Patent Publication Number: US-2022239873-A1

Title: Image display apparatus

Description:
TECHNICAL FIELD 
     The present disclosure relates to an image display apparatus that displays an image on a screen having a cylindrical shape, for example. 
     BACKGROUND 
     Recently, a technology has been developed for projecting images on screens or the like having various shapes. For example, PTL 1 discloses an image display apparatus that displays an image on a full-circumference screen or the like. In the image display apparatus of PTL1, an optical unit is disposed opposite to an output unit. The optical unit controls the incident angle of image light outputted from an output unit (output light (illumination light) outputted from a light source) with respect to an irradiation target object. Further, PTL 2, for example, discloses a projection-type image display apparatus using top-hat diffusion elements to improve the light utilization efficiency. 
     CITATION LIST 
     Patent Literature 
     
         
         [PTL 1] International Publication No. WO 2018/163945 
         [PTL 2] Japanese Unexamined Patent Application Publication No. 2017-142482 
       
    
     SUMMARY OF THE INVENTION 
     Meanwhile, an improvement in the image quality has been required in the image display apparatus described above. 
     It is desirable to provide an image display apparatus making it possible to improve the image quality. 
     An image display apparatus according to one embodiment of the present disclosure includes: an output unit including a light source and outputting projection light outputted from the light source along a predetermined axis; an irradiation target member to be irradiated with the projection light; a first optical member disposed opposite to the output unit along the predetermined axis and controlling an incident angle of the projection light to be incident on the irradiation target member; and a second optical member included in the output unit and adjusting the illumination range of the projection light to be incident on the first optical member such that the illumination range has an aspect ratio substantially the same as an aspect ratio of an outer shape of the first optical member. 
     The image display apparatus according to one embodiment of the present disclosure includes the second optical member in the output unit including the light source. The second optical member adjusts the illumination range of the projection light to be incident on the first optical member such that the illumination range has an aspect ratio substantially the same as an aspect ratio of an outer shape of the first optical member. This improves the utilization efficiency of the projection light. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates an exemplary schematic configuration of an output unit of an image display apparatus according to a first embodiment of the present disclosure in Part (A), and the illumination range of image light outputted from the output unit in Part (B). 
         FIG. 2  is a perspective view illustrating an exemplary external configuration of the image display apparatus including the output unit illustrated in  FIG. 1 . 
         FIG. 3  is a schematic cross-sectional view of the image display apparatus illustrated in  FIG. 2 . 
         FIG. 4  is a diagram illustrating a specific example of an illumination range control unit illustrated in  FIG. 1 . 
         FIG. 5  is a diagram illustrating the illumination range of image light passing through the illumination range control unit illustrated in  FIG. 4 . 
         FIG. 6  is a diagram illustrating a specific example of the illumination range control unit illustrated in  FIG. 1 . 
         FIG. 7  is a diagram illustrating the illumination range of image light passing through the illumination range control unit illustrated in  FIG. 6 . 
         FIG. 8  illustrates a schematic configuration of an output unit of a typical image display apparatus of a comparative example in Part (A), and the illumination range of image light outputted from the output unit in Part (B). 
         FIG. 9  illustrates an exemplary schematic configuration of an output unit of an image display apparatus according to a modification example of the present disclosure in Part (A), and the illumination range of image light outputted from the output unit in Part (B). 
         FIG. 10  illustrates an exemplary schematic configuration of an output unit of an image display apparatus according to a second embodiment of the present disclosure in Part (A), and the illumination range of image light outputted from the output unit in Part (B). 
         FIG. 11  is a diagram illustrating an exemplary configuration of an optical system of the output unit. 
         FIG. 12  is a schematic diagram illustrating the relationship between each lens cell of a fly-eye lens and the illumination range. 
         FIG. 13  is a schematic cross-sectional view illustrating an exemplary configuration of each lens cell of the fly-eye lens used as an illumination control unit illustrated in  FIG. 10 . 
         FIG. 14A  illustrates the illumination light intensity distribution of image light Li passing through the lens cell (a lens cell  52   a ) of the fly-eye lens illustrated in  FIG. 13 . 
         FIG. 14B  illustrates the illumination light intensity distribution of image light Li passing through the lens cell (the lens cell  52   a ) of the fly-eye lens illustrated in  FIG. 13 . 
         FIG. 14C  illustrates the illumination light intensity distribution of image light Li passing through the lens cell (the lens cell  52   a ) of the fly-eye lens illustrated in  FIG. 13 . 
         FIG. 14D  illustrates the illumination light intensity distribution of image light Li passing through the lens cell (the lens cell  52   a ) of the fly-eye lens illustrated in  FIG. 13 . 
         FIG. 15  illustrates the sum of the illumination light intensity distributions with respect to the optical modulators illustrated in  FIGS. 14A to 14D . 
         FIG. 16  is a schematic cross-sectional view illustrating another exemplary configuration of each lens cell of a fly-eye lens used as the illumination range control unit illustrated in  FIG. 10 . 
         FIG. 17  is a schematic cross-sectional view illustrating another exemplary configuration of each lens cell of the fly-eye lens used as the illumination range control unit illustrated in  FIG. 10 . 
         FIG. 18  is a schematic cross-sectional view illustrating another exemplary configuration of each lens cell of the fly-eye lens used as the illumination range control unit illustrated in  FIG. 10 . 
         FIG. 19A  is a diagram illustrating an exemplary arrangement of the respective lens cells of the fly-eye lens illustrated in, for example,  FIG. 13 . 
         FIG. 19B  is a diagram illustrating an exemplary arrangement of the respective lens cells of the fly-eye lens illustrated in, for example,  FIG. 13 . 
         FIG. 19C  is a diagram illustrating an exemplary arrangement of the respective lens cells of the fly-eye lens illustrated in, for example,  FIG. 13 . 
         FIG. 20  illustrates the illumination light intensity distribution of image light on an optical modulator in a typical image display apparatus. 
         FIG. 21  is a diagram illustrating the relationship between the position of a screen and the luminance observed when the screen is irradiated with image light having the illumination distribution illustrated in  FIG. 20 . 
         FIG. 22  is a diagram illustrating the relationship between the position of the screen and the luminance observed when the screen is irradiated with image light having the illumination distribution illustrated in  FIG. 15 . 
         FIG. 23  is a schematic diagram illustrating an exemplary configuration of the optical system in the image display apparatus illustrated in, for example,  FIG. 1 . 
         FIG. 24  is a schematic diagram illustrating another exemplary configuration of the optical system in the image display apparatus illustrated in, for example,  FIG. 1 . 
         FIG. 25  is a schematic diagram illustrating another exemplary configuration of the optical system in the image display apparatus illustrated in, for example,  FIG. 1 . 
         FIG. 26  is a schematic diagram illustrating another exemplary configuration of the optical system in the image display apparatus illustrated in, for example,  FIG. 1 . 
         FIG. 27  is a block diagram illustrating another exemplary configuration of the image display apparatus illustrated in, for example,  FIG. 1 . 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     Hereinafter, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following embodiments. Further, the present disclosure is not limited to the arrangement, the dimensions, the dimension ratio, and the like of each component illustrated in the respective drawings. Note that the order of the description is as follows. 
     1. First Embodiment (Example of Image Display Apparatus Including Illumination Range Control Unit in Output unit) 
     1-1. Configuration of Image Display Apparatus 
     1-2. Operation of Image Display Apparatus 
     1-3. Workings and Effects 
     2. Modification Example (Example Using Rod Integrator Lens as Illumination Range Control Unit) 
     3. Second Embodiment (Example of Image Display Apparatus Including Illumination Range Control Unit Having Function of Controlling Intensity Distribution in Emission Unit) 
     3-1. Configuration of Image Display Apparatus 
     3-2. Workings and Effects 
     4. Example of Optical System of Image Display Apparatus 
     1. First Embodiment 
     Part (A) of  FIG. 1  illustrates an exemplary schematic configuration of a main part (an output unit  10 ) of an image display apparatus according to a first embodiment of the present disclosure (an image display apparatus  1 ). Part (B) of  FIG. 1  illustrates the illumination range S of image light Li outputted from the output unit  10  to a reflection mirror  15 .  FIG. 2  is a perspective view illustrating an external configuration of the image display apparatus  1 .  FIG. 3  schematically illustrates a cross-sectional configuration of the image display apparatus  1  taken along the line I-I in  FIG. 2 . The image display apparatus  1  is capable of displaying an image on a full-circumference screen having a rotation body shape, for example. 
     (1-1. Configuration of Image Display Apparatus) 
     The image display apparatus  1  of the present embodiment includes the output unit  10  including a light source  11 , an illumination range control unit  12 , an optical modulator  13 , and a projector lens  14 . The image display apparatus  1  also has a cylindrical shape and includes a pedestal  31 , a screen  20 , and a top plate  32 . The output unit  10  is disposed on the pedestal  31 . The reflection mirror  15  reflecting the image light Li outputted from the output unit  10  toward the screen is installed on the top plate  32 . The output unit  10  emits the image light Li along a predetermined axis (e.g., an axis J 10 ). The output unit  10  and the reflection mirror  15  are arranged opposite to each other about the axis J 10 . The screen  20  is disposed over the entire circumference around the axis J 10 , for example. 
     In the output unit  10  of the present embodiment, the illumination range control unit  12 , the optical modulator  13 , and the projector lens  14  are arranged in this order on the optical path of the output light outputted from the light source  11  (hereinafter, referred to as image light Li for convenience), for example. The illumination range control unit  12  adjusts the illumination rage of the image light Li outputted from the light source  11  such that the illumination range has an aspect ratio substantially the same as the aspect ratio of the outer shape of the reflection mirror  15 . The reflection mirror  15  corresponds to a specific example of a “first optical member” of the present disclosure, and the illumination range control unit  12  corresponds to a specific example of a “second optical member” of the present disclosure. 
     The output unit  10  includes the light source  11 , the illumination range control unit  12 , the optical modulator  13 , and the projector lens  14 , as described above, and outputs the image light Li radially toward the reflection mirror  15 . Note that the image light Li constitutes an image including a moving image and a still image. The image light Li corresponds to “projection light” of the present disclosure. The output unit  10  is installed upward at a position substantially at the center of the pedestal  31 , for example. Thus, the image light Li is outputted radially along a predetermined axis (the axis J 10 ) extending in a Y-axis direction. 
     The output unit  10  is configured by, for example, a laser scanning color projector or the like that scans laser beams corresponding to respective colors RGB and displays respective pixels. Alternatively, the output unit  10  may be configured by any projector capable of projecting the image light Li. For example, a small mobile projector (pico-projector), a projector using a monochromatic laser beam, or the like may be appropriately used as the output unit  10  depending on the size and application of the image display apparatus  1 . Note that an exemplary configuration of the optical system of the output unit  10  will be described later with reference to  FIGS. 23 to 27 . 
     The light source  11  may be, for example, a solid-state light source, such as a semiconductor laser (LD) or a light emitting diode (LED), a halogen lamp, a metal halide lamp, a xenon lamp, or the like. 
     The illumination range control unit  12  adjusts the illumination range S of the image light Li to be incident on the reflection mirror  15  such that the illumination range has an aspect ratio substantially the same as the aspect ratio of the outer shape of the reflection mirror  15 , as described above. It is sufficient that the illumination range control unit  12  has a shape having substantially the same aspect ratio as the aspect ratio of the reflection mirror  15 . For example, in a case where the reflection mirror  15  has an aspect ratio of 1:1, it is preferable to use a fly-eye lens  12 A including a square lens cell of x 1 :x 2 =1:1 illustrated in  FIG. 4  as the illumination range control unit  12 . Accordingly, the image light Li projected from the output unit  10  to the reflection mirror  15  has a substantially square shape having substantially the same aspect ratio as that of the outer shape of the reflection mirror  15 . That is, as illustrated in  FIG. 5 , the peripheral portion of the illumination range S of the image light Li incident on the reflection mirror  15  is brought into close contact with four points (A 1 , A 2 , A 3 , and A 4 ) on the circumference of the reflection mirror by adjusting the projection distance using, for example, the projector lens  14  or the like. This improves the illumination efficiency of the image light Li outputted from the light source  11  to the reflection mirror  15 . 
     Note that it is sufficient that the outer shape of the lens cell of the fly-eye lens used as the illumination range control unit  12  has an aspect ratio substantially the same as the aspect ratio of the reflection mirror  15 . Further, any number of vertical arrays and horizontal arrays of the lens cells may be arranged in the fly-eye lens. Generally, the more arrays are arranged, the more the uniformity of the illumination light is improved. Thus, although the fly-eye lens  12 A having 3×4 arrays including twelve lens cells  12   a  is illustrated in  FIG. 4 , the number of lens cell arrays is not limited thereto. For example, a fly-eye lens having 5×6 arrays including, for example, thirty lens cells may be used as the illumination range control unit  12 . Alternatively, a fly-eye lens having vertical and horizontal arrays in the same number, for example, 4×4 arrays including sixteen lens cells may be used as the illumination range control unit  12 . 
     Further, although the fly-eye lens  12 A including the lens cells  12   a  each having a square shape is illustrated in  FIG. 4 , the outer shapes of the lens cells of the fly-eye lens are not limited thereto. For example, as illustrated in  FIG. 6 , a fly-eye lens  12 B including lens cells  12   b  each having a substantially regular hexagonal outer shape may be used as the illumination range control unit  12 . In a case where the fly-eye lens  12 B is used, the illumination range S has a substantially regular hexagonal shape, and the peripheral portion of the illumination range S of the image light Li incident on the reflection mirror  15  is in close contact with six points (B 1 , B 2 , B 3 , B 4 , B 5 , and B 6 ) on the circumference of the reflection mirror  15 , as illustrated in, for example,  FIG. 7 . 
     Note that the shape of each lens cell (e.g., the lens cell  12   a ) of the fly-eye lens used as the illumination range control unit  12  is not limited to a substantially rectangular shape or a substantially hexagonal shape. Each lens cell may have a pentagonal, heptagonal, or higher polygonal shape. 
     The optical modulator  13  performs spatial modulation of the image light Li (or RGB color light components of the image light Li). For example, the optical modulator  13  may be a reflective liquid crystal panel called a transmissive liquid crystal panel or a liquid crystal on silicon (LCOS). Note that, in place of the optical modulator  13 , a digital micromirror device (DMD) or a micro electromechanical system (MEMS) mirror may be used as the first optical member. 
     The projector lens  14  enlarges and projects the image light Li to the reflection mirror  15 . 
     The reflection mirror  15  has a reflection surface (a surface  15 S) that reflects the image light Li outputted from the output unit  10 . The reflection mirror  15  controls the incident angle of the image light Li outputted from the output unit  10  to the screen  20 . Specifically, the reflection mirror  15  controls the incident angle of the image light Li with respect to the screen  20  to be substantially constant. Note that the substantially constant incident angle includes an incident angle within an angle range (allowable angle range) in which image displaying is properly performed. The allowable angle range is determined depending on the diffraction property of a transmissive diffuser HOE used as the irradiation target member  22 , for example. Thus, the image light Li radially outputted from the output unit  10  is outputted in the form of substantially parallel light toward the screen  20 . 
     The reflection mirror  15  has the reflection surface (the surface  15 S) having a rotationally symmetrical shape about the axis J 10 . The reflection mirror  15  is disposed opposite to the output unit  10  with respect to the axis J 10  such that the reflection surface (the surface  15 S) faces the output unit  10 . For instance, the reflection surface (the surface  15 S) of the reflection mirror  15  is a rotation surface formed by rotating a curved line partially cut from a parabola about the axis J 10 . The rotation surface is formed such that an concave side of the parabola (a focal side of the parabola) serves as a light reflection side (the reflection surface (the surface  15 S)) and that the axis of the parabola differs from the axis J 10 , for example. Further, the reflection surface (the surface  15 S) has a shape having a vertex on the axis J 10 . That is, the reflection surface (the surface  15 S) has a convex shape at the intersection between the rotation surface and the axis J 10  when viewed from the output unit  10 . Further, the cross-sectional shapes of the left and right portions of the reflection mirror  15  across the axis J 10  are concave parabolic shapes when viewed from the output unit  10 . 
     Examples of the material of the reflection mirror  15  include resin such as acrylic, glass, and metal. The reflection mirror  15  is formed by, for example, conducting mirror finishing on a surface of the material described above such that the surface roughness Ra is less than about 0.1 μm. Further, the reflection surface (the surface  15 S) of the reflection mirror  15  may be subjected to high-reflectance coating using aluminum (A 1 ), silver (Ag), or the like. This makes it possible to reflect the image light Li incident on the reflection surface (the surface  15 S) with high efficiency. Further, the front face of the reflection surface (the surface  15 S) may be subjected to protective coating using a silicon oxide (SiO 2 ) film, a polymerized film, or the like. 
     Note that the material of the reflection mirror  15  is not limited to the above-described materials, and any material may be used depending on machining accuracy, productivity, and the like. Further, the materials used in the high reflectance coating and the protective coating is not limited to particular materials. 
     The screen  20  has a cylindrical shape and is disposed over, for example, the entire circumference around the axis J 10 , as described above. The screen  20  includes, for example, a support member  21  and the irradiation target member  22 . Further, the screen  20  having a cylindrical shape is disposed such that its central axis is substantially aligned with the axis J 10  of the output unit  10 . Note that the screen  20  exemplified in  FIGS. 2 and 3  has the same diameter as the pedestal  31 ; however, this is non-limiting. The diameter and the height of the screen  20  may be determined as appropriate. 
     The support member  21  supports the irradiation target member  22 . The support member  21  may be configured by, for example, an optical transparent base. Examples of the base include a plastic material, such as an acrylic resin or a polycarbonate resin, glass, or the like. 
     The irradiation target member  22  diffuses the image light Li reflected from the reflection mirror  15  toward the outside of the image display apparatus  1 . The irradiation target member  22  is configured by, for example, a diffractive optical element, specifically, a holographic optical element (HOE). The HOE is an optical elements that diffracts only light having a particular wavelength and transmit remaining light in a selective manner based on the incident angle. The irradiation target member  22  is configured by, for example, a transmissive diffuser HOE. Thus, the image light Li reflected from the reflection mirror  15  and incident on the transmissive diffuser HOE (the irradiation target member  22 ) from the inside of the image display apparatus  1  is diffused (scattered) in various directions and outputted to the outside of the image display apparatus  1 .  FIG. 3  schematically illustrates the state of the image light Li being incident on the transmissive diffuser HOE (the irradiation target member  22 ), being diffused (scattered), and being outputted to the outside. 
     The HOE exhibits the maximum diffraction efficiency when light having the same wavelength as the wavelength of reference light for exposure in the manufacture process is used as reproduction illumination light at an incident angle substantially the same as that of the reference light. That is, in the fabrication process of the transmissive diffuser HOE, for example, green light having a wavelength of about 530 nm is emitted as object light or reference light to a first surface of a photopolymer at an incident angle of about 40°. Reproduction light outputted vertically from a second surface of the transmissive diffuser HOE obtained thereby has a maximum intensity (luminance) when reproduction illumination light is incident on the first surface at an incident angle of 40°. Additionally, light having a wavelength different from that of the reference light used for the exposure (e.g., red light having a wavelength of 630 nm and blue light having a wavelength of 455 nm) has the maximum diffraction efficiency when the incident angle of the reference light is 40°. 
     As described above, the image light Li is incident on at a constant incident angle depending on the incident angle of the reference light used for the exposure of the transmissive diffuser HOE. This makes it possible to increase the luminance of the image display apparatus  1 . Note that the incident angles of the object light and the reference light for the exposure of the transmissive diffuser HOE are not limited to the above-described examples, and may be appropriately determined depending on the application of the image display apparatus  1  or the properties of the transmissive diffuser HOE. The incident angle of the image light Li with respect to the irradiation target member  22  is preferably 40° or greater and 75° or less, for example. This makes it possible to secure the size of an image to be projected to the screen. 
     The HOE used as the irradiation target member  22  may be a volume type HOE that records an interference fringe by exposing a photosensitive material, or a surface-relief HOE that produces an interference fringe using an uneven shape of the material surface. Alternatively, in place of the transmissive diffuser HOE, a reflective HOE may be used as the irradiation target member  22 . 
     Note that the screen  20  is not limited to the configuration described above. For example, the support member  21  may also serve as the irradiation target member  22 . Further, the screen  20  may include, for example, an additional transmissive diffuser HOE or a combination of a reflective mirror HOE and a reflective diffuser HOE. In that case, it is preferable to arrange the HOE at a position after the irradiation target member  22  on the optical path of the image light Li. This reduces the amount of light leaking through the screen  20 , and improves the transparency and image quality (image contrast) of the screen  20 . 
     Alternatively, a Fresnel screen may be used as the screen  20 . This improves the luminance compared with the screen  20  configured by the HOE. Alternatively, a scattering particle screen may be used as the screen  20 . This reduces the cost compared with the screen  20  configured by the HOE, and allows the image display apparatus  1  to have a large size. 
     The pedestal  31  holds, for example, the output unit  10 , the screen  20 , and the top plate  32 . For instance, the pedestal  31  is disposed below the image display apparatus  1 . The output unit  10 , the screen  20 , and the top plate  32  are held by any non-illustrated holding mechanism. For example, a partition plate  33  is disposed between the pedestal  31  and the screen  20 . Further, although not illustrated, a power supply source such as a battery, a speaker, devices used to operate the image display apparatus  1 , and the like are arranged on the pedestal  31  in an appropriate manner. The shape or the like of the pedestal  31  is not limited. For example, although  FIG. 1  illustrates the pedestal  31  having a cylindrical shape, any shape such as a rectangular parallelepiped shape may be selected. 
     The top plate  32  holds the reflection mirror  15 . For example, the top plate  32  is disposed above the image display apparatus  1 . 
     The partition plate  33  partitions the interior space of the pedestal  31  in which the output unit  10  is disposed and the interior space of the screen  20 , for example. The partition plate  33  is provided with an opening  33 H at a position facing the output unit  10  so as not to hinder emission of the image light Li from the output unit  10  to the reflection mirror  30 . It is preferable that partition plate  33  include a material having a reflectance of, for example, 50% or less. This reduces the projection intensity of the image on the partition plate  33  when the image light Li is reflected from the inside of the screen  20 , for example. 
     (1-2. Operation of Image Display Apparatus) 
     In the image display apparatus  1 , the illumination range control unit  12 , the optical modulator  13 , and the projector lens  14  are arranged in this order on the optical path of the image light Li outputted from the light source  11 . The image light Li is adjusted by the illumination range control unit  12  such that the cross-sectional shape of the light beam of the image light Li has an aspect ratio substantially the same as, for example, the aspect ratio of the outer shape of the reflection mirror  15  before being outputted toward the optical modulator  13 . The image light Li outputted from the illumination range control unit  12  passes through the optical modulator  13  and the projector lens  14  in this order, and is outputted radially along the axis J 10  from the projector lens  14  toward the reflection mirror  15 . The image light Li is radially reflected from the reflection surface  15 S of the reflection mirror  15  toward the entire circumference of the screen  20 , and enters the screen  20  at a substantially constant incident angle. The image light Li incident on the screen  20  is diffracted by the irradiation target member  22  and diffused before being outputted to the outside of the image display apparatus  1 , whereby an image such as a full circumference image is displayed on the outside of the screen  20   
     (1-3. Workings and Effects) 
     The image display apparatus  1  includes the output unit  10 , the screen  20 , and the reflection mirror  15 . The output unit  10  outputs the image light Li along a predetermined axis (the axis J 10 ). The screen  20  is irradiated with the image light Li. The reflection mirror  15  is disposed opposite to the output unit  10  along the axis J 10 , and emits the image light Li to the screen  20  at a predetermined angle. In the present embodiment, the illumination range control unit  12  is disposed in the output unit  10  and adjusts the illumination range S of the image light Li outputted from the light source  11  to the reflection mirror  15  such that the illumination range S has an aspect ratio substantially the same as the aspect ratio of the outer shape of the reflection mirror  15 . This improves the illumination efficiency of the reflection mirror  15 . 
     Part (A) of  FIG. 8  illustrates an exemplary schematic configuration of a typical output unit (an output unit  1000 ) in an image display apparatus that displays an image on a full-circumference screen as described above, and Part (B) of  FIG. 8  illustrates an illumination range S 1000  (B) of image light Li 1000  outputted from the output unit  1000  to a reflection mirror  1500 . In the typical image display apparatus, a fly-eye lens  1200 , an optical modulator  1300  and a projector lens  1400  are arranged in this order on the optical path of the image light Li 1000  outputted from a light source  1100 . The image light Limo incident on the projector lens  1400  is radially outputted from the projector lens  1400  toward the reflection mirror  1500 . In such an image display apparatus, the fly-eye lens  1200  is used to uniformize the brightness of the image light Li 1000 . 
     For the image display apparatus that displays an image on a full-circumference screen, image light needs to be emitted to only the reflection mirror. Thus, the display area is controlled by a video signal. As illustrated in  FIG. 8 , such an image display apparatus generates a loss of brightness corresponding to illumination light incident on the optical modulator  1300  but not on the reflection mirror  1500 , i.e., the image light Li 1000  incident on the outside of the reflection mirror  1500 . As a result, the efficiency of illumination to the full circumference screen is deteriorated, resulting in deterioration of the image quality. 
     In contrast, the image display apparatus  1  of the present embodiment includes the illumination range control unit  12  arranged on the optical path of image light Li outputted from the light source  11 , and the illumination range S of the image light Li outputted from the light source  11  to the reflection mirror  15  is adjusted such that the illumination range S has an aspect ratio substantially the same as the aspect ratio of the outer shape of the reflection mirror  15 , whereby the image light Li is outputted toward the optical modulator  13 , for example. The illumination range control unit  12  includes, for example, a fly-eye lens (e.g., the fly-eye lens  12 A or  12 B) having an outer shape with the aspect ratio substantially the same as the aspect ratio of the outer shape of the reflection mirror  15 . This reduces the proportion of the image light Li outputted from the output unit  10  to the outside of the reflection mirror  15  in the illumination range S. This improves the illumination efficiency of the image light Li. 
     As described above, in the image display apparatus  1  of the present embodiment, the illumination range control unit  12  is arranged in the output unit  10 , and the illumination range S of the image light Li to be incident on the reflection mirror  15  is adjusted such that the illumination range S has an aspect ratio substantially the same as the aspect ratio of the outer shape of the reflection mirror  15  before being outputted to the optical modulator  13 . This improves the illumination efficiency of the image light Li and the image quality. 
     Described next is a second embodiment and a modification example of the present disclosure. Hereinafter, the same reference numerals are used for the same components as those in the above-described embodiments, and the description thereof is omitted as appropriate. 
     2. Modification Example 
     Part (A) of  FIG. 9  illustrates an exemplary schematic configuration of a main part (an output unit  40 ) of an image display apparatus according to a modification example of the present disclosure (an image display apparatus  2 ). Part (B) of  FIG. 9  illustrates the illumination range S of image light Li outputted from the output unit  40  to the reflection mirror  15 . The image display apparatus  2  is capable of displaying an image on a full-circumference screen having a rotation body shape, for example. The image display apparatus  2  according to the modification example is different from the image display apparatus according to the embodiment described above in that a rod integrator lens is used as the illumination range control unit  42 . 
     The illumination range control unit  42 , which adjusts the illumination range S of the image light Li to be incident on the reflection mirror  15  as described above, may be configured by a rod integrator lens having a cylindrical shape or a square or higher polygonal shape in place of the fly-eye lens  12 A or  12 B having substantially the same aspect ratio as the outer shape of the reflection mirror  15 . 
     As described above, in the image display apparatus  2  of this modification example, the rod integrator lens having a cylindrical or square or higher polygonal shape and the aspect ratio substantially the same as the aspect ratio of the outer shape of the reflection mirror  15  is used as the illumination range control unit  42 . Thus, the illumination range S of the image light Li incident on the reflection mirror  15  has an aspect ratio substantially the same as the aspect ratio of the reflection mirror  15 . This reduces the proportion of the image light Li emitted to the outside of the outer shape of the reflection mirror  15 . Accordingly, it is possible to obtain the same effects as those in the first embodiment described above. 
     In place of the rod integrator lens, a diffuser plate, a volume type HOE, a surface-relief HOE, or a MEMS mirror may be used as the illumination range control unit  42 . 
     3. Second Embodiment 
     Part (A) of  FIG. 10  illustrates an exemplary schematic configuration of a main part (an output unit  50 ) of an image display apparatus according to a second embodiment of the present disclosure (an image display apparatus  3 ). Part (B) of  FIG. 10  illustrates the illumination range S of image light Li outputted from the output unit  50  to the reflection mirror  15 . The image display apparatus  3  is capable of displaying an image on the full circumference screen having a rotation body shape, for example. 
     (3-1. Configuration of Image Display Apparatus) 
     In the image display apparatus  3  of the present embodiment, a fly-eye lens (e.g., a fly-eye lens  52 A,  52 B,  52 C, or  52 D) including a plurality of lenses different from each other in any one of the lens pitch (P), the radius of curvature (R), the on-axis thickness (t), and the refractive index (n) is used as an illumination range control unit  52 . Thus, the illumination range S with respect to the reflection mirror  15  has an intensity distribution. For example, in the image display apparatus  3  of the present embodiment, the image light Li having a larger intensity distribution in its central portion than in its peripheral portion is projected to the reflection mirror  15 . The present embodiment is different from the first embodiment described above in this regard. 
       FIG. 11  illustrates an exemplary optical system in a range from the illumination range control unit  52  (the fly-eye lens  114 ) to the optical modulator  13  (an LCOS  118 ) (see  FIG. 23  for details). The image light Li incident on the illumination range control unit  52  enters the optical modulator  13  through, for example, a main condensing lens  115 , a channel condensing lens  116 , and a polarizing beam splitter (PBS)  117 .  FIG. 12  illustrates the relationship between one of the plurality of lens cells of the fly-eye lens used as the illumination range control unit  52  and the illumination range S of the image light Li incident on the optical modulator  13 . 
     The relationship between the plurality of lens cells of the fly-eye lens and the illumination range (W) of the image light Li on the optical modulator  13  is represented by the following Expressions (1) to (3): 
         W=M×P   Expression (1)
 
         M=fc/f   Expression (2)
 
         f=nR   2 /( n− 1)[2 nR−t ( n− 1)]  Expression (3),
 
     where M denotes the magnification, P denotes the lens pitch of the fly-eye lens, f denotes the focal length of the fly-eye lens, fc denotes the focal length of the condensing lens, R denotes the radius of curvature of the fly-eye lens, n denotes the material refractive index of the fly-eye lens, and t denotes the on-axis thickness. 
     It is apparent from Expressions (1) to (3) that it is possible for the fly-eye lens to set any illumination range (W) on the optical modulator  13  by changing at least one of the lens pitch (P), the radius of curvature (R), the on-axis thickness (t), and the material refractive index (n). For instance, when the on-axis thickness of the fly-eye lens (t) is increased, the focal length (f) is elongated and the magnification (M) is lowered. As a result, the illumination region (W) is narrowed. When the radius of curvature (R) of the fly-eye lens is increased, the focal length (f) is elongated and the magnification (M) is lowered. As a result, the illumination range (W) is narrowed. When the refractive index (n) of the fly-eye lens is reduced, the focal length (f) is elongated and the magnification (M) is lowered. As a result, the illumination range (W) is narrowed. 
     In the present embodiment, the fly-eye lens (the fly-eye lens  52 A,  52 B,  52 C, or  52 D) including four lens cells different from each other in any one of the lens pitch (P), the radius of curvature (R), the on-axis thickness (t), and the material refractive index (n) of the fly-eye lens is used as the illumination range control unit  52 .  FIG. 13  illustrates exemplary cross-sectional views of the four lens cells of the fly-eye lens  52 A, namely, lens cells  51   a   1 ,  52   a   2 ,  52   a   3 , and  52   a   4 , and changes of the optical paths of light incident on the lens cells  51   a   1 ,  52   a   2 ,  52   a   3 , and  52   a   4  (dashed lines). These lens cells  51   a   1 ,  52   a   2 ,  52   a   3 , and  52   a   4  have respective lens pitches P 1 , P 2 , P 3 , and P 4 . These lens pitches have a magnitude relationship represented by P 1 &gt;P 2 &gt;P 3 &gt;P 4 . 
       FIGS. 14A to 14D  illustrate the illumination light intensity distributions (I 1  to I 4 ) of light passing through the respective lens cell  51   a   1 ,  52   a   2 ,  52   a   3 , and  52   a   4  on the optical modulator  13 . As illustrated in  FIGS. 14A to 14D , the lens pitch (P) has a proportional relationship with the illumination range (W) on the optical modulator  13 . For example, the illumination range (W) on the optical modulator  13  is narrowed by reducing the lens pitch (P).  FIG. 15  illustrates a correction distribution (objective; dashed line) and the sum of the illumination light intensity distributions (I 1  to I 4 ) illustrated in  FIG. 14A  to  FIG. 14D  (solid line). Accordingly, the lens cells  51   a   1 ,  52   a   2 ,  52   a   3 , and  52   a   4  having different lens pitches are appropriately arranged in the fly-eye lens such that the illumination ranges (W 1 , W 2 , W 3 , and W 4 ) overlap each other. This allows the illumination range S on the optical modulator  13  to have a desired intensity distribution. 
     Note that the illumination light intensity distributions I 1  to I 4  illustrated in  FIGS. 14A to 14D  may be obtained by adjusting the radius of curvature (R), the on-axis thickness (t), or the material refractive index (n).  FIG. 16  illustrates exemplary cross-sectional configurations of the four lens cells  51   b   1 ,  52   b   2 ,  52   b   3 , and  52   b   4  of the fly-eye lens  52 B, and changes of the optical paths of the light incident on the lens cells  51   b   1 ,  52   b   2 ,  52   b   3 , and  52   b   4  (dashed lines). These lens cell  51   b   1 ,  52   b   2 ,  52   b   3 , and  52   b   4  have respective radii of curvature R 1 , R 2 , R 3 , and R 4 . These radii of curvature have a magnitude relationship represented by R 1 &gt;R 2 &gt;R 3 &gt;R 4 .  FIG. 17  illustrates exemplary cross-sectional configurations of the four lens cells  51   c   1 ,  52   c   2 ,  52   c   3 , and  53   c   4  of the fly-eye lens  52 C, and changes of the optical paths of the light incident on the lens cells  51   c   1 ,  52   c   2 ,  52   c   3 , and  53   c   4  (dashed lines). These lens cells  51   c   1 ,  52   c   2 ,  52   c   3 , and  52   c   4  have respective on-axis thicknesses t 1 , t 2 , t 3 , and t 4 . These on-axis thicknesses have a magnitude relationship represented by t 1 &gt;t 2 &gt;t 3 &gt;t 4 .  FIG. 18  illustrates exemplary cross-sectional configurations of the four lens cells  51   d   1 ,  52   d   2 ,  52   d   3 , and  52   d   4  of the fly-eye lens  52 D, and changes of the optical paths of the light incident on the lens cells  51   d   1 ,  52   d   2 ,  52   d   3 , and  52   d   4  (dashed lines). These lens cells  51   d   1 ,  52   d   2 ,  52   d   3 , and  52   d   4  have respective material refractive indices n 1 , n 2 , n 3 , and n 4 . These material refractive indices have a magnitude relation represented by n 1 &gt;n 2 &gt;n 3 &gt;n 4 . 
       FIGS. 19A to 19C  illustrate exemplary arrangements of the four lens cells different from each other in any one of parameters in the plane of the fly-eye lens including the lens pitch (P), the radius of curvature (R), the on-axis thickness (t), and the material refractive index (n), and an effective diameter (dashed line). The references X 1 , X 2 , X 3 , and X 4  in these drawings indicate areas in which respective lens cells assigned with references having identical numbers at the end are arranged. For example, in a case where the fly-eye lens is configured by, for example, the lens cells  51   a   1 ,  52   a   2 ,  52   a   3 , and  52   a   4  having different lens pitches (P), the lens cell  51   a   1  having a lens pitch P 1  is arranged in X 1 , the lens cell  51   a   2  having a lens pitch P 2  is arranged in X 2 , the lens cell  51   a   3  having a lens pitch P 3  is arranged in X 3 , and the lens cell  51   a   4  having a lens pitch P 4  is arranged in X 4 . Accordingly, as illustrated in  FIG. 15 , for example, the fly-eye lens  52 A is obtained which exhibits an illumination light intensity distribution having a maximum intensity at its central portion. 
     Note that it is sufficient that the exemplary arrangement of the lens cells in the plane of the fly-eye lens has a configuration that allows the intensity distribution illustrated in  FIG. 15  to be obtained, and that the exemplary arrangement of the lens cells is not limited to the three examples illustrated in  FIGS. 19A to 19C . 
     ( 3 - 2 . Workings and Effects) 
     The output unit  50  in the image display apparatus  3  includes the illumination range control unit  52  configured by the fly-eye lens (the fly-eye lens  52 A,  52 B,  52 C, or  52 D) including the four lens cells different from each other in any one of the lens pitch (P), the radius of curvature (R), the on-axis thickness (t), and the material refractive index (n). Accordingly, it is possible to project the image light Li having a larger intensity distribution in the central portion than in the peripheral portion to the reflection mirror  15 . 
       FIG. 20  illustrates the illumination light intensity distribution of image light Limo incident on the optical modulator  1300  in the typical image display apparatus illustrated in, for example,  FIG. 8 . When the image light Limo, which has a uniform intensity distribution as described above, is projected to the full circumference screen, the full circumference screen has a luminance distribution in which the luminance decreases with distance from the reflection mirror  1500 , as illustrated in  FIG. 21 . Thus, in the typical image display apparatus provided with a full-circumference screen, an image projected to the screen is bright at its top but dark at its bottom. 
     In contrast, in the image display apparatus  3  of the present embodiment, the fly-eye lens (the fly-eye lens  52 A,  52 B,  52 C, or  52 D) including the four lens cells different from each other in any one of the lens pitch (P), the radius of curvature (R), the on-axis thickness (t), and the material refractive index (n) is used as the illumination range control unit  52 , and the image light Li having a larger intensity distribution in the central portion than in the peripheral portion is projected to the reflection mirror  15 , as illustrated in  FIG. 15 . Accordingly, the luminance of the screen  20  become uniform regardless of the position (height), as illustrated in  FIG. 22 . Therefore, it is possible to improve the image quality. 
     Note that, in the present embodiment, the fly-eye lens used as the illumination range control unit  52  is exemplified as the fly-eye lens  52 A including the four lens cells  51   a   1 ,  52   a   2 ,  52   a   3 , and  52   a   4  having different lens pitches (P), the fly-eye lens  52 B including the four lens cells  51   b   1 ,  52   b   2 ,  52   b   3 , and  52   b   4  having different radii of curvature (R), the fly-eye lens  52 C including the four lens cells  51   c   1 ,  52   c   2 ,  52   c   3 , and  52   c   4  having different on-axial thicknesses (t), and the fly-eye lens  52 C including the four lens cells  51   d   1   52   d   2 ,  52   d   3 , and  52   d   4  having different material refractive indices (n). The configuration of the fly-eye lens used as the illumination range control unit  52 , however, is not limited to these examples. 
     For example, although the fly-eye lens includes the four lens cells different from each other in any one of the lens pitch (P), the radius of curvature (R), the on-axis thickness (t), and the material refractive index (n) in the above-described embodiment, the fly-eye lens may include, for example, two lens cells, three lens cells, or five or more lens cells. Alternatively, the fly-eye lens may include a plurality of lens cells different from each other in all of the lens pitch (P), the radius of curvature (R), the on-axis thickness (t), and the material refractive index (n). 
     Further, the outer shapes of the lens cells of the fly-eye lens (e.g., the fly-eye lens  52 A,  52 B,  52 C, or  52 D) used as the illumination range control unit  52  preferably have the aspect ratios substantially the same as the aspect ratio of the outer shape of the reflection mirror  15 , as in the first embodiment described above. Accordingly, it is possible to improve the illumination efficiency of the reflection mirror  15  while reducing the difference in luminance between the top and the bottom of the screen  20 , resulting in a further improvement in the image quality. 
     Furthermore, although the intensity distribution in the plane of the illumination range S has a larger intensity in its central portion than in its peripheral portion in the present embodiment, the illumination range control unit  52  may be configured such that the intensity distribution has a maximum intensity in the peripheral portion around the central portion. Using the illumination range control unit  52  having such a intensity distribution further improves the illumination efficiency of the image light Li and further improves the image quality. 
     Described next is an optical system of the output unit (e.g., the output unit  10 ) in each of the image display apparatuses  1  to  3  according to the first embodiment described above, for example. 
     4. Example of Optical System of Image Display Apparatus 
     Configuration Example 1 
       FIG. 23  illustrates an optical system (an output unit  10 A) of a single-plate reflective liquid crystal image display apparatus (e.g., the image display apparatus  1 ) that performs light modulation using a reflective liquid crystal panel (LCOS). The output unit  10 A includes light source sections  100 R,  100 G, and  100 B respectively corresponding to RGB, coupling lenses  111 R,  111 G, and  111 B, dichroic prisms  112  and  113 , a fly-eye lens  114 , a main condensing lens  115 , a channel condensing lens  116 , a polarizing beam splitter (PBS)  117 , and an LCOS  118 . 
     The light source sections  100 R,  100 G, and  100 B output, for example, laser beams respectively corresponding to the colors RGB constituting the image light Li. For instance, the light source sections  100 R,  100 G, and  100 B correspond to the light source  11  in the first embodiment described above. A green light beam Lg outputted from the light source section  100 G is incident on the dichroic prism  112  after passing through the coupling lens  111 G, and is reflected from the dichroic prism  112  toward the dichroic prism  113 . A blue light beam Lb outputted from the light source section  100 B passes through the coupling lens  111 G and the dichroic prism  112 , and is outputted toward the dichroic prism  113 . A red light beam Lr outputted from the light source section  100 R is incident on the dichroic prism  113  after passing through the coupling lens  111 R. 
     The dichroic prism  113  selectively transmits the green light beam Lg and the blue light beam Lb and selectively reflects the red light beam Lr. The dichroic prism  113  combines the red light beam Lr, the green light beam Lg, and the blue light beam Lb into image light Li, and outputs the image light Li toward the fly-eye lens  114 . 
     The fly-eye lens  114  corresponds to, for example, the illumination range control unit  12  in the first embodiment described above, and controls the illumination range of the image light Li. The image light Li is adjusted by the fly-eye lens  114  such that the illumination range S of the image light Li has an aspect ratio substantially the same as the aspect ratio of the reflection mirror  15  before being outputted toward the main condensing lens  115 . The main condensing lens  115  and the channel condensing lens  116  transmit the light (the image light Li) outputted from the fly-eye lens  114  and condense the light on the LCOS  118 . 
     The LCOS  118  converts the polarization of the image light Li passing through the main condensing lens  115 , the channel condensing lens  116 , and the PBS  117 , and outputs the resultant light toward the PBS  117 . The image light Li reflected from the LCOS  118  and incident on the PBS  117  is reflected from the PBS  117  and outputted toward the projector lens  119 . 
     Although not illustrated, the projector lens  119  has a plurality of lens or the like, for example. The projector lens  119  corresponds to, for example, the projector lens  14  of the first embodiment described above. The projector lens  119  enlarges the image light Li into the predetermined illumination range S and projects the light to the reflection mirror  15 . 
     Configuration Example 2 
       FIG. 24  illustrates an optical system (an output unit  10 B) of a reflective 3LCD image display apparatus (e.g., the image display apparatus  1 ) that performs light modulation using a reflective liquid crystal panel (LCOS). The output unit  10 B includes a light source section  100 , an illumination optical system  210 , an image forming section  220 , and a projection optical system  230 . 
     Like the light source sections  100 R,  100 G,  100 B in Configuration Example 1 described above, the light source section  100  is configured by, for example, a solid-state light source, such as a semiconductor laser or a light emitting diode (LED), that outputs laser beams respectively corresponding to the colors RGB constituting the image light Li. Alternatively, the light source section  100  may be configured by, for example, a halogen lamp, a metal halide lamp, or a xenon lamp. Still alternatively, the light source section  100  may be configured by the combination of a solid-state light source that emits excitation light or a laser beam and a wavelength conversion unit such as a phosphor wheel from a position near the light source section  100 . 
     The illumination optical system  210  includes, for example, a fly-eye lens  211 , a polarization converting element  212 , a lens  213 , dichroic mirrors  214 A and  214 B, reflection mirrors  215 A and  215 B, lenses  216 A and  216 B, a dichroic mirror  217 , and polarizing plates  218 A to  218 C. 
     The fly-eye lens  211  corresponds to, for example, the illumination range control unit  12  in the first embodiment described above, and controls the illumination range of the image light Li. The polarization converting element  212  serves to align the polarization axis of incident light in a predetermined direction. For example, the polarization converting element  212  converts light other than P-polarized light into P-polarized light. The lens  213  focuses the light outputted from the polarization converting element  212  toward the dichroic mirrors  214 A and  214 B. 
     The dichroic mirrors  214 A and  214 B selectively reflect light having a wavelength within a predetermined wavelength range and selectively transmit light having a wavelength outside the predetermined wavelength range. For example, the dichroic mirror  214 A mainly reflects the red light beam Lr toward the reflection mirror  215 A. Additionally, the dichroic mirror  214 B reflects mainly the blue light beam Lb toward the reflection mirror  215 B. Thus, the green light beam Lg mainly passes through both the dichroic mirrors  214 A and  214 B and is directed toward a reflective polarizing plate  221 C (described below) of the image forming section  220 . 
     The reflection mirror  215 A reflects light outputted from the dichroic mirror  214 A (mainly the red light beam Lr) toward the lens  216 A, while the reflection mirror  215 B reflects light outputted from the dichroic mirror  214 B (mainly the blue light beam Lb) toward the lens  216 B. The lens  216 A transmits light outputted from the reflection mirror  215 A (mainly the red light beam Lr) and focuses the light to the dichroic mirror  217 . The lens  216 B transmits light (mainly the blue light beam Lb) outputted from the reflection mirror  215 B and focuses the light to the dichroic mirror  217 . 
     The dichroic mirror  217  selectively reflects green light beam Lg and selectively transmits light having a wavelength other than that of the green light beam Lg. Here, the dichroic mirror  217  transmits a red light component of the light received from the lens  216 A. In a case where the light received from lens  216 A contains a green light component, the dichroic mirror  217  reflects the green light component toward a polarizing plate  280 C. The polarizing plates  218 A to  218 C each include a polarizer having a polarization axis oriented in a predetermined direction. For example, the polarizing plates  218 A to  218 C transmit the P-polarized light obtained as the result of the conversion by the polarization converting element  212 , and reflect S-polarized light. 
     The image forming section  220  includes reflective polarizing plates  221 A to  221 C, reflective liquid crystal panels  222 A to  222 C (the optical modulator  13 ), and a dichroic prism  223 . 
     The reflective polarizing plates  221 A to  221 C transmit light (e.g., P-polarized light) having the same polarization axis as the polarization axis of the polarized light emitted from the polarizing plates  218 A to  218 C, and reflect light having another polarization axis (S-polarized light). Specifically, the reflective polarizing plate  221 A transmits P-polarized red light emitted from the polarizing plate  218 A toward the reflective liquid crystal panel  222 A. A reflective polarizer  221 B transmits P-polarized blue light emitted from the polarizing plate  218 B toward the reflective liquid crystal panel  222 B. The reflective polarizing plate  221 C transmits P-polarized green light emitted from the polarizing plate  218 C toward the reflective liquid crystal panel  222 C. Further, the P-polarized green light having passed through both the dichroic mirrors  214 A and  214 B and having been incident on the reflective polarizing plate  221 C passes through the reflective polarizing plate  221 C as it is, and enters the dichroic prism  223 . Further, the reflective polarizer  221 A reflects the S-polarized red light emitted from the reflective liquid crystal panel  222 A so that the S-polarized red light is incident on the dichroic prism  223 . The reflective polarizer  221 B reflects the S-polarized blue light emitted from the reflective liquid crystal panel  222 B so that the S-polarized blue light is incident on the dichroic prism  223 . The reflective polarizing plate  221 C reflects the S-polarized green light emitted from the reflective liquid crystal panel  222 C so that the S-polarized green light is incident on the dichroic prism  223 . 
     The reflective liquid crystal panels  222 A to  222 C perform spatial modulation of red light beam Lr, blue light beam Lb, and green light beam Lg, respectively. The dichroic prism  223  combines the red light beam Lr, the blue light beam Lb and the green light beam Lg incident thereon, and outputs the combined light toward the projection optical system  230 . 
     Although not illustrated, the projection optical system  230  includes, for example, a plurality of lenses or the like. The projection optical system  230  enlarges the output light (the image light Li) entering from the image forming section  220  into the predetermined illumination range S, and projects the light to the reflection mirror  15 . 
     Configuration Example 3 
       FIG. 25  is a schematic diagram illustrating an exemplary configuration of an optical system (an output unit  10 C) of a transmissive 3LCD image display apparatus (e.g., the image display apparatus  1 ) that performs light modulation using a transmissive liquid crystal panel. The output unit  10 C includes, for example, a light source section  100 , an image generating system  300  including an illumination optical system  310  and an image generating section  330 , and a projection optical system  340 . Note that the light source section  100  includes, for example, the same configuration as the light source section  100  in Configuration Example 2. 
     The illumination optical system  310  includes, for example, a fly-eye lens  311 , a polarization converting element  312 , and a condensing lens  313 . The fly-eye lens  311  corresponds to, for example, the illumination range control unit  12  in the first embodiment described above, and controls the illumination range of the image light Li. The polarization converting element  312  serves to align the polarization state of incident light entering through the fly-eye lens  311  or the like. The polarization converting element  312  outputs output light including blue light beam Lb, green light beam Lg, and red light beam Lr via a lens disposed on an output side of the light source section  100 , for example. 
     The illumination optical system  310  further includes dichroic mirrors  314  and  315 , mirrors  316 ,  317 , and  318 , relay lenses  319  and  320 , field lenses  321 R,  321 G, and  321 B, liquid crystal panels  331 R,  331 G and  331 B serving as the image generating section  330 , and a dichroic prism  332 . 
     The dichroic mirrors  314  and  315  each have a property of selectively reflecting color light having a wavelength within a predetermined wavelength range and transmitting light having a wavelength outside the predetermined wavelength range. For example, the dichroic mirror  314  selectively reflects the red light beam Lr. The dichroic mirror  315  selectively reflects the green light beam Lg out of the green light beam Lg and the blue light beam Lb having passed through the dichroic mirror  314 . The remaining blue light beam Lb passes through the dichroic mirror  315 . The light outputted from the light source section  100  is thereby separated into a plurality of color light beams of different colors. 
     The red light beam Lr obtained as the result of the separation is reflected by the mirror  316 , parallelized while passing through the field lens  321 R, and incident on the liquid crystal panel  331 R that modulates red light. The green light beam Lg is parallelized while passing through the field lens  321 G and incident on the liquid crystal panel  331 G that modulates green light. The blue light beam Lb passes through the relay lens  319  and is reflected from the mirror  317 , and further passes through the relay lens  320  and is reflected from the mirror  318 . The blue light beam Lb reflected from the mirror  318  is parallelized while passing through the field lens  321 B and incident on the liquid crystal panel  331 B that modulates blue light beam Lb. 
     The liquid crystal panels  331 R,  331 G, and  331 B are electrically coupled to a non-illustrated signal source (e.g., a PC or the like) that supplies image signals containing image information. The liquid crystal panels  331 R,  331 G, and  331 B modulate the incident light per pixel on the basis of the supplied image signals of respective colors, and respectively generate red, green, and blue images. The modulated color light beams (the generated images) are incident on the dichroic prism  332  and combined. The dichroic prism  332  superimposes or combines the color light beams incident from the three directions, and emits the combined light toward the projection optical system  340 . 
     Although not illustrated, the projection optical system  340  includes, for example, a plurality of lens or the like, as in Configuration Example 2. The projection optical system  340  enlarges the output light (the image light Li) entering from the image generating system  300  into the predetermined illumination range S, and projects the light to the reflection mirror. 
     In Configuration Examples 1 to 3 described above, the exemplary configuration of the output unit  10  ( 10 A to  10 C) is described that uses the LCOS  118 , the reflective liquid crystal panels  222 A to  222 C, or the transmissive liquid crystal panels  331 A to  331 C as the optical modulator  13 . The present technology, however, may also be applied to an image display apparatus using a DMD or a MEMS mirror. 
     Configuration Example 4 
       FIG. 26  is a schematic diagram illustrating an exemplary optical system (an output unit  10 D) of a DLP projector (e.g., the image display apparatus  1 ) using a DMD. The output unit  10 D includes a fly-eye lens  411 , a main condensing lens  412 , a channel condensing lens  413 , an internal totally-reflective prism (TIR prism)  414 , a DMD  415 , and a projector lens  416 . Note that the light source section  100  has, for example, the same configuration as the light source section  100  in Configuration Example 2. 
     Configuration Example 5 
       FIG. 27  is a block diagram illustrating an overall configuration of a projector (e.g., the image display apparatus  1 ) using a MEMS mirror. The projector has a controller  511 , a laser driver  512  that controls the light source sections (laser light source sections)  100 R,  100 G, and  100 B, and a mirror driver  513  that controls a MEMS mirror  517 . The projector further includes a reflection mirror  514 , polarization converting elements  515  and  516 , a MEMS mirror  517 , and a plurality of lenses  518  and  519 . The present technology may also be applied to an image display apparatus using a MEMS mirror in a case were the illumination range control unit described above (e.g., the illumination range control unit  12 ) is disposed between the polarization converting element  516  and the MEMS mirror  517 . 
     The present disclosure has been described above with reference to the first and second embodiments and the modification examples. The present disclosure, however, is not limited to the embodiments and the like described above and may be modified in various ways. 
     Further, the screen (e.g., the screen  20 ) displays a 2D image in the above embodiment or the like. The present technology, however, may be applied to an image display apparatus capable of displaying a 3D image. 
     Note that the effects described herein are not necessarily limitative, and any effect described in the present disclosure may be made. 
     Note that the present disclosure may also be configured as follows. According to the present technology having the following configurations, the second optical member is disposed in the output unit including the light source. The second optical member adjusts the illumination range of projection light to be incident on the first optical member such that the illumination range has an aspect ratio substantially the same as the aspect ratio of the outer shape of the first optical member. The first optical member controls the incident angle of the projection light to be incident on the irradiation target member. This improves the utilization efficiency of the projection light. Therefore, it is possible to improve the image quality. 
     (1) An image display apparatus including: 
     an output unit including a light source and outputting projection light outputted from the light source along a predetermined axis; 
     an irradiation target member to be irradiated with the projection light; 
     a first optical member disposed opposite to the output unit along the predetermined axis and controlling an incident angle of the projection light to be incident on the irradiation target member; and 
     a second optical member included in the output unit and adjusting an illumination range of the projection light to be incident on the first optical member such that the illumination range has an aspect ratio substantially the same as an aspect ratio of an outer shape of the first optical member. 
     (2) The image display apparatus according to (1) described above, in which the second optical member adjusts the illumination range of the projection light such that the illumination range is in close contact with a periphery of the outer shape of the first optical member.
 
(3) The image display apparatus according to (1) or (2) described above, in which
 
     the first optical member has a substantially circular outer shape, and 
     the illumination range of the projection light incident on the first optical member has a peripheral portion in close contact with at least any four points on a circumference of the first optical member. 
     (4) The image display apparatus according to any one of (1) to (3) described above, in which the second optical member applies a larger intensity distribution to a central portion of the projection light outputted from the light source than to a peripheral portion of the projection light, and emits the projection light.
 
(5) The image display apparatus according to any one of (1) to (3) described above, in which the second optical member applies an intensity distribution having a maximum intensity at a peripheral portion around a central portion to the projection light outputted from the light source, and emits the projection light.
 
(6) The image display apparatus according to any one of (1) to (5) described above, in which the second optical member is a fly-eye lens including a plurality of lens cells each having a square, pentagonal, or higher polygonal shape.
 
(7) The image display apparatus according to (6) described above, in which the fly-eye lens includes a plurality types of lens cells different from each other in any one of a lens pitch, a radius of curvature, an on-axis thickness, and a material refractive index.
 
(8) The image display apparatus according to any one of (1) to (5) described above, in which the second optical member is a rod integrator lens having a cylindrical, quadrangular, or higher polygonal prismatic shape.
 
(9) The image display apparatus according to any one of (1) to (5) described above, in which the second optical member is a holographic optical element that transmits and scatters the projection light.
 
(10) The image display apparatus according to (9) described above, in which the holographic optical element is a volume type hologram or a surface-relief hologram.
 
(11) The image display apparatus according to any one of (1) to (5) described above, in which the second optical member is a diffuser plate in which fine particles are diffused.
 
(12) The image display apparatus according to any one of (1) to (5) described above, in which the second optical member is a micro electro mechanical system (MEMS) mirror.
 
(13) The image display apparatus according to any one of (1) to (12) described above, in which the projection light is incident on the irradiation target member at an incident angle of 40° or greater and 75° or less.
 
(14) The image display apparatus according to any one of (1) to (13) described above, in which the light source is any one of a semiconductor laser, a light emitting diode, a halogen lamp, a metal halide lamp, and a xenon lamp.
 
(15) The image display apparatus according to any one of (1) to (14) described above, in which the irradiation target member is a transmissive screen having a light transmitting property or a reflective screen.
 
(16) The image display apparatus according to (15) described above, in which the screen is any one of a hologram screen, a Fresnel screen, and a scattering particle screen.
 
(17) The image display apparatus according to any one of (1) to (16) described above, in which the irradiation target member is disposed over an entire circumference around the output unit.
 
(18) The image display apparatus according to any one of (1) to (17), in which the irradiation target member has a cylindrical shape.
 
     This application claims the priority of Japanese Patent Application No. 2019-086535 filed with the Japanese Patent Office on Apr. 26, 2019, the entire contents of which are incorporated herein by reference. 
     Those skilled in the art could conceive of various modifications, combinations, sub-combinations, and changes in accordance with design requirements and other factors. However, it is understood that they are included within the scope of the appended claims or the equivalents thereof.