Patent Publication Number: US-11656540-B2

Title: Illumination device and projector

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 17/258,887, filed 8 Jan. 2021, which is a national stage application under 35 U.S.C. 371 and claims the benefit of PCT Application No. PCT/JP2019/026114 having an international filing date of 1 Jul. 2019, which designated the United States, which PCT application claimed the benefit of Japanese Patent Application No. 2018-138366 filed 24 Jul. 2018, the entire disclosures of each of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to an illumination device and a projector that make it possible to achieve an HDR (High Dynamic Range). 
     BACKGROUND ART 
     In recent years, in the field of video display, techniques of enhancing a dynamic range have been proposed, and particularly an HDR standard has attracted attention. The HDR standard is a video signal format that expands gradation representation of a low luminance part and achieves high peak luminance. The former signal format has allowed for luminance representation up to about 100 cd/m 2 . Meanwhile, however, there has currently been a growing demand for several tenfold higher luminance representation. PTL 1 proposes a technique of enhancing the dynamic range, in an illumination device of a projector, by causing HDR light and SDR (Standard Dynamic Range) light to enter an integrator optical system for multiplexing. 
     CITATION LIST 
     Patent Literature 
     PTL 1: International Publication No. WO2018/025506 
     SUMMARY OF THE INVENTION 
     However, when multiplexing the HDR light and the SDR light in order to enhance the dynamic range, light utilization efficiency may be decreased. 
     It is desirable to provide an illumination device and a projector that achieve a high dynamic range and suppress a decrease in light utilization efficiency. 
     Means for Solving the Problem 
     An illumination device according to an embodiment of the present disclosure includes: a first light source unit that emits first light of a first wavelength band; a first spatial light modulator where the first light from the first light source unit enters; a second light source unit that emits second light of a second wavelength band; an integrator optical system including a first fly-eye lens where the second light from the second light source unit enters and generating illumination light for an illumination target on a basis of the first light having been modulated by the first spatial light modulator and on a basis of the second light from the second light source unit; and a multiplexing optical system that multiplexes the second light having entered the first fly-eye lens and the first light having been modulated by the first spatial light modulator, in an optical path between the first fly-eye lens and the illumination target. 
     A projector according to an embodiment of the present disclosure includes: an illumination device including a first spatial light modulator where first light of a first wavelength band enters; and a second spatial light modulator that modulates illumination light from the illumination device to generate a projection image on a basis of an image signal, in which the illumination device further includes a first light source unit that emits the first light of the first wavelength band, a second light source unit that emits second light of a second wavelength band, an integrator optical system including a first fly-eye lens where the second light from the second light source unit enters and generating illumination light for the second spatial light modulator on a basis of the first light having been modulated by the first spatial light modulator and on a basis of the second light from the second light source unit, and a multiplexing optical system that multiplexes the second light having entered the first fly-eye lens and the first light having been modulated by the first spatial light modulator, in an optical path between the first fly-eye lens and the illumination target. 
     In the illumination device or the projector according to respective embodiments of the present disclosure, the first light having been modulated by the first spatial light modulator and the second light having entered the first fly-eye lens of the integrator optical system are multiplexed in the optical path between the first fly-eye lens and the illumination target. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a configuration diagram schematically illustrating a configuration example of a projector according to a first embodiment of the present disclosure. 
         FIG.  2    is a characteristic diagram illustrating an example of spectral characteristics of first light of a first wavelength band and second light of a second wavelength band in the projector according to the first embodiment. 
         FIG.  3    is a configuration diagram schematically illustrating a configuration example of a first light source unit in the projector according to the first embodiment. 
         FIG.  4    is a plan view schematically illustrating a configuration example of a multiplexing mirror in the projector according to the first embodiment. 
         FIG.  5    is a characteristic diagram illustrating an example of reflection characteristics of the multiplexing mirror in the projector according to the first embodiment. 
         FIG.  6    is an explanatory diagram illustrating a passing state of a light ray passing through a first fly-eye lens and a second fly-eye lens in the projector according to the first embodiment. 
         FIG.  7    is a block diagram schematically illustrating a configuration example of a main part of a control unit of the projector according to the first embodiment. 
         FIG.  8    is a configuration diagram schematically illustrating a configuration example of a main part of a projector according to a modification example of the first embodiment. 
         FIG.  9    is a plan view schematically illustrating a configuration example of a multiplexing mirror in the projector according to the modification example of the first embodiment. 
         FIG.  10    is a configuration diagram illustrating an overview of a projector according to a first comparative example with respect to the projector according to the first embodiment. 
         FIG.  11    is a configuration diagram illustrating an overview of a projector according to a second comparative example with respect to the projector according to the first embodiment. 
         FIG.  12    is a configuration diagram schematically illustrating a configuration example of a main part of a projector according to a second embodiment. 
         FIG.  13    is a plan view schematically illustrating a configuration example of a multiplexing mirror in the projector according to the second embodiment. 
         FIG.  14    is a configuration diagram schematically illustrating a configuration example of a main part of a projector according to a first modification example of the second embodiment. 
         FIG.  15    is a configuration diagram schematically illustrating a configuration example of a main part of a projector according to a second modification example of the second embodiment. 
         FIG.  16    is a plan view schematically illustrating a configuration example of a multiplexing mirror in the projector according to the second modification example of the second embodiment. 
         FIG.  17    is a configuration diagram schematically illustrating a configuration example of a projector according to a third embodiment. 
         FIG.  18    is a configuration diagram schematically illustrating a configuration example of a projector according to a fourth embodiment. 
         FIG.  19    is a configuration diagram schematically illustrating a configuration example of a projector according to a fifth embodiment. 
         FIG.  20    is a configuration diagram schematically illustrating a configuration example of a main part of a projector according to a first modification example of the fifth embodiment. 
         FIG.  21    is a plan view schematically illustrating a configuration example of a multiplexing mirror in the projector according to the first modification example of the fifth embodiment. 
         FIG.  22    is a plan view schematically illustrating a configuration example of a multiplexing mirror in a projector according to a second modification example of the fifth embodiment. 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     Hereinafter, description is given in detail of embodiments of the present disclosure with reference to the drawings. It is to be noted that the description is given in the following order.
     1. First Embodiment ( FIGS.  1  to  11   )
       1.1 Configuration and Operation of Illumination Device and Projector according to First Embodiment
           1.1.1 Configuration and Operation of Entire Projector   1.1.2 Configuration and Operation of Each Component of Projector   
           1.2 Effects and Comparative Examples   
       2. Second Embodiment ( FIGS.  12  to  16   )   3. Third Embodiment ( FIG.  17   )   4. Fourth Embodiment ( FIG.  18   )   5. Fifth Embodiment ( FIGS.  19  to  22   )   6. Other Embodiments   

     1. FIRST EMBODIMENT 
     1.1 Configuration and Operation of Illumination Device and Projector According to First Embodiment 
     [1.1.1 Configuration and Operation of Entire Projector] 
       FIG.  1    schematically illustrates a configuration example of a projector  1  according to a first embodiment of the present disclosure. It is to be noted that description is given, in the first embodiment, by exemplifying a case of monochromatic display for simplicity of the description. 
     The projector  1  according to the first embodiment is, for example, a display apparatus that projects an image on a screen  19 . The projector  1  is coupled, for example, to a computer such as a PC (personal computer) or an external image supply apparatus such as various image players via an I/F (interface), and performs projection onto the screen  19  on the basis of an image signal VS inputted to the I/F. It is to be noted that the configuration of the projector  1  described below is merely an example, and the projector of the present technology is not limited to such a configuration. 
     The projector  1  includes an illumination device provided with a first spatial light modulator  13 , and a second spatial light modulator  16  that modulates illumination light from the illumination device to generate a projection image on the basis of the image signal VS. The second spatial light modulator  16  is an illumination target to be illuminated by the illuminating device. The projector  1  further includes a projection optical system  17  that projects the projection image generated by the second spatial light modulator  16  onto a projection plane, such as the screen  19 , and a control unit  30  that controls the illumination device, the second spatial light modulator  16  and the projection optical system  17 . 
     The illumination device includes a first light source unit  11 , a first illumination optical system  12 A, a second illumination optical system  12 B, a first spatial light modulator  13 , a second light source unit  14 , a third illumination optical system  15 , an integrator optical system  20 , and a multiplexing optical system  50 . 
     It is to be noted that, in  FIG.  1   , for example, an optical axis direction of the integrator optical system  20  is defined as a Z-direction. In addition, one direction orthogonal to the Z-direction is defined as an X-direction. In addition, a direction orthogonal to the Z-direction and the X-direction is defined as a Y-direction. The same applies to other subsequent drawings. 
     The integrator optical system  20  includes a pair of fly-eye lenses (a first fly-eye lens  21 A and a second fly-eye lens  21 B), a polarization conversion element  23 , and a fourth illumination optical system  22 . 
     The multiplexing optical system  50  includes a multiplexing lens  51  and a multiplexing mirror  52 . 
     For example, an HDR signal is inputted as the image signal VS to the projector  1 . The projector  1  divides the HDR signal into a signal of a high luminance region and a signal of a low luminance region, and generates an image of a high luminance region using at least HDR light L H2  and generates an image of a low luminance region using at least SDR light L S , out of the projection image generated in the second spatial light modulator  16 . The HDR light L H2  is generated by causing the first spatial light modulator  13  to modulate HDR light L H1  from the first light source unit  11 . This makes it possible to achieve a high dynamic range in a high luminance region and to suppress a decrease in light utilization efficiency in a portion other than the high luminance region. 
     The HDR light L H2  from the first spatial light modulator  13  and the SDR light L S  from the second light source unit  14  are multiplexed by the multiplexing optical system  50  and the integrator optical system  20  to generate integrated light (synthesized light) L HS . The second spatial light modulator  16  is irradiated with the integrated light L HS , as illumination light, including the HDR light L H2  and the SDR light L S . 
     [1.1.2 Configuration and Operation of Each Component of Projector] 
     The first light source unit  11  and the second light source unit  14  each include, for example, a solid-state light source such as a semiconducting laser (LD) or a light-emitting diode. The first light source unit  11  and the second light source unit  14  may each be configured by a light source using a wavelength conversion material such as a phosphor, or may be configured by a discharge lamp. Each of the first light source unit  11  and the second light source unit  14  may be configured by one solid-state light source, or may be configured by a plurality of solid-state light sources. 
     The first light source unit  11  emits the HDR light L H1  as first light of a first wavelength band. The second light source unit  14  emits the SDR light L S  as second light of a second wavelength band. 
       FIG.  2    illustrates an example of spectral characteristics of the first light (HDR light L H1 ) of the first wavelength band and the second light (SDR light L S ) of the second wavelength band. As illustrated in  FIG.  2   , the first wavelength band is a band narrower than the second wavelength band. The second wavelength band includes the first wavelength band, and is a band wider than the first wavelength band. 
       FIG.  3    schematically illustrates a configuration example of the first light source unit  11 . As illustrated in  FIG.  3   , the first light source unit  11  may be configured to include an array light source  110  including a plurality of excitation light sources  111 , an excitation optical system  112 , and a wavelength conversion section  113 . The wavelength conversion section  113  includes a wavelength conversion material that enables wavelength conversion of a narrow band such as QD (quantum dot). Using a blue laser as the excitation light source  111  allows for better cost efficiency. In addition, adopting the array light source  110  with arrayed blue lasers and using the excitation optical system  112  make it possible to achieve higher luminance of the first light source unit  11 . 
     The first illumination optical system  12 A is an optical system for guiding the HDR light L H1  emitted from the first light source unit  11  to the first spatial light modulator  13 . The first illumination optical system  12 A is configured by, for example, a plurality of lenses or a single lens, etc. The first illumination optical system  12 A is provided on an optical path between the first light source unit  11  and the first spatial light modulator  13 . 
     The first spatial light modulator  13  performs intensity modulation or phase modulation of incident light. The first spatial light modulator  13  is configured by, for example, a transmissive liquid crystal panel. It is to be noted that the first spatial light modulator  13  may be configured by a reflective liquid crystal panel or a mirror device using a micromirror. 
     The HDR light L H1  from the first light source unit  11  enters the first spatial light modulator  13  via the first illumination optical system  12 A. The first spatial light modulator  13  modulates the HDR light L H1  from the first light source unit  11  on the basis of a signal of a high luminance region included in the image signal VS. The first spatial light modulator  13  is provided on an optical path between the first illumination optical system  12 A and the second illumination optical system  12 B. 
     The second illumination optical system  12 B is an optical system for guiding the HDR light L H2  having been modulated by the first spatial light modulator  13  to the multiplexing optical system  50 . The second illumination optical system  12 B is configured by, for example, a plurality of lenses or a single lens. 
     The third illumination optical system  15  is an optical system for collimating the SDR light L S  emitted from the second light source unit  14  and guiding the collimated SDR light L S  to the integrator optical system  20 . The third illumination optical system  15  is configured by, for example, a plurality of lenses or a single lens. The third illumination optical system  15  is provided on an optical path between the second light source unit  14  and the first fly-eye lens  21 A of the integrator optical system  20 . 
     The integrator optical system  20  generates illumination light for the second spatial light modulator  16  on the basis of the HDR light L H2  having been modulated by the first spatial light modulator  13  and the SDR light L S  emitted from the second light source unit  14 . The second spatial light modulator  16  is irradiated with synthesized light (integrated light L HS ), as illumination light, of the HDR light L H2  and the SDR light L S  generated by the multiplexing optical system  50  and the integrator optical system  20 . 
     In the integrator optical system  20 , each of the first fly-eye lens  21 A and the second fly-eye lens  21 B is configured by a plurality of lens elements. A focal distance of each lens element of the first fly-eye lens  21 A and a focal distance of each lens element of the second fly-eye lens  21 B are substantially equal to each other. A distance between the first fly-eye lens  21 A and the second fly-eye lens  21 B is the same as a value of the focal distance, for example. The distance between the first fly-eye lens  21 A and the second fly-eye lens  21 B may be a value near the value of the focal distance. The second fly-eye lens  21 B is provided on an optical path between the first fly-eye lens  21 A and the second spatial light modulator  16 , and more particularly between the first fly-eye lens  21 A and the polarization conversion element  23 . 
     The polarization conversion element  23  is a P-S polarization conversion element that converts incident light into specific linearly polarized light (e.g., P-polarized light or S-polarized light). The polarization conversion element  23  is provided on an optical path between the second fly-eye lens  21 B and the second spatial light modulator  16 , and more particularly between the second fly-eye lens  21 B and the fourth illumination optical system  22 . 
     The fourth illumination optical system  22  is provided for guiding the synthesized light (integrated light L HS ) of the HDR light L H2  and the SDR light L S  to the second spatial light modulator  16 . The fourth illumination optical system  22  is provided on an optical path between the polarization conversion element  23  and the second spatial light modulator  16 . 
     The SDR light L S  emitted from the second light source unit  14  passes through the third illumination optical system  15 , for example, and thereafter enters the first fly-eye lens  21 A. The SDR light L S  is uniformized together with the HDR light L H2  in the integrator optical system  20 , and is irradiated to the second spatial light modulator  16 . 
     The second spatial light modulator  16  is configured by, for example, a transmissive liquid crystal panel that enables intensity modulation of incident light. The second spatial light modulator  16  modulates the illumination light (integrated light L HS ) from the integrator optical system  20  on the basis of the image signal VS to generate a projection image. The second spatial light modulator  16  is provided on an optical path between the integrator optical system  20  and the projection optical system  17 . It is to be noted that the second spatial light modulator  16  may be configured by a reflective liquid crystal panel or a mirror device using a micromirror. 
     The projection optical system  17  enlarges and projects the projection image generated by the second spatial light modulator  16  onto a projection plane such as the screen  19 . The projection optical system  17  is configured by, for example, a plurality of lenses or a single lens. 
     Configuration Example of Multiplexing Optical System  50   
       FIG.  4    schematically illustrates a configuration example of the multiplexing mirror  52  in the multiplexing optical system  50 .  FIG.  5    illustrates an example of reflection characteristics of the multiplexing mirror  52 .  FIG.  6    illustrates a passing state of a light ray passing through the first fly-eye lens  21 A and the second fly-eye lens  21 B in the integrator optical system  20 . 
     The multiplexing optical system  50  is provided for multiplexing the SDR light L S  having entered the first fly-eye lens  21 A in the integrator optical system  20  and the HDR light L H2  having been modulated by the first spatial light modulator  13 , in the optical path between the first fly-eye lens  21 A and the second spatial light modulator  16 . In the projector  1  according to the first embodiment, the multiplexing optical system  50  multiplexes the SDR light L S  having entered the first fly-eye lens  21 A and the HDR light L H2  having been modulated by the first spatial light modulator  13 , in an optical path between the first fly-eye lens  21 A and the second fly-eye lens  21 B in the integrator optical system  20 . 
     The multiplexing optical system  50  includes the multiplexing lens  51  that causes the HDR light L H2  having been modulated by the first spatial light modulator  13  to enter the optical path between the first fly-eye lens  21 A in the integrator optical system  20  and the second spatial light modulator  16 . In the projector  1  according to the first embodiment, the multiplexing lens  51  causes the HDR light L H2  having been modulated by the first spatial light modulator  13  to enter the optical path between the first fly-eye lens  21 A and the second fly-eye lens  21 B in the integrator optical system  20 . The multiplexing lens  51  is provided on an optical path between the second illumination optical system  12 B and the multiplexing mirror  52 . 
     The multiplexing lens  51  includes one lens element corresponding to at least one lens element in the first fly-eye lens  21 A in the integrator optical system  20 , and is configured to be paired with at least one lens element in the second fly-eye lens  21 B. 
     The multiplexing optical system  50  includes at least one multiplexing mirror  52  disposed in the optical path between the first fly-eye lens  21 A and the second spatial light modulator  16 . In the projector  1  according to the first embodiment, the multiplexing mirror  52  is provided on the optical path between the first fly-eye lens  21 A and the second fly-eye lens  21 B in the integrator optical system  20 . 
     The multiplexing mirror  52  includes at least one reflection part  60  that reflects the HDR light L H2  having been modulated by the first spatial light modulator  13 . The multiplexing mirror  52  has a structure in which, for example, a region on which at least the HDR light L H2  is incident (a part to be multiplexed with the SDR light L S ) functions as a reflective element to the HDR light L H2 , and the other region has a function of transmitting the SDR light L S . For example, as illustrated in  FIG.  4   , the multiplexing mirror  52  has a structure in which a reflective coating is applied as the reflection part  60  to a region, on a substrate that transmits at least the SDR light L S , on which at least the HDR light L H2  is incident. It is to be noted that the multiplexing mirror  52  may be a reflective mirror of a structure of only a part corresponding to the reflection part  60 . 
     In a case where the HDR light L H2  of the first wavelength band and the SDR light L S  of the second wavelength band have respective spectral characteristics as illustrated in  FIG.  2   , it is desirable that the reflection part  60  in the multiplexing mirror  52  have a reflective function for the first wavelength band and a transmissive function for a band other than the first wavelength band in the second wavelength band, as in reflection characteristics illustrated in  FIG.  5   . This allows the SDR light L S  of a wavelength portion different from that of the HDR light L H2  to be transmitted through the reflection part  60 , thus making it possible to achieve higher efficiency of the SDR light L S . 
     Here, as illustrated in  FIG.  6   , light entering the first fly-eye lens  21 A has a light flux diameter that becomes smaller as the light travels toward a subsequent stage (side of the second fly-eye lens  21 B), between the first fly-eye lens  21 A and the second fly-eye lens  21 B. Therefore, positioning the reflection part  60  on side close to the second fly-eye lens  21 B (side of smaller light flux diameter) between the first fly-eye lens  21 A and the second fly-eye lens  21 B increases a degree of design freedom of the multiplexing mirror  52  and makes it easier to prevent a decrease in light efficiency, which is thus preferable. 
     Configuration Example of Control Unit  30   
       FIG.  7    schematically illustrates a configuration example of a main part of the control unit  30 . 
     As illustrated in  FIG.  7   , the control unit  30  includes, for example, a signal distribution circuit  31 , an HDR signal circuit  32 , an intensity modulation calculation circuit  33 , and an intensity modulation signal circuit  34 . 
     For example, an HDR signal including a signal VS H  of a high luminance region is inputted as the image signal VS to the signal distribution circuit  31 . The signal distribution circuit  31  distributes the image signal VS into the signal VS H  of the high luminance region and another signal VS S . Of the image signal VS, the signal VS H  of the high luminance region is sent to the HDR signal circuit  32 . The other signal VS S  is sent to the intensity modulation calculation circuit  33 . The other signal VS S  includes information for the second spatial light modulator  16  to generate an image based on the image signal VS in consideration of the signal VS H  of the high luminance region. 
     The HDR signal circuit  32  generates a drive signal for driving the first spatial light modulator  13  on the basis of the signal VS H  of the high luminance region from the signal distribution circuit  31 . This cause the first spatial light modulator  13  to be driven by a drive signal based on the signal VS H  of the high luminance region and to modulate the HDR light L H1  from the first light source unit  11  to generate the HDR light L H2  corresponding to the image of the high luminance region. 
     The intensity modulation calculation circuit  33  calculates a signal to be sent to the intensity modulation signal circuit  34  on the basis of the signal VS S  from the signal distribution circuit  31 , a light emission state of the second light source unit  14 , and the like. The intensity modulation signal circuit  34  generates a drive signal for driving the second spatial light modulator  16  on the basis of the signal sent from the intensity modulation calculation circuit  33 . This allows the second spatial light modulator  16  to generate an image of the low luminance region using at least the SDR light L S  as a portion of the projection image. Meanwhile, as described above, the second spatial light modulator  16  is irradiated with the synthesized light (integrated light L HS ) of the HDR light L H2  and the SDR light L S , and thus the projection image generated by the second spatial light modulator  16  also includes an image of the high luminance region. This allows for generation of a projection image with a high dynamic range. 
     Additionally, the control unit  30  may include a light source control section for controlling the first light source unit  11  and the second light source unit  14 . In addition, the control unit  30  may include, for example, a lens control section or the like that controls a lens position or the like inside the projection optical system  17 . 
     Modification Example of First Embodiment 
       FIG.  8    schematically illustrates a configuration example of a main part of a projector  1 A according to a modification example of the first embodiment.  FIG.  9    schematically illustrates a configuration example of a multiplexing mirror  52 A in the projector  1 A according to the modification example of the first embodiment. 
     The projector  1 A according to the present modification example includes a multiplexing optical system  50 A instead of the multiplexing optical system  50  in the projector  1  according to the first embodiment. 
     The multiplexing optical system  50 A in the modification example includes a multiplexing fly-eye lens  51 A and the multiplexing mirror  52 A. 
     In the projector  1  according to the first embodiment, as illustrated in  FIGS.  1  and  4   , the multiplexing lens  51  includes, in the multiplexing optical system  50 , one lens element corresponding to one lens element in the first fly-eye lens  21 A in the integrator optical system  20 , for example. In addition, as illustrated in  FIG.  4   , the multiplexing mirror  52  includes the one reflection part  60 , and the multiplexing mirror  52  is disposed to allow the one reflection part  60  to be positioned at a part corresponding to an optical path of the one lens element in the first fly-eye lens  21 A in the integrator optical system  20 . 
     In contrast, the multiplexing optical system  50 A in the modification example includes the multiplexing fly-eye lens  51 A corresponding to the plurality of lens elements in the first fly-eye lens  21 A. This allows the multiplexing fly-eye lens  51 A to generate HDR light beams L H21 , L H22 , and L H23 , i.e., a plurality of light fluxes divided from the incident HDR light L H2 . It is to be noted that  FIG.  8    exemplifies an example in which the multiplexing fly-eye lens  51 A includes three lens elements and the light flux of the HDR light L H2  is divided into three; however, the number of lens elements of the multiplexing fly-eye lens  51 A and the number of divisions of the light fluxes may be each two. In addition, the number of the lens elements of the multiplexing fly-eye lens  51 A and the number of divisions of the light fluxes may be each four or more. 
     The multiplexing mirror  52 A has a plurality of reflection parts  61 ,  62 , and  63  according to the number of divisions of the light fluxes divided by the multiplexing fly-eye lens  51 A. The multiplexing mirror  52 A is disposed to allow the plurality of reflection parts  61 ,  62 , and  63  to be positioned on respective optical paths of the plurality of HDR light beams L H21 , L H22 , and L H23  generated by the multiplexing fly-eye lens  51 A. The plurality of reflection parts  61 ,  62 , and  63  reflect, respectively, the plurality of HDR light beams L H21 , L H22 , and L H23  generated by the multiplexing fly-eye lens  51 A toward a plurality of lens elements of the second fly-eye lens  21 B. The structure and reflection characteristics of each of the plurality of reflection parts  61 ,  62 , and  63  are substantially similar to those of the reflection part  60  in the multiplexing optical system  50 . It is to be noted that the plurality of HDR light beams L H21 , L H22 , and L H23  generated by the multiplexing fly-eye lens  51 A are incident on the multiplexing mirror  52 A at different positions in the Z-direction with respect to an optical axis Z 1  of the integrator optical system  20 . For this reason, the light flux diameters of the plurality of HDR light beams L H21 , L H22 , and L H23  that are incident on the multiplexing mirror  52 A are of different respective sizes depending on positions of incidence. The sizes of the plurality of reflection parts  61 ,  62 , and  63  are sizes corresponding to the light flux diameters of the plurality of HDR light beams L H21 , L H22 , and L H23  that are incident on the multiplexing mirror  52 A, and thus are sizes different from each other. It is to be noted that optical path lengths of respective optical paths of the plurality of HDR light beams L H21 , L H22 , and L H23  from the multiplexing fly-eye lens  51 A through the multiplexing mirror  52 A to the second fly-eye lens  21 B are substantially the same as each other. However, the optical path lengths of these optical paths may be different from each other. 
     It is possible, for the projector  1 A according to the present the modification example, to multiplex the plurality of HDR light beams L H21 , L H22 , and L H23  and the SDR light L S , in a plurality of optical paths between the first fly-eye lens  21 A and the second fly-eye lens  21 B of the integrator optical system  20 . 
     Other configurations and operations are substantially similar to those of the projector  1  according to the first embodiment. 
     1.2 Effects and Comparative Examples 
     As described above, according to the projector  1  according to the first embodiment, the first light (HDR light L H2 ) having been modulated by the first spatial light modulator  13  and the second light (SDR light L S ) having entered the first fly-eye lens of the integrator optical system are multiplexed in the optical path between the first fly-eye lens  21 A and the second spatial light modulator  16  as the illumination target, thus making it possible to achieve a high dynamic range and to suppress a decrease in the light utilization efficiency. 
     According to the projector  1  of the first embodiment, the HDR light L H2  and the SDR light L S  are multiplexed on the optical path of the lens element at the central part instead of the lens element at the periphery of the first fly-eye lens  21 A, as compared with a first comparative example ( FIG.  10   ) described later, thereby making it possible to improve optical efficiency of the HDR light L H2 , which, in other words, leads to an improvement in power efficiency. 
     In addition, according to the projector  1  of the first embodiment, the HDR light L H2  in a narrow band and the SDR light L S  in a band wider than the HDR light L H2  are multiplexed to generate the projection image, thus leading to an improvement in image quality. For example, it is possible to display an image based on the HDR signal only by the HDR light L H2  using only a highly coherent light source such as a laser. In this case, there is a possibility that the optical efficiency and the power efficiency may be higher than the case of generating a projection image through the division into the HDR light L H2  and the SDR light L S , in some occasions. However, using only the highly coherent light source having an extremely narrow wavelength band and high directivity, as in the laser, produces a speckle, resulting in poor image quality. Meanwhile, using a light source having a wide wavelength band such as fluorescence as the SDR light L S  reduces an influence of the speckle, making the speckle less likely to be visually recognized when generating and projecting a projection image by multiplexing the HDR light L H2  and the SDR light L S . This makes it possible to achieve an improvement in the image quality. 
     In addition, by using, as the first light source unit  11  that emits the HDR light L H1 , the excitation light source  111  such as a blue laser and the wavelength conversion element (wavelength conversion section  113 ) as illustrated in  FIG.  3   , it is possible to achieve high cost efficiency. Although it may be possible to achieve the HDR light L H2  and the SDR light L S  by using only a laser, as for green and red lasers, EO efficiency is low and the unit price is high, thus causing higher costs. Achieving an optical configuration in which a blue laser is used as the excitation light source  111  and wavelength conversion is adopted to facilitate use of green light and red light allows for better cost efficiency. 
     Projectors According to Comparative Examples 
     Description is given here, as a comparative example, of a configuration of a projector corresponding to a technique disclosed in PTL 1 (WO2018/025506). 
       FIG.  10    illustrates an overview of a projector  101  according to a first comparative example with respect to the projector  1  according to the first embodiment.  FIG.  11    illustrates an overview of a projector  101 A according to a second comparative example with respect to the projector  1  according to the first embodiment. It is to be noted that, in the following, components substantially the same as those of the illumination device and the projector  1  according to the foregoing first embodiment are denoted by the same reference numerals, and the description thereof is omitted where appropriate. 
     The projector  101  according to the first comparative example and the projector  101 A according to the second comparative example are each provided with an optical path conversion element  12 C instead of the multiplexing optical system  50  in the projector  1  according to the first embodiment. The optical path conversion element  12 C is configured by a mirror, or the like, for example. 
     In the projectors  101  and  101 A according to the first and second comparative examples, the optical path conversion element  12 C is disposed at a stage preceding the first fly-eye lens  21 A in the integrator optical system  20 , and the HDR light L H2  having been modulated by the first spatial light modulator  13  is caused to enter the first fly-eye lens  21 A to thereby multiplex the HDR light L H2  and the SDR light L S  from the second light source unit  14  in the integrator optical system  20 . 
     In the projector  101  according to the first comparative example illustrated in  FIG.  10   , the optical path conversion element  12 C causes the HDR light L H2  to enter an outermost lens element of the first fly-eye lens  21 A in order to prevent a decrease in the efficiency of the SDR light L S . In the case of this configuration, there is a drop in a peripheral light amount in the integrator optical system  20  and the projection optical system  17 , thus leading to deteriorated optical efficiency of the HDR light L H2 . In particular, in a case of using, as the projection optical system  17 , a projection lens with a large drop in the peripheral light amount such as an ultrashort focal lens, light in each of the peripheries of the first fly-eye lens  21 A and the second fly-eye lens  21 B may substantially discarded, or luminance unevenness and chromaticity unevenness may occur significantly in a projection image in some occasions. 
     In contrast, disposing the optical path conversion element  12 C in the vicinity of the center of the first fly-eye lens  21 A as in the projector  101 A according to the second comparative example illustrated in  FIG.  11    allows the HDR light L H2  and the SDR light L S  to be multiplexed in the vicinity of the center of the first fly-eye lens  21 A, which makes it possible to prevent a drop in the peripheral light amount of the HDR light L H2 . However, the optical path conversion element  12 C and the structural part holding the optical path conversion element  12 C block light passing through the vicinity of the center of the SDR light L S  from the second light source unit  14 , thus leading to a decrease in the efficiency of the SDR light L S . 
     In addition, in both of the projectors  101  and  101 A according to the first and second comparative examples, the size of the optical path conversion element  12 C needs to be substantially similar to that of a light flux entering at least one of lens elements of the first fly-eye lens  21 A. In contrast, in the projector  1  according to the first embodiment, as illustrated in  FIGS.  1  and  6   , the reflection part  60  of the multiplexing mirror  52  is able to be positioned at a position where the light flux diameter becomes smaller between the first fly-eye lens  21 A and the second fly-eye lens  21 B, thus enabling the reflection part  60  to be configured to be smaller than the optical path conversion element  12 C in the first and second comparative examples. 
     It is to be noted that the effects described herein are merely illustrative and non-limiting, and may have other effects. The same applies to the effects of the following other embodiments. 
     2. SECOND EMBODIMENT 
     Next, description is given of an illumination device and a projector according to a second embodiment of the present disclosure. It is to be noted that, in the following, substantially the same components as those of the illumination device and the projector according to the foregoing first embodiment are denoted by the same reference numerals, and description thereof is omitted where appropriate. 
     In the second embodiment, description is given of an illumination device and a projector corresponding to color display. 
       FIG.  12    schematically illustrates a configuration example of a main part of a projector  1 B according to the second embodiment.  FIG.  13    schematically illustrates a configuration example of a multiplexing mirror  52 B in the projector  1 B according to the second embodiment. 
     The projector  1 B according to the second embodiment includes a multiplexing optical system  50 B instead of the multiplexing optical system  50  in the projector  1  according to the first embodiment. 
     The multiplexing optical system  50 B in the projector  1 B includes the multiplexing fly-eye lens  51 A and the multiplexing mirror  52 B. 
     The multiplexing optical system  50 B includes the multiplexing fly-eye lens  51 A corresponding to the plurality of lens elements in the first fly-eye lens  21 A, substantially similarly to the projector  1 A ( FIGS.  8  and  9   ) according to the modification example of the first embodiment. The HDR light L H2  including a plurality of color light beams (a red HDR light L HR , a green HDR light L HG , and a blue HDR light L HB ) enters the multiplexing optical system  50 B. Mutually different color light beams (red HDR light L HR , green HDR light L HG , and blue HDR light L HB ) enter the respective lens elements of the multiplexing fly-eye lens  51 A. 
     The multiplexing mirror  52 B includes a plurality of reflection parts (a red reflection part  61 R, a green reflection part  62 G, and a blue reflection part  63 B) that reflect respective color light beams having been modulated by the first spatial light modulator  13  at spatially different positions for respective colors. The multiplexing mirror  52 B is disposed to allow the red reflection part  61 R, the green reflection part  62 G, and the blue reflection part  63 B to be positioned on respective optical paths of the red HDR light L HR , the green HDR light L HG , and the blue HDR light L HB  from the multiplexing fly-eye lens  51 A. The red reflection part  61 R, the green reflection part  62 G, and the blue reflection part  63 B reflect, respectively, the red HDR light L HR , the green HDR light L HG , and the blue HDR light L HB  from the multiplexing fly-eye lens  51 A toward a plurality of lens elements of the second fly-eye lens  21 B. 
     As illustrated in  FIG.  13   , the multiplexing mirror  52 B has a structure in which, for example, reflective coatings that reflect respective color light beams are applied, as the red reflection part  61 R, the green reflection part  62 G, and the blue reflection part  63 B, to a region, on the substrate that transmits at least the SDR light L S , on which at least the red HDR light L HR , the green HDR light L HG , and the blue HDR light L HB  are incident. 
     It is to be noted that the red HDR light L HR , the green HDR light L HG , and the blue HDR light L HB  from the multiplexing fly-eye lens  51 A are incident on the multiplexing mirror  52 B at spatially different positions in the Z-direction with respect to the optical axis Z 1  of the integrator optical system  20 . For this reason, the light flux diameters of respective color light beams that are incident on the multiplexing mirror  52 B are of different respective sizes depending on positions of incidence. The sizes of the red reflection part  61 R, the green reflection part  62 G, and the blue reflection part  63 B correspond to the light flux diameters of the respective color light beams incident on the multiplexing mirror  52 B, and thus are sizes different from each other. It is to be noted that the optical path lengths of optical paths of the respective color light beams from the multiplexing fly-eye lens  51 A through the multiplexing mirror  52 B to the second fly-eye lens  21 B are substantially the same as each other. However, the optical path lengths of these optical paths may be different from each other. 
     In this manner, in the multiplexing optical system  50 B, the respective color light beams having been modulated by the first spatial light modulator  13  are multiplexed with the SDR light L S  having entered the first fly-eye lens  21 A at mutually different positions in the optical path between the first fly-eye lens  21 A and the second spatial light modulator  16 . 
     Other configurations, operations, and effects may be substantially similar to those of the illumination device and the projector  1 B according to the foregoing first embodiment. 
     First Modification Example of Second Embodiment 
       FIG.  14    schematically illustrates a configuration example of a main part of a projector  1 C according to a first modification example of the second embodiment. 
     The projector  1 C according to the first modification example includes a multiplexing optical system  50 C instead of the multiplexing optical system  50 B in the projector  1 B according to the second embodiment. 
     The multiplexing optical system  50 C in the first modification example includes a plurality of multiplexing mirrors (a red multiplexing mirror  53 R, a green multiplexing mirror  53 G, and a blue multiplexing mirror  53 B) that reflect respective color light beams, instead of the multiplexing mirror  52 B in the multiplexing optical system  50 B. 
     The red multiplexing mirror  53 R, the green multiplexing mirror  53 G, and the blue multiplexing mirror  53 B has respective sizes corresponding to the red reflection part  61 R, the green reflection part  62 G, and the blue reflection part  63 B in the multiplexing optical system  50 B. In addition, the red multiplexing mirror  53 R, the green multiplexing mirror  53 G, and the blue multiplexing mirror  53 B are disposed, respectively, at positions corresponding to the red reflection part  61 R, the green reflection part  62 G, and the blue reflection part  63 B in the multiplexing optical system  50 B. 
     The red multiplexing mirror  53 R, the green multiplexing mirror  53 G, and the blue multiplexing mirror  53 B may be each configured by a reflective mirror or a dichroic mirror that reflects each incident color light beam. 
     Other configurations, operations, and effects may be substantially similar to those of the illumination device and the projector  1 B according to the foregoing second embodiment. 
     Second Modification Example of Second Embodiment 
       FIG.  15    schematically illustrates a configuration example of a main part of a projector  1 D according to a second modification example of the second embodiment.  FIG.  16    schematically illustrates a configuration example of a multiplexing mirror  52 D in the projector  1 D according to the second modification example of the second embodiment. 
     The projector  1 D according to the second modification example includes a multiplexing optical system  50 D instead of the multiplexing optical system  50 B in the projector  1 B according to the second embodiment. 
     The multiplexing optical system  50 D in the second modification example includes the multiplexing mirror  52 D instead of the multiplexing mirror  52 B in the multiplexing optical system  50 B. 
     The plurality of color light beams (red HDR light L HR , green HDR light L HG , and blue HDR light L HB ) enter the multiplexing fly-eye lens  51 A of the multiplexing optical system  50 D in the second modification example from a direction different by 90° from that in the multiplexing optical system  50 B ( FIG.  12   ). That is, in the multiplexing fly-eye lens  51 A, a plurality of color light beams enter a plurality of lens elements (a red lens element  51 AR, a green lens element  51 AG, and a blue lens element  51 AB) aligned in a direction (X-direction) orthogonal to the optical axis Z 1  of the integrator optical system  20  in a Z-X plane in  FIG.  15   . 
     The multiplexing mirror  52 D includes a plurality of reflection parts (red reflection part  61 R, green reflection part  62 G, and blue reflection part  63 B) that reflect respective color light beams having been modulated by the first spatial light modulator  13  at spatially different positions for respective colors. The multiplexing mirror  52 D is disposed to allow the red reflection part  61 R, the green reflection part  62 G, and the blue reflection part  63 B to be positioned on respective optical paths of the red HDR light L HR , the green HDR light L HG , and the blue HDR light L HB  from the multiplexing fly-eye lens  51 A. The red reflection part  61 R, the green reflection part  62 G, and the blue reflection part  63 B reflect, respectively, the red HDR light L HR , the green HDR light L HG , and the blue HDR light L HB  from the multiplexing fly-eye lens  51 A toward a plurality of lens elements of the second fly-eye lens  21 B. 
     It is to be noted that, unlike the multiplexing mirror  52 B ( FIGS.  12  and  13   ), the red HDR light L HR , the green HDR light L HG , and the blue HDR light L HB  are incident on the multiplexing mirror  52 D of the second modification example at substantially the same position in the Z-direction with respect to the optical axis Z 1  of the integrator optical system  20 . For this reason, the light flux diameters of respective color light beams that are incident on the multiplexing mirror  52 D are of substantially the same size. The sizes of the red reflection part  61 R, the green reflection part  62 G, and the blue reflection part  63 B are sizes corresponding to the light flux diameters of the respective color light beams incident on the multiplexing mirror  52 D, and thus are sizes substantially the same as each other. It is to be noted that the optical path lengths of optical paths of the respective color light beams from the multiplexing fly-eye lens  51 A through the multiplexing mirror  52 D to the second fly-eye lens  21 B are substantially the same as each other. However, the optical path lengths of these optical paths may be different from each other 
     Other configurations, operations, and effects may be substantially similar to those of the illumination device and the projector  1 B according to the foregoing second embodiment. 
     3. THIRD EMBODIMENT 
     Next, description is given of an illumination device and a projector according to a third embodiment of the present disclosure. It is to be noted that, in the following, substantially the same components as those of the illumination device and the projector according to the foregoing first or second embodiment are denoted by the same reference numerals, and description thereof is omitted where appropriate. 
       FIG.  17    schematically illustrates a configuration example of a projector  1 E according to the third embodiment. 
     The projector  1 E according to the third embodiment includes a multiplexing optical system  50 E instead of the multiplexing optical system  50  in the projector  1  according to the first embodiment. 
     The multiplexing optical system  50 E multiplexes the SDR light L S  having entered the first fly-eye lens  21 A in the integrator optical system  20  and the HDR light L H2  having been modulated by the first spatial light modulator  13 , in an optical path between the second fly-eye lens  21 B and the second spatial light modulator  16 . More specifically, the multiplexing optical system  50 E multiplexes the SDR light L S  having entered the first fly-eye lens  21 A and the HDR light L H2  having been modulated by the first spatial light modulator  13 , in an optical path between the second fly-eye lens  21 B and the polarization conversion element  23  in the integrator optical system  20 . 
     The multiplexing optical system  50 E includes a pair of multiplexing fly-eye lenses (multiplexing fly-eye lenses  51 A and  51 B) corresponding to the pair of fly-eye lenses (first fly-eye lens  21 A and second fly-eye lens  21 B) in the integrator optical system  20 , instead of the multiplexing lens  51  of the multiplexing optical system  50  in the first embodiment. The multiplexing fly-eye lenses  51 A and  51 B cause the HDR light L H2  having been modulated by the first spatial light modulator  13  to enter the optical path between the second fly-eye lens  21 B and the polarization conversion element  23  in the integrator optical system  20 . 
     In addition, the multiplexing optical system  50 E includes the multiplexing mirror  52  having a structure similar to that of the multiplexing optical system  50  in the first embodiment. However, in the multiplexing optical system  50 E, the position where the multiplexing mirror  52  is disposed is different from that of the first embodiment; the multiplexing mirror  52  is disposed on the optical path between the second fly-eye lens  21 B and the polarization conversion element  23 . 
     According to the projector  1 E of the third embodiment, it is possible to reduce a distribution (light flux diameter) of the HDR light L H2  on the multiplexing mirror  52  as compared with the case where the multiplexing mirror  52  is disposed immediately after the first fly-eye lens  21 A, thus making it easier to prevent a decrease in the efficiency of the SDR light L S . 
     Other configurations, operations, and effects may be substantially similar to those of the illumination device and the projector  1  according to the foregoing first embodiment or the illumination device and the projector  1 B according to the foregoing second embodiment. 
     4. FOURTH EMBODIMENT 
     Next, description is given of an illumination device and a projector according to a fourth embodiment of the present disclosure. It is to be noted that, in the following, substantially the same components as those of the illumination device and the projector according to any of the foregoing first to third embodiments are denoted by the same reference numerals, and description thereof is omitted where appropriate. 
       FIG.  18    schematically illustrates a configuration example of a projector  1 F according to the fourth embodiment. 
     The projector  1 F according to the fourth embodiment includes a multiplexing optical system  50 F instead of the multiplexing optical system  50  in the projector  1  according to the first embodiment. 
     The multiplexing optical system  50 F multiplexes the SDR light L S  having entered the first fly-eye lens  21 A in the integrator optical system  20  and the HDR light L H2  having been modulated by the first spatial light modulator  13 , in an optical path between the second fly-eye lens  21 B and the second spatial light modulator  16 . More specifically, the multiplexing optical system  50 F multiplexes the SDR light L S  having entered the first fly-eye lens  21 A and the HDR light L H2  having been modulated by the first spatial light modulator  13 , in an optical path between the polarization conversion element  23  in the integrator optical system  20  and the second spatial light modulator  16 . 
     The multiplexing optical system  50 F includes a pair of multiplexing fly-eye lenses (multiplexing fly-eye lenses  51 A and  51 B) corresponding to the pair of fly-eye lenses (first fly-eye lens  21 A and second fly-eye lens  21 B) in the integrator optical system  20 , instead of the multiplexing lens  51  of the multiplexing optical system  50  in the first embodiment. The multiplexing fly-eye lenses  51 A and  51 B cause the HDR light L H2  having been modulated by the first spatial light modulator  13  to enter the optical path between the polarization conversion element  23  in the integrator optical system  20  and the second spatial light modulator  16 . 
     In addition, the multiplexing optical system  50 F includes the multiplexing mirror  52  having a structure similar to that of the multiplexing optical system  50  in the first embodiment. However, in the multiplexing optical system  50 F, the position where the multiplexing mirror  52  is disposed is different from that of the first embodiment; the multiplexing mirror  52  is disposed on the optical path between the polarization conversion element  23  and the second spatial light modulator  16 . 
     According to the projector  1 F of the fourth embodiment, it is possible to reduce a distribution (light flux diameter) of the HDR light L H2  on the multiplexing mirror  52  as compared with the case where the multiplexing mirror  52  is disposed immediately after the first fly-eye lens  21 A, thus making it easier to prevent a decrease in the efficiency of the SDR light L S . 
     Other configurations, operations, and effects may be substantially similar to those of the illumination device and the projector  1  according to the foregoing first embodiment or the illumination device and the projector  1 B according to the foregoing second embodiment. 
     5. FIFTH EMBODIMENT 
     Next, description is given of an illumination device and a projector according to a fifth embodiment of the present disclosure. It is to be noted that, in the following, substantially the same components as those of the illumination device and the projector according to any of the foregoing first to fourth embodiments are denoted by the same reference numerals, and description thereof is omitted where appropriate. 
     In each of the first to fourth embodiments, the configuration example is referred to, in which the first light (HDR light L H2 ) having been modulated by the first spatial light modulator  13  is reflected, and the second light (SDR light L S ) having entered the first fly-eye lens  21 A is transmitted, in the multiplexing mirror of the multiplexing optical system. However, a configuration may also be adopted, in which a relationship between the reflection and the transmission in the multiplexing mirror is reversed between the first light and the second light. 
       FIG.  19    schematically illustrates a configuration example of a projector  1 G according to the fifth embodiment. 
     The projector  1 G according to the fifth embodiment adopts an optical path arrangement with a positional relationship in which the optical path of the HDR light L H1  and the optical path of the SDR light L S  are interchanged. In addition, the projector  1 G according to the fifth embodiment includes a multiplexing optical system  50 G instead of the multiplexing optical system  50  in the projector  1  according to the first embodiment. 
     The multiplexing optical system  50 G includes the multiplexing fly-eye lens  51 A and a multiplexing mirror  52 G. The multiplexing mirror  52 G includes at least one transmission part  70  that transmits the HDR light L H2  having been modulated by the first spatial light modulator  13 . The multiplexing mirror  52 G has a structure in which, for example, a region other than at least the transmission part  70  functions as a reflective element to the SDR light L S , and a region of the transmission part  70  has a function of transmitting the HDR light L H2 . In the multiplexing mirror  52 G, the region other than the transmission part  70  may be a reflective mirror or a dichroic mirror that reflects the SDR light L S . 
     Other configurations, operations, and effects may be substantially similar to those of the illumination device and the projector according to any of the foregoing first to fourth embodiments. 
     First Modification Example of Fifth Embodiment 
       FIG.  20    schematically illustrates a configuration example of a main part of a projector  1 H according to a first modification example of the fifth embodiment.  FIG.  21    schematically illustrates a configuration example of a multiplexing mirror in the projector  1 H according to the first modification example of the fifth embodiment. 
     The projector  1 H according to the first modification example includes a multiplexing optical system  50 H instead of the multiplexing optical system  50 G in the projector  1 G according to the fifth embodiment. 
     The multiplexing optical system  50 H in the first modification example includes the multiplexing fly-eye lens  51 A and a multiplexing mirror  52 H. 
     In the multiplexing optical system  50 H, the multiplexing fly-eye lens  51 A generates the HDR light beams L H21 , L H22 , and L H23 , i.e., a plurality of light fluxes divided from the incident HDR light L H2 . It is to be noted that  FIG.  20    exemplifies an example in which the multiplexing fly-eye lens  51 A includes three lens elements and the light flux of the HDR light L H2  is divided into three; however, the number of lens elements of the multiplexing fly-eye lens  51 A and the number of divisions of the light fluxes may be each two. In addition, the number of the lens elements of the multiplexing fly-eye lens  51 A and the number of divisions of the light fluxes may be each four or more. 
     The multiplexing mirror  52 H has a plurality of transmission parts  71 ,  72 , and  73  according to the number of divisions of the light fluxes divided by the multiplexing fly-eye lens  51 A. The multiplexing mirror  52 H is disposed to allow the plurality of transmission parts  71 ,  72 , and  73  to be positioned on respective optical paths of the plurality of HDR light beams L H21 , L H22 , and L H23  generated by the multiplexing fly-eye lens  51 A. The plurality of transmission parts  71 ,  72 , and  73  transmit, respectively, the plurality of HDR light beams L H21 , L H22 , and L H23  generated by the multiplexing fly-eye lens  51 A toward a plurality of lens elements of the second fly-eye lens  21 B. The structure and transmission characteristics of each of the plurality of transmission parts  71 ,  72 , and  73  are substantially similar to those of the transmission part  70  in the multiplexing optical system  50 G. It is to be noted that the plurality of HDR light beams L H21 , L H22 , and L H23  generated by the multiplexing fly-eye lens  51 A are incident on the multiplexing mirror  52 H at different positions in the Z-direction with respect to the optical axis Z 1  of the integrator optical system  20 . For this reason, the light flux diameters of the plurality of HDR light beams L H21 , L H22 , and L H23  that are incident on the multiplexing mirror  52 H are of different respective sizes depending on positions of incidence. The sizes of the plurality of transmission parts  71 ,  72 , and  73  are sizes corresponding to the light flux diameters of the plurality of HDR light beams L H21 , L H22 , and L H23  that are incident on the multiplexing mirror  52 H, and thus are sizes different from each other. 
     Other configurations, operations, and effects may be substantially similar to those of the illumination device and the projector  1 G according to the foregoing fifth embodiment. 
     Second Modification Example of Fifth Embodiment 
       FIG.  22    is a plan view schematically illustrating a configuration example of a multiplexing mirror  52 I in a projector according to a second modification example of the fifth embodiment. 
     Similarly to the projector  1 B according to the second embodiment, the projector according to the second modification example has a configuration corresponding to color display. 
     A multiplexing optical system in the projector according to the second modification example includes the multiplexing fly-eye lens  51 A and the multiplexing mirror  52 I. 
     Similarly to the projector  1 B according to the second embodiment, the HDR light L H2  including the plurality of color light beams (red HDR light L HR , green HDR light L HG , and blue HDR light L HB ) enters the multiplexing optical system in the projector according to the second modification example. The mutually different color light beams (red HDR light L HR , green HDR light L HG , and blue HDR light L HB ) enter a plurality of lens elements of the multiplexing fly-eye lens  51 A. 
     The multiplexing mirror  52 I includes a plurality of transmission parts (a red transmission part  71 R, a green transmission  72 G, and a blue transmission part  73 B) that transmit respective color light beams having been modulated by the first spatial light modulator  13  at spatially different positions for respective colors. The multiplexing mirror  52 I is disposed to allow the red transmission part  71 R, the green transmission  72 G, and the blue transmission part  73 B to be positioned on respective optical paths of the red HDR light L HR , the green HDR light L HG  and the blue HDR light L HB  from the multiplexing fly-eye lens  51 A. The red transmission part  71 R, the green transmission  72 G, and the blue transmission part  73 B transmit, respectively, the red HDR light L HR , the green HDR light L HG , and the blue HDR light L HB  from the multiplexing fly-eye lens  51 A toward a plurality of lens elements of the second fly-eye lens  21 B. In the multiplexing mirror  52 I, a region other than the red transmission part  71 R, the green transmission  72 G, and the blue transmission part  73 B may be a reflective mirror or a dichroic mirror that reflects the SDR light L S . 
     It is to be noted that the red HDR light L HR , the green HDR light L HG , and the blue HDR light L HB  from the multiplexing fly-eye lens  51 A are incident on the multiplexing mirror  52 I at spatially different positions in the Z-direction with respect to the optical axis Z 1  of the integrator optical system  20 . For this reason, the light flux diameters of respective color light beams incident on the multiplexing mirror  52 I are of different respective sizes depending on positions of incidence. The sizes of the red transmission part  71 R, the green transmission  72 G, and the blue transmission part  73 B are sizes corresponding to the light flux diameters of the respective color light beams incident on the multiplexing mirror  52 I, and thus are sizes different from each other. 
     Other configurations, operations, and effects may be substantially similar to those of the illumination device and the projector  1 B according to the foregoing second embodiment or the illumination device and the projector  1 H according to the first modification example of the fifth embodiment. 
     6. OTHER EMBODIMENTS 
     The technique according to the present disclosure is not limited to the descriptions of the foregoing embodiments, and may be modified in a wide variety of ways. 
     For example, the description has been given, in each of the foregoing embodiments, by exemplifying the case where the illumination device is applied to the projector and where the illumination target by the illumination device is the second spatial light modulator  16  that generates a projection image. However, the illumination device may be applied to an apparatus other than the projector. 
     For example, the present technology may have the following configurations. 
     According to the present technology having the following configurations, the first light having been modulated by the first spatial light modulator and the second light having entered the first fly-eye lens of the integrator optical system are multiplexed in the optical path between the first fly-eye lens and the illumination target, thus making it possible to achieve a high dynamic range and to suppress a decrease in the light utilization efficiency. 
     (1) 
     An illumination device including: 
     a first light source unit that emits first light of a first wavelength band; 
     a first spatial light modulator where the first light from the first light source unit enters; 
     a second light source unit that emits second light of a second wavelength band; 
     an integrator optical system including a first fly-eye lens where the second light from the second light source unit enters, the integrator optical system generating illumination light for an illumination target on a basis of the first light having been modulated by the first spatial light modulator and on a basis of the second light from the second light source unit; and 
     a multiplexing optical system that multiplexes the second light having entered the first fly-eye lens and the first light having been modulated by the first spatial light modulator, in an optical path between the first fly-eye lens and the illumination target. 
     (2) 
     The illumination device according to (1), in which the second wavelength band includes the first wavelength band, and is a band wider than the first wavelength band. 
     (3) 
     The illumination device according to (1) or (2), in which the illumination target includes a second spatial light modulator that modulates the illumination light to generate a projection image. 
     (4) 
     The illumination device according to any one of (1) to (3), in which 
     the multiplexing optical system includes at least one multiplexing mirror disposed in the optical path between the first fly-eye lens and the illumination target, and 
     the multiplexing mirror includes at least one reflection part that reflects the first light having been modulated by the first spatial light modulator or at least one transmission part that transmits the first light having been modulated by the first spatial light modulator. 
     (5) 
     The illumination device according to (4), in which the multiplexing optical system further includes a multiplexing lens that causes the first light having been modulated by the first spatial light modulator to enter the optical path between the first fly-eye lens in the integrator optical system and the illumination target. 
     (6) 
     The illumination device according to (4) or (5), in which 
     the second wavelength band includes the first wavelength band, and is a band wider than the first wavelength band, and 
     the reflection part in the multiplexing mirror has a reflective function for the first wavelength band and has a transmissive function for a band other than the first wavelength band in the second wavelength band. 
     (7) 
     The illumination device according to any one of (1) to (6), in which 
     the integrator optical system further includes a second fly-eye lens paired with the first fly-eye lens, and 
     the multiplexing optical system multiplexes the second light having entered the first fly-eye lens and the first light having been modulated by the first spatial light modulator, in an optical path between the first fly-eye lens and the second fly-eye lens. 
     (8) 
     The illumination device according to any one of (1) to (6), in which 
     the integrator optical system further includes a second fly-eye lens paired with the first fly-eye lens, 
     the second fly-eye lens is disposed between the first fly-eye lens and the illumination target, and 
     the multiplexing optical system multiplexes the second light having entered the first fly-eye lens and the first light having been modulated by the first spatial light modulator, in an optical path between the second fly-eye lens and the illumination target. 
     (9) 
     The illumination device according to (8), in which the integrator optical system further includes a polarization conversion element disposed between the second fly-eye lens and the illumination target. 
     (10) 
     The illumination device according to (9), in which the multiplexing optical system includes a pair of multiplexing fly-eye lenses that cause the first light having been modulated by the first spatial light modulator to enter the optical path between the second fly-eye lens in the integrator optical system and the illumination target. 
     (11) 
     The illumination device according to (9) or (10), in which the multiplexing optical system multiplexes the second light having entered the first fly-eye lens and the first light having been modulated by the first spatial light modulator, in an optical path between the second fly-eye lens and the polarization conversion element. 
     (12) 
     The illumination device according to (9) or (10), in which the multiplexing optical system multiplexes the second light having entered the first fly-eye lens and the first light having been modulated by the first spatial light modulator, in an optical path between the polarization conversion element and the illumination target. 
     (13) 
     The illumination device according to any one of (1) to (7), in which 
     the first light includes a plurality of color light beams, and 
     the multiplexing optical system multiplexes the respective color light beams having been modulated by the first spatial light modulator with the second light having entered the first fly-eye lens at mutually different positions in the optical path between the first fly-eye lens and the illumination target. 
     (14) 
     The illumination device according to (13), in which 
     the multiplexing optical system includes the multiplexing mirror disposed in the optical path between the first fly-eye lens and the illumination target, and 
     the multiplexing mirror includes a plurality of reflection parts that reflect the respective color light beams having been modulated by the first spatial light modulator, or a plurality of transmission parts that transmit the respective color light beams having been modulated by the first spatial light modulator. 
     (15) 
     The illumination device according to (13), in which the multiplexing optical system includes a plurality of multiplexing mirrors disposed in the optical path between the first fly-eye lens and the illumination target, the plurality of multiplexing mirrors reflecting the respective color light beams. 
     (16) 
     A projector including: 
     an illumination device including a first spatial light modulator where first light of a first wavelength band enters; and 
     a second spatial light modulator that modulates illumination light from the illumination device to generate a projection image on a basis of an image signal, 
     the illumination device further including
         a first light source unit that emits the first light of the first wavelength band,   a second light source unit that emits second light of a second wavelength band,   an integrator optical system including a first fly-eye lens where the second light from the second light source unit enters, the integrator optical system generating illumination light for the second spatial light modulator on a basis of the first light having been modulated by the first spatial light modulator and on a basis of the second light from the second light source unit, and   a multiplexing optical system that multiplexes the second light having entered the first fly-eye lens and the first light having been modulated by the first spatial light modulator, in an optical path between the first fly-eye lens and the illumination target.
 
(17)
       

     The projector according to (16), further including a projection optical system that projects the projection image generated by the second spatial light modulator onto a projection plane. 
     (18) 
     The projector according to (16) or (17), in which the first spatial light modulator modulates the first light from the first light source unit on a basis of a signal of a high luminance region included in the image signal. 
     This application claims the benefit of Japanese Priority Patent Application JP2018-138366 filed with the Japan Patent Office on Jul. 24, 2018, the entire contents of which are incorporated herein by reference. 
     It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.