Image display device and projection optical system

Abstract

This projection optical system for an image display device has a lens system and a concave reflective surface. The lens system is formed based on a reference axis, at a position to which generated image light is incident, and has a positive refractive power overall. The concave reflective surface is formed based on the reference axis and reflects the image light emitted from the lens system toward an object to be projected. In addition, the projection optical system is configured to satisfy the relationship 0<|Δθ(hmax)-Δθ(0.9•hmax)| / θ(hmax)<0.056, where: h is the light beam height from the reference axis; θ(h) is the angle between the direction of the light beam height and a tangent line of a function Z(h) indicating the shape of the concave reflective surface according to the beam height h; Δθ(h) is the amount of change in the angle θ(h) in the light beam height h; and hmax is the light beam height h of a reflection point farthest separate from the reference axis of the concave reflective surface that reflects the image light.

Description

Technical Field

[0001] The present technology relates to an image display device such as a projector and a projection optical system, for example.

Background Art

[0002] Conventionally, a projector is widely known as a projection-type image display device that displays a projected image on a screen. Recently, there has been an increasing demand for an ultra-wide-angle front projection type projector that can display a large screen even in a small projection space. By using this projector, it is possible to project a large screen in a limited space by hitting it obliquely and at a wide angle with respect to the screen.

[0003] In the ultra-wide-angle projection type projector described in Patent Document 1, it is possible to perform screen shift that moves the projected image projected on the screen by moving some of the optical components included in the projection optical system. By using this screen shift, fine adjustment of the image position and the like can be easily performed (paragraphs

[0023]

[0024] etc. of the specification of Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] It is considered that projectors compatible with ultra-wide angles will continue to spread in the future, and technologies capable of realizing high-quality image display are required.

[0006] In view of the above circumstances, an object of the present technology is to provide an image display device and a projection optical system that can support ultra-wide angles and can realize high-quality image display.

Means for Solving the Problems

[0007] To achieve the above object, an image display device according to one embodiment of the present technology includes a light source, an image generation unit, and a projection optical system. The image generation unit generates image light by modulating the light emitted from the light source. The projection optical system has a lens system and a concave reflecting surface. The lens system is configured with respect to a reference axis at a position where the generated image light is incident, and has a positive refractive power as a whole. The concave reflecting surface is configured with respect to the reference axis, and reflects the image light emitted from the lens system toward the object to be projected. Further, the image display device Let the height of the light ray from the reference axis be h, Let the angle of the tangent of the function Z(h) representing the shape of the concave reflecting surface corresponding to the light ray height h with respect to the optical axis height direction be θ(h), Let the change amount of the angle θ(h) at the light ray height h be Δθ(h), When the light ray height h of the reflection point farthest from the reference axis of the concave reflecting surface that reflects the image light is set as hmax, 0 < |Δθ(hmax) - Δθ(0.9·hmax)| / θ(hmax) < 0.056 It is configured to satisfy the relationship.

[0008] In this image display device, the shape of the concave reflecting surface that reflects the image light toward the object to be projected is designed as described above. Thereby, it becomes possible to realize high-quality image display.

[0009] The Δθ(h) may be θ(h) - θ(0.98·h).

[0010] Among the image light, when the light rays whose reflection points reflected by the concave reflecting surface are included in a range larger than 0.85·hmax are defined as edge-side light rays, the projection optical system may be configured such that the traveling directions of the respective edge-side light rays incident on the concave reflecting surface are parallel to each other.

[0011] The projection optical system may be configured such that the ray intervals of the edge-side rays incident on the concave reflecting surface are equal.

[0012] The lens system may include a first refractive optical system, a first reflecting surface, a second reflecting surface, and a second refractive optical system. The first refractive optical system has a positive refractive power as a whole and refracts the generated image light. The first reflecting surface reflects the image light refracted by the first refractive optical system by folding it back. The second reflecting surface reflects the image light reflected by the first reflecting surface by folding it back. The second refractive optical system has a positive refractive power as a whole and refracts the image light reflected by the second reflecting surface and emits it to the concave reflecting surface. Further, the image display device Let the power of the first reflecting surface be Φ1, and the power of the second reflecting surface be Φ2. Then, 0.1 < |Φ2 / Φ1| < 1.2 It may be configured to satisfy the relationship.

[0013] The image display device may be configured to satisfy the relationship |Φ2| < |Φ1|. Further, the image display device Let the first refractive optical system, the first reflecting surface, and the second reflecting surface be the first optical system, and the portion of the second refractive optical system that acts on the edge-side rays be the second optical system. Then, The first optical system may condense the edge-side rays at a predetermined condensing position. Further, the predetermined condensing position may coincide with the front focal position of the second optical system.

[0014] The image display device Among the edge-side rays, the ray whose ray height at the reflection point reflected by the concave reflecting surface is an intermediate value is defined as the intermediate ray. The incident position of the intermediate light ray on the final lens surface of the second refractive optical system is defined as the intermediate incident position. The optical path length from the image generation unit of the intermediate light ray to the predetermined condensing position is A. The optical path length from the intermediate incident position to the front focal position is B. Assuming that the optical path length from the image generation unit of the intermediate light ray to the intermediate incident position is C, 0.8 < |A + B| / C < 1.2 It may be configured to satisfy the relationship.

[0015] The average value of the angles at which the traveling directions of the edge-side light rays incident on the concave reflecting surface intersect with the direction along the reference axis is defined as the average angle. Assuming that the region of the final lens surface of the second refractive optical system where the edge-side light rays are incident is defined as the edge-side incident region, The front focal position of the second optical system may be the condensing position when parallel light rays are incident from the opposite side of the edge-side incident region of the final lens surface along the direction intersecting at the average angle with respect to the direction along the reference axis.

[0016] The optical path length B may be the optical path length of the light ray traveling from the intermediate incident position to the rear focal position when parallel light rays are incident from the opposite side of the edge-side incident region of the final lens surface.

[0017] The concave reflecting surface may reflect at least a part of the light rays included in the image light incident on the concave reflecting surface in a direction intersecting with the direction along the reference axis at an angle of 90 degrees or more.

[0018] The projection optical system may include a first optical component in which a part of the principal surface is configured as the first reflecting surface and a transmissive surface is configured in another region of the principal surface. In this case, the transmissive surface of the first optical component may function as the second refractive optical system.

[0019] The projection optical system may include a second optical component in which a part of the principal surface is configured as the second reflection surface and a transmission surface is configured in another region of the principal surface. In this case, the transmission surface of the second optical component may function as the first refractive optical system.

[0020] The reference axis may be an axis obtained by extending the optical axis of the lens closest to the image generation unit included in the lens system.

[0021] The projection optical system may be configured such that the optical axes of all the optical components included in the projection optical system coincide with a predetermined reference axis.

[0022] The concave reflecting surface may be configured such that the axis of rotational symmetry coincides with the reference axis. In this case, each of the first reflecting surface and the second reflecting surface may be a concave reflecting surface and may be configured such that the axis of rotational symmetry coincides with the reference axis.

[0023] Each of the concave reflecting surface, the first reflecting surface, and the second reflecting surface may be configured such that the optical axis coincides with the reference axis. In this case, at least one of the concave reflecting surface, the first reflecting surface, or the second reflecting surface may be a free-form surface having no axis of rotational symmetry.

[0024] The object to be projected may be a flat screen or a curved screen.

[0025] The object to be projected may be a screen having a dome shape.

[0026] A projection optical system according to an aspect of the present technology is a projection optical system that projects image light generated by modulating light emitted from a light source, and includes the lens system and the concave reflecting surface.

Brief Description of the Drawings

[0027]

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[0028] Hereinafter, embodiments according to the present technology will be described with reference to the drawings.

[0029] [Outline of a Projection-Type Image Display Device] The outline of a projection-type image display device will be briefly described by taking a liquid crystal projector as an example. A liquid crystal projector forms an optical image (image light) corresponding to a video signal by spatially modulating the light irradiated from a light source. For light modulation, a liquid crystal display element or the like, which is an image modulation element, is used. For example, a three-panel liquid crystal projector equipped with panel-shaped liquid crystal display elements (liquid crystal panels) corresponding to each of RGB is used.

[0030] The optical image is enlarged and projected by a projection optical system and displayed on a screen. Here, the projection optical system will be described as corresponding to an ultra-wide angle with a half angle of 70° or more, for example. Of course, it is not limited to this angle.

[0031] In a liquid crystal projector corresponding to an ultra-wide angle, a large screen can be displayed even in a small projection space. That is, even when the distance between the liquid crystal projector and the screen is short, enlarged projection is possible. Thereby, the following advantages are exhibited. Since the liquid crystal projector can be placed close to the screen, it is possible to sufficiently suppress the possibility that the light from the liquid crystal projector directly enters the human eye, and high safety is exhibited. Since no shadow of a human or the like is reflected on the screen, an efficient presentation is possible. The degree of freedom in selecting the installation location is high, and it can be easily installed even on a narrow installation space or a ceiling with many obstacles. By installing and using it on the wall, maintenance such as cable routing is easier than when installed on the ceiling. For example, it is possible to increase the degree of freedom in settings such as meeting spaces, classrooms, and conference rooms.

[0032] FIG. 1 is a schematic diagram for explaining another advantage of the liquid crystal projector compatible with an ultra-wide angle. As shown in FIG. 1, by installing the liquid crystal projector 1 compatible with an ultra-wide angle on the table, it becomes possible to project an enlarged image 2 on the same table. Such a usage is also possible, and the space can be used efficiently.

[0033] Recently, with the spread of electronic blackboards (Interactive White Board) etc. in schools, workplaces, etc., the demand for liquid crystal projectors compatible with ultra-wide angles has been increasing. Also, the same type of liquid crystal projector is used in fields such as digital signage (electronic advertising). For example, as an electronic blackboard, it is also possible to use technologies such as LCD (Liquid Crystal Display) and PDP (Plasma Display Panel). By using a liquid crystal projector compatible with an ultra-wide angle compared with these technologies, it is possible to provide a large screen at a reduced cost. Note that the liquid crystal projector compatible with an ultra-wide angle is also called a short-focus projector, an ultra-short-focus projector, etc.

[0034] FIG. 2 is a schematic diagram showing a configuration example of a projection type image display device. The image display device 20 includes a light source 5, an illumination optical system 10, and a projection optical system 15. The light source 5 is arranged to emit a light beam toward the illumination optical system 10. As the light source 5, for example, a high-pressure mercury lamp or the like is used. Alternatively, a solid light source such as an LED (Light Emitting Diode) or an LD (Laser Diode) may be used.

[0035] The illumination optical system 10 is configured to uniformly irradiate the surface of an image modulation element (liquid crystal panel P) that serves as a primary image plane with the light beam emitted from the light source 5. In the illumination optical system 10, the light beam from the light source 5 sequentially passes through two fly-eye lenses FL, a polarization conversion element PS, and a condenser lens L, and is converted into a uniform light beam with aligned polarization. The light beam that has passed through the condenser lens L is separated into the respective RGB color component lights by a dichroic mirror DM that reflects only light in a specific wavelength band. The respective RGB color component lights are incident on a liquid crystal panel P (image modulation element) provided corresponding to each RGB color through a total reflection mirror M, a lens L, or the like. Then, each liquid crystal panel P performs light modulation according to a video signal. The light-modulated respective color component lights are combined by a dichroic prism PP to generate image light. Then, the generated image light is emitted toward the projection optical system 15.

[0036] The optical components and the like constituting the illumination optical system 10 are not limited, and optical components different from those described above may be used. For example, as the image modulation element, instead of the transmissive liquid crystal panel P, a reflective liquid crystal panel, a digital micromirror device (DMD), or the like may be used. Also, for example, instead of the dichroic prism PP, a polarization beam splitter (PBS), a color synthesis prism that synthesizes RGB color video signals, or a TIR (Total Internal Reflection) prism may be used. In the present embodiment, the illumination optical system 10 corresponds to an image generation unit.

[0037] The projection optical system 15 adjusts the image light emitted from the illumination optical system 10 and performs enlarged projection onto a screen that serves as a secondary image plane. That is, the projection optical system 15 adjusts the image information of the primary image plane (liquid crystal panel P) and enlarges and projects it onto the secondary image plane (screen).

[0038] <First Embodiment> [Image Display System] FIGS. 3 and 4 are schematic views showing a configuration example of an image display system according to the first embodiment of the present technology. FIG. 3 is a view of the image display system 100 seen from above. FIG. 4 is a view of the image display system 100 obliquely seen from above on the upper right front side.

[0039] The image display system 100 includes a curved screen 30 and two image display devices 20. The curved screen 30 includes both a screen whose overall shape is a curved surface shape and a screen whose shape of at least a part is a curved surface shape. As shown in FIGS. 3 and 4, in the present embodiment, a curved screen 30 having a substantially arc shape is used when viewed from above. The curved screen 30 is erected along the vertical direction and installed so as to extend in the horizontal direction. The left and right end portions 31a and 31b of the curved screen 30 are bent forward and arranged at substantially equal positions in the front-rear direction. The substantially central portion of the curved screen 30 in the horizontal direction is located on the rearmost side and corresponds to the apex of the substantially arc shape when viewed from above.

[0040] It is also possible to express the shape of the curved screen 30 as being substantially equal to a part of the inner surface of a cylinder erected along the vertical direction. Further, the curved screen 30 may be configured by connecting minute plane regions while changing the angles between them. The specific configurations such as the material, size, and radius of curvature of the curved screen 30 are not limited and may be arbitrarily designed. Further, the curved screen 30 may be realized by adhering a flexible screen member to the inner surface of the base portion having an arc shape when viewed from above. In the present embodiment, the curved screen 30 corresponds to the object to be projected.

[0041] The two image display devices 20 are composed of a first image display device 20a and a second image display device 20b. The first image display device 20a is installed at a substantially central portion in the vertical direction of the left end portion 31a of the curved screen 30 so as to be able to project an image rearward. The first image display device 20a projects an image (hereinafter referred to as the first image) 21a onto the left region of the curved screen 30 bent in a substantially arc shape. The second image display device 20b is installed at a substantially central portion in the vertical direction of the right end portion 31b of the curved screen 30 so as to be able to project an image rearward. The second image display device 20b projects an image (hereinafter referred to as the second image) 21b onto the right region of the curved screen 30 bent in a substantially arc shape. As shown in FIGS. 3 and 4, the first and second image display devices 20a and 20b project the first and second images 21a and 21b such that the first and second images 21a and 21b overlap each other. Note that a holding mechanism (not shown) for holding the first and second image display devices 20a and 20b may be arbitrarily designed.

[0042] In the present embodiment, the image modulation elements (liquid crystal panels P) provided in the first and second image display devices 20a and 20b have a rectangular shape having a long side direction and a short side direction. Then, image light constituting a rectangular image is generated by the liquid crystal panel P. The first and second images 21a and 21b are respectively projected as rectangular images equal to each other. Then, the first and second images 21a and 21b are respectively projected so as to overlap each other along the long side direction (left - right direction) of the first and second images 21a and 21b. Therefore, in the approximate center portion of the curved screen 30, an overlapping region 22 where the first and second images 21a and 21b overlap with each other is generated.

[0043] In this embodiment, stitching processing is executed in the overlapping region 22 where the first and second images 21a and 21b overlap. As a result, the first and second images 21a and 21b are connected and synthesized as one image. As a result, one large-sized image is displayed in substantially the entire region along the left-right direction of the curved screen 30. The specific algorithm or the like of the stitching process is not limited, and any stitching technique may be used.

[0044] In FIG. 3, the first image light 23a that constitutes the first image 21a projected from the first image display device 20a, and the pixel lights Ca1, Ca2, and Ca3 included in the first image light 23a are schematically illustrated. Also in FIG. 3, the first image light 23b that constitutes the second image 21b projected from the second image display device 20b, and the pixel lights Cb1, Cb2, and Cb3 included in the second image light 23b are schematically illustrated. Note that the pixel light is light for constituting each of a plurality of pixels included in the projected image. Typically, light emitted from each of the plurality of pixels included in the image modulation element (liquid crystal panel P) that generates and emits the image light becomes the pixel light. Therefore, the image light includes a plurality of pixel lights.

[0045] The pixel light Ca1 shown in FIG. 3 is pixel light for constituting a pixel at the left end of the first image 21a. Therefore, the pixel light Ca1 corresponds to the light beam at the left end of the first image light 23a. The pixel light Ca2 is pixel light for constituting a pixel at the right end of the first image 21a. Therefore, the pixel light Ca2 corresponds to the light beam at the right end of the first image light 23a. The pixel light Ca3 is pixel light for constituting a pixel at the left end of the overlapping region 22 where the first and second images 21a and 21b overlap. Therefore, among the light rays included in the first image light 23a, the light rays from the pixel light Ca3 to Ca2 become the image light that constitutes the overlapping region 22. On the other hand, among the light rays included in the first image light 23a, the light rays from the pixel light Ca1 to Ca3 become the image light that constitutes the region other than the overlapping region 22.

[0046] The pixel light Cb1 shown in FIG. 3 is the pixel light for constituting the pixels at the right end portion of the second image 21b. Therefore, the pixel light Cb1 corresponds to the light rays at the right end portion of the second image light 23b. The pixel light Cb2 is the pixel light for constituting the pixels at the left end portion of the second image 21b. Therefore, the pixel light Cb2 corresponds to the light rays at the left end portion of the first image light 23a. The pixel light Ca3 is the pixel light for constituting the pixels at the right end portion of the overlapping region 22. Therefore, among the light rays included in the second image light 23b, the light rays from the pixel light Cb3 to Cb2 become the image light that constitutes the overlapping region 22. On the other hand, among the light rays included in the second image light 23b, the light rays from the pixel light Cb1 to Cb3 become the image light that constitutes the region other than the overlapping region 22.

[0047] As shown in FIG. 3, in the present embodiment, the first and second image display devices 20a and 20b project the first and second images 21a and 21b such that the image light that constitutes the regions other than the overlapping region 22 where the first and second images 21a and 21b overlap with each other does not cross each other. Thereby, it is possible to sufficiently suppress the occurrence of the shadow of the user 3 standing at a position close to the overlapping region 22 generated in the substantially central portion of the curved screen 30. As a result, the user 3 can view the first and second images 21a and 21b synthesized into one from the region inside the curved screen 30 bent in an arc shape (for example, a position close to the overlapping region 22). Thereby, it is possible to realize a very high sense of immersion in the content, and it is possible to provide an excellent visual effect to the user 3.

[0048] The directions in which the first and second images 21a and 21b overlap are not limited. For example, the first and second images 21a and 21b may be projected along the short side directions of the first and second images 21a and 21b so as to overlap each other. For example, in the configuration examples shown in FIGS. 3 and 4, rectangular first and second images 21a and 21b having the left-right direction as the short side direction are projected. Then, the first and second images 21a and 21b may be projected along the short side directions of the first and second images 21a and 21b so that the first and second images 21a and 21b overlap.

[0049] Depending on the shape of the curved screen 30, when image light constituting a rectangular image is projected, the image may be displayed in a shape different from the rectangular shape. In this case, for example, it is possible to define the directions corresponding to the long side direction and the short side direction of the liquid crystal panel P as the long side direction and the short side direction of the image. And it is possible to overlap a plurality of images along the long side direction or the short side direction. In the present disclosure, there may be cases where the long side direction and the short side direction of the liquid crystal panel P are expressed as the long side direction and the short side direction of the image light.

[0050] In the present embodiment, as the first and second image display devices 20a and 20b, image display devices having substantially the same configuration as each other are used. Hereinafter, the projection optical system 15 of the first and second image display devices 20a and 20b will be described.

[0051] [Projection Optical System] FIGS. 5 and 6 are optical path diagrams showing schematic configuration examples of the projection optical system 15 according to the present embodiment. In FIG. 6, one projection optical system 15 and a portion on which an image of the curved screen S is projected are shown. By combining two configurations of FIG. 6 to be symmetric with each other, it is possible to realize the image display system 100 having the curved screen 30 and the first and second image display devices 20a and 20b shown in FIGS. 3 and 4. Also, in FIGS. 5 and 6, the liquid crystal panel P and the dichroic prism PP of the illumination optical system 10 are schematically illustrated.

[0052] Hereinafter, the emission direction of the image light emitted from the dichroic prism PP to the projection optical system 15 is defined as the Z direction. Also, the horizontal direction of the primary image plane (liquid crystal panel P) is defined as the X direction, and the vertical direction is defined as the Y direction. The X and Y directions correspond to the horizontal and vertical directions of the image formed by the image light. For the sake of convenience, when viewing the projection optical system from the side, the Z direction (emission direction of the image light) in the figure may be described as the left - right direction, and the Y direction as the up - down direction in some explanations. Of course, regarding the application of this technology, the emission direction of the image light and the like are not limited, and the orientation and posture of the image display device 20 can be arbitrarily set. Also, in FIGS. 5 and 6, the cross - sectional shapes of the optical surfaces (such as lens surfaces and reflection surfaces) of the respective optical components included in the projection optical system 15 are illustrated. On the other hand, for simplicity of illustration, hatching and the like representing the cross - sections of the respective optical components are omitted.

[0053] The projection optical system 15 includes a lens system L and a concave reflecting surface Mr3. The lens system L is configured at the position where the image light generated by the illumination optical system 10 is incident, and has a positive refractive power as a whole. The lens system L is configured with reference to a reference axis extending in the Z direction (hereinafter, this reference axis is referred to as the optical axis O). In the present embodiment, the lens system L is configured such that the optical axes of one or more optical components included in the lens system L substantially coincide with the optical axis O which is the reference axis. Note that the optical axis of an optical component is typically an axis passing through the center of the optical surface of the optical component. For example, when the optical surface of an optical component has a rotational symmetry axis, the rotational symmetry axis corresponds to the optical axis. In some cases, only a part including the effective region, which is the region where the image light is incident, of an optical component arranged such that its own optical axis coincides with the optical axis O may be used. By using a part of the optical component, it is possible to reduce the size of the projection optical system 15.

[0054] In this embodiment, the optical axis O is an axis obtained by extending the optical axis (axis of rotational symmetry) of the lens L11 that is closest to the illumination optical system 10 and is included in the optical system L. That is, other optical components are arranged on the axis obtained by extending the optical axis of the lens L11. Note that the image light is emitted along the optical axis O from a position offset upward from the optical axis O. It is also possible to refer to the Z direction along the optical axis O as the optical path propagation direction of the lens system L.

[0055] As shown in FIG. 5, the lens system L includes a first refractive optical system L1, a first reflecting surface Mr1, a second reflecting surface Mr2, and a second refractive optical system L2. The first refractive optical system L1 has a positive refractive power as a whole and refracts the image light generated by the illumination optical system 10. In this embodiment, from the incident surface F1 on which the image light of the lens L11 disposed at the position closest to the illumination optical system 10 is incident, to the exit surface F2 from which the image light of the lens L12 disposed at the position closest to the first reflecting surface Mr1 is emitted, functions as the first refractive optical system L1.

[0056] The first reflecting surface Mr1 is a concave reflecting surface and is a rotationally symmetric aspherical surface configured such that the axis of rotational symmetry coincides with the optical axis O. The first reflecting surface Mr1 is disposed below the optical axis O and reflects the image light refracted by the first refractive optical system L1 by folding it back. Specifically, the image light incident from the left side is reflected by folding it back upward to the left. As shown in FIG. 5, in this embodiment, the first optical component R11 is arranged such that the axis of rotational symmetry coincides with the optical axis O. The first reflecting surface Mr1 is formed in a partial region below the rotationally symmetric aspherical surface F3 corresponding to the principal surface of the first optical component R11. Conversely, a partial region below the rotationally symmetric aspherical surface F3 is configured as the first reflecting surface Mr1. A transmission surface Tr2 is formed in another region of the rotationally symmetric aspherical surface F3 of the first optical component R11.

[0057] The second reflecting surface Mr2 is a concave reflecting surface and is a rotationally symmetric spherical surface configured such that the axis of rotational symmetry coincides with the optical axis O. The second reflecting surface Mr2 is disposed above the optical axis O, reflects the image light reflected by the first reflecting surface Mr1, and reflects it toward the second refractive optical system L2. Specifically, the image light incident from the lower right is reflected back toward the right. As shown in FIG. 5 in the present embodiment, the second optical component R12 is disposed such that the axis of rotational symmetry coincides with the optical axis O. The second reflecting surface Mr2 is formed in a partial region above the rotationally symmetric surface F4 corresponding to the main surface of the second optical component R12. Conversely, a partial region above the rotationally symmetric surface F4 is configured as the second reflecting surface Mr2. A transmissive surface Tr1 is formed in another region of the rotationally symmetric surface F4 of the second optical component R12.

[0058] In the present embodiment, the transmissive surface Tr2 formed on the rotationally symmetric aspherical surface F3 of the first optical component R11 functions as the second refractive optical system L2. Also, the transmissive surface Tr1 formed on the rotationally symmetric surface F4 of the second optical component R12 functions as the first refractive optical system L1. In this way, one optical component realizes the first reflecting surface Mr1 and the optical surface (transmissive surface Tr2) that functions as the second refractive optical system L2. Also, the second reflecting surface Mr2 and the optical surface (transmissive surface Tr1) that functions as the first refractive optical system L1 are realized. Thereby, it becomes possible to reduce the size of the projection optical system 15. Also, it becomes possible to improve the assembly accuracy of the projection optical system 15.

[0059] The second refractive optical system L2 has a positive refractive index as a whole, refracts the image light reflected by the second reflecting surface Mr2, and emits it to the concave reflecting surface Mr3. In the present embodiment, the portion from the transmissive surface Tr2 formed on the first optical component R11 to the exit surface F5 from which the image light of the lens L21 disposed closest to the concave reflecting surface Mr3 exits functions as the second refractive optical system L2. The exit surface F5 of the lens L21 serves as the final lens surface of the second refractive optical system L2. Hereinafter, the exit surface F5 may be described as the final lens surface F5 using the same reference numeral.

[0060] The concave reflecting surface Mr3 is configured with respect to the optical axis O which is the reference axis, and reflects the image light emitted from the lens system L toward the curved screen S. The concave reflecting surface Mr3 is a rotationally symmetric aspherical surface configured such that the axis of rotational symmetry (optical axis) coincides with the optical axis O, and is composed only of a portion capable of reflecting the effective region which is the region where the image light is incident. That is, instead of disposing the entire rotationally symmetric aspherical surface, only the necessary portion of the rotationally symmetric aspherical surface is disposed. This makes it possible to miniaturize the apparatus.

[0061] In the present embodiment, a first refractive optical system L1, a first reflecting surface Mr1, a second reflecting surface Mr2, a second refractive optical system L2, and a concave reflecting surface Mr3 are configured on the common optical axis O. Therefore, the first refractive optical system L1, the first reflecting surface Mr1, the second reflecting surface Mr2, the second refractive optical system L2, and the concave reflecting surface Mr3 are configured such that the axis obtained by extending the optical axis (axis of rotational symmetry) of the lens L11 disposed closest to the illumination optical system 10 coincides with each optical axis. Thus, in the present embodiment, the optical axes of all the optical components included in the projection optical system 15 are configured to coincide with the optical axis O. This makes it possible to reduce the size in the Y direction and to miniaturize the apparatus. However, the present invention is not limited to this, and optical components whose optical axes are offset from the optical axis O may be included in the projection optical system 15.

[0062] With reference to FIGS. 5 and 6, the optical path of the image light will be described. In FIGS. 5 and 6, the optical paths of three pixel lights C1, C2, and C3 among the image light emitted from the dichroic prism PP to the projection optical system 15 are illustrated. Note that the pixel light is emitted as divergent light from the pixels of the liquid crystal panel P. The emitted pixel light is imaged on the curved screen S by the projection optical system 15 and is displayed as a pixel of the projected image. In the present disclosure, the component light emitted along the optical axis O (along the Z direction) of each pixel light is defined as the chief ray. Each pixel light is imaged at a position where the chief ray is incident on the curved screen S. In FIG. 5, for each pixel light, the chief ray and the maximum upper and lower divergent lights are illustrated.

[0063] The pixel light C1 corresponds to the pixel light emitted from the central pixel of the liquid crystal panel P. The pixel light C2 corresponds to the pixel light emitted from the pixel closest to the optical axis O at the center of the liquid crystal panel P. The pixel light C3 corresponds to the pixel light emitted from the pixel farthest from the optical axis O at the center of the liquid crystal panel P. That is, in the present embodiment, the pixel light C2 corresponds to the pixel light emitted from the pixel closest to the optical axis O of the liquid crystal panel P. Also, the pixel light C3 is located on the straight line connecting the pixel closest to the optical axis O to the central pixel of the liquid crystal panel P and corresponds to the pixel light emitted from the pixel farthest from the optical axis O.

[0064] As shown in FIG. 5, the image light emitted from a position offset upward from the optical axis O along the optical axis O enters the projection optical system 15, intersects the optical axis O within the first refractive optical system L1, proceeds downward, and enters the first reflecting surface Mr1. The image light incident on the first reflecting surface Mr1 is reflected by the first reflecting surface Mr1, intersects the optical axis O again, proceeds upward, and enters the second reflecting surface Mr2. The image light incident on the second reflecting surface Mr2 is reflected by the second reflecting surface Mr2 and enters the second refractive optical system L2. Within the second refractive optical system L2, the image light intersects the optical axis O again, proceeds downward, and is emitted toward the concave reflecting surface Mr3. The image light emitted from the second refractive optical system L1 is reflected upward by the concave reflecting surface Mr3, intersects the optical axis O again, and is projected toward the curved screen S.

[0065] Thus, in this embodiment, the optical path of the image light is configured to intersect the optical axis O. As a result, it becomes possible to configure the optical path of the image light up to the concave reflecting surface Mr3 in the vicinity of the optical axis O. As a result, it becomes possible to reduce the size of the apparatus in the Y direction, and it becomes possible to reduce the size of the apparatus. Also, by each of the first reflecting surface Mr1 and the second reflecting surface Mr2, the image light is reflected back. As a result, it becomes possible to sufficiently secure the optical path length of the image light. As a result, it becomes possible to reduce the size of the apparatus in the X direction, and it becomes possible to reduce the size of the apparatus.

[0066] Also, in the projection optical system 15 according to this embodiment, a plurality of intermediate images (not shown) are formed between the dichroic prism PP included in the illumination optical system 10 and the concave reflecting surface Mr3. The intermediate image is an intermediate image of an image composed of image light. As a result, it becomes possible to project the image light at an ultra-wide angle. For example, even when the distance between the projector and the screen is short, it is possible to display a large screen. In order to form a high-precision image on the screen by the concave reflecting surface Mr3, it is important to optically and appropriately correct the image generated by the illumination optical system 10 and guide it to the concave reflecting surface Mr3. In this embodiment, since it is possible to sufficiently secure the optical path length of the image light by the first reflecting surface Mr1 and the second reflecting surface Mr2, it is possible to accurately perform the optical correction of the image. That is, it becomes possible to generate an appropriate intermediate image, and it becomes possible to easily form a high-precision image on the screen. Also, since the optical path length is sufficiently secured, it becomes possible to suppress the optical load necessary for generating an appropriate intermediate image, and it becomes possible to suppress the optical power of each optical component included in the projection optical system 15. As a result, it becomes possible to reduce the size of each optical component, and it becomes possible to realize the reduction of the size of the entire apparatus. In addition, since a plurality of intermediate images are formed in the projection optical system 15, it is possible to accurately generate an optimal intermediate image. As a result, it becomes possible to display a highly accurate image on the screen by the concave reflecting surface Mr3. By using the projection optical system 15 according to the present embodiment in this way, it is possible to realize high performance of the apparatus.

[0067] As shown in FIGS. 5 and 6, in the present embodiment, by the concave reflecting surface Mr3, at least some of the light rays included in the image light incident on the concave reflecting surface Mr3 are reflected in a direction intersecting at an angle of 90 degrees or more with the direction along the optical axis O which is the reference axis. Note that the intersection angle between the traveling direction of the light rays included in the image light reflected by the concave reflecting surface Mr3 and the direction along the optical axis O is defined as follows. First, the intersection point between the straight line extending along the optical axis O and the straight line extending along the traveling direction of the light rays reflected by the concave reflecting surface Mr3 is calculated. The straight line extending from the intersection point toward the liquid crystal panel P side is rotated toward the traveling direction side of the light rays with the intersection point as a reference. At this time, the rotation angle until the straight line extending toward the liquid crystal panel P side coincides with the straight line extending along the traveling direction of the light rays is defined as the intersection angle between the traveling direction of the light rays included in the image light reflected by the concave reflecting surface Mr3 and the direction along the optical axis O. In the present embodiment, the concave reflecting surface Mr3 is designed such that the intersection angle defined above of at least some of the light rays included in the image light reflected by the concave reflecting surface Mr3 is 90 degrees or more.

[0068] In the example shown in FIG. 5, the pixel light C3 included in the image light is reflected in a direction intersecting at an angle of 90 degrees or more with the direction along the optical axis O. The intersection angle R1 of this image light C3 is the maximum intersection angle. That is, the pixel light C3 is the light ray having the largest intersection angle. The other light rays are reflected in a direction intersecting at an angle smaller than the intersection angle R1 with respect to the direction along the optical axis O. Here, pixel light is taken as an example of the light rays included in the image light. However, it is not limited to this, and at least some of the light rays, such as some of the light rays included in the pixel light, may be reflected in a direction that intersects at an angle of 90 degrees or more with the direction along the optical axis O. The image display device 20 including the projection optical system 15 as illustrated in FIGS. 5 and 6 is installed such that the concave reflecting surface Mr3 is disposed at a position corresponding to the shape of the curved screen S. By designing the concave reflecting surface Mr3 so that the intersection angle becomes large, it becomes possible to realize high-quality image display corresponding to the curved screen S.

[0069] The present inventor focused on the principal rays of each pixel light included in the image light with respect to image display using the concave reflecting surface Mr3, and repeatedly studied the behavior of the principal rays. Then, the following configuration conditions were newly found for the configuration of the projection optical system 15. FIG. 7 is a schematic diagram showing the optical path of the pixel light (principal ray) included in the image light. Although there are parts in FIG. 7 that are different from the illustration of the projection optical system 15 shown in FIG. 5, the behavior of the pixel light (principal ray) is the same. Hereinafter, in explaining the results of the study, "light ray" shall mean "pixel light". Also, descriptions such as "light ray" and "pixel light" shall mean the principal ray of "pixel light". For example, descriptions such as the traveling direction of the light ray (pixel light), the incident position of the light ray (pixel light), the reflection point of the light ray (pixel light) reflected by the reflecting surface, the reflection angle of the light ray (pixel light) reflected by the reflecting surface, and the ray height of the light ray (pixel light) shall mean the traveling direction of the principal ray, the incident position of the principal ray, the reflection point of the principal ray, the reflection angle of the principal ray, the ray height of the principal ray, and the like.

[0070] (Configuration Condition 1) FIG. 8 is a schematic diagram for explaining Configuration Condition 1. As shown in FIG. 8, let the ray height from the optical axis O, which is the reference axis, be h. Let the angle of the tangent of the function Z(h) representing the shape of the concave reflecting surface Mr3 corresponding to the ray height h with respect to the optical axis height direction be θ(h). As shown in Fig. 8, the optical axis height direction is the direction (Y direction) orthogonal to the optical axis O. Also, the slope of the tangent line of the function Z(h) can be calculated by the derivative Z'(h) obtained by differentiating the function Z(h) with respect to the ray height h. Using the derivative Z'(h), the angle θ(h) can be calculated. Let Δθ(h) be the change amount of the angle θ(h) at the ray height h. Let hmax be the ray height of the reflection point RPmax that is farthest from the optical axis O on the concave reflecting surface Mr3 that reflects the image light. The ray height hmax is the ray height of the reflection point of the ray that is incident at the position farthest from the optical axis O among the rays incident on the concave reflecting surface Mr3. In this case, the projection optical system 15 is configured so as to satisfy the following relationship. (1) 0 < |Δθ(hmax) - Δθ(0.9·hmax)| / θ(hmax) < 0.056

[0071] This conditional expression (1) defines the amount of change in the shape in the region where the ray height h of the concave reflecting surface Mr3 is large (hereinafter referred to as the edge side region). Specifically, it defines the amount of change in the shape in the region from the optical axis height hmax to the optical axis height 0.9·hmax. The rays reflected in the edge side region of the concave reflecting surface Mr3 constitute the edge side region of the image projected onto the curved screen S. When |Δθ(hmax) - Δθ(0.9·hmax)| / θ(hmax) exceeds the upper limit defined by the conditional expression (1), the amount of change in the shape of the edge side region of the concave reflecting surface Mr3 increases, and the uniformity of the luminance (brightness) and magnification of the edge side region of the projected image decreases. When |Δθ(hmax) - Δθ(0.9·hmax)| / θ(hmax) exceeds the lower limit defined by the conditional expression (1), that is, when the amount of change in the shape of the edge side region of the plane reflecting surface Mr3 is 0, the uniformity of the luminance and magnification of the edge side region of the projected image also decreases. The concave reflecting surface Mr3 is configured to satisfy the conditional expression (1). That is, for the light rays whose reflection points reflected by the concave reflecting surface Mr3 are included in the range from the optical axis height hmax to 0.9·hmax, the shape change of the concave reflecting surface Mr3 is designed to be gentle. Thereby, it becomes possible to improve the uniformity of the luminance and magnification in the edge side region of the projected image, and it becomes possible to realize high-quality image display.

[0072] As shown in FIG. 8, in the present embodiment, Δθ(h) is θ(h) - θ(0.98·h). Of course, it is not limited to this, and other parameters representing the change amount Δθ(h) of the angle θ(h) at the light ray height h may be used.

[0073] (Configuration condition 2) FIG. 9 is a schematic diagram for explaining the configuration condition 2. As shown in FIG. 9, among the image light, the light rays whose reflection points reflected by the concave reflecting surface Mr3 are included in the range larger than 0.85·hmax are defined as the edge side light rays CE. The projection optical system 15 is configured such that the traveling directions of the respective edge side light rays CE incident on the concave reflecting surface Mr3 are parallel to each other. That is, the projection optical system 15 is configured such that the edge side light rays CE incident on the concave reflecting surface Mr3 become parallel light rays. Thereby, it becomes possible to improve the uniformity of the luminance and magnification in the edge side region of the projected image.

[0074] (Configuration condition 3) The projection optical system 15 is configured such that the ray intervals of the edge side light rays CE incident on the concave reflecting surface Mr3 are equal. This can also be said that the reflection points of the respective edge side light rays CE on the concave reflecting surface Mr3 are arranged at equal intervals. Thereby, it becomes possible to improve the uniformity of the luminance and magnification in the edge side region of the projected image.

[0075] (Configuration condition 4) Let the power of the first reflecting surface Mr1 be Φ1. Let the power of the second reflecting surface Mr2 be Φ2. In this case, the projection optical system 15 is configured to satisfy the following relationship. (2) 0.1 < |Φ2 / Φ1| < 1.2

[0076] This conditional expression (2) defines the relationship between the power Φ1 of the first reflecting surface Mr1 and the power Φ2 of the second reflecting surface Mr2. When |Φ2 / Φ1| exceeds the upper limit defined by the conditional expression (2), the light rays reflected by the first reflecting surface Mr1 and the light rays reflected by the second reflecting surface Mr2 interfere with each other. When |Φ2 / Φ1| is less than the lower limit defined by the conditional expression (2), the light rays reflected by the second reflecting surface Mr2 do not properly enter the second refractive optical system L2. That is, the light rays reflected by the second reflecting surface Mr2 do not properly enter the transmission surface Tr2 of the first optical component R11. By configuring the first reflecting surface Mr1 and the second reflecting surface Mr2 so as to satisfy the conditional expression (2), it becomes possible to properly guide the image light to the concave reflecting surface Mr3. As a result, it becomes possible to realize high-quality image display.

[0077] (Configuration condition 5) FIG. 10 is a schematic diagram for explaining Configuration condition 5. The projection optical system 15 is configured to satisfy the following relationship. (3) |Φ2| < |Φ1| As shown in FIG. 10, in order for the above-described (Configuration condition 2) to be satisfied, it is necessary to apply a large refractive power to the light rays with a large ray height h (particularly the light rays with a ray height hmax) in the second refractive optical system L2. When the conditional expression (3) is not satisfied, that is, when |Φ2| ≧ |Φ1|, in order to apply a large refractive power to the light rays with a ray height hmax, for example, as shown in FIG. 9A, it is conceivable to design the distance between the second reflecting surface Mr2 and the second refractive optical system L2 to be large. However, if the distance between the second reflecting surface Mr2 and the second refractive optical system L2 is increased, the projection optical system 15 becomes large-sized. Alternatively, as shown in FIG. 9B, it is also conceivable to increase the power of the second refractive optical system L2. However, increasing the power of the second refractive optical system L2 makes it easier for aberration to occur in the projected image, and there is a high possibility that the image quality will deteriorate. As shown in FIG. 9C, the first reflecting surface Mr1 and the second reflecting surface Mr2 are configured to satisfy the conditional expression (2). Thereby, it becomes possible to greatly reflect the light beam with the light beam height hmax upward. Therefore, it becomes possible to emit the light beam height hmax at an angle from the upper side from the second reflecting surface Mr2 toward the second refractive optical system L2. As a result, it becomes possible to apply a large refractive power to the light beam with the light beam height hmax. Therefore, it becomes possible to achieve downsizing of the apparatus and suppression of aberration while satisfying (Configuration Condition 2). Conversely, it becomes possible to satisfy (Configuration Condition 2) without increasing the size of the projection optical system 15 and without causing aberration in the projected image.

[0078] (Configuration Condition 6-1) FIGS. 11 to 13 are schematic diagrams for explaining Configuration Condition 6. The first refractive optical system L1, the first reflecting surface Mr1, and the second reflecting surface Mr2 are defined as the first optical system LL1. That is, from the incident surface F1 of the lens L11 to the second reflecting surface Mr2 is the first optical system LL1. The portion that acts on the marginal ray of the second refractive optical system L2 is defined as the second optical system LL2. That is, when the portion through which the marginal ray CE travels in the second refractive optical system L2 is regarded as one optical system, the optical system is the second optical system LL2. The projection optical system 15 is configured such that the first optical system L1 converges the marginal ray CE to a predetermined converging position 35. The projection optical system 15 is also configured such that the converging position 35 coincides with the front focal position 36 of the second optical system LL2. That is, the projection optical system 15 is configured such that the first optical system LL2 converges the marginal ray CE to the front focal position 36 of the second optical system LL2.

[0079] Referring to FIG. 12, the front focal position 36 of the second optical system LL2 will be described. The average value of the angles at which the traveling directions (the incident directions on the concave reflecting surface Mr3) of the edge-side rays CE incident on the concave reflecting surface Mr3 intersect with the direction along the optical axis O is defined as the average angle θ1. The region of the final lens surface F5 of the second refractive optical system L2 where the edge-side ray CE is incident is defined as the edge-side incident region 37. As shown in FIG. 12, the front focal position 36 of the second optical system LL2 is the converging position when parallel rays 38 are incident from the opposite side of the edge-side incident region 37 of the final lens surface F5 along the direction intersecting with the direction along the optical axis O at the average angle θ1.

[0080] (Configuration condition 6-2) (Configuration condition 6-2) will be described as a condition equivalent to (Configuration condition 6-1). As shown in FIGS. 11 and 13, among the edge-side rays CE, the ray with the ray height h at the reflection point reflected by the concave reflecting surface Mr3 being an intermediate value is defined as the intermediate ray 40. In FIGS. 11 and 13, the intermediate ray 40 is illustrated by a thick arrow. The incident position of the intermediate ray 40 on the final lens surface F5 of the second refractive optical system L2 is defined as the intermediate incident position 41. The optical path length from the illumination optical system 10 to the converging position 35 of the intermediate ray 40 is defined as A. Specifically, as shown in FIG. 13, the optical path length from the image modulation element (liquid crystal panel P) to the converging position 35 is the optical path length A. The optical path length from the intermediate incident position 41 to the front focal position 36 is defined as B. As shown in FIG. 12, the optical path length B is the optical path length of the ray (the thick-arrow ray in FIG. 12) traveling from the intermediate incident position 41 to the front focal position 36 when parallel rays 38 are incident from the opposite side of the edge-side incident region 37 of the final lens surface F5. The optical path length from the illumination optical system 10 to the intermediate incident position 41 of the intermediate ray 40 is defined as C. Specifically, as shown in FIG. 13, the optical path length from the image modulation element (liquid crystal panel P) to the intermediate incident position 41 is the optical path length C. In this case, the projection optical system 15 is configured to satisfy the following relationship. (4) 0.8 < |A + B| / C < 1.2 That is, in the present disclosure, as long as the range that satisfies the conditional expression (4) is satisfied, the condensing position 35 coincides with the front focal position 36, and it is assumed that (Configuration condition 6-1) is satisfied.

[0081] When |A + B| / C exceeds the upper limit defined in the conditional expression (4), the marginal ray CE emitted from the second refractive optical system L2 diverges and does not become a parallel ray. When |A + B| / C exceeds the lower limit defined in the conditional expression (4), the marginal ray CE emitted from the second refractive optical system L2 converges and does not become a parallel ray. The projection optical system 15 is configured so as to satisfy the conditional expression (4). That is, the projection optical system 15 is configured such that the condensing position 35 coincides with the front focal position 36. Thereby, it becomes possible to satisfy (Configuration condition 2), and it becomes possible to improve the uniformity of the luminance and magnification in the marginal region of the projected image.

[0082] In the projection optical system 15 of the present embodiment, the first intermediate image is formed between the dichroic prism PP included in the illumination optical system 10 and the first reflecting surface Mr1. Also, the second intermediate image is formed between the first reflecting surface Mr1 and the second reflecting surface Mr2. Furthermore, the third intermediate image is formed between the second refractive optical system L2 and the concave reflecting surface Mr3. And an image is formed on the screen by the concave reflecting surface Mr3. The first optical system LL1 can also be said to be the optical system on the front stage side with the second intermediate image as a boundary. Also, the second optical system LL2 can also be said to be the optical system on the rear stage side with the second intermediate image as a boundary. Of course, the application of this technology is not limited to the case where such an intermediate image is formed.

[0083] Also, in the present embodiment, the marginal ray CE is emitted from the liquid crystal panel P along the optical axis O. Therefore, the condensing position 35 where the marginal ray CE is condensed by the first optical system LL1 can also be said to be the rear focal position of the first optical system LL1. Therefore, in the present embodiment, with respect to (Configuration Condition 6-1) and (Configuration Condition 6-2), it is also possible to rephrase the condensing position 35 as the rear focal position of the first optical system LL1.

[0084] In configuring the projection optical system 15 according to the present technology, it is not necessarily required that all the configuration conditions listed above are satisfied. As long as at least one of the above configuration conditions is satisfied, it can function as an embodiment of the projection optical system according to the present technology. And it becomes possible to realize high-quality image display. Of course, all the configuration conditions may be satisfied. Alternatively, the projection optical system 15 may be configured such that any two or more of the configuration conditions are met.

[0085] The lower limit and upper limit values of each of the conditional expressions (1), (2), and (4) are not limited to the values described above. For example, depending on the configurations of the illumination optical system 10, the projection optical system 15, etc., it is also possible to appropriately change each value. For example, any value within the above-described range may be selected as the lower limit and upper limit values and set again as an optimal range.

[0086] For example, it is possible to set the conditional expression (1) within the following range. 0.01 < |Δθ(hmax) - Δθ(0.9·hmax)| / θ(hmax) < 0.06 0.02 < |Δθ(hmax) - Δθ(0.9·hmax)| / θ(hmax) < 0.05 0.03 < |Δθ(hmax) - Δθ(0.9·hmax)| / θ(hmax) < 0.04

[0087] For example, it is possible to set the conditional expression (2) within the following range. 0.05 < |Φ2 / Φ1| < 1.3 0.15 < |Φ2 / Φ1| < 1.15 0.2 < |Φ2 / Φ1| < 1.1

[0088] For example, it is possible to set the conditional expression (4) within the following range. 0.7 < |Φ2 / Φ1| < 1.3 0.9 < |Φ2 / Φ1| < 1.15 1.0 < |Φ2 / Φ1| < 1.1

[0089] For the projection optical system 15 configured as described above, a simple explanation will be given with specific numerical examples.

[0090] FIG. 14 is a table showing an example of parameters related to image projection. FIG. 15 is a schematic diagram for explaining the parameters shown in FIG. 14. The numerical aperture NA on the primary image plane side of the projection optical system 15 is 0.127. The lengths (H × VSp) in the horizontal and vertical directions of the image modulation element (liquid crystal panel P) are 15.6 mm and 8.7 mm, respectively. The center position (Chp) of the image modulation element is at a position 5.6 mm above the optical axis O. The image circle (imc) on the primary image plane side is φ26.3 mm. As shown in FIG. 15, pixel light C1 shown in FIG. 5 etc. is emitted from the central pixel of the liquid crystal panel P (referred to as pixel C1 using the same reference numeral). Pixel light C2 is emitted from the pixel closest to the optical axis O at the center of the liquid crystal panel P (referred to as pixel C2 using the same reference numeral). Pixel light C3 is emitted from the pixel farthest from the optical axis O at the center of the liquid crystal panel P (referred to as pixel C3 using the same reference numeral).

[0091] Regarding the configuration conditions for the marginal side ray CE, it is possible to give the same configuration conditions for the rays defined using the image circle (imc). For example, as shown in FIG. 16, for the image circle (imc) of the maximum image height, an image circle (0.74·imc) of 74% of the image height is defined. The rays emitted from the region from the image circle of 74% of the image height to the image circle (imc) of the maximum image height (the region shown in gray in the figure) are defined as high image height emitted rays. The following configuration conditions apply to the high image height emitted rays. The projection optical system 15 is configured such that the high image height output light beam becomes a parallel light beam and is incident on the concave reflecting surface Mr3 (condition corresponding to configuration condition 2). The projection optical system 15 is configured such that the high image height output light beam is incident on the concave reflecting surface Mr3 at equal ray intervals (condition corresponding to configuration condition 3). In the portions of the first optical system LL1 and the second refractive optical system L2 that act on the high image height output light beam, as illustrated in FIG. 13, the condensing position 35 coincides with the front focal position 36 (condition corresponding to configuration condition 6-1). In the portions of the first optical system LL1 and the second refractive optical system L2 that act on the high image height output light beam, the conditional expression (4) is satisfied (condition corresponding to configuration condition 6-2). By configuring the projection optical system 15 so as to satisfy these configuration conditions regarding the high image height output light beam, the same effects as described above are exhibited. That is, it becomes possible to improve the uniformity of the luminance and magnification in the edge side region of the projected image, and it becomes possible to realize high-quality image display. Note that the high image height output light beam group and the edge side light beam group may be the same light beam group or may be different light beam groups.

[0092] FIG. 17 shows the lens data of the image display device. FIG. 17 shows data regarding 1 to 33 optical components (lens surfaces) arranged from the primary image plane (P) side toward the secondary image plane (S) side and the curved screen S. As data for each optical component (lens surface), the radius of curvature (mm), the core thickness d (mm), the refractive index nd at the d-line (587.56 nm), and the Abbe number νd at the d-line are described. For the curved screen S, the radius of curvature (mm) is described.

[0093] Note that the optical component having an aspherical surface follows the following formula.

[0094]

Equation

[0095] FIG. 18 is a table showing an example of the aspherical coefficient of the optical components included in the projection optical system. FIG. 18 shows the aspherical coefficients for the respective aspherical optical components 19, 20, 21, 23, 24, and 33 to which asterisks were added in FIG. 17. The aspherical coefficients in the illustrated example correspond to the above formula (1). In this embodiment, formula (1) corresponds to the function Z(h) representing the shape of the concave reflecting surface Mr3 according to the ray height. When the ray height h is input into formula (1), the sag amount Z is used as a parameter representing the shape of the concave reflecting surface Mr3 according to the ray height. Note that the “sag amount” is the distance in the optical axis direction between the plane passing through the vertex of the surface and perpendicular to the optical axis and the point on the lens surface.

[0096] Note that the derivative Z'(h) (= dZ / dh) obtained by differentiating the function Z(h) with respect to the ray height is given by the following formula.

[0097]

Equation

[0098] From this formula, the slope of the straight line tangent to the concave reflecting surface Mr3 at the ray height h is calculated. That is, it becomes possible to calculate the angle θ(h) of the tangent of the function Z(h) with respect to the optical axis height direction.

[0099] FIG. 19 is a graph showing the relationship between the ray height h and Δθ(h) / θ(hmax). Note that calculations are performed after normalizing with respect to the ray height h, with the ray height h of the optical axis O being 0 and the ray height hmax being 1. From the ray height of 0.9 to 1.00 away from the optical axis O, Δθ(h) / θ(hmax) changes gently. This means that the shape of the concave reflecting surface Mr3 changes gently in the edge side region from the ray height of (0.9·hmax) to (hmax). That is, it means that the shape of the reflecting surface changes gently with respect to the rays whose reflection points are from (0.9·hmax) to (hmax). This makes it possible to improve the luminance and magnification uniformity in the edge region of the projected image, and to realize high-quality image display. Note that |Δθ(hmax)-Δθ(0.9·hmax)| / θ(hmax) in conditional expression (1) is the difference between the value of the ray height 1.00 and the value of the ray height 0.9 in the graph shown in FIG. 19.

[0100] FIG. 20 is a table showing the numerical values of the parameters used in the above conditional expressions (1), (2), and (4) in the present embodiment. |Z'(1.0·hmax)-Z'(0.9·hmax)| 0.001 |Φ2 / Φ1| 0.370 |A + B| / C 1.004 As a result, it can be seen that conditional expressions (1), (2), and (4) are satisfied. Note that conditional expression (3) is also satisfied. In addition, in the present embodiment, all the configuration conditions 1 to 6 are satisfied. Note that in the present embodiment, conditional expression (4) holds for the light rays emitted from the region from the image circle at 59% of the image height to the image circle (imc) at the maximum image height. Therefore, it is also possible to define the light rays as high-image-height-emitted light rays.

[0101] As described above, in the image display device 20 according to the present embodiment, the shape of the concave reflecting surface Mr3 that reflects image light toward the object to be projected is designed as described above. This makes it possible to realize high-quality image display. In addition, in the image display device 20 according to the present embodiment, due to the concave reflecting surface Mr3, at least some of the light rays of the image light are reflected in a direction intersecting at an angle of 90 degrees or more with the direction along the optical axis O that is a reference in configuring the projection optical system 15. This makes it possible to, for example, correspond to the projection of an image onto a curved screen S or the like, and to realize high-quality image display. For example, consider a case where the same image light is projected onto a flat screen and a curved screen, respectively. Then, naturally, the image displayed on the flat screen and the image displayed on the curved screen will have different shapes. Considering the image displayed on the flat screen as a reference, the image displayed on the curved screen will be a distorted image. Therefore, in order to properly display an image on the curved screen, an electrical correction process must be performed on the image signal. The amount of correction depends on the shape of the curved screen, but it is often large, and there is a possibility that the image quality of the image may deteriorate. In addition, in order to display an image over a wide range of the curved screen, the image display device must be installed at a position away from the curved screen. As a result, for the user viewing the image, the presence of the image display device becomes conspicuous, and the sense of immersion in the content is impaired. Also, since the area where the user's shadow appears becomes large, the area where the user can move becomes small. As a result, it becomes difficult to provide an excellent viewing environment.

[0102] In the image display system 100 according to the present embodiment, the range that can be reflected by the concave reflecting surface Mr3 is designed to be 90 degrees or more with respect to the reference optical axis O, which is wide. As a result, it becomes possible to optically suppress the distortion of the image displayed on the curved screen S. As a result, it becomes possible to sufficiently suppress the amount of electrical correction for the image signal. As a result, it becomes possible to display an image with high image quality. Also, as illustrated in FIG. 3, since it is possible to project an image over a wide range of the curved screen S from a position close to the curved screen S, it is possible to sufficiently suppress the inhibition of the user 3's sense of immersion in the content due to the presence of the first and second image display devices 20a and 20b. Also, since it is possible to reduce the area where the shadow of the user 3 appears, the area where the user 3 can move can be increased. As a result, it becomes possible to provide a very excellent viewing environment.

[0103] <Second Embodiment> The image display system according to the second embodiment of the present technology will be described. In the following description, parts that are the same as the configurations and operations in the image display system 100 and the image display device 20 described in the above embodiment will be omitted or simplified in their description.

[0104] FIGS. 21 and 22 are optical path diagrams showing schematic configuration examples of the projection optical system 215 according to the second embodiment. FIG. 23 shows the lens data of the image display device. FIG. 24 is a table showing an example of the aspherical coefficient of the optical components included in the projection optical system. FIG. 25 is a graph showing the relationship between the ray height h and Δθ(h) / θ(hmax). Note that the parameters related to image projection are the same as those in the first embodiment and are the numerical values shown in FIG. 14.

[0105] Also in the projection optical system 215 according to the present embodiment, at least a part of the light rays included in the image light incident on the concave reflecting surface Mr3 is reflected by the concave reflecting surface Mr3 in a direction intersecting at an angle of 90 degrees or more with the direction along the optical axis O which is the reference axis. Thereby, it becomes possible to realize high-quality image display corresponding to the curved screen S.

[0106] FIG. 26 is a table showing the numerical values of the parameters used in the above conditional expressions (1), (2), and (4) in the present embodiment. |Z'(1.0·hmax)-Z'(0.9·hmax)| 0.003 |Φ2 / Φ1| 0.356 |A + B| / C 1.003 As a result, it can be seen that the conditional expressions (1), (2), and (4) are satisfied. Note that the conditional expression (3) is also satisfied. Also, in the projection optical system 215 according to the present embodiment, all the configuration conditions 1 to 6 are satisfied. Thereby, it becomes possible to improve the uniformity of the luminance and magnification in the edge side region of the projected image, and it becomes possible to realize high-quality image display. In this embodiment, the conditional expression (4) is satisfied for the light rays emitted from the region from the image circle at 59% of the image height to the image circle (imc) at the maximum image height. Therefore, it is also possible to define the light rays as high-image-height-emitted light rays.

[0107] <Third Embodiment> FIGS. 27 and 28 are optical path diagrams showing schematic configuration examples of the projection optical system 315 according to the third embodiment. FIG. 29 is a table showing an example of parameters related to image projection. FIG. 30 is lens data of an image display device. FIG. 31 is a table showing an example of the aspherical coefficients of the optical components included in the projection optical system. FIG. 32 is a graph showing the relationship between the ray height h and Δθ(h) / θ(hmax).

[0108] In this embodiment, image light is projected toward the flat screen S'. The concave reflecting surface Mr3 of the projection optical system 315 reflects the light rays included in the image light incident on the concave reflecting surface Mr3 in a direction intersecting with the direction along the optical axis O at an angle of less than 90 degrees. The present technology is also applicable to such an image display device.

[0109] FIG. 33 is a table showing the numerical values of the parameters used in the above conditional expressions (1), (2), and (4) in this embodiment. |Z'(1.0·hmax)-Z'(0.9·hmax)| 0.002 |Φ2 / Φ1| 0.455 |A+B| / C 0.972 As a result, it can be seen that the conditional expressions (1), (2), and (4) are satisfied. Note that the conditional expression (3) is also satisfied. In addition, in the projection optical system 315 according to this embodiment, all the configuration conditions 1 to 6 are satisfied. Thereby, it is possible to improve the uniformity of the luminance and magnification in the edge region of the projected image, and it is possible to realize high-quality image display. In this embodiment, the conditional expression (4) is satisfied for the light rays whose reflection points reflected by the concave reflecting surface Mr3 are included in the range larger than 0.82·hmax. Therefore, it is also possible to define the light rays as edge-side light rays. In this embodiment, the conditional expression (4) is satisfied for the light rays emitted from the region from the image circle at 71% of the image height to the image circle (imc) at the maximum image height. Therefore, it is also possible to define the light rays as high-image-height-emitted light rays.

[0110] <Fourth Embodiment> FIGS. 34 and 35 are optical path diagrams showing schematic configuration examples of the projection optical system 415 according to the fourth embodiment. FIG. 36 is a table showing an example of parameters related to image projection. FIG. 37 is lens data of the image display device. FIG. 38 is a table showing an example of the aspherical coefficients of the optical components included in the projection optical system. FIG. 39 is a graph showing the relationship between the ray height h and Δθ(h) / θ(hmax).

[0111] Also in this embodiment, image light is projected toward the flat screen S'. The concave reflecting surface Mr3 of the projection optical system 415 reflects the light rays included in the image light incident on the concave reflecting surface Mr3 in a direction intersecting with the direction along the optical axis O at an angle less than 90 degrees.

[0112] FIG. 40 is a table showing the numerical values of the parameters used in the above-described conditional expressions (1), (2), and (4) in this embodiment. |Z'(1.0·hmax)-Z'(0.9·hmax)| 0.004 |Φ2 / Φ1| 0.701 |A + B| / C 1.0388 As a result, it can be seen that the conditional expressions (1), (2), and (4) are satisfied. Note that the conditional expression (3) is also satisfied. In addition, in the projection optical system 315 according to this embodiment, all the configuration conditions 1 to 6 are satisfied. As a result, it becomes possible to improve the uniformity of the luminance and magnification of the edge side region of the projected image, and it becomes possible to realize high-quality image display. In this embodiment, the conditional expression (4) was satisfied for the light rays in which the reflection points reflected by the concave reflecting surface Mr3 are included in a range larger than 0.78·hmax. Therefore, it is also possible to define the light rays as edge side light rays.

[0113] <Other Embodiments> The present technology is not limited to the embodiments described above, and various other embodiments can be realized.

[0114] FIGS. 41 and 42 are schematic diagrams showing a configuration example of an image display system according to another embodiment. In the image display system 500 shown in FIG. 41, a curved screen S having a dome shape is used. The dome shape is not limited to a hemispherical shape, and includes any shape that can cover the upper part over 360 degrees around. The curved screen S having a dome shape can also be called a dome screen.

[0115] As shown in FIGS. 41A to C, below the dome-shaped curved screen S, the first and second image display devices 520a and 520b are installed so as to face each other along the left-right direction. The first and second image display devices 520a and 520b are installed so as to be able to project the first and second images 521a and 521b upward. The first and second images 521a and 521b are projected so as to overlap each other along the long side direction (left-right direction). Therefore, at the apex portion of the curved screen S, an overlapping region 522 in which the first and second images 521a and 521b overlap each other is generated. Stitching processing is executed based on the overlapping region 522, and one large-sized image is displayed. By using the image display device according to the present technology described above as the first and second image display devices 520a and 520b, it is possible to realize high-quality image display corresponding to the dome shape and provide an excellent viewing environment.

[0116] In the image display system 600 shown in FIG. 42, below the curved screen S having a dome shape, the first to third image display devices 620a to 620b are arranged at equal intervals along the circumference. The first to third image display devices 620a to 620c are installed so as to be able to project the first to third images 621a to 621c upward. As shown in FIG. 42B, image light for constituting a rectangular image is projected as the first to third images 621a to 621c. In FIG. 42B, each of the first to third images 621a to 621c is schematically shown in a rectangular shape, but the shape displayed on the curved screen S is different from a rectangular shape. The first and second of the first to third images 621a and 621b are projected so as to overlap each other at positions symmetric to each other with respect to the vertex of the curved screen S. Then, at the overlapping regions 622a to 622c, stitching processing is executed, and one large-sized image is displayed. By using the image display device according to the present technology described above as the first to third image display devices 620a to 620c, it is possible to realize high-quality image display corresponding to the dome shape and provide an excellent viewing environment. Thus, the present technology is applicable even when three or more image display devices are used.

[0117] As the concave reflecting surface that reflects image light on the screen, a free-form surface having no axis of rotational symmetry may be used. In this case, for example, the optical axis of the concave reflecting surface (for example, the axis passing through the center of the optical surface) is aligned with the reference axis that is a reference in configuring the lens system. Thereby, it is possible to exhibit the same effect as described above. For the first reflecting surface and the second reflecting surface as well, a free-form surface without a rotational symmetry axis may be used. That is, at least one of the concave reflecting surface, the first reflecting surface, or the second reflecting surface may be a free-form surface without a rotational symmetry axis.

[0118] The projection target is not limited to a curved screen. This technology is applicable to the display of images on any projection target, such as a wall of a table, a building, etc. In particular, high-quality image display corresponding to a projection target having a curved shape can be realized.

[0119] Each component such as the image display system, the image display device, the projection optical system, the concave reflecting surface, the screen, etc. described with reference to each drawing is merely one embodiment, and can be arbitrarily deformed without departing from the spirit of the present technology. That is, any other arbitrary configuration, algorithm, etc. for implementing the present technology may be adopted.

[0120] In the present disclosure, when the term "substantially" is used, this is only for facilitating the understanding of the description, and there is no special meaning in the use or non-use of the term "substantially". That is, in the present disclosure, concepts defining shapes, sizes, contrast relationships, positional relationships, states, etc., such as "center", "central", "uniform", "coincide", "equal", "same", "orthogonal", "parallel", "symmetric", "extend", "axial direction", "cylindrical shape", "cylindrical shape", "ring shape", "annular shape", etc. are concepts including "substantially center", "substantially central", "substantially uniform", "substantially coincide", "substantially equal", "substantially same", "substantially orthogonal", "substantially parallel", "substantially symmetric", "substantially extend", "substantially axial direction", "substantially cylindrical shape", "substantially cylindrical shape", "substantially ring shape", "substantially annular shape", etc. For example, states included in a predetermined range (for example, a range of ±10%) based on "completely center", "completely central", "completely uniform", "completely coincide", "completely equal", "completely same", "completely orthogonal", "completely parallel", "completely symmetric", "completely extend", "completely axial direction", "completely cylindrical shape", "completely cylindrical shape", "completely ring shape", "completely annular shape", etc. are also included. Therefore, even if the term "approximate" is not added, the concept expressed with the addition of the so-called "approximate" may be included. Conversely, for the state expressed with the addition of "approximate", the complete state is not excluded.

[0121] In the present disclosure, expressions using "more than", such as "greater than A" and "less than A", comprehensively include both concepts including the case of being equivalent to A and concepts not including the case of being equivalent to A. For example, "greater than A" is not limited to the case of not including equivalence to A, and also includes "equal to or greater than A". Further, "less than A" is not limited to "less than A", and also includes "less than or equal to A". When implementing the present technology, specific settings and the like may be appropriately adopted from the concepts included in "greater than A" and "less than A" so that the effects described above are exhibited.

[0122] Among the characteristic parts related to the present technology described above, it is also possible to combine at least two characteristic parts. That is, the various characteristic parts described in each embodiment may be arbitrarily combined without distinction between the embodiments. Further, the various effects described above are merely examples and are not limiting, and other effects may also be exhibited.

[0123] Note that the present technology can also adopt the following configuration. (1) A light source, An image generation unit that modulates the light emitted from the light source to generate image light, A lens system that is configured based on a reference axis at a position where the generated image light is incident and has a positive refractive power as a whole, A concave reflecting surface that is configured based on the reference axis and reflects the image light emitted from the lens system toward the object to be projected And a projection optical system having Comprising, Let the height of the light ray from the reference axis be h, Let the angle of the tangent of the function Z(h) representing the shape of the concave reflecting surface corresponding to the light ray height h with respect to the optical axis height direction be θ(h), Let the change amount of the angle θ(h) at the light ray height h be Δθ(h), assuming that the light ray height h of the reflection point farthest from the reference axis of the concave reflecting surface that reflects the image light is hmax, 0 < |Δθ(hmax) - Δθ(0.9·hmax)| / θ(hmax) < 0.056 it is configured to satisfy the relationship of an image display device. (2) The image display device according to (1), wherein the Δθ(h) is θ(h) - θ(0.98·h) an image display device. (3) The image display device according to (1) or (2), wherein, among the image light, if the light rays whose reflection points reflected by the concave reflecting surface are included in a range larger than 0.85·hmax are defined as edge-side light rays, the projection optical system is configured such that the traveling directions of the respective edge-side light rays incident on the concave reflecting surface are parallel to each other an image display device. (4) The image display device according to (3), wherein the projection optical system is configured such that the ray intervals of the edge-side light rays incident on the concave reflecting surface are equal an image display device. (5) The image display device according to any one of (1) to (4), wherein the lens system has a positive refractive power as a whole and is a first refractive optical system that refracts the generated image light, a first reflecting surface that reflects the image light refracted by the first refractive optical system, a second reflecting surface that reflects the image light reflected by the first reflecting surface, has a positive refractive power as a whole and is a second refractive optical system that refracts the image light reflected by the second reflecting surface and emits it to the concave reflecting surface and has assuming the power of the first reflecting surface is Φ1, and the power of the second reflecting surface is Φ2, then 0.1 < |Φ2 / Φ1| < 1.2 is configured to satisfy the relationship image display device. (6) The image display device according to (5), wherein |Φ2| < |Φ1| is configured to satisfy the relationship image display device. (7) The image display device according to (5) or (6), wherein when the first refractive optical system, the first reflecting surface, and the second reflecting surface are defined as a first optical system and the portion of the second refractive optical system that acts on the marginal ray is defined as a second optical system, the first optical system condenses the marginal ray at a predetermined condensing position and the predetermined condensing position coincides with the front focal position of the second optical system image display device. (8) The image display device according to (7), wherein among the marginal rays, the ray having a height at the reflection point reflected by the concave reflecting surface that is an intermediate value is defined as an intermediate ray, the incident position of the intermediate ray on the final lens surface of the second refractive optical system is defined as an intermediate incident position, the optical path length from the image generation unit to the predetermined condensing position of the intermediate ray is defined as A, the optical path length from the intermediate incident position to the front focal position is defined as B, and when the optical path length from the image generation unit to the intermediate incident position of the intermediate ray is defined as C, 0.8 < |A + B| / C < 1.2 is configured to satisfy the relationship image display device. (9) The image display device according to (8), wherein the average value of the angles at which the traveling directions of the respective marginal rays incident on the concave reflecting surface intersect the direction along the reference axis is defined as the average angle, when the region of the final lens surface of the second refractive optical system where the marginal rays are incident is defined as the marginal-side incident region, The front focal position of the second optical system is the focusing position when parallel light rays are incident from the opposite side of the edge-side incident region of the final lens surface along a direction intersecting with the direction along the reference axis at the average angle. Image display device. (10)(9) The image display device according to any one of (9). The optical path length B is the optical path length of the light ray traveling from the intermediate incident position to the rear focal position when parallel light rays are incident from the opposite side of the edge-side incident region of the final lens surface. Image display device. (11)(1) to (10) The image display device according to any one of (10). The concave reflecting surface reflects at least a part of the light rays included in the image light incident on the concave reflecting surface in a direction intersecting with the direction along the reference axis at an angle of 90 degrees or more. Image display device. (12)(1) to (11) The image display device according to any one of (11). The projection optical system has a first optical component in which a part of the main surface is configured as the first reflecting surface and a transmission surface is configured in another region of the main surface. The transmission surface of the first optical component functions as the second refractive optical system. Image display device. (13)(1) to (12) The image display device according to any one of (12). The projection optical system has a second optical component in which a part of the main surface is configured as the second reflecting surface and a transmission surface is configured in another region of the main surface. The transmission surface of the second optical component functions as the first refractive optical system. Image display device. (14)(1) to (13) The image display device according to any one of (13). The reference axis is an axis obtained by extending the optical axis of the lens closest to the image generation unit included in the lens system. Image display device. (15)(1) to (14) The image display device according to any one of (14). The projection optical system is configured such that the optical axes of all the optical components included in the projection optical system coincide with a predetermined reference axis. Image display device. (16) An image display device according to any one of (1) to (15), The concave reflecting surface is configured such that the axis of rotational symmetry coincides with the reference axis, Each of the first reflecting surface and the second reflecting surface is a concave reflecting surface and is configured such that the axis of rotational symmetry coincides with the reference axis. Image display device. (17) An image display device according to any one of (1) to (15), Each of the concave reflecting surface, the first reflecting surface, and the second reflecting surface is configured such that the optical axis coincides with the reference axis, At least one of the concave reflecting surface, the first reflecting surface, or the second reflecting surface is a free-form surface having no axis of rotational symmetry. Image display device. (18) An image display device according to any one of (1) to (17), The object to be projected is a flat screen or a curved screen. Image display device. (19) An image display system according to any one of (1) to (17), The object to be projected is a screen having a dome shape. Image display device. (20) A projection optical system that projects image light generated by modulating light emitted from a light source, A lens system that is configured with reference to a reference axis at a position where the generated image light is incident and has a positive refractive power as a whole, A concave reflecting surface that is configured with reference to the reference axis and reflects the image light emitted from the lens system toward the object to be projected and includes, Let the height of a ray from the reference axis be h, Let the angle of the tangent of the function Z(h) representing the shape of the concave reflecting surface corresponding to the ray height h with respect to the optical axis height direction be θ(h), Let the change amount of the angle θ(h) at the light ray height h be Δθ(h), assuming that the light ray height h of the reflection point farthest from the reference axis of the concave reflecting surface that reflects the image light is hmax, 0 < |Δθ(hmax) - Δθ(0.9·hmax)| / θ(hmax) < 0.056 is configured to satisfy the relationship Projection optical system.

Explanation of symbols

[0124] CE… Edge-side ray C1~C3… Pixel light F5… Final lens surface L1… First refractive optical system L2… Second refractive optical system LL1… First optical system LL2… Second optical system Mr1… First reflecting surface Mr2… Second reflecting surface Mr3… Concave reflecting surface O… Optical axis S'… Plane screen 1… Liquid crystal projector 5… Light source 10… Illumination optical system 15, 215, 315, 415… Projection optical system 20, 520, 620… Image display device 30, S… Curved screen 35… Condensing position 36… Front focal position 37… Edge-side incident region 38… Parallel rays 40… Intermediate rays 41… Intermediate incident position 100, 500, 600… Image display system

Claims

1. A light source, an image generation unit that modulates the light emitted from the light source to generate image light, a lens system configured with a reference axis as a reference at a position where the generated image light is incident, and having a positive refractive power as a whole, a concave reflecting surface configured with the reference axis as a reference and reflecting the image light emitted from the lens system toward a projection target, a projection optical system having the same, comprising: Let the height of a ray from the reference axis be h, let the angle of the tangent of the function Z(h) representing the shape of the concave reflecting surface corresponding to the ray height h with respect to the optical axis height direction be θ(h), let the change amount of the angle θ(h) at the ray height h be Δθ(h), when the ray height h of the reflection point farthest from the reference axis of the concave reflecting surface that reflects the image light is hmax, 0 < |Δθ(hmax) - Δθ(0.9·hmax)| / θ(hmax) < 0.056 is configured to satisfy the relationship of, Among the image light, when the rays whose reflection points reflected by the concave reflecting surface are included in a range larger than 0.85·hmax are defined as edge-side rays, the concave reflecting surface reflects at least a part of the edge-side rays incident on the concave reflecting surface in a direction intersecting at an angle of 90 degrees or more with the direction along the reference axis, the projection optical system is configured such that the traveling directions of the respective edge-side rays incident on the concave reflecting surface are parallel to each other and the ray intervals of the edge-side rays incident on the concave reflecting surface are equal, the lens system has a positive refractive power as a whole and is a first refractive optical system that refracts the generated image light, a first reflecting surface that reflects the image light refracted by the first refractive optical system back, a second reflecting surface that reflects the image light reflected by the first reflecting surface back, has a positive refractive power as a whole and is a second refractive optical system that refracts the image light reflected by the second reflecting surface and emits it to the concave reflecting surface, and has the same, Let the power of the first reflecting surface be Φ1, and let the power of the second reflecting surface be Φ2, 0.1 < |Φ2 / Φ1| < 1.2 and |Φ2| < |Φ1| is configured to satisfy the relationship of an image display device.

2. The image display device according to claim 1, wherein when the first refractive optical system, the first reflecting surface, and the second reflecting surface are a first optical system, and a part of the second refractive optical system that acts on the edge-side rays is a second optical system, the first optical system condenses the edge-side rays at a predetermined condensing position, The predetermined light condensing position coincides with the front focal position of the second optical system. Image display device. **Claim 3** The image display device according to claim 2, Among the edge-side light rays, a light ray having a ray height at the reflection point reflected by the concave reflecting surface being an intermediate value is defined as an intermediate ray, The incident position of the intermediate ray on the final lens surface of the second refractive optical system is defined as the intermediate incident position, The optical path length from the image generation unit of the intermediate ray to the predetermined light condensing position is A, The optical path length from the intermediate incident position to the front focal position is B, When the optical path length from the image generation unit of the intermediate ray to the intermediate incident position is C, 0.8 < |A + B| / C < 1.2 The image display device is configured to satisfy the relationship of Image display device. **Claim 4** The image display device according to claim 3, The average value of the angles at which the traveling directions of the respective edge-side light rays incident on the concave reflecting surface intersect with the direction along the reference axis is defined as the average angle, When the region of the final lens surface of the second refractive optical system where the edge-side light rays are incident is defined as the edge-side incident region, The front focal position of the second optical system is the light condensing position when parallel light rays are incident from the opposite side of the edge-side incident region of the final lens surface along the direction intersecting at the average angle with respect to the direction along the reference axis. Image display device. **Claim 5** The image display device according to claim 4, The optical path length from the intermediate incident position to the front focal position is the optical path length of the light ray traveling from the intermediate incident position to the front focal position when parallel light rays are incident from the opposite side of the edge-side incident region of the final lens surface. Image display device. **Claim 6** The image display device according to any one of claims 1 to 5, The Δθ(h) is θ(h) - θ(0.98·h). Image display device. **Claim 7** The image display device according to any one of claims 1 to 6, The projection optical system has a first optical component in which a part of the principal surface is configured as the first reflecting surface and a transmission surface is configured in another region of the principal surface, The transmission surface of the first optical component functions as the second refractive optical system. Image display device. **Claim 8** The image display device according to any one of claims 1 to 7, The projection optical system has a second optical component in which a part of the principal surface is configured as the second reflecting surface and a transmission surface is configured in another region of the principal surface, The transmission surface of the second optical component functions as the first refractive optical system. Image display device.

9. The image display device according to any one of claims 1 to 8, wherein the reference axis is an axis obtained by extending the optical axis of the lens closest to the image generation unit included in the lens system. Image display device.

10. The image display device according to any one of claims 1 to 9, wherein the projection optical system is configured such that the optical axes of all the optical components included in the projection optical system coincide with a predetermined reference axis. Image display device.

11. The image display device according to any one of claims 1 to 10, wherein the concave reflecting surface is configured such that the axis of rotational symmetry coincides with the reference axis, and each of the first reflecting surface and the second reflecting surface is a concave reflecting surface and is configured such that the axis of rotational symmetry coincides with the reference axis. Image display device.

12. The image display device according to any one of claims 1 to 10, wherein each of the concave reflecting surface, the first reflecting surface, and the second reflecting surface is configured such that the optical axis coincides with the reference axis, and at least one of the concave reflecting surface, the first reflecting surface, or the second reflecting surface is a free-form surface having no axis of rotational symmetry. Image display device.

13. The image display device according to any one of claims 1 to 12, wherein the object to be projected is a flat screen or a curved screen. Image display device.

14. The image display system according to any one of claims 1 to 12, wherein the object to be projected is a screen having a dome shape. Image display device.

15. A projection optical system that projects image light generated by modulating light emitted from a light source, comprising a lens system configured based on a reference axis at a position where the generated image light is incident and having a positive refractive power as a whole, and a concave reflecting surface configured based on the reference axis and reflecting the image light emitted from the lens system toward the object to be projected. The projection optical system comprises: Let the height of a ray from the reference axis be h, let the angle of the tangent of the function Z(h) representing the shape of the concave reflecting surface corresponding to the ray height h with respect to the optical axis height direction be θ(h), let the change amount of the angle θ(h) at the ray height h be Δθ(h), and when the ray height h of the reflection point farthest from the reference axis of the concave reflecting surface that reflects the image light is hmax, it is configured to satisfy the relationship of 0 < |Δθ(hmax) - Δθ(0.9·hmax)| / θ(hmax) < 0.

056. ​ Among the image light, when the light rays whose reflection points reflected by the concave reflecting surface are included in a range larger than 0.85·hmax are defined as edge-side light rays, the concave reflecting surface reflects at least a part of the edge-side light rays incident on the concave reflecting surface in a direction intersecting at an angle of 90 degrees or more with the direction along the reference axis, the projection optical system is configured such that the traveling directions of the respective edge-side light rays incident on the concave reflecting surface are parallel to each other and the ray intervals of the edge-side light rays incident on the concave reflecting surface are equal, the lens system has a first refractive optical system having a positive refractive power as a whole and refracting the generated image light, a first reflecting surface that reflects the image light refracted by the first refractive optical system by folding it back, a second reflecting surface that reflects the image light reflected by the first reflecting surface by folding it back, and a second refractive optical system having a positive refractive power as a whole and refracting the image light reflected by the second reflecting surface and emitting it to the concave reflecting surface and has when the power of the first reflecting surface is Φ1, and the power of the second reflecting surface is Φ2, it is configured to satisfy the relationship of 0.1 < |Φ2 / Φ1| < 1.2 and |Φ2| < |Φ1| Projection optical system. ​

Images