Patent Publication Number: US-2023163256-A1

Title: Light source device and projector

Description:
The present application is based on, and claims priority from JP Application Serial Number 2021-188539, filed Nov. 19, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a light source device and a projector. 
     2. Related Art 
     As a light source device used for a projector, there is proposed a light source device using fluorescence emitted from a phosphor when irradiating the phosphor with excitation light emitted from a light emitting element. 
     In International Patent Publication No. WO 2020/254455, there is disclosed a light source device provided with an excitation light source for emitting excitation light, a phosphor shaped like a rod for converting the excitation light into fluorescence, and a mirror for reflecting the fluorescence generated inside the phosphor. The fluorescence is emitted from one end surface of the phosphor. The mirror is disposed on an end surface at an opposite side to the end surface from which the fluorescence is emitted. 
     However, in the light source device in WO 2020/254455 a part of the fluorescence generated inside the phosphor is not taken out from the end surface, but is confined inside the phosphor in some cases. Therefore, there is a possibility that the fluorescence having desired intensity cannot be obtained. 
     SUMMARY 
     In view of the problems described above, a light source device according to an aspect of the present disclosure includes a light emitting element having a light emitting surface configured to emit first light having a first wavelength band, a wavelength conversion member which includes a phosphor, and which is configured to convert the first light emitted from the light emitting element into second light having a second wavelength band different from the first wavelength band, and a reflecting member having a reflecting surface configured to reflect the second light generated by the wavelength conversion member. The wavelength conversion member has a first face which crosses a longitudinal direction of the wavelength conversion member, and which emits the second light, a second face which crosses the longitudinal direction of the wavelength conversion member, and which is located at an opposite side to the first face, and a third face crossing the first face and the second face. The light emitting surface is disposed so as to be opposed to at least a part of the third face. The reflecting surface is disposed so as to be opposed to the second face. At least one of the second face and the reflecting surface is a rough surface. 
     A projector according to an aspect of the present disclosure includes the light source device according to the aspect of the present disclosure, a light modulation device configured to modulate light including the second light from the light source device in accordance with image information, and a projection optical device configured to project the light modulated by the light modulation device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic configuration diagram of a projector according to a first embodiment. 
         FIG.  2    is a schematic configuration diagram of a first illumination device according to the first embodiment. 
         FIG.  3    is a schematic configuration diagram of a first illumination device according to a comparative example. 
         FIG.  4    is a schematic configuration diagram of a first illumination device according to a second embodiment. 
         FIG.  5    is a schematic configuration diagram of a first illumination device according to a third embodiment. 
         FIG.  6    is a schematic configuration diagram of a first illumination device according to a fourth embodiment. 
         FIG.  7    is a schematic configuration diagram of a first illumination device according to a fifth embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     First Embodiment 
     A first embodiment of the present disclosure will hereinafter be described using  FIG.  1    through  FIG.  3   . 
     A projector according to the present embodiment is an example of a projector using liquid crystal panels as light modulation devices. 
     In the drawings described below, constituents are shown with respective dimensional scale ratios different from each other in some cases in order to make the constituents eye-friendly. 
       FIG.  1    is a diagram showing a schematic configuration of the projector  1  according to the present embodiment. 
     As shown in  FIG.  1   , the projector  1  according to the present embodiment is a projection-type image display device for displaying a color image on a screen (a projection target surface) SCR. The projector  1  is provided with three light modulation devices corresponding to respective colored light, namely red light LR, green light LG, and blue light LB. 
     The projector  1  is provided with a first illumination device  20 , a second illumination device  21 , a color separation optical system  3 , a light modulation device  4 R, a light modulation device  4 G, a light modulation device  4 B, a light combining element  5 , and a projection optical device  6 . 
     The first illumination device  20  emits fluorescence Y having a yellow color toward the color separation optical system  3 . The second illumination device  21  emits the blue light LB toward the light modulation device  4 B. The detailed configurations of the first illumination device  20  and the second illumination device  21  will be described later. 
     Hereinafter, in the drawings, the explanation will be presented using an XYZ coordinate system as needed. A Z axis is an axis extending along a vertical direction of the projector  1 . An X axis is an axis parallel to an optical axis AX 1  of the first illumination device  20  and an optical axis AX 2  of the second illumination device  21 . A Y axis is an axis perpendicular to the X axis and the Z axis. The optical axis AX 1  of the first illumination device  20  is a central axis of the fluorescence Y emitted from the first illumination device  20 . The optical axis AX 2  of the second illumination device  21  is a central axis of the blue light LB emitted from the second illumination device  21 . 
     The color separation optical system  3  separates the fluorescence Y having the yellow color emitted from the first illumination device  20  into the red light LR and the green light LG. The color separation optical system  3  is provided with a dichroic mirror  7 , a first reflecting mirror  8   a , and a second reflecting mirror  8   b.    
     The dichroic mirror  7  separates the fluorescence Y into the red light LR and the green light LG. The dichroic mirror  7  transmits the red light LR, and at the same time, reflects the green light LG. The second reflecting mirror  8   b  is disposed in a light path of the green light LG. The second reflecting mirror  8   b  reflects the green light LG, which has been reflected by the dichroic mirror  7 , toward the light modulation device  4 G. The first reflecting mirror  8   a  is disposed in a light path of the red light LR. The first reflecting mirror  8   a  reflects the red light LR, which has been transmitted through the dichroic mirror  7 , toward the light modulation device  4 R. 
     Meanwhile, the blue light LB emitted from the second illumination device  21  is reflected by a reflecting mirror  9  toward the light modulation device  4 B. 
     A configuration of the second illumination device  21  will hereinafter be described. 
     The second illumination device  21  is provided with a light source  81 , a condenser lens  82 , a diffuser plate  86 , a rod lens  84 , and a relay lens  85 . The light source  81  is formed of at least one semiconductor laser. The light source  81  emits the blue light LB consisting of a laser beam. It should be noted that the light source  81  is not limited to the semiconductor laser, but can also be formed of an LED for emitting blue light. 
     The condenser lens  82  is formed of a convex lens. The condenser lens  82  makes the blue light LB emitted from the light source  81  enter the diffuser plate  86  in a state in which the blue light LB emitted from the light source  81  is substantially converged. The diffuser plate  86  diffuses the blue light LB emitted from the condenser lens  82  at a predetermined diffusion angle to generate a substantially homogenous light distribution substantially the same as that of the fluorescence Y emitted from the first illumination device  20 . As the diffuser plate  86 , there is used, for example, obscured glass made of optical glass. 
     The blue light LB diffused by the diffuser plate  86  enters the rod lens  84 . The rod lens  84  has a prismatic shape extending along a direction of the optical axis AX 2  of the second illumination device  21 . The rod lens  84  has an end plane of incidence of light  84   a  disposed at one end, and a light exit end surface  84   b  disposed at the other end. The diffuser plate  86  is fixed to the end plane of incidence of light  84   a  of the rod lens  84  via an optical adhesive (not shown). It is desirable to make the refractive index of the diffuser plate  86  and the refractive index of the rod lens  84  coincide with each other as precise as possible. 
     The blue light LB is emitted from the light exit end surface  84   b  in the state in which homogeneity of an illuminance distribution is enhanced by propagating through the rod lens  84  while being totally reflected. The blue light LB emitted from the rod lens  84  enters the relay lens  85 . The relay lens  85  makes the blue light LB enhanced in homogeneity of the illuminance distribution by the rod lens  84  enter the reflecting mirror  9 . 
     The shape of the light exit end surface  84   b  of the rod lens  84  is a rectangular shape substantially similar to a shape of an image formation area of the light modulation device  4 B. Thus, the blue light LB emitted from the rod lens  84  efficiently enters the image formation area of the light modulation device  4 B. 
     The light modulation device  4 R modulates the red light LR in accordance with image information to form image light corresponding to the red light LR. The light modulation device  4 G modulates the green light LG in accordance with the image information to form image light corresponding to the green light LG. The light modulation device  4 B modulates the blue light LB in accordance with the image information to form image light corresponding to the blue light LB. 
     As each of the light modulation devices  4 R,  4 G, and  4 B, there is used, for example, a transmissive liquid crystal panel. Further, on the incident side and the exit side of each of the liquid crystal panels, there are respectively disposed polarization plates (not shown). The polarization plate transmits linearly-polarized light of a specific direction. 
     At the incident side of the light modulation device  4 R, there is disposed a field lens  10 R. At the incident side of the light modulation device  4 G, there is disposed a field lens  10 G. At the incident side of the light modulation device  4 B, there is disposed a field lens  10 B. The field lens  10 R collimates a principal ray of the red light LR entering the light modulation device  4 R. The field lens  10 G collimates a principal ray of the green light LG entering the light modulation device  4 G. The field lens  10 B collimates a principal ray of the blue light LB entering the light modulation device  4 B. 
     The light combining element  5  combines the image light corresponding respectively to the red light LR, the green light LG, and the blue light LB with each other in response to incidence of the image light respectively emitted from the light modulation device  4 R, the light modulation device  4 G, and the light modulation device  4 B, and then emits the image light thus combined toward the projection optical device  6 . As the light combining element  5 , there is used, for example, a cross dichroic prism. 
     The projection optical device  6  is constituted by a plurality of projection lenses. The projection optical device  6  projects the image light having been combined by the light combining element  5  toward the screen SCR in an enlarged manner. Thus, an image is displayed on the screen SCR. 
     A configuration of the first illumination device  20  will hereinafter be described. 
       FIG.  2    is a schematic configuration diagram of the first illumination device  20 . 
     As shown in  FIG.  2   , the first illumination device  20  is provided with a light source device  100 , an integrator optical system  70 , a polarization conversion element  102 , and a superimposing optical system  103 . 
     The light source device  100  is provided with a wavelength conversion member  50 , light sources  51 , a reflecting member  53 , an angle conversion member  52 , and a bonding member  59 . The light sources  51  are each provided with a substrate  55  and light emitting elements  56 . 
     The wavelength conversion member  50  has a quadrangular prismatic shape extending in the X-axis direction, and has six faces. A side extending in the X-axis direction of the wavelength conversion member  50  is longer than a side extending in the Y-axis direction and a side extending in the Z-axis direction. Therefore, the X-axis direction corresponds to a longitudinal direction of the wavelength conversion member  50 . The length of the side extending in the Y-axis direction and the length of the side extending in the Z-axis direction are equal to each other. In other words, a cross-sectional shape of the wavelength conversion member  50  cut by a plane perpendicular to the X-axis direction is a square. It should be noted that the cross-sectional shape of the wavelength conversion member  50  cut by the plane perpendicular to the X-axis direction can be a rectangle. 
     The wavelength conversion member  50  has a first face  50   a  which crosses the longitudinal direction (the X-axis direction) of the wavelength conversion member  50 , and emits fluorescence Y described later, a second face  50   b  which crosses the longitudinal direction (the X-axis direction) of the wavelength conversion member  50 , and is located at an opposite side to the first face  50   a , a first side surface  50   c  and a second side surface  50   d  which cross the first face  50   a  and the second face  50   b , and are located at respective sides opposite to each other, and a third side surface and a fourth side surface (not shown) which cross the first side surface  50   c  and the second side surface  50   d , and are located at respective sides opposite to each other. In the following description, four faces, namely the first side surface  50   c , the second side surface  50   d , the third side surface, and the fourth side surface, are collectively referred to as side surfaces  50   g . The side surfaces  50   g  in the present embodiment correspond to a third surface in the appended claims. 
     It should be noted that the wavelength conversion member  50  is not necessarily required to have the quadrangular prismatic shape, but can also have other shapes such as a triangular prismatic shape or a cylindrical shape. When the shape of the wavelength conversion member  50  is a triangular prismatic shape, three faces crossing the first face and the second face are collectively referred to as the side surfaces  50   g . When the shape of the wavelength conversion member  50  is a cylindrical shape, a single continuous curved surface crossing the first face and the second face is referred to as the side surface  50   g.    
     The wavelength conversion member  50  includes at least a phosphor, and converts excitation light E having a first wavelength band into the fluorescence Y having a second wavelength band different from the first wavelength band. In the present embodiment, the excitation light E enters the wavelength conversion member  50  from each of the first side surface  50   c  and the second side surface  50   d . The fluorescence Y is guided inside the wavelength conversion member  50 , and is then emitted from the first face  50   a . The excitation light E in the present embodiment corresponds to first light in the appended claims. The fluorescence Y in the present embodiment corresponds to second light in the appended claims. 
     The wavelength conversion member  50  includes a ceramic phosphor made of a polycrystalline phosphor for performing the wavelength conversion on the excitation light E into the fluorescence Y. The second wavelength band which the fluorescence Y has is a yellow wavelength band of, for example, 490 through 750 nm. Therefore, the fluorescence Y is yellow fluorescence including a red light component and a green light component. 
     It is also possible for the wavelength conversion member  50  to include a single-crystal phosphor instead of the polycrystalline phosphor. Alternatively, the wavelength conversion member  50  can also be formed of fluorescent glass. Alternatively, the wavelength conversion member  50  can also be formed of a material obtained by dispersing a number of phosphor particles in a binder made of glass or resin. The wavelength conversion member  50  made of such a material converts the excitation light E into the fluorescence Y having the second wavelength band. 
     Specifically, the material of the wavelength conversion member  50  includes, for example, an yttrium aluminum garnet (YAG) phosphor. Citing YAG:Ce including cerium (Ce) as an activator agent as an example, as the material of the wavelength conversion member  50 , there is used a material obtained by mixing raw powder including constituent elements such as Y 2 O 3 , Al 0  and CeO 3  to cause the solid-phase reaction, Y—Al—O amorphous particles obtained by a wet process such as a coprecipitation process or a sol-gel process, and YAG particles obtained by a gas-phase process such as a spray drying process, a flame heat decomposition process or a thermal plasma process. 
     The light sources  51  are each provided with the light emitting elements  56  each having a light emitting surface  56   a  for emitting the excitation light E in the first wavelength band. The light sources  51  are disposed so as to be respectively opposed to the first side surface  50   c  and the second side surface  50   d  of the wavelength conversion member  50 . The light emitting elements  56  are each formed of, for example, a light emitting diode (LED). As described above, the light sources  51  are each disposed so as to be opposed to a part of the side surfaces  50   g  along the longitudinal direction of the wavelength conversion member  50 . It should be noted that the number and the arrangement of the light sources  51  are not particularly limited. 
     The light emitting surfaces  56   a  of the light emitting elements  56  are arranged so as to respectively be opposed to the first side surface  50   c  and the second side surface  50   d  of the wavelength conversion member  50 , and emit the excitation light E toward the first side surface  50   c  and the second side surface  50   d , respectively. The first wavelength band is, for example, a wavelength band from a blue color to a violet color of 400 nm through 480 nm, and has a peak wavelength of, for example, 445 nm. 
     The substrate  55  supports the light emitting elements  56 . The plurality of light emitting elements  56  is disposed on one surface  55   a  of the substrate  55 . The light sources  51  are each constituted by the light emitting elements  56  and the substrate  55  in the case of the present embodiment, but can also be provided with other optical members such as a light guide plate, a diffuser plate, or a lens. Further, the number of the light emitting elements  56  provided to the substrate  55  is not particularly limited. 
     The reflecting member  53  is disposed so as to be opposed to the second face  50   b  of the wavelength conversion member  50 . The reflecting member  53  reflects the fluorescence Y which has been guided inside the wavelength conversion member  50 , and has reached the second face  50   b . The reflecting member  53  is a member separated from the wavelength conversion member  50 , and is formed of a plate-like member made of a metal material such as aluminum. The reflecting member  53  has a reflecting surface  53   r  which is opposed to the second face  50   b  of the wavelength conversion member  50 , and which reflects the fluorescence Y. The reflecting surface  53   r  can be a surface of the metal material itself, or can be formed of a metal film or a dielectric multilayer film formed on the surface of the metal material. 
     In the light source device  100 , when the excitation light E emitted from the light emitting element  56  enters the wavelength conversion member  50 , the phosphor included in the wavelength conversion member  50  is excited, and the fluorescence Y is emitted from an arbitrary light emitting point. The fluorescence Y proceeds from the arbitrary light emitting point toward all directions, but the fluorescence Y proceeding toward the side surfaces  50   g  proceeds toward the first face  50   a  or the second face  50   b  while repeating the total reflection at a plurality of places in the side surfaces  50   g . The fluorescence Y proceeding toward the first face  50   a  enters the angle conversion member  52 . Meanwhile, the fluorescence Y proceeding toward the second face  50   b  is reflected by the reflecting member  53 , and then proceeds toward the first face  50   a.    
     A part of the excitation light E which has not been used for the excitation of the phosphor out of the excitation light E having entered the wavelength conversion member  50  is reflected by a member on the periphery of the wavelength conversion member  50  including the light emitting element  56  of the light source  51 , or the reflecting member  53  disposed on the second face  50   b . Therefore, the part of the excitation light E is confined inside the wavelength conversion member  50  to be reused. 
     The angle conversion member  52  is disposed on the light exit side of the first face  50   a  of the wavelength conversion member  50 . The angle conversion member  52  is formed of, for example, a taper rod. The angle conversion member  52  has a plane of incidence of light  52   a  which the fluorescence Y emitted from the wavelength conversion member  50  enters, a light exit surface  52   b  for emitting the fluorescence Y, and a side surface  52   c  for reflecting the fluorescence Y toward the light exit surface  52   b.    
     The angle conversion member  52  has a truncated quadrangular pyramid-like shape, and the area of a cross-section perpendicular to an optical axis J increases along the proceeding direction of the light. Therefore, the area of the light exit surface  52   b  is larger than the area of the plane of incidence of light  52   a . An axis which passes through the center of the light exit surface  52   b  and the center of the plane of incidence of light  52   a , and is parallel to the X axis is defined as the optical axis J of the angle conversion member  52 . It should be noted that the optical axis J of the angle conversion member  52  coincides with the optical axis AX 1  of the first illumination device  20 . 
     The fluorescence Y having entered the angle conversion member  52  changes the direction so as to approximate to a direction parallel to the optical axis J every time the fluorescence Y is totally reflected by the side surface  52   c  while proceeding inside the angle conversion member  52 . In such a manner, the angle conversion member  52  converts an exit angle distribution of the fluorescence Y emitted from the first face  50   a  of the wavelength conversion member  50 . Specifically, the angle conversion member  52  makes a maximum exit angle of the fluorescence Y in the light exit surface  52   b  smaller than a maximum incident angle of the fluorescence Y in the plane of incidence of light  52   a.    
     In general, since an etendue of light defined by a product of the area of the light exit region and a solid angle (the maximum exit angle) of the light is conserved, the etendue of the fluorescence Y is also conserved before and after the transmission through the angle conversion member  52 . As described above, the angle conversion member  52  in the present embodiment has the configuration in which the area of the light exit surface  52   b  is made larger than the area of the plane of incidence of light  52   a . Therefore, from a viewpoint of the conservation of the etendue, it is possible for the angle conversion member  52  in the present embodiment to make the maximum exit angle of the fluorescence Y in the light exit surface  52   b  smaller than the maximum incident angle of the fluorescence Y entering the plane of incidence of light  52   a.    
     The angle conversion member  52  is fixed to the wavelength conversion member  50  via the bonding member  59  so that the plane of incidence of light  52   a  is opposed to the first face  50   a  of the wavelength conversion member  50 . In other words, the bonding member  59  is disposed between the angle conversion member  52  and the first face  50   a  of the wavelength conversion member  50 . 
     It is also possible to use a compound parabolic concentrator (CPC) instead of the taper rod as the angle conversion member  52 . Even when using the CPC as the angle conversion member  52 , it is also possible to obtain substantially the same advantages as those when using the taper rod. It should be noted that the light source device  100  is not necessarily required to be provided with the angle conversion member  52 . 
     The integrator optical system  70  has a first lens array  61  and a second lens array  101 . The integrator optical system  70  constitutes a homogenous illumination optical system for homogenizing an intensity distribution of the fluorescence Y emitted from the light source device  100  in each of the light modulation devices  4 R,  4 G as the illumination target area in cooperation with the superimposing optical system  103 . The fluorescence Y emitted from the light exit surface  52   b  of the angle conversion member  52  enters the first lens array  61 . The first lens array  61  constitutes the integrator optical system  70  together with the second lens array  101  disposed in a posterior stage of the light source device  100 . 
     The first lens array  61  has a plurality of first small lenses  61   a . The plurality of first small lenses  61   a  is arranged in a matrix in a plane parallel to a Y-Z plane perpendicular to the optical axis AX 1  of the first illumination device  20 . The plurality of first small lenses  61   a  divides the fluorescence Y emitted from the angle conversion member  52  into a plurality of partial light beams. A shape of each of the first small lenses  61   a  is a rectangular shape substantially similar to a shape of each of the image formation areas of the light modulation devices  4 R,  4 G. Thus, each of partial light beams emitted from the first lens array  61  efficiently enters each of the image formation areas of the light modulation devices  4 R,  4 G. 
     The fluorescence Y emitted from the first lens array  61  proceeds toward the second lens array  101 . The second lens array  101  is arranged so as to be opposed to the first lens array  61 . The second lens array  101  has a plurality of second small lenses  101   a  corresponding to the plurality of first small lenses  61   a  of the first lens array  61 . The second lens array  101  focuses an image of each of the first small lenses  61   a  of the first lens array  61  in the vicinity of each of the image formation areas of the light modulation devices  4 R,  4 G in cooperation with the superimposing optical system  103 . The plurality of second small lenses  101   a  is arranged in a matrix in a plane parallel to the Y-Z plane perpendicular to the optical axis AX 1  of the first illumination device  20 . 
     Each of the first small lenses  61   a  of the first lens array  61  and each of the second small lenses  101   a  of the second lens array  101  have respective sizes the same as each other in the present embodiment, but can have respective sizes different from each other. Further, the first small lenses  61   a  of the first lens array  61  and the second small lenses  101   a  of the second lens array  101  are arranged at positions where respective optical axes coincide with each other in the present embodiment, but can be arranged in a state in which the axes are shifted from each other. 
     The polarization conversion element  102  converts the polarization direction of the fluorescence Y emitted from the second lens array  101 . Specifically, the polarization conversion element  102  converts each of the partial light beams of the fluorescence Y which is divided by the first lens array  61 , and is emitted from the second lens array  101  into linearly polarized light. 
     The polarization conversion element  102  has a polarization splitting layer (not shown) for transmitting one of the linearly polarized components included in the fluorescence Y emitted from the light source device  100  without modification while reflecting the other of the linearly polarized components toward a direction perpendicular to the optical axis AX 1 , a reflecting layer (not shown) for reflecting the other of the linearly polarized components reflected by the polarization splitting layer, toward a direction parallel to the optical axis AX 1 , and a wave plate (not shown) for converting the other of the linearly polarized components reflected by the reflecting layer into the one of the linearly polarized components. 
     In the case of the present embodiment, the second face  50   b  of the wavelength conversion member  50  is a rough surface. In contrast, the reflecting surface  53   r  of the reflecting member  53  is a smooth surface. It is desirable for the surface roughness of the second face  50   b  to be no smaller than 2 μm in arithmetic mean roughness. Further, it is more desirable for the surface roughness of the second face  50   b  to be no smaller than 10 μm in arithmetic mean roughness. Further, a pitch between a ridge and a bottom adjacent to each other of the rough surface is desirably no smaller than the wavelength band of the fluorescence Y, and is desirably no smaller than, for example, 0.7 μm. A part of the second face  50   b  of the wavelength conversion member  50  has contact with the reflecting surface  53   r  of the reflecting member  53 . It is desirable for the surface roughness of the reflecting surface  53   r  to be smaller than 2 μm in arithmetic mean roughness. As a method of making the second face  50   b  of the wavelength conversion member  50  as the rough surface, there are cited a method of cutting the second face  50   b  of the wavelength conversion member  50  with a wire saw, a method of sandblasting the second face  50   b , a method of performing abrasive processing on the second face  50   b  with an abrasive compound such as alumina, and so on. 
     Comparative Example 
     Then, a light source device according to a comparative example will be described. 
       FIG.  3    is a schematic configuration diagram of a first illumination device  220  according to the comparative example. 
     As shown in  FIG.  3   , the first illumination device  220  according to the comparative example is provided with a light source device  200 . The light source device  200  is provided with the light emitting elements  56 , a wavelength conversion member  250 , the reflecting member  53 , and the angle conversion member  52 . The light source device  200  according to the comparative example is different from the light source device  100  according to the present embodiment only in a configuration of the wavelength conversion member  250 . Therefore, in  FIG.  3   , members other than the wavelength conversion member  250  are denoted by the reference symbols common to  FIG.  2   , and the description thereof will be omitted. 
     As shown in  FIG.  3   , in the light source device  200  according to the comparative example, a second face  250   b  of the wavelength conversion member  250  is not such a rough surface as in the present embodiment, but is a smooth surface. Further, the reflecting surface  53   r  of the reflecting member  53  is a smooth surface. The second face  250   b  and the reflecting surface  53   r  have contact with each other. 
     In the light source device of this kind, in general, the angle conversion member is formed of a transparent material such as glass, the bonding member is formed of an optical adhesive, and the wavelength conversion member includes a phosphor material. In this case, a refractive index of the angle conversion member and a refractive index of the bonding member substantially coincide with each other, and the refractive index of the angle conversion member and a refractive index of the wavelength conversion member are different from each other. In general, the optical adhesive is lower in refractive index than the wavelength conversion member. 
     Therefore, as shown in  FIG.  3   , the fluorescence Y which enters a first face  250   a  of the wavelength conversion member  250  at an incident angle equal to or larger than the critical angle out of the fluorescence having reached the first face  250   a  is totally reflected by an interface between the first face  250   a  of the wavelength conversion member  250  and the bonding member  59 , proceeds toward the second face  250   b , and then enters the second face  250   b . In the case of the light source device  200  according to the comparative example, since both of the second face  250   b  of the wavelength conversion member  250  and the reflecting surface  53   r  of the reflecting member  53  are the smooth surfaces, fluorescence Y 1  having entered the second face is totally reflected without changing the angle, and then proceeds toward the first face  250   a  once again. 
     As a result, the fluorescence Y 1  repeatedly propagates inside the wavelength conversion member  250  in the state in which the angle is conserved, and is therefore confined inside the wavelength conversion member  250 . In the light source device  200  according to the comparative example, since the fluorescence Y 1  of this kind exists, an extraction efficiency of the whole of the fluorescence decreases, and there is a possibility that it is unachievable to obtain the fluorescence having the desired intensity. 
     Advantages of First Embodiment 
     The light source device  100  according to the present embodiment is provided with the light emitting element  56  having the light emitting surface  56   a  for emitting the excitation light E having the first wavelength band, the wavelength conversion member  50  which includes the phosphor to convert the excitation light E emitted from the light emitting element  56  into the fluorescence Y having the second wavelength band different from the first wavelength band, and the reflecting member  53  having the reflecting surface  53   r  for reflecting the fluorescence Y generated in the wavelength conversion member  50 . The wavelength conversion member  50  has the first face  50   a  which crosses the longitudinal direction of the wavelength conversion member  50 , and which emits the fluorescence Y, the second face  50   b  which crosses the longitudinal direction of the wavelength conversion member  50 , and which is located at the opposite side to the first face  50   a , and the side surfaces  50   g  crossing the first face  50   a  and the second face  50   b . The light emitting surface  56   a  is disposed so as to be opposed to at least a part of the side surfaces  50   g . The reflecting surface  53   r  is disposed so as to be opposed to the second face  50   b . The second face  50   b  is a rough surface, and the reflecting surface  53   r  is a smooth surface. 
     According to the light source device  100  related to the present embodiment, as shown in  FIG.  2   , the fluorescence Y 1  which is totally reflected by the first face  50   a  of the wavelength conversion member  50 , and then enters the second face  50   b  is reflected in a scattered manner by the second face  50   b  formed of the rough surface, and therefore, there is generated fluorescence Y 2  having the angle variously changed. 
     Thus, at least a part of the fluorescence Y 2  reflected in a scattered manner by the second face  50   b  enters the first face  50   a  of the wavelength conversion member  50  at the incident angle smaller than the critical angle, and is therefore transmitted through the first face  50   a  and taken out to the outside of the light source device  100  without being totally reflected by the first face  50   a.    
     As described hereinabove, according to the light source device  100  related to the present embodiment, it is possible to provide the light source device which is high in extraction efficiency of the fluorescence Y compared to the light source device  200  according to the comparative example, and is easy to obtain the fluorescence Y having the desired intensity. 
     The light source device  100  according to the present embodiment is further provided with the angle conversion member  52  which is disposed so as to be opposed to the first face  50   a , and converts the angle distribution of the fluorescence Y emitted from the first face  50   a , and the bonding member  59  disposed between the angle conversion member  52  and the first face  50   a.    
     According to this configuration, even in a configuration in which the refractive index of the angle conversion member  52  and the refractive index of the wavelength conversion member  50  are different from each other, and it is easy for the fluorescence Y to totally be reflected by the first face  50   a  of the wavelength conversion member  50 , by the fluorescence Y 1  being reflected in a scattered manner by the second face  50   b , it becomes easy for the fluorescence Y 1  to be taken out to the outside of the light source device  100 . Further, by the fluorescence Y emitted from the first face  50   a  of the wavelength conversion member  50  being transmitted through the angle conversion member  52 , the angle distribution of the fluorescence Y is narrowed. Thus, it is possible to increase the light use efficiency in the optical system in the posterior stage of the light source device  100 . 
     The projector  1  according to the present embodiment is equipped with the light source device  100  according to the present embodiment, and is therefore excellent in light use efficiency. 
     Second Embodiment 
     Then, a second embodiment of the present disclosure will be described using  FIG.  4   . 
     A basic configuration of a projector and a light source device according to the second embodiment is substantially the same as that in the first embodiment, and therefore, the description of the basic configuration of the projector and the light source device will be omitted. 
       FIG.  4    is a schematic configuration diagram of a first illumination device  320  according to the second embodiment. 
     In  FIG.  4   , the constituents common to the drawing used in the first embodiment are denoted by the same reference symbols, and the description thereof will be omitted. 
     As shown in  FIG.  4   , the first illumination device  320  according to the present embodiment is provided with a light source device  120 . The light source device  120  is provided with the light emitting elements  56 , the wavelength conversion member  50 , a reflecting member  63 , the angle conversion member  52 , and the bonding member  59 . 
     In the light source device  120  according to the present embodiment, the reflecting member  63  has a base  630  and a wall  631 . The base  630  is disposed so as to be opposed to the second face  50   b , and has a reflecting surface  63   r  opposed to the second face  50   b . The wall  631  continues from the base  630 , and is disposed so as to be opposed to a part of the side surfaces  50   g  at a side near to the second face  50   b . In other words, in contrast to the reflecting member  53  in the first embodiment which is opposed only to the second face  50   b , the reflecting member  63  in the present embodiment is also opposed to a part of the side surfaces  50   g  in addition to the second face  50   b . The base  630  and the wall  631  are formed of an integrated single member in the case of the present embodiment, but can also be formed of separated members. The rest of the configuration of the light source device  120  is substantially the same as in the first embodiment. 
     Advantages of Second Embodiment 
     Also in the present embodiment, it is possible to obtain substantially the same advantages as in the first embodiment such as an advantage that it is possible to realize the light source device  120  which is high in extraction efficiency of the fluorescence Y, and is easy to obtain the fluorescence Y having the desired intensity. 
     Further, in the light source device  120  according to the present embodiment, the reflecting member  63  has the base  630  disposed so as to be opposed to the second face  50   b , and the wall  631  which continues from the base  630 , and is disposed so as to opposed to a part of the side surfaces  50   g.    
     In the case of the first embodiment, there is a possibility that the fluorescence Y which enters a corner between the second face  50   b  of the wavelength conversion member  50  and the side surface  50   g  is leaked outside. In contrast, according to the configuration of the present embodiment, since the corner  50 R between the second face  50   b  of the wavelength conversion member  50  and the side surface  50   g  is covered with the reflecting member  63 , the fluorescence Y which enters the corner  50 R between the second face  50   b  of the wavelength conversion member  50  and the side surface  50   g  can be reflected to thereby be returned to the wavelength conversion member  50 , and thus, it is possible to reduce a loss of the fluorescence Y. 
     Third Embodiment 
     Then, a third embodiment of the present disclosure will be described using  FIG.  5   . 
     A basic configuration of a projector and a light source device according to the third embodiment is substantially the same as that in the first embodiment, and therefore, the description of the basic configuration of the projector and the light source device will be omitted. 
       FIG.  5    is a schematic configuration diagram of a first illumination device  330  according to the third embodiment. 
     In  FIG.  5   , the constituents common to the drawings used in the previous embodiments are denoted by the same reference symbols, and the description thereof will be omitted. 
     As shown in  FIG.  5   , the first illumination device  330  according to the present embodiment is provided with a light source device  130 . The light source device  130  is provided with the light emitting elements  56 , a wavelength conversion member  60 , a reflecting member  73 , the angle conversion member  52 , and the bonding member  59 . The wavelength conversion member  60  has a first face  60   a , a second face  60   b , and a side surface  60   g  including a third face  60   c  and a fourth face  60   d . The reflecting member  73  has a reflecting surface  73   r  opposed to the second face  60   b.    
     In the case of the present embodiment, the second face  60   b  of the wavelength conversion member  60  is a smooth surface. In contrast, the reflecting surface  73   r  of the reflecting member  73  is a rough surface. Specifically, the reflecting surface  73   r  of the reflecting member  73  has a concavo-convex structure. A shape of a protrusion constituting the concavo-convex structure can be, for example, a semispherical shape, a pyramidal shape, or a columnar shape, or can also be an amorphous shape. The height of the protrusion is desirably, for example, about 1 μm through 0.2 mm. A distance between the protrusion and the recess adjacent to each other is desirably, for example, about 1 μm through 0.2 mm. The protrusions and the recesses can be arranged at regular intervals, or are not required to be arranged periodically. Further, it is desirable for the surface roughness of the second face  60   b  of the wavelength conversion member  60  to be smaller than 2 μm in arithmetic mean roughness. The rest of the configuration of the light source device  130  is substantially the same as in the first embodiment. As a method of making the reflecting member  73  as the rough surface, there are cited a method of sandblasting the reflecting surface  73   r , and a method of performing abrasive processing on the reflecting surface  73   r  with an abrasive compound such as alumina. Further, as a method of forming the concavo-convex structure on the reflecting surface  73   r  of the reflecting member  73 , there are cited a method of providing a mask to the reflecting member  73  made of metal such as alumina and then performing wet etching, and a method of etching a base member of the reflecting member  73  to form a concavo-convex pattern, and then forming a reflecting surface on the concavo-convex pattern by evaporation of a metal film or evaporation of a dielectric multilayer film. 
     Advantages of Third Embodiment 
     In the case of the present embodiment, a part of the fluorescence Y 1  which has entered the second face  60   b  at an angle smaller than the critical angle is transmitted through the second face  60   b , and then enters the reflecting surface  73   r  of the reflecting member  73 . Since the reflecting surface  73   r  formed of the rough surface reflects and scatters the fluorescence Y 1  which has been transmitted through the second face  60   b , there is generated the fluorescence Y 2  having the angle variously changed. 
     Thus, at least a part of the fluorescence Y 2  reflected in a scattered manner by the reflecting surface  73   r  enters the first face  60   a  of the wavelength conversion member  60  at the incident angle smaller than the critical angle, and is therefore transmitted through the first face  60   a  and taken out to the outside of the light source device  130  without being totally reflected by the first face  60   a.    
     Therefore, also in the present embodiment, it is possible to obtain substantially the same advantages as in the first embodiment such as an advantage that it is possible to realize the light source device  130  which is high in extraction efficiency of the fluorescence Y, and is easy to obtain the fluorescence Y having the desired intensity. 
     Further, in the present embodiment, since the reflecting surface  73   r  of the reflecting member  73  has the concavo-convex structure, and the second face  60   b  of the wavelength conversion member  60  is the smooth surface, when the processing of the end surface of the wavelength conversion member  60  is difficult, it is possible to easily manufacture the light source device  130 . 
     Fourth Embodiment 
     Then, a fourth embodiment of the present disclosure will be described using  FIG.  6   . 
     A basic configuration of a projector and a light source device according to the fourth embodiment is substantially the same as that in the first embodiment, and therefore, the description of the basic configuration of the projector and the light source device will be omitted. 
       FIG.  6    is a schematic configuration diagram of a first illumination device  340  according to the fourth embodiment. 
     In  FIG.  6   , the constituents common to the drawings used in the previous embodiments are denoted by the same reference symbols, and the description thereof will be omitted. 
     As shown in  FIG.  6   , the first illumination device  340  according to the present embodiment is provided with a light source device  140 . The light source device  140  is provided with the light emitting elements  56 , the wavelength conversion member  60 , a reflecting member  83 , the angle conversion member  52 , and the bonding member  59 . The reflecting member  83  has a reflecting surface  83   r  opposed to the second face  60   b.    
     In the case of the present embodiment, the second face  60   b  of the wavelength conversion member  60  is a smooth surface. The reflecting surface  83   r  of the reflecting member  83  is a rough surface. Specifically, the reflecting surface  83   r  of the reflecting member  83  has a structure in which a plurality of fine protrusions each shaped like a curved surface is arranged periodically. The diameter of the protrusion shaped like a curved surface is desirably, for example, about 1 μm through 0.2 mm. The plurality of protrusions each shaped like a curved surface can be arranged at regular intervals, or is not required to be arranged periodically. The rest of the configuration of the light source device  140  is substantially the same as in the first embodiment. The reflecting surface  83   r  can be realized by forming the reflecting member  83  from a metal material such as alumina, or it is possible to form a metal film or a dielectric multilayer film on the reflecting surface  83   r  using evaporation or the like. 
     Advantages of Fourth Embodiment 
     Also in the present embodiment, since the reflecting surface  83   r  formed of the rough surface reflects and scatters the fluorescence Y 1  which has been transmitted through the second face  60   b , there is generated the fluorescence Y 2  having the angle variously changed. Therefore, it is possible to obtain substantially the same advantages as in the first embodiment such as an advantage that it is possible to realize the light source device  140  which is high in extraction efficiency of the fluorescence Y, and is easy to obtain the fluorescence Y having the desired intensity. 
     In the present embodiment, since the reflecting surface  83   r  of the reflecting member  83  has the structure in which the protrusions each shaped like a curved surface are arranged periodically, when the processing of the end surface of the wavelength conversion member  60  is difficult, it is possible to easily manufacture the light source device  140  similarly to the third embodiment. Further, by appropriately designing the shape and the dimension of the protrusion shaped like a curved surface, it is possible to adjust the reflection angle of the fluorescence Y 1  by the reflecting surface  83   r  to control the angle distribution of the fluorescence Y 2  thus reflected. 
     Fifth Embodiment 
     Then, a fifth embodiment of the present disclosure will be described using  FIG.  7   . 
     A basic configuration of a projector and a light source device according to the fifth embodiment is substantially the same as that in the first embodiment, and therefore, the description of the basic configuration of the projector and the light source device will be omitted. 
       FIG.  7    is a schematic configuration diagram of a first illumination device  350  according to the fifth embodiment. 
     In  FIG.  7   , the constituents common to the drawings used in the previous embodiments are denoted by the same reference symbols, and the description thereof will be omitted. 
     As shown in  FIG.  7   , the first illumination device  350  according to the present embodiment is provided with a light source device  150 . The light source device  150  is provided with the light emitting elements  56 , the wavelength conversion member  50 , the reflecting member  73 , the angle conversion member  52 , and the bonding member  59 . 
     In the case of the present embodiment, the second face  50   b  of the wavelength conversion member  50  is a rough surface. The reflecting surface  73   r  of the reflecting member  73  is a rough surface. In the present embodiment, both of the second face  50   b  and the reflecting surface  73   r  are rough surfaces. It is desirable for the surface roughness of both of the second face  50   b  and the reflecting surface  73   r  to be no smaller than 2 μm in arithmetic mean roughness. Further, it is more desirable for the surface roughness of both of the second face  50   b  and the reflecting surface  73   r  to be no smaller than 10 μm in arithmetic mean roughness. Further, a pitch between a ridge and a bottom adjacent to each other of the rough surface of the second face  50   b  and the reflecting surface  73   r  is desirably no smaller than the wavelength band of the fluorescence Y, and is desirably no smaller than, for example, 0.7 μm. The reflecting surface  73   r  can be provided with the concavo-convex structure, or can also be provided with the structure in which the protrusions each shaped like a curved surface are arranged periodically. The rest of the configuration of the light source device  150  is substantially the same as in the first embodiment. 
     Advantages of Fifth Embodiment 
     Also in the present embodiment, it is possible to obtain substantially the same advantages as in the first embodiment such as an advantage that it is possible to realize the light source device  150  which is high in extraction efficiency of the fluorescence Y, and is easy to obtain the fluorescence Y having the desired intensity. Further, similarly to the third embodiment, since the fluorescence Y 1  having been transmitted through the second face  50   b  is reflected in a scattered manner by the reflecting surface  73   r  formed of the rough surface to turn to the fluorescence Y 2  having the angle variously changed, it is possible to further increase the extraction efficiency of the fluorescence Y. 
     It should be noted that the scope of the present disclosure is not limited to the embodiments described above, and a variety of modifications can be provided thereto within the scope or the spirit of the present disclosure. Further, one aspect of the present disclosure can be provided with a configuration obtained by arbitrarily combining characterizing portions of the respective embodiments described above with each other. 
     Further, the specific descriptions of the shape, the number, the arrangement, the material, and so on of the constituents of the light source device and the projector are not limited to those in the embodiments described above, and can arbitrarily be modified. Further, although in the embodiments described above, there is described the example of installing the light source device according to the present disclosure in the projector using the liquid crystal panels, the example is not a limitation. The light source device according to the present disclosure can also be applied to a projector using digital micromirror devices as the light modulation devices. Further, the projector is not required to have a plurality of light modulation devices, and can be provided with just one light modulation device. 
     Although in the embodiments described above, there is described the example of applying the light source device according to the present disclosure to the projector, the example is not a limitation. The light source device according to the present disclosure can also be applied to lighting equipment, a headlight of a vehicle, and so on. 
     A light source device according to an aspect of the present disclosure may have the following configuration. 
     The light source device according to an aspect of the present disclosure includes a light emitting element having a light emitting surface configured to emit first light having a first wavelength band, a wavelength conversion member which includes a phosphor, and which is configured to convert the first light emitted from the light emitting element into second light having a second wavelength band different from the first wavelength band, and a reflecting member having a reflecting surface configured to reflect the second light generated by the wavelength conversion member, wherein the wavelength conversion member has a first face which crosses a longitudinal direction of the wavelength conversion member, and which emits the second light, a second face which crosses the longitudinal direction of the wavelength conversion member, and which is located at an opposite side to the first face, and a third face crossing the first face and the second face, the light emitting surface is disposed so as to be opposed to at least a part of the third face, the reflecting surface is disposed so as to be opposed to the second face, and at least one of the second face and the reflecting surface is a rough surface. 
     The light source device according to an aspect of the present disclosure can be provided with a configuration in which the second face is a rough surface, and the reflecting surface is a smooth surface. 
     The light source device according to an aspect of the present disclosure can be provided with a configuration in which the second face is a smooth surface, and the reflecting surface is a rough surface. 
     The light source device according to an aspect of the present disclosure can be provided with a configuration in which the reflecting surface has a concavo-convex structure. 
     The light source device according to an aspect of the present disclosure can be provided with a configuration in which the reflecting surface has a structure in which protrusions shaped like a curved surface are arranged periodically. 
     The light source device according to an aspect of the present disclosure can be provided with a configuration in which the reflecting member has a base disposed so as to be opposed to the second face, and a wall which continues from the base and is disposed so as to be opposed to a part of the third face. 
     The light source device according to an aspect of the present disclosure can be provided with a configuration in which there are further included an angle conversion member which is disposed so as to be opposed to the first face, and which is configured to convert an angle distribution of the second light emitted from the first face, and a bonding member disposed between the angle conversion member and the first face. 
     A projector according to an aspect of the present disclosure may have the following configuration. 
     The projector according to an aspect of the present disclosure includes the light source device according to the aspect of the present disclosure, a light modulation device configured to modulate light including the second light emitted from the light source device in accordance with image information, and a projection optical device configured to project the light modulated by the light modulation device.