Patent Publication Number: US-6709139-B2

Title: Projection-type vehicular headlamp having reduced dazzling effect

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to vehicular headlamps. More specifically, the present invention relates to a projection-type vehicular headlamp in which dazzling of the vision of oncoming drivers by light directly emitted from the light source of the lamp is prevented. 
     In a vehicular headlamp of the projection type, a cut-line forming shade is arranged such that its upper edge is located close to a focal point of a reflector that reflects and condenses light emitted from a light source. The reflected light, some portion of which is cut off by the cut-line forming shade, is projected forwards by a condenser lens. Such a headlamp requires provisions for providing convection of air to protect the reflector from heat, and also it is desired to reduce the weight of the projection unit composed of the light source, reflector, cut-line forming shade, and condenser lens. For these purposes, a recess can be formed in a lens holder used to mount the condenser lens to the reflector, or the lens holder itself can be formed with a ring-like lens holding portion having a plurality of arms and connected to the reflector via the arms. In this arrangement, an opening is formed between the reflector and the condenser lens. 
     However, if the opening is formed between the reflector and the condenser lens as described above, some of the light directly emitted from the light source passes through the opening. Such light is radiated to the outside without impinging on the condenser lens, resulting in dazzle to the vision of drivers of oncoming vehicles or pedestrians. 
     If the reflector has an elliptical lower surface, light from the light source bulb emitted toward the lower surface of the reflector is reflected by the reflector and radiated to the outside through the opening between the condenser lens and the reflector. This too can cause a problem of dazzlement. 
     To solve this problem, an extension can provided which covers the periphery of the projector unit, thus cutting off direct light traveling through the opening. If the extension for covering the periphery of the projector unit is used to prevent dazzlement due to direct beams of light as in the case of the aforementioned vehicular headlamp, it is of course impossible to dispense with the extension. Moreover, the direct light is cut off in regions where it is diffused to some extent. As a result, the necessity of enlarging the extension emerges as another problem. 
     It is thus an object of the present invention to prevent dazzlement from being caused by beams of light directly emitted from a light source without requiring any bulky component members. 
     SUMMARY OF THE INVENTION 
     A vehicular headlamp according to the present invention is intended to solve the problems mentioned above. For this purpose, a vehicular headlamp of the invention comprises a light source, a reflector, a cut-line forming shade for forming a cut line, and a condenser lens. The cut-line forming shade cuts off some of the light emitted from the light source and reflected by the reflector and forms shaped beams of light. The condenser lens projects the shaped beams of light forwards and radiates them according to a predetermined light distribution pattern. An opening is formed between the condenser lens and the reflector. A dazzling-light cutting shade for cutting off light emitted toward regions above the light distribution pattern is disposed between the light source and the opening. 
     Thus, the vehicular headlamp according to the present invention prevent dazzlement from occurring due to light directly emitted from the light source. Also, since the dazzling-light cutting shade is disposed between the light source and the opening, direct beams of light are cut off in regions where they are diffused just slightly. Therefore, no bulky component members are required. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal sectional view of a vehicular headlamp constructed according to a preferred embodiment of the present invention. 
     FIG. 2 is a cross-sectional view taken along a line II—II in FIG.  1 . 
     FIG. 3 is a perspective view of a cut-line forming shade and a dazzling-light cutting shade used in the embodiment of FIGS.  1  and  2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A vehicular headlamp constructed according to a preferred embodiment of the present invention will be described hereinafter with reference to the accompanying drawings. 
     A vehicular headlamp  1  is composed of a lamp body  2 , a cover lens  3 , and a projector unit  5 . The cover lens  3  covers a front opening of the lamp body  2 . The projector unit  5  is tiltably disposed in a lighting fixture chamber  4  defined by the lamp body  2  and the cover lens  3 . 
     The projector unit  5  includes a reflector  6 , a light source bulb  7 , a condenser lens  8 , and a cut-line forming shade  9 . The reflector  6  supports the light source bulb  7 . 
     The reflector  6  has a main reflecting surface  6   a  for condensing light emitted from the light source bulb  7  at a predetermined focus area. The reflector  6  is tiltably supported with respect to the lamp body  2  by means of a known support mechanism such as a tilt support mechanism, which is composed of a rotatable fulcrum portion and a distance adjustment portion. The rotatable fulcrum portion is constructed of a ball joint. The distance adjustment portion is composed of an adjusting screw rotatably supported by the lamp body  2  and a nut member supported by the reflector  6  and into which the adjusting screw is threadedly joined. 
     The condenser lens  8 , which is a convex lens, is supported via a lens holder  10  at a location in front of the reflector  6 . 
     The lens holder  10  is constructed by integrally forming a lens supporting portion  11  having a generally annular shape and stays  12  protruding rearwards from the lens supporting portion  11  (see FIG.  2 ). By “integrally forming” is meant that the two members are formed from a single body of material. The lens supporting portion  11  supports a peripheral edge portion of the condenser lens  8 . The stays  12  are fixed at their rear ends to an opening end of the reflector  6 . 
     The lens holder  10  supports a shade supporting body  13 . The shade supporting body  13  has a supported portion  14  having an annular shape and which is substantially equal in size to the lens supporting portion  11  of the lens holder  10 . Mounted strips  14   a  formed in right and left lateral portions of the supported portion  14  are fixed by means of screws to mounting boss portions  11   a  which protrude from rear surfaces of right and left lateral portions of the lens supporting portion  11  (see FIG.  2 ). 
     The cut-line forming shade  9  and a dazzling-light cutting shade  15  are formed integrally with the shade supporting body  13  (see FIGS.  1  and  3 ). The cut-line forming shade  9  rises substantially vertically and is formed as a plate having a curved surface that is concave toward the front in horizontal cross section. The cut-line forming shade  9  is integrated at its opposed ends with the supported portion  14  of the shade supporting body  13  continuously. The upper edge  9   a  of the cut-line forming shade  9  is located contiguous to the optical axis of the reflector  6  in the vicinity of the focal point thereof. 
     The dazzling-light cutting shade  15  is constructed by integrally forming a main portion  16  and a rearward extending portion  17 . The main portion  16 , which extends substantially vertically, and is in the form of a plate having a curved surface that is curved in a horizontal cross section in the same manner as the cut-line forming shade  9  (see FIG.  2 ). The rearward extending portion  17  extends rearwards from the upper end of the main portion  16  substantially horizontally (see FIG.  1 ). The main portion  16  is integrated at its opposed ends with the supported portion  14  of the shade supporting body  13 . In a region above the optical axis of the reflector  6 , the lower edge  16   a  of the main portion  16  of the dazzling-light cutting shade  15  is located substantially at the same position as the upper edge  9   a  of the cut-line forming shade  9  in the direction of the optical axis (which extends substantially in the longitudinal direction of a vehicle on which the headlamp is mounted). The rearward extending portion  17  is so located as to cover the space between the main portion  16  and the front end of the upper edge of the reflector  6 . 
     A horizontal reflecting surface  6   b  extending substantially horizontally and an inclined reflecting surface  6   c  extending continuously from the front end of the horizontal reflecting surface  6   b  and inclined forwards and downwards are formed as lower surfaces of the reflector  6  (see FIG.  1 ). All the light directly radiated from the light bulb  7  onto the horizontal reflecting surface  6   b  is reflected by the horizontal reflecting surface  6   b , striking the rear surface of the dazzling-light cutting shade  15 . All the light directly radiated from the light source  7  onto the inclined reflecting surface  6   c  is reflected by the inclined reflecting surface  6   c  and strikes the back surface of the cut-line forming shade  9 . Thus, the dazzling-light cutting shade  15  cuts off all the light traveling from the light source bulb  7  toward the horizontal reflecting surface  6   b , and the cut-line forming shade  9  cuts off all the light traveling from the light source bulb  7  toward the inclined reflecting surface  6   c . As a result, no light is radiated to the outside from the space between the reflector  6  and the condenser lens  8 . 
     All the beams of light radiated directly upwards from the light source bulb  7  and traveling toward the opening between the front end of the reflector  6  and the condenser lens  8  impinge on the dazzling-light cutting shade  15  and are cut off. Thus, there is no that some of the light traveling upwards from the light source bulb  7  will dazzle drivers of oncoming vehicles or pedestrians. 
     It is preferable that the rear surface of the dazzling-light cutting shade  15  be subjected to non-reflective processing such as by application of a non-reflecting coating so as to prevent light from being reflected by the dazzling-light cutting shade  15 . However, even if some light is reflected by the rear surface of the dazzling-light cutting shade  15 , such light is diffused laterally uniformly because of the curvature of the dazzling-light cutting shade  15 . Even if the light thus diffused is reflected again by the reflector, it will not cause dazzlement. 
     As described above, the vehicular headlamp  1  cuts off of light that can dazzle drivers of oncoming vehicles or pedestrians by means of the dazzling-light cutting shade  15  and the cut-line forming shade  9 , prevent such light from being radiated to outside. In addition, the vehicular headlamp  1  does not require any bulky component members such as the extension of the conventional lamp. 
     Further, since the dazzling-light cutting shade  15  is disposed close to the cut-line forming shade  9 , light is cut off in a region where it is focused to some extent. Therefore, there is no need to increase the size of the vehicular headlamp  1 . 
     Furthermore, by forming the dazzling-light cutting shade  15  is integrally with the cut-line forming shade  9  as described above, it becomes possible to define a positional relation between the dazzling-light cutting shade  15  and the cut-line forming shade  9  precisely. Also, the vehicular headlamp  1  can be mounted easily. 
     According to the foregoing description of the invention, the single vehicular headlamp  1  has the horizontal reflecting surface  6   b  and the inclined reflecting surface  6   c . However, the objects of the present invention can be achieved even without these reflecting surfaces, and aforementioned additional effects can be achieved by either or both of the two reflecting surfaces mentioned above. 
     It is to be noted herein that the shapes and structures of all the component members in the aforementioned embodiment are to be regarded merely as examples obtained in embodying the present invention and that the technical scope of the present invention is not to be construed narrowly on grounds of those shapes and structures. 
     As is apparent from the foregoing description, the vehicular headlamp according to the present invention comprises the light source, the reflector, the cut-line forming shade for forming a cut line, and the condenser lens. The cut-line forming shade cuts off some beams of light emitted from the light source and reflected by the reflector and forms shaped beams of light. The condenser lens projects the shaped beams of light forwards and radiates them according to a light distribution pattern. The opening is formed between the condenser lens and the reflector. The dazzling-light cutting shade for cutting off beams of light emitted toward the region above the light distribution pattern is disposed between the light source and the opening. 
     Thus, the vehicular headlamp according to the present invention can prevent dazzlement of the vision of the drivers or pedestrians from occurring due to light directly emitted from the light source. Also, since the dazzling-light cutting shade is disposed between the light source and the opening, direct beams of light can be cut off in a region where they are diffused just slightly. Therefore, no bulky component member is required. 
     The dazzling-light cutting shade may have a portion extending rearwards substantially horizontally. Thus, the portion extending downward substantially vertically can be positioned precisely by adjusting the length of the portion extending rearwards substantially horizontally. 
     In the preferred embodiment, the dazzling-light cutting shade and the cut-line forming shade are located at the same position when viewed in the longitudinal direction of the vehicle. Thus, the dazzling-light cutting shade can cut off only direct light that could otherwise cause dazzlement, without cutting off light reflected by the reflector which is intended to be used for illumination. 
     Moreover, the dazzling-light cutting shade may be curved in horizontal cross-sectional shape. Thus, even if light directly emitted from the light source is reflected by the rear surface of the dazzling-light cutting shade and then by the reflector, such light is laterally diffused by the rear surface of the dazzling-light cutting shade, which is designed as a curved surface. As a result, there is no likelihood of dazzlement. 
     The dazzling-light cutting shade and the cut-line forming shade may be formed integrally. Thus, a positional relation between the two shades can be determined precisely. 
     The reflecting surface for reflecting beams of light emitted from the light source toward the rear of the dazzling-light cutting shade is formed in the lower portion of the reflector. Thus, it is possible to cut off light reflected by the lower portion of the reflector which cannot be used effectively for the purpose of illumination because of the possibility of dazzlement. 
     The reflecting surface for reflecting light emitted from the light source toward the rear of the cut-line forming shade is formed in the lower portion of the reflector. Thus, it is possible to cut off light reflected by lower portion of the reflector which cannot be used effectively for the purpose of illumination because of the threat of dazzlement. 
     It should further be apparent to those skilled in the art that various changes in form and detail of the invention as shown and described above may be made. It is intended that such changes be included within the spirit and scope of the claims appended hereto.