Patent Publication Number: US-8531108-B2

Title: Headlamp for vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority from Japanese Patent Application No. 2010-204591, filed on Sep. 13, 2010, the content of which is hereby incorporated by reference in its entirety into this application. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     The present invention relates generally to headlamps for vehicles which include a heat dissipating member for dissipating heat generated by a light source. More particularly, the invention relates to headlamp&#39;s for vehicles which employ a light source that has high heat-generating density and is lowered in luminous efficiency and shortened in service life at high temperature. 
     2. Description of the Related Art 
     Japanese Patent Application Publication No. 2004-311224 discloses a headlamp for a vehicle which employs LEDs (Light Emitting Diodes) as lighting sources. The headlamp includes a plurality of light emitting units each of which has a projection lens, a reflector and an LED that are sequentially arranged from the front side. The headlamp further includes a heat dissipating member (or support member) that has all of the LEDs of the light emitting units mounted thereon, so as to dissipate heat generated by the LEDs during operation. In addition, the headlamp also includes a housing in which all of the light emitting units are accommodated. 
     With the above headlamp, however, it may be necessary to arrange a lighting control circuit, which controls the lighting of the LEDs, outside the housing and thus away from the LEDs. Consequently, the electric resistance between the LEDs and the lighting control circuit will be high. Moreover, when a temperature sensing element is arranged in the vicinity of the LEDs for sensing the temperature of the LEDs, it is necessary to electrically connect the temperature sensing element to the lighting control circuit using signal lines that extend through the housing. Consequently, the wiring process of the headlamp will be complicated. Furthermore, to effectively dissipate heat generated by the lighting control circuit, it may be necessary to arrange an additional heat dissipating member for the lighting control circuit outside the housing, thereby increasing both the parts count and size of the headlamp. 
     Japanese Patent Application Publication No. 2003-68134 discloses a headlamp which includes a discharge bulb as a light source, a lighting control circuit for controlling the lighting of the discharge bulb, a heat dissipating member for dissipating heat generated by the lighting control circuit, and a housing that accommodates therein all of the discharge bulb, the lighting control circuit and the heat dissipating member. 
     With the above headlamp, it is possible to arrange the lighting control circuit in the vicinity of the discharge bulb. However, to effectively dissipate heat generated by the discharge bulb, it may be necessary to arrange an additional heat dissipating member for the discharge bulb. Consequently, when not properly designed, both the parts count and size of the headlamp will be increased. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided a headlamp for a vehicle. The headlamp includes: a housing having a front opening; a lens cover arranged to cover the front opening of the housing; a lamp chamber defined by the housing and the lens cover; a light source provided in the lamp chamber; a lighting control circuit configured to control lighting of the light source; and a heat dissipating member arranged in the lamp chamber to dissipate heat generated by the light source. Further, in the headlamp, the lighting control circuit is formed on a substrate. The heat dissipating member has a pillar portion and a plurality of heat dissipating fins. The pillar portion has the light source mounted thereto. The heat dissipating fins are provided on an outer periphery of the pillar portion so as to be spaced from one another. The pillar portion also has a recess formed therein. The substrate is received in the recess of the pillar portion. 
     With the above configuration, both the heat generated by the light source and the heat generated by the lighting control circuit will be first transferred to the pillar portion and then dissipated via the heat dissipating fins. That is to say, it is possible to effectively dissipate both the heat generated by the light source and the heat generated by the lighting control circuit via the single heat dissipating member. Consequently, it becomes possible to minimize both the parts count and size of the headlamp while ensuring effective dissipation of both the heat generated by the light source and the heat generated by the lighting control circuit. In addition, since both the light source and the lighting control circuit are arranged within the lamp chamber, the wiring process of the headlamp can be simplified. 
     Preferably, the recess is formed to extend along the longitudinal direction of the pillar portion; the substrate is received in the recess with the longitudinal direction of the substrate coinciding with that of the pillar portion. 
     The lighting control circuit may include a plurality of high-heat-generating elements and a plurality of low-heat-generating elements that generate less heat than the high-heat-generating elements. In this case, the distances from the high-heat-generating elements to an interior surface of the pillar portion which defines the recess are preferably set to be less than a predetermined value. Further, the high-heat-generating elements are preferably located closer to a longitudinal axis of the pillar portion than the low-heat-generating elements are. 
     The recess of the pillar portion is preferably so formed that the shape of the recess conforms to that of the substrate on which the lighting control circuit is formed. 
     The light source may be mounted on an upper end face of the pillar portion of the heat dissipating member. 
     Alternatively, the heat dissipating member may further have a heat dissipating plate mounted on the upper end face of the pillar portion. The light source may be mounted to the heat dissipating plate. 
     Still alternatively, the light source may be mounted on a front part of a side surface of the pillar portion. 
     The recess may be formed in the side surface of the pillar portion to have an opening that opens on the side surface. In this case, the heat dissipating fins are preferably arranged on the side surface of the pillar portion except for the opening of the recess so as to each extend radially from the side surface. 
     Preferably, the pillar portion further has an injection hole formed therein, through which a filling material is injected in the recess. 
     It is preferable that the substrate has a temperature sensing element mounted thereon. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood more fully from the detailed description given hereinafter and from the accompanying drawings of preferred embodiments of the invention, which, however, should not be taken to limit the invention to the specific embodiments but are for the purpose of explanation and understanding only. 
       In the accompanying drawings: 
         FIG. 1  is a schematic vertical cross-sectional view of a headlamp for a vehicle according to a first embodiment of the invention; 
         FIG. 2  is a cross-sectional view taken along the line A-A in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view taken along the line B-B in  FIG. 1 ; 
         FIG. 4  is a schematic horizontal cross-sectional view of the headlamp; 
         FIG. 5  is a perspective view of a heat dissipating member of the headlamp from the rear side; 
         FIG. 6  is a rear end view of the heat dissipating member; 
         FIG. 7  is a top view of the heat dissipating member; 
         FIGS. 8A-8E  are cross-sectional views taken along the line C-C in  FIG. 6 ; 
         FIG. 9  is a cross-sectional view taken along the line D-D in  FIG. 6 ; 
         FIG. 10  is an enlarged cross-sectional view taken along the line E-E in  FIG. 3 ; 
         FIG. 11  is a vertical cross-sectional view showing the configuration of a heat dissipating member according to a second embodiment of the invention; 
         FIG. 12  is an enlarged cross-sectional view taken along the line F-F in  FIG. 11 ; 
         FIGS. 13A-13D  are schematic views respectively showing the configurations of pillar portions according third to sixth embodiments of the invention; 
         FIG. 14  is a perspective view of a heat dissipating member according to a seventh embodiment of the invention; 
         FIG. 15A  is a vertical cross-sectional view of the heat dissipating member according to the seventh embodiment; and 
         FIG. 15B  is a vertical cross-sectional view illustrating a modification of the heat dissipating member according to the seventh embodiment. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows the overall configuration of a headlamp according to the first embodiment of the invention. 
     The headlamp includes a housing  1  that has a front opening  2  and is closed by a lower wall  1   a , a rear wall  1   b  and an upper wall  1   c  except for the front opening  2 . Further, a lens cover  4  is arranged to cover the front opening  2 , thereby completely closing the housing  1 . Consequently, a lamp chamber  6  is defined by the housing  1  and the lens cover  4 . 
     Within the lamp chamber  6 , a projection lens  8 , a shade  10  and a light source  12  are sequentially arranged along an optical axis Z of the headlamp from the front side to the rear side. Further, a reflector  14  is also arranged in the lamp chamber  6  so as to face the light source  12 . The reflector  14  is provided to reflect light emitted by the light source  12 . 
     In the present embodiment, the projection lens  8  is implemented by a plano-convex lens. The reflector  14  has an inside reflecting surface that is curved into, for example, a paraboloid of revolution. The projection lens  8  and the reflector  14  are positioned with respect to each other so that the focal point of the projection lens  8  is at substantially the same position as that of the reflector  14 . Part of the light emitted by the light source  12  and reflected by the reflector  14  is blocked by the shade  10 ; the remaining part of the light is projected forward by the projection lens  8 . In addition, in the present embodiment, the shade  10  also functions as a supporting member to support the projection lens  8 . 
     It should be noted that though the headlamp according to the present embodiment is a projector-type headlamp which includes the projection lens  8  and the reflector  14 , the invention may also be applied to reflector-type and direct projection-type headlamps. 
     Moreover, in the present embodiment, the light source  12  is implemented by an LED (Light Emitting Diode). Further, the light source  12  is disposed on a heat dissipating member  16  that is also received in the lamp chamber  6 . 
     More specifically, in the present embodiment, as shown in  FIGS. 1-4 , the heat dissipating member  16  is configured to include a pillar portion  18  and a plurality of heat dissipating fins  20 . The pillar portion  18  has a cylindrical shape and is mounted on a supporting member  24  so as to extend in the vertical direction; the supporting member  24  is mounted on the lower wall  1   a  of the housing  1 . The light source  12  is mounted on an upper end face Of the pillar portion  18 . 
     The heat dissipating fins  20  are plate-shaped and provided on the radially outer periphery of the pillar portion  18 . More specifically, as shown in  FIGS. 5-7 , the heat dissipating fins  20  each extend from the radially outer periphery of the pillar portion  18  with the longitudinal direction thereof coinciding with the vertical direction (or the axial direction of the pillar portion  18 ). The heat dissipating fins  20  are spaced in the circumferential direction of the pillar portion  18  at predetermined intervals so as to allow air to flow between each adjacent pair of the heat dissipating fins  20 . In the present embodiment, the length of the heat dissipating fins  20  in the vertical direction is set to be equal to that of the pillar portion  18 . In other words, the heat dissipating fins  20  extend over the entire axial length of the pillar portion  18 . Moreover, between the lower ends of the heat dissipating fins  20  and the lower wall  1   a  of the housing  1 , there is formed such a sufficient gap as to allow air to flow through the gap; the length of the gap in the vertical direction is equal to that of the supporting member  24 . 
     It should be noted that though the length of the heat dissipating fins  20  is set to be equal to that of the pillar portion  18  in the present embodiment, the length of the heat dissipating fins  20  may also be set to other values as needed. It also should be noted that though the pillar portion  18  has the cylindrical shape in the present embodiment, it may also have other shapes, for example a square or hexagonal prismatic shape. In addition, when the pillar portion  18  is configured to have a prismatic shape, the heat dissipating fins  20  may be provided on the flat side surfaces of the pillar portion  18  so as to vertically extend parallel with one another. 
     The heat dissipating fins  20  may be made of a material having high heat conductivity, such as aluminum. In the present embodiment, the heat dissipating fins  20  are integrally formed with the pillar portion  18  by aluminum casting. However, it should be noted that the heat dissipating fins  20  may also be separately formed from the pillar portion  18  using an aluminum plate and then joined to the pillar portion  18  by, for example, brazing. 
     The pillar portion  18  has a recess  26  that is formed in the side surface of the pillar portion  18  so as to extend in the vertical direction (or the axial direction of the pillar portion  18 ). The recess  26  has an opening  30  that opens on the side surface of the pillar portion  18  and faces backward. Within the recess  26 , there is received a substrate  28  on which a lighting control circuit  31  for controlling the lighting of the light source  12  is formed. 
     The lighting control circuit  31  is composed of various elements mounted on the substrate  28 ; those elements include high-heat-generating elements  32  and low-heat-generating elements  34  that generate less heat than the high-heat-generating elements  32  during operation. On the substrate  28 , there is also mounted a temperature sensing element  36 . 
     The temperature sensing element  36  is located on the substrate  28  so that when the substrate  28  is received in the recess  26  of the pillar portion  18 , the temperature sensing element  36  is in the vicinity of the light source  12 . More specifically, in the present embodiment, as shown in  FIG. 1 , the temperature sensing element  36  is positioned closest to the light source  12  among all the elements mounted on the substrate  28 . 
     It should be noted that the substrate  28  is not necessarily completely received in the recess  26  of the pillar portion  18 . In other words, the substrate  28  may also be partially received in the recess  26 . However, even in this case, it is preferable that at least the high-heat-generating elements  32  are received in the recess  26 . 
     Moreover, when the substrate  28  is received in the recess  26  of the pillar portion  18 , the high-heat-generating elements  32  are located closer to the longitudinal axis  180  of the pillar portion  18  than the low-heat-generating elements  34  are (see  FIG. 10 ). 
     In the present embodiment, as shown in  FIGS. 4 and 7 , the heat dissipating fins  20  are left-right symmetrically arranged on the side surface of the pillar portion  18  without interfering with the opening  30  of the recess  26  and the shade  10 . Moreover, each of the heat dissipating fins  20  radially extends from the side surface of the pillar portion  18 . 
     The recess  26  of the pillar portion  18  is formed so that when the substrate  28  is received in the recess  26 , the distances between the heat-generating elements  32  and  34  of the lighting control circuit  31  and the interior surface of the pillar portion  18  which defines the recess  26 , especially the distances between the high-heat-generating elements  32  and the interior surface are sufficiently small. 
     For example, referring to  FIG. 8A , when the height of the high-heat-generating elements  32  is less than that of the low-heat-generating elements  34 , the recess  26  may be stepped on both the left and right sides to have a small-width portion  26   a  and a large-width portion  26   b ; the small-width portion  26   a  has a smaller width than the large-width portion  26   b  in the left-right direction and is positioned forward of the large-width portion  26   b . Consequently, the distances between the interior surface of the pillar portion  18  and the high-heat-generating elements  32 , which are received in the small-width portion  26   a  of the recess  26 , can be reduced. 
     Further, as shown in  FIG. 8B , the recess  26  may also be formed to penetrate the pillar portion  18  in the front-rear direction so that the small-width portion  26   a  has an opening on a front part of the side surface of the pillar portion  18 . 
     On the other hand, referring to  FIG. 8C , when the height of the high-heat-generating elements  32  is equal to that of the low-heat-generating elements  34 , the recess  26  may be formed to have only a single width in the left-right direction. In this case, the recess  26  has a rectangular cross section perpendicular to the axial direction of the pillar portion  18 . 
     Furthermore, referring to  FIG. 8D , when the heights of the heat-generating elements  32  and  34  gradually decrease from the front side to the rear side, the recess  26  may be formed so as to taper forward. 
     Referring to  FIG. 8E , when all the elements are mounted on the same side of the substrate  28  and the high-heat-generating elements  32  have a smaller height than and is positioned forward of the low-heat-generating elements  34 , the recess  26  may be stepped on only one of the left and right sides. 
     As described above, it is preferable to design the horizontal cross-sectional shape of the recess  26  according to the shapes of the elements  32 ,  34  and  36  mounted on the substrate  28 , thereby minimizing the distances between the high-heat-generating elements  32  and the interior surface of the pillar portion  18  which defines the recess  26 . 
     Further, in either of the above-described cases, it is preferable that the distances between the interior surface of the pillar portion  18  and the high-heat-generating elements  32  are in the range of 0.5 to 1.0 mm. 
     Moreover, it is also preferable to design the vertical cross-sectional shape of the recess  26  according to the shapes of the elements  32 ,  34  and  36 , thereby further effectively minimizing the distances between the high-heat-generating elements  32  and the interior surface of the pillar portion  18  which defines the recess  26 . 
     Referring now to  FIG. 9 , in the present embodiment, the pillar portion  18  further has an injection hole  37  that is formed in the lower end face of the pillar portion  18  so as to communicate with the recess  26 . Through the injection hole  37 , a filling material, such as a heat-conductive gel, is injected in the recess  26 , thereby filling the void space in the recess  26 . 
     It should be noted that the filling material may be injected to fill the void space in the recess  26  either completely or partially. However, even in the latter case, it is preferable that at least the gaps between the high-heat-generating elements  32  and the interior surface of the pillar portion  18  which defines the recess  26  are filled with the filling material. 
     Moreover, in the present embodiment, as shown in  FIG. 10 , a cap  38  is mounted to the pillar portion  18  so as to close the opening  30  of the recess  26 . With the cap  38 , it is possible to prevent foreign matter, such as water and dust, from intruding into the recess  26 . In addition, with the cap  38 , during the injection of the filling material into the recess  26  via the injection hole  37 , it is possible to prevent the filling material from leaking out of the recess  26  via the opening  30 . 
     Furthermore, as shown in  FIG. 1 , a lead wire  42 , which has one end connected to a connector  40  provided on the substrate  28 , is extended through the cap  38  and the rear wall  1   b  of the housing  1 , so as to have the other end located outside the housing  1 . The other end of the lead wire  42  is then electrically connected to a power source  45  via a connector  45  provided on the outside of the housing  1 . 
     After having described the configuration of the headlamp according to the present embodiment, operation thereof will be described hereinafter. 
     The light source  12  emits light upon being lighted up by the lighting control circuit  31 . The light emitted by the light source  12  is then reflected by the reflector  14 . Part of the light reflected by the reflector  14  is blocked by the shade  10 ; the remaining part of the light is projected forward by the projection lens  8 , thereby illuminating the road ahead. 
     Moreover, during the operation, the light source  12 , which is mounted on the upper end face of the pillar portion  18 , generates heat; the generated heat is then directly transferred to the pillar portion  18 . On the other hand, the high-heat-generating elements  32  of the lighting control circuit  31 , which are mounted on the substrate  28  and received in the recess  26  of the pillar portion  18 , also generate heat; the generated heat is then transferred to the pillar portion  18  via the filling material filled in the recess  26 . 
     As indicated with arrows in  FIG. 10 , the heat transferred to the pillar portion  18  from the light source  12  and the high-heat-generating elements  32  is further transferred to the heat dissipating fins  20 . In addition, it should be noted that only a small part of the heat generated by the high-heat-generating elements  32  is dissipated to the internal space of the lamp chamber  6  via the cap  38  that covers the opening  30  of the recess  26 . 
     The heat transferred from the pillar portion  18  to the heat dissipating fins  20  is then dissipated by the fins  20 . Consequently, the air around the heat dissipating fins  20  is warmed up and thereby expanded. The air then flows toward the upper wall  1   c  of the housing  1  through the spaces between the heat dissipating fins  20 . Thereafter, as indicated with arrows in  FIG. 1 , the air flows forward along the upper wall  1   c  of the housing  1  to the lens cover  4  which closes the front opening  2  of the housing  1 . In addition, at this stage, the air is prevented by the reflector  14  and the shade  10  from flowing downward. 
     Further, the air flows downward along the inner surface of the lens cover  4 , and then flows backward to the heat dissipating fins  20  through the space between the shade  10  and the lower wall  1   a  of the housing  1 . 
     As a result, the air warmed up by the heat dissipated by the heat dissipating fins  20  is cooled by heat exchange with outside air via the rear wall  1   b , upper wall  1   c , lower wall  1   a  and side walls of the housing  1  as well as via the lens cover  4 . 
     After reaching the heat dissipating fins  20 , the cooled air turns to flow upward through the spaces between the heat dissipating fins  20 . Consequently, the air is again warmed up and expanded by the heat dissipated by the heat dissipating fins  20 . Thus, there is formed a circulation path along which air inside the housing  1  flows; during its flow along the circulation path, the air is warmed up by the heat dissipated by the heat dissipating fins  20  and cooled by the heat exchange with outside air via the walls of the housing  1  and the lens cover  4 . As a result, with the air flow along the circulation path, both the heat generated by the heat source  12  and the heat generated by the high-heat-generating elements  32  can be continuously removed to the outside of the housing  1 . 
     Furthermore, in the present embodiment, the lighting control circuit  31  includes the temperature sensing element  36  that is mounted on the substrate  28  to sense the ambient temperature of the light source  12  and the lighting control circuit  31 . When the ambient temperature sensed by the temperature sensing element  36  is higher than or equal to a predetermined temperature, the lighting control circuit  31  controls the amount of electric power supplied to the light source  12  so as to suppress the heat generated by the light source  12  and the lighting control circuit  31 . 
     Consequently, even when the temperature outside the housing  1  is high, it is still possible to prevent the ambient temperature of the lighting source  12  and the lighting control circuit  31  from exceeding the predetermined temperature, thereby ensuring durability of the light source  12  and the lighting control circuit  31 . 
     In addition, during running of the vehicle, the outside air comes to hit against the outer surface of the lens cover  4 , thereby enhancing the heat exchange between the outside air and the air in the lamp chamber  6 . Moreover, when the outside temperature is so low that snow or ice comes to deposit on the outer surface of the lens cover  4 , it is possible to melt the snow or ice with the heat transferred from the air in the lamp chamber  6 , thereby reliably illuminating the road ahead. 
     According to the present embodiment, it is possible to achieve the following advantages. 
     In the present embodiment, the heat dissipating member  16  is arranged in the lamp chamber  6  and configured to include the pillar portion  18  and the heat dissipating fins  20 . The pillar portion  18  has the light source  12  mounted thereto, more specifically mounted on the upper end face thereof. The heat dissipating fins  20  are formed on the radially outer periphery of the pillar portion  18  so as to be spaced from one another. The lighting control circuit  31 , which controls the lighting of the light source  12 , is formed on the substrate  28 . The pillar portion  18  also has the recess  26  formed therein. The substrate  28  is received in the recess  26 . 
     With the above configuration, both the heat generated by the light source  12  and the heat generated by the lighting control circuit  31  will be first transferred to the pillar portion  18  and then dissipated via the heat dissipating fins  20 . That is to say, it is possible to effectively dissipate both the heat generated by the light source  12  and the heat generated by the lighting control circuit  31  via the single heat dissipating member  16 . Consequently, it becomes possible to minimize both the parts count and size of the headlamp while ensuring effective dissipation of both the heat generated by the light source  12  and the heat generated by the lighting control circuit  31 . In addition, since both the light source  12  and the lighting control circuit  31  are arranged within the lamp chamber  6 , the wiring process of the headlamp can be simplified. 
     Moreover, in the present embodiment, the recess  26  is formed to extend along the longitudinal direction (or the axial direction) of the pillar portion  18 . The substrate  28  is received in the recess  26  so that the longitudinal direction of the substrate  28  coincides with that of the recess  26 . 
     With the above configuration, it is possible to form the recess  26  in the pillar portion  18  and arrange the substrate  28  in the recess  26  without increasing the size of the pillar portion  18 . 
     In the present embodiment, the lighting control circuit  31  includes the high-heat-generating elements  32  and the low-heat-generating elements  34  that generate less heat than the high-heat-generating elements  32 . Further, when the substrate  28  is received in the recess  26 , the high-heat-generating elements  32  are positioned closer to the longitudinal axis  180  of the pillar portion  18  than the low-heat-generating elements  34  are. 
     With the above configuration, it is possible to enhance the heat transfer from the high-heat-generating elements  32  to the pillar portion  18 , thereby effectively dissipating the heat generated by the high-heat-generating elements  32 . 
     Further, the distances from the high-heat-generating elements  32  to the interior surface of the pillar portion  18  which defines the recess  26  are set to be less than a predetermined value (e.g., 1 mm in the present embodiment). 
     Setting the distances as above, it is possible to ensure effective heat transfer from the high-heat-generating elements  32  to the pillar portion  18 . 
     In the present embodiment, as illustrated in  FIGS. 8A-8E , the recess  26  is so formed that the shape of the recess  26  conforms to that of the substrate  26  on which the lighting control circuit  31  is formed. 
     With the above configuration, it is possible to minimize the distances between the elements  32  and  34  of the lighting control circuit  31  and the interior surface of the pillar portion  18  which defines the recess  26 . 
     In the present embodiment, the pillar portion  18  has the injection hole  37  formed therein. 
     Consequently, with the injection hole  37 , it is possible to easily fill the filling material into the recess  26 . Further, with the filling material filled in the recess  26 , it is possible to more effectively transfer the heat generated by the high-heat-generating elements  32  to the interior surface of the pillar portion  18  which defines the recess  26 . 
     In the present embodiment, the substrate  28  has the temperature sensing element  36  mounted thereon. 
     Consequently, it is possible to easily connect the temperature sensing element  36  to the lighting control circuit  31  which is also provided on the substrate  28 . Moreover, the lighting control circuit  31  can suitably control the amount of electric power supplied to the light source  12  based on the temperature sensed by the temperature sensing element  36 . 
     Next, other embodiments of the present invention will be described with reference to  FIGS. 11-15 . It should be noted that for the sake of clarity and understanding, identical components having identical functions in different embodiments of the invention have been marked, where possible, with the same reference numerals in each of the figures and that for the sake of avoiding redundancy, descriptions of the identical components will not be repeated. 
       FIGS. 11 and 12  together show the configuration of a heat dissipating member  46  according to the second embodiment of the invention. As shown in the figures, the heat dissipating member  46  has a pillar portion  48  that is comprised of a cylindrical part  50  and a square-prismatic part  52 . 
     The cylindrical part  50  is lower than the square-prismatic part  52 . The light source  12  is mounted on the upper end face of the cylindrical part  50 . 
     The square-prismatic part  52  is integrally formed with and positioned backward of the cylindrical part  50 . The height (or the length in the vertical direction) of the square-prismatic part  52  is substantially twice that of the cylindrical part  50 . The square-prismatic part  52  has a recess  26  formed in the side surface thereof. The recess  26  has an opening  30  that opens on the side surface of the square-prismatic part  52  and faces backward. The substrate  28  is received in the recess  26  so that the longitudinal direction of the substrate  28  coincides with that of the recess  26 . 
     With the above heat dissipating member  46 , it is possible to more easily make up a projector-type headlamp for a vehicle. 
       FIG. 13A  shows the configuration of a pillar portion  58  according to the third embodiment of the invention. As shown in the figure, the side surface of the pillar portion  58  includes a flat area  60  on the front and upper side. The light source  12  is mounted on the flat area  60  so as to face forward. 
     With the above configuration, it is possible to easily make up a direct projection-type headlamp for a vehicle. 
       FIG. 13B  shows the configuration of a pillar portion  68  according to the fourth embodiment of the invention. As shown in the figure, the side surface of the pillar portion  68  includes a flat area  62  on the front side; the flat area  62  extends over the entire length of the pillar portion  68  in the vertical direction. The light source  12  is mounted on an upper part of the flat area  62  so as to face forward. 
       FIG. 13C  shows the configuration of a pillar portion  78  according to the fifth embodiment of the invention. As shown in the figure, the recess  26  is formed in a front part of the side surface of the pillar portion  78  so that the opening  30  of the recess  26  faces forward. 
     With the above configuration, it is possible to provide the heat dissipating fins  20  on the entire rear part of the side surface of the pillar portion  78 , thereby increasing the total number of the heat dissipating fins  20  provided on the side surface. 
       FIG. 13D  shows the configuration of a pillar portion  88  according to the sixth embodiment of the invention. As shown in the figure, the recess  26  is formed in a left part of the side surface of the pillar portion  88  so that the opening  30  of the recess  26  faces leftward. 
     With the above configuration, it is possible to symmetrically arrange the pillar portion  88  and another pillar portion  88 , which has the recess  26  formed in a right part of the side surface thereof, close to each other with the openings  30  thereof facing each other. 
       FIGS. 14 and 15A  shows the configuration of a heat dissipating member  56  according to the seventh embodiment of the invention. As shown in the figures, the heat dissipating member  56  has a heat dissipating plate  14  mounted on the upper end face of the pillar portion  18 . The heat dissipating plate  14  has, for example, a circular shape. The light source  12  is mounted on a front part of the upper end face of the heat dissipating plate  14 . 
     With the above heat dissipating member  56 , it is possible to easily make up a reflector-type headlamp for a vehicle. In addition, as shown in  FIG. 15B , the light source  12  may also be mounted on a front part of the lower end face of the heat dissipating plate  14 . 
     While the above particular embodiments have been shown and described, it will be understood by those skilled in the art that various modifications, changes, and improvements may be made without departing from the spirit of the invention.