Patent Publication Number: US-9885455-B2

Title: Vehicle lamp

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority from Japanese Patent Application No. 2015-113231 filed on Jun. 3, 2015, with the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a vehicle lamp. In particular, the present disclosure relates to a vehicle lamp used for vehicles such as, for example, cars. 
     BACKGROUND 
     A vehicle lamp conventionally known in the related art includes a substrate mounted with a light emitting diode (LED) thereon as a light source, a heat dissipating plate disposed on a surface of the substrate at a side opposite to the light source mounting surface, and a reflector disposed at the light source mounting surface side of the substrate (see, e.g., Japanese Patent Laid-Open Publication No. 2015-046235). 
     SUMMARY 
     In the vehicle lamp having the above-described structure, the substrate, the heat dissipating plate, and the reflector are generally fixed to each other by fastening members such as, for example, screws. Through repeated intensive studies on a vehicle lamp, the inventors of the present disclosure have come to recognize that a light quantity of a vehicle lamp may be reduced due to the fastening structure of the substrate, the heat dissipating plate, and the reflector in the conventional vehicle lamp. 
     The present disclosure has been made in consideration of such a situation, and an object thereof is to provide a technology of increasing a light quantity of a vehicle lamp. 
     In order to solve the above-described problem, an aspect of the present disclosure provides a vehicle lamp. The vehicle lamp includes a substrate having a light source mounting surface, a heat dissipating member disposed on a surface of the substrate at a side opposite to the light source mounting surface, a reflector disposed at the light source mounting surface side of the substrate to reflect light emitted from a light source mounted on the light source mounting surface, and a fastening member configured to fix the substrate, the heat dissipating member, and the reflector to each other. The reflector includes a boss portion that protrudes toward the heat dissipating member side and includes a fastening hole for the fastening member. The substrate includes a first opening in an area overlapping with the boss portion in the stacking direction of the reflector, the substrate, and the heat dissipating member. The heat dissipating member is in contact with the substrate to be thermally conductive with the substrate and includes a first portion that includes a second opening in an area overlapping with the boss portion in the stacking direction, a second portion that overlaps with the second opening in the stacking direction and is more spaced apart from the reflector than the first portion to include an insertion hole for the fastening member and a fastening seat surface, and a connecting portion that connects the first portion and the second portion to each other. The boss portion passes through the first opening and the second opening and abuts to the second portion such that the fastening hole and the insertion hole overlap with each other in the stacking direction. According to this aspect, a light quantity of a vehicle lamp may be increased. 
     In the above-described aspect, the heat dissipating member may include a small width portion having a relatively small width and a large width portion having a relatively large width in an area ranging from the end of the connecting portion which is in contact with the first portion to the insertion hole of the second portion. Accordingly, the stress generated by the fastening of the fastening member may be absorbed by the small width portion. 
     According to the present disclosure, a light quantity of a vehicle lamp may be increased. 
     The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view schematically illustrating a structure of a headlamp device including a vehicle lamp according to an exemplary embodiment. 
         FIG. 2  is a view for describing an assembly structure of the vehicle lamp in the exemplary embodiment. 
         FIG. 3A  is a perspective view schematically illustrating a small width portion and a large width portion in a vehicle lamp according to Modification 1.  FIG. 3B  is a perspective view schematically illustrating a small width portion and a large width portion in a vehicle lamp according to Modification 2.  FIG. 3C  is a perspective view schematically illustrating a small width portion and a large width portion in a vehicle lamp according to Modification 3.  FIG. 3D  is a perspective view schematically illustrating a small width portion and a large width portion in a vehicle lamp according to Modification 4. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, preferred exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. Identical or corresponding components, members, and processes in each of the drawings will be denoted by the same symbols, and overlapping descriptions thereof will be appropriately omitted. Further, the exemplary embodiments are not intended to limit the present disclosure thereto, but are merely exemplary. All features described in the exemplary embodiments or combinations thereof may not be essential for the present disclosure. In addition, for example, the terms “first” and “second” used herein or the claims are not intended to refer to any order or importance but are intended to discriminate a component from another component. 
       FIG. 1  is a cross-sectional view schematically illustrating a structure of a headlamp device including a vehicle lamp according to an exemplary embodiment.  FIG. 2  is a view for describing an assembly structure of the vehicle lamp in the exemplary embodiment. In addition, a scale or a shape of each component illustrated in each of the drawings is conveniently set in order to facilitate descriptions thereof and should not be construed as being limited. 
     A lamp unit  100  as a vehicle lamp according to an exemplary embodiment is mounted in, for example, a headlamp device  10 . The headlamp device  10  includes a pair of headlamp units which are disposed at the front left and right sides of a vehicle, respectively. The pair of headlamp units has a substantially identical configuration, except that the structures thereof are bilaterally symmetrical to each other. Thus,  FIG. 1  illustrates a structure of one of the pair of headlamp units as the headlamp device  10 . 
     The headlamp device  10  includes a lamp body  11  and a transparent external cover  12  that covers a front opening of the lamp body  11 . The lamp body  11  and the external cover  12  form a lamp chamber  13 . The lamp unit  100  as a vehicle lamp is accommodated within the lamp chamber  13 . The lamp unit  100  is configured to illuminate at least one of, for example, a high beam light distribution pattern and a low beam light distribution pattern. 
     The lamp unit  100  is supported to the lamp body  11  by a bracket  50 . The bracket  50  is formed of, for example, a resin material. A first tilting member  55  and a second tilting member  57  are attached to the bracket  50 . The first tilting member  55  includes an aiming screw  55   a  attached to the lamp body  11 , a screw connection unit  55   b  provided in the bracket  50  of the first tilting member  55 , and an adjustment unit  55   c  disposed outside the lamp body  11 . One end side of the aiming screw  55   a  is inserted into the screw connection unit  55   b,  and the other end side thereof is connected to the adjustment unit  55   c.  The second tiling member  57  includes a ball joint  57   a  attached to the lamp body  11 , a socket  57   b  that holds the ball of the ball joint  57   a,  and a hole  57   c  provided in the bracket  50  of the second tilting member  57 . The socket  57   b  is inserted into the hole  57   c.  In the present exemplary embodiment, the aiming mechanism is connected to the bracket  50 . However, the exemplary embodiment is not limited particularly to the configuration. For example, the aiming mechanism may be connected directly to the lamp unit  100  without requiring the brackets  50 . 
     When the aiming screw  55   a  is rotated through the adjustment unit  55   c  of the first tiling member  55 , the bracket  50  is tilted with respect to the lamp body  11  around the ball of the ball joint  57   a  of the second tiling member  57  as a fulcrum. In this way, the optical axis of the lamp unit  100  may be adjusted. 
     The lamp unit  100  includes a substrate  110 , a reflector  130 , a heat dissipating member  150 , and a fastening member  170 . The lamp unit  100  of the present exemplary embodiment is a so-called parabola-type lamp unit. 
     The substrate  110  is a substantially plate shaped member that supports a light source  114 . The substrate  110  includes a light source mounting surface  112 , and the light source  114  is mounted on the light source mounting surface  112 . The light source  114  is, for example, a light emitting diode (LED). In the present exemplary embodiment, the main surface of the substrate  110  which faces vertically downward is the light source mounting surface  112 . The light source  114  is mounted on the light source mounting surface  112  such that a light emitting surface thereof faces vertically downward. The light source mounting surface  112  is provided with a wiring pattern (not illustrated) to which the light source  114  is electrically connected. In the present exemplary embodiment, the posture of the lamp unit  100  is set such that the light emitting surface of the light source  114  faces vertically downward. However, the posture of the lamp unit  100  is not limited to this configuration. For example, the posture of the lamp unit  100  may be set such that the normal line of the light emitting surface of the light source  114  is in parallel with the horizontal surface. For example, the lamp unit  100  may take a posture of being rotated 90 degrees around the optical axis from the state illustrated in  FIG. 1  such that the light emitting surface of the light source  114  faces the side of the lamp unit. Alternatively, the posture of the lamp unit  100  may be set such that the light emitting surface of the light source  114  faces vertically upward. The installation angle of the lamp unit  100  may be appropriately selected. 
     In addition, the substrate  100  includes a first opening  116  in an area overlapping with a boss portion  136  to be described later in the stacking direction A of the reflector  130 , the substrate  110 , and the heat dissipating member  150  (in the direction represented by arrow A in  FIGS. 1 and 2 ). 
     The reflector  130  is disposed at the light source mounting surface  112  side of the substrate  110 . The reflector  130  includes a flat-plate-shaped base portion  132  that abuts to the substrate  110 , and a reflecting portion  134  that extends from the end of the base portion  132  at the rear side of the vehicle toward the front side of the vehicle while being curved downward. The base portion  132  includes a light source opening  132   a  in an area overlapping with the light source  114 . The reflecting portion  134  includes a reflecting surface  134   a  that reflects light emitted from the light source  114  mounted on the light source mounting surface  112  toward the front side of the lamp. 
     The reflecting surface  134   a  is formed based on a shape of, for example, a rotating parabolic surface of which the rotating central axis is the optical axis of the reflector  130 . The reflector  130  is disposed such that the optical axis thereof extends in the front-and-rear direction of the vehicle. The light source  114  is disposed within the light source opening  132   a  such that the light emitting surface thereof is substantially opposite to the reflecting surface  134   a.  The mutual positional relationship between the light source  114  and the reflecting surface  134   a  is set such that a focal point of the reflecting surface  134   a  overlaps with the light source  114 . 
     The reflector  130  also includes the boss portion  136 . The boss portion  136  is provided on the surface of the base portion  132  which is in contact with the substrate  110  and protrudes toward the heat dissipating member  150  side. The boss portion  136  includes a fastening hole  136   a  for the fastening member  170 . The reflector  130  is formed by performing an aluminum deposition on an area of, for example, a resin-molded substrate which corresponds to at least the reflecting surface  134   a.    
     The heat dissipating member  150  is formed by, for example, an aluminum plate and has a function to dissipate heat generated from the light source  114 . By providing the heat dissipating member  150 , the dissipation performance of heat from the light source  114  may be improved. The heat dissipating member  150  is disposed on the surface of the substrate  110  at the side opposite to the light source mounting surface  112 . The heat dissipating member  150  includes a first portion  152 , a second portion  154 , and a connecting portion  156 . 
     The first portion  152  has a flat plate shape and is in contact with the substrate  110  to be thermally conductive with the substrate  110 . In the present exemplary embodiment, the first portion  152  and the substrate  110  are in contact with each other through a heat transfer sheet  158  which has an insulating property and flexibility or elasticity. The heat transfer sheet  158  is provided in an area overlapping with at least the light source  114  in the stacking direction A. The heat transfer sheet  158  is interposed between the substrate  110  and the first portion  152  so that the heat transfer between the substrate  110  and the heat dissipating member  150  may be more reliably ensured, thereby further improving the dissipation performance of heat from the light source  114 . The first portion  152  and the substrate  110  may be in direct contact with each other. Without being limited to the heat transfer sheet  158 , a thermal interface material (TIM) such as, for example, a thermal conductive grease or a thermal conductive adhesive may be interposed between the first portion  152  and the substrate  110 . 
     The first portion  152  includes a second opening  152   a  in an area overlapping with the boss portion  136  in the stacking direction A. 
     The second portion  154  is disposed in a position overlapping with the second opening  152   a  in the stacking direction A. The second portion  154  is more spaced apart from the reflector  130  than the first portion  152 . The second portion  154  includes an insertion hole  154   a  for the fastening member  170  and a fastening seat surface  154   b  disposed around the insertion hole  154   a.  The second portion  154  extends in parallel with, for example, the first portion  152 . 
     The connecting portion  156  connects the first portion  152  and the second portion  154  to each other. One end side of the connecting portion  156  is connected to the first portion  152 . Then, the connecting portion  156  extends vertically upward or in a direction separated from the substrate  110  or the reflector  130  from the first portion  152  such that the other end side of the connecting portion  156  is connected to the second portion  154 . 
     The heat dissipating member  150  includes a small width portion T having a relatively small width and a large width portion W having a relatively large width, in an area ranging from an end  156   a  of the connecting portion  156  which is in contact with the first portion  152  to the insertion hole  154   a  of the second portion  154 . The width N of the small width portion T is smaller than the width M of the large width portion W, and the width M of the large width portion W is larger than the width N of the small width portion T. The range of the area where the small width portion T and the large width portion W are provided is, for example, from the end  156   a  to the end of the insertion hole  154  which is closest to the connecting portion  156 . In the present exemplary embodiment, the small width portion T is provided in the area ranging from the end  156   a  of the connecting portion  156  to a midway of the connecting portion  156 , and the rest of the connecting portion  156  and the second portion  154  form the large width portion W. 
     Here, the “width” of the small width portion T and the large width portion W refers to a dimension in a direction orthogonal to the extending direction of the member provided with the small width portion T or the large width portion W. In the present exemplary embodiment, the width of the small width portion T refers to the length of the area of the connecting portion  156  where the small width portion T is provided, in the direction orthogonal to the extending direction of the connecting portion  156 . Further, the width of the large width portion W refers to the length of the area  156   b  in the direction orthogonal to the extending direction of the connecting portion  156 , and the length of the second portion  154  in the direction orthogonal to the extending direction of the second portion  154 . The extending direction of the connecting portion  156  refers to the direction in which, for example, the end  156   a  of the connecting portion  156  and the end thereof which is in contact with the second portion  154  are arranged. The extending direction of the second portion  154  refers to the direction in which, for example, the end of the second portion  154  which is in contact with the connecting portion  156  and the insertion hole  154   a  are arranged. 
     In other words, the connecting portion  156  has a portion in which the opposite sides of the connecting portion  156  become distant from each other stepwise toward the end side of the connecting portion  156  which is in contact with the second portion  154  from the end  156   a  side. In the present exemplary embodiment, the opposite sides become distant from each other single-stepwise, but may become distant from each other multi-stepwise. Further, the distance between the opposite sides may increase continuously. Further, the connecting portion  156  may have a portion in which opposite sides of the connecting portion  156  become close to each other stepwise or continuously toward the end side of the connecting portion  156  which is in contact with the second portion  154  from the end  156   a  side. In this case, the small width portion T is provided in a position spaced apart from the end  156   a.    
     In addition, the area of the cross section of the small width portion T which is orthogonal to the extending direction of the member provided with the small width portion T is smaller than the area of the cross section of the large width portion W which is orthogonal to the extending direction of the member provided with the large width portion W. In addition, for example, the width N of the small width portion T is narrower than the width of the area of the fastening seat surface 1 Mb on which the head of the fastening member  170  contacts. Further, the small width portion T and the large width portion W may adopt various shapes and arrangements as also described in modifications to be described later. 
     The heat dissipating member  150  may be formed by providing a notch along the shapes of the second portion  154  and the connecting portion  156  at a predetermined position of, for example, an aluminum plate and cutting off the internal portion of the notch. The cut-off portion of the aluminum plate becomes the second portion  154  and the connecting portion  156 , and the rest thereof becomes the first portion  152 . 
     The fastening member  170  is configured to fix the substrate  110 , the heat dissipating member  150 , and the reflector  130  to each other. The fastening member  170  is, for example, a screw. As illustrated in  FIG. 2 , the substrate  110  and the heat dissipating member  150  are disposed on the base portion  132  of the reflector  130 . In this case, the boss portion  136 , the first opening  116 , and the second opening  152   a  are positioned so as to overlap with each other in the stacking direction A. Then, the substrate  110  and the heat dissipating member  150  are stacked on the base portion  132 . 
     As a result, as illustrated in  FIG. 1 , the boss portion  136  passes through the first opening  116  and the second opening  152   a  and abuts to the second portion  154  such that the fastening hole  136   a  and the insertion hole  154   a  overlap with each other in the stacking direction A. In this state, the fastening member  170  is inserted into and passes through the insertion hole  154   a  so as to be fastened into the fastening hole  136   a.  When the fastening member  170  is a screw, the fastening member  170  is screw-coupled to the fastening hole  136   a.  The head of the fastening member  170  abuts on the fastening seat surface  154   b.  In this way, the substrate  110 , the reflector  130 , and the heat dissipating member  150  may be fixed to each other. 
     As described above, the lamp unit  100  as the vehicle lamp according to the present exemplary embodiment includes the substrate  110 , the reflector  130 , the heat dissipating member  150 , and the fastening member  170 . The reflector  130  includes the boss portion  136  that protrudes toward the heat dissipating member  150  side and has the fastening hole  136   a.  The substrate  110  includes the first opening  116  through which the boss portion  136  passes. The heat dissipating member  150  includes the first portion  152  that includes the second opening  152   a  through which the boss portion  136  passes, the second portion  154  that is disposed at the upper side than the first portion to include the insertion hole  154   a  and the fastening seat surface  154   b,  and the connecting portion  156  that connects the first portion  152  and the second portion  154  to each other. The boss portion  136  protrudes toward the heat dissipating member  150  side such that the front end thereof abuts to the second portion  154 . In this state, the fastening member  170  is inserted into and passes through the insertion hole  154   a  so that the substrate  110 , the reflector  130 , and the heat dissipating member  150  are fixed to each other. 
     In a conventional structure of fixing a substrate, a heat dissipating member, and a reflector to each other by using a fastening member, a boss portion provided in the reflector protrudes toward a reflecting surface side. The boss portion is required to have a predetermined height in order to secure a depth of a fastening hole into which the fastening member is engaged. Hence, in the conventional structure, the boss portion may overlap with a light path of light emitted from a light source, in particular, a light path in which light reflected on the reflecting surface travels toward the front side of the lamp. In this case, the traveling of the light toward the front side of the lamp is disturbed by the boss portion, thereby reducing a light quantity of the vehicle lamp. 
     The overlapping between the boss portion and the light path of light emitted from the light source may be avoided by spacing the substrate and the reflector apart from each other and disposing the boss portion to protrude toward the substrate side such that the boss portion is accommodated in the space between the substrate and the reflector. However, when the substrate and the reflector are spaced apart from each other, a solid angle of a light flux incident on the reflecting surface of the reflector from a light source is reduced. That is, among light emitted from the light source, a quantity of light that can reach the reflecting surface of the reflector is reduced. As a result, the light quantity of the vehicle lamp is reduced. 
     In the present exemplary embodiment, the boss portion  136  protrudes toward the substrate  110  side and is inserted into and passes through the first opening  116  of the substrate  110  and the second opening  152   a  of the heat dissipating member  150 . Accordingly, since the space for accommodating the boss portion  136  may not be provided between the substrate  110  and the reflector  130 , the substrate  110  and the reflector  130  may be positioned close to each other. Thus, it is possible to avoid that the boss portion  136  and the light path of light emitted from the light source overlap with each other and also avoid that the solid angle of the incident light flux is reduced. As a result, the light quantity of the vehicle lamp may be increased. 
     In addition, the heat dissipating member  150  includes the small width portion T and the large width portion W in the range from the end  156   a  of the connecting portion  156  which is in contact with the first portion  152  to the insertion hole  154   a  of the second portion  154 . As the two areas having different widths are provided, the small width portion T having a relatively small width naturally becomes a fragile portion compared to the large width portion W having a relatively large width. Hence, the small width portion T is deformed by the stress generated when the fastening member  170  is fastened. Accordingly, the small width portion T is able to absorb the stress generated when the fastening member  170  is fastened. Further, since the stress may be absorbed by the small width portion T, it is possible to avoid that the substrate  110  is distorted by the stress generated at the time of the fastening thereby causing a positional deviation of the light source  114 . As a result, it is possible to suppress the accuracy in the formation of a light distribution pattern by the lamp unit  100  from being deteriorated. 
     The present disclosure is not limited to the above-described exemplary embodiment. Further modifications (e.g., various design modifications) may be made to the present disclosure based on the knowledge of a person ordinarily skilled in the art. The scope of the present disclosure also includes exemplary embodiments to which the modifications are applied. An exemplary embodiment which is newly made by a combination of the above-described exemplary embodiment and a modification exhibits an effect of each of the exemplary embodiment and the modification to be combined with each other. 
     In the above-described exemplary embodiment, the small width portion T is provided in a part of the connecting portion  156 , and the large width portion W is provided in the remaining part of the connecting portion  156  and the second portion  154 . However, the dispositions and the shapes of the small width portion T and the large width portion W are not limited to those described in the above-described exemplary embodiment. For example, the small width portion T may be provided in a part of the area ranging from the end of the second portion  154  which is in contact with the connecting portion  156  to the insertion hole  154   a,  and the large width portion W may be provided in the rest of the second portion  154  and the connecting portion  156 . 
     In addition, as the dispositions and the shapes of the small width portion T and the large width portion W, for example, Modifications 1 to 4 may be exemplified as described below. 
     Modification 1 
       FIG. 3A  is a perspective view schematically illustrating a small width portion and a large width portion in a vehicle lamp according to Modification 1. As illustrated in  FIG. 3A , in the heat dissipating member  150  of Modification 1, the small width portion T is provided in the second portion  154 , and the large width portion W is provided in the connecting portion  156 . In Modification 1, the entire second portion  154  constitutes the small width portion T, and the entire connecting portion  156  constitutes the large width portion W. In other words, in the present modification, the distance between the opposite sides changes at the connected portion between the connecting portion  156  and the second portion  154 . In this case as well, the stress generated at the time of the fastening of the fastening member  170  may be absorbed by the small width portion T. Further, the entire connecting portion  156  may constitute the small width portion T, and the entire second portion  154  may constitute the large width portion W. 
     Modification 2 
       FIG. 3B  is a perspective view schematically illustrating a small width portion and a large width portion in a vehicle lamp according to Modification 2. As illustrated in  FIG. 3B , in Modification 2, a small width portion T is formed in the connecting portion  156  by providing an opening  156   c  in the connecting portion  156 . In the present modification, the small width portion T corresponds to a frame portion of the opening  156   c.  Accordingly, the connecting portion  156  includes two small width portions T, and the large width portion W of the insertion hole  154   a  side and the large width portion W of the first portion  152  side are connected to each other by the two small width portions T. In this case as well, the stress generated at the time of the fastening of the fastening member  170  may be absorbed by the small width portions T. In addition, the small width portion T may be formed by providing an opening in the area ranging from the end of the second portion  154  which is in contact with the connecting portion  156  to the insertion hole  154   a.  In addition, the opening  156   c  provided in the connecting portion  156  and the opening provided in the second portion  154  may be continuous to each other so as to become one opening. That is, an opening may be provided in the area where the connecting portion  156  and the second portion  154  are in contact with each other. 
     Modification 3 
       FIG. 3C  is a perspective view schematically illustrating a small width portion and a large width portion in a vehicle lamp according to Modification 3. As illustrated in  FIG. 3C , in Modification 3, a small width portion T is formed in the second portion  154  by providing a notch  154   c  in the second portion  154 . In the present modification, the small width portion T refers to a locally constricted portion which has a small width in the second portion  154 . In other words, the second portion  154  of the present modification has an area in which the opposite sides thereof become close to each other stepwise or continuously toward the insertion hole  154   a  side from the end side of the second portion  154  which is in contact with the connecting portion  156 , and then, become distant from each other stepwise or continuously. In this case as well, the stress generated at the time of the fastening of the fastening member  170  may be absorbed by the small width portions T. 
     Modification 4 
       FIG. 3D  is a perspective view schematically illustrating a small width portion and a large width portion in a vehicle lamp according to Modification 4. As illustrated in  FIG. 3D , in Modification 4, a small width portion T is formed in the connecting portion  156  by providing a notch  156   d  in the connecting portion  156 . In the present modification, the small width portion T refers to a locally constricted portion which has a small width in the connecting portion  156 . In other words, the connecting portion  156  of the present modification has an area in which the opposite sides thereof become close to each other stepwise or continuously toward the end side of the connecting portion  156  which is in contact with the second portion  154  from the end  156   a  side, and then, become distant from each other stepwise or continuously. In this case as well, the stress generated at the time of the fastening of the fastening member  170  may be absorbed by the small width portions T. In addition, the connecting portion  156  of the present modification includes a portion that extends in parallel with the first portion  152  from the second opening  152   a,  and a portion that extends from the front end of the portion extending in parallel with the first portion  152  to be spaced apart from the first portion  152  and connected to the second portion  154 . 
     Other Modifications 
     In the above-described exemplary embodiment, an LED is exemplified as the light source  114 . However, the light source  114  is not limited to the LED, but may be, for example, a semiconductor laser or a valve lamp. In addition, a parabola-type lamp unit is exemplified as the lamp unit  100 . However, the lamp unit  100  may be a projector-type lamp unit or a lamp unit of a polarized electron source (PES) optical system. 
     From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the following claims.