Image display sheet and image display

Abstract

This image display sheet (1) comprises: a reflection layer (10) that reflects light incident from one surface (10F1); a diffusion layer (20) that is provided facing the one surface (10F1) of the reflection layer (10) and diffuses transmitted light; an image formation layer (30) that is provided on the reverse side of the diffusion layer (20) from the reflection layer (10) and includes a base image comprising a plurality of light-transmissive pixels (31); and a lens layer (40) that includes a plurality of lenses (41) provided along the image formation layer (30) on the reverse side of the image formation layer (30) from the diffusion layer (20) and forms an image based on the base image by causing light beams transmitted through two or more pixels (31) to cross each other in the air by the plurality of lenses (41).

Description

Image display sheet and image display device

[0001] The present invention relates to an image display sheet and an image display device.

[0002] 2. Description of the Related Art Image display devices that form and display an image in the air are known, and Patent Document 1 listed below discloses such an image display device.

[0003] The image display device disclosed in Patent Document 1 below includes a liquid crystal display having a backlight and displaying a base image made up of a plurality of pixels, and a microlens array in which a plurality of microlenses are arranged two-dimensionally. The plurality of microlenses form an image based on the base image by causing light emitted from two or more pixels to intersect in the air. An image formed in the air in this way is sometimes called an aerial image.

[0004] JP 2013-64996 A

[0005] In such image display devices, there is a demand for eliminating the light source and suppressing unevenness in brightness of the formed aerial image.

[0006] Therefore, an object of the present invention is to provide an image display sheet and an image display device that do not include a light source and that can suppress uneven brightness of an aerial image.

[0007] In order to achieve the above-mentioned object, the image display sheet of the present invention is characterized by comprising a reflective layer that reflects light incident from one side, a diffusion layer that is arranged opposite the one side of the reflective layer and diffuses light that passes through, an image forming layer that is arranged on the opposite side of the reflective layer relative to the diffusion layer and includes a base image consisting of a plurality of light-transmitting pixels, and a lens layer that includes a plurality of lenses arranged along the image forming layer on the opposite side of the diffusion layer relative to the image forming layer, and that uses the plurality of lenses to intersect light that has passed through two or more of the pixels in the air to form an image based on the base image.

[0008] In this image display sheet, external light enters the image forming layer through the lens layer. At least a portion of the light entering the image forming layer passes through the light-transmitting pixels, enters the diffusion layer, and is diffused by the diffusion layer. The diffused light is reflected by the reflective layer, enters the diffusion layer, is diffused by the diffusion layer, and enters the image forming layer. A portion of the light entering the image forming layer passes through the pixels and exits to the outside through the lens layer. As described above, the multiple lenses in the lens layer cause light passing through two or more pixels to intersect in the air to form an image based on the original image. Therefore, this image display sheet can display an aerial image without a light source. Furthermore, this image display sheet has a diffusion layer between the reflective layer and the image forming layer. Therefore, compared to a sheet not including a diffusion layer, unevenness in the brightness of light entering the pixels of the image forming layer from the reflective layer side can be reduced, and unevenness in the brightness of the aerial image can be reduced.

[0009] The reflective layer may be a retroreflective layer that retroreflects light incident from the one surface.

[0010] With this configuration, it is possible to suppress a decrease in the amount of light incident on the pixels of the image forming layer from the reflective layer side, and to suppress a decrease in the brightness of the aerial image.

[0011] The lens layer may be a lenticular lens composed of a plurality of columnar lenses.

[0012] The image display sheet may have a space between the diffusion layer and at least a portion of the image forming layer that includes the base image.

[0013] According to this configuration, light traveling from the image-forming layer toward the diffusion layer is incident on the diffusion layer through the space. Because light propagates while spreading, light traveling from the image-forming layer toward the diffusion layer can be incident on the diffusion layer in a more spread-out state than when the space is not formed, and can be diffused more by the diffusion layer. Furthermore, light traveling from the diffusion layer toward the image-forming layer can be incident on the pixels of the image-forming layer through the space, and can be incident on the pixels in a more spread-out state than when the space is not formed. Therefore, compared to the above case, unevenness in the brightness of light incident on the pixels of the image-forming layer from the reflective layer side can be more effectively suppressed, and unevenness in the brightness of the aerial image can be more effectively suppressed.

[0014] The image display device of the present invention is characterized by comprising the above-mentioned image display sheet and a holding portion that is provided on the opposite side of the diffusion layer relative to the reflective layer and that holds the image display sheet.

[0015] This image display device can realize road signs, advertising billboards, and the like that display aerial images.

[0016] In the above image display device, the holding portion may hold the image display sheet so that one of the main surfaces is non-parallel to a horizontal plane, and the lens layer may be a lenticular lens consisting of a plurality of columnar lenses arranged horizontally.

[0017] With this image display, when the viewpoint shifts horizontally from the front of the image display, the position of the visible aerial image shifts horizontally, so that when passing by the image display, the aerial image appears to move, making the aerial image more noticeable.

[0018] As described above, the present invention provides an image display sheet and an image display device that do not include a light source and that can suppress uneven brightness of an aerial image.

[0019] Fig. 1 is a diagram schematically showing a cross section of an image display sheet in an embodiment of the present invention. Fig. 2 is a diagram showing a lens layer as viewed from the side opposite to the image forming layer side. Fig. 3 is a diagram for explaining the formation of an aerial image. Fig. 4 is a front view schematically showing an image display. Fig. 5 is a diagram schematically showing a cross section of an image display sheet in a modified example.

[0020] Preferred embodiments of the image display sheet and image display device according to the present invention will be described in detail below with reference to the drawings. The embodiments exemplified below are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention can be modified and improved within the scope of the claims without departing from the spirit of the invention. In the drawings referred to below, the dimensions of each component may be changed to facilitate understanding.

[0021] Fig. 1 is a diagram schematically showing a cross section of an image display sheet according to an embodiment of the present invention. As shown in Fig. 1, the image display sheet 1 according to this embodiment mainly comprises a reflective layer 10, a diffusion layer 20, an image forming layer 30, a lens layer 40, an adhesive layer 50, and a release layer 60, and is configured by laminating these multiple layers 40, 30, 20, 10, 50, and 60. The outer shape of the image display sheet 1 according to this embodiment is rectangular, but is not limited to this.

[0022] The reflective layer 10 is a layer that reflects light incident from one surface 10F1. The reflective layer 10 of this embodiment is a prism-type retroreflective layer that retroreflects light incident on the one surface 10F1. The reflective layer 10 includes a plate-shaped holding portion 11 including the one surface 10F1 and a plurality of retroreflective elements 12 provided on the side of the holding portion 11 opposite the one surface 10F1. The holding portion 11 and the retroreflective elements 12 are integral. Therefore, the holding portion 11 and the retroreflective elements 12 are made of the same material, and no connecting portion is formed between the holding portion 11 and the retroreflective elements 12. Examples of the retroreflective elements 12 include triangular pyramidal retroreflective elements and full cube corner retroreflective elements. Examples of materials that constitute the holding portion 11 and the retroreflective elements 12 include transparent resins such as acrylic resins. The configuration of the retroreflective layer is not limited. For example, a specular reflective layer may be provided on the surface of the retroreflective element 12 opposite to the holding part 11. The reflective layer 10 may also be an encapsulated lens type retroreflective layer.

[0023] The diffusion layer 20 is a layer provided opposite one surface 10F1 of the reflective layer 10, and diffuses light that passes through it. The diffusion layer 20 of this embodiment is provided on one surface 10F1 via a light-transmitting adhesive layer (not shown). The diffusion layer 20 may be configured, for example, by dispersing light-transmitting fine particles in a base layer made of a light-transmitting resin. Examples of the resin that constitutes the base layer include methacrylic resin and acrylic resin. Examples of the fine particles include methacrylic resin beads and acrylic resin beads.

[0024] The image forming layer 30 is a layer provided on the opposite side of the reflective layer 10 relative to the diffusion layer 20, and includes a plurality of pixels 31 arranged two-dimensionally along the diffusion layer 20. Of the plurality of pixels 31, at least two pixels 31 are light-transmitting pixels 31, and the remaining pixels 31 are light-opaque pixels 31. A base image is formed by the light-transmitting pixels 31. That is, the image forming layer 30 includes a base image made up of a plurality of light-transmitting pixels. The color of the light-transmitting pixels 31 is not limited, and the image forming layer 30 may include pixels 31 of different colors. All of the pixels 31 may be light-transmitting pixels 31. Adjacent pixels 31 may be adjacent or spaced apart. When adjacent pixels 31 are adjacent, the pixels 31 may be integral. As will be described in detail later, the base image corresponds to an image to be focused in the air, and is an image determined depending on the image and the lens layer 40 described later. For ease of understanding, the number of pixels 31 is reduced in FIG. 1 .

[0025] The image forming layer 30 of this embodiment is formed on the surface of the diffusion layer 20 opposite the reflective layer 10 side by printing using a light-transmitting resin ink and a light-opaque resin ink by gravure printing, screen printing, flexographic printing, inkjet printing, or the like. Also, when all the pixels 31 are light-transmitting pixels 31, they are formed by printing using a light-transmitting resin ink. Note that the image forming layer 30 is not limited to being formed by printing.

[0026] The lens layer 40 is a layer including a plurality of lenses 41 provided along the image forming layer 30 on the side opposite to the diffusion layer 20 side relative to the image forming layer 30. As will be described in detail later, light that has passed through a plurality of light-transmitting pixels 31 that constitute the original image passes through the lens layer 40, and an image based on the original image is formed in the air a predetermined distance away from the lens layer 40.

[0027] FIG. 2 is a view of the lens layer 40 as viewed from the side opposite the image-forming layer 30. As shown in FIGS. 1 and 2 , the lens layer 40 of this embodiment is a lenticular lens in which the lenses 41 are columnar lenses. The columnar lenses 41 extend along the image-forming layer 30 and are arranged in parallel in a direction generally perpendicular to the extension direction. Note that in FIG. 1 , the direction perpendicular to the paper surface is the extension direction of the lenses 41. In this embodiment, adjacent lenses 41 are in contact with each other, and multiple lenses 41 are integrated. However, adjacent lenses 41 may be spaced apart. Each lens 41 covers multiple pixels 31. A surface 41F1 of the lens 41 facing the image-forming layer 30 is a flat surface that is aligned with a surface 30F1 of the image-forming layer 30 facing the lens layer 40, and a surface 41F2 of the lens 41 opposite the image-forming layer 30 is a curved surface that is convexly curved toward the side opposite the image-forming layer 30. The lens layer 40 of this embodiment is provided on the surface 30F1 of the image forming layer 30 via a light-transmitting adhesive layer (not shown). Examples of materials that form the lenses 41 include transparent resins such as acrylic resins.

[0028] The adhesive layer 50 is provided on the side of the reflective layer 10 opposite to the diffusion layer 20 side, and is a layer that is attached to an adherend when the image display sheet 1 is used. Examples of materials that constitute the adhesive layer 50 include acrylic resins and epoxy resins.

[0029] The release layer 60 is a layer provided on the side of the adhesive layer 50 opposite to the reflective layer 10 side. The release layer 60 covers the adhesive layer 50 before use of the image display sheet 1, thereby preventing dust and the like from adhering to the adhesive layer 50. On the other hand, when the image display sheet 1 is used, the release layer 60 is peeled off from the adhesive layer 50. The release layer 60 is made of, for example, a polyester film, a polypropylene film, paper, or the like.

[0030] Next, the formation of an aerial image by the image display sheet 1 will be described.

[0031] 1 , in the image display sheet 1 of this embodiment, external light L is incident on the image forming layer 30 through the lens layer 40. At least a portion of the light L incident on the image forming layer 30 is transmitted through the light-transmitting pixels 31, incident on the diffusion layer 20, and diffused by the diffusion layer 20. The diffused light L is retroreflected by the reflective layer 10, which is a retrosemi-reflective layer, and incident on the diffusion layer 20, and diffused by the diffusion layer 20 before incident on the image forming layer 30. At least a portion of the light L incident on the image forming layer 30 is transmitted through the light-transmitting pixels 31 and emitted to the outside through the lens layer 40.

[0032] 3 is a diagram illustrating the formation of an aerial image. As shown in FIG. 3, a portion of light La1 passing through pixel 31a1 covered by lens 41a of lens layer 40 from the diffusion layer 20 side toward lens layer 40 passes through lens 41a and converges at position P1, a predetermined distance from lens layer 40. A portion of light Lb1 passing through pixel 31b1 covered by lens 41b passes through lens 41b and converges at or near position P1, where it intersects with light La1. A portion of light Lc1 passing through pixel 31c1 covered by lens 41c passes through lens 41c and converges at or near position P1, where it intersects with light La1 and light Lb1. In this way, light La1, Lb1, and Lc1 passing through two or more pixels 31a1, 31b1, and 31c1 converge and intersect at or near position P1, forming a light spot. Furthermore, a portion of light La2 passing through pixel 31a2 covered by lens 41a passes through lens 41a and converges at position P2, which is different from position P1. A portion of light Lc2 passing through pixel 31c2 covered by lens 41c passes through lens 41c and converges at or near position P2, and a portion of light Ld2 passing through pixel 31d2 covered by lens 41d passes through lens 41d and converges at or near position P2. Light La2, Lc2, and Ld2 converging at or near position P2 intersect to form a light spot. In this way, light L passing through multiple pixels 31 forms multiple light spots, and these light spots form an image in the air. This image is based on the original image of the image-forming layer 30. The multiple lenses 41 are adjusted so that light passing through multiple pixels 31 intersect in the air to form an image. Furthermore, the number of pixels 31 for forming one light spot may be two or more, and this number may be different for each light spot.

[0033] The image to be formed is not limited to any particular type and may be, for example, a figure, a symbol, a letter, or a combination thereof, or may be a design such as a road sign. The image to be formed may be a two-dimensional image or a three-dimensional image. When the image to be formed is a three-dimensional image, the distances from the lens layer 40 to two or more light points are different from each other.

[0034] Next, the image display will be described.

[0035] 4 is a front view showing the image display device 100 of this embodiment. As shown in FIG. 4, the image display device 100 is a road sign placed on the shoulder of a road, and mainly comprises an image display sheet 1, a holding unit 110, and a support 120.

[0036] The holding unit 110 is a member provided on the opposite side of the reflective layer 10 from the diffusion layer 20 side and holds the image display sheet 1. In this embodiment, the holding unit 110 is a plate-like member extending in a direction generally parallel to the vertical direction. The image display sheet 1 is held by the holding unit 110 by attaching the adhesive layer 50 of the image display sheet 1 to one main surface 110F1 of the holding unit 110. One surface 10F1 of the reflective layer 10 of the image display sheet 1 is non-parallel to the horizontal plane and generally parallel to the vertical direction. In other words, the holding unit 110 holds the image display sheet 1 in this manner. Furthermore, the columnar lenses 41 of the lens layer 40 of the image display sheet 1 held by the holding unit 110 are aligned horizontally. In other words, the holding unit 110 holds the image display sheet 1 so that the alignment direction of the lenses 41 is horizontal. For ease of understanding, the number of lenses 41 is reduced in FIG. 4 .

[0037] The support 120 in this embodiment is a rod-shaped member extending vertically, with a holding part 110 attached to its upper end and a lower end buried in the road shoulder. The holding part 110 may be, for example, a cylindrical metal pipe with one end open.

[0038] As described above, the image display sheet 1 of this embodiment includes a reflective layer 10, a diffusion layer 20, an image-forming layer 30, and a lens layer 40. The reflective layer 10 reflects light incident from one surface 10F1, and the diffusion layer 20 is disposed opposite the one surface 10F1 of the reflective layer 10 and diffuses light that passes through. The image-forming layer 30 is disposed on the opposite side of the reflective layer 10 relative to the diffusion layer 20 and includes a base image composed of a plurality of light-transmitting pixels 31. The lens layer 40 includes a plurality of lenses 41 disposed along the image-forming layer 30 on the opposite side of the image-forming layer 30 relative to the diffusion layer 20. The lenses 41 cause light that has passed through two or more pixels 31 to intersect in the air, thereby forming an image based on the base image. As described above, in the image display sheet 1 of this embodiment, external light L enters the image-forming layer 30 through the lens layer 40, and an image is formed in the air away from the lens layer 40. Therefore, the image display sheet 1 of this embodiment can display an aerial image without a light source. Furthermore, the image display sheet 1 of this embodiment has the diffusion layer 20 between the reflective layer 10 and the image forming layer 30. Therefore, compared to a case where the diffusion layer 20 is not provided, unevenness in the brightness of the light incident on the pixels 31 of the image forming layer 30 from the reflective layer 10 side can be suppressed, and unevenness in the brightness of the aerial image can be suppressed.

[0039] In the image display sheet 1 of this embodiment, the reflective layer 10 is a retroreflective layer that retroreflects light incident from one surface 10F1, which can suppress a decrease in the amount of light incident on the pixels 31 of the image forming layer 30 from the reflective layer 10 side, and can suppress a decrease in the brightness of the aerial image.

[0040] The image display 100 of this embodiment also includes the image display sheet 1 described above and a holder 110 that is provided on the side opposite the diffusion layer 20 relative to the reflective layer 10 and that holds the image display sheet 1. Therefore, the image display 100 of this embodiment can realize road signs that display aerial images, as described above. Note that the image display 100 is not limited to road signs. For example, the image display 100 can also be an advertising billboard or the like.

[0041] In the image display 100 of this embodiment, the holding unit 110 holds the image display sheet 1 so that one surface 10F1 of the reflective layer 10 is non-parallel to the horizontal plane, and the lens layer 40 is a lenticular lens composed of a plurality of columnar lenses arranged horizontally. According to the image display 100 of this embodiment, when the viewpoint shifts horizontally from the front of the image display 100, the position of the visible aerial image shifts horizontally. Therefore, the image display 100 of this embodiment can make the aerial image appear to move when passing by the image display 100, making the aerial image more noticeable. Note that the one surface 10F1 of the reflective layer 10 of the image display sheet 1 held by the holding unit 110 may be parallel to the horizontal plane. Furthermore, the alignment direction of the lenses 41 may be non-parallel to the horizontal direction, for example, vertical or tilted relative to the vertical direction.

[0042] Although the present invention has been described above using the above embodiment as an example, the present invention is not limited to this.

[0043] For example, in the above embodiment, the reflective layer 10 is described as a retroreflective layer. However, the reflective layer 10 may be configured to reflect light incident on one surface 10F1. For example, the reflective layer 10 may be a flat mirror, and an example of such a configuration is a configuration in which a light-reflecting film is provided on one main surface of a flat substrate made of resin or the like. The light-reflecting film is formed, for example, by metal plating or metal vapor deposition.

[0044] In the above embodiment, the image-forming layer 30 is formed on the surface of the diffusion layer 20 opposite the reflective layer 10 side and in contact with the diffusion layer 20. However, the image-forming layer 30 and the diffusion layer 20 may be spaced apart, and the image display sheet 1 may have a space between the image-forming layer 30 and the diffusion layer 20. Such a modification will be described below. Note that components identical or equivalent to those in the above embodiment are denoted by the same reference numerals and will not be described again unless otherwise specified. FIG. 5 is a diagram schematically illustrating a cross section of an image display sheet in this modification. As shown in FIG. 5, the image display sheet 1 of this modification differs from the image display sheet 1 of the above embodiment mainly in that it further includes a spacer 70.

[0045] The spacer 70 is provided between the image forming layer 30 and the diffusion layer 20, and forms a space 71 between the diffusion layer 20 and a portion of the image forming layer 30 that includes at least the base image. In this modification, the spacer 70 does not overlap with the base image in the thickness direction of the image display sheet 1 and surrounds the base image, but the spacer 70 does not have to surround the base image. The spacer 70 is fixed to the image forming layer 30 and the diffusion layer 20 via an adhesive layer (not shown). The thickness of the spacer 70 is, for example, 10 μm to 50 mm, but is not limited to this. Examples of materials that form the spacer 70 include alkaline resins.

[0046] In this modification, the image forming layer 30 includes a light-transmitting resin film (not shown) arranged along the surface of the lens layer 40 facing the image forming layer 30, and a plurality of pixels 31. The plurality of pixels 31 are provided on one main surface of the resin film by the printing described above. The configuration of the image forming layer 30 is not limited. For example, the plurality of pixels 31 may be provided on the surface of the lens layer 40 facing the image forming layer 30 by the printing described above.

[0047] The image display sheet 1 of this modification has a space 71 between the diffusion layer 20 and at least a portion of the image forming layer 30 including the base image. Therefore, light traveling from the image forming layer 30 toward the diffusion layer 20 enters the diffusion layer 20 through the space 71. Because light propagates while spreading, the light traveling from the image forming layer 30 toward the diffusion layer 20 may enter the diffusion layer 20 in a more spread state than when the space 71 is not formed, and may be more diffused by the diffusion layer 20. Furthermore, the light traveling from the diffusion layer 20 toward the image forming layer 30 enters the pixels 31 of the image forming layer 30 through the space 71, and therefore may enter the pixels 31 in a more spread state than when the space 71 is not formed. Therefore, compared to when the space 71 is not formed, unevenness in the brightness of light entering the pixels 31 of the image forming layer 30 from the reflective layer 10 side can be more effectively suppressed, thereby further suppressing unevenness in the brightness of the aerial image. In this modification, the space 71 is formed by providing a spacer 70 between the image forming layer 30 and the diffusion layer 20. However, there is no limitation on the configuration for forming the space 71. For example, when the image forming layer 30 is housed in a housing, the space 71 may be formed by utilizing the outer periphery of the housing.

[0048] In the above embodiment, the lens layer 40 is a lenticular lens. However, the lens layer 40 may include a plurality of lenses arranged along the image-forming layer 30 on the side opposite the diffusion layer 20 relative to the image-forming layer 30, and may be configured to form an image based on the base image by causing light transmitted through two or more pixels 31 to intersect in the air through the plurality of lenses. The lens layer 40 may be, for example, a lens array consisting of a plurality of lenses arranged two-dimensionally along the image-forming layer 30. In this case, the lenses may be, for example, plano-convex lenses whose surfaces opposite the image-forming layer 30 are convexly curved. The lens layer 40 may also be separated from the image-forming layer 30. In this case, for example, a spacer surrounding the base image is provided between the lens layer 40 and the image-forming layer 30. Examples of materials constituting the spacer include alkaline resins.

[0049] Furthermore, in the above embodiment, the image display sheet 1 provided with the adhesive layer 50 and the release layer 60 has been described as an example, but the adhesive layer 50 and the release layer 60 may be omitted. The image display sheet of the present invention may also include layers other than those exemplified in the above embodiment. For example, in the image display sheet 1 of the above embodiment, a light-transmitting surface protective layer may be provided on the side of the lens layer 40 opposite to the image forming layer 30 side. Examples of materials constituting the surface protective layer include polycarbonate resins and vinyl chloride resins.

[0050] In the above embodiment, the plate-shaped holding portion 110 has been described as an example, but the holding portion 110 may be configured to hold the image display sheet 1, and is not limited to a plate-shaped member.

[0051] As described above, according to the present invention, an image display sheet and an image display device are provided that do not have a light source and can suppress uneven brightness of an aerial image, and can be used in fields such as decorative sheets, road signs, guide signs, and advertising billboards.

Claims

1. A reflective layer that reflects light incident from one side, a diffusion layer provided facing the one side of the reflective layer and diffusing transmitted light, an image forming layer provided on the side opposite to the reflective layer side with respect to the diffusion layer and including a base image composed of a plurality of light-transmissive pixels, and a lens layer including a plurality of lenses provided along the image forming layer on the side opposite to the diffusion layer side with respect to the image forming layer, wherein the plurality of lenses cross light transmitted through two or more of the pixels in the air to form an image based on the base image. The image display sheet is characterized by comprising the above components.

2. The image display sheet according to claim 1, wherein the reflective layer is a retroreflective layer that retroreflects light incident from the one side.

3. The image display sheet according to claim 1, wherein the lens layer is a lenticular lens composed of a plurality of cylindrical lenses.

4. The image display sheet according to claim 1, wherein there is a space between at least a portion including the base image in the image forming layer and the diffusion layer.

5. An image display device comprising the image display sheet according to any one of claims 1 to 4, and a holding portion provided on the side opposite to the diffusion layer side with respect to the reflective layer and holding the image display sheet.

6. The image display device according to claim 5, wherein the holding portion holds the image display sheet such that one main surface is non-parallel to a horizontal plane, and the lens layer is a lenticular lens composed of a plurality of cylindrical lenses arranged in a horizontal direction.

Images