Abstract:
A bifunctional headlamp having a bulb shield operable to project a low beam light pattern or a high beam light pattern. A bulb shield surrounds a bulb inside a housing. The bulb shield is attached to an actuator, which rotates the bulb shield about the bulb. The bulb shield contains projections placed opposite one another on the bulb shield, which serve to selectively shield portions of emitted light from the bulb from reflecting out of the housing. The selective shielding of the light emitted from the housing allows the bifunctional headlamp to utilize one bulb for both a low beam pattern and a high beam pattern. The use of one bulb for two functions reduces complexity and electrical requirements.

Description:
BACKGROUND  
         [0001]    Automobiles are required to include headlamps which include both low beam and high beam light patterns for low-light driving. A low beam pattern projects light from the headlamp downwardly, onto a road surface. The low beam pattern is specifically arranged to project a minimum of light into oncoming traffic, and is designed for general use when other automobiles may be nearby. A high beam pattern is typically used in conjunction with the low beam pattern, and projects light further onto the road, illuminating surrounding areas of the road surface, both of which allows the automobile driver an enhanced field of view over the low beam pattern. The high beam pattern is not used in situations where other automobiles are on the road ahead, as the high beam pattern projects light into oncoming traffic, which creates an unsafe driving condition. Thus, the automobile driver may utilize the high beam pattern to increase safety on an unused area of roadway, and the low beam pattern when negotiating oncoming traffic or following another automobile.  
           [0002]    Manufacturers may provide low beam and high beam patterns by utilizing separate headlamp assemblies and/or reflectors to project each. In this instance, a low beam headlamp/reflector is energized to provide a low beam pattern. When high beam functionality is desired, a high beam headlamp/reflector is energized, in addition to the low beam headlamp, to provide the additional high beam pattern.  
           [0003]    Further, a manufacturer may provide two bulbs with one reflector in a headlamp assembly with one bulb oriented to provide a low beam pattern, and a second bulb oriented to provide a high beam pattern. The bulb which produces the high beam pattern may thus be selectively energized to provide high beam functionality.  
           [0004]    In the above examples, two bulbs are required to provide low and high beam patterns for one side of the automobile. The use of the high beam doubles the electrical requirements of the headlamp lighting system, which places an additional burden on the automobile&#39;s electrical system. Additionally, the use of two bulbs requires the use of additional electrical wiring and mechanical attachments, which increases the complexity of the headlamp assembly.  
           [0005]    A desirable feature of a headlamp would be a mechanism to allow a single bulb to provide both a low beam pattern and a high beam pattern. A single bulb reduces the overall electrical demands of the automobile, which serves to increase efficiency. A single bulb also allows for a smaller, less complex, and more compact footprint of the headlamps on the front of the automobile. A smaller headlamp footprint may be useful in itself, to allow automobile manufacturers a greater ability to add stylization to the front of the automobile, which in turn may attract consumer interest.  
         SUMMARY  
         [0006]    A bifunctional headlamp comprises a housing and a frame attached to the housing. A lamp is positioned within the housing. A reflector is formed on the inside surface of the housing. Attached therein to the frame is an actuator. The actuator operates an actuator shaft, integral with and extending from the actuator. The actuator may be comprised of an electric motor or a rotary solenoid, operable to rotate the actuator shaft, such that rotation of the actuator shaft results in rotation of the bulb shield about the bulb. The electric motor may optionally be a stepper-type electric motor, capable of operating on the actuator shaft to rotate the actuator shaft in discrete rotational increments. The actuator shaft is in communication with a bulb shield. The bulb shield is essentially cylindrical, and comprises two projections arranged on the bulb shield 180 degrees apart. The two projections may be semi-circular, or may be of a shape necessary to create a desired light pattern on the reflector surface. The bulb shield partially surrounds the bulb, and contains a central axis, which intercepts the bulb. Rotation of the actuator shaft results in rotation of the bulb shield about the bulb. While rotating, the central axis of the bulb shield remains intercepted with the bulb. Rotation of the bulb shield reorients the bulb shield with respect to the bulb. The reorientation changes the position of the semi-circular projections, and selectively blocks light from the bulb from striking the reflector. The selective blocking of light emitted from the bulb allows two patterns of light to be emitted from the headlamp; a first pattern for low beam light emission, and a second pattern for high beam light emission. In this way, a single bulb may be utilized to project both low beam and high beam patterns from the headlamp. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a side view of a bifunctional headlamp;  
         [0008]    [0008]FIG. 2A is a top cross sectional view of the bifunctional headlamp along the line A-A of FIG. 1, projecting light in a low beam pattern;  
         [0009]    [0009]FIG. 2B is a top cross sectional view of the bifunctional headlamp along the line A-A of FIG. 1, projecting light in a high beam pattern;  
         [0010]    [0010]FIG. 3A is a rear perspective component view of the bulb shield of FIG. 1;  
         [0011]    [0011]FIG. 3B is a side perspective component view of the bulb shield of FIG. 1;  
         [0012]    [0012]FIG. 4A is a top component view of the bulb shield and the bulb along line D-D of FIG. 1;  
         [0013]    [0013]FIG. 4B is a view of FIG. 4A, with the bulb shield rotated ninety degrees clockwise about the bulb; and  
         [0014]    [0014]FIG. 5 is a front view of the reflector of a bifunctional headlamp along the line B-B of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0015]    One embodiment of a bifunctional headlamp containing a rotating shield with integral actuator is provided as shown in FIG. 1, and is generally indicated as numeral  18 . The bifunctional headlamp  18  comprises a bulb  28  positioned within a housing  22 . A bulb shield  32  is positioned about the bulb  28 . A shield support  38  is attached to the bulb shield  32 , and the shield support  38  is attached to an actuator shaft  44 . An actuator  42  is operable on an actuator shaft  44  to rotate the bulb shield  32  about the bulb  28 . Rotation of the bulb shield  32  about the bulb  28  serves to vary the light pattern emitted from the bifunctional headlamp  18  from a low beam pattern to a high beam pattern.  
         [0016]    The outside of the bifunctional headlamp  18  is formed from the housing  22  and a lens  20 . The housing  22  contains a first housing opening  50  and a second housing opening  52 . The first housing opening  50  is dimensioned to receive a standard electrical socket  26  and bulb  28  for headlamps. The second housing opening  52  is a comparable diameter to the lens  20 . The walls of the housing  22  at the second housing opening  52  and the lens  20  abut one another, and are sealed together. The seal may be accomplished in one of a number of ways known in the art. The union of the housing  22  and the lens  20  defines a cavity  24  where the bulb is positioned. The lens  20  is manufactured from a transparent material, and may optionally have optics integrated into the lens  20 , which serve to focus or angle emitted light rays. The lens  20  may optionally be made from a material which allows light of a certain wavelength or range of wavelengths to pass, therefore imparting a distinct color to light radiated outside of the bifunctional headlamp  18 . A reflector  66  is formed on the inside surface of the housing  22 . The reflector  66  faces the cavity  24 , and is formed by coating a portion of the inside housing  22  with a material which reflects light rays. Techniques for coating the inside surface of the housing  22  with a reflective material, or optionally for forming the housing  22  out of a reflective material, are well known in the art. Of course, the reflector  66  may need not be formed as part of the housing, and may be provided as separate from the housing and positioned within the housing.  
         [0017]    The bulb  28  plugs into a standard electrical socket  26 . The electrical socket  26  is releasably attached to the housing  22  at the first housing opening  50 . When the electrical socket  26  is attached to the housing  22 , the bulb  28  enters the cavity  24  through the first housing opening  50 . The electrical socket  26  provides an electrical attachment point to the automobile&#39;s electrical system. The concept of an electrical socket  26  and bulb  28  is well understood and practiced in the art. Of course, the bulb  28  may be any of the headlamp bulbs known in the art, for example, incandescent, halogen, high-intensity gas discharge, or one or more light-emitting diodes.  
         [0018]    The frame  30  is essentially cylindrical with one or more leg portions  64  extending therefrom. The frame legs  64  are attached to the housing  22  by welding or other means known in the art, such that the frame  30  extends into the cavity  24  created by the union of the housing  22  and the lens  20 , and partially surrounds the bulb  28 . The frame  30  is made from a rigid material, and is used as an attachment point for components within the cavity  24 .  
         [0019]    Opposite the side of the actuator  42  which contains the plurality of actuator retaining posts  45 , the actuator  42  abuts an actuator support  40 . The actuator support  40  is fixed to the inside of the frame  30 , and further prevents movement of the actuator  42  along the C′ axis. The actuator support  40  is essentially circular, and is of a similar diameter to the inner diameter of the frame  30 . An opening  68  is located in the center of the actuator support  40 , which is of a greater diameter than the diameter of the actuator shaft  44 . The actuator shaft  44  extends through the opening  68  in the actuator support  40  such that the actuator support  40  and the actuator shaft  44  are concentric. In one embodiment, the actuator support  40  may alternately be fixed to the actuator  42  and designed and dimensioned to fit snugly within the frame  30  to assure proper installation and orientation of the actuator  42  into the frame  30 .  
         [0020]    The actuator  42  is attached to the frame  30 . In the disclosed embodiment, the actuator comprises an electric motor comprising an actuator shaft  44 . However, the actuator may be any of several devices such as a rotary solenoid operable to rotate an integrated shaft, or a linear solenoid connected to a rotating drive mechanism. In one embodiment, the actuator  42  may be a “stepper” type motor, which operates on the actuator shaft  44  to rotate the actuator shaft  44  to discrete angular positions, particularly, ninety degrees of rotation. The actuator  42  may be essentially cylindrical, and the outer diameter of the actuator  42  is of a similar diameter to the inner diameter of the frame  30 . The rear of the actuator  42  contains one or more actuator retaining posts  45 , which extend through openings in the frame  30 . One or more actuator fasteners  46  secure the extensions of the one or more actuator retaining posts  45 . The actuator  42  is connected to electrical leads (not shown), which distribute electricity from the automobile&#39;s electrical system to the actuator  42 , through a headlamp control system (not shown). The actuator  42  operates, upon the application of an electric current, to rotate an actuator shaft  44  about the C′ axis.  
         [0021]    The shield support  38  is essentially circular, and is of a smaller diameter than the inner diameter of the frame  30 ,. The shield support  38  is attached to the end of the actuator shaft  44  which extends through the actuator support  40 , such that rotation of the actuator shaft  44  results in an equal amount of rotation of the shield support  38 . The shield support  38  provides a secure attachment point for the bulb shield  32  to the actuator shaft  44 , and also serves as the primary insulator of the actuator  42 , to shield the actuator  42  from thermal energy produced by the bulb  28 . The actuator support  40  functions as a secondary actuator  42  insulation device.  
         [0022]    The bulb shield  32  is attached to the shield support  38 . As shown in FIGS. 3A and 3B, the bulb shield  32  is essentially cylindrical, and the outer diameter of the bulb shield  32  is smaller than the inner diameter of the frame  30 . Referring again to FIG. 1, the bulb shield  32  is positioned around the bulb  28  such that the central axis of the bulb shield  32  intercepts the bulb  28 . The bulb shield  32  contains two roughly semi-circular projections  36 , formed on one end of the bulb shield  32  and 180 degrees opposite one another, which extend into the cavity  24 . The projections  36  are positioned about the bulb  28 , such that the projections  36  shield the bulb  28  from projecting light onto certain portions of the reflector  66 . In an alternate embodiment of the present invention, the bulb shield  32  is essentially cylindrical, and contains projections  36  which are arranged asymmetrically about the bulb shield  32 . In the alternate embodiment, the projections  36  may have different individual shapes, so that an asymmetric beam pattern may be emitted from the lamp assembly  18 .  
         [0023]    [0023]FIG. 4A shows a top component view of the bulb shield  32  and the bulb  28  along the D-D line of FIG. 1 (i.e., the bulb shield and bulb from FIG. 2A). As shown in FIG. 4A, the projections  36  are positioned along the sides of the bulb  28 . FIG. 4B shows the bulb shield  32  and the bulb  28  of FIG. 4A, with the bulb shield  32  rotated ninety degrees about the X axis shown in FIG. 4B (i.e., the bulb shield and bulb from FIG. 2B). The bulb shield  32  of FIG. 4B shows the bulb shield  32  with the projections  36  positioned along the top and bottom with respect to the bifunctional headlamp  18 . FIGS. 4A and 4B show the bulb  28  positioned along the cylindrical axis of the bulb shield  32 . As shown in FIG. 4A, the point source of light  29  of the bifunctional headlamp  18  is fully viewable between projections  36  from the top view. As shown in FIG. 4B, with the bulb shield  32  rotated ninety degrees, the top view results in the point source of light  29  of the bulb  28  being partially covered by the bulb shield  32  (i.e. obstructed from view by one of the projections  36  of the bulb shield  32 ). The point source of light may comprise any number of different light sources, including the filament of an incandescent bulb, the electric arc of a high intensity discharge bulb, or from the diode of a light emitting diode, depending on the type of bulb used. It should be noted that since the two projections  36  are opposite one another, a 180 degree rotation of the bulb shield  32  about the bulb  28  as shown in FIG. 4A yields the same view as in FIG. 4A, and a 270 degree rotation of the bulb shield  32  about the bulb  28  as shown in FIG. 4A yields the view of FIG. 4B. Thus, a ninety degree rotation of the bulb shield  32  about the bulb  28 , in either the clockwise or counterclockwise direction, yields alternating views of the bulb  28  and the bulb shield  32  exemplified by FIGS. 4A and 4B. In an alternate embodiment which includes a bulb shield  32  having asymmetrical projections  36 , as described above, the bulb shield  32  may not be rotated in ninety degree increments, but may occur over another discrete angle. Also, an asymmetrical projection  36  arrangement for a bulb shield  32  may require that the actuator shaft  44  rotate the bulb shield  32  both clockwise and counterclockwise to change the shielding pattern about the bulb  28 .  
         [0024]    Referring again to FIG. 1, an insulated electrical lead  62  is attached to the electrical interface. The insulated electrical lead  62  carries electricity from the automobile&#39;s electrical system to the lamp  78 . The insulated electrical lead  62  is utilized to transfer electricity to the lamp assembly in the event a high intensity discharge bulb is used.  
         [0025]    A decorative cap  48  is attached to the frame  30 . The decorative cap  48  obscures the upper section of the frame  30  and components located within and/or upon the frame  30  from outside view.  
         [0026]    A headlamp control system (not shown) is in electrical communication with the actuator  42 . The headlamp control system (not shown) may be a microprocessor or another controller, which receives input from various sensors or switches, such as dashboard switches under human operation. The headlamp control system (not shown) controls the duration and rotational direction of actuator shaft  44  rotation by selectively applying an electric current to the electrical leads (not shown) which are connected to the actuator  42 .  
         [0027]    Operation of the disclosed embodiment of the bifunctional headlamp  18  containing a rotating shield with integral actuator is now described with reference to FIG. 1. The headlamp control system determines when electric current is provided to the actuator  42 . The application of an electric current to the actuator  42  causes the actuator  42  to operate on the actuator shaft  44 , rotating the actuator shaft  44  for a specific duration and in a specific rotational direction as communicated by the headlamp control system. In particular, the application of electric current to the actuator  42  causes the actuator shaft  44  to rotate ninety degrees clockwise from a low beam position, and into a high beam position. It should be appreciated that if the bulb shield  32  is symmetrical, and the projections  36  of the bulb shield  32  are opposite one another, a ninety degree rotation either clockwise or counterclockwise will accomplish the same effect. Thus, if the first position of the bulb shield  32  was such that the projections  36  were vertically aligned with respect to the bifunctional headlamp  18 , then a ninety degree rotation of the bulb shield  32  clockwise or counterclockwise would reorient the bulb shield  32  such that the projections  36  were horizontally aligned with respect to the bifunctional headlamp  18 . Of course, if the projections  36  of the bulb shield  32  are arranged asymmetrically, rotation of the bulb shield  32  over an angle other than ninety degrees may be employed to rotate the bulb shield  32  between a high beam position and a low beam position. Also, if the bulb shield projections  36  are arranged asymmetrically about the bulb shield  32 , the actuator  42  may be employed to rotate the bulb shield  32  in both a clockwise and counterclockwise fashion, to rotate the bulb shield  32  between a high beam position and a low beam position..  
         [0028]    Movement of the actuator shaft  44  translates into movement of the shield support  38  and movement of the bulb shield  32 . The bulb shield  32 , as described above, rotates about the bulb  28 . In the low beam position, the projections  36  of the bulb shield  32  are aligned along the sides of the bulb  28  and block light rays that contribute to a high beam pattern from striking the reflector  66 . At the same time, the bulb shield allows light rays that contribute to a low beam pattern to strike the reflector  66  and emit a low beam from the headlamp  18 . In the high beam position, the projections  36  of the bulb shield are aligned along the top and bottom of the bulb and the bulb shield allows light rays that contribute to both the high beam and low beam pattern to strike the reflector  66  and emit a high beam from the headlamp.  
         [0029]    [0029]FIG. 2A is a top cross sectional view of the bifunctional headlamp  18  along the line A-A of FIG. 1, showing the position of the bulb shield allowing light to be projected in a low beam pattern. In FIG. 2A, light rays  100  that contribute to a low beam pattern strike the reflector  66  and are emitted from the bifunctional headlamp  18 . Other light rays, specifically those that contribute to a high beam pattern, are blocked by the projections  36  of the bulb shield  32 . Thus, if the projections  36  aligned horizontally with respect to the bifunctional headlamp  18 , the bulb shield  32  allows only low beam light rays to emit from the bifunctional headlamp  18 .  
         [0030]    [0030]FIG. 2B is a top cross sectional view of the bifunctional headlamp  18  along the line A-A of FIG. 1, showing the position of the bulb shield allowing light to be projected in a high beam pattern. In FIG. 2B, light rays that contribute to both a high beam  102  and a low beam  100  strike the reflector  66  and are emitted from the bifunctional headlamp  18 . In the high beam position, the projections of the bulb shield  32  are positioned above and below the bulb, allowing both the high beam light rays  102  and the low beam light rays  100  to strike the reflector  66  and emit light from the headlamp  18 .  
         [0031]    Referring now to FIG. 5, a front view of the reflector is shown. The decorative cap  48  is shown in FIG. 5 with the reflector  66  positioned in the background. A first portion  58  of the reflector  66  is identified by a plurality of open circles. This first portion  58  is the portion of the reflector used to provide the low beam pattern for the headlamp. A second portion  60  of the reflector  66  is provided adjacent and peripheral to the first portion  58 . The second portion  60  of the reflector  66  is identified by closed circles in FIG. 5. This second portion  60  of the reflector  66  is used in conjunction with the first portion  58  to provide the high beam pattern for the headlamp. When the bulb shield  32  is in the low beam position, the projections  36  of the bulb shield  32  block light from striking the second portion  60  of the reflector, and light is only permitted to strike the first portion  58  of the reflector. When the bulb shield is in the high beam position, light is allowed to strike both the first portion  58  and second portion  60  of the reflector  66 .  
         [0032]    As can be readily seen, the present invention of varying the light pattern of emitted light between a low beam pattern and a high beam pattern creates the ability for one bulb to serve dual purposes. Utilizing the present invention as a headlamp in an automobile serves to decrease the size and weight of the headlamp, by allowing for the reduction in the total number of bulbs and associated components inside the headlamp. In addition, the arrangement provides for significant savings over headlamp arrangements with multiple reflectors and bulbs used to provide high beam and low beam functions.  
         [0033]    Although other advantages may be found and realized and various modifications may be suggested by those versed in the art, it is understood that the present invention is not to be limited to the details given above, but rather may be modified within the scope of the appended claims. For example, the lamp shield position and the reflector orientation, and thus the low beam and high beam patterns, are not limited to positions as described above. The lamp shield and/or the reflector may be positioned such that the low beam and high beam positions remain at right angles, but the entire lamp projection axis may be oriented at an angle or perhaps vertically. Also, the reflector may be able to tilt, thus rendering the reflector independently aimable. In this embodiment, the frame and the components attached therein may tilt with the aimable reflector.