Abstract:
A projector includes a light source portion; and an optical scanning portion that scans light from the light source portion, wherein the light source portion comprises a first holder that holds a light source, and a second holder that holds an optical portion through which light from the light source is emitted, and the first holder and the second holder are arranged in that order from a light emitting direction.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to a projector and head up display device, and more particularly to a projector and head up display device provided with a light source holding portion and an optical system holding portion. 
       BACKGROUND ART 
       [0002]    A conventional optical path adjusting device for a magneto-optical disk device provided with an optical system holding portion and a light source holding portion is known (For example, refer to Patent Document 1). 
         [0003]    In Patent Document 1, an optical path adjusting device for a magneto-optical disk device is disclosed that comprises a semiconductor laser, a first fixing member (light source holding portion) for holding the semiconductor laser, a collimator lens, and a second fixing member (optical system holding portion) for holding the collimator lens. In this optical path adjusting device, the first fixing member and the second fixing member are fixed by a bolt with the first fixing member positioned in relation to the second fixing member (position adjusting for optical path adjusting). 
       PRIOR ART DOCUMENTS 
     Patent Documents 
       [0004]    [Patent Document 1] Japanese Unexamined Patent Application Publication No. H5-323166 
         [0005]    However, with the optical path adjusting device for a magneto-optical disk device disclosed in Patent Document 1, position displacement of the first fixing member and the second fixing member may occur due to fastening torque of a bolt when fixing the first fixing member and the second fixing member with a bolt. Furthermore, when the first fixing member and the second fixing member are fixed with a bolt, the fixation may become loose due to vibrations, shocks, temperature changes, and the like, possibly causing the position displacement of the first fixing member and the second fixing member. 
         [0006]    Moreover, when the fixing members are fixed with an adhesive, position displacement may occur when curing is complete by the contraction and expansion of the adhesive because curing begins from when the adhesive is applied after positioning. Furthermore, position displacement may occur due to temperature change and the like. Therefore, the position displacement of the first fixing member and the second fixing member may occur, similarly to the case of fixing with a bolt. 
         [0007]    One or more embodiments of this invention provide a projector and head up display device that can fix a high-precision positioning of a light source holding portion and an optical system holding portion and can maintain the high-precision positioning. 
       SUMMARY OF THE INVENTION 
       [0008]    The projector according to examples of a first aspect of this invention comprises a light source unit (or “light source portion”) and an optical scanning portion that scans light from the light source unit, wherein the light source unit includes a light source holding portion (or “first holder”) for holding a light source and an optical system holding portion (or “second holder”) for holding an optical system (or “optical portion”) where light from the light source is emitted, the light source holding portion and the optical system holding portion being laser welded together. 
         [0009]    In accordance with one or more embodiments, the light source holding portion and the optical system holding portion are arranged, in that order, when viewed from a light emitting direction. 
         [0010]    With the projector according to examples of the first aspect of the present invention, a light source holding portion and an optical system holding portion are laser welded together as described above. As a result, for example, fastening torque does not occur, different than when the light source holding portion and the optical system holding portion are fixed by a bolt or the like. As a result, the light source holding portion and the optical system holding portion can be positioned and fixed with high-precision because position displacement when fixing the light source holding portion and the optical system holding portion can be suppressed. Furthermore, because the light source holding portion and the optical system holding portion can be integrated by laser welding, the occurrence of position displacement of the light source holding portion and the optical system holding portions due to vibrating, shock, temperature changes, and the like can be suppressed with the light source holding portion and the optical system holding portion fixed by laser welding. As a result, the high-precision positioning of the light source holding portion and the optical system holding portion can be maintained with the light source holding portion and the optical system holding portion fixed by laser welding. As a result, it is possible to fix the light source holding portion and the optical system holding portion with a high-precision positioning and the high-precision positioning can be maintained. 
         [0011]    With the projector according to examples of the first aspect described above, the light source holding portion and the optical system holding portion may be laser welded in a plurality of positions sandwiching the light source. If configured in this manner, it is possible to more strongly fix the light source holding portion and the optical system holding portion compared to fixing the light source holding portion and the optical system holding portion by laser welding in only one location. 
         [0012]    With the projector according to examples of the first aspect described above, the light source holding portion and the optical system holding portion may be made of light transmitting resin, and the other of the light source holding portion and the optical system holding portion to be made of light absorbing resin. If configured in this manner, the light source holding portion and the optical system holding portion can be easily fixed using laser welding. 
         [0013]    In this case, the light source holding portion may be made of light transmitting resin, and the optical system holding portion may be made of light absorbing resin. If configured in this manner, laser light used for laser welding can be irradiated from the light source holding portion side (light transmitting resin side) opposite the optical system holding portion with many ordinary various members (for example, optical members such as prisms following an optical system) provided. As a result, the light source holding portion and the optical system holding portion can be fixed by laser welding. 
         [0014]    In a configuration where the light source holding portion is made of light transmitting resin and the optical system holding portion is made of light absorbing resin, the light source holding portion made of light transmitting resin may have a protruding portion protruding from a side opposite the optical system holding portion in a position corresponding to the region to be laser welded. If configured in this manner, a transparent plate and the protruding portion of the light source holding portion protruding from the side opposite the optical system holding portion can be easily adhered when irradiating laser light used for laser welding with the light source holding portion made of light transmitting resin being pressed by the transparent plate (for example, a glass plate) that transmits laser light from the side opposite the optical system holding portion. As a result, air becoming interposed (a layer of air) between the transparent plate and the protruding portion of the light source holding portion can be easily suppressed. Therefore, it is possible to suppress fixing by laser welding not being sufficiently performed due to the light condensing position (focus point) of the laser light being displaced by air (a layer of air). 
         [0015]    With the projector according to one or more embodiments of the first example described above, the light source unit may additionally include a housing for holding the optical system holding portion with the light source holding portion and the optical system holding portion laser welded, and for the optical system holding portion and the housing to be fastened by a fastening member. If configured in this manner, fixing can be done by laser welding with high-precision positioning with the light source holding portion and the optical system holding portion that require a high-precision positioning because they are arranged relatively closely, and a fixing configuration by a fastening member that can easily perform a fixing operation can be achieved with the optical system holding portion and the housing that do not require a relatively high-precision positioning (where error is relatively allowable). Furthermore, the housing and the optical system holding portion are both made of light absorbing resin, and the housing and the optical system holding portion can be easily fixed by a fastening member even when laser welding is difficult. 
         [0016]    With the projector according to one or more embodiments of the first example described above, the light source unit may additionally include a housing for holding the optical system holding portion with the light source holding portion and the optical system holding portion laser welded, and for the optical system holding portion and the housing to be laser welded together. If configured in this manner, in addition to the light source holding portion and the optical system holding portion, a fixing can also be performed with a high-precision positioning on the optical system holding portion and the housing. 
         [0017]    The head up display device according to examples of the second aspect of this invention comprises a light source unit and an optical scanning portion that scans light from the light source unit corresponding to a virtual image that a user views, and the light source unit includes a light source holding portion for holding a light source and an optical system holding portion for holding an optical system where light from the light source is emitted, the light source holding portion and the optical system holding portion being laser welded together. 
         [0018]    With the head up display device according to examples of the second aspect of this invention, a light source holding portion and an optical system holding portion are laser welded together as described above. As a result, it is possible to fix the light source holding portion and the optical system holding portion with a high-precision positioning and maintain the high-precision positioning even with the head up display device according to examples of the second aspect. Furthermore, with the head up display device where high brightness is required, it is common that the light source held by the light source holding portion and the optical system held by the optical system holding portion to be arranged closer than an ordinary projector. When the light source and the optical system are arranged close, fixing with a higher precision positioning is required because the effects of position displacement are great. Therefore, it is extremely practically effective in the head up display device to be able to fix the light source holding portion and the optical system holding portion with a high-precision positioning and to maintain the high-precision positioning. 
         [0019]    According to one or more embodiments of the present invention, a projector and head up display device can be provided that can fix a high-precision positioning of a light source holding portion and an optical system holding portion and can maintain the high-precision positioning. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a diagram illustrating the head up display device according to one or more embodiments of the first through the third examples of the present invention being mounted on an automobile. 
           [0021]      FIG. 2  is a block diagram illustrating the overall configuration of the head up display device according to one or more embodiments of the first through the third examples of the present invention. 
           [0022]      FIG. 3  is a perspective view illustrating the light source unit of the head up display device according to one or more embodiments of the first and the second examples of the present invention. 
           [0023]      FIG. 4  is a perspective view of the light source holding portion and optical system holding portion of the head up display device according to one or more embodiments of the first example of the present invention, viewed from the light source holding portion side. 
           [0024]      FIG. 5  is a perspective view of the light source holding portion and optical system holding portion of the head up display device according to one or more embodiments of the first example of the present invention, viewed from the optical system holding portion side. 
           [0025]      FIG. 6  is a perspective view of the light source holding portion and optical system holding portion of the head up display device according to one or more embodiments of the first example of the present invention, viewed from the optical axis direction. 
           [0026]      FIG. 7  is a cross-sectional view along the 500-500 line in  FIG. 6 . 
           [0027]      FIG. 8  is a schematic diagram for describing a fixation of the light source holding portion and the optical system holding portion of the head up display device of one or more embodiments of the present invention by laser welding. 
           [0028]      FIG. 9  is a perspective view for describing a fixation of the optical system holding portion and housing of the head up display device according to one or more embodiments of the first example of the present invention by a screw member. 
           [0029]      FIG. 10  is a diagram for describing a fixation of the optical system holding portion and housing of the head up display device according to one or more embodiments of the second example of the present invention by laser welding. 
           [0030]      FIG. 11  is a perspective view for describing a fixation of the optical system holding portion and housing of the head up display device according to one or more embodiments of the first example of the present invention by a biasing member. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0031]    Specific embodiments of the present invention will be described below using the drawings. 
       First Example 
       [0032]    First, the configuration of a head up display device  100  according to one or more embodiments of the first example of the present invention will be described with reference to  FIG. 1 . The head up display device  100  is one example of a “projector” of the present invention. 
         [0033]    The head up display device (disclosed below as HUD device)  100  according to one or more embodiments of the first example of the present invention is configured to mount on a transportation apparatus such as an automobile  600 , as illustrated in  FIG. 1 . Moreover, the HUD device  100  is configured to project (irradiate) light forming a projection image on a screen  601  such as a front glass or a combiner not illustrated in the diagrams. The light forming the projection image projected on the screen  601  is then reflected on the screen  601 , and viewed by the user. At this time, the projection image is viewed by the user as a virtual image in a position in front of the user on the screen  601 . This HUD device  100  is configured to project information relating to car navigation, the speed of the automobile  600 , information of various notifications, and the like as a projection image. 
         [0034]    Furthermore, the HUD device  100  comprises a light source unit  1 , an optical scanning portion  2 , and a display control portion  3 , as illustrated in  FIG. 2 . 
         [0035]    Here, in one or more embodiments of the first example, the light source unit  1  includes three (blue (B), red (R), and green (G)) laser diodes  10  ( 10   a ,  10   b , and  10   c ) and three light source holding portions  20  for holding each of the three laser diodes  10 . Furthermore, the light source unit  1  includes three collimator lenses  30  that emit laser light from each of the three laser diodes  10 , and three optical system holding portions  40  for holding each of the three collimator lenses  30 . In this HUD device  100 , the light source holding portion  20  and the optical system holding portion  40  are laser welded together. The laser diode  10  and the collimator lens  30  are each one example of a “light source” and “optical system” of the present invention. More generally, the “optical system” may comprise a collimator lens. Details regarding the fixation of the light source holding portion  20  for holding the laser diode  10  and the optical system holding portion  40  for holding the collimator lens  30  by laser welding will be described later. 
         [0036]    Moreover, as illustrated in  FIG. 2  and  FIG. 3 , the light source unit  1  includes three prisms  51   a ,  51   b , and  51   c  for providing an optical axis for each laser light by combining three (blue (B), red (R), and green (G)) laser lights, a beam shaping prism  52  for shaping a spot shape of the laser light that has passed through the prisms  51   a ,  51   b , and  51   c , and a condenser lens  53  for condensing the laser light that has passed through the beam shaping prism  52 . 
         [0037]    Furthermore, the light source unit  1  includes a housing  60  for holding various members as illustrated in  FIG. 3 . The housing  60  is configured to hold the optical system holding portion  40  with the light source holding portion  20  holding the laser diode  10  and the optical system holding portion  40  holding the collimator lens  30  laser welded together. 
         [0038]    Specifically, the in housing  60 , the members (light source holding portion  20 , collimator lens  30 , and optical system holding portion  40 ) corresponding to the three (blue (B), red (R), and green (G)) laser diodes  10   a  to  10   c  are each held on a surface of a Z 2  direction side, a surface of an X 1  direction side, and a surface of an X 2  direction side. Moreover, the three prisms  51   a  to  51   c  and a beam shaping prism  52  are provided inside the housing  60 . 
         [0039]    In the light source unit  1 , the laser diode  10   a  is configured to irradiate blue laser light to the optical scanning portion  2  by passing through the three prisms  51   a ,  51   b , and  51   c , the beam shaping prism  52 , and a condenser lens  53 . Moreover, the laser diode  10   b  is configured to irradiate red laser light to the optical scanning portion  2  by passing through the prisms  51   b , and  51   c , the beam shaping prism  52 , and the condenser lens  53 . Furthermore, the laser diode  10   c  is configured to irradiate green laser light to the optical scanning portion  2  by passing through the prism  51   c , the beam shaping prism  52 , and the condenser lens  53 . In other words, the laser light emitted from the three laser diodes  10   a  to  10   c  are emitted from an emitting opening  60   a  of the housing  60  toward the optical scanning portion  2 , taking a light path shown by a dashed line. The condenser lens  53  is not illustrated in  FIG. 3 . 
         [0040]    The optical scanning portion  2  includes a horizontal optical scanning portion  2   a  for scanning laser light from the laser diode  10  in a horizontal scanning direction and a vertical optical scanning portion  2   b  for scanning laser light from the laser diode  10  in a vertical scanning direction. The horizontal optical scanning portion  2   a  and the vertical optical scanning portion  2   b  are each configured by a micro electro mechanical system (MEMS) mirror. 
         [0041]    In the optical scanning portion  2 , the horizontal optical scanning portion  2   a  is configured to scan in the horizontal scanning direction with respect to the screen  601  of the automobile  600  (refer to  FIG. 1 ) via the vertical optical scanning portion  2   b  by reflecting the laser light from the laser diode  10 . Furthermore, the vertical optical scanning portion  2   b  is configured to scan in the vertical scanning direction with respect to the screen  601  of the automobile  600  by reflecting again the laser light reflected in the horizontal optical scanning portion  2   a . In this manner, the optical scanning portion  2  is configured to scan laser light from the laser diode  10  (in other words, light that forms the projection image) in the horizontal scanning direction and the vertical scanning direction with respect to the screen  601 . As a result, the light that forms the projection image is projected (irradiated) to the screen  601 . 
         [0042]    The display control portion  3  is configured to control the projection of the projection image based on a video signal input from the exterior. Specifically, the display control portion  3  is configured to control the irradiation of laser light by the laser diode  10  ( 10   a ,  10   b , and  10   c ) as well as control the driving of the optical scanning portion  2  ( 2   a  and  2   b ) based on the video signal input from the exterior. As a result, the display control portion  3  is configured to control the optical scanning portion  2  and the laser diode  10  and performs a control that projects the projection image to the screen  601 . 
         [0043]    Next, a configuration of the laser diode  10 , the light source holding portion  20 , the collimator lens  30 , and the optical system holding portion  40  will be described in detail with reference to  FIGS. 3 to 9 . Three of each of the laser diode  10 , the light source holding portion  20 , the collimator lens  30 , and the optical system holding portion  40  are provided, and all are substantially the same with the exception of the color of the laser light emitted from the laser diodes  10  being different, and therefore a description is given with a configuration corresponding to the laser diode  10   a  (disclosed below as simply laser diode  10 ) provided on the surface of the Z 1  direction side of the housing  60  as an example with reference to  FIGS. 4 to 8 . 
         [0044]    The laser diode  10  has a light emitting portion  11 , a stem  12 , and three terminal portions  13  as illustrated in  FIGS. 4 ,  6 , and  7 . The light emitting portion  11 , the stem  12 , and the three terminal portions  13  are all made of metal. 
         [0045]    The light emitting portion  11  is formed in a column shape that extends in the optical axis direction (Z direction). Furthermore, a semiconductor laser element or the like is provided in the interior of the light emitting portion  11 . The step  12  is configured to be formed in a column shape that extends in the optical axis direction (Z direction) with a diameter less than the light emitting portion  11 , and to support the light emitting portion  11 . The three terminal portions  13  are configured formed in a column shape extending from the stem  12  in a direction towards a side opposite to the light emitting portion  11 , and so that electrical power from the power source is supplied via a wiring portion (for example, flexible print substrate) or the like not illustrated in the diagrams. With the laser diode  10 , the laser light from the light emitting portion  11  is emitted by the electrical power from the power source being supplied to the terminal portion  13 . 
         [0046]    Here, in one or more embodiments of the first example, the light source holding portion  20  has a main body portion  21 , and two welding fixing portions  22  as illustrated in  FIGS. 4 ,  6 , and  7 . Furthermore, the light source holding portion  20  is made of light transmitting resin (here, polyphenylene sulfide (PPS) resin). Here, light transmitting refers to the characteristics of transmitting around 15% or more, or 20% or more of laser light of a prescribed wavelength used for laser welding (for example, around 800 nm to around 1100 nm). 
         [0047]    The main body portion  21  is formed in a substantially rectangular shape from the optical axis direction (Z direction). Furthermore, an opening portion  21   a  for holding the laser diode  10  in the center of the substantially rectangular shape is provided on the main body portion  21 . The opening portion  21   a  is formed in a substantially circular shape slightly larger than the diameter of the stem  12  of the laser diode  10  when viewed from the optical axis direction, and has three fitting members  21   b  provided in a prescribed angle interval (about 120 degree intervals) on the inner peripheral edge of the substantially circular shape. Furthermore, a rotational positioning portion  21   c  is provided in addition to the three fitting portions  21   b  on the inner peripheral edge of the opening portion  21   a  with a substantially circular shape. The three fitting portions  21   b  and the rotational positioning portion  21   c  are each formed so as to protrude from the inner side direction (direction towards the center of the circle) of the opening portion  21   a . The main body portion  21  is configured to hold the laser diode  10  by fitting with pressure the fitting portion  21   b  with the stem  12  of the laser diode  10  positioned in the rotational direction with the optical axis direction as the axis by the rotational positioning portion  21   c.    
         [0048]    Each of the two welding fixing portions  22  are formed in a substantially rectangular shape when viewed from the optical axis direction (Z direction). Moreover, the two welding fixing portions  22  are provided in a position that does not overlap the laser diode  10  and are provided in a position of point symmetry sandwiching the laser diode  10  when viewed from the optical axis direction (Z direction). Moreover, the two welding fixing portions  22  are both formed with the thickness in the Z direction being sufficiently smaller than the main body portion  21 . This is because while a prescribed thickness is necessary for holding the laser diode  10 , it is also necessary for the welding fixing portion  22  to be configured so that laser light transmits easily by making the thickness smaller to an extent so that laser light for laser welding transmits. The thickness, in the optical axis direction (Z), of the welding fixing portions  22  (laser welding region) of the light source holding portion  20  may be 0.2 to 10 mm. 
         [0049]    Furthermore on each of the two welding fixing portions  22 , a protruding portion  22   a  protruding from the side opposite (Z 2  direction) of the optical system holding portion  40 , the protruding portion  22   a  being formed in a substantially columnar shape protruding towards the Z 2  direction from the welding fixing portion  22 , and an edge surface  22   b  of the Z 2  direction side of the substantial column is formed substantially flat. Furthermore, the substantially columnar protruding portion  22   a  is formed with the diameter thereof to be sufficiently larger than the spot diameter of the laser light for laser welding. The protruding portion  22   a  is formed so as to function as an eject pin (E/P) when resin material is released from the mold. As a result, it is possible for the shape of the light source holding portion  20  becoming complicated to be suppressed when compared to a case where E/P are provided other than the protruding portion  22   a.    
         [0050]    The light source holding portion  20  is laser welded with the optical system holding portion  40  on a back surface (surface of the Z 2  direction side) corresponding to the protruding portion  22   a  of the two welding fixing portions  22 . In  FIG. 6 , the location where laser welding is performed (laser welding region) is schematically illustrated by hatching to understand easier. 
         [0051]    The optical system holding portion  40  comprises a base portion  41  and an optical system holding member  42  removable from the base portion  41 , as illustrated in  FIGS. 3 to 7 . As illustrated in  FIG. 7 , the collimator lens  30  is held in the interior of the optical system holding member  42 . Further, both the base portion  41  and the optical system holding member  42  are made of resin. 
         [0052]    Furthermore, the base portion  41  is made of light absorbing resin (here, polyphenylene sulfide (PPS) resin). In other words, the base portion  41  is formed by the same resin material (PPS) as the light source holding portion  20 . Here, light absorbency refers to the characteristics of substantially absorbing laser light (not substantially transmitting) of a prescribed wavelength used for laser welding (for example, around 800 nm to around 1100 nm). For example, a method for adjusting the transmittance (absorbency) of the laser light for welding by adjusting the ratio that an absorbing pigment such as a pigment or a dye is distributed to the resin may be used as the method for forming the light transmitting resin and the light absorbing resin by a common resin material. 
         [0053]    Furthermore, the base portion  41  is formed in a substantially rectangular shape from the optical axis direction (Z direction). Moreover, an opening  41   a  that is penetrated by the light emitting portion  11  of the laser diode  10  is provided in the center of the substantial rectangle on the base portion  41 . Furthermore, two penetration holes  41   b  are provided on the base portion  41 , in a position that does not overlap the two welding fixing portions  22  of the light source holding portions  20  from the optical axis direction. The two penetration holes  41   b  are provided so that a screw member  71  illustrated in  FIG. 9  is penetrating, and are each arranged in a position of point symmetry sandwiching the laser diode  10 . The optical system holding portion  40  is configured to fix to the housing  60  by fastening the base portion  41  in two places on the housing  60  by the screw member  71 . The screw member  71  is one example of a “fastening member” of the present invention. 
         [0054]    Furthermore, a pedestal portion  41   c  for arranging the optical system holding member  42  is provided on the side opposite of the light source holding portions  20 , and two pressing portions  41   d  are provided on both sides of the X direction of the pedestal portion  41   c  in the base portion  41 . 
         [0055]    The optical system holding member  42  is configured to be arranged on the pedestal portion  41   c  with the collimator lenses  30  held in the interior. Furthermore, a receiving portion  42   a  that engages with the pressing portions  41   d  of the base portion  41  is provided on both sides in the X direction on the optical system holding member  42 . The optical system holding member  42  is installed to the base portion  41  by the receiving portion  42   a  being pressed in a Y 2  direction by the pressing portions  41   d  arranged on the pedestal portion  41   c  as illustrated in  FIG. 5 . The optical system holding member  42  is able to slide in the optical axis direction (Z direction) on the pedestal portion  41   c  with the receiving portion  42   a  being pressed in the Y 2  direction by the pressing portions  41   d . In this state, the optical system holding member  42  is fixed to the pedestal portion  41   c  by an adhesive after the positioning (position adjustment) of laser diodes  11  in the optical axis direction. 
         [0056]    Next, the fixing by laser welding of the light source holding portion  20  and the optical system holding portion  40  will be described with reference to  FIGS. 7 and 8 . Afterward, the fixing of the optical system holding portion  40  and the housing  60  by the screw member  71  will be described with reference to  FIG. 9 . 
         [0057]    First, as illustrated in  FIG. 7 , the positioning of the laser diode  10  held by the light source holding portion  20  and the collimator lens  30  held by the optical system holding portion  40  (position adjustment) is performed. Specifically, the optical system holding member  42  of the optical system holding portion  40  is slid in the optical axis direction (Z direction) and the positioning of the collimator lens  30  and the laser diode  10  in the optical axis direction is performed. Then, by moving in the XY plane with the light source holding portion  20  pressed to the base portion  41  of the optical system holding portion  40 , the positioning in the XY plane of the collimator lens  30  and the laser diode  10  is performed. 
         [0058]    Then, after the relative position of the collimator lens  30  and the laser diode  10  has been determined, the optical system holding member  42  and the base portion  41  are fixed by an adhesive, and the light source holding portion  20  and the optical system holding portion  40  are fixed by laser welding. 
         [0059]    Specifically, as illustrated in  FIG. 8 , laser welding is performed in the light source unit  1  with the light source holding portion  20  pressed to the Z 1  direction side (in other words, the optical system holding portion  40  side) by a glass plate  80  that transmits laser light for welding of a prescribed wavelength (for example, around 800 nm to around 1100 nm) for welding. More specifically, laser welding is performed in the light source unit  1  with the glass plate  80  pressed to the edge surface  22   b  of the protruding portion  22   a  of the light source holding portion  20 . 
         [0060]    When laser welding is being performed, the laser light for welding is irradiated from the light source holding portion  20  side (Z 2  direction side) to the protruding portion  22   a  of the light source holding portion  20 . At this time, the laser light for welding is irradiated to focus on the welding region of the boundary surface of the light source holding portion  20  and the optical system holding portion  40 . Then, the laser light for welding transmits through the transparent glass plate  80  and the protruding portion  22   a  of the light source holding portion  20  made of light transmitting resin, and is absorbed by the optical system holding portion  40  made of light absorbing resin. As a result, as illustrated in  FIG. 8 , the light source holding portion  20  made of light transmitting resin and the optical system holding portion  40  made of light absorbing resin are both fused in the welding region of the boundary surface of the light source holding portion  20  and the optical system holding portion  40 . As a result, the light source holding portion  20  and the optical system holding portion  40  are welded. The laser welding is performed on both of the protruding portions  22   a  of the two welding fixing portions  22 . 
         [0061]    The positioning (position adjustment) of the laser diode  10  and the housing  60  is performed with the light source holding portion  20  and the optical system holding portion  40  laser welded, so that the optical axis of the design and the optical axis of the laser diode  10  conform to each other, as illustrated in  FIG. 9 . Specifically, the positioning (position adjustment) of the laser diode  10  and the housing  60  is performed by moving the optical system holding portion  40  on a plane parallel to the side surface of the housing  60  with the optical system holding portion  40  pressed to the side surface of the housing  60 . Then, after determining the relative position of the laser diode  10  and the housing  60 , the optical system holding portion  40  is fixed (fastened) to the housing  60  by the two screw members  71 . 
         [0062]    The following effects can be achieved in one or more embodiments of the first example. 
         [0063]    In one or more embodiments of the first example, the light source holding portion  20  and the optical system holding portion  40  are laser welded together, as described above. As a result, for example, fastening torque does not occur because the light source holding portion  20  and the optical system holding portion  40  are fixed by laser welding, different than when the light source holding portion  20  and the optical system holding portion  40  are fixed by a bolt or the like. As a result, the light source holding portion  20  and the optical system holding portion  40  can be positioned and fixed with high-precision because position displacement when fixing the light source holding portion  20  and the optical system holding portion  40  can be suppressed. Furthermore, because the light source holding portion  20  and the optical system holding portion  40  can be integrated by laser welding, the occurrence of position displacement of the light source holding portion  20  and the optical system holding portion  40  due to vibrating, shock, temperature change, and the like can be suppressed with the light source holding portion  20  and the optical system holding portion  40  fixed by laser welding. As a result, the high-precision positioning of the light source holding portion  20  and the optical system holding portion  40  can be maintained with the light source holding portion  20  and the optical system holding portion  40  fixed by laser welding. As a result, it is possible to fix the light source holding portion  20  and the optical system holding portion  40  with high-precision positioning and the high-precision positioning can be maintained. Therefore, the brightness and image quality of the projection image projected on the screen  601  of the automobile  600  reducing due to position displacement of the light source holding portion  20  and the optical holding portion  40  occurring can be suppressed by the head up display device  100 . 
         [0064]    Furthermore, in the head up display device  100  used where outside light (environmental light) has significant effect such as the screen  601  of the automobile  600 , high brightness is especially required. In the head up display device  100  where high brightness is required, the laser diode  10  held by the light source holding portion  20  and the collimator lens  30  held by the optical system holding portion  40  are arranged closer than an ordinary projector, as illustrated in  FIG. 7 . When the laser diode  10  and the collimator lens  30  are arranged close, fixing with a higher precision positioning is required because the effects of position displacement are great. Therefore, it is extremely practically effective in the head up display device  100  to be able to fix the light source holding portion  20  and the optical system holding portion  40  with high-precision positioning and to maintain the high-precision positioning. 
         [0065]    Furthermore, in one or more embodiments of the first example, the light source holding portion  20  and the optical system holding portion  40  are laser welded together in a plurality of positions that sandwich the laser diode  10  (in other words, positions that correspond to the two welding fixing portions  22 ), as described above. As a result, it is possible to more strongly fix the light source holding portion  20  and the optical system holding portion  40  compared to fixing the light source holding portion  20  and the optical system holding portion  40  by laser welding in only one location. 
         [0066]    Moreover, in one or more embodiments of the first example, the light source holding portion  20  is made of light transmitting resin, and the optical system holding portion  40  is made of light absorbing resin as described above. As a result, the light source holding portion  20  and the optical system holding portion  40  can be easily fixed using laser welding. 
         [0067]    Furthermore, because the light source holding portion  20  is made of light transmitting resin and the optical system holding portion  40  is made of light absorbing resin, laser light used for laser welding can be irradiated from the light source holding portion  20  side (in other words, light transmitting resin side) opposite the optical system holding portion  40  with many of various members (optical members such as the prisms  51   a  to  51   c  following the collimator lenses  30 ) provided. As a result, the light source holding portion  20  and the optical system holding portion  40  can be fixed by laser welding. 
         [0068]    Furthermore, in one or more embodiments of the first example, the light source holding portion  20  made of light transmitting resin has a protruding portion  22   a  protruding from the side opposite the optical system holding portion  40  in a position corresponding to the region to be laser welded (in other words, the position of the welding fixing portion  22 ), as described above. As a result, the glass plate  80  and the protruding portion  22   a  of the light source holding portion  20  protruding from the side opposite the optical system holding portion  40  can be easily adhered when irradiating laser light used for laser welding with the light source holding portion  20  made of light transmitting resin being pressed by the glass plate  80  that transmits laser light from the side opposite the optical system holding portion  40 . As a result, air becoming interposed (a layer of air) between the glass plate  80  and the protruding portion  22   a  of the light source holding portion  20  can be easily suppressed. Therefore, it is possible to suppress fixing by laser welding not being sufficiently performed due to the light condensing position (focus point) of the laser light being displaced by air (a layer of air). 
         [0069]    Moreover, in one or more examples of the present invention, the optical system holding portion  40  and the housing  60  are fastened by the screw member  17  as described above. As a result, fixing can be done by laser welding with high-precision positioning with the light source holding portion  20  and the optical system holding portion  40  that require high-precision positioning because they are arranged relatively closely, and an easy fixing configuration with the screw member  71  can be achieved with the optical system holding portion  40  and the housing  60  that do not require relatively high-precision positioning (where error is relatively allowable). 
       Second Example 
       [0070]    Next, one or more embodiments of the second example will be described with reference to  FIGS. 1 to 3  and  10 . In one or more embodiments of this second example, an example will be described where an optical system holding portion and a housing are fixed by laser welding, different from one or more embodiments of the first example where an optical system holding portion and a housing are fixed by a screw member. Configurations that are the same or substantially similar as those in one or more embodiments of the first example will be shown with the same numerals and descriptions thereof are omitted. 
         [0071]    A head up display device  200  according to one or more embodiments of the second example of the present invention (refer to  FIG. 1 ) comprises a light source unit  101  as illustrated in  FIGS. 2 and 3 . The light source unit  101  includes an optical system holding portion  140  and a housing  160  made of light absorbing resin. The head up display device  200  is one example of a “projector” of the present invention. 
         [0072]    Here, in one or more embodiments of the second example, the optical system holding portion  140  comprises a base portion  141  as illustrated in  FIG. 10 . Two welding fixing portions  141   e  made of light transmitting resin are provided on the base portion  141 . Moreover, the two welding fixing portions  141   e  are both formed in a substantially circular shape when viewed from the optical axis direction, and each is formed in a position of point symmetry sandwiching the laser diode  10 . With the base portion  141 , a portion of the welding mixing portion  141   e  is formed by light transmitting resin, and the other main portion is formed by light absorbing resin. In other words, the base portion  141  is formed by a two color mold of light transmitting resin and light absorbing resin. In  FIG. 10 , the location where laser welding is performed (laser welding region) is schematically illustrated by hatching to understand easier. 
         [0073]    Furthermore, in one or more embodiments of the second example, the light source holding portion  20  and the optical system holding portion  140  are laser welded on the protruding portion  22   a  of the two welding fixing portions  22  of the light source holding portion  20 , and the optical system holding portion  140  and the housing  160  are laser welded on the two welding fixing portions  141   e  of the optical system holding portion  140 . The optical system holding portion  140  can laser weld in four positions illustrated in  FIG. 10  because while the back surface side of the protruding portion  22   a  of the welding fixing portion  22  of the light source holding portion  20  is made of light absorbing resin, the welding fixing portions  141   e  are made of light transmitting resin. 
         [0074]    The other configurations of one or more embodiments of the second example may be the same as those of the first example. 
         [0075]    The following effects can be achieved in one or more embodiments of the second example. 
         [0076]    In one or more embodiments of the second example, the light source holding portion  20  and the optical system holding portion  140  are laser welded together, as described above. As a result, it is possible to fix the light source holding portion  20  and the optical system holding portion  140  with high-precision positioning and the high-precision positioning can be maintained, as with one or more embodiments of the first example. 
         [0077]    Furthermore, in one or more embodiments of the second example, the optical system holding portion  140  and the housing  160  are laser welded together as described above. As a result, in addition to the light source holding portion  20  and the optical system holding portion  140 , fixing can also be performed with high-precision positioning on the optical system holding portions  140  and the housing  160 . 
         [0078]    The other effects of one or more embodiments of the second example may be the same as those of the first example. 
       Third Example 
       [0079]    Next, one or more embodiments of the third example will be described with reference to  FIGS. 1 ,  2 , and  11 . In one or more embodiments of this third example, an example will be described where an optical system holding portion and a housing are fixed by a biasing member, different from one or more embodiments of the first and second examples. Configurations that are the same or substantially similar as those in the first and second examples will be shown with the same numerals and descriptions thereof are omitted. 
         [0080]    A head up display device  300  according to one or more embodiments of the second example of the present invention (refer to  FIG. 1 ) comprises a light source unit  201  as illustrated in  FIG. 2 . The light source unit  201  includes three biasing members  290  made up of a plate spring as illustrated in  FIG. 11 . The head up display device  300  is one example of a “projector” of the present invention. 
         [0081]    In one or more embodiments of the third example, the optical system holding portion  40  and the housing  60  are fixed by the biasing member  290  with the light source holding portion  20  and the optical system holding portion  40  laser welded. Specifically, in the light source unit  201 , the optical system holding portion  40  and the housing  60  are fixed by the optical system holding portion  40  being biased toward the inner side of the housing  60  (inner portion side where the three prisms  51   a  to  51   c  are arranged) by the biasing member  290 . The three biasing members  290  are provided in positions corresponding to the three optical system holding portions  40 . 
         [0082]    Two biasing portions  291  are provided on the biasing members  290  for biasing the optical system holding portions  40  toward the inner side of the housing  60 . The two biasing portions  291  are each formed in a position of point symmetry sandwiching the laser diode  10 . 
         [0083]    The other configurations of one or more embodiments of the third example may be the same as those of the first example. 
         [0084]    The following effects can be achieved in one or more embodiments of the third example. 
         [0085]    In one or more embodiments of the third example, the optical system holding portion  40  and the housing  60  are fixed by the biasing member  290  as described above. As a result, the fixing structure of the optical system holding portion  40  and the housing  60  can be a simple fixing structure by the biasing member  290  made up of a plate spring, similar to the fixing structure by the screw member  71  (refer to  FIG. 9 ). 
         [0086]    The other effects of one or more embodiments of the third example may be the same as those of the first example. 
         [0087]    One or more embodiments of the examples disclosed are all examples, and should be considered as non-restrictive. The scope of the present invention is shown in the scope of the claims and not in the description of the embodiments above, and all changes (variations) for the scope and meanings of the claims are included therein. 
         [0088]    For example, in one or more embodiments of the first through third examples described above, an example was shown where one or more embodiments of the present invention was applied to a projector as the head up display (HUD) device  100  ( 200 ,  300 ), but the present invention is not so limited. One or more embodiments of the present invention may be applied to projectors other than projectors as HUD devices. For example, one or more embodiments of the present invention may be applied to a projector that projects a video from an external apparatus such as a PC or television device. 
         [0089]    Furthermore, in one or more embodiments of the first through third examples described above, an example was shown where one or more embodiments of the present invention was applied to the HUD device  100  ( 200 ,  300 ) mounted on a transportation apparatus, but the present invention is not so limited. One or more embodiments of the present invention can also be applied to a HUD device other than a HUD device mounted on a transportation apparatus. 
         [0090]    Moreover, in one or more embodiments of the first through third examples described above, an example was given where the light source holding portion  20  and the optical system holding portion  40  ( 140 ) are laser welded in two positions (positions corresponding to the two welding fixing portions  22 ), but the present invention is not so limited. In one or more embodiments of the present invention, the light source holding portion and the optical system holding portion may be laser welded in one or three or more positions. 
         [0091]    Furthermore, in one or more embodiments of the first example, the light source holding portion  20  is made of light transmitting resin, and the optical system holding portion  40  is made of light absorbing resin, but the present invention is not so limited. In one or more embodiments of the present invention, the light source holding portion may be made of light absorbing resin, and the optical system holding portion may be made of light transmitting resin. Furthermore, in addition, the light source holding portion and the optical system holding portion may both be made of light transmitting resin, and a light absorbing body may be sandwiched between the light source holding portion and the optical system holding portion. 
         [0092]    Furthermore, in one or more embodiments of the first example, the protruding portion  22   a  of the welding fixing portion  22  of the light source holding portion  20  were provided, so that a gap exists around a laser welding region of the light source holding portion  20  and the optical system holding portion  40 ,  140 . The gap may be between 0 and 100 μm long (excluding 0 μm but including 100 μm). However, the present invention is not so limited. In one or more embodiments of the present invention, the protruding portion may not be provided on the welding fixing portion of the light source holding portion. In this case, the light source holding portion and the glass plate may be sufficiently adhered so that a recessed portion is not formed on the position where the laser light of the laser welding will be irradiated. 
         [0093]    Furthermore, the optical system holding portion  40  and the housing  60  are fixed by the screw members  71  in one or more embodiments of the first example described above, the optical system holding portion  140  and the housing  160  are fixed by laser welding in one or more embodiments of the second example described above, and the optical system holding portion  40  and the housing  60  are fixed by a biasing member  290  in one or more embodiments of the third example described above, but the present invention is not so limited. In one or more embodiments of the present invention, the optical system holding portion and the housing may be fixed using methods other such screw member, laser welding, and biasing member. For example, the optical system holding portion and housing may be fixed by an adhesive such as UV cured adhesive. 
         [0094]    Moreover, in one or more embodiments of the first example described above, polyphenylene sulfide (PPS) was used as a light transmitting resin and a light absorbing resin, but the present invention is not so limited. In one or more embodiments of the present invention, a resin material other than PPS may be used as a light transmitting resin and a light absorbing resin. For example. An ABS resin or a PP resin may be used as the light transmitting resin and the light absorbing resin. Furthermore, the light transmitting resin and the light absorbing resin may be configured from different resins. The resin material used for the light transmitting resin and the light absorbing resin may be suitably determined based on the usage conditions (for example, condition of heat resistance) of the projector and head up display device where one or more embodiments of the present invention are applied. 
       REFERENCE NUMERALS 
       [0000]    
       
           1 ,  101 ,  201  Light source unit (or light source portion) 
           2  Optical scanning portion 
           10 ,  10   a ,  10   b ,  10   c  Laser diode (light source) 
           20  Light source holding portion (or first holder) 
           22   a  Protruding portion 
           30  Collimator lens (optical system) (or optical portion) 
           40 ,  140  Optical system holding portion (or second holder) 
           60 ,  160  Housing 
           71  Screw member (fastening member) 
           100 ,  200 ,  300 , Head up display device (projector)