Patent Publication Number: US-2010118559-A1

Title: Vehicular lamp unit and vehicular lamp

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention relates to a vehicular lamp unit and a vehicular lamp of so-called projector-type, and, more particularly, relates to a vehicular lamp unit and a vehicular lamp provided with an additional reflector that forms a cut-off line of a light distribution pattern. 
     2. Related Art 
     Conventionally, as one form of a vehicular lamp, such as a headlamp, a so-called projector-type vehicular lamp is known. This projector-type vehicular lamp is structured to collect and reflect light from a light source disposed on an optical axis to the front towards the optical axis using a reflector, and to radiate the reflected light to the front of the lamp via a projection lens provided in front of the reflector. 
     The conventional projector-type vehicular lamp uses, as the light source, a discharging light source of a discharge bulb, a filament of a halogen bulb, or the like. However, because the light source has a certain size as a line segment light source, the reflector also has to have a certain size. Thus, it is difficult to realize a large reduction in overall size of the lamp unit. 
     Accordingly, there has been proposed a vehicular lamp in which an LED (light-emitting diode), which is a small-sized light source, is used. However, there has been a problem that, in a lamp which uses an LED as a light source, it is hard to obtain a light distribution pattern with sufficient luminous intensity as compared to a lamp that uses the same number of discharge bulbs, halogen bulbs, or the like as the number of the LEDs used. 
     A headlamp unit (lamp unit) described in Patent Document 1 is an example of a lamp unit designed to solve the problem above. The headlamp unit is structured such that a second reflective surface (upper surface) is formed on a sub-reflector provided to form a light distribution pattern having a cut-off line by blocking a part of reflected light from a first reflective surface of a main reflector. Also, a part of the reflected light from the main reflector is reflected to a convex lens (projection lens). Therefore, the light that is blocked by the sub-reflector, and thus not used, can be effectively utilized for beam radiation. Accordingly, the headlamp is designed such that the usable luminous flux of the lamp, which uses an LED as the light source, is increased, and a light distribution pattern with sufficient luminous intensity can be obtained. 
     [Patent Document 1] Japanese Patent Application Laid-Open (Kokai) No. JP-A-2006-107955 
     SUMMARY OF INVENTION 
     However, the second reflective surface of the sub-reflector in the headlamp unit of the aforementioned Patent Document 1 is formed with a center step portion formed along an optical axis of the convex lens. Further, a high-position reflective surface and a low-position reflective surface are formed on both sides of the center step portion. 
     Therefore, reflected light reflected by the second reflective surface does not uniformly appear on a light distribution pattern formed by the reflected light from the first reflective surface of the main reflector, and a luminescent unevenness is likely to occur. Specifically, reflected light reflected by an inclined surface of the center step portion, which inclines in a lateral direction, appears from a hot zone of the light distribution pattern to an obliquely downward direction, so that the light distribution pattern sometimes gives an uncomfortable feeling to a driver. 
     Accordingly, one or more embodiments of the present invention provide a vehicular lamp unit and a vehicular lamp capable of reducing a luminescent unevenness when a part of reflected light from a reflector is reflected by an upper surface of an additional reflector so as to increase a total amount of light. 
     One or more embodiments of the present invention relate to a vehicular lamp unit comprising: a projection lens disposed on an optical axis extending in a vehicular longitudinal direction; a light source disposed rearward of a rear side focal point of the projection lens; a reflector reflecting direct light from the light source to the front towards the optical axis; an additional reflector disposed between the projection lens and the light source, the additional reflector comprising a flat upper surface extending rearward along the optical axis from a front end edge positioned in the vicinity of the rear side focal point of the projection lens that reflects a part of the reflected light from the reflector towards the projection lens; and a shade portion disposed on the front end edge of the upper surface of the additional reflector, wherein the shade portion forms a cut-off line of a light distribution pattern by blocking a part of the reflected light from the reflector and a part of the direct light from the light source. 
     According to the vehicular lamp unit structured as described above, the shade portion forming the cut-off line of the light distribution pattern is disposed on the front end edge of the upper surface of the additional reflector. Further, the upper surface of the additional reflector, except the vicinity of the front end edge, is formed as a horizontal flat surface extending rearward along the optical axis. 
     As a result of this, almost all of the reflected light reflected by the upper surface of the additional reflector corresponds to light reflected by a simple horizontal surface, so that it is possible to reduce a luminescent unevenness of the light distribution pattern by reducing the light reflected by an inclined surface of the shade portion that inclines in a lateral direction. 
     Note that, in the vehicular lamp unit structured as described above, it is preferable that the shade portion have a protrusion portion formed by protruding a part of the upper surface of the additional reflector, which is formed as a horizontal surface including the optical axis, along the front end edge. 
     With the use of the vehicular lamp unit having such a structure, the light reflected by the upper surface of the additional reflector, which is formed as a horizontal surface including the optical axis, is emitted via a portion towards a center of the projection lens. Thus, the light is likely to converge in the vicinity of the cut-off line on the light distribution pattern. Accordingly, it is possible to improve a distance visibility by making a hot zone of the light distribution pattern provided by the additional reflector appear in the vicinity of the cut-off line. 
     Further, one or more embodiments of the present invention relate to a vehicular lamp characterized in that an entire light distribution pattern is formed by combining a light distribution from the vehicular lamp unit structured as described above and a light distribution from another vehicular lamp unit having a light collecting power lower than a light collecting power of the above vehicular lamp unit. 
     With the use of the vehicular lamp structured as above, when light distributions from a plurality of lamp units are combined to form an entire light distribution pattern, by forming the upper surface of the additional reflector in the light collecting-type lamp unit having a light collecting power higher than that of another vehicular lamp unit as a horizontal surface including the optical axis, it is possible to improve the distance visibility by making the hot zone appear in the vicinity of the cut-off line. 
     According to the vehicular lamp unit according to one or more embodiments of the present invention, the upper surface of the additional reflector, except the front end edge, is formed as a horizontal flat surface extending rearward along the optical axis, and almost all of the reflected light reflected by the upper surface of the additional reflector corresponds to the light reflected by a simple horizontal surface. 
     Therefore, by reducing the light reflected by the inclined surface of the shade portion, which inclines in a lateral direction, to reduce the luminescent unevenness of the light distribution pattern, it is possible to reduce an uncomfortable feeling given to a driver by the light distribution pattern. 
     Other aspects and advantages of the invention will be apparent from the following description, the drawings and the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a horizontal cross-sectional view of a vehicular lamp according to one or more embodiments of the present invention. 
         FIG. 2  is a sectional view along the line II-II in  FIG. 1 . 
         FIG. 3  is a longitudinal sectional view that explains a basic structure of a lamp unit shown in  FIG. 2 . 
         FIG. 4  is an enlarged sectional view of a substantial part of the lamp unit shown in  FIG. 3 . 
         FIG. 5  is an upper perspective view of an additional reflector shown in  FIG. 2 . 
         FIG. 6  is a view that shows, in a perspective manner, a low-beam light distribution pattern formed on a virtual vertical screen disposed at a position 25 meters (m) ahead of the lamp by light radiated from the lamp unit shown in  FIG. 2 . 
         FIG. 7  is an upper perspective view of an additional reflector showing a modified example of the additional reflector shown in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     Hereafter, embodiments of a vehicular lamp unit and a vehicular lamp according to the present invention will be described in detail with reference to accompanying drawings. 
       FIG. 1  is a horizontal cross-sectional view of a vehicular lamp according to one or more embodiments of the present invention. 
     A vehicular lamp  100  is a low-beam headlamp, and is structured such that, in a lamp chamber formed of a plain translucent cover  11  and a lamp body  13 , a plurality of (two, in the embodiment shown) lamp units are housed side-by-side. The lamp units are formed of a lamp unit (vehicular lamp unit)  40  having a high light collecting power and another lamp unit (another vehicular lamp unit)  20  having a light collecting power lower than that of the lamp unit  40 . 
     These lamp units  20 ,  40  are supported in the lamp body  13  via a frame (not shown), and the frame is supported in the lamp body  13  via an aiming mechanism (not shown). 
     The aiming mechanism is a mechanism for finely adjusting attachment positions and attachment angles of these lamp units  20 ,  40 . When the aiming adjustment is completed, a lens central axis Ax of each of the lamp units  20 ,  40  extends in a downward direction by about 0.5 to 0.6 degrees relative to a vehicular longitudinal direction. 
     As will be described later, the lamp unit  20  forms a diffusion zone formation pattern WZ having horizontal and oblique cut-off lines on an upper end edge thereof. The lamp unit  40  forms a hot zone formation pattern HZ having horizontal and oblique cut-off lines on an upper end edge thereof. 
     Specifically, a low-beam light distribution pattern PL formed by the vehicular lamp  100  is designed to be formed as a combined light distribution pattern of the diffusion zone formation pattern WZ and the hot zone formation pattern HZ formed by these two lamp units  20 ,  40  (refer to  FIG. 6 ). 
     These lamp units  20 ,  40 , which serve as low-beam light distribution pattern forming units, are structured as projector-type lamp units each formed of a light source and a projection lens provided on a front side of the light source, as will be described later. 
     Hereinafter, a concrete structure of each of the lamp units  20 ,  40  will be described. 
     First, a structure of the lamp unit  40  will be described. 
       FIG. 2  is a sectional view along the line II-II in  FIG. 1 ,  FIG. 3  is a longitudinal sectional view that explains a basic structure of a lamp unit shown in  FIG. 2 ,  FIG. 4  is an enlarged sectional view of a substantial part of the lamp unit shown in  FIG. 3 ,  FIG. 5  is an upper perspective view of an additional reflector shown in  FIG. 2 , and  FIG. 6  is a view that shows, in a perspective manner, a low-beam light distribution pattern formed on a virtual vertical screen disposed at a position 25 meters (m) ahead of the lamp by light radiated from the lamp unit shown in  FIG. 2 . 
     As shown in  FIG. 2 , the lamp unit  40  includes: a projection lens  45  disposed on an optical axis Ax extending in a vehicular longitudinal direction; an LED (light-emitting diode)  25 , which is used as a light source, disposed rearward of a rear side focal point F of the projection lens  45 ; a reflector  47  that reflects direct light from the LED  25  to the front towards the optical axis Ax; an additional reflector  49  disposed between the projection lens  45  and the LED  25 , wherein the additional reflector  49  has flat upper surface  49   a  extending rearward along the optical axis Ax from a front end edge  49   c  positioned in the vicinity of the rear side focal point F of the projection lens  45  that reflects a part of reflected light from the reflector  47  towards the projection lens  45 ; and a shade portion  50  disposed on the front end edge  49   c  of the upper surface  49   a  of the additional reflector  49 , wherein the shade portion forms a cut-off line of a light distribution pattern by blocking a part of the reflected light from the reflector  47  and a part of the direct light from the LED  25 . 
     The LED  25  is a white light-emitting diode having a single light-emitting chip  25   a  whose size is about 1 millimeter (mm) square, for instance. The LED  25  is disposed rearward of the rear side focal point F of the projection lens  45 , and directed upward in the vertical direction on the optical axis Ax in the state where the LED  25  is supported by a substrate  33 . 
     As shown in  FIG. 3  and  FIG. 4 , the reflector  47  is a generally dome-shaped member provided on an upper side of the LED  25 . The reflector  47  has a reflective surface  47   a  that collects and reflects light L 1  from the LED  25  to the front towards the optical axis Ax. 
     The reflective surface  47   a  is formed in a shape of ellipsoidal reflective surface, in which the optical axis Ax is set as a central axis. Specifically, the reflective surface  47   a  has a vertical cross-section including the optical axis Ax that is set to be a generally ellipsoidal shape, and an eccentricity thereof is set to gradually increase from the vertical cross-section to a horizontal cross-section. 
     However, rear-side vertices of ellipses forming the respective cross-sections are set at the same position. The LED  25  is disposed on a first focal point of the ellipse forming the vertical cross-section of the reflective surface  47   a . Accordingly, the reflective surface  47   a  collects and reflects the light L 1  from the LED  25  to the front towards the optical axis Ax, and, at that time, the light is generally converged on a second focal point of the ellipse on the vertical cross-section including the optical axis Ax. 
     Further, a first reflective surface  53  that reflects a part of the direct light from the LED  25  downward to the front of the additional reflector  49  is formed on a tip portion of the reflector  47 , as shown in  FIG. 4 . 
     The first reflective surface  53  is formed further on a tip side of an effective reflective surface of the reflective surface  47   a  of the reflector  47 . The first reflective surface  53  has a front-side first reflective surface  51  and a rear-side first reflective surface  52 , which are divided in a longitudinal direction. 
     The front-side first reflective surface  51  is formed in a shape of ellipsoidal reflective surface having a vertical cross-section that is generally ellipsoidal in shape. The front-side first reflective surface  51  has a first focal point and a second focal point P that are respectively set to the LED  25  and a position above the rear-side focal point F of the projection lens  45 . The front-side first reflective surface  51  reflects the light from the LED  25  towards an upper-side second reflective surface  58  of a second reflective surface  60 . The second reflective surface  60  is formed on the front of the additional reflector  49 , which is provided with the shade portion  50  that forms a cut-off line of a light distribution pattern for left-side light distribution, and below the rear side focal point F of the projection lens  45 . 
     The rear-side first reflective surface  52  is formed in a shape of generally parabolic reflective surface having a vertical cross-section that is parabolic in shape. The rear-side first reflective surface  52  has a focal point that is set to the LED  25 . The rear-side first reflective surface  52  reflects the light from the LED  25  towards a lower-side second reflective surface  59  of the second reflective surface  60 . 
     The second reflective surface  60  is formed on the front of the additional reflector  49  and below the rear side focal point F of the projection lens  45 . The second reflective surface  60  reflects the reflected light from the first reflective surface  53  towards the projection lens  45  so that upward directed radiated light is emitted from the projection lens  45 . 
     Further, the second reflective surface  60  has the upper-side second reflective surface  58  and the lower-side second reflective surface  59 , which are divided in a vertical direction by an imaginary line shown in  FIG. 1  and  FIG. 5 . 
     Accordingly, the reflected light from the front-side first reflective surface  51  is incident on the upper-side second reflective surface  58 , and the reflected light from the rear-side first reflective surface  52  is incident on the lower-side second reflective surface  59 . Subsequently, the radiated light provided by the lower-side second reflective surface  59 , which is formed in a shape of generally curved surface having a curved vertical cross-section, radiates above the radiated light provided by the upper-side second reflective surface  58 , which is formed in a shape of generally flat surface having a linear vertical cross-section. 
     Note that the lower-side second reflective surface  59  is smoothly formed continuously to a lower portion of the upper-side second reflective surface  58 . 
     Further, the lamp unit  40  is structured such that reflected light L 3  reflected by the front-side first reflective surface  51  and the upper-side second reflective surface  58  radiates “4L, V, 4R” on 2U in a low-beam left-side light distribution pattern with a predetermined amount of light, and reflected light L 4  reflected by the rear-side first reflective surface  52  and the lower-side second reflective surface  59  radiates “8L, V, 8R” on 4U in the pattern with a predetermined amount of light, which is a requirement imposed by a European regulation (ECE R112) (refer to  FIG. 6 ). 
     Specifically, the light incident on the projection lens  45  from the upper-side second reflective surface  58  and the lower-side second reflective surface  59  is emitted as upward directed radiated light L 3 , L 4 , which radiate above the low-beam light distribution pattern PL. 
     Therefore, the vehicular lamp unit  40  can radiate the predetermined amount of reflected light with such a level that the light does not give a glare to a vehicle on the opposite lane, and also onto vertically divided two areas ( 2 UZ and  4 UZ) above the low-beam light distribution pattern PL. Accordingly, it is possible to improve the forward visibility by forming an optimum light distribution pattern. 
     The projection lens  45  is formed of a planoconvex lens that has a convex front side surface and a flat rear side surface. The projection lens  45  is disposed on the optical axis Ax so that the rear side focal point F thereof is positioned on a second focal point of the reflective surface  47   a  of the reflector  47 , as shown in  FIG. 3 . Accordingly, an image on a focal plane including the rear side focal point F is set to be projected forward as an inverted image. 
     In one or more embodiments, the additional reflector  49  has a shape of block that also serves as a supporting frame of the projection lens  45 , and is disposed between the projection lens  45  and the LED  25 , as shown in  FIG. 3  and  FIG. 5 . Further, the additional reflector  49  has the flat upper surface  49   a  that extends rearward from the front end edge  49   c  and reflects a part of the reflected light from the reflector  47  towards the projection lens  45 . A light control surface  36  to which reflective surface treatment is applied is formed on the upper surface  49   a.    
     Specifically, the additional reflector  49  is designed such that, by reflecting a part of the reflected light from the reflector  47  towards the projection lens  45  using the light control surface  36 , most of the light to be emitted upward from the projection lens  45  is converted into the light L 2  emitted downward from the projection lens  45 , thereby enhancing a luminous flux utilization factor of the light emitted from the LED  25 . 
     Specifically, the light control surface  36  is formed as a horizontal surface including the optical axis Ax, and the front end edge  49   c  (namely, an edge line between the light control surface  36  and a front end surface of the additional reflector  49 ) is formed so as to pass through the rear side focal point F of the projection lens  45 . 
     Further, of the light emitted from the LED  25 , a part of the light reflected by the reflective surface  47   a  of the reflector  47  is incident on the light control surface  36  of the additional reflector  49 , and the remainder of the light is incident directly on the projection lens  45 . At that time, the light incident on the light control surface  36  is incident on the projection lens  45  by being reflected upward by the light control surface  36 , and the light is emitted as the downward directed light L 2  from the projection lens  45 . 
     The shade portion  50  has a protrusion portion formed by protruding a part of the upper surface  49   a  of the additional reflector  49  formed as a horizontal surface including the optical axis Ax (right side portion of a vehicle) along the front end edge  49   c , as shown in  FIG. 4  and  FIG. 5 . 
     Specifically, the protrusion portion is formed of an oblique cut-off formation surface  50   a  extending obliquely upward by 15° in the right direction generally from the optical axis Ax (in the left direction as shown in  FIG. 5 ), a horizontal cut-off formation surface  50   b  extending horizontally in the right direction from the oblique cut-off formation surface  50   a  (in the left direction as shown in  FIG. 5 ), and a front end surface  50   c . A front end edge  49   d  (namely, an edge line between the horizontal cut-off formation surface  50   b  and the front end surface  50   c ) is formed so as to pass through the vicinity of the rear side focal point F of the projection lens  45 . 
     Accordingly, the front end edge  49   c  of the additional reflector  49  is formed in a curved shape in which lateral ends thereof protrude forward in a plan view so as to correspond to a field curvature of the projection lens  45 . The curved front end edge  49   c  coincides with a focal group of the projection lens  45 . Specifically, in the additional reflector  49 , the front end edge  49   c  of a left side portion of the vehicle and the front end edge  49   d  of the protrusion portion are formed along the focal group of the projection lens  45 , and shapes of the front end edges  49   c  and  49   d  directly correspond to a shape of the cut-off line. 
     Further, the front end edge  49   c  and the front end edge  49   d  are positioned in the vicinity of the rear side focal point F of the projection lens  45  to block a part of the reflected light from the reflector  47 , thereby forming a cut-off line of the left-side light distribution pattern. 
     Further, as shown in  FIG. 4  and  FIG. 5 , the additional reflector  49  has a blocking portion  65  in the vicinity of the shade portion  50  of the right side portion of the vehicle on the upper surface  49   a . The blocking portion  65  is formed to protrude upward from the upper surface  49   a . The blocking portion  65  operates to block a part of the reflected light from the reflector  47  and a part of the reflected light from the upper surface  49   a , as shown in  FIG. 4 . 
     Specifically, in the lamp unit  40  of one or more embodiments, a part of the reflected light from the reflector  47  is reflected by the upper surface  49   a  of the additional reflector  49 , and the light to be emitted upward from the projection lens  45  is converted into the light emitted downward from the projection lens  45 , thereby enhancing a luminous flux utilization factor of the light emitted from the LED  25 , as shown in  FIG. 3  and  FIG. 4 . 
     Further, even when the amount of light on the lower side of the cut-off line is increased as a whole as described above, because a part of the reflected light from the reflector  47  and a part of the reflected light from the upper surface  49   a  are blocked by the blocking portion  65 , a light-reduced area LZ is formed on a part of the lower side of a cut-off line of an opposite lane side, as shown in  FIG. 6 . 
     Here, a height of the blocking portion  65  is set so that reflected light from an upper end of an effective reflective surface of the reflective surface  47   a  of the reflector  47  is not blocked, and, accordingly, there is no chance to break the cut-off line of the opposite lane side. Therefore, it is possible to form the light-reduced area LZ on a part of the lower side of the cut-off line of the opposite lane side, while keeping the cut-off line. 
     Next, the lamp unit  20  will be described. 
     As shown in  FIG. 1 , the lamp unit  20  includes a light-emitting diode (not shown) as a light source, a reflector  27 , and a projection lens  35 . The light-emitting diode has the same structure as that of the LED  25  of the lamp unit  40 , and is disposed on an optical axis Ax and directed upward in the vertical direction. 
     The reflector  27  is a generally dome-shaped member provided on an upper side of the light-emitting diode. Further, the reflector  27  has a reflective surface having a shape of ellipsoidal reflective surface that diffuses and reflects light from the light-emitting diode to the front, with low light collecting power compared to that of the reflective surface  47   a  of the reflector  47 . 
     The projection lens  35  is formed of a planoconvex lens that has a convex front side surface and a flat rear side surface. The projection lens  35  is disposed on the optical axis Ax so that a rear side focal point of the projection lens  35  is positioned on a second focal point of the reflective surface of the reflector  27 , and accordingly, an image on a focal plane including the rear side focal point is set to be projected forward as an inverted image. Note that because the radiated light from the lamp unit  20  is only required to reach a relatively shorter distance, the projection lens  35  uses a lens whose diameter is smaller than that of the projection lens  45  of the lamp unit  40 . 
     Further, as shown in  FIG. 6 , the diffusion zone formation pattern WZ formed by the lamp unit  20  is a low-beam light distribution pattern for left-hand traffic having a cut-off line CL 1  of a vehicle&#39;s own lane side and a cut-off line CL 3  of an opposite lane side, which extend in a horizontal direction, and an oblique cut-off line CL 2 , on an upper end edge of the diffusion zone formation pattern WZ. 
     Further, the hot zone formation pattern HZ formed by the lamp unit  40  is formed to overlap with the diffusion zone formation pattern WZ, and is a hot zone formation pattern in which a light collecting power is higher than that in the diffusion zone formation pattern WZ. 
     Further, a light distribution pattern  2 UZ is a light distribution pattern in which the reflected light L 3  reflected by the front-side first reflective surface  51  and the upper-side second reflective surface  58  radiates “4L, V, 4R” on 2U in the low-beam left-side light distribution pattern with a predetermined amount of light. Further, a light distribution pattern  4 UZ is a light distribution pattern in which the reflected light L 4  reflected by the rear-side first reflective surface  52  and the lower-side second reflective surface  59  radiates “8L, V, 8R” on 4U in the low-beam left-side light distribution pattern with a predetermined amount of light. 
     Accordingly, the diffusion zone formation pattern WZ, the hot zone formation pattern HZ, and the light distribution patterns  2 UZ and  4 UZ overlap in the illustrated manner, thereby forming the low-beam light distribution pattern PL of the vehicular lamp  100  as a combined light distribution pattern. 
     Specifically, with the use of the vehicular lamp unit  40  of the vehicular lamp  100  according to one or more embodiments, a part of the reflected light from the reflector  47  is reflected by the upper surface  49   a  of the additional reflector  49 , and the light to be emitted upward from the projection lens  45  is converted into the light emitted downward from the projection lens  45 , thereby enhancing a luminous flux utilization factor of the light emitted from the LED  25 . 
     Further, in one or more embodiments, the shade portion  50  forming the cut-off line of the light distribution pattern is disposed on the front end edge  49   c  of the upper surface  49   a  of the additional reflector  49 . Also, the upper surface  49   a  of the additional reflector  49 , except the vicinity of the front end edge  49   c , is formed as a horizontal flat surface extending rearward along the optical axis Ax. 
     As a result of this, almost all of the reflected light L 2  reflected by the upper surface  49   a  of the additional reflector  49  corresponds to light reflected by a simple horizontal surface, so that it is possible to reduce a luminescent unevenness of the light distribution pattern by reducing the light reflected by the oblique cut-off formation surface (inclined surface)  50   a  of the shade portion  50  that inclines in a lateral direction. 
     Further, the shade portion  50  of the vehicular lamp unit  40  has the protrusion portion formed by protruding a part of the upper surface  49   a  of the additional reflector  49  formed as a horizontal surface including the optical axis Ax along the front end edge  49   c.    
     Accordingly, the light reflected by the upper surface  49   a  of the additional reflector  49 , which is formed as a horizontal surface including the optical axis Ax, is emitted via a portion towards a center of the projection lens  35 , so that the light is likely to converge in the vicinity of the cut-off line of the hot zone formation pattern HZ. Accordingly, it is possible to improve a distance visibility by making a hot zone of the light distribution pattern provided by the additional reflector  49  appear in the vicinity of the cut-off line. 
     Further, the first reflective surface  53  is positioned further on the LED  25  side relative to the rear side focal point F of the projection lens  45  and is formed close to the LED  25 , so that a size of the first reflective surface  53  can be reduced. Further, a light source image of the reflected light from the first reflective surface  53  close to the LED  25  becomes large, which enables weak light to be radiated over a wide range above H line. 
     Further, the lamp unit  40  of one or more embodiments is used as a light collecting-type lamp unit having the highest light collecting power in the vehicular lamp  100  that combines a light distribution from another lamp unit  20  having a light collecting power lower than that of the lamp unit  40  to form the entire low-beam light distribution pattern PL. 
     Accordingly, in case of the vehicular lamp  100  that combines the light distributions from the plurality of lamp units  20 ,  40  to form the entire low-beam light distribution pattern PL, by forming the upper surface  49   a  of the additional reflector  49  in the light collecting-type lamp unit  40  having a light collecting power higher than that of another lamp unit  20  in a horizontal surface including the optical axis Ax, it is possible to improve the distance visibility by making the hot zone appear in the vicinity of the cut-off line. 
     Next, a modified example of the lamp unit according to one or more embodiments will be described. 
       FIG. 7  is an upper perspective view of an additional reflector, which is a modified example of the additional reflector shown in  FIG. 2 . Note that constituent portions that are generally the same as those of the additional reflector  49  of the aforementioned embodiments are denoted by the same reference numerals, and a detailed explanation thereof will be omitted. 
     An additional reflector  70  of the example shown in  FIG. 7  is designed such that, similar to the additional reflector  49  of the aforementioned embodiments, by reflecting a part of the reflected light from the reflector  47  to the projection lens  45  using the light control surface  36 , most of the light is converted to be emitted upward from the projection lens  45  into the light L 2  emitted downward from the projection lens  45 , thereby enhancing a luminous flux utilization factor of the light emitted from the LED  25 . 
     A shade portion  75  of the additional reflector  70  has a caved portion formed by caving a part of an upper surface  70   a  of the additional reflector  70  formed as a horizontal surface parallel to the optical axis Ax (left side portion of a vehicle) along a front end edge  70   c.    
     Specifically, the caved portion is formed of an oblique cut-off formation surface  75   a  extending obliquely upward by 15° in the right direction generally from the optical axis Ax (in the left direction in  FIG. 7 ), a horizontal cut-off formation surface  75   b  extending horizontally in the left direction generally from the optical axis Ax (in the right direction in  FIG. 7 ), and a front end surface  75   c . A front end edge  70   d  is formed so as to pass through the rear side focal point F of the projection lens  45 . 
     The front end edge  70   c  of the additional reflector  70  is formed in a curved shape in which lateral ends thereof protrude forward in a plan view so as to correspond to a field curvature of the projection lens  45 . The curved front end edge  70   c  coincides with a focal group of the projection lens  45 . Specifically, in the additional reflector  70 , the front end edge  70   c  of a right side portion of the vehicle and the front end edge  70   d  of the caved portion are formed along the focal group of the projection lens  45 , and the shapes of the front end edges  70   c  and  70   d  directly correspond to the shape of the cut-off line. 
     Further, the front end edge  70   c  and the front end edge  70   d  are positioned in the vicinity of the rear side focal point F of the projection lens  45  to block a part of the reflected light from the reflector  47 , thereby forming a cut-off line of a left-side light distribution pattern. 
     Further, the additional reflector  70  has a blocking portion  65  in the vicinity of the shade portion  75  of the right side portion of the vehicle on the upper surface  70   a . The blocking portion  65  is formed to protrude upward from the upper surface  70   a . The blocking portion  65  operates to block a part of the reflected light from the reflector  47  and a part of the reflected light from the upper surface  70   a.    
     Specifically, the shade portion  75  forming the cut-off line of the light distribution pattern is disposed on the front end edge  70   c  of the upper surface  70   a  of the additional reflector  70 . Also, the upper surface  70   a  of the additional reflector  70 , except the vicinity of the front end edge  70   c , is formed as a horizontal flat surface extending rearward, in parallel with the optical axis Ax, spaced slightly above the optical axis Ax. 
     As a result of this, almost all of the reflected light L 2  reflected by the upper surface  70   a  of the additional reflector  70  corresponds to light reflected by a simple horizontal surface, so that it is possible to reduce a luminescent unevenness of the light distribution pattern by reducing the light reflected by the oblique cut-off formation surface (inclined surface)  75   a  of the shade portion  75  that inclines in a lateral direction. 
     Those skilled in the art will appreciate the vehicular lamp unit and the vehicular lamp of the present invention may be varied in many ways within the spirit of the present invention. 
     For instance, although the vehicular lamp  100  of the aforementioned embodiments is structured such that the plurality of lamp units are housed side-by-side in the lamp chamber. The present invention is not limited to this, and a single lamp unit may be used. Further, the light source is not limited to a semiconductor light-emitting element such as a light-emitting diode. Rather, a discharge bulb such as a metal halide bulb and a halogen bulb may also be used. 
     While description has been made in connection with exemplary embodiments of the present invention, it will be obvious to those skilled in the art that various changes and modification may be made therein without departing from the present invention. It is aimed, therefore, to cover in the appended claims all such changes and modifications falling within the true spirit and scope of the present invention. 
     DESCRIPTION OF THE REFERENCE NUMERALS 
     
         
         
           
               20  LAMP UNIT (ANOTHER VEHICULAR LAMP UNIT) 
               25  LED (LIGHT SOURCE) 
               36  LIGHT CONTROL SURFACE 
               40  LAMP UNIT (VEHICULAR LAMP UNIT) 
               45  PROJECTION LENS 
               47  REFLECTOR 
               49  ADDITIONAL REFLECTOR 
               49   a  UPPER SURFACE 
               49   c  FRONT END EDGE 
               50  SHADE PORTION 
               50   a  OBLIQUE CUT-OFF FORMATION SURFACE 
               50   b  HORIZONTAL CUT-OFF FORMATION SURFACE 
               50   c  FRONT END SURFACE 
               51  FRONT-SIDE FIRST REFLECTIVE SURFACE 
               52  REAR-SIDE FIRST REFLECTIVE SURFACE 
               53  FIRST REFLECTIVE SURFACE 
               58  UPPER-SIDE SECOND REFLECTIVE SURFACE 
               59  LOWER-SIDE SECOND REFLECTIVE SURFACE 
               60  SECOND REFLECTIVE SURFACE 
               65  BLOCKING PORTION 
               100  VEHICULAR LAMP 
             Ax OPTICAL AXIS 
             CL CUT-OFF LINE 
             CL 1  CUT-OFF LINE OF VEHICLE&#39;S OWN LANE SIDE 
             CL 2  OBLIQUE CUT-OFF LINE 
             CL 3  CUT-OFF LINE OF OPPOSITE LANE SIDE 
             F REAR-SIDE FOCAL POINT