Abstract:
An automotive headlamp bulb provides the two light or three filament sources in a single bulb. One source may be used to generate a standard headlamp beam, while the second source may be used to generate an augmenting side beam in response to a turning signal. A similar third filament may provide an augmenting beam to the opposite side, or farther to the same side. The single bulb eliminates the need for a second bulb, or a second reflector in an advanced headlamp system with turning light augmentation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    not applicable 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to electric lamps and particularly to electric lamps. More particularly the invention is concerned with lamps with a plurality of enclosed filaments. 
         [0004]    2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98 
         [0005]    Advanced forward lighting headlamp systems (AFS) are being developed to light the road on the side a vehicle is turning to. The first AFS headlamp systems used one lamp and one reflector or projector lens. The beam control was achieved by rotating the entire lamp to the right or left with a stepper motor. This is a mechanically complex and expensive system. Alternative systems were devised using a first lamp to generate a forward beam and a second lamp to generate an augmenting side beam in response to a turning signal. By tuning between the two sources one can aim the beam. The two lamp AFS systems may use either or both two light sources, and two reflectors. The cost of the extra material for the lamps and the reflectors, the space and volume for the second lamp, and the additional labor in mounting, and aiming the duplicative systems makes the enhanced lighting system expensive. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    An incandescent lamp capsule may be made with an envelope having a light transmissive wall defining an enclosed volume, and a lamp axis. A first filament is positioned in the enclosed volume having a first filament axis. The first filament is oriented so the first filament axis is in an axial plane parallel with the lamp axis. A second filament is also positioned in the enclosed volume, defining a second filament axis. The second filament is oriented so the second filament axis is in the axial plane; and the second filament axis is not parallel to the first filament axis. A third filament is positioned in the enclosed volume, defining a third filament axis. The third filament is oriented so the third filament axis is in the axial plane with the first filament axis and the second filament axis. The third filament axis is not parallel to the first filament axis, and the third filament axis is not parallel to the second filament axis. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0007]      FIG. 1  shows a schematic view of an advanced forward lighting system. 
           [0008]      FIG. 2  shows a schematic view of a preferred embodiment of a bending beam headlamp with a multi-filament bulb. 
           [0009]      FIG. 3  shows a schematic view of a preferred embodiment of an alternative multi-filament arrangement for a bending beam headlamp. 
           [0010]      FIG. 4  shows a detailed schematic view of an alternative embodiment of a multi-filament arrangement for a bending beam headlamp. 
           [0011]      FIG. 5  shows a perspective view of an alternative automotive headlamp bulb with a multi-filament arrangement for a bending beam headlamp. 
           [0012]      FIG. 6  shows a schematic view of an alternative embodiment of a multi-filament arrangement for a bending beam headlamp. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]      FIG. 1  shows a schematic view of an advanced forward lighting system  10 .  FIG. 2  shows a schematic view of a preferred embodiment of a bending beam headlamp with a multi-filament bulb. A steering device  12  provides a signal  14  indicating desired movement of a vehicle relative to the road. The steering signal  14  is used by a controller  16  to alter the power supplied  18  to an improved lamp capsule  20  held in a reflector  22  directing light into a beam pattern  24 . The lamp capsule  20  has a first filament  50  to generate a forward beam pattern  28 . The lamp capsule  20  also has a second filament  60  to generate augmenting a first (right) side illumination  32 . The lamp capsule  20  may also have a third filament  70  to generate augmenting second (left) side illumination  30 . 
         [0014]      FIG. 2  shows a perspective view of a preferred embodiment of a bending beam headlamp with multi-filament capsule. The lamp includes an envelope with a light transmissive wall, defining an enclosed volume. In the enclosed volume is a plurality of filaments. The lamp is generally used with a reflector. The reflector  22  may be any of numerous headlamp reflectors. In particular, the reflector  22  may be a hollow, plastic shell with an aluminized interior surface shaping the light from the lamp into a vehicle headlamp beam. 
         [0015]    Enclosed in the envelope volume is a first filament  50  extending along a first axis  52 . The first filament  50  may be a straight wire extending as the axis  52 ; a wire coiled around the axis  52 , a coiled coil extending along the axis  52 , or similarly formed linearly extending filament structure. In general, the first filament  50  is linearly extended along the first axis  52 , and is symmetrically disposed about the first axis  52 , to form an approximately cylindrical filament structure. The first filament has a first electrical connection  54  and a second electrical connection  56 . The first filament is mechanically and electrically supported between a first support  58  and a second support  59 . 
         [0016]    Enclosed in the volume is a second filament  60  extending along a second axis  62 . The second filament  60  may also be a straight wire extending as the second axis  62 , a wire coiled around the second axis  62 , a coiled coil extending along the second axis  62 , and so on in the same pattern. In general, the second filament  60  is linearly extended along the second axis  62 , and is symmetrically disposed about the second axis  62 . The first axis  52  and the second axis  62  are in a common plane, but are not parallel. The second filament  60  then extends in a common plane (Actually the filaments are in a common parallel planar slice that is co-planar with their respective axes. The slice has a width equal to the filament diameter, but for convenience the filaments will be said to be “parallel” or in a common plane.) with the first filament  50 , but in a direction with at least a component direction that is perpendicular to the first axis  52 . The second filament has a first electrical connection  64  and a second electrical connection  66 . The right side filament  60  is coupled mechanically and electrically between the third support  68  and a fourth support  69 . In one preferred embodiment, the right side filament  60  forms a right angle with the first filament  50  at the rear end of the first filament  50 . The second filament  60  is then substantially behind the first filament  50  (closer to the base  82 ), minimizing interference with the function of the first filament  50 . 
         [0017]    Enclosed in the volume is a third filament  70  extending along a third axis  72 . The third filament  70  may also be a straight wire extending as the third axis  72 , a wire coiled around the third axis  72 , a coiled coil extending along the third axis  72 , and so on in the same pattern. In general, the third filament  70  is linearly extended along the third axis  72 , and is symmetrically disposed about the third axis  72 . The first axis  52  and the third axis  72  are in a common plane but are not parallel. The third filament  70  then extends in a common plane (actually in a planar slice with a width of the filament diameter) with the first filament  50 , but in a direction with at least a component direction that is perpendicular to the first axis  50 . The third filament  70  has a first electrical connection  74  and a second electrical connection  76 . The left side filament is coupled mechanically and electrically between the fifth support  78  and a sixth support  79 . The third filament  70  may form a right angle with the first filament  50  at the rear end of the first filament  56 . The third filament  70  is then substantially behind the first filament  50  (closer to the base  82 ) minimizing interference with the function of the first filament  50 . 
         [0018]    The first support  58 , second support  59 , third support  68 , fourth support  69 , fifth support  78 , sixth support  79  may be captured in a glass bridge  80 , and then extended through a press sealed end  82  of the lamp envelope for electrical connection on the lamp exterior. The second support  59 , fourth support  69  and sixth support  79  may be combined (pairwise or as a triple) to form a single support (common electrical supply). 
         [0019]      FIG. 3  shows a schematic view of a preferred embodiment of an alternative multi-filament arrangement for a bending beam headlamp.  FIG. 4  shows a detailed schematic view of a preferred embodiment of a multi-filament arrangement for a bending beam headlamp. The first filament  100  is a coiled wire axially  102  aligned with a front end facing the field to be illuminated, and rear end facing a base  132 . The first filament  100  is mechanically and electrically supported between a first support  104  and a second support  106 . Roughly perpendicular to the first filament  100  is a right side filament  110 . The right side filament  110  is a coiled wire whose axis  112  that is angled forward at an angle of 80 degrees to the first filament axis  102 . The right side filament  110  is coupled mechanically and electrically between the second support  114  and in common with the second support  106 . The right side filament  110  forms an 80-degree angle with the first filament  100  at the rear end of the first filament  100 . Roughly perpendicular to the first filament  100  is a left side filament  120 . The left side filament  120  is a coiled wire whose axis  122  is similarly angled forward at an angle of 80 degrees to the first filament axis  102 . The left side filament  120  is coupled mechanically and electrically between a second support  124  and in common with the second support  106 . The left side filament  120  forms an 80-degree angle with the first filament  100  at the rear end of the first filament  110 . The first support  104 , second support  106 , third support  114 , and fourth support  116  may be captured in a glass bridge  130 , and then extended through a press sealed  132  end (base end) of the lamp envelope for electrical connection on the lamp exterior. 
         [0020]    The lamp is operated by supplying electrical energy to the first filament to generate light. The light generated by the first filament ( 50 ,  100 ) is then directed by the reflector to be centered about a desired point in the field to be illuminated. When the vehicle is steered under a first condition to a one side relative to the beam generated by the first filament ( 50 ,  100 ), a first turning signal is generated that is used to signal the supply of electrical energy to the second filament ( 60 ,  110 ). The actual first turning signal may be generated as a function of one or more steering factors such as an absolute change, a rate of change, a duration of change, a time integrated change, some other signal indicating a change in the vehicle relative to the environment or a computed combination of such factors. The vehicle condition change signal is then used to drive the electrical energy supplied to the second filament ( 60 ,  110 ) or to the third filament ( 70 ,  120 ). For example, if the vehicle is turned to the right, the second filament ( 60 ,  110 ) located on the left of the first filament is turned on to generate light that is then reflected by the reflector to the right side (assuming an inverting reflector) of the beam pattern generated by the first filament ( 50 ,  100 ) and the reflector. It is understood there may be beam over lap between the reflected beam from the first filament, and the reflected beam from the second filament. The sensed actual turn on signal may be conditioned by other computed factors, such as the angle of turn, rate of turn, duration of turn angle, vehicle speed of or other measured or computed factors. The light from the second filament ( 60 ,  110 ) then further illuminates the right side of the field to be illuminated in the region where the vehicle is turning to. The third filament ( 70 ,  120 ) may be farther to the left of the first filament and the second filament ( 60 ,  110 ), and is sequentially illuminated when the turning factors indicate still more light is needed even farther to the right, for example when a particularly sharp turn is made and extra light is desired far to the side of the first beam pattern. Alternatively, the third filament ( 70 ,  120 ) may be located on the right side of the first filament ( 50 ,  100 ), which is on the opposite side of the first filament ( 50 ,  110 ) relative to the second filament ( 60 ,  110 ). The third filament ( 70 ,  120 ) may then be similarly connected to be illuminating when a left turn (opposite to a right turn) is sensed. Again the third filament ( 70 ,  120 ) may respond to the turn angle, the rate of turn, the duration of the turn a so on. In this way the main beam of the first filament is supplemented by the light from the second or third filaments, directed substantially in the same plane or planes, as is light for the first filament, but to a side of the center of the beam from the first filament.  FIG. 5  shows a perspective view of an alternative automotive headlamp bulb with a multi-filament arrangement for a bending beam headlamp. 
         [0021]      FIG. 6  shows a schematic side view of an alternative AFS lamp  300 . The main filament  310  is axially aligned and centered in the forward end of the envelope  312  supported from two leads  314 ,  316 . The right filament  318  and the left filament  320  are axially aligned, and offset sequentially rearward of the main filament  310  along the axis. The right filament  318  and left filament  320  may be share a lead with the main filament  310  for mechanical and electrical coupling. The right filament  318  and left filament  320  may be offset side to side from the main axis. The right filament  318  and left filament  320  may also be tilted with respect to the main axis. 
         [0022]      FIG. 6  shows a schematic view of an alternative AFS lamp  400 . The main filament  410  is axially aligned in the forward end of the envelope  412  supported from two leads  414 ,  416 . The second filament  418  and the third filament  420  are radially aligned in sequence rearward of the main filament  410 . The second filament  418  and third filament  420  may be share a lead ( 416 ) with the main filament  410  for mechanical and electrical coupling. The second filament  418  and third filament  420  may be offset from the main axis. The second filament  418  and third filament  420  may also be tilted with respect to the main axis. The second filament is show to be perpendicular to the main filament  410 , while the third filament  420  is shown to be at an angle to both the main filament  410  and the second filament  418 . In operation, with both augmenting filaments ( 418 ,  420 ) on one side of the main filament  410 , the main filament  410  is operated to generate a center beam pattern. With a moderate turn to one side, the second filament  418  is additionally illuminated providing more light to one side of the center beam. With a greater turning, the third filament  420  is illuminated providing additional light farther to one side of the main beam. The vehicle then may be equipped to either two headlamps each with center, right augmentation and left augmentation filaments; or one right headlamp with a center, soft right augmentation and hard right augmentation filaments and one left headlamp with center, soft left augmentation and hard left augmentation filaments. 
         [0023]    It is understood the main filament axis need not be axially centered along the main axis of the envelope, but may be radially offset from the main envelope axis. It is also understood that the lamp may be reoriented with respect to the field to be illuminated by restructuring the headlamp reflector accordingly. In general the second filament and the third filament may be positioned around the lamp axis in any position, given that the associated surrounding reflector directs the associated light appropriately to the right and left sides of the filed to be illuminated accordingly. One simple variation is to rotate the lamp 180 degrees, and rework the reflector to project the light from right (now left) and left (now right) side filaments across the beam axis line to the respective opposite sides of the illuminated field. More complex redirections can be achieved with a vertical orientation, that is changing from a 3 o&#39;clock to 9 o&#39;clock orientation to a 12 o&#39;clock to 6 o&#39;clock orientation or any intermediate orientation. While there have been shown and described what are at present considered to be the preferred embodiments of the invention, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope of the invention defined by the appended claims.