Abstract:
At least one of diagonal cut lines CL1 and CL2, and horizontal cut lines CL3 and CL4 among a spatial distribution pattern PL of luminous intensity for a low beam can be changed.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a head lamp for an automobile which can obtain a spatial distribution pattern of luminous intensity for a low beam (for passing each other) having a diagonal cut line and a horizontal cut line, and more particularly to a head lamp for an automobile which can change at least one of the diagonal cut line and the horizontal cut line, thereby improving a visibility and preventing a forward traveling vehicle, a vehicle traveling in the opposite direction and a pedestrian from being dazzled.  
           [0002]    This kind of head lamp for the automobile is generally provided with a light source bulb and a reflector. When turning on the light source bulb, the light beams emitted from the light source bulb are reflected by the reflector and are irradiated to an external portion in accordance with the spatial distribution pattern of luminous intensity for the low beam having the diagonal cut line and the horizontal cut line.  
           [0003]    However, since the conventional head lamp for the automobile mentioned above is structured such that at least one of the diagonal cut line and the horizontal cut line is fixed, the visibility is constant.  
           [0004]    In this case, as a related art investigated by inventors, Japanese Unexamined Patent Publication No. H11-66908 discloses a head lamp for an automobile in which a shade is made movable so as to switch between a spatial distribution pattern of luminous intensity for a low beam and a spatial distribution pattern of luminous intensity for a high beam (for traveling). However, since the head lamp for the automobile only switches between the spatial distribution pattern of luminous intensity for the low beam and the spatial distribution pattern of luminous intensity for the high beam and at least one of the diagonal cut line and the horizontal cut line of the spatial distribution pattern of luminous intensity for the low beam is fixed, the visibility is constant as in the same manner as the conventional head lamp for the automobile mentioned above.  
         SUMMARY OF THE INVENTION  
         [0005]    An object of the present invention is to provide a head lamp for an automobile which can change at least one of a diagonal cut line and a horizontal cut line, thereby improving a visibility and preventing a forward traveling vehicle, a vehicle traveling in the opposite direction and a pedestrian from being dazzled.  
           [0006]    According to a first aspect of the present invention, in order to achieve the object mentioned above, there is provided a head lamp for an automobile, comprising a movable shade for forming a diagonal cut line, in which the movable shade can move between a first position at which a standard diagonal cut line can be obtained and a second position at which a diagonal cut line having a larger angle of incline than that of the standard diagonal cut line.  
           [0007]    Further, according to another aspect of the present invention, in order to achieve the object mentioned above, there is provided a head lamp for an automobile comprising a movable shade for forming a horizontal cut line, in which the movable shade can move between a first position at which a standard horizontal cut line can be obtained and a second position at which a diagonal cut line obtained by inclining the standard horizontal cut line.  
           [0008]    As a result, since the head lamp for the automobile according to the present invention can change at least one of the diagonal cut line and the horizontal cut line among the spatial distribution pattern of luminous intensity for the low beam, a visibility can be improved and it is possible to prevent a forward traveling vehicle, a vehicle traveling in the opposite direction and a pedestrian from being dazzled. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a front elevational view of a main portion (a reflector) showing a first embodiment of a head lamp for an automobile according to the present invention;  
         [0010]    [0010]FIG. 2 is a cross sectional view along a line II-II in FIG. 1;  
         [0011]    [0011]FIG. 3 is a front elevational schematic view of a spatial distribution pattern of luminous intensity for a low beam according to the first embodiment;  
         [0012]    [0012]FIG. 4 is a plan schematic view of the spatial distribution pattern of luminous intensity for the low beam according to the first embodiment;  
         [0013]    [0013]FIG. 5 is a front elevational view of a main portion (a reflector) showing a second embodiment of a head lamp for an automobile according to the present invention;  
         [0014]    [0014]FIG. 6 is a cross sectional view along a line VI-VI in FIG. 5;  
         [0015]    [0015]FIG. 7 is a front elevational view of a main portion (a reflector) showing a third embodiment of a head lamp for an automobile according to the present invention;  
         [0016]    [0016]FIG. 8 is a front elevational schematic view of a spatial distribution pattern of luminous intensity for a low beam according to the third embodiment; and  
         [0017]    [0017]FIG. 9 is a plan schematic view of the spatial distribution pattern of luminous intensity for the low beam according to the third embodiment. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    In the following description, reference symbol “L” denotes a “left side” in the case of viewing a front portion from a driver side, reference symbol “R” denotes a “right side” in the case of viewing the front portion from the driver side, reference symbol “U” denotes an “upward side” in the case of viewing the front portion from the driver side, and reference symbol “D” denotes a “downward side” in the case of viewing the front portion from the driver side.  
         [0019]    Further, reference symbol “Z-Z” denotes an “optical axis”, reference symbols “HL-HR” and “HR-HL” denote a “horizontal axis” being horizontal with respect to the optical axis Z-Z or a “horizontal axis” of a spatial distribution pattern of luminous intensity, and reference symbol “VU-VD” denotes a “vertical axis” being vertical with respect to the optical axis Z-Z or a “vertical axis” of the spatial distribution pattern of luminous intensity.  
         [0020]    FIGS.  1  to  4  show a first embodiment of a head lamp for an automobile according to the present invention.  
         [0021]    A reflection surface  10  forming a spatial distribution pattern of luminous intensity LP for a low beam shown in FIG. 3 is provided on an inner surface of the reflector  1 . The reflection surface  10 , for example, forms a rotational oval surface. A discharge lamp (a high pressure metal vapor discharge lamp, a high intensity discharge lamp (HID) or the like)  4  serving as a light source bulb is detachably mounted to the reflector  1  via a socket  40 , and a fixed shade  41  is arranged in front of the discharge lamp  4 .  
         [0022]    Further, a movable shade  42  is arranged in the side of the discharge lamp  4 .  
         [0023]    The movable shade  42  is structured such as to form diagonal cut lines CL 1  and CL 2  shown in FIG. 3, and is arranged so that the movable shade  42  can linearly move between a first position (a position shown by a solid line in FIG. 1) at which a diagonal cut line CL 1  (a diagonal cut line shown by a dotted line in FIG. 3) having an incline of about 15 degrees can be obtained and a second position (a position shown by a double dotted chain line in FIG. 1) at which a diagonal cut line CL 2  (a diagonal cut line shown by a solid line in FIG. 3) can be obtained, by means of driving means  2  and  20 .  
         [0024]    The drive means are constituted by a drive motor  2  and a rotational force transmitting mechanism  20  of a rack and pinion type interposed between the drive motor  2  and the movable shade  42 .  
         [0025]    The reflector  1 , the discharge lamp  4 , the fixed shade  41 , the movable shade  42 , the drive motor  2 , the rotational force transmitting mechanism  20  and the like are arranged within a lamp chamber (not shown) defined by a lamp housing and a front lens or a front cover (not shown), whereby the head lamp for the automobile is constructed. The head lamp for the automobile is provided in both right and left sides of a front portion in the automobile. In this case, there is a case that the reflector  1  is attached to the lamp housing via a vertical optical axis adjusting mechanism (not shown) and a lateral optical axis adjusting mechanism (not shown) so that the optical axis thereof can be adjusted in a vertical direction and a lateral direction.  
         [0026]    The head lamp for the automobile according to the present invention in the first embodiment is constituted by the elements mentioned above, and a description will be given of a used embodiment thereof.  
         [0027]    By turning on the discharge lamp  4  when the movable shade  42  is positioned at the first position, there can be obtained a spatial distribution pattern of luminous intensity LP for the low beam having the standard diagonal cut line CL 1  having the incline of about  15  degrees shown by a broken line in FIG. 3 and the horizontal cut line CL 2 .  
         [0028]    In this case, in the case that no forward traveling vehicle exists, the drive motor  2  is driven so as to move the movable shade  42  from the first position to the second position. Then, the diagonal cut line changes to the diagonal cut line CL 2  having the angle of incline larger than the angle of incline  15  degrees of the standard diagonal cut line CL 1 . As a result, as shown by the solid lines in FIGS. 3 and 4, an apart portion in comparison with the spatial distribution pattern of luminous intensity of the standard diagonal cut line CL 1  (shown by the broken line) is lighted, so that a visibility can be improved. For example, as shown in FIG. 3, it is possible to quickly recognize a pedestrian P on the left side shoulder edge of the road.  
         [0029]    Further, in the case that the forward traveling vehicle exists or the pedestrian exists near, the drive motor  2  is driven so as to move the movable shade  42  from the second position to the first position. Then, the diagonal cut line changes to the standard diagonal cut line CL 1  having the angle of incline of about 15 degrees. As a result, it is possible to obtain the spatial distribution pattern of luminous intensity of the standard diagonal cut line CL 1  shown by the broken lines in FIGS. 3 and 4, so that no dazzling is applied to the forward traveling vehicle and the pedestrian existing near.  
         [0030]    [0030]FIGS. 5 and 6 show a second embodiment of a head lamp for an automobile according to the present invention. In the drawings, the same reference numerals as those in FIGS.  1  to  4  denote the same elements.  
         [0031]    The head lamp according to the second embodiment is structured such that the movable shade  42  is rotated and moved between a first position (a position shown by a solid line in FIG. 5) at which a standard diagonal cut line CL 1  having an incline of about 15 degrees can be obtained and a second position (a position shown by a double dotted chain line in FIG. 5) at which a diagonal cut line CL 2  having an angle of incline larger than that of the standard diagonal cut line CL 1 , by means of the drive motor  2  and a rotational force transmitting mechanism  21 .  
         [0032]    The structure according to the second embodiment can achieve the same operation and effect as those of the first embodiment mentioned above.  
         [0033]    In particular, in the structure according to the second embodiment, since the movable shade  42  rotates between the first position and the second position, the movable shade  42  positioned at the second position comes near the discharge lamp  4 , so that an accuracy of the diagonal cut line CL 2  can be improved. Further, when the movable shade  42  comes near the discharge lamp  4 , a density of the light beams is increased at that degree, so that a shading effect can be increased. Further, since the movable shade  42  rotates at a little amount, the driving means  2  and  21  can be made compact so as to be reduced a cost, and a driving accuracy can be improved, so that accurate diagonal cut lines CL 1  and CL 2  can be obtained.  
         [0034]    FIGS.  7  to  9  show a third embodiment of a head lamp for an automobile according to the present invention. In the drawings, the same reference numerals as those of FIGS.  1  to  6  denote the same elements.  
         [0035]    In the structure according to the third embodiment, the movable shade  42  and the driving means  2  and  21  according to the first and second embodiments mentioned above are replaced by a first movable shade and first driving means, and a second movable shade  43  is arranged in such a manner as to move to a side portion of the discharge lamp  4  by second driving means  22  and  23  together with the first movable shade  42  and the first driving means  2  and  21 .  
         [0036]    That is, the second movable shade  43  is structured such as to form a horizontal cut line CL 3  and a diagonal cut line CL 4  shown in FIG. 8, and is arranged so as to be rotatable and movable between a first position (a position shown by a solid line in FIG. 7) at which a second position (a horizontal cut line shown by a dotted line in FIG. 7) at which the standard horizontal cut line CL 3  (a cut line shown by a solid line in FIG. 8) can be obtained can be obtained and the diagonal cut line CL 4  (a position shown by a double dotted chain line in FIG. 8) inclined with respect to the standard horizontal cut line CL 3 , by the second driving means  22  and  23  which are the same as the first driving means  2  and  20 .  
         [0037]    The structure according to the third embodiment can achieve the same operation and effect as those of the first and second embodiments mentioned above.  
         [0038]    In particular, since the structure according to the third embodiment is provided with the second movable shade  43 , the standard horizontal cut line CL 3  shown by the broken line in FIG. 8 can be obtained when the second movable shade  43  is positioned at the first position. Further, in the case that no vehicle traveling in the opposite direction exists, when the second drive motor  22  is driven so as to move the second movable shade  43  from the first position to the second position, a right diagonal cut line CL 4  and a right spatial distribution pattern of luminous intensity PR shown by solid lines in FIGS. 8 and 9 can be obtained, so that a visibility can be improved. For example, it is possible to quickly recognize the vehicle traveling in the opposite direction (not shown).  
         [0039]    Further, in the case that the vehicle traveling in the opposite direction exists, when the second motor  22  is driven so as to move the second movable shade  43  from the second position to the first position, the cut line is changed from the diagonal cut line CL 4  to the horizontal cut line CL 3 , so that no dazzling is applied to the vehicle traveling in the opposite direction.  
         [0040]    In the third embodiment, the structure may be made such that the first movable shade  42  is omitted and only the second movable shade  43  is used.  
         [0041]    In this case, in the embodiments mentioned above, the description is given of the head lamp for the automobile traveling on the road for keeping to the left, however, in the case of a head lamp for an automobile traveling on the road for keeping the right, a structure, a spatial distribution pattern of luminous intensity and the like are laterally reversed.  
         [0042]    Further, the spatial distribution pattern of the luminous intensity LP for the low beam mentioned above can be controlled only by the reflection surface  10 , or the reflection surface and the front lens, or only by the front lens.  
         [0043]    Further, as the light source bulb, for example, a light source bulb having a single filament can be employed, in addition to the discharge lamp  4  mentioned above.