Patent Publication Number: US-2003235056-A1

Title: High/low switching mechanism of vehicle headlight

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates generally to a vehicle headlight, and in particular to a mechanism for switching between high beam and low beam of the vehicle headlight.  
       BACKGROUND OF THE INVENTION  
       [0002] Vehicles or automobiles are provided with headlight for driving in dark environments. The headlight comprises one or more light sources, such as bulbs, generating light beams and a reflector that reflects and selectively projects the light beams in different angles, which are commonly referred to as “high beam” and “low beam”. A conventional headlight comprises a bulb inside which two sets of lighting filaments are arranged. One of the filaments is shielded while another filament is not. The light generated by the unshielded filament is not constrained and allowed to orient to a high and thus far location and is thus called “high beam” while the light generated by the shielded filament is constrained to a low and thus near location and is thus called “low beam”.  
       [0003] Some of the vehicle headlights available in the market comprise a high intensity discharge (HID) lamp for providing high luminous intensity. The HID lamp comprises a hermetic chamber inside which ions are filled. The ions discharge and generate light when a sufficient electric field is applied to the lamp. Since the light of a HID lamp is generated by electrical discharge, each HID lamp has a single light source. Thus, a vehicle headlight must be comprised of two HID lamps in order to selectively generate high beam and low beam. This apparently increases the overall costs of the headlight.  
       [0004] A headlight comprising a bulb movable with respect to a reflector for changing relative position therebetween is also available. By changing the relative position between the bulb and the reflector, the light beam of the bulb is projected in different angles and thus switched between “high beam” and “low beam”. Since the relative position of the bulb with respect to the reflector is not fixed, the bulb cannot be properly positioned in a focal point of the reflector all the time and the light beam cannot be properly focused. This may lead to incorrect perception of other drivers with respect to the distance between the vehicle issuing the non-properly focused light and their cars and thus causing traffic accidents.  
       [0005] It is thus desired to have a mechanism for switching high beam and low beam of a vehicle headlight for overcoming the above problems.  
       SUMMARY OF THE INVENTION  
       [0006] An object of the present invention is to provide a mechanism for switching high beam and low beam of a vehicle headlight by selectively moving shielding members to partially shield a single and properly positioned light source of the headlight.  
       [0007] Another object of the present invention is to provide a mechanism for switching high beam and low beam of a vehicle headlight without moving a light source of the headlight with respect to a reflector thereby simplifying the overall structure of the headlight and reducing the costs thereof.  
       [0008] To achieve the above object, in accordance with the present invention, there is provided a mechanism for switching high beam and low beam of a vehicle headlight, comprising a base fixed inside the vehicle headlight and retaining the light bulb. A frame is mounted to the base. Two shielding members are pivotally mounted to the frame on opposite sides of the bulb. A control plate is pivoted to the base and driven by a solenoid between active and inactive positions. A link bar has an end attached to the control plate and an opposite end pivoted to the shielding members whereby when the control plate is driven to the active position by the solenoid, the shielding members are rotated, by being driven by the pivotal connection between the link bar and the shielding members, to a position where the shielding members partially shield the light bulb and block a portion of light generated by the light bulb incident upon the reflector thereby realizing the low beam of the vehicle headlight, and when the control plate is moved to the inactive position by the solenoid, the shielding members are rotated away from the light bulb and no longer block the light generated by the light bulb thereby realizing the high beam of the vehicle headlight. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009] The present invention will be apparent to those skilled in the art by reading the following description of a preferred embodiment thereof, with reference to the attached drawings, in which:  
     [0010]FIG. 1 is a perspective view of a vehicle headlight in which a switching mechanism in accordance with the present invention is embodied;  
     [0011]FIG. 2 is an exploded view of the vehicle headlight incorporating the switching mechanism of the present invention;  
     [0012]FIG. 3 is a side elevational view showing the switching mechanism at an active position;  
     [0013]FIG. 4 is similar to FIG. 3 but showing the switching mechanism at an inactive position;  
     [0014]FIG. 5 is a top plan view showing the switching mechanism at the active position; and  
     [0015]FIG. 6 is similar to FIG. 5 but showing the switching mechanism at the inactive position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0016] With reference to the drawings and in particular to FIGS. 1 and 2, a vehicle headlight comprises a holder or a base  1  fixed inside a concave reflector  8  (see phantom lines of FIGS. 5 and 6) of the headlight. An illuminator  2 , such as a high intensity discharge (HID) bulb, is attached to the holder  1  for being positioned in the focal point of the concave reflector  8 . The illuminator  2  generates a light beam that is reflected and projected by the concave reflector  8 . A switching mechanism constructed in accordance with the present invention is incorporated in the headlight for selectively and partially blocking the light generated by the illuminator  2  thereby switching angular orientation of the light beam projected by the reflector  8 .  
     [0017] The holder  1  defines a central bore  14  in which the illuminator  2  is received and fixed. The illuminator  2  comprises a base member  21  on which a bulb  22 , such as a HID bulb, is fixed. The base member  21  is attached to an underside of the holder  1  by any known manner with the bulb  22  extending through the bore  14 .  
     [0018] The holder  1  has a raised portion (not labeled) partially surrounding the central bore  14  and having a top face (not labeled) in which slits  13  are defined. A frame  5  defining a chamber  52  has legs  51  received in slits  13  and fixed to the raised portion of the holder  1  with the bulb  22  partially accommodated in the chamber  52 .  
     [0019] Two opposite projections  11  are formed on the holder  1  and each forms a pivot  111  extending in opposite directions. A control plate  4 , substantially U-shaped, has two opposite side segments connected by a central segment (both not labeled). Two opposite lugs (not labeled) corresponding to the projections  11  of the holder  1  are respectively formed on the side segments of the control plate  4  and each defines a hole  41  rotatably receiving the corresponding pivot  111  thereby pivotally attaching the control plate  4  to the holder  1 .  
     [0020] A biasing element  3  is mounted between the holder  1  and each side segment of the control plate  4  to bias the control plate  4  to an active position, as shown in FIGS. 3 and 5, which will be further discussed. In the embodiment illustrated, the biasing element  3  comprises a leaf spring having an end  31  received and fixed in a slit  15  defined in the holder  1  and an opposite end  32  engaging an underside of the corresponding side segment of the control plate  4  for biasing the control plate  4 .  
     [0021] Two holes  12  are defined in the raised portion of the holder  1 , each movably receiving a stem  44  which is driven by a driving unit (not shown) arranged inside the holder  1  to move along the hole  12 . Each stem  44  has a neck  442  and forms an expanded free end  441 . The neck  442  of the stem  44  is received in a slot  42  defined in each side segment of the control plate  4  and fixed together by the expanded end  441  engaging the side segment of the control plate  4 . In the embodiment illustrated, the slot  42  is made L-shaped having a major section (not labeled) retaining the neck  442  of the stem  44  and a minor section (not labeled) forming an opening toward a side edge of the side segment for entry of the neck  442  of the stem  44  into the slot  42 . The major section of the slot  42  is dimensioned to allow a limited relative movement between the neck  442  of the stem  44  and the control plate  4 . The L-shaped configuration of the slot  42  prevents the stem  44  from detaching from the control plate  4 . When the stems  44  are driven by the driving unit into the holes  12 , the control plate  4  is moved by the stems  44 , against the biasing elements  3 , from the active position showing FIGS. 3 and 5 toward an inactive position as shown in FIGS. 4 and 6.  
     [0022] Two shielding members  7  are pivotally mounted to the frame  5  on opposite sides of the bulb  22  by means of pivot shafts  73  extending through aligned holes  53 ,  71  defined in the frame  5  and the shielding members  7  whereby the shielding members  7  are rotatable with respect to the bulb  22 . A link bar  6  has a first end coupled to the control plate  4  and an opposite second end forming two lugs  61  corresponding to the shielding members  7 . Each lug  61  forms a slot  611 . A connection shaft  731  extends through the slot  611  of each lug  61  of the link bar  6  and a hole  72  defined in the corresponding shielding member  7  whereby when the link bar  6  is moved by the rotation of the control plate  4  about the pivots  111 , the shielding members  7  are driven by the connection shafts  731  to rotate about the pivot shafts  73  between an active position shown in FIGS. 3 and 5 and an inactive position shown in FIGS. 4 and 6.  
     [0023] In the embodiment illustrated, the connection shaft  731  is attached to the pivot shaft  73  by a cross bar (not labeled) whereby the connection shaft  731  and the pivot shaft  73  form a unitary, J-shaped member. However, it is apparent to those having ordinary skills to provide separate pivot shaft  73  and connection shaft  731  for achieving the same functions.  
     [0024] The first end of the link bar  6  forms two opposite slits  62  on opposite edges thereof. The central segment of the control plate  4  defines a notch  43  sized to receive the first end of the link bar  6  therein with opposite edges of the notch  43  received in and engaging the slits  62  of the link bar  6  to couple the link bar  6  to the control plate  4 . The raised portion of the holder  1  may form a passageway  16  for accommodating and guiding the movement of the link bar  6 .  
     [0025] Referring to FIGS.  3 - 6 , when the driving unit is not actuated and the control plate  4  is biased by the biasing elements  3  to the active position as shown in FIGS. 3 and 5, the shielding members  7  that have an extension having an L-shaped cross section, partially cover and shield the bulb  22  on opposite sides and top side (FIG. 5) thereof, whereby the light from the bulb  22  is partially blocked from being incident upon an upper portion of the reflector  8 . The light beam projected by the reflector  8  is thus directed toward a low angle and realizing a low beam.  
     [0026] By actuating the driving unit, the control plate  4  is moved by means of the stems  44  to the inactive position as shown in FIGS. 4 and 6. The shielding members  7  are moved away from and thus completely exposing the bulb  22  toward the reflector  8  (FIG. 6). The light generated by the bulb  22  is completely incident upon the reflector  22 , which in turn projects the light with a high angle and thus realizing a high beam.  
     [0027] The driving unit that drives the stems  44  and thus the control plate  4  can be of any known structure. For example, an electrically-excited magnetic force generation device, such as a solenoid, can be employed to attract and move the stems  44  that are made of ferromagnetic materials. Alternatively, a mechanical coupling can be employed to couple the stems  44  to the driving unit. The structure of the driving unit is beyond the scope of the present invention and will not be further discussed herein.  
     [0028] Although the present invention has been described with reference to the preferred embodiment thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.