point on the outgoing filament end which is arranged opposite the base-side, outgoing filament end and is welded to the anti-dazzle device being between approximately 5.2 mm and less than 9.7 mm, and the dimension between the point at which the base-side outgoing filament end emerges from the filament and the end face of the anti-dazzle device, which is adjacent to the outgoing filament end, at which the outgoing filament end is welded to the anti-dazzle device, being between approximately 5.9 mm and less than 11.9 mm. An anti-dazzle device which is optimized in terms of costs and quality can therefore be used, in particular when the anti-dazzle devices are not responsible for the light/dark boundary in vehicle headlamps. 
         [0010]    It is preferred that the anti-dazzle device is connected to the outgoing filament end by means of projection welding. It is thus possible to use a reliable joint between the parts to be welded without any additional material and therefore without additional material being introduced. 
         [0011]    It is preferred if the welding projection on the anti-dazzle device for the projection welding has, in cross section, the form of a ring segment, preferably with an angle of 90°. The welding lug of the anti-dazzle device can therefore be modified in a simple manner by introducing a transverse rib and it is possible for outgoing filament ends to be attached with any desired relative position in relation to the transverse rib. 
         [0012]    In a preferred embodiment, a planar face of the anti-dazzle device is connected to the outgoing filament end. In this way, the outgoing filament end can extend parallel to the longitudinal axis of the filament and a uniform distance between the filament and the bottom of the anti-dazzle device can be used. 
         [0013]    In a development according to the invention, the anti-dazzle device with a filament is designed for a halogen incandescent lamp for a vehicle headlamp, with the result that the use in daytime running lights is possible, for example. 
         [0014]    In addition, it is preferred if the two-filament lamp is a two-filament headlamp since in this way it is possible to realize a lower beam and an upper beam or an upper beam and a daytime running light in one lamp. 
         [0015]    In addition it is preferred if the two-filament lamp is a two-filament halogen lamp since, in this way, it is possible to produce a particular luminous intensity with excellent light quality. 
         [0016]    In one development, a headlamp with a lamp is provided which has an anti-dazzle device with a filament, wherein a shield is responsible for the light/dark boundary outside of the lamp vessel of the two-filament lamp and in the space delimited by the reflector. This takes into account the circumstance in which the preferred tolerances for the assembly comprising the anti-dazzle device and the filament in lamps can be used particularly well when the light/dark boundary is realized by a mechanically actuated shield in the interior of the vehicle headlamp. As a result, the daytime running light and the upper beam can be produced by the two filaments of the lamp, while the lower beam is produced by means of the shield. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The invention will be explained in more detail below with reference to three exemplary embodiments. In the figures: 
           [0018]      FIG. 1  shows an anti-dazzle device with a filament in accordance with the prior art, 
           [0019]      FIG. 2  shows a halogen incandescent lamp which has been provided with a lamp base for a vehicle headlamp, in which the present invention can be used, 
           [0020]      FIG. 3  shows an anti-dazzle device with a filament corresponding to the first exemplary embodiment, 
           [0021]      FIG. 4  shows an anti-dazzle device with a filament corresponding to the second exemplary embodiment, and 
           [0022]      FIG. 5  shows an anti-dazzle device with a filament corresponding to the third exemplary embodiment. 
       
    
    
     PREFERRED EMBODIMENT OF THE INVENTION 
       [0023]      FIG. 2  shows a halogen incandescent lamp  22  which has been provided with a lamp base  20  for a vehicle headlamp. 
         [0024]    The halogen incandescent lamp  22  has a vitreous, substantially cylindrical lamp vessel  24 , with two incandescent filaments  26 , arranged in the interior of said lamp vessel, which incandescent filaments 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  26 ,  28  are in the form of tungsten wires with a single or double coil, for example. 
         [0025]    The outgoing filament ends  30 ,  32  of the filament  26  and the outgoing filament ends  34 ,  36  of the filament  28  preferably have a molybdenum foil wound around them, which molybdenum foil acts as a welding aid when welding the outgoing filament ends to the power supply lines for the incandescent filament. A sealed-off end  38  of the lamp vessel  24  is anchored in the lamp base  20 . The lamp vessel dome  40 , which is remote from the lamp base  20 , can be provided with an opaque coating  40 . The incandescent filament  26  which is provided adjacent to the lamp vessel dome  40  is arranged adjacent to an anti-dazzle device  42 , which is shaped from sheet molybdenum. 
         [0026]    The anti-dazzle device  42  and the incandescent filament  62  are emphasized by being enlarged in the illustrations in  FIGS. 3 ,  4  and  5 . 
         [0027]    The outgoing filament end  30 , which points towards the opaque coating  40 , of the incandescent filament  26  is welded to the anti-dazzle device  42  in a peripheral region thereof, while the bottom of the trough-like anti-dazzle device  42  is welded to a power supply line  44 . The outgoing filament end  32  of the incandescent filament  26  and the outgoing filament end  34  of the incandescent filament  28  are welded to a power supply line  46 , while the outgoing filament end  36  of the incandescent filament  28  is welded to a power supply line  48 . 
         [0028]    The three power supply wires  44 ,  46 ,  48  are fixed via two quartz glass webs  50 , which are fused with one another, with the result that the power supply lines  44 ,  46 ,  48  are arranged in one plane. When using hard glass, the power supply lines  44 ,  46 ,  48  pass through the sealed-off end  38  of the lamp vessel  24  and are in electrical contact with a contact lug  52 ,  54 ,  56  on the lamp base  20 . Molybdenum foils are provided in the pinch seal in quartz glass. The three contact lugs  52 ,  54 ,  56  protrude laterally out of the lamp base  20  in relation to the mid-axis of the lamp vessel  24  and form the electrical terminals of the halogen lamp. 
         [0029]    A design of the anti-dazzle device with the filaments, for example for an above described two-filament lamp, will be described below with reference to the first exemplary embodiment in  FIG. 3 .  FIG. 3  shows the anti-dazzle device  62 , which is illustrated merely schematically by the reference symbol  42  in  FIG. 2 , in a side view. 
         [0030]    The anti-dazzle device  62  has a trough-like section  64 , which can be stabilized, for example, by at least one rib (not illustrated in the figures). The welding lug  6  is connected to the trough-like section  64  via a connecting bevel  66  of the trough-like section  64  and has a transverse rib  70 , via which the outgoing filament end  30  of the incandescent filament  26  can be welded to the anti-dazzle device  62 .  FIG. 3  does not illustrate the outgoing filament end  32 , but merely the location at which the base-side outgoing filament end  32  emerges from the filament  26 . 
         [0031]    The distance between the welding point  72  of the outgoing filament end  30  with the transverse rib  70  and this point at which the base-side outgoing filament end  32  emerges from the filament  26  is denoted by A, while the distance between the end face  74  of the welding lug  68  and the point at which the base-side outgoing filament end  32  emerges from the filament  26  is denoted by B. The magnitude of the distance between the point at which the base-side outgoing filament end emerges from the filament and the base is denoted by the e dimension, corresponding to ECE R37. The magnitude of the distance A can be reduced to below 9.7 mm down to 5.2 mm from the 9.7 mm which is known for the H4 lamp depending on the requirements in terms of stamping, bending and deep-drawing. By shortening the end section of the welding lug  68 , the magnitude of the distance B is reduced from the 11.9 mm known for the H4 lamp to below 11.9 mm down to 5.9 mm. 
         [0032]    As a result, the anti-dazzle device  62  can be realized with a substantially smaller longitudinal dimension, with the result that, owing to the reduction in the quantity of material used for the cover, for example molybdenum, a noticeable reduction in costs can be achieved in the case of the anti-dazzle device with a filament corresponding to the present invention. 
         [0033]    Since the outgoing filament end  30  which is also lit can be shortened, there is less parasitic light and lower bending moments can occur during welding, with the result that the position of the incandescent filament  26  can be determined more precisely than was previously the case. 
         [0034]    Owing to the shorter outgoing filament end  30  and the reduced dimensions of the anti-dazzle device  62 , the total resistance of this system is reduced and this results in lower transmission losses. In addition, a lower thermal capacity can be attributed to the reduced dimensions, with the result that the lamp starts up more quickly. The reduced dimensions furthermore bring about an increase in the resistance to vibrations. 
         [0035]      FIG. 4  shows an anti-dazzle device  82  with a filament  26  corresponding to the second exemplary embodiment. 
         [0036]    The anti-dazzle device  82  differs from the anti-dazzle device of the first exemplary embodiment by the welding lug  84 . The welding lug  84  has a transverse rib  86 , but, in contrast to the transverse rib  70  of the first exemplary embodiment, which has the form of a hollow cylinder halved at the longitudinal axis, has the shape of a hollow cylinder which has been quartered at the longitudinal axis, in cross section. As is also the case of the first exemplary embodiment, the welded joint  88  is formed by means of projection welding. 
         [0037]    Since part of the longitudinal dimension of the welding lug from the first exemplary embodiment is no longer required in the second exemplary embodiment, there is a reduced dimension B from the end face  90  of the welding lug  84  to the point at which the base-side outgoing filament end  32  emerges from the filament  26 , with the dimension B being equal to the dimension A since the welded joint  88  is located at the end face  50 .  FIG. 5  shows an anti-dazzle device  92  corresponding to the third exemplary embodiment, where the welding lug  94  has a flat surface  96 . The outgoing filament end  30  therefore rests on the surface  94  and is welded thereto. In this case, in the same way as in the second exemplary embodiment shown in  FIG. 4 , it is preferred for the welded joint  98  to be arranged at the end face  100 , with the result that the dimensions A and B are identical in the third exemplary embodiment as well. 
         [0038]    With the present invention corresponding to one of the three exemplary embodiments, it is possible to achieve an anti-dazzle device which has been optimized in terms of costs and quality for an incandescent filament, which anti-dazzle device can be used for a reduced longitudinal dimension of the lamp bulb  24  even when the filament has the same distance as in the prior art. 
         [0039]    The invention describes an anti-dazzle device with a filament for a two-filament lamp. In this case, the dimension between a point at which a base-side outgoing filament end emerges from the filament and the point on the outgoing filament end which is arranged opposite the base-side outgoing filament end and is welded to the anti-dazzle device is between approximately 5.2 mm and less than 9.7 mm, and the dimension between the point at which the base-side outgoing filament end emerges from the filament and the end face of the anti-dazzle device, which is adjacent to the outgoing filament end, at which the outgoing filament end is welded to the anti-dazzle device, is between approximately 5.9 mm and less than 11.9 mm.