Screens, video display devices

Abstract

To provide a transmissive screen and a picture display device that have a sufficient transparency and can display a bright and excellent picture.SOLUTION: A screen 10 includes: a picture light deflection unit 10A for changing the direction of a part of at least incident picture light; and a picture light diffusion unit 10B for diffusing a part of at least incident picture light. The picture light deflection unit 10A and the picture light diffusion unit 10B are located in different positions in the thickness direction of the screen 10. The picture display device includes a screen 10 and a picture source for projecting picture light on the screen 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a screen and an image display device. [Background technology]

[0002] Conventionally, there have been known transmission-type and reflection-type screens that display images using image light projected from an image source, and image display devices that use such screens. In recent years, there has been an increasing demand for highly transparent screens that can be installed in store show windows or the like to display images and that allow a clear view of the scenery on the other side of the screen when no image light is projected.

[0003] As a transparent screen, various types of transmission screens have been developed, including a diffusion layer containing a diffusion material that diffuses light (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-027026 [Patent Document 2] Japanese Patent Application Publication No. 2019-174546 Summary of the Invention [Problem to be solved by the invention]

[0005] In a transmissive screen equipped with such a light diffusion layer, increasing the diffusion strength of the light diffusion layer can brighten the image displayed on the screen, but this can also cause problems such as a decrease in image contrast and transparency, causing the background image observed through the screen to appear cloudy and whitish. Furthermore, if the diffusion strength of such a screen is reduced in order to maintain high transparency, when an image is projected from the front of the screen, the image light reaches the viewer without being diffused. To avoid this, if the image light is projected obliquely from below the screen, most of the image light is directed obliquely upward from the screen, reducing the amount of image light reaching the viewer and resulting in a dark image, resulting in a significant decrease in the utilization efficiency of the image light. With such a screen, it is difficult to achieve both image contrast and brightness while maintaining transparency.

[0006] An object of the present invention is to provide a transmission screen and an image display device that have sufficient transparency and display bright and good images. [Means for solving the problem]

[0007] The present invention solves the above-mentioned problems by the following means: For ease of understanding, the following description will be given with reference to the corresponding embodiments of the present invention, but the present invention is not limited to these. The first invention is a screen (10, 30) comprising an image light deflection section (10A, 20A) that changes the direction of at least a portion of the incident image light, and an image light diffusion section (10B, 30B) that diffuses at least a portion of the incident image light, characterized in that the image light deflection section and the image light diffusion section are provided at different positions in the thickness direction of the screen. A second invention is a screen (10) characterized in that, in the screen of the first invention, the image light diffusion section (10B) is arranged on the light-entering side of the image light deflection section (10A, 20A) in the thickness direction of the screen, and diffuses light incident from an oblique direction more than light incident at an incident angle of 0°. A third invention is a screen (10) according to the first or second invention, characterized in that the image light diffusion section (10B) is arranged on the light-entering side of the image light deflection section (10A, 20A) in the thickness direction of the screen, and is a light control layer (16) that diffuses and transmits light incident at an incident angle within a specific angular range to a greater extent than light incident at an incident angle outside the specific angular range. The fourth invention is a screen (10) according to the third invention, characterized in that light incident at an incident angle outside the specific angular range is transmitted without being diffused or with such little diffusion that it can be considered to be almost undiffused. The fifth invention is a screen (10, 30) characterized in that, in the screen of any of the first to fourth inventions, it has a light entrance surface (M1) through which image light enters and a light exit surface (M2) opposite the light entrance surface and through which the image light exits, the image light deflection unit (10A, 20A) comprises a light-transmitting resin layer (12, 22) and a plurality of reflective surfaces (13) arranged inside the resin layer and reflecting at least a portion of the incident light, and at least a portion of the image light is reflected by the reflective surfaces to change its direction toward the light exit surface. A sixth invention is a screen (10, 30) according to the fifth invention, characterized in that the reflecting surface (13) forms an angle θ1 with a plane parallel to the screen surface in a cross section parallel to the arrangement direction and the thickness direction of the screen, and the angle θ1 is 70° or more. A seventh aspect of the present invention is a screen (10, 30) according to the sixth aspect of the present invention, characterized in that the angle θ1 decreases toward one side along the arrangement direction of the reflecting surfaces (13). An eighth invention is a screen (10, 30) characterized in that, in the screen of any one of the fifth to seventh inventions, the reflecting surfaces (13) have gaps between them in the arrangement direction when viewed from the normal direction of the screen surface of the screen. A ninth invention is a screen (10, 30) characterized in that, in the screen of any one of the fifth to eighth inventions, the reflective surfaces (13) are arranged concentrically around a point (C) located outside the display area of ​​the screen when viewed from the normal direction of the screen surface of the screen. A tenth invention is a screen (10, 30) characterized in that, in the screen of any one of the fifth to ninth inventions, the resin layer (12, 22) has a first resin layer (121, 221) located on the light incident side and a second resin layer (122, 222) arranged adjacent to the light exit side of the first resin layer, the first resin layer has a plurality of unit optical shapes (121a, 221a) arranged at the boundary surface with the second resin layer, the unit optical shapes have a polygonal shape in a cross section parallel to the arrangement direction and the thickness direction of the screen, and the reflecting surface (13) is formed on at least a part of a surface of the unit optical shape that forms an angle with a plane parallel to the screen surface. An eleventh invention is a screen (10) characterized in that, in the screen of the tenth invention, the unit optical shapes (121a) are triangular in a cross section parallel to the arrangement direction and the thickness direction of the screen, have a first surface (121b) and a second surface (121c) intersecting therewith, the angle (θ1) that the first surface makes with a plane parallel to the screen surface is larger than the angle (θ2) that the second surface makes with a plane parallel to the screen surface, and the reflective surface is formed on at least a part of the first surface. A twelfth invention is a screen (10) characterized in that, in the screen of the tenth invention, the unit optical shapes (221a) are trapezoidal in cross section parallel to their arrangement direction and the thickness direction of the screen, and have a first surface (221b), a second surface (221c) opposite to the first surface in the arrangement direction of the unit optical shapes, and a top surface (221d) located between the first surface and the second surface and closest to the light output side, the first surface being angled with respect to a plane parallel to the screen surface, and the reflective surface being formed on at least a part of the first surface. A thirteenth invention is a screen (10) according to any one of the fifth to twelfth inventions, characterized in that the screen has transparency, and the reflecting surface (13) is provided by a low refractive index layer that has light transmittance and has a refractive index lower than that of the resin layer (12). A fourteenth invention is a screen (10) according to any one of the fifth to twelfth inventions, characterized in that the screen has transparency, and the reflective surface (13) is provided by a semi-transparent reflective layer that reflects part of the incident light and transmits part of the incident light. A fifteenth invention is a screen (30) characterized in that, in the screen of the first or second invention, the image light diffusion section (30B) is arranged on the light exit side or light entrance side of the image light deflection section (10A, 20A) in the thickness direction of the screen, and is a light diffusion layer (38) containing a diffusion material that diffuses light. The 16th invention is a screen (10, 30) that is any of the screens of the first to fifteenth inventions, characterized in that it is a transmissive screen having a light entrance surface (M1) through which image light enters and a light exit surface (M2) opposite the light entrance surface and through which the image light exits, and that displays an image by emitting the image light projected onto the light entrance surface from the light exit surface. A seventeenth aspect of the invention is an image display device (1) including a screen (10, 30) according to any one of the first to sixteenth aspects of the invention, and an image source (LS) that projects image light onto the screen. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a transmission screen and an image display device that have sufficient transparency and display bright and good images. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing an image display device 1 of a first embodiment. [Figure 2] 1 is a diagram showing a layer structure of a screen 10 according to a first embodiment. [Figure 3] 2A and 2B are diagrams illustrating an image light deflection unit 10A according to the first embodiment. [Figure 4] 3A and 3B are diagrams illustrating a reflecting surface 13 in the first embodiment. [Figure 5] 3A and 3B are diagrams illustrating image light incident on an image light deflection unit 10A according to the first embodiment. [Figure 6] 3A and 3B are diagrams illustrating the light control effect of the light control layer 16. FIG. [Figure 7] 2 is a diagram showing an example of image light and external light incident on the screen 10 of the first embodiment. FIG. [Figure 8] 10A and 10B are diagrams illustrating an image light deflection unit 20A according to a second embodiment. [Figure 9] FIG. 10 is a diagram showing a layer structure of a screen 30 according to a third embodiment. [Figure 10] 10A and 10B are diagrams illustrating a modified image light deflection section 60A. [Figure 11] 10A and 10B are diagrams illustrating a modified image light deflection section 70A. [Figure 12] 10A and 10B are diagrams illustrating a modified image light deflection section 80A. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings, etc. Note that the drawings shown below, including Fig. 1, are schematic diagrams, and the size and shape of each part are appropriately exaggerated to facilitate understanding. In this specification, terms specifying shapes or geometric conditions, such as parallel and orthogonal, are intended to include not only their strict meanings but also states that perform similar optical functions and have an error that can be considered as parallel or orthogonal (a state that is approximately equal).

[0011] In this specification, the numerical values ​​such as dimensions of each component and the names of materials are examples of embodiments, and are not limited to these, and may be selected and used as appropriate. In this specification, the terms plate, sheet, film, etc. are used. Generally, the terms plate, sheet, and film are used in order of increasing thickness, and this specification follows suit. However, since there is no technical significance in this distinction, these terms can be used interchangeably as appropriate. In this specification, the screen surface refers to a surface that is in the planar direction of the screen when viewed as a whole, and is parallel to the image plane (display surface) of the screen.

[0012] (First embodiment) Fig. 1 is a diagram showing an image display device 1 according to a first embodiment, showing the image display device 1 as viewed from the side (the +X side, which will be described later). The image display device 1 has a screen 10, an image source LS, etc., and is a so-called rear projection type image display device that projects image light from the image source LS onto the screen 10 from one side of the screen 10, transmits the image, and displays the image so that it can be seen by an observer O1 located on the other side. In this embodiment, as an example, the image display device 1 is applied to a shop window and the screen 10 is fixed by being attached to the glass of the window, etc. However, the image display device 1 is not limited to this, and can also be applied to, for example, an indoor partition or an image display at an exhibition, etc.

[0013] For ease of understanding, an XYZ Cartesian coordinate system is provided where appropriate in each of the following figures, including Figure 1. In this coordinate system, the left-right direction of the screen of screen 10 is the X direction, the up-down direction is the Y direction, and the thickness direction of screen 10 is the Z direction. The screen of screen 10 is parallel to the XY plane, and the thickness direction of screen 10 (Z direction) is perpendicular to the screen of screen 10. Furthermore, the direction toward the right side of the screen in the left-right direction as viewed from observer O1 positioned directly in front of the light-emitting side (observer side) of screen 10 is the +X direction, the direction toward the top of the screen in the up-down direction is the +Y direction, and the direction from the light-receiving side (image source side) to the light-emitting side (observer side) in the thickness direction is the +Z direction. Furthermore, in the following description, unless otherwise specified, the up-down direction of the screen, the left-right direction of the screen, and the thickness direction refer to the up-down direction (vertical direction), the left-right direction (horizontal direction), and the thickness direction (depth direction) of the screen when the image display device 1 and the screen 10 are in use, and are assumed to be parallel to the Y direction, X direction, and Z direction, respectively.

[0014] The image source LS is an image projection device that projects image light L onto the screen 10, and is, for example, a short-focus projector. When the image display device 1 is in use, this image source LS is located in the center of the screen 10 in the left-right direction and vertically below the screen of the screen 10 (towards the -Y side) when the screen (display area) of the screen 10 is viewed from the front (normal direction of the screen surface) of the light output side (+Z side). The image source LS can project the image light L obliquely in the depth direction (Z direction) from a position that is much closer to the surface of the screen 10 than a conventional general-purpose projector. Therefore, compared to a conventional general-purpose projector, the image source LS has a shorter projection distance of the image light L to the screen 10, a larger incident angle at which the projected image light L is incident on the screen 10, and a larger amount of change in the incident angle (amount of change from minimum to maximum).

[0015] The screen 10 is a transmissive screen that transmits and displays image light L projected by an image source LS, and has a light-entering surface M1 through which the image light L enters and an opposing light-exiting surface M2 through which the image light L exits. The screen 10 is transparent so that the scenery on the other side of the screen 10 can be observed from both the light-exiting side and the light-entering side, for example, when the screen 10 is not in use and no image light is being projected. In this embodiment, an example will be described in which the screen (display area) of the screen 10 has a substantially rectangular shape in use, with the longer side extending in the left-right direction of the screen when viewed from the viewer O1 on the light exit side (+Z side). The screen 10 has a diagonal screen size of approximately 40 to 100 inches and an aspect ratio of 16:9. However, the screen size of the screen 10 is not limited to this, and may be, for example, smaller than 40 inches, and the size and shape can be selected appropriately depending on the purpose of use, the environment in which it is used, etc.

[0016] In the screen 10 of this embodiment, for example, a light-transmitting support plate (not shown) is integrally bonded (or partially fixed) to the light-emitting side (+Z side) surface via a light-transmitting bonding layer (not shown), thereby maintaining the flatness of the screen. However, without being limited to this, a support plate (not shown) may be disposed on the light-receiving side (-Z side) surface of the screen 10. The support plate is a light-transmitting, highly rigid, flat-plate-like member, and may be made of a resin such as acrylic resin or PC resin, or glass, etc. In this embodiment, the support plate is a glass plate of a shop window or the like. However, the screen 10 is not limited to this, and may have a configuration in which its four sides are supported by a frame member (not shown) or the like, thereby maintaining its flatness.

[0017] Fig. 2 is a diagram showing the layer structure of the screen 10 of the first embodiment. Fig. 2 shows an enlarged portion of a cross section that passes through point A (see Fig. 1) which is the center of the screen (the geometric center of the screen) on the light-emitting side (the observer side, +Z side) of the screen 10, is parallel to the up-and-down direction of the screen (the Y direction), and is perpendicular to the screen surface (parallel to the Z direction which is the thickness direction). The screen 10 includes an image light deflection unit 10A that changes (deflects) the traveling direction of the image light, and an image light diffusion unit 10B that diffuses at least the image light, and these are provided at different positions in the thickness direction (Z direction) of the screen 10. In this embodiment, the image light deflection unit 10A is provided on the light output side of the image light diffusion unit 10B. 2, the screen 10 of this embodiment includes, in order from the light incident side (-Z side), a light control layer 16, a bonding layer 17, a first base material layer 11, a resin layer 12, a reflecting surface 13, and a second base material layer 15. The image light deflection section 10A is the resin layer 12 and the reflecting surface 13, and the image light diffusion section 10B is the light control layer 16.

[0018] The first base layer 11 is a sheet-like member having optical transparency. The first base layer 11 has a resin layer 12 formed integrally on its light-emitting side (observer side, +Z side). The first base layer 11 is formed from, for example, a polyester resin such as PET (polyethylene terephthalate) having high light transmittance, an acrylic resin, a styrene resin, an acrylic-styrene resin, a PC (polycarbonate) resin, an alicyclic polyolefin resin, a TAC (triacetyl cellulose) resin, or the like.

[0019] The resin layer 12 is a light-transmitting layer formed on the light-emitting side (+Z side) of the first base layer 11. The resin layer 12 has a plurality of reflective surfaces 13 arranged therein. The resin layer 12 of this embodiment is made of an ultraviolet-curable resin having high light transmittance, but is not limited to this and may be made of other ionizing radiation-curable resins such as electron beam-curable resins. The reflecting surface 13 is a reflecting surface that reflects at least a part of the incident light. The reflecting surfaces 13 of this embodiment are provided inside the resin layer 12 and arranged at predetermined intervals.

[0020] 3 is a diagram illustrating the image light deflection section 10A of the first embodiment, which shows a further enlarged view of the image light deflection section 10A in the cross section of the screen 10 shown in FIG. Fig. 4 is a diagram illustrating the reflecting surface 13 of the first embodiment. Fig. 4 shows the image light deflection unit 10A as viewed from the light output side (+Z side), and for ease of understanding, only the image light deflection unit 10A is shown. 4, the reflecting surfaces 13 of this embodiment have a shape (arc shape) that is a part of a perfect circle, and a plurality of them are arranged concentrically around point C, which is located outside the image plane (display area) of the screen 10. This point C is located outside the display area of ​​the screen 10. The arrangement pitch of the reflecting surfaces 13 is P.

[0021] In this embodiment, point C is located at the center of the screen in the left-right direction (X direction) and outside the screen on the lower side (-Y side), as shown in Fig. 4. Furthermore, when the screen 10 is viewed from the front, points C and A are located on the same straight line parallel to the screen's up-down direction (Y direction), as shown in Fig. 4. However, the positional relationship between the image source LS and the viewer relative to the screen 10 can be set appropriately depending on the environment in which the image display device 1 is used, and the position of point C relative to the screen 10 can also be set appropriately accordingly.

[0022] 3, reflecting surface 13 of this embodiment is inclined so that the end on the light-incident side (-Z side) is located closer to image source LS (lower in the vertical direction of the screen) than the end on the light-exiting side (+Z side) in the arrangement direction of reflecting surface 13. The angle that reflecting surface 13 makes with a plane parallel to the screen surface is θ1. In the cross section shown in Fig. 3, the angle formed by the plane (shown by the dashed line in Fig. 3, hereinafter referred to as the connecting plane) connecting the light-entering end of reflecting surface 13 to the light-exiting end (point t1) of reflecting surface 13 adjacent to the lower side (image source side) of that reflecting surface 13 in the arrangement direction of reflecting surfaces 13 and the plane parallel to the screen surface is θ2. Although this connecting plane is shown by the dashed line, in reality it is difficult to see visually. It is preferable that the angle θ1 is 70° or more from the viewpoint of efficiently directing the image light toward the viewer O1 positioned in the front direction on the light output side (+Z side). In this embodiment, the angle θ1 is greater than the angle θ2, ie, θ1>θ2.

[0023] As shown in Figure 3, in a cross section parallel to the arrangement direction of the reflecting surfaces 13 and the thickness direction of the screen 10, the reflecting surfaces 13 and the connecting surface intersect at point t1, thereby forming a unit optical shape that is convex toward the light output side with point t1 as its vertex. That is, the resin layer 12 of this embodiment has a first resin layer 121 located on the first base material layer side (-Z side) and a second resin layer 122 located adjacent to the first resin layer 121 on the second base material layer side (+Z side), and is formed in such a manner that multiple unit optical shapes 121a are arranged at the boundary surface between the first resin layer 121 and the second resin layer 122. The first resin layer 121 and the second resin layer 122 are made of the same material, have the same refractive index, and are connected at the connecting surface.

[0024] The image light deflection unit 10A in which a plurality of reflective surfaces 13 are arranged inside the resin layer 12 as in this embodiment can be produced, for example, by molding a first resin layer in which a plurality of unit optical shapes as described above are arranged on one side, forming a layer for forming a reflective surface 13 on a predetermined surface of the unit optical shape, and then forming a second resin layer on top of that to fill in the unevenness caused by the unit optical shapes. In this embodiment, an example will be described in which the cross section of the unit optical shapes is triangular in a cross section parallel to the arrangement direction of the unit optical shapes and the thickness direction of the image light deflection unit. Note that the cross section of such unit optical shapes may be trapezoidal or another polygonal shape.

[0025] The unit optical shapes 121a are each a part of a perfect circle (arc-shaped), like the reflecting surface 13 shown in Figure 4, and are arranged in multiple concentric circles with a point C located outside the image surface (display area) of the screen 10 as the center. 3 is a substantially triangular shape convex toward the light-emitting side, and has a first surface 121b located below (on the -Y side of) point t1, which is the vertex, and a second surface 121c that intersects with first surface 121b at point t1 and is located above (on the +Y side of) point t1. Reflecting surface 13 is provided on first surface 121b, and second surface 121c corresponds to a connecting surface. The arrangement pitch of the unit optical shapes 121a is equal to the arrangement pitch P of the reflecting surfaces 13, and the angle that the first surface 121b makes with a plane parallel to the screen surface (XY plane) is θ1. The angle that the second surface 121c makes with a plane parallel to the screen surface (XY plane) is θ2.

[0026] 3, if the width occupied by the reflecting surfaces 13 in the arrangement direction is W1 and the width of the connecting surface is W2, then P = W1 + W2, and in this embodiment, W2 ≥ 0. That is, when viewed from the front direction of the screen, the reflecting surfaces 13 are arranged with gaps in the arrangement direction.

[0027] 2, 3, etc. show an example in which the arrangement pitch P, angle θ1, etc. of the reflecting surfaces 13 are constant in the arrangement direction of the reflecting surfaces 13 (unit optical shapes 121a). However, in this embodiment, although the arrangement pitch P of the reflecting surfaces 13 is actually constant, the angle θ2 gradually increases and the angle θ1 gradually decreases with increasing distance from point C in the arrangement direction. The angle θ1, the arrangement pitch P, etc. may be set appropriately depending on the projection angle of the image light from the image source LS (the incident angle of the image light onto the screen 10), the size of the pixels of the image source LS, the screen size of the screen 10, the refractive index of each layer, etc. For example, the arrangement pitch P may be changed along the arrangement direction of the reflecting surfaces 13.

[0028] The reflective performance of the reflective surface 13 and the means for reflecting the image light on the reflective surface 13 (i.e., the means for providing the reflective surface 13) can be selected depending on the desired usage environment of the screen 10 and the desired optical performance, etc. For example, the reflective surface 13 may be provided by forming a low-refractive index layer on the first surface 121b, the low-refractive index layer being made of a material with high optical transparency and a lower refractive index than the resin layer 12 (first resin layer 121, second resin layer 122), to take advantage of the difference in refractive index between the resin layer 12 and the low-refractive index layer. Such a low-refractive index layer is formed, for example, by vapor deposition or sputtering of a metal fluoride such as magnesium fluoride (MgF2) or aluminum fluoride (AlF3), silicon oxide (SiO2), a silicon-based resin, or the like. In this case, the refractive index of the low-refractive index layer is preferably approximately 1.35 to 1.45.

[0029] When the reflective surface 13 is provided by the difference in refractive index between the low refractive index layer and the resin layer 12, light incident on the reflective surface 13 at an incident angle equal to or greater than the critical angle is totally reflected, and most of the light incident at an incident angle less than the critical angle is transmitted through the reflective surface 13. Such a low refractive index layer preferably has a thickness sufficient to totally reflect the image light at the interface K1.

[0030] Furthermore, when the reflective surface 13 is provided by the difference in refractive index between the low refractive index layer and the resin layer 12, the resin layer 12 is preferably formed using an ultraviolet-curable resin that has high light transmittance and a higher refractive index than general ultraviolet-curable resins, such as an epoxy acrylate-based ultraviolet-curable resin, a urethane-based ultraviolet-curable resin with a metal oxide added thereto to increase the refractive index, or an ultraviolet-curable resin with titanium oxide (TiO2) added thereto to increase the refractive index. In this case, the refractive index of the resin layer 12 is preferably about 1.56 to 1.7.

[0031] The reflecting surface 13 may be provided by forming a semi-transmissive reflective layer (a so-called half mirror) on the first surface 121b, which reflects part of the incident light and transmits part of it. Such a semi-transmissive reflective layer may be formed by vapor deposition of a highly light-reflective metal, such as aluminum, silver, nickel, or chromium, or by sputtering the above-mentioned highly light-reflective metal, transferring a metal foil, or applying a paint containing a thin metal film. Furthermore, such a semi-transmissive reflective layer may be formed by vapor deposition of a dielectric multilayer film or a dielectric single-layer film that has high transparency, small light absorption loss, and can achieve high reflectance.

[0032] When the reflective surface 13 is provided by forming a semi-transmissive reflective layer as described above on the first surface 121b, at least a portion of the image light incident on the reflective surface 13 is reflected and at least a portion of the image light is transmitted through the reflective surface 13. The reflectance and transmittance of such a semi-transmissive reflective layer can be appropriately set according to the desired optical performance. From the viewpoint of favorably reflecting image light and favorably transmitting light other than image light (for example, light from the outside, such as sunlight), it is desirable that the transmittance be approximately 30 to 80% and the reflectance be approximately 5 to 60%.

[0033] Furthermore, when the reflective surface 13 is provided using a semi-transparent reflective layer, the resin layer 12 is preferably formed from an ultraviolet-curable resin having high light transmittance, such as a urethane acrylate, polyester acrylate, epoxy acrylate, polyether acrylate, polythiol, or butadiene acrylate. The semi-transmissive reflective layer may have an extremely low transmittance depending on the environment in which the screen 10 is used, etc. Such a reflective layer with low transmittance can be formed by using the same material as the semi-transmissive reflective layer described above and adjusting the transmittance to a low level by increasing the thickness, etc.

[0034] The image light deflection section 10A of this embodiment is formed, for example, by the following method. First, a first resin layer 121 having unit optical shapes 121a arranged on the light-emitting surface of the first base layer 11 is formed by UV molding or the like. Then, a low refractive index layer or a semi-transmissive reflective layer as described above is formed on the first surface 121b of the unit optical shapes 121a by vapor deposition or the like, thereby imparting a reflective function to the first surface 121b and providing the reflective surface 13. After forming the reflective surface 13, a material for forming the second resin layer 122 is laminated and cured to fill in the irregularities of the unit optical shapes 121a and flatten the surface, thereby forming the second resin layer 122. As a result, the reflective surface 13 is formed inside the resin layer 12.

[0035] In this way, the transparency of the screen 10 is improved by positioning the reflective surface 13 inside the resin layer 12. In this embodiment, it is desirable that the refractive index of the second resin layer 122 is equal to or approximately equal to the refractive index of the first resin layer 121 (the difference in refractive index is small enough to be considered equal), from the viewpoint of improving the transparency of the screen 10. Note that although the second resin layer 122 has the same refractive index as the first resin layer 121, it may be formed from a different resin. Furthermore, by providing the reflecting surface 13 inside the resin layer 12, the reflecting surface 13 can be protected. Furthermore, since the first resin layer 121 and the second resin layer 122 are connected at the connection surface (second surface 121c), the second resin layer 122 is less likely to peel off.

[0036] Here, the state of the image light incident on the image light deflection unit 10A of this embodiment will be described. Fig. 5 is a diagram illustrating the image light incident on the image light deflection unit 10A of the first embodiment. Fig. 5 shows the same cross section as the above-mentioned Fig. 3. To facilitate understanding, Fig. 5 and the related description will be described taking as an example a case where the image light La, Ld is not affected by the image light diffusion unit 10B (light control layer 16) located closer to the light entrance side than the image light deflection unit 10A. As shown in FIG. 5, the image light La projected from the image source LS and incident on the image light deflection unit 10A from the light incident side (−Z side) is incident on the reflecting surface 13.

[0037] When a reflective surface 13 is provided due to the difference in refractive index between the low refractive index layer and the resin layer 12, the image light La is incident on the reflective surface 13 at an incident angle greater than the critical angle, is totally reflected, and is emitted in a direction where the image can be viewed by an observer O1 (see Figure 1) located directly in front of the light exit side (+Z side) of the screen 10 (image light Lb). Furthermore, when the reflective surface 13 is provided by forming a semi-transmissive reflective layer, part of the image light La is reflected by the reflective surface 13 and emitted in a direction where the image can be viewed by an observer O1 (see FIG. 1) positioned in front of the light-emitting side (+Z side) of the screen 10 (image light Lb), and part of the image light La is transmitted through the reflective surface 13 and travels upward toward the light-emitting side of the screen 10 (image light Lc indicated by a dashed line in FIG. 5). Most of this image light Lc is emitted outside the range visible to the observer O1. Note that if the transmittance of the semi-transmissive reflective layer is extremely low, the amount of image light Lc will be extremely small. Furthermore, a portion of the image light Ld does not enter the reflecting surface 13 but travels upward toward the light exit side of the screen 10.

[0038] 2, the second base layer 15 is a light-transmitting layer formed on the light-emitting side (+Z side) of the resin layer 12. The second base layer 15 has a function of protecting the light-emitting side of the screen 10. A sheet-like member made of a resin having high light transmittance is used for the second base layer 15. For example, the second base layer 15 may be a sheet-like member formed using the same material as the first base layer 11 described above. When the second base layer 15 is located on the light-emitting side (+Z side) of the screen 10 as in this embodiment, the second base layer 15 may have a hard coat function, an antifouling function, an antistatic function, etc.

[0039] The bonding layer 17 is a layer that functions to integrally bond the light control layer 16 and the first base material layer 11. The bonding layer 17 can be made of an adhesive or sticky material that has high light transparency. The light control layer 16 is a layer located on the light incident side (image source side, -Z side) in the thickness direction (Z direction) of the first base material layer 11. In this embodiment, the light control layer 16 is provided integrally with the first base material layer 11 on the light incident side (image source side) via a bonding layer 17.

[0040] The light control layer 16 corresponds to the image light diffusion section 10B and is a section that selectively diffuses image light. The light control layer 16 has a greater diffusion effect on light incident from a specific angle range than on light incident from other angle ranges. This specific angle range is an angle range in which light is incident obliquely onto the light control layer 16 at an angle greater than or near 0° relative to the normal to the light entrance surface (a surface parallel to the screen surface) of the light control layer 16. In other words, the light control layer 16 has the function of diffusing and transmitting obliquely incident light to a greater extent than light incident at an incident angle of 0°. The specific angle range in which the light control layer 16 exhibits a diffusing effect can be appropriately set depending on the position of the image source LS relative to the screen 10, i.e., the incident angle of the main image light, etc.

[0041] Fig. 6 is a diagram illustrating the light control effect of the light control layer 16. Fig. 6 shows a cross section parallel to the vertical direction (Y direction) of the screen and the thickness direction (Z direction) of the light control layer 16. In Fig. 6, the light incident side (image source side, -Z side) and light exit side (observer side, +Z side) surfaces of the light control layer 16 are parallel to the screen surface (XY plane), and the dashed line H is a line perpendicular to the light incident side surface and the light exit side surface of the light control layer 16.

[0042] 6, the light control layer 16 has the function of diffusing light incident from air on the light entrance side (-Z side) at an incident angle within a first incident angle range R1 and emitting it to the light exit side (+Z side), and transmitting light incident at an incident angle within a second incident angle range R2, which is an incident angle outside the first incident angle range R1, to the light exit side without diffusing or slightly diffusing the light. In the light control layer 16, the degree of diffusion of light incident at an incident angle within the second incident angle range R2 is significantly smaller than the degree of diffusion of light incident at an incident angle within the angle range of the first incident angle range R1. 5, the light control layer 16 has the function of diffusing light incident from the air on the light output side (+Z side) at an incident angle within the third incident angle range R3 and outputting it to the light input side (-Z side), and diffusing or slightly diffusing light incident at an incident angle within a fourth incident angle range R4, which is an incident angle outside the third incident angle range R3, and transmitting it to the light input side. In the light control layer 16, the degree of diffusion for light incident at an incident angle within the fourth incident angle range R4 is significantly smaller than the degree of diffusion for light incident at an incident angle within the third incident angle range R3.

[0043] The first incident angle range R1 includes the main incident angle range of the image light L that is projected from the image source LS and enters the screen 10 (light control layer 16). In this embodiment, the first incident angle range R1 is a range on the light incident side (image source side, -Z side) that is 25° to 55° below (to the -Y side) the line H. The second incident angle range R2 is an angle other than the first incident angle range R1 on the light incident side of the light control layer 16. In this embodiment, the third incident angle range R3 is a range on the light output side (+Z side) that is 25° or more and 55° or less on the upper side (+Y side) with respect to the line H. The fourth incident angle range R4 is an angle other than the third incident angle range R3 on the light output side of the light control layer 16.

[0044] Therefore, at any point on the surface of the light-input side (-Z side), the light control layer 16 selectively diffuses and transmits light that is incident from the lower side (-Y side) in the vertical direction of the screen at an incident angle of 25° or more and 55° or less, and transmits light that is incident from other angular ranges to the light-output side (+Z side) without diffusing it or diffusing it at a level significantly weaker than the above-mentioned angular range. Also, at any point on the surface of the light-output side, the light control layer 16 selectively diffuses and transmits light that is incident from the upper side (+Y side) in the vertical direction of the screen at an incident angle of 25° or more and 55° or less, and transmits light that is incident from other angular ranges to the light-input side without diffusing it or diffusing it at a level significantly weaker than the above-mentioned angular range.

[0045] The haze value (diffuse transmittance) of light that enters the light control layer 16 from the light entrance side at an incident angle within the first incident angle range R1 and exits to the light exit side is greater than the haze value (diffuse transmittance) of light that enters the light control layer 16 from the light entrance side (-Z side) at an incident angle within the second incident angle range R2 (particularly, an incident angle of 0°) and exits to the light exit side. Similarly, the haze value of light that enters the light control layer 16 from the light exit side at an incident angle within the third incident angle range R3 and exits to the light entry side is greater than the haze value of light that enters the light control layer 16 at an incident angle within the fourth incident angle range R4 (particularly, an incident angle of 0°) and exits to the light exit side. The haze value is expressed as the ratio of the diffuse transmittance to the total light transmittance, and means the diffusion rate of transmitted light. The haze value of the light control layer 16 can be measured using a haze meter (for example, HM-150 manufactured by Murakami Color Research Laboratory).

[0046] For incident light within the first incident angle range R1 and the third incident angle range R3, since the first incident angle range R1 and the third incident angle range R3 in this embodiment are 25° or more and 55° or less, the assumed incident angle is set to 40°, and the transmittance when light is incident at this angle is defined as the total light transmittance, and the proportion of light that is diffused by 2.5° or more to the light that is incident at this assumed incident angle, travels straight through the light control layer 16, and is transmitted through and emerges is defined as the diffuse transmittance. The haze value (diffuse transmittance) of light that enters the light control layer 16 from the light entrance side (-Z side) at an incident angle of 0° within the second incident angle range R2 and exits to the light exit side (+Z side) is preferably low, ideally 0%. Similarly, the haze value of light that enters the light control layer 16 at an incident angle of 0°, which is an incident angle within the fourth incident angle range R4, is also preferably low, ideally 0%.

[0047] A suitable example of such a light control layer 16 is a visibility control film (for example, visibility control film Y-2555 manufactured by Lintec Corporation) formed by laminating multiple layers of transparent resin with different refractive indices in a predetermined direction at a predetermined thickness, and changing the direction of ultraviolet light irradiation when curing each layer.

[0048] Fig. 7 is a diagram showing an example of image light and external light incident on the screen 10 of the first embodiment. Fig. 7 shows an enlarged view of a portion of a cross section similar to the cross section of the screen 10 shown in Fig. 2. In order to facilitate understanding, Fig. 7 and the description thereof will be described assuming that there is no difference in refractive index at the interface between the light control layer 16 and the bonding layer 17, the interface between the bonding layer 17 and the first base material layer 11, the interface between the first base material layer 11 and the resin layer 12, and the interface between the resin layer 12 and the second base material layer 15. The image light L11 projected from the image source LS located below the screen 10 is incident on the light control layer 16 at an incident angle within the first incident angle range R1, is diffused, passes through the bonding layer 17 and the first base material layer 11, and is incident on the resin layer 12.

[0049] The image light L11 is then reflected (including total reflection) by the reflecting surface 13 and emitted toward the observer O1 located in front of the light-emitting side (+Z side) of the screen 10. This allows the screen 10 to display a bright, clear image with a sufficient viewing angle for the observer O1 located in front of the light-emitting side. Note that, although not shown, if the reflecting surface 13 is provided by forming a semi-transmissive reflective layer, part of the image light L11 passes through the reflecting surface 13 and heads upward toward the light-emitting side of the screen 10 (see image light Lc in FIG. 4). Furthermore, when the image light L11 enters the screen 10 from the light-entering side, a portion of the image light L11 (not shown) is reflected by the light-entering surface of the screen 10 and travels upward, but such light hardly reaches the observer O2 located directly in front of the light-entering side of the screen 10.

[0050] Furthermore, of the image light incident on the screen 10, a portion of the image light L12 passes through the resin layer 12 and the second base material layer 15 without entering the reflective surface 13 and is emitted upward on the light-emitting side of the screen 10. Almost none of this image light L12 reaches the viewer O1 positioned directly in front of the light-emitting side of the screen 10. In this embodiment, the image light is projected from below the screen 10, and the angle θ1 (see Figures 3, 5, etc.) that the reflective surface 13 makes with a plane parallel to the screen surface is larger than the angle of incidence of the image light at each point in the vertical direction of the screen 10. Therefore, very little image light directly enters the reflective surface 13 from the opposite side to the image source LS (upper side in the vertical direction of the screen) along the arrangement direction of the reflective surface 13, and the image light that enters from that direction and is reflected by the reflective surface 13 is hardly visible to the observer O2 on the light incident side.

[0051] Next, light from the outside, such as sunlight or illumination light (hereinafter referred to as external light), other than image light, which enters the screen 10 from above the light entrance side (-Z side) or light exit side (+Z side) will be described. Of the external light G11, G12, and G13 incident on the screen 10, a portion of the external light (not shown) is reflected by the surface on the light-entering side and the surface on the light-exiting side of the screen 10 and travels downwards on the screen 10, respectively.

[0052] External light G11 incident on the screen 10 from above on the light entrance side (-Z side) enters the light control layer 16 from the light entrance side at an incident angle within the second incident angle range R2, so it passes through the light control layer 16 without being diffused and travels inside the screen 10 toward the light exit side (+Z side). Then, the external light G11 is incident on the reflecting surface 13 within the resin layer 12.

[0053] When the reflective surface 13 is provided by the difference in refractive index between the low refractive index layer and the resin layer 12, external light G11 is incident on the reflective surface 13 at an angle of incidence less than the critical angle, and most of the external light G11 is transmitted through the reflective surface 13 and travels downward toward the light-emitting side inside the screen 10 (external light G11a). The external light G11a may be emitted downward toward the light-emitting side of the screen 10, or may be totally reflected by the surface of the light-emitting side of the screen 10 and travel further downward inside the screen 10, where it is gradually attenuated. Furthermore, when the reflective surface 13 is provided by a semi-transparent reflective layer, part of the external light G11 incident on the reflective surface 13 passes through the reflective surface 13 and travels downward on the light exit side of the screen 10 (external light G11a), and part of the external light G11 is reflected by the reflective surface 13 and travels upward on the light entrance side of the screen 10 (external light G11b).

[0054] Furthermore, external light G12 that has entered the screen 10 from above on the light entrance side (-Z side) is incident from the light entrance side to the light control layer 16 at an incident angle within the second incident angle range R2, and therefore passes through the light control layer 16 without being diffused and proceeds inside the screen 10 towards the light exit side, passes through the resin layer 12 without entering the reflective surface 13, and proceeds inside the screen 10 towards the light exit side downward. This external light G12 may be emitted towards the light exit side downward of the screen 10, or be totally reflected by the surface of the light exit side of the screen 10 and proceed further downward inside the screen 10, where it is gradually attenuated.

[0055] External light G13 incident on the screen 10 from above on the light-exiting side (+Z side) passes through the second base material layer 15, passes through the resin layer 12 without entering the reflective surface 13, and travels downward toward the light-incident side inside the screen 10. The external light G13 may be emitted downward toward the light-incident side of the screen 10, or may be totally reflected by the surface of the light-incident side of the screen 10 and travel further downward inside the screen 10, where it is gradually attenuated. As described above, most of the external light that enters the screen 10 from above the light-entering side or light-exiting side is directed downward toward the light-exiting side or light-entering side of the screen 10, and the amount of light that reaches the observers O1 and O2 is significantly small. Therefore, the screen 10 can suppress a decrease in image contrast caused by external light.

[0056] Furthermore, external light G14 and G15 incident on the screen 10 at a small incident angle, such as an incident angle of 0°, enters the screen 10 and exits to the light entrance side and light exit side, respectively, without entering the reflective surface 13. In this embodiment, external light G15 enters the light control layer 16 from the light entrance side at an incident angle within the second incident angle range R2, and external light G14 enters the light control layer 16 from the light exit side at an incident angle corresponding to an angle within the fourth incident angle range R4. Therefore, external light G14 and G15 are transmitted through the screen 10 without being diffused by the light control layer 16. In addition, some of the external light (not shown) that enters the screen 10 at a small angle of incidence, such as 0°, is incident on the reflective surface 13 and reflected, but the amount of light is significantly smaller than that of the external light G14 and G15, so it has little effect on the contrast of the image or the transparency of the screen 10.

[0057] From the above, when observers O2 and O1 observe the scenery on the other side of screen 10 through screen 10 from the light entrance side (-Z side) and the light exit side (+Z side), the scenery on the other side of screen 10 can be observed with high transparency without being blurred or white-out, and screen 10 can exhibit high transparency.

[0058] In a transmissive screen that is provided with a light diffusion layer containing a diffusing material such as particles that diffuse light, but does not have an image light deflection unit 10A, increasing the diffusion strength of the light diffusion layer can brighten the image displayed on the screen, but this can also reduce the contrast of the image or cause unnecessary external light to be diffused, reducing transparency and making the background image observed through the screen appear cloudy and whitish. Furthermore, when projecting an image from the front onto such a transmission screen, if an attempt is made to maintain high transparency by reducing the diffusion intensity, the image light will reach the viewer without diffusing. For this reason, a method is used in which the image light is projected obliquely from below the screen, but in this case, most of the image light is diffused obliquely upward from the screen, making the image dark and difficult for the viewer to view.

[0059] In contrast, according to the screen 10 of this embodiment, the image light is diffused by the light control layer 16 (image light diffusion section 10B) and then deflected toward the observer O1 by the image light deflection section 10A, so that a bright image can be displayed to the observer O1 with a sufficient viewing angle. Furthermore, the screen 10 selectively diffuses most of the image light incident from an oblique direction by the light control layer 16 (image light diffusion portion 10B), while most of the external light passes through the screen 10 without being diffused or exits outside the range visible to the observers O1 and O2. Therefore, according to this embodiment, the transparency of the screen 10 can be maintained and a decrease in image contrast due to the diffusion of external light can be significantly suppressed. As described above, according to this embodiment, it is possible to display bright and clear images while maintaining the transparency of the screen 10.

[0060] Furthermore, according to this embodiment, the reflective surfaces 13 are arranged concentrically about a point C located outside the display area (screen) of the screen 10 and on the lower side (image source side) in the vertical direction of the screen. Therefore, even with image light projected at a large angle from a short-focus image source LS located outside the display area of ​​the screen 10 and on the lower side in the vertical direction of the screen, the image does not become dark in the horizontal direction of the screen, and a good image with high surface uniformity of brightness can be displayed.

[0061] (Second embodiment) FIG. 8 is a diagram illustrating an image light deflection unit 20A according to the second embodiment. As with Figure 2 of the first embodiment described above, Figure 8 shows an enlarged portion of a cross section that passes through the center of the screen (the geometric center of the screen) of screen 10 (a point corresponding to point A shown in Figure 1), is parallel to the vertical direction of the screen (Y direction), and is perpendicular to the screen surface (parallel to the Z direction). The image light deflection unit 20A of the second embodiment is the same as the image light deflection unit 10A shown in the first embodiment, except for the means for providing the reflecting surface 13 and the shape of the unit optical shapes 221a. Therefore, in the following description, parts that perform the same functions as in the first embodiment described above are denoted by the same reference numerals or with the same reference numerals at the end, and duplicated description will be omitted as appropriate. The image light deflection section 20A of the second embodiment can be applied to the screen 10 and the image display device 1 in place of the image light deflection section 10A of the first embodiment.

[0062] The image light deflection unit 20A of this embodiment includes a plurality of reflective surfaces 13 arranged inside the resin layer 22. The refractive index of the first resin layer 221 of the resin layer 22 is smaller than the refractive index of the second resin layer 222, and a part of the interface between the first resin layer 221 and the second resin layer 222 serves as the reflective surface 13 that reflects the image light and changes its direction. 8, the first resin layer 221 has a plurality of unit optical shapes 221a arranged on the light-emitting side. Each unit optical shape 221a has a trapezoidal cross section that is convex toward the light-emitting side, and has a top surface 221d located on the light-emitting side, a first surface 221b located below the top surface 221d, and a second surface 221c located above the top surface 221d. In FIG. 8, for ease of understanding, the first surface 221b, the top surface 221d, and the second surface 221c are shown with dashed lines, but in reality, it is difficult to visually identify each surface.

[0063] The unit optical shapes 221a of this embodiment are arranged in the left-right direction of the screen (X direction) as the longitudinal direction, along a plane parallel to the screen surface in the up-down direction of the screen (Y direction), with an arrangement pitch of P. The first surface 221b is inclined so that its light-entering side (-Z side) end is located closer to the image source LS (lower in the up-down direction of the screen) in the arrangement direction of the unit optical shapes 221a (reflecting surfaces 13) than its light-exiting side (+Z side) end. The first surface 221b forms an angle θ1 with a plane parallel to the screen surface. As in the first embodiment, this angle θ1 is preferably 70° or greater. In this embodiment, an example will be described in which the angle θ1 is constant in the arrangement direction of the unit optical shapes 221a (reflecting surfaces 13). Note that the angle θ1 may be gradually reduced as the distance from the image source LS increases along the arrangement direction of the unit optical shapes 221a (toward the upper side in the vertical direction of the screen).

[0064] The second surface 221c is a surface facing the first surface 221b in the arrangement direction of the unit optical shapes 221a, and forms an angle θ2 with respect to a plane parallel to the screen surface. The second surface 221c is inclined in the opposite direction to the first surface 221b, that is, in the unit optical shapes 221a, the end on the light output side (+Z side) is located closer to the image source LS (lower in the screen vertical direction) than the end on the light input side (-Z side). The top surface 221d is the surface located closest to the light output surface side of the unit optical shapes 221a between the first surface 221b and the second surface 221c in the arrangement direction of the unit optical shapes 221a.

[0065] In this embodiment, the second surface 221c is orthogonal to a plane parallel to the screen surface (θ2=90°), and the top surface 221d is a surface parallel to the screen surface (XY plane). By configuring the second surface 221c and the top surface 221d in this manner, the transparency of the screen 10 can be maintained at a high level. Note that, from the viewpoints of maintaining transparency and suppressing stray light, it is preferable that the angle θ2 be 90° or an angle close to 90°.

[0066] Similar to the unit optical shapes 121a of the first embodiment described above, the unit optical shapes 221a may be arranged concentrically around a point C (see FIG. 4) located outside the display area of ​​the screen 10. In this case, the angle θ1 may be gradually reduced as the distance from the point C increases in the arrangement direction of the unit optical shapes 221a.

[0067] In this embodiment, the first resin layer 221 and the second resin layer 222 have different refractive indices, with the first resin layer 221 having a smaller refractive index than the second resin layer 222. Due to the difference in refractive index between the first resin layer 221 and the second resin layer 222, the first surface 221b serves as a reflective surface 13 that reflects at least a portion of the image light. In such an image light deflection unit 20A, as shown in Figure 8, a portion of the image light (image light Lg) passes through the second surface 221c and enters the second resin layer 222, then enters the reflecting surface 13 (first surface 221b) at an angle greater than or equal to the critical angle, is totally reflected, and travels toward the observer O1 on the light output side. Even when the image light deflection unit 20A as in this embodiment is used, the image light can be sufficiently directed toward the observer O1, and the screen 10 and image display device 1 can have sufficient transparency and display bright, high-quality images.

[0068] (Third embodiment) FIG. 9 is a diagram showing the layer structure of a screen 30 according to the third embodiment. As with Figure 2 of the first embodiment described above, Figure 9 shows an enlarged portion of a cross section that passes through the center of the screen (the geometric center of the screen) of screen 10 (a point corresponding to point A shown in Figure 1), is parallel to the vertical direction of the screen (Y direction), and is perpendicular to the screen surface (parallel to the Z direction). The screen 30 of the third embodiment differs from the screen 10 shown in the first embodiment in that a light diffusion layer 38 containing a diffusing material is arranged as an image light diffusion section 30B on the light output side (+Z side) of the image light deflection section 10A, but the screen 30 has the same configuration as the screen 10 of the first embodiment. Therefore, in the following description, parts that perform the same functions as those in the first embodiment are designated with the same reference numerals or with the same reference numerals at the end, and duplicate descriptions will be omitted as appropriate.

[0069] As shown in Figure 9, the screen 30 of the third embodiment has, in the thickness direction (Z direction) of the screen 30, a first base material layer 11, a resin layer 12, a reflective surface 13, a second base material layer 15, a bonding layer 37, and a light diffusion layer 38, in that order from the light incident side (image source side, -Z side). In the screen 30, the image light diffusion section 30B is a light diffusion layer 38, and the image light deflection section 10A is a resin layer 12 and a reflective surface 13. This screen 30 can be applied to the image display device 1 in place of the screen 10 of the first embodiment.

[0070] The bonding layer 37 is a layer having a function of integrally bonding the second base material layer 15 and the light diffusion layer 38. As with the bonding layer 17 of the first embodiment described above, the bonding layer 37 can be made of an adhesive or pressure-sensitive adhesive having high light transmittance. The light diffusion layer 38 is a layer in which a particulate diffusing material is mixed into a resin having high light transmittance as a base material. A known diffusion layer or diffusion sheet can be used as the light diffusion layer 38. The haze value and other properties of the light diffusion layer 38 can be set as appropriate, and the diffusion characteristics may be omnidirectional or anisotropic. In addition, in this embodiment, an example is shown in which the image light diffusion section 30B consisting of the light diffusion layer 38 is positioned on the light output side (+Z side) of the image light deflection section 10A, but this is not limited to this, and it may also be positioned on the light input side (-Z side) of the image light deflection section 10A.

[0071] Even with the screen 30 including the image light diffusion section 30B of this embodiment, it is possible to display a bright and clear image. Moreover, even with the screen 30 including the image light diffusion section 30B of this embodiment, it is possible to achieve a level of transparency sufficient for use.

[0072] (Variations) The present invention is not limited to the above-described embodiments, and various modifications and variations are possible, and these are also within the scope of the present invention.

[0073] (1) In the first embodiment, the image light deflection unit 10A may be configured such that the layer that forms the reflecting surface 13 is also formed on the connecting surface (second surface 121c). Fig. 10 is a diagram illustrating a modified image light deflection unit 60A. Fig. 10 shows a cross section of the image light deflection unit 60A corresponding to the cross section of the image light deflection unit 10A shown in Fig. 3. This image light deflection unit 60A has a configuration in which a first resin layer 121, a reflective surface forming layer 130, and a second resin layer 122 are laminated in the thickness direction. When the reflection surface-forming layer 130 is a low refractive index layer, even in this configuration, the image light is incident on the reflection surface-forming layer 130 (layer 132 shown in FIG. 10) on the second surface 121c at an angle less than the critical angle, passes through, and is totally reflected by the reflection surface-forming layer 130 (layer 131 shown in FIG. 10, which is the portion that forms the reflection surface 13 in this configuration) on the first surface 121b, and travels toward the viewer (image light Le). Therefore, this type of image light deflection unit 60A can also be used as a transmission screen similar to the screen 10 of the first embodiment described above.

[0074] Furthermore, when the reflective surface 13 is formed by a semi-transmissive reflective layer and its transmittance is small, the angle θ2 that the second surface 121c makes with a plane parallel to the screen surface can be appropriately set in accordance with the position of the image source LS, etc., so that part of the image light is reflected by the reflective surface forming layer 130 (layer 132, the part that forms the reflective surface 13 in this form) on the second surface 121c and directed toward the front of the light incident side (image light Lf shown by the dashed line in Figure 10), thereby making it possible to create a transparent reflective screen.

[0075] Furthermore, when the reflective surface 13 is formed by a semi-transmissive reflective layer, by adjusting the reflectance and transmittance of the reflective surface forming layer 130 (layer 131) on the first surface 121b and the reflective surface forming layer 130 (layer 132) on the second surface 121c, a portion of the image light can be reflected by the reflective surface forming layer 130 (layer 132) on the second surface 121c and directed toward the front of the light incident side (image light Lf shown by the dashed line in Figure 10), and a portion of the image light can be reflected by the reflective surface forming layer 130 (layer 131) on the first surface 121b and directed toward the observer on the light output side (image light Le). This allows a transparent screen that can display images on both sides. In this case, it is preferable to provide an image light diffusion unit 30B, as shown in the third embodiment, on the light exit side of the image light deflection unit 10A in addition to the image light diffusion unit 10B on the light entrance side.

[0076] When a double-sided display screen is used, the angle θ1 is set so that the image light Le reflected by the reflecting surface-forming layer 130 (layer 131) on the first surface 121b is directed in the front direction of the light exit side, and the angle θ2 is set so that the image light (image light Lf) reflected by the reflecting surface-forming layer 130 (layer 132) on the second surface 121c is directed in the front direction of the light entrance side. From the viewpoint of displaying good images to viewers positioned in front of the light exit side and the light entrance side, the apex angle θ3 of the unit optical shape 121a is preferably close to 90°, and more preferably 90°.

[0077] (2) In the first and third embodiments, the reflecting surface 13 in a cross section parallel to the arrangement direction of the unit optical shapes 121a and the thickness direction of the screens 10 and 30 may be curved. Fig. 11 is a diagram illustrating a modified image light deflection unit 70A. Fig. 11 shows a cross section of the image light deflection unit 70A that corresponds to the cross section of the image light deflection unit 10A shown in Fig. 3. When the reflective surface 13 has a gently curved shape in the cross section shown in Fig. 11, the angle θ1 that the reflective surface 13 makes with a direction parallel to the screen surface (XY plane) corresponds to the angle that a straight line passing through point t1, which is the light-emitting side end of the reflective surface 13, and point t2, which is the light-incident side end of the reflective surface 13, makes with a plane parallel to the screen surface.

[0078] (3) In the first embodiment, the shape of the unit optical shape 121a may be changed as appropriate. 12A to 12C are diagrams illustrating a modified image light deflection section 80A. Figures 12A to 12C show a cross section of the image light deflection section 80A, which corresponds to the cross section of the image light deflection section 10A shown in Figure 3. In the modified image light deflection section 80A, a plurality of reflective surfaces 13 are arranged in a resin layer 82. The resin layer 82 includes a first resin layer 821 and a second resin layer 822. 12(a), the cross-sectional shape of each unit optical shape 821a in the arrangement direction and the thickness direction of the screen may be a triangular shape that is convex toward the light-emitting side, and a gap 821e of a predetermined size may be provided between adjacent unit optical shapes 821a. In this case, each unit optical shape 821a has a first surface 821b and a second surface 821c, and the reflecting surface 13 is provided on the first surface 821b. It is preferable that the gap 821e is parallel to the screen surface and the second surface 821c is perpendicular or at an angle close to perpendicular to a plane parallel to the screen surface, since this maintains the transparency of the screen and prevents the layer forming the reflective surface 13 from being formed in unintended locations such as the second surface 821c when it is vapor-deposited on the first surface 821b, without the need for masking or the like.

[0079] Also, as shown in Figure 12(b), the unit optical shape 821a may have a triangular shape similar to the shape shown in Figure 12(a), a reflecting surface 13 may be provided on the first surface 821b, there may be no gap 821e, and adjacent unit optical shapes 821a may be adjacent to each other. In this case, it is preferable that the second surface 821c is perpendicular to a plane parallel to the screen surface (angle θ2 = 90°) or forms an angle close to perpendicular, because this prevents the layer forming the reflective surface 13 from being formed in unintended locations such as the second surface 821c when it is vapor-deposited on the first surface 821b, without the need for masking or the like. 12(b), when viewed from the normal direction of the screen surface, there are no gaps in the arrangement direction of the reflective surfaces 13, but it is possible to maintain a usable level of transparency of the screen by adjusting the transmittance, etc., of the layers that form the reflective surfaces 13. Furthermore, without being limited to this, it is also possible to adjust the angle θ2 so that there are gaps between the reflective surfaces 13 when viewed from the normal direction of the screen surface.

[0080] 12(c), the cross-sectional shape of each unit optical shape 821a in the arrangement direction and the thickness direction of the screen may be a trapezoid convex toward the light-emitting side as shown in the second embodiment, and may have a top surface 821d, a first surface 821b, and a second surface 821c. The top surface 821d is parallel to the screen surface, and the second surface 821c is orthogonal (θ2=90°) or forms an angle close to orthogonal with respect to a plane parallel to the screen surface, which is preferable because this maintains the transparency of the screen and prevents the layer forming the reflective surface 13 from being formed in unintended locations such as the second surface 821c without the need for masking or the like when depositing the layer on the first surface 821b. 12(c), the layer forming reflective surface 13 may be formed on at least a part of top surface 821d in addition to first surface 821b. In particular, when reflective surface 13 is provided by the refractive index difference between a low refractive index layer and resin layer 82, a low refractive index layer may be formed on at least a part of top surface 821d and second surface 821c in addition to first surface 821b. Even in such configurations, the transmittance required for the screen can be maintained.

[0081] 12(c), the second surface 821c and the top surface 821d are L-shaped, and the first resin layer 821 and the second resin layer 822 are connected in the portion where the layer that forms the reflective surface 13 is not formed, which makes it difficult for the second resin layer 822 to peel off. Note that in the form shown in Fig. 12(a) described above, the second surface 821c and the gap 821e are L-shaped, which similarly provides the effect of suppressing the peeling off of the second resin layer 822.

[0082] Furthermore, in Figure 12(c), the second surface 821c is shown as being perpendicular or at an angle close to perpendicular to a plane parallel to the screen surface, but this is not limited thereto, and the second surface 821c may be angled with respect to a direction perpendicular to the screen surface in the cross section shown in Figure 12(c), and may be inclined in the opposite direction to the inclination direction of the first surface 821b. Furthermore, in the case of the image light deflection unit 80A shown in Figures 12(a) to (c), a good image can be viewed even if the image light diffusion unit 30B shown in the third embodiment is placed on the light output side of this image light deflection unit 80A as the image light diffusion unit.

[0083] (4) In each embodiment, the reflective surface 13 may be a rough surface having fine irregular concaves and convexes. By using such a shape, light incident on the reflective surface 13 is diffusely reflected. This allows the viewing angle of the image to be widened. In addition, in this case, if the reflective surface 13 is formed of a semi-transmissive reflective layer, a part of the light incident on the reflective surface 13 is transmitted without being diffused, thereby maintaining transparency. In addition, if the reflective surface 13 is provided with a low refractive index layer, light incident at an angle less than the critical angle is transmitted without being diffused, thereby maintaining transparency.

[0084] Furthermore, by adopting such a shape, it is possible to reduce unpleasant glare (so-called speckle, also known as scintillation) and color unevenness in the image. As shown in the above-mentioned modified form (1), when the reflective surface forming layer 130 is also provided on the connecting surface (second surface 121c), the reflective surface forming layer 130 on the connecting surface may also have a fine and irregular uneven shape on its surface depending on the desired performance of the screen.

[0085] (5) In the first embodiment, the light control layer 16 may be configured to transmit light incident from the light output side (+Z side) without diffusing it, regardless of the incident angle. In other words, the light control layer 16 may be configured not to have the third incident angle range R3.

[0086] (6) In the first embodiment, an example has been described in which the light control layer 16 selectively diffuses incident light in a cross section parallel to the vertical direction and thickness direction of the screen depending on the angle of incidence in the vertical direction of the screen. However, this is not limiting, and the light control layer 16 may be configured to selectively diffuse incident light in a cross section parallel to the arrangement direction and thickness direction of the reflective surfaces 13 depending on the angle of incidence in the arrangement direction of the reflective surfaces 13. When the reflective surfaces 13 are arranged concentrically about point C as in the first embodiment, the optical performance of the light control layer 16 can be made to have a characteristic of being distributed concentrically about point C, thereby making it possible to diffuse light more effectively and ensure a sufficient viewing angle in areas where the viewing angle is likely to be reduced, such as the left and right ends of the upper side of the screen.

[0087] In the first embodiment, the light control layer 16 has a constant specific angle range for diffusing and transmitting incident light in a cross section parallel to the vertical direction and thickness direction of the screen, but the specific angle range may change continuously or stepwise along the vertical direction of the screen. By adopting such a configuration, light can be diffused more effectively in response to the incident angle of image light that changes in the vertical direction of the screen, and a good image can be displayed.

[0088] (7) In the first and third embodiments, the image light deflection unit 10A may have a configuration in which the reflective surfaces 13 are arranged in the vertical direction of the screen with the longitudinal direction being the horizontal direction of the screen (X direction). In such a configuration, the angle θ1 that the reflecting surface 13 makes with a plane parallel to the screen surface may be constant or may be varied in the arrangement direction of the reflecting surface 13.

[0089] (8) In each embodiment, the screens 10 and 30 may be provided with a light absorbing layer that transmits a portion of incident light and absorbs a portion of it to achieve a predetermined transmittance. By providing such a light absorbing layer, it is possible to reduce the black luminance of the image and absorb external light, thereby improving the contrast of the image. Such a light absorbing layer may be newly laminated on the screen 10, 30, for example, or the function of the light absorbing layer may be imparted to the bonding layer 17, 37, the first base material layer 11, the second base material layer 15, etc. Also, the layer forming the reflective surface 13 may have a function of absorbing part of the incident light. In this case, for example, a laminated structure may be used in which the reflective surface side that reflects the image light in the thickness direction of the layer forming the reflective surface 13 is formed of a layer with high reflectivity, and the other surface in the thickness direction is formed of a layer with high light absorption. The light absorbing layer may be a layer colored with a dark colorant such as black or gray.

[0090] (9) In each embodiment, the reflecting surface 13 may be a combination of a curved surface and a flat surface, or may be a folded surface.

[0091] (10) In the first and third embodiments, the image source LS is located at the center of the screen 10, 30 in the horizontal direction and below the screen, but this is not limiting and the image source LS may be located, for example, above the screen 10, 30. In this case, the screen 10, 30 has a configuration in which its up-down direction (Y direction) is reversed. Alternatively, the image source LS may project image light from an oblique direction onto the screens 10 and 30. In this case, the point C is positioned to match the position of the image source LS. By adopting such a configuration, the position of the image source LS can be freely set.

[0092] (11) In each embodiment, the screens 10 and 30 may be configured without at least one of the first base material layer 11 and the second base material layer 15, for example, when the resin layer 12 has sufficient thickness, rigidity, etc. Also, for example, in the first embodiment, when the light-emitting side (+Z side) surface of the screen 10 is bonded to a support plate (not shown), the screen 10 may be configured without the second base material layer 15, and a bonding layer may be provided between the resin layer 12 and the support plate. In the first and second embodiments, the screen 10 may have a configuration in which the light control layer 16 is provided adjacent to and integral with the resin layer 12, and does not include the first base layer 11 and the like. Furthermore, at least one of the first base layer 11 and the second base layer 15 may contain a diffusing material that diffuses light.

[0093] (12) In each embodiment, a hard coat layer for the purpose of preventing scratches may be provided on the surfaces of the light incident side (+Z side) and the light emitting side (-Z side) of the screens 10 and 30. The hard coat layer is formed, for example, by applying an ultraviolet curable resin (e.g., urethane acrylate) having hard coat function to the surfaces of the light incident side and the light emitting side of the screens 10 and 30. Furthermore, in addition to the hard coat layer, one or more layers having appropriate functions such as anti-reflection, ultraviolet absorbing, anti-fouling, anti-static, etc. may be selected and provided on the light-entering and light-emitting surfaces of the screens 10 and 30 depending on the environment and purpose of use of the screens 10 and 30. Furthermore, a touch panel layer or the like may be provided at the position closest to the light-emitting side (viewer side) of the screens 10 and 30.

[0094] In particular, when an anti-reflection layer is provided at the position closest to the light-entering side of the screens 10 and 30, the reflection of image light on the light-entering surface of the screens 10 and 30 is reduced, thereby increasing the amount of light incident on the screens 10 and 30 and improving the brightness of the image. The layer having various functions, such as the hard coat layer, may be provided on either the light-entering side or the light-emitting side of the screens 10 and 30.

[0095] The present invention is not limited to the above-described embodiments, but may be combined with other embodiments as desired. [Explanation of symbols]

[0096] 1. Video display device 10,30 screen 11 First base layer 12 Resin layer 13 Reflective surface 15 Second base layer 16 Light control layer 17,37 Bonding layer 38 Light diffusion layer 10A image light deflection section 10B, 30B Image light diffusion section

Claims

1. an image light deflection unit that changes the direction of at least a portion of the incident image light; an image light diffusion unit that diffuses at least a portion of the incident image light; A screen comprising: a light-entering surface through which image light enters and a light-exiting surface opposed to the light-entering surface through which the image light exits, The image light deflection unit a resin layer having optical transparency; a plurality of reflective surfaces arranged inside the resin layer, the reflective surfaces reflecting at least a portion of incident light; the reflection surfaces are inclined such that, in a cross section parallel to the arrangement direction of the reflection surfaces and the thickness direction of the screen, an end portion of the reflection surfaces on the light incident surface side is positioned lower in the screen up-down direction than an end portion of the reflection surfaces on the light exit surface side, the image light diffusion unit is disposed closer to the light-incident side than the image light deflection unit in the thickness direction of the screen, and diffuses light incident from an oblique direction more than light incident at an incident angle of 0°; A screen featuring.

2. 2. The screen according to claim 1, the image light diffusion section is a light control layer that diffuses and transmits light incident at an incident angle within a specific angle range to a greater extent than light incident at an incident angle outside the specific angle range; A screen featuring.

3. 3. The screen according to claim 2, Light incident at an angle of incidence outside the specified angular range is transmitted without being diffused or is diffused to a lesser extent than light incident at an angle of incidence within the specified angular range. A screen featuring.

4. The screen according to any one of claims 1 to 3, At least a part of the image light is reflected by the reflecting surface to change its direction toward the light output surface; A screen featuring.

5. A screen according to any one of claims 1 to 4, the reflecting surface forms an angle θ1 with a plane parallel to the screen surface in a cross section parallel to the arrangement direction and the thickness direction of the screen, The angle θ1 is equal to or greater than 70° and less than 90°; A screen featuring.

6. 6. The screen according to claim 5, the angle θ1 decreases toward one side along the arrangement direction of the reflecting surfaces; A screen featuring.

7. A screen according to any one of claims 1 to 6, When viewed from the normal direction of the screen surface of the screen, the reflecting surfaces have gaps between them in the arrangement direction. A screen featuring.

8. A screen according to any one of claims 1 to 7, the reflecting surfaces are arranged concentrically around a point located outside the display area of ​​the screen when viewed from the normal direction of the screen surface; A screen featuring.

9. A screen according to any one of claims 1 to 8, the resin layer includes a first resin layer located on a light-incident side and a second resin layer located adjacent to the first resin layer on a light-emitting side, the first resin layer has a plurality of unit optical shapes arranged at an interface with the second resin layer, the unit optical shape has a polygonal shape in a cross section parallel to the arrangement direction and the thickness direction of the screen, the reflecting surface is formed on at least a part of a surface that is angled with respect to a plane parallel to a screen surface in the unit optical shape; A screen featuring.

10. 10. The screen according to claim 9, the unit optical shape has a triangular shape in a cross section parallel to the arrangement direction and the thickness direction of the screen, and has a first surface and a second surface intersecting the first surface; an angle formed by the first surface and a plane parallel to the screen surface is larger than an angle formed by the second surface and a plane parallel to the screen surface; the reflecting surface is formed on at least a part of the first surface; A screen featuring.

11. 10. The screen according to claim 9, Each of the unit optical shapes has a trapezoidal shape in a cross section parallel to the arrangement direction of the unit optical shapes and the thickness direction of the screen, and has a first surface, a second surface facing the first surface in the arrangement direction of the unit optical shapes, and a top surface located between the first surface and the second surface and closest to the light-emitting side, the first surface is angled with respect to a plane parallel to the screen surface; the reflecting surface is formed on at least a part of the first surface; A screen featuring.

12. A screen according to any one of claims 1 to 11, The screen is transparent, the reflective surface is provided by a low refractive index layer having optical transparency and a refractive index lower than that of the resin layer; A screen featuring.

13. A screen according to any one of claims 1 to 11, The screen is transparent, the reflective surface is provided by a semi-transmissive reflective layer that reflects a part of incident light and transmits a part of incident light; A screen featuring.

14. A screen according to any one of claims 1 to 13; an image source that projects image light onto the screen; A video display device comprising:

15. 15. The image display device according to claim 14, the image source is located below the image plane of the screen; A video display device characterized by:

16. an image light deflection unit that changes the direction of at least a portion of the incident image light; an image light diffusion unit that diffuses at least a portion of the incident image light; A screen comprising: a light-entering surface through which image light enters and a light-exiting surface opposed to the light-entering surface through which the image light exits, The image light deflection unit a resin layer having optical transparency; a plurality of reflective surfaces arranged inside the resin layer, the reflective surfaces reflecting at least a portion of incident light; the resin layer includes a first resin layer located on a light-incident side and a second resin layer located adjacent to the first resin layer on a light-emitting side, the first resin layer has a plurality of unit optical shapes arranged at an interface with the second resin layer, Each of the unit optical shapes has a trapezoidal shape in a cross section parallel to the arrangement direction of the unit optical shapes and the thickness direction of the screen, and has a first surface, a second surface facing the first surface in the arrangement direction of the unit optical shapes, and a top surface located between the first surface and the second surface and closest to the light-emitting side, the first surface is angled with respect to a plane parallel to the screen surface; the reflecting surface is formed on at least a part of the first surface, At least a part of the image light is reflected by the reflecting surface to change its direction toward the light output surface; A screen featuring.

Images