Screen, image projection system, and vehicle

Abstract

A screen according to one embodiment of the present technology displays an image in response to projection of image light having, as a main component, light in a prescribed polarized state, the screen having an uneven surface and an optical element. The uneven surface includes a plurality of reflective surfaces that have light transmissivity and that diffuse and reflect the projected image light. The optical element is configured, in accordance with the polarization state of the image light, on a second side of the uneven surface opposite to a first side on which the image light is projected, and the optical element restricts the transmission of the image light to the second side, and transmits at least a portion of the light entering from the second side.

Description

[Technical Field]

[0001] The present technology relates to a screen, an image projection system, and a vehicle. [Background technology]

[0002] Patent Document 1 describes a projection observation device that is attached to the dashboard of an automobile and simultaneously displays different images to both the driver and the passenger in the front passenger seat, for example, a navigation image to the driver and a TV image to the passenger, allowing them to view them separately (see, for example, Figure 39 in paragraph

[0159] of the specification of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-102204 Summary of the Invention [Problem to be solved by the invention]

[0004] In cases where images are viewed in vehicles or the like, there is a demand for technology that can provide a good viewing environment for viewers.

[0005] In view of the above circumstances, an object of the present technology is to provide a screen, an image projection system, and a vehicle that can realize a good viewing environment. [Means for solving the problem]

[0006] In order to achieve the above object, a screen according to one embodiment of the present technology is a screen that displays an image in response to irradiation with image light whose main component is light in a predetermined polarization state, and has an uneven surface and an optical element portion. The uneven surface includes a plurality of reflective surfaces that are optically transparent and that diffusely reflect the irradiated image light. The optical element portion is configured to correspond to the polarization state of the image light on a second side opposite to the first side of the uneven surface onto which the image light is irradiated, and restricts transmission of the image light to the second side and transmits at least a portion of the light incident from the second side.

[0007] In this screen, image light is diffused and reflected by multiple reflective surfaces included in the uneven surface. This makes it possible to display an image to a viewer on the first side. Furthermore, the optical element section restricts transmission of image light to the second side, and transmits a portion of light incident from the second side. This makes it possible to use this screen as a transparent screen. It also makes it possible to suppress leakage of image light to the second side. As a result, a good viewing environment is realized for the viewer.

[0008] The screen may display the image in response to irradiation with the image light whose main component is linearly polarized light, circularly polarized light, or elliptically polarized light.

[0009] The optical element section may include a polarizing plate whose light-shielding axis is oriented in a predetermined direction.

[0010] The direction of the light blocking axis of the polarizing plate may be defined with reference to the vertical direction.

[0011] If a plane containing the normal and the vertical direction at a predetermined reference point within the screen is defined as a reference plane, the direction of the shading axis of the polarizing plate may be set to a direction that is perpendicular to the normal and parallel to the reference plane.

[0012] The screen may display the image in response to irradiation with the image light whose main component is linearly polarized light whose vibration plane is the reference plane.

[0013] If the polarizing plate is a first polarizing plate, the optical element section may include a quarter-wave plate that is arranged on the second side of the first polarizing plate and converts linearly polarized light, the polarization direction of which is the direction of the shading axis of the first polarizing plate, into circularly polarized light, and a second polarizing plate that is arranged on the second side of the quarter-wave plate and has a shading axis direction that is perpendicular to the shading axis direction of the first polarizing plate.

[0014] The optical element section may include a half-wave plate arranged on the second side of the polarizing plate and configured to convert linearly polarized light having a polarization direction in the direction of the shading axis of the polarizing plate into linearly polarized light having a polarization direction perpendicular to the direction of the shading axis of the polarizing plate.

[0015] The screen may display the image in response to irradiation with the image light whose main component is elliptically polarized light whose major axis is parallel to the reference plane.

[0016] The screen may display the image in response to irradiation with the image light mainly composed of circularly polarized light. In this case, the optical element unit may include a quarter-wave plate disposed on the first side of the polarizing plate and configured to convert the circularly polarized light into linearly polarized light having a polarization direction aligned with the light-blocking axis of the polarizing plate.

[0017] The screen may display the image in response to irradiation with the image light mainly composed of elliptically polarized light. In this case, the optical element unit may include a retardation plate disposed on the first side of the polarizing plate and configured to convert the elliptically polarized light into linearly polarized light having a polarization direction aligned with the light-blocking axis of the polarizing plate.

[0018] When a plane including a normal to a predetermined reference point within the screen and a vertical direction is defined as a reference plane, the direction of the light-blocking axis of the polarizing plate may be set to be parallel to the normal to the reference plane.

[0019] The predetermined reference point within the screen may be a point at which the screen intersects with the optical axis of the image light.

[0020] The plurality of reflecting surfaces may be made of a light-transmitting material and configured as rough surfaces.

[0021] The plurality of reflecting surfaces may be configured by disposing a light diffusing material on a surface made of a light-transmitting material.

[0022] When a plane including a normal to a predetermined reference point within the screen and the vertical direction is defined as a reference plane, each of the plurality of reflecting surfaces may be a plane that is not perpendicular to the reference plane.

[0023] If a plane containing the normal and the vertical direction at a predetermined reference point within the screen is taken as a reference plane, each of the multiple reflecting surfaces may be a curved surface, and may be configured so that the tangent plane at the part where it intersects with the reference plane is not perpendicular to the reference plane.

[0024] An image projection system according to an embodiment of the present technology includes an image projection device that irradiates image light that is mainly composed of light in a predetermined polarization state, and the screen.

[0025] A vehicle according to an embodiment of the present technology includes an image projection device that irradiates image light that is mainly composed of light in a predetermined polarization state, and the screen.

[0026] The vehicle may further include a window, in which case the screen may be configured in at least a partial area of ​​the window. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a schematic diagram showing a basic configuration of an image projection system according to an embodiment of the present technology. [Figure 2] FIG. 1 is a schematic diagram showing an example of the arrangement of short focus projectors. [Figure 3] FIG. 1 is a schematic diagram illustrating an example of the configuration of an optical system in a short focus projector. [Figure 4] FIG. 4 is an enlarged schematic view showing a part of the optical system shown in FIG. 3. [Figure 5] FIG. 10 is a schematic diagram showing another example of the configuration of an optical system in a short focus projector. [Figure 6] FIG. 2 is a schematic diagram showing an example of the configuration of an uneven surface. [Figure 7] FIG. 2 is a schematic diagram illustrating a configuration example of an optical element section. [Figure 8] FIG. 2 is a schematic diagram illustrating a configuration example of an optical element section. [Figure 9] FIG. 2 is a schematic diagram illustrating a configuration example of an optical element section. [Figure 10] FIG. 2 is a schematic diagram illustrating a configuration example of an optical element section. [Figure 11] FIG. 2 is a schematic diagram illustrating an example of a method for setting the direction of the absorption axis of a polarizing plate. [Figure 12] FIG. 10 is a schematic diagram showing an example of setting an image display direction (direction). [Figure 13] 1A and 1B are schematic diagrams showing specific configuration examples of the uneven surface. [Figure 14] 1A and 1B are schematic diagrams showing specific configuration examples of the uneven surface. [Figure 15] 1A and 1B are schematic diagrams showing specific configuration examples of the uneven surface. [Figure 16] FIG. 10 is a schematic diagram for explaining a tangent plane. [Figure 17] 2 is a cross-sectional view of the screen cut along a reference plane S. FIG. [Figure 18] FIG. 10 is a schematic diagram showing another example of the configuration of the uneven surface. [Figure 19] FIG. 2 is a schematic diagram illustrating an example of a Fresnel lens shape. [Figure 20] FIG. 1 is a schematic diagram illustrating an example of an image projection system installed in a vehicle. [Figure 21] FIG. 1 is a schematic diagram illustrating an example of an image projection system installed in a vehicle. [Figure 22] FIG. 22 is a schematic diagram showing an image projection system in the vehicle shown in FIGS. 20 and 21. [Figure 23] FIG. 10 is a schematic diagram showing another example of an image projection system mounted in a vehicle. [Figure 24] FIG. 10 is a schematic diagram showing another example of an image projection system mounted in a vehicle. DETAILED DESCRIPTION OF THE INVENTION

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

[0029] [Basic configuration of image projection system] FIG. 1 is a schematic diagram showing a basic configuration of an image projection system according to an embodiment of the present technology. In this disclosure, an image includes both a still image and a moving image (video). An image projection system may also be referred to as a video projection system.

[0030] The image projection system 1 includes an image projection device 2 and a screen 3 . The image projection device 2 projects image light L1 that constitutes an image. In this embodiment, the image light L1 is irradiated, the main component of which is light in a predetermined polarization state. For example, when observing the distribution of polarization states of light contained in the image light L1, the light in the most abundant polarization state can be said to be the main component. 1, image light L1 mainly composed of, for example, linearly polarized light, circularly polarized light, or elliptically polarized light is irradiated toward a screen 3. Alternatively, image light L1 mainly composed of linearly polarized light with a predetermined plane as the vibration plane, or image light L1 mainly composed of linearly polarized light with a predetermined direction as the polarization direction (vibration direction), etc. may be irradiated. In addition, the present technology can be applied to image light L1 mainly composed of light in any polarization state other than unpolarized light.

[0031] For example, the image projection device 2 can be a projector that forms an optical image (image light L1) according to a video signal by spatially modulating light emitted from a light source. As shown in FIG. 1, in this embodiment, a short focus projector is used as the image projection device 2 (hereinafter, referred to as the short focus projector 2 using the same reference numeral). The short focus projector 2 is a projector that supports an ultra-wide angle, for example, with a half angle of view of 70° or more, and is also called an ultra-wide angle projector or an ultra-short focus projector. By using the short focus projector 2, it is possible to display a large screen even in a small projection space. In other words, enlarged projection is possible even when the distance between the short focus projector 2 and the screen 3 is short. This allows for a high degree of freedom in selecting the installation location, and the projector can be easily installed in a narrow installation space or on a ceiling with many obstacles. Of course, a device other than a short focus projector may be used as the image projection device 2.

[0032] The screen 3 displays an image by irradiating the image light L1 from the short focus projector 2. In this embodiment, the screen 3 is designed in accordance with the polarization state of the image light L1. 1, the screen 3 displays an image on the side where the image light L1 is irradiated by the short focus projector 2. That is, the screen 3 diffuses and reflects the light from the short focus projector 2 in the direction where the short focus projector 2 is placed. The screen 3 is optically transparent and can be used as a so-called transparent screen. In the present disclosure, the term "transparent" includes not only completely transparent but also semi-transparent and colored transparent. In the following description, the side of the screen 3 onto which the image light L1 is irradiated, i.e., the side on which the image is displayed, is referred to as the front side, and the opposite side is referred to as the rear side. The front side corresponds to an embodiment of the first side according to the present technology, and the rear side corresponds to an embodiment of the second side according to the present technology.

[0033] As shown in FIG. 1, the screen 3 includes a screen portion 4 and an optical element portion 5. The screen portion 4 and the optical element portion 5 are made of a plastic material. The screen unit 4 has a function of displaying an image to a user (viewer). The screen unit 4 has a screen surface 6, an uneven surface 7, and a rear surface 8. The screen surface 6 is the outermost surface on the front side (display side), and is typically configured in a flat shape facing the front of the screen 3.

[0034] In this embodiment, the uneven surface 7 is configured inside the screen unit 4. The uneven surface 7 realizes a fine directivity angle control structure that can direct the image light L1 of the short focus projector 2 in a specific direction. Note that the uneven surface 7 may also be configured as the outermost surface. 1, the uneven surface 7 has a plurality of reflecting surfaces 9 and a plurality of connecting surfaces 10. The reflecting surfaces 9 and the connecting surfaces 10 are arranged alternately, and adjacent reflecting surfaces 9 and connecting surfaces 10 form recesses and protrusions, respectively.

[0035] The plurality of reflective surfaces 9 are optically transparent and diffusely reflect the irradiated image light L1, so that the viewer views the image light L1 diffused and reflected by each of the plurality of reflective surfaces 9 as an image. Each of the plurality of reflecting surfaces 9 is configured to be oriented in a predetermined image display direction. The predetermined image display direction is the direction in which an image is desired to be displayed to the viewer, and can also be said to be the direction in which the image light L1 is directed.

[0036] In this embodiment, the orientation, shape, etc. of each of the multiple reflecting surfaces 9 are appropriately designed with a direction different from the front direction of the screen 3 as the image display direction. Therefore, the orientation of the screen surface 6 and the orientation of each of the multiple reflecting surfaces 9 are designed to be different. The plurality of reflective surfaces 9 may be formed so as to face in the same direction as one another. However, the present invention is not limited to this, and the reflective surfaces 9 may be configured so as to face in different directions from one another so as to display an image in a desired direction. Furthermore, the shape of each of the plurality of reflecting surfaces 9 is not limited, and a flat surface, a curved surface, etc. may be appropriately adopted. Each of the plurality of reflecting surfaces 9 may be configured to have the same shape, or each reflecting surface 9 may have a different shape. The width and pitch of the plurality of reflecting surfaces 9 are designed to be on the order of μm, for example, but of course, are not limited to such size design.

[0037] Each of the plurality of connecting surfaces 10 connects adjacent reflecting surfaces 9 together. 1, the connecting surface 10 is configured to be approximately parallel to the depth direction of the screen 3 when viewed from the front side. Then, a plurality of reflecting surfaces 9, each having approximately the same shape when viewed from the front side, are configured to be aligned in the vertical direction. Therefore, when the screen 3 is viewed from the side, the uneven surface 7 is configured in a sawtooth shape. Of course, this is not limitative, and the orientation and shape of the multiple connecting surfaces 10 may be designed arbitrarily.

[0038] The rear surface 8 is the outermost surface on the rear side, and is typically configured to have a flat shape so as to be parallel to the screen surface 6.

[0039] The optical element section 5 is configured on the rear side opposite to the side (i.e., the front side) onto which the image light L1 is irradiated of the uneven surface 7. That is, the optical element section 5 is connected to the rear surface 8 of the screen section 4. The optical element unit 5 is configured to correspond to the polarization state of the image light L1 and restricts transmission of the image light L1 to the rear side. The optical element unit 5 also transmits at least a portion of the background light L2 incident from the rear side. This makes it possible to prevent image light L1 from leaking behind the screen 3. It also makes it possible for viewers to see the background of the screen 3, making it possible to use the screen 3 as a transparent screen.

[0040] In this embodiment, the vertical direction is defined as the Y direction, and the screen 3 is disposed so that the planar direction of the screen surface 6 is parallel to the Y direction (vertical direction). The normal direction of the screen surface 6 is defined as the Z direction, and the direction perpendicular to both the Y direction and the Z direction is defined as the X direction. Therefore, the Z direction is the front direction of the screen 3, and the X direction is the horizontal direction. Furthermore, in the X direction (horizontal direction), Y direction (vertical direction), and Z direction (perpendicular direction), descriptions such as above, below, left side, right side, front side, and back side may be used relative to the viewer. In the example shown in Figure 1, the side where the X arrow points is the right side, and the opposite side is the left side. The side where the Y arrow points is the top side, and the opposite side is the bottom side. The side where the Z arrow points is the front side, and the opposite side is the back side. Of course, the application of this technology is not limited to such directional definitions.

[0041] [Example of short-focus projector placement] FIG. 2 is a schematic diagram showing an example of the arrangement of the short focus projector 2. As shown in FIG. 2A, the short focus projector 2 may be disposed at a position shifted upward in the Y direction (vertical direction) with respect to the screen 3. Then, the image light L1 may be emitted obliquely downward from the upper side in the Y direction. 2B, the short focus projector 2 may be disposed at a position shifted upward in the Y direction (vertical direction) and to the left in the X direction (horizontal direction) with respect to the screen 3. Then, the image light L1 may be emitted obliquely downward from the upper side in the Y direction and from the left side to the right side in the X direction. Of course, the arrangement is not limited to this, and various arrangements may be adopted. For example, a short focus projector 2 with a throw ratio of 0.35 or less is used, which makes it possible to easily configure the image projection system 1 even in a narrow space such as the interior space of a vehicle. Since the short-focus projector 2 can be placed on the ceiling or the like inside the vehicle, it is possible to project the image light L1 onto the screen 3 while avoiding the heads and bodies of the viewers (vehicle passengers), thereby realizing a good viewing environment.

[0042] FIG. 3 is a schematic diagram showing an example of the configuration of an optical system in the short focus projector 2. As shown in FIG. FIG. 4 is an enlarged schematic view of a part of the optical system shown in FIG. 3 and 4 show configuration examples in which image light L1 is emitted that is mainly composed of linearly polarized light whose vibration plane is a plane parallel to the YZ plane.

[0043] The short focus projector 2 includes a light source unit 12, a collimator lens 13, a fly's eye lens 14, a polarization conversion element 15, condenser lenses 16a and 16b, and a reflecting mirror 17. The short focus projector 2 also has a polarizing beam splitter (PBS) 18, a reflective light modulation element 19, a group of projection lenses 20, and a reflecting mirror 21.

[0044] The light source unit 12 generates white light and includes, for example, a solid-state light source such as an LED (Light Emitting Diode) or an LD (Laser Diode), or a mercury lamp or a xenon lamp. For example, RGB solid-state light sources capable of emitting light of each color may be used, and these emitted lights may be combined to generate white light W. Alternatively, a solid-state light source that emits light in the blue wavelength band may be provided, and a phosphor that is excited by the blue light and emits yellow fluorescence may be provided. In this case, the blue light and yellow light are combined to emit white light. The white light emitted from the light source unit 12 is collimated by the collimator lens 13, and the brightness is made uniform by the fly-eye lens . The polarization conversion element 15 has a function of aligning the polarization state of incident white light. In this embodiment, the white light is converted into light mainly composed of linearly polarized light whose vibration plane is parallel to the XZ plane. Any optical element such as a PS converter may be used as the polarization conversion element 15. 3 and 4, light whose main component is linearly polarized light whose vibration plane is parallel to the XZ plane is simply referred to as X-polarized light, and light whose main component is linearly polarized light whose vibration plane is parallel to the YZ plane is simply referred to as Y-polarized light.

[0045] The white light, which is mainly composed of linearly polarized light with its vibration plane parallel to the XZ plane, passes through condenser lens 16a and strikes reflecting mirror 17, where it is reflected downward in the Y direction. The reflected white light then strikes PBS 18.

[0046] The PBS 18 reflects the linearly polarized component of the white light polarized in the X direction and transmits the linearly polarized component polarized in the Y direction. The PBS 18 is positioned so that the separation of the polarized light occurs in a plane parallel to the YZ plane. As shown in Figure 4, white light (X-polarized light) that is mainly composed of linearly polarized light with its vibration plane parallel to the XY plane and that enters PBS18 from above in the vertical direction is reflected toward the back in the Z direction (left side in the figure) and enters reflective light modulation element 19.

[0047] The reflective light modulation element 19 modulates and reflects incident white light based on an image signal supplied from the outside. The modulated white light is emitted as image light L1 that constitutes a color image. A reflective liquid crystal panel is typically used as the reflective light modulation element 19, but is not limited to this. Any microdisplay device such as a digital micromirror device (DMD) may also be used. Note that any method may be adopted as a method for generating a color image from white light using one reflective light modulation element 19. For example, a color wheel or the like is used to time-divide white light into RGB color lights. Then, image light of each RGB color is generated and irradiated based on an image signal for each color. Alternatively, the white light may be emitted continuously without time-dividing, and a reflective light modulation element 19 may be used in which one pixel is composed of three RGB color sub-pixels. Alternatively, a so-called color sequential method may be used in which solid-state light sources such as LEDs or LDs for each of the RGB colors are illuminated in time sequence, and image light for each of the RGB colors is formed based on an image signal for each color. As another configuration example, a method of generating a color image using multiple reflective light modulation elements 19 can be adopted. For example, a hybrid method may be used in which two reflective liquid crystal modulation elements 19 are arranged via one PBS 18 to separate colors by polarization, and a color sequential method using a time-division fluorescent wheel or the like is combined. In this case, the white light may be a combination of yellow light fluoresced by a phosphor and blue light for excitation, which are emitted in time sequence. Any other method using multiple reflective light modulation elements 19 may be adopted.

[0048] 4, image light L1 (Y-polarized light) mainly composed of linearly polarized light whose vibration plane is parallel to the YZ plane is emitted from reflective light modulation element 19. Image light L1 passes through PBS 18 and enters reflection mirror 21 via projection lens group 20. The image light L1, which is mainly composed of linearly polarized light whose vibration plane is parallel to the YZ plane, is reflected by the reflecting mirror 21, and the image light L1 is irradiated towards the screen 3. 4 shows a reflecting mirror 21 with a flat reflecting surface, but typically an aspherical mirror with an aspherical reflecting surface is used, although of course the present invention is not limited to such a configuration.

[0049] 3 and 4, it is possible to realize a small short-focus projector 2 with a small thickness (size in the Y direction). As a result, it is very advantageous in configuring the image projection system 1 in a narrow space such as the interior space of a vehicle. Of course, the configuration of the optical system in the short focus projector 2, the method of generating an image, etc. are not limited and may be set arbitrarily.

[0050] FIG. 5 is a schematic diagram showing another example of the configuration of the optical system in the short focus projector 2. In FIG. FIG. 5 shows an example of a configuration in which image light L1 containing circularly polarized light or elliptically polarized light as a main component is emitted. 5, a retardation plate 22 is disposed as an additional optical element. The retardation plate 22 is disposed after the reflecting mirror 21, at the exit port for the image light L1. For example, a quarter-wave plate (QWP) is disposed as the retardation plate 22 so that its optical axis intersects the YZ plane at an angle of 45 degrees, thereby making it possible to irradiate image light L1 that is mainly composed of circularly polarized light. In addition, the quarter-wave plate is arranged so that its optical axis intersects with the YZ plane at an angle other than 45 degrees, which makes it possible to irradiate image light L1 that is mainly composed of elliptically polarized light. Of course, the retardation plate 22 is not limited to the quarter wave plate (QWP), and any retardation plate having a predetermined phase difference can be used as appropriate. For example, by arranging a retarder 22 having a predetermined phase difference at a predetermined azimuth angle, it becomes possible to irradiate image light L1 whose main component is circularly polarized light. Similarly, by arranging a retarder 22 having a predetermined phase difference at a different predetermined azimuth angle, it becomes possible to irradiate image light L1 whose main component is elliptically polarized light. For example, it is possible to adjust the direction of the major axis of the elliptically polarized light and the ellipticity by appropriately adjusting the direction (azimuth angle) of the optical axis of the retardation plate 22. For example, it is also possible to irradiate image light L1 mainly composed of elliptically polarized light whose major axis direction is parallel to the YZ plane. Note that the direction of the major axis of the elliptically polarized light can be determined by the ellipse azimuth angle. The retarder 22 may be disposed at any position after the PBS 18. For example, the retarder 22 may be disposed at any position, such as between the PBS 18 and the projection lens group 20, inside the projection lens group 20, or between the projection lens group 20 and the reflecting mirror 21.

[0051] [Example of uneven surface configuration] FIG. 6 is a schematic diagram showing an example of the configuration of the uneven surface 7. As shown in FIG. In the example shown in FIG. 6A, the multiple reflective surfaces 9 are made of a light-transmitting material and are configured as rough surfaces. This makes it possible to diffuse and reflect the image light L1. The structure for diffusing the image light L1 can also be called a diffusing structure or a scattering structure. In the example shown in FIG. 6A, a diffusing structure (scattering structure) is realized by forming a rough surface using a light-transmitting material.

[0052] An example of a method for manufacturing the uneven surface 7 shown in FIG. 6A will be described. A mold having the shape of the uneven surface 7 is created by cutting or the like. At this time, the mold is created so that the surfaces corresponding to the reflecting surface 9 and the connecting surface 10 have a flat shape. In this embodiment, a sawtooth mold is cut. A rough surface is formed on the mold by corrosion treatment or the like. The microstructure (convex and concave surface) of the mold is transferred to a transparent body having optical transparency. For example, heat pressing, injection molding, UV molding, etc. may be used. Furthermore, for the transparent body, for example, thermoplastic resin, UV curable resin, electron beam curable resin, etc. may be used. Of course, the method and materials are not limited to these. A half mirror film, such as a metal film made of chromium or aluminum, or a dielectric multilayer film, is formed on the transparent body onto which the textured surface has been transferred. Another transparent body is connected to the transparent body so as to fill the uneven surface 7.

[0053] Another example of a method for manufacturing the uneven surface 7 shown in FIG. 6A will be described. A mold having the shape of the uneven surface 7 is created by cutting or the like. At this time, the mold is created so that the surfaces corresponding to the reflecting surface 9 and the connecting surface 10 have a flat shape. In this embodiment, a sawtooth mold is cut. The microstructure of the mold (the uneven surface consisting of a flat shape) is transferred to a transparent body that has optical transparency. The uneven surface of the transparent body is roughened by sandblasting or the like. A half mirror film, such as a metal film made of chromium or aluminum, or a dielectric multilayer film, is formed on the transparent body onto which the textured surface has been transferred. Another transparent body is connected to the transparent body so as to fill the uneven surface 7.

[0054] 6B, the multiple reflective surfaces 9 are configured by disposing a light diffusing material 25 on surfaces 24 made of a light-transmitting material. A diffusing structure (scattering structure) is realized, which makes it possible to diffuse and reflect the image light L1. Examples of the light diffusing material 25 that can be used include inorganic light diffusing materials such as silica, muscovite, alumina, calcium carbonate, and glass beads, and amorphous organic light diffusing materials such as acrylic resins, styrene resins, and copolymers thereof, and silicone resins. Any other light diffusing material may also be used. Furthermore, there are no limitations on the distribution of the light diffusion material on the reflecting surface 9, and it may be set arbitrarily. For example, the light diffusion material 25 may be sparsely arranged on the surface 24.

[0055] An example of a method for manufacturing the uneven surface 7 shown in FIG. 6B will be described. A mold having the shape of the uneven surface 7 is made by cutting or the like. The mold is made so that the surfaces corresponding to the reflecting surface 9 and the connecting surface 10 have flat shapes. In this embodiment, a sawtooth mold is cut. The microstructure of the mold (the uneven surface consisting of a flat shape) is transferred to a transparent body that has optical transparency. A half mirror film, such as a metal film made of chromium or aluminum, or a dielectric multilayer film, is formed on the transparent body onto which the textured surface has been transferred. A light diffusing material is dispersed on the uneven surface, or a dispersion of the light diffusing material is applied to the uneven surface and then dried. Another transparent body is connected to the transparent body so as to fill the uneven surface 7.

[0056] [Example of optical element configuration] 7 to 10 are schematic diagrams showing configuration examples of the optical element section 5. FIG. In this embodiment, a polarizing plate (linear polarizing plate) 27 whose light-shielding axis is oriented in a predetermined direction is used. When an absorption type polarizing plate is used as the polarizing plate 27, the absorption axis becomes the light blocking axis. Of the image light L1 that is not reflected by the multiple reflecting surfaces 9 and passes through the uneven surface 7, the linearly polarized component whose vibration plane is a plane including the direction of the absorption axis of the polarizing plate 27 is absorbed by the polarizing plate 27. On the other hand, of the background light L2, the linearly polarized component whose vibration plane is a plane including the direction of the transmission axis of the polarizing plate 27 is transmitted forward through the screen unit 4. The directions of the absorption axis and the transmission axis of the polarizing plate 27 are orthogonal to each other.

[0057] When a reflective polarizing plate is used as the polarizing plate 27, the reflective axis becomes the light blocking axis. Of the image light L1 that is not reflected by the multiple reflecting surfaces 9 and passes through the uneven surface 7, the linearly polarized component whose vibration plane is a plane including the direction of the reflection axis of the polarizing plate 27 is reflected by the polarizing plate 27. On the other hand, the linearly polarized component of the background light L2, whose vibration plane is a plane including the direction of the transmission axis of the polarizing plate 27, passes through the screen unit 4 and is transmitted forward. The directions of the reflection axis and the transmission axis of the polarizing plate 27 are orthogonal to each other.

[0058] Whether an absorptive polarizing plate or a reflective polarizing plate is used as the polarizing plate 27, it is possible to restrict transmission of image light L1 to the rear side and also to transmit at least a part of background light L2 incident from the rear side. As the polarizer 27, any polarizer may be used, such as an iodine-based polarizer, a dichroic polarizer using dyes, or a wire grid polarizer.

[0059] For example, the image light L1 is irradiated with light that is mainly composed of linearly polarized light whose vibration plane is a plane that includes the direction of the light-blocking axis of the polarizing plate 27. This makes it possible to almost completely block the image light L1 that passes through the screen unit 4. Of course, the restriction of transmission of the image light L1 to the rear side can also be achieved for image light L1 whose main component is circularly polarized light or elliptically polarized light. For example, when elliptically polarized light is used as the image light L1, the image light L1 is made to be mainly composed of elliptically polarized light whose major axis direction is parallel to the plane including the direction of the light-blocking axis of the polarizing plate 27. This makes it possible to enhance the effect of restricting transmission of the image light L1 to the rear side. Note that controlling the polarization state of the image light L1 in accordance with the direction of the light-shielding axis of the polarizing plate 27 can also be said to be setting the direction of the light-shielding axis of the polarizing plate 27 in accordance with the polarization state of the image light L1. That is, in application of the present technology, the polarization state of the image light L1 may be controlled in accordance with the configuration of the optical element unit 5 (such as the direction of the light-shielding axis of the polarizing plate 27). Furthermore, the configuration of the optical element unit 5 (such as the direction of the light-shielding axis of the polarizing plate 27) may be set as appropriate in accordance with the polarization state of the image light L1.

[0060] The following description will be given taking as an example a case where an absorption-type polarizing plate is used as the polarizing plate 27. That is, the description will be given taking as an example a case where the light-shielding axis is the absorption axis. Furthermore, when a polarizing plate different from the polarizing plate 27 (for example, the second polarizing plate 29 shown in FIG. 8) is used, it is also considered to be an absorptive polarizing plate. Of course, a reflective polarizing plate can also be used as appropriate.

[0061] 7, the direction of the absorption axis of the polarizing plate 27 is defined based on the Y direction (vertical direction). Specifically, the polarizing plate 27 is disposed so that the direction of the absorption axis is the Y direction (vertical direction). As the image light L1, light containing linearly polarized light as a main component, with the vibration plane being parallel to the YZ plane, is irradiated. As shown in FIG. 7B, the image light L1 transmitted through the screen unit 4 is absorbed by the polarizing plate 27. 7A and 7B, the polarization direction of linearly polarized light having a vibration plane parallel to the YZ plane may differ depending on the incident angle (incident position) of the image light L1 incident on the screen 3. Specifically, the inclination toward the screen 3 changes depending on the incident angle of the image light L1. This can also be said to result in different linearly polarized components in the Z direction depending on the incident angle of the image light L1. Even with respect to such linearly polarized light, the polarizing plate 27, whose absorption axis is oriented in the Y direction, can sufficiently absorb it. That is, the absorption effect of the polarizing plate 27 is sufficiently exhibited regardless of the inclination of the linearly polarized light in a plane parallel to the YZ plane. Furthermore, the image light L1 incident on the left and right ends of the image may have a linearly polarized component in the X direction. It is difficult for the polarizing plate 27 to absorb the linearly polarized component in the X direction. However, the linearly polarized component in the X direction is very small compared to the whole, so it is possible to block almost the entire image light L1, thereby achieving a high effect.

[0062] 7B, of background light L2 incident on optical element unit 5 from the rear side, the linearly polarized component (Y-polarized light) whose vibration plane is parallel to the YZ plane is absorbed by polarizing plate 27. Of background light L2, the linearly polarized component (X-polarized light) whose vibration plane is parallel to the XZ plane is transmitted through polarizing plate 27 and screen unit 4, and is emitted forward.

[0063] In the optical element section 5 shown in FIG. 8, in addition to the polarizing plate 27, a quarter-wave plate 28 and another polarizing plate 29 are arranged. The polarizing plate 27 will be referred to as a first polarizing plate 27 using the same reference numeral, and the polarizing plate 29 will be referred to as a second polarizing plate 29 using the same reference numeral. The quarter-wave plate 28 is disposed on the rear side of the first polarizing plate 27. The quarter-wave plate 28 converts linearly polarized light, the polarization direction of which is the absorption axis direction of the first polarizing plate 27, i.e., the Y direction, into circularly polarized light. Therefore, the quarter-wave plate 28 is disposed so that its optical axis intersects with the Y direction at an angle of 45 degrees. The second polarizing plate 29 is disposed on the rear side of the quarter-wave plate 28. The second polarizing plate 29 is disposed so that the direction of its absorption axis is perpendicular to the direction of the absorption axis of the first polarizing plate 27. In other words, the second polarizing plate 29 is disposed so that the direction of its absorption axis is the X direction.

[0064] As shown in FIG. 8B, the image light L1 transmitted through the screen unit 4 is absorbed by the first polarizing plate 27. Of the background light L2 incident on the optical element unit 5 from the rear side, the linearly polarized light component (Y-polarized light) whose vibration plane is parallel to the YZ plane passes through the second polarizing plate 29 and enters the quarter-wave plate 28. It is then converted into circularly polarized light by the quarter-wave plate 28. Of the circularly polarized light, the X-polarized light component whose vibration plane is parallel to the XZ plane passes through the first polarizing plate 27 and the screen unit 4 and is emitted forward. Of the background light L2, the linearly polarized light component (X-polarized light) whose vibration plane is parallel to the XZ plane is absorbed by the second polarizer 29.

[0065] In the optical element section 5 shown in FIG. 9, in addition to the polarizing plate 27, a half-wave plate (HWP) 30 is arranged. The half-wave plate 30 is disposed on the rear side of the polarizing plate 27. The half-wave plate 30 converts linearly polarized light polarized in the direction of the absorption axis of the polarizing plate 27, i.e., the Y direction, into linearly polarized light polarized in the direction perpendicular to the direction of the absorption axis of the polarizing plate 27, i.e., the X direction. That is, the half-wave plate 30 rotates the polarization direction of linearly polarized light whose polarization direction is the Y direction by 90 degrees. Therefore, the half-wave plate 30 is disposed so that its optical axis intersects with the Y direction at an angle of 45 degrees.

[0066] As shown in FIG. 9B, the image light L1 transmitted through the screen unit 4 is absorbed by the polarizing plate 27. Of the background light L2 incident on the optical element unit 5 from the rear side, the linearly polarized light component (Y-polarized light) whose vibration plane is parallel to the YZ plane is converted into X-polarized light by the half-wave plate 30. The X-polarized light passes through the polarizing plate 27 and the screen unit 4 and is emitted forward. Of the background light L2, the linearly polarized light component (X-polarized light) whose vibration plane is parallel to the XZ plane is converted into Y-polarized light by the half-wave plate 30. The Y-polarized light is absorbed by the polarizing plate 27.

[0067] With reference to FIG. 10, a configuration example of the optical element section 5 when light containing circularly polarized light or elliptically polarized light as the main component is irradiated as the image light L1 will be described. A polarizing plate 27, the absorption axis of which is oriented in a predetermined direction, and a retardation plate 31 are used as the optical element section 5. The retardation plate 31 is disposed in front of the polarizing plate 27. When light containing circularly polarized light as a main component is irradiated as the image light L1, a quarter-wave plate is used as the retardation plate 31. The quarter-wave plate converts circularly polarized light into linearly polarized light whose polarization direction is the direction of the absorption axis of the polarizing plate 27. For example, the quarter-wave plate is arranged so that its optical axis intersects with the direction of the absorption axis of the polarizing plate 27 at an angle of 45 degrees. When light containing elliptically polarized light as a main component is irradiated as the image light L1, the retardation plate 31 is arranged so that the relationship between the direction of the major axis and ellipticity of the elliptically polarized light and the phase difference acquired by the retardation plate 31 is such that the elliptically polarized light can be converted into linearly polarized light whose polarization direction is the direction of the absorption axis of the polarizing plate 27. Of course, a quarter-wave plate may also be used.

[0068] By employing such a configuration, the image light L1 that is not reflected by the multiple reflecting surfaces 9 and that passes through the uneven surface 7 is converted into linearly polarized light whose vibration plane is a plane parallel to the absorption axis of the polarizing plate 27. The linearly polarized light is absorbed by the polarizing plate 27. On the other hand, the linearly polarized component of the background light L2, whose vibration plane is a plane including the direction of the transmission axis of the polarizing plate 27, passes through the screen unit 4 and is transmitted forward. This makes it possible to restrict the transmission of image light L1 to the rear side, and also to transmit at least a part of background light L2 incident from the rear side.

[0069] In the example shown in FIG. 10, light containing circularly polarized light as a main component is irradiated as the image light L1. The polarizing plate 27 is disposed so that the direction of the absorption axis is the X direction (horizontal direction). A quarter-wave plate is used as the retardation plate 31, and circularly polarized light is converted into linearly polarized light whose polarization direction is the direction of the absorption axis of the polarizing plate 27 (i.e., the X direction). When linearly polarized light whose polarization direction is the Y direction enters the retardation plate (quarter-wave plate) 31, it is converted into circularly polarized light.

[0070] 10B, the image light L1 transmitted through the screen unit 4 is converted by the retardation plate (quarter-wave plate) 31 into linearly polarized light (X-polarized light) whose vibration plane is parallel to the XZ plane. The X-polarized light is absorbed by the polarizing plate 27. Of the background light L2 incident on the optical element unit 5 from the rear side, the linearly polarized component (Y-polarized light) whose vibration plane is parallel to the YZ plane passes through the polarizing plate 27 and enters the retardation plate (quarter-wave plate) 31. The retardation plate (quarter-wave plate) 31 then converts the circularly polarized light into circularly polarized light. The circularly polarized light passes through the screen unit 4 and is emitted forward. Of the background light L2, the linearly polarized light component (X-polarized light) whose vibration plane is parallel to the XZ plane is absorbed by the polarizing plate 27.

[0071] [Light leakage suppression effect] In this embodiment, the transmission of the image light L1 to the rear side is restricted, thereby exerting the effect of suppressing light leakage to the rear side. When projecting an image using a transparent screen as in this embodiment, if a person behind the projector can see the light from the output port of the short-focus projector 2 (a so-called hot spot), this may cause an uncomfortable situation for that person. Furthermore, if the image light of the image that the viewer wants to enjoy in front of the camera is visible to a person behind the viewer, the content of the image will be revealed, which is undesirable from the viewpoint of privacy. By applying this technology, the effect of suppressing light leakage can be achieved, making it possible to suppress the above-mentioned problems.

[0072] [Surface reflection suppression effect] It is also possible that the image light L1 is specularly reflected from the screen surface 6. If the surface reflected light (specular reflection component) from the screen surface 6 becomes large, this may cause, for example, a reflection ghost of the image light L1, and unintended reflection or scattering due to unnecessary light may occur on the front side of the screen 3. As shown in Figures 7 to 10, light whose main component is linearly polarized light with its vibration plane parallel to the YZ plane is irradiated as image light L1. This light becomes a P-polarized component with respect to the screen surface 6, making it possible to suppress surface reflection. In other words, it is possible to achieve a surface reflection suppression effect, and to suppress the above-mentioned problems. The more light that is P-polarized with respect to the screen surface 6, i.e., the more linearly polarized light components with the polarization direction in the Y direction, the greater the surface reflection suppression effect. For example, image light L1 mainly composed of elliptically polarized light whose major axis is parallel to the YZ plane is irradiated. In this case, it is possible to achieve a high surface reflection suppression effect.

[0073] [Background light noise suppression effect] When the screen 3 is used as a transparent screen as in this embodiment, the background light L2 may behave like noise in a sense due to its transparency. For example, when viewing an image displayed on screen 3, sunlight may be reflected from the road, water, fields, etc., and overlap with the image seen by the viewer, making it very difficult to see. This type of background light noise can be a problem when viewing both the outside scenery and the projected image. Furthermore, this also becomes a problem when using an AR (Augmented Reality) application that projects information onto the screen 3 and superimposes it on specific information in the background.

[0074] The sunlight reflected from the road surface, water surface, etc. is light whose main component is linearly polarized light (X-polarized light) whose vibration plane is parallel to the XZ plane. Furthermore, when using an AR application, virtual objects are often displayed on Screen 3 in addition to the image displayed on the LCD or OLED display located behind the screen. In AR applications that also use information from displays such as electronic billboards found around town, it is desirable to be able to see both the information on the display and the projected image. Such LCD displays often have a function to absorb X-polarized light as a countermeasure against sunlight exposure, and output image light as Y-polarized light. 8 to 10, the X-polarized light of the background light L2 is restricted from being transmitted forward, and the Y-polarized light of the background light L2 is emitted forward. Therefore, it is possible to sufficiently suppress background light noise mainly composed of X-polarized light, and to sufficiently improve the visibility of the image displayed on the screen 3. In addition, it is possible to properly display the image output by Y-polarized light on the forward side, and it becomes possible to properly use AR applications. As a result, a very good viewing environment can be realized for viewers watching images in the front.

[0075] In this way, the polarizing plate 27 is arranged with the direction of the absorption axis appropriately set to correspond to the polarization state of the image light L1. In addition, a retardation plate (a half-wave plate, a quarter-wave plate, or any other wave plate that imparts a predetermined retardation) is appropriately arranged. This makes it possible to achieve the above-mentioned "leak light suppression effect," "surface reflection suppression effect," and "background light noise suppression effect." It should be noted that when a reflective polarizing plate is used as the polarizing plate 27, a reflection ghost may occur due to the image light L1 reflected by the polarizing plate 27. From this perspective, it can be said that a configuration using an absorptive polarizing plate as the polarizing plate 27 is preferable for realizing a good viewing environment. The screen 3 may include a layer that uniformly reduces transmittance. Furthermore, the layer may have a light control function that can actively control the transmittance.

[0076] [How to set the absorption axis direction of the polarizer] As described above, even when the direction of the absorption axis of the polarizing plate 27 is set to an arbitrary direction, the "leakage light suppression effect" can be achieved by appropriately controlling the polarization state of the image light L1. Therefore, the case where the direction of the absorption axis of the polarizing plate 27 is set to an arbitrary direction is also included in the present technology.

[0077] FIG. 11 is a schematic diagram for explaining an example of a method for setting the direction of the absorption axis of the polarizing plate 27. In FIG. FIG. 11A is a perspective view of the screen 3 when viewed obliquely from above. FIG. 11B is a top view of the screen 3 as seen from above. FIG. 11C is a side view of the screen 3 as viewed from the left and right.

[0078] As shown in Fig. 11, the screen 3 may be configured as a curved screen. That is, the screen 3 (the screen portion 4 and the optical element portion 5) may have a curved surface shape. For example, it is possible to design the shape of the screen 3 so that when viewed from the side in the vertical or horizontal direction, the screen 3 has a radius of curvature with an R number (mm) of around 100 to several thousand. Also, the screen 3 may be configured so that a localized region has a curved surface shape.

[0079] 11A to 11C, first, a predetermined reference point P is set within the screen 3. There are no particular limitations on the method for setting the reference point P, and any point suitable for displaying an image on the screen 3 may be used. For example, a point on the screen 3 that intersects with the optical axis of the image light L1 is set as the reference point P. The optical axis of the image light L1 can be defined as the central axis of the light flux of the image light L1 irradiated onto the screen 3, for example. Alternatively, the reference point P may be set in any manner, such as the center point of the screen 3, the point where the optical axis of the short focus projector 2 intersects, the center point of the image to be displayed, etc. Note that the center point of the screen 3, the point where the optical axis of the short focus projector 2 intersects, and the center point of the image to be displayed may coincide with the point where the optical axis of the image light L1 intersects.

[0080] First, a case where the configuration shown in FIGS. 7 to 9 is adopted as the optical element section 5 will be described. 11A, a plane including the normal to a reference point P in the screen 3 and the vertical direction (Y direction) is defined as a reference plane S. The direction of the absorption axis of the polarizing plate 27 is set so as to be perpendicular to the normal to the reference point P and parallel to the reference plane S. In this case, the direction perpendicular to both the normal direction and the absorption axis direction, i.e., the perpendicular direction to the reference plane S, is the horizontal direction (X direction). When the direction of the absorption axis of the polarizing plate 27 is set in this way, it is possible to achieve not only the "leak light suppression effect" but also the "surface reflection suppression effect" and the "background light noise suppression effect."

[0081] 10 is adopted as the optical element section 5, the direction of the absorption axis of the polarizing plate 27 is set so as to be parallel to the normal to the reference plane S. This makes it possible to achieve not only the "leak light suppression effect" but also the "surface reflection suppression effect" and the "background light noise suppression effect."

[0082] 1 to 10, the flat screen 3 is arranged along the vertical direction (Y direction). In this case, as shown in FIG. 1, the point where the screen 3 intersects with the optical axis O of the image light L1 is set as a predetermined reference point P. In this case, the reference plane S including the normal to the predetermined reference point P and the vertical direction is the YZ plane including the reference point P. The direction perpendicular to the normal at a given reference point P and parallel to the reference plane S is the Y direction (vertical direction). The direction parallel to the perpendicular to the reference plane S is the X direction (horizontal direction). 1 to 10, the configuration in which the absorption axis direction of the polarizing plate 27 is set in the Y direction and the configuration in which the absorption axis direction of the polarizing plate 27 is set in the X direction can also be said to be configurations in which a method of setting the absorption axis direction of the polarizing plate 27 using the reference plane S is adopted.

[0083] [Image display direction (direction)] FIG. 12 is a schematic diagram showing an example of setting the image display direction (direction). 12A and 12B are schematic diagrams showing an example of the configuration of the image projection system 1 relative to seats 33 where viewers sit. A viewer sits in seat 33 with the viewer facing forward (facing upward in the figure). An assumed viewing position 34 is set based on seat 33. The assumed viewing position 34 is a position where a user is assumed to view an image. The assumed viewing position 34 can also be said to be the viewing position where a user sitting in seat 33 views an image. For example, an estimated eye position of a viewer sitting in seat 33, an estimated head position of a viewer sitting in seat 33, etc. may be set as assumed viewing position 34. For example, average data on the structure of the human body may be used. Alternatively, the assumed viewing position 34 may be set based on the seat 33, such as the position of the top end of the backrest of the seat 33 or the center position of the seat 33.

[0084] 12A, a screen 3 is placed on the front right side relative to the viewer's direction. A short focus projector 2 is installed on the ceiling side, and image light L1 is irradiated onto the screen 3 from the front (from left to right in the figure). The screen 3 displays an image by diffusing and reflecting the irradiated image light L1 toward the assumed viewing position 34. In other words, the screen 3 is designed to diffusely reflect the irradiated image light L1 in a direction shifted to the left of the front (a diagonal left direction when viewed from the screen 3).

[0085] 12B, a screen 3 is placed in front of the viewer. A short focus projector 2 is installed on the ceiling side, and image light L1 is irradiated onto the screen 3 from the front (from the bottom to the top in the figure). In the example shown in FIG. 12B, the image projection system 1 is designed so that an image can be displayed to a viewer sitting in the right seat 33 of the two seats 33 in front of the screen 3. Therefore, the screen 3 displays an image by diffusing and reflecting the irradiated image light L1 toward the assumed viewing position 34 of the right-side seat 33. In other words, the screen 3 is designed to diffusely reflect the irradiated image light L1 in a direction shifted to the left of the front (diagonal left direction when viewed from the screen 3).

[0086] Here, the point on the screen 3 that intersects with the optical axis of the image light L1 is set as a reference point P, and a reference plane S is set. The configurations shown in Figures 12A and 12B can be said to satisfy the following two conditions. (Condition 1) The screen surface 6 is perpendicular to the reference plane S. (Condition 2) The assumed viewing position 34, which is assumed as the position where an image is viewed, is configured to deviate from the reference plane S. Note that (Condition 1) also includes a state in which the screen surface 6 is rotated around the X direction (left-right direction), that is, a state in which the screen surface 6 is tilted toward the front or rear side. In the case of a curved screen, by defining a tangent plane, it is possible to consider the same conditions. For example, if a tangent plane is defined at a reference point P, the tangent plane will be perpendicular to the reference plane S.

[0087] [Improved visibility] For example, in the positional relationship between the screen and the viewer as shown in Fig. 12, the viewer will not be sitting directly opposite the short focus projector 2 and the screen 3, but will be viewing the image from an angle. Therefore, improving visibility from an angle is extremely important. Increasing brightness is necessary to improve visibility, but simply increasing the light output of the short focus projector 2 increases the heat generated by the light source, and the housing size of the short focus projector 2 must be increased for cooling purposes, which makes it difficult to install in a narrow space such as the interior of a vehicle. In this technology, by appropriately designing the multiple reflective surfaces 9 included in the uneven surface 7, it is possible to easily realize a configuration such as that shown in Figures 12A and 12B (a configuration that satisfies the two conditions described above), and it is possible to display an image toward the intended viewing position 34. As a result, high visibility can be achieved, and the "visibility improvement effect" can be realized.

[0088] [Specific examples of uneven surface configurations] 13 to 15 are schematic diagrams showing specific configuration examples of the uneven surface 7. In FIG. In each figure, the width and pitch of the multiple reflecting surfaces 9 are shown very large. In reality, the width and pitch (period) of the multiple reflecting surfaces are designed to be on the order of μm. Each figure can also be considered as a partial enlargement of the uneven surface 7. Furthermore, in the cross section of the uneven surface 7, there are some portions where curved portions are shown schematically as straight lines. 13 to 15 employ the arrangement shown in Fig. 1. Although not shown, the screen surface 6 is parallel to the XY plane. The center position of each screen 3 is set as a predetermined reference point P. The perpendicular line at the predetermined reference point is parallel to the Z direction, and the reference plane S is a plane parallel to the YZ plane.

[0089] 13 to 15, FIG. 13A, FIG. 14A, and FIG. 15A are perspective views of the screen 3 as seen obliquely from the upper right. 13B, 14B, and 15B, a front view of the screen 3 is shown in the center. On the right side of the front view, a cross-sectional view of the screen 3 cut along a reference plane S is shown. Below the front view, a cross-sectional view of the screen 3 cut along a plane T perpendicular to the reference plane S is shown.

[0090] 13, a plurality of planar reflecting surfaces 9 are configured, each extending along the X direction (horizontal direction). Each reflecting surface 9 is designed to face upward in the Y direction (vertical direction). The reflecting surfaces 9 are configured so that their surfaces are parallel to each other. The connecting surfaces 10 are configured parallel to the XZ plane and connect the adjacent reflecting surfaces 9 together. The image light L1 irradiated onto the screen 3 is diffusely reflected upward in the vertical direction by the multiple reflecting surfaces 9. Therefore, the image display direction (direction) of the screen 3 shown in FIG. 13 is a direction directed upward in the vertical direction when viewed from the screen 3.

[0091] In the example shown in Fig. 14, a plurality of flat reflective surfaces 9 are configured to extend in an oblique direction when the screen 3 is viewed from the front. The uneven surface 7 shown in Fig. 14 is configured by rotating the uneven surface 7 shown in Fig. 13 clockwise around the reference point P when the screen 3 is viewed from the front. As shown in the two cross-sectional views of FIG. 14B, each reflecting surface 9 is designed to face upward in the Y direction (vertical direction) and to the right in the X direction (left-right direction). The image light L1 irradiated onto the screen 3 is diffusely reflected by the plurality of reflecting surfaces 9 toward the upper side in the vertical direction and toward the right side in the left-right direction. 14 is a direction toward the upper vertical side and toward the left side when viewed from the screen 3. In other words, the image display direction (direction) of the screen 3 is a direction toward the upper left when viewed from the screen 3.

[0092] 15, the screen 3 has a plurality of reflective surfaces 9 extending in a curved shape when viewed from the front. Specifically, the plurality of reflective surfaces 9 have a curved shape that curves from the right side toward the top side and bulges out to the lower left when viewed from the front. When the screen 3 is viewed from the front, the reflecting surfaces 9 are configured to be approximately concentric with the upper right corner as the center. As shown in the two cross-sectional views of FIG. 15B, each reflecting surface 9 is designed to face upward in the Y direction (vertical direction) and to the right in the X direction (left-right direction). The image light L1 irradiated onto the screen 3 is diffusely reflected by the plurality of reflecting surfaces 9 toward the upper side in the vertical direction and toward the right side in the left-right direction. 15 is a direction toward the upper vertical side and toward the left side when viewed from the screen 3. In other words, the image display direction (direction) of the screen 3 is a direction toward the upper left when viewed from the screen 3.

[0093] The configuration example shown in Fig. 13 is a configuration in which the image display direction (direction) is set in a one-dimensional vertical direction. Figs. 14 and 15 are configurations in which the image display direction (direction) is set in a two-dimensional vertical and horizontal direction. The configuration examples shown in Figs. 14 and 15 make it possible to easily realize the configuration shown in Fig. 12, thereby making it possible to achieve a "visibility improvement effect."

[0094] [Construction conditions for uneven surfaces] A description will be given of a characteristic configuration of the uneven surface 7 that can be employed in the present technology. Of course, the configuration described below is not necessarily essential for the present technology. (Configuration A) Each of the plurality of reflecting surfaces 9 is a flat surface and is configured so as not to be perpendicular to the reference plane S. This (Configuration A) is adopted in the configuration example shown in FIG. (Configuration B) Each of the multiple reflecting surfaces 9 is a curved surface, and is configured so that the tangent plane at the portion (intersection line) where it intersects with the reference plane S is not perpendicular to the reference plane S. This (Configuration B) is adopted in the configuration example shown in FIG.

[0095] Fig. 16 is a schematic diagram for explaining the tangential plane in (Configuration B). In Fig. 16, only one reflecting surface 9 is shown in the drawings other than the cross section. As shown in FIG. 16A, in each reflecting surface 9, the intersection angle between a tangent plane Q at a portion 36 where the reflecting surface 9 intersects with the reference plane S and the reference plane S is not orthogonal, which is (Configuration B). By employing (Configuration A) or (Configuration B), it is possible to easily realize a configuration such as that shown in FIG. 12, and it is possible to achieve the "visibility improvement effect." Of course, even in the configuration shown in FIG. 13, if the assumed viewing position 34 is set on the upper side in the vertical direction, the "visibility improvement effect" is realized.

[0096] (Configuration C) Each of the plurality of reflecting surfaces 9 is configured so that the normal at the intersection with the reference plane S faces the assumed viewing position 34. This achieves the "visibility improvement effect." Note that "the normal line faces toward the assumed viewing position 34" does not necessarily mean that the assumed viewing position 34 is located on an extension of the normal line. It also means that the normal line faces a range near the assumed viewing position 34. For example, a state in which the assumed viewing position 34 is contained within a cone with a 90-degree apex angle centered on the normal line is included in the state in which "the normal line faces toward the assumed viewing position 34." In addition, any state in which the assumed viewing position 34 is on the front side (normal line direction side) of the displayed image is included.

[0097] (Configuration D) The plurality of reflecting surfaces 9 are configured such that the components of the normals at the portions where the reflecting surfaces 9 intersect with the reference plane S, in the directions included in the reference plane S, are parallel to each other. 17 is a cross-sectional view (hatching is omitted) of the screen 3 cut along a reference plane S. In FIG. The component of the normal at portion 36 intersecting with reference plane S in the direction included in reference plane S is the component of the normal at intersecting portion 36 projected onto reference plane S. As shown in FIG. 17, components V at each of the multiple reflecting surfaces 9 are parallel to each other (Configuration D). This (Configuration D) is adopted in the configuration examples shown in Figures 13 and 14. Note that it is also possible to design the configuration shown in Figure 15 so that it becomes Configuration D. By adopting (Configuration D), it is possible to simplify the configuration of the uneven surface 7, and it is possible to produce the uneven surface 7 inexpensively through a simple process.

[0098] [Fresnel lens shape] FIG. 18 is a schematic diagram showing another example of the configuration of the uneven surface 7. In FIG. FIG. 19 is a schematic diagram for explaining an example of the Fresnel lens shape. Fig. 19 is a schematic diagram of the uneven surface 7 shown in Fig. 18 when viewed from above in the vertical direction. Note that Fig. 19 illustrates a small number of multiple reflecting surfaces 9 to make it easier to understand the Fresnel lens shape.

[0099] 18 and 19, the concave-convex surface 7 may be configured in a Fresnel lens shape. Surfaces corresponding to the lens surfaces of the Fresnel lens shape become a plurality of reflecting surfaces 9. Furthermore, surfaces corresponding to the rise surfaces of the Fresnel lens shape become a plurality of connecting surfaces 10. As illustrated in FIGS. 18A and 19A, in a configuration in which the reference plane S is located at the center of the Fresnel lens shape (a configuration in which the short focus projector 2 is placed in front), an image is displayed facing forward. 18B and 19B, in a configuration in which the reference plane S is shifted to the left from the center of the Fresnel lens shape (a configuration in which the short focus projector 2 is shifted to the left), an image is displayed toward the right side when viewed from the front of the screen 3. Therefore, it is possible to realize a configuration such as that shown in FIGS. For example, when a short-focus projector 2 or the like is used, the incident angles of the individual lights (e.g., pixel lights constituting each pixel) in the image light L1 may differ from one another. In such cases, employing a Fresnel lens shape is effective for high-quality image display.

[0100] [Application to vehicles] The image projection system 1 according to the present technology can be installed in a vehicle. 20 and 21 are schematic diagrams showing an example of an image projection system 1 mounted in a vehicle. 20 and 21, the interior of a vehicle is illustrated with the image projection system 1 and the viewer in the vehicle at the center. Figure 20 is a diagram created to include the entire vehicle. Figure 21 is an enlarged view of Figure 20, and Figures 21B and 21C show enlarged views of some areas inside the vehicle. Figures 20A and 21A are views seen from the front side of the vehicle, Figures 20B and 21B are views seen from the left side of the vehicle, and Figures 20C and 21C are views seen from above the vehicle.

[0101] In this embodiment, the screen 3 is configured in at least a partial area of ​​a window 39 of a vehicle 38. The entire area of ​​the window 39 may be configured with the screen 3, or only a partial area of ​​the window 39 may be configured with the screen 3. The window glass and the screen 3 may be integrally formed, or the screen 3 may be attached to the window glass.

[0102] 20 and 21, a screen 3a is installed on the right-side side window 39a next to the second-row seats, and a screen 3b is installed on the window 39b next to the third-row seats. 20A and 20B, the screens 3a and 3b are configured as flat screens, and are inclined toward the front side (inside the vehicle) of the screens 3a and 3b. Of course, a curved surface shape may be adopted that has a radius of curvature with an R number of around 100 to several thousand when viewed from the front of the vehicle 38, in accordance with the shape of the window 39 of the vehicle 38.

[0103] In this embodiment, the expected viewing position 34a is set at the headrest of the seat in the second row that is closest to the window 39a. The uneven surface 7 of the screen 3a is designed based on the expected viewing position 34a. Also, an assumed viewing position 34b is set at the headrest of the seat in the third row that is closest to the window 39b. The uneven surface 7 of the screen 3b is designed based on the assumed viewing position 34b.

[0104] Typically, by designing the screen 3a based on the assumed viewing position 34a, it is possible to realize a good viewing environment even for viewers seated at positions far from the screen 3a in the second row seats. For example, the assumed viewing position 34a may be set on the headrest of a seat in the second row that is located away from the screen 3a. Even in this case, it is possible to create a good viewing environment for the two viewers sitting in the second row seats. The assumed viewing position 34a may be set by combining the positions of the headrests of the seats in the second row. For example, the assumed viewing position 34a may be set at the midpoint between two headrests. Similarly, for the third-row seats, the expected viewing position 34b may be set by integrating the positions of the headrests of the respective seats. For example, the expected viewing position 34b may be set at the position of the head dress in the center of the three headrests.

[0105] The configuration illustrated in FIG. 12A can be adopted as the image projection system 1a including the screen 3a and the image projection system 1b including the screen 3b. By using the short focus projectors 2a and 2b, it is possible to project the image light L1 onto the screen 3 while avoiding the heads and bodies of the viewers (passengers in the vehicle), thereby realizing a good viewing environment. Furthermore, by appropriately adopting the above-described configuration of the optical element section 5, the polarization state of the image light L1, (Configuration A) to (Configuration D) regarding the uneven surface 7, and the Fresnel lens shape, it is possible to achieve the "effect of suppressing light leakage," "effect of suppressing surface reflection," "effect of suppressing background light noise," and "effect of improving visibility."

[0106] FIG. 22 is a schematic diagram showing an image projection system 1a in a vehicle. An image 40 is displayed on a window 39a from a short-focus projector 2a installed on the ceiling, providing a good viewing environment for viewers seated in the second row seats. For example, the "leak light suppression effect" prevents hot spots from being visible to pedestrians outside the vehicle, drivers of other vehicles, etc. Also, the content of images being enjoyed inside the vehicle will not be visible to pedestrians, drivers of other vehicles, etc., which is desirable from the perspective of protecting privacy. In addition, the "surface reflection suppression effect" makes it possible to suppress the projection of unnecessary image light L1 into the vehicle, preventing unintended reflections on the windshield and front side windows. As a result, it is possible to prevent the driver from being distracted while driving, and a high level of safety is demonstrated. Furthermore, the "background light noise suppression effect" makes it possible to sufficiently suppress background light noise, which is mainly composed of X-polarized light, and to sufficiently improve the visibility of images displayed on the screen 3a. It also makes it possible to properly display images output by Y-polarized light from an external display, etc., and to properly use AR applications. Furthermore, the "visibility improvement effect" allows the image to be displayed in the direction of the viewer, thereby achieving high visibility. For example, high visibility is achieved even when the image light L1 is irradiated onto the screen 3 while avoiding the head and body of the viewer (vehicle passenger).

[0107] 22, the image light L1 is also projected onto a frame 41 that holds the periphery of the window 39a (screen 3a). In this way, an image may be displayed not only on the screen 3a but also on members surrounding the screen 3a. For example, GUIs for switching the displayed content or operating the short focus projector 2 are displayed not on the screen 3a made of a transparent screen but on the surrounding members. This makes it possible to improve the operability for the viewer. Of course, the present invention is not limited to such an embodiment.

[0108] 23 and 24 are schematic diagrams showing other examples of the image projection system 1 mounted in a vehicle. In the example shown in FIGS. 23 and 24, the screen 3 is installed near the center console between the first and second row seats. For example, a light-transmitting partition is arranged between the first and second row seats. The partition and the screen 3 may be integrally configured, or the screen 3 may be attached to the partition. The partition may not be used and the screen 3 may be held by a predetermined holder. As shown in FIGS. 23A and 24B, the screens 3a and 3b are configured as flat screens and are arranged parallel to the vertical direction (Y direction).

[0109] In this embodiment, the expected viewing position 34 is set at the headrest of the right seat in the second row of seats. The uneven surface 7 of the screen 3 is designed based on the expected viewing position 34. That is, in this embodiment, an image is displayed with only the person sitting in the right seat of the second row seat as the viewer.

[0110] As the image projection system 1 including the screen 3, it is possible to employ the configuration illustrated in FIG. 12B. By using the short focus projector 2, it is possible to project the image light L1 onto the screen 3 while avoiding the heads and bodies of the viewers (passengers in the vehicle), thereby realizing a good viewing environment. Furthermore, by appropriately adopting the above-described configuration of the optical element section 5, the polarization state of the image light L1, (Configuration A) to (Configuration D) regarding the uneven surface 7, and the Fresnel lens shape, it is possible to achieve the "effect of suppressing light leakage," "effect of suppressing surface reflection," "effect of suppressing background light noise," and "effect of improving visibility."

[0111] The screen 3 can be installed at any position inside the vehicle. For example, the screen 3 may be installed on the front window or rear window.

[0112] As described above, in the image projection system 1 and screen 3 according to this embodiment, the image light L1 is diffused and reflected by the multiple reflective surfaces 9 included in the uneven surface 7. This makes it possible to display an image to viewers present in front of the screen. Furthermore, the optical element section 5 restricts transmission of the image light L1 to the rear side, and transmits part of the background light L2 incident from the rear side. This allows the screen 3 to be used as a transparent screen. It also makes it possible to prevent the image light L1 from leaking to the rear side. As a result, a good viewing environment is realized for the viewer.

[0113] When constructing a screen with a controllable directivity angle, it is possible to widen the viewing angle so that images can be viewed from various directions, and to adopt a structure that makes the brightness uniform over as wide an angle as possible. It is also possible to adopt a structure that is symmetrical with respect to the angle. As a result of such a structure, the brightness is maximum at the front and decreases in directions with large incident angles. Furthermore, to improve visibility from limited directions, such as in vehicles, the usual approach is to increase the brightness of the projector, but this requires cooling, which places a limit on the size that can be installed. The image projection system 1 and screen 3 according to this embodiment are able to achieve the various effects described above, and can provide a good viewing environment for viewers. Of course, the present invention is not limited to a case where all of the various effects described above are achieved simultaneously, and it is sufficient to adopt a configuration that can achieve each effect as appropriate.

[0114] <Other embodiments> The present technology is not limited to the above-described embodiments, and various other embodiments can be realized.

[0115] Regarding the configuration of the optical element unit 5, the optical characteristics may be controlled for each region in accordance with the incident angle (incident position) of the image light L1. For example, the direction of the absorption axis may be controlled for each region when viewing the polarizing plate 27 from the front. That is, the distribution of the absorption axes of the polarizing plate 27 may be appropriately controlled in accordance with the incident angle (incident position) of the image light L1. When a retardation plate (a half-wave plate, a quarter-wave plate, or any other wave plate that provides a predetermined retardation) is used, the optical characteristics may be controlled for each region in accordance with the distribution of the absorption axis.

[0116] For example, the image projection system and screen according to the present technology can be applied to any field or device without any limitations, and can be applied to any field or any device. For example, the present invention can be applied to any moving object, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, a robot, construction machinery, or an agricultural machine (tractor). Of course, this technology is not limited to mobile devices, but can be applied to any electronic device, such as mobile phones, smartphones, PCs, game consoles, digital cameras, audio equipment, TVs, projectors, car navigation systems, GPS terminals, wearable information devices (glasses-type, wristband-type), and IoT devices connected to the Internet, etc. Furthermore, the image projection system and screen according to the present technology may be used in any location where a transparent screen is used, such as any facility such as a control room, a library, or a show window.

[0117] The configurations and processing flows of the image projection system, screen, uneven surface, optical element unit, image projection device, short focus projector, vehicle, etc. described with reference to the drawings are merely one embodiment and can be arbitrarily modified without departing from the spirit of the present technology. In other words, any other configurations, algorithms, etc. for implementing the present technology may be adopted.

[0118] In this disclosure, to facilitate understanding of the explanation, words such as "approximately," "almost," and "roughly" are used as appropriate. However, there is no clear difference between using and not using words such as "approximately," "almost," and "roughly." That is, in the present disclosure, concepts that define shape, size, positional relationship, state, etc., such as "center," "central," "uniform," "equal," "same," "orthogonal," "parallel," "symmetrical," "extended," "axial direction," "cylindrical," "cylindrical," "ring-shaped," and "annular," are concepts that include "substantially center," "substantially central," "substantially uniform," "substantially equal," "substantially the same," "substantially orthogonal," "substantially parallel," "substantially symmetrical," "substantially extended," "substantially axial direction," "substantially cylindrical," "substantially cylindrical," "substantially ring-shaped," "substantially annular," and the like. For example, this also includes states that fall within a specified range (for example, a range of ±10%) based on criteria such as "perfectly centered," "perfectly central," "perfectly uniform," "perfectly equal," "perfectly the same," "perfectly perpendicular," "perfectly parallel," "perfectly symmetrical," "perfectly extended," "perfectly axial," "perfectly cylindrical," "perfectly cylindrical," "perfectly ring-shaped," and "perfectly annular." Therefore, even if the words "roughly," "almost," "approximately," etc. are not added, it may include concepts that can be expressed by adding "roughly," "almost," "approximately," etc. Conversely, a state expressed by adding "roughly," "almost," "approximately," etc. does not necessarily exclude a complete state.

[0119] In this disclosure, expressions using "more than," such as "greater than A" and "smaller than A," are expressions that comprehensively include both concepts that include equivalent to A and concepts that do not include equivalent to A. For example, "greater than A" is not limited to cases that do not include equivalent to A, but also includes "A or greater." Furthermore, "smaller than A" is not limited to "less than A," but also includes "A or less." When implementing the present technology, specific settings and the like may be appropriately adopted from the concepts included in "greater than A" and "smaller than A" so as to achieve the effects described above.

[0120] It is also possible to combine at least two of the features of the present technology described above. That is, the various features described in each embodiment may be arbitrarily combined without distinction between the embodiments. Furthermore, the various effects described above are merely examples and are not limiting, and other effects may also be achieved.

[0121] The present technology can also be configured as follows. (1) A screen that displays an image in response to irradiation with image light that is mainly composed of light in a predetermined polarization state, an uneven surface including a plurality of reflective surfaces that are light-transmitting and that diffuse and reflect the irradiated image light; an optical element section that is configured on a second side of the uneven surface opposite to a first side onto which the image light is irradiated, in accordance with a polarization state of the image light, and that restricts transmission of the image light to the second side and transmits at least a part of light incident from the second side; A screen comprising: (2) The screen according to (1), The image is displayed in response to irradiation of the image light whose main component is linearly polarized light, circularly polarized light, or elliptically polarized light. screen. (3) The screen according to (1) or (2), The optical element section has a polarizing plate whose light-shielding axis is oriented in a predetermined direction. screen. (4) The screen according to (3), The polarizing plate has a light-shielding axis that is oriented in the vertical direction. screen. (5) The screen according to (4), If a plane including a normal line and a vertical direction at a predetermined reference point in the screen is defined as a reference plane, then The direction of the light blocking axis of the polarizing plate is set to be perpendicular to the normal line and parallel to the reference plane. screen. (6) The screen according to (5), The image is displayed in response to irradiation of the image light, the main component of which is linearly polarized light whose vibration plane is the reference plane. screen. (7) A screen according to any one of (3) to (6), When the polarizing plate is a first polarizing plate, The optical element portion is a quarter-wave plate disposed on the second side of the first polarizing plate and configured to convert linearly polarized light having a polarization direction in the direction of the light-blocking axis of the first polarizing plate into circularly polarized light; a second polarizing plate disposed on the second side of the quarter-wave plate, the second polarizing plate having a light-blocking axis perpendicular to the light-blocking axis of the first polarizing plate; screen. (8) A screen according to any one of (3) to (6), The optical element unit includes a half-wave plate that is disposed on the second side of the polarizing plate and converts linearly polarized light having a polarization direction in the direction of the light-blocking axis of the polarizing plate into linearly polarized light having a polarization direction perpendicular to the direction of the light-blocking axis of the polarizing plate. screen. (9) The screen according to (5), The image is displayed in response to irradiation of the image light, the main component of which is elliptically polarized light whose major axis is parallel to the reference plane. screen. (10) The screen according to (3) or (4), displaying the image in response to irradiation of the image light containing circularly polarized light as a main component; The optical element unit includes a quarter-wave plate that is disposed on the first side of the polarizing plate and converts circularly polarized light into linearly polarized light whose polarization direction is the direction of the light blocking axis of the polarizing plate. screen. (11) The screen according to (3) or (4), displaying the image in response to irradiation of the image light containing elliptically polarized light as a main component; The optical element unit has a retardation plate that is disposed on the first side of the polarizing plate and converts elliptically polarized light into linearly polarized light whose polarization direction is the direction of the light blocking axis of the polarizing plate. screen. (12) The screen according to (10) or (11), If a plane including a normal line and a vertical direction at a predetermined reference point in the screen is defined as a reference plane, then The direction of the light blocking axis of the polarizing plate is set to be parallel to the normal to the reference plane. screen. (13) The screen according to (5) or (12), The predetermined reference point within the screen is a point where the screen intersects with the optical axis of the image light. screen. (14) A screen according to any one of (1) to (13), The plurality of reflecting surfaces are made of a light-transmitting material and are configured as rough surfaces. screen. (15) A screen according to any one of (1) to (14), The plurality of reflecting surfaces are configured by disposing a light diffusing material on surfaces made of a light-transmitting material. screen. (16) A screen according to any one of (1) to (15), If a plane including a normal line and a vertical direction at a predetermined reference point in the screen is defined as a reference plane, then Each of the plurality of reflecting surfaces is a plane and is configured not to be perpendicular to the reference plane. screen. (17) A screen according to any one of (1) to (16), If a plane including a normal line and a vertical direction at a predetermined reference point in the screen is defined as a reference plane, then Each of the plurality of reflecting surfaces is a curved surface, and is configured so that a tangent plane at a portion where the tangent plane intersects with the reference plane is not perpendicular to the reference plane. screen. (18) an image projection device that projects image light that is mainly composed of light in a predetermined polarization state; an uneven surface including a plurality of reflective surfaces that are light-transmitting and that diffuse and reflect the irradiated image light; an optical element section that is configured on a second side of the uneven surface opposite to a first side onto which the image light is irradiated, in accordance with a polarization state of the image light, and that restricts transmission of the image light to the second side and transmits at least a part of light incident from the second side; a screen having An image projection system comprising: (19) an image projection device that projects image light that is mainly composed of light in a predetermined polarization state; an uneven surface including a plurality of reflective surfaces that are light-transmitting and that diffuse and reflect the irradiated image light; an optical element section that is configured on a second side of the uneven surface opposite to a first side onto which the image light is irradiated, in accordance with a polarization state of the image light, and that restricts transmission of the image light to the second side and transmits at least a part of light incident from the second side; a screen having A vehicle equipped with: (20) The vehicle according to (19), further comprising: It has a window, The screen is configured in at least a part of the window area. vehicle. (21) The screen according to (3), the polarizing plate is an absorption polarizing plate, The light-blocking axis is an absorption axis screen. (22) The screen according to (3), the polarizing plate is a reflective polarizing plate, The light blocking axis is the reflection axis screen. (23) A screen according to any one of (1) to (22), The image is displayed in response to irradiation of the image light by a short focus projector. screen. (24) A screen according to any one of (1) to (23), Each of the plurality of reflecting surfaces is configured to be oriented in a direction corresponding to a predetermined image display direction. A screen comprising: (25) A screen according to any one of (1) to (24), If a plane including a normal line and a vertical direction at a predetermined reference point in the screen is defined as a reference plane, then The assumed viewing position, which is assumed as a position where the image is viewed, is configured to deviate from the reference plane. screen. (26) A screen according to any one of (1) to (25), If a plane including a normal line and a vertical direction at a predetermined reference point in the screen is defined as a reference plane, then Each of the plurality of reflecting surfaces is configured so that a normal at a portion where the reflecting surface intersects with the reference plane faces toward the assumed viewing position. screen. (27) A screen according to any one of (1) to (26), If a plane including a normal line and a vertical direction at a predetermined reference point in the screen is defined as a reference plane, then The plurality of reflecting surfaces are configured such that the components of the normals of the reflecting surfaces at the intersections with the reference plane, which are in the direction included in the reference plane, are parallel to each other. screen. (28) A screen according to any one of (1) to (27), The uneven surface includes a plurality of connecting surfaces that connect adjacent ones of the plurality of reflecting surfaces. A screen comprising: (29) A screen according to any one of (1) to (28), If a plane including a normal line and a vertical direction at a predetermined reference point in the screen is defined as a reference plane, then The screen surface is perpendicular to the reference plane. screen. [Explanation of symbols]

[0122] L1...Image light L2…background light O…Optical axis S...Reference surface 1...Image projection system 2...Short focus projector (image projection device) 3...Screen 4...Screen section 5...Optical element section 7…Uneven surface 9…Reflective surface 10...Connection surface 25...Light diffusion material 27...Polarizing plate (first polarizing plate) 28...1 / 4 wavelength plate 29...Polarizing plate (second polarizing plate) 30…1 / 2 wavelength plate 31...Retardation plate 34...Expected viewing position 38...Vehicle 39...Window

Claims

1. A screen that displays an image in response to irradiation with image light that is mainly composed of light in a predetermined polarization state, an uneven surface including a plurality of reflective surfaces that are light-transmitting and that diffuse and reflect the irradiated image light; an optical element section configured in correspondence with the polarization state of the image light on a second side of the uneven surface opposite to a first side onto which the image light is irradiated, the optical element section restricting transmission of the image light to the second side and transmitting at least a part of light incident from the second side; Equipped with The optical element portion is a first polarizing plate whose light-shielding axis is oriented in a predetermined direction; a quarter-wave plate disposed on the second side of the first polarizing plate and configured to convert linearly polarized light having a polarization direction in the direction of the light-blocking axis of the first polarizing plate into circularly polarized light; a second polarizing plate disposed on the second side of the quarter-wave plate, the second polarizing plate having a light-blocking axis perpendicular to the light-blocking axis of the first polarizing plate; screen.

2. 2. The screen of claim 1, The image is displayed in response to irradiation of the image light whose main component is linearly polarized light, circularly polarized light, or elliptically polarized light. screen.

3. 2. The screen of claim 1, The first polarizing plate has a light-shielding axis that is oriented in a vertical direction. screen.

4. 4. The screen of claim 3, If a plane including a normal line and a vertical direction at a predetermined reference point in the screen is defined as a reference plane, then The direction of the light-shielding axis of the first polarizing plate is set to be perpendicular to the normal line and parallel to the reference plane. screen.

5. 5. The screen of claim 4, The image is displayed in response to irradiation of the image light, the main component of which is linearly polarized light whose vibration plane is the reference plane. screen.

6. 5. The screen of claim 4, The image is displayed in response to irradiation of the image light, the main component of which is elliptically polarized light whose major axis is parallel to the reference plane. screen.

7. 5. The screen of claim 4, The predetermined reference point within the screen is a point where the screen intersects with the optical axis of the image light. screen.

8. 2. The screen of claim 1, The plurality of reflecting surfaces are made of a light-transmitting material and are configured as rough surfaces. screen.

9. 2. The screen of claim 1, The plurality of reflecting surfaces are configured by disposing a light diffusing material on surfaces made of a light-transmitting material. screen.

10. 2. The screen of claim 1, If a plane including a normal line and a vertical direction at a predetermined reference point in the screen is defined as a reference plane, then Each of the plurality of reflecting surfaces is a plane and is configured not to be perpendicular to the reference plane. screen.

11. 2. The screen of claim 1, If a plane including a normal line and a vertical direction at a predetermined reference point in the screen is defined as a reference plane, then Each of the plurality of reflecting surfaces is a curved surface, and is configured so that a tangent plane at a portion where the tangent plane intersects with the reference plane is not perpendicular to the reference plane. screen.

12. an image projection device that projects image light that is mainly composed of light in a predetermined polarization state; an uneven surface including a plurality of reflective surfaces that are light-transmitting and that diffuse and reflect the irradiated image light; an optical element section configured in correspondence with the polarization state of the image light on a second side of the uneven surface opposite to a first side onto which the image light is irradiated, the optical element section restricting transmission of the image light to the second side and transmitting at least a part of light incident from the second side; a screen having Equipped with The optical element portion is a first polarizing plate whose light-shielding axis is oriented in a predetermined direction; a quarter-wave plate disposed on the second side of the first polarizing plate and configured to convert linearly polarized light having a polarization direction in the direction of the light-blocking axis of the first polarizing plate into circularly polarized light; a second polarizing plate disposed on the second side of the quarter-wave plate, the second polarizing plate having a light-blocking axis perpendicular to the light-blocking axis of the first polarizing plate; Image projection system.

13. an image projection device that projects image light that is mainly composed of light in a predetermined polarization state; an uneven surface including a plurality of reflective surfaces that are light-transmitting and that diffuse and reflect the irradiated image light; an optical element section configured in correspondence with the polarization state of the image light on a second side of the uneven surface opposite to a first side onto which the image light is irradiated, the optical element section restricting transmission of the image light to the second side and transmitting at least a part of light incident from the second side; a screen having Equipped with The optical element portion is a first polarizing plate whose light-shielding axis is oriented in a predetermined direction; a quarter-wave plate disposed on the second side of the first polarizing plate and configured to convert linearly polarized light having a polarization direction in the direction of the light-blocking axis of the first polarizing plate into circularly polarized light; a second polarizing plate disposed on the second side of the quarter-wave plate, the second polarizing plate having a light-blocking axis perpendicular to the light-blocking axis of the first polarizing plate; vehicle.

14. 14. The vehicle of claim 13, further comprising: It has a window, The screen is configured in at least a part of the window area. vehicle.

Images