Patent Publication Number: US-2019196211-A1

Title: Lenticular display and method of manufacturing lenticular display

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of International Application No. PCT/JP2017/027719, filed Jul. 31, 2017, the disclosure of which is incorporated herein by reference in its entirety. Further, this application claims priority from Japanese Patent Application No. 2016-190293, filed Sep. 28, 2016, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a lenticular display and a method of manufacturing a lenticular display. 
     2. Related Art 
     A lenticular display, which has a lenticular lens composed of a plurality of convex lenses each of which has a convex front surface and that are arranged in parallel, is known as a medium for displaying different images depending on the viewing angle. 
     In general, in the lenticular display, image strip groups (lenticular image), each of which is a combination of a plurality of interlaced images, are arranged on a back surface (a surface opposite to a front surface of each of the convex lenses) side of the lenticular lens. When the image strip groups are observed through the lenticular lens, one type of image or two or more types of images included in the image strip groups is/are displayed depending on the observation angle. 
     JP1999-095168A (JP-H11-095168A) discloses an example of such a lenticular display, which includes a lenticular sheet (lenticular lens) and a sampling image (lenticular image) that is composed of a left-eye image, a right-eye image, and a blank pixel. 
     JP5500478B discloses a lenticular lens that includes a plurality of cylindrical lenses (convex lenses), and display images (lenticular image) displayed in a region excluding a region near the boundary between adjacent cylindrical lenses. 
     SUMMARY 
     Here, for example, referring to  FIGS. 6 to 8 , a case where a display image A (hereinafter referred to as “image A”) and a display image B (hereinafter referred to as “image B”), which include characters that differ from each other, are displayed by using one lenticular display will be described. 
     As shown in  FIG. 8 , a lenticular display  100  has a lenticular lens  104  that is composed of a plurality of convex lenses  102  each of which has a convex front surface. On the back surface side (lower side in  FIG. 8 ) of the lenticular lens  104 , display image strips An and Bn (hereinafter referred to as “image strips An and Bn”) for displaying the display images A and B are arranged in parallel at corresponding positions so that the display images A and B can be switched depending on the viewing angle. The image strips An and Bn constitute a lenticular image  106 . 
     To be specific, when the lenticular display  100  includes the lenticular lens  104  in which, for example, N pieces of convex lenses  102  (where N is an integer larger than or equal to 2) are arranged in parallel, for example, as shown in  FIG. 6 , in a region S under a convex lens  102  that is in the n-th position from one end in the parallel-arrangement direction of the convex lenses  102  (where n is an integer larger than or equal to 1), as shown in  FIG. 7 , an image strip An and an image strip Bn, which are respectively extracted by dividing each of the images A and B into stripe shapes, are arranged in parallel in an interlaced manner so as to be adjacent to each other. 
     As shown in  FIG. 8 , under each of the 1st to N-th convex lenses  102 , as with the n-th convex lens  102 , image strips An and Bn, which are respectively extracted from the images A and B, are arranged in parallel at corresponding positions. Depending on the viewing angle of an observer through the lenticular lens  104 , the image A is displayed when the image strips An extracted from the image A are combined, or an image B is displayed when the image strips Bn extracted from the image B are combined. 
     Here, as shown in  FIG. 8 , light that has entered the lenticular lens  104  is reflected by a front surface of the lenticular image  106 , and a part of the light passes through the lenticular image  106 . The light that has passed through the lenticular image  106  is reflected by a front surface of an object disposed on the back surface side (lower side in  FIG. 8 ) of the lenticular image  106  (such as a sheet of paper  108  that is affixed to the back surface of the lenticular image  106 ), and stray light is generated in the lenticular lens  104 . 
     When the stray light is emitted from the lenticular lens  104  together with light reflected by the front surface of the lenticular image  106 , overlapping of images A and B may occur and discrimination between the images A and B may decrease. In particular, overlapping of the images A and B is likely to occur at a position where an image observed by an observer (image that is actually seen) is switched from the image A to the image B or from the image B to the image A, that is, for example, at an angle at which the left and right eyes observe different images (the left eye sees the image A and the right eye sees the image B) as shown in  FIG. 8 . 
     The lenticular display disclosed in JP1999-095168A (JP-H11-095168A) suppresses overlapping of images by providing a blank pixel between a left-eye image and a right-eye image of the sampling image (lenticular image). However, it is difficult to suppress generation of stray light in the lenticular sheet (lenticular lens) due to light reflected on the back surface side of the sampling image (lenticular image). 
     Likewise, with the lenticular lens disclosed in JP5500478B, decrease in image quality due to mixing of display images is suppressed by displaying the display images (lenticular image) in a region excluding a region near the boundary between adjacent cylindrical lenses. However, it is difficult to suppress generation of stray light in the lenticular lens due to light reflected on the back surface side of the display image (lenticular image). 
     In consideration of the above facts, it is an object of the present disclosure to provide a lenticular display and a method of manufacturing a lenticular display each of which can suppress decrease of ability in discriminating between display images due to stray light. 
     According to a first aspect of the present disclosure, a lenticular display has: a lenticular lens in which a plurality of convex lenses are arranged in parallel, each of the convex lenses having a convex front surface; a lenticular image provided on a back surface side of each of the convex lenses, the back surface being a surface of the convex lens opposite to the front surface; and an anti-reflection layer provided on a back surface side of the lenticular image, the back surface being a surface of the lenticular image opposite to a front surface of the lenticular image facing the lenticular lens. The lenticular image includes a plurality of display image strips that are extracted each in a stripe shape from a plurality of display images and that are arranged at corresponding positions on the back surface side of each of the convex lenses, and a transparent-slit image strip that is provided between each pair of the plurality of display image strips that are adjacent to each other and that are extracted from the display images that differ from each other. 
     With the structure described above, decrease of ability in discriminating between the display images can be suppressed because of the following: generation of stray light is suppressed by reducing reflection of light that has entered the convex lens by using the anti-reflection layer, which is provided on the back surface side of the lenticular image; and overlapping of the display images is suppressed by using the transparent-slit image strip, which is provided between each pair of the display image strips that are adjacent to each other. 
     In the present disclosure, the term “display image” refers to an image to be displayed by the lenticular display, that is, an image to be recognized by an observer when the observer observes the lenticular display from the lenticular lens side. In the present disclosure, the term “transparent” means a property of having a total light transmittance of 80% or higher for light in the wavelength range of 400 to 700 nm. 
     In the present disclosure, “a lenticular image provided on a back surface side of each of the convex lenses, the back surface being a surface of the convex lens opposite to the front surface” includes, in addition to a structure in which the lenticular image is disposed in contact with the back surface of the convex lens or separated from the back surface, a structure in which the lenticular image is directly formed on the convex lens (lenticular lens). 
     Likewise, in the present disclosure, “an anti-reflection layer provided on a back surface side of the lenticular image, the back surface being a surface of the lenticular image opposite to a front surface of the lenticular image facing the lenticular lens” includes, in addition to a structure in which the anti-reflection layer is disposed in contact with the back surface of the lenticular image or separated from the back surface, a structure in which the anti-reflection layer is directly formed on the back surface of the lenticular image. 
     According to a second aspect of the present disclosure, in the lenticular display according to the first aspect, a residual density of the display images is 0% or higher and 40% or lower. 
     With the structure described above, because the residual density of the display images is 0% or higher and 40% or lower, compared with a case where the residual density is higher than 40%, the viewability of the display image can be further improved. 
     Here, in the present disclosure, the term “residual density” refers to a value that is obtained by: capturing an observation image from a plurality of angles on the front surface side of the lenticular lens by using a digital camera; binarizing the captured observation image; quantizing, into 256-level digital data, the density of each of a display image strip An (for example, an image strip having a black color of uniform density) that is supposed to be seen at any one of the plurality of angles and a display image strip Bn (for example, an image strip having a white color of uniform density) that is not supposed to be seen at the angle; and performing calculation by using the following equation (1). In the present disclosure, the term “observation image” refers to an image that is actually seen by an observer when the observer sees the display images (display image strips) through the lenticular lens. 
       Residual Density (%)=(the density of the display image strip  Bn )/(the density of the display image strip  An )  (1)
 
     According to a third aspect of the present disclosure, in the lenticular display according to the first aspect or the second aspect, a width of the transparent-slit image strip in an arrangement direction is 5% or larger and 50% or smaller of a width of each of the convex lenses in a parallel-arrangement direction. 
     With the structure described above, because the width of the transparent-slit image strip is 5% or larger of the width of the convex lens, compared with a structure in which the width of the transparent-slit image strip is smaller than 5% of the width of the convex lens, overlapping of the display images can be suppressed. Moreover, because the width of the transparent-slit image strip is 50% or smaller of the width of the convex lens, compared with a structure in which the width of the transparent-slit image strip is larger than 50% of the width of the convex lens, the continuity of the plurality of display images can be maintained. 
     According to a fourth aspect of the present disclosure, in the lenticular display according to any one of the first to third aspects, the plurality of display images each include a character. 
     When display images each include a character, readability of the display images is particularly necessary. With the structure described above, because the lenticular display is provided with the anti-reflection layer and the transparent-slit image strip, decrease of ability in discriminating between the display images can be suppressed, and the characters can be easily recognized. 
     According to a fifth aspect of the present disclosure, in the lenticular display according to any one of the first to fourth aspects, the lenticular image is formed on a recording medium that is bonded to a back surface of the lenticular lens. 
     With the structure described above, because the lenticular image is formed on the recording medium that is bonded to the back surface of the lenticular lens, compared with a structure in which the lenticular image is directly formed on the lenticular lens, the lenticular image can be easily formed. 
     According to a sixth aspect of the present disclosure, in the lenticular display according to any one of the first to fourth aspects, the lenticular image is formed on a back surface of the lenticular lens. 
     With the structure described above, because the lenticular image is directly formed on the back surface of the lenticular lens, compared with a structure in which a recording medium on which the lenticular image has been formed is bonded to the lenticular lens, the lenticular image can be formed at low costs. 
     According to a seventh aspect of the present disclosure, a method of manufacturing a lenticular display includes a step of forming a lenticular image by arranging a plurality of display image strips, which are extracted each in a stripe shape from a plurality of display images, at corresponding positions and by providing a transparent-slit image strip between each pair of the plurality of display image strips that are adjacent to each other and that are extracted from the display images that differ from each other; a step of providing the lenticular image on a back surface side of a lenticular lens in which a plurality of convex lenses are arranged in parallel, each of the convex lenses having a convex front surface, the back surface being a surface of the lenticular lens opposite to the front surface; and a step of providing an anti-reflection layer on a back surface side of the lenticular image, the back surface being a surface of the lenticular image opposite to a front surface of the lenticular image facing the lenticular lens. 
     With the method described above, decrease of ability in discriminating between display images can be suppressed because of the following: generation of stray light is suppressed by reducing reflection of light that has entered the convex lens by providing the anti-reflection layer on the back surface side of the lenticular image; and overlapping of the display images is suppressed by providing the transparent-slit image strip between each pair of the display image strips that are adjacent to each other. 
     According to an eighth aspect of the present disclosure, in the method of manufacturing a lenticular display according to the seventh aspect, a width of the transparent-slit image strip in an arrangement direction is 5% or larger and 50% or smaller of a width of each of the convex lenses in a parallel-arrangement direction. 
     With the method described above, because the width of the transparent-slit image strip is 5% or larger of the width of the convex lens, compared with a structure in which the width of the transparent-slit image strip is smaller than 5% of the width of the convex lens, overlapping of the display images can be suppressed. Moreover, because the width of the transparent-slit image strip is 50% or smaller of the width of the convex lens, compared with a structure in which the width of the transparent-slit image strip is larger than 50% of the width of the convex lens, the continuity of the plurality of display images can be maintained. 
     According to a ninth aspect of the present disclosure, in the method of manufacturing a lenticular display according to the seventh aspect or the eighth aspect, the plurality of display images each include a character. 
     When display images each include a character, readability of the display images is particularly necessary. With the structure described above, because the lenticular display is provided with the anti-reflection layer and the transparent-slit image strip, decrease of ability in discriminating between the display images can be suppressed, and the characters can be easily recognized. 
     According to a tenth aspect of the present disclosure, in the method of manufacturing a lenticular display according to any one of the seventh to ninth aspects, the lenticular image is formed on a front surface of a recording medium, and the front surface of the recording medium and the back surface of the lenticular lens are affixed to each other. 
     With the method described above, the lenticular display can be manufactured by affixing the recording medium, on which the lenticular image has been formed, and the lenticular lens to each other. Therefore, compared with a method in which the lenticular image is formed on the lenticular lens, the lenticular image can be easily formed. 
     According to an eleventh aspect of the present disclosure, in the method of manufacturing a lenticular display according to any one of the seventh to ninth aspects, the lenticular image is formed on the back surface of the lenticular lens. 
     With the method described above, the lenticular display can be manufactured by directly forming the lenticular image on the back surface of the lenticular lens. Therefore, compared with a method in which a recording medium on which the lenticular image has been formed is bonded to a lenticular lens, the lenticular image can be formed at low costs. 
     With the present disclosure, decrease of ability in discriminating between display images due to stray light can be suppressed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments according to the technique of the present disclosure will be described in detail based on the following figures, wherein: 
         FIG. 1  is a perspective view illustrating the structure of a lenticular display according to a first embodiment; 
         FIG. 2  shows a side view and a plan view illustrating the structure of the lenticular display according to the first embodiment; 
         FIG. 3  is an exploded view of the lenticular display shown in  FIG. 2 ; 
         FIG. 4  is a side view illustrating the structure in the thickness direction of a lenticular display according to a second embodiment; 
         FIG. 5  is a side view illustrating the structure in the thickness direction of a lenticular display according to a third embodiment; 
         FIG. 6  illustrates two display images that are individually displayed by an existing lenticular display; 
         FIG. 7  illustrates image strip groups in a region S in  FIG. 6 ; and 
         FIG. 8  is a side view illustrating the structure in the thickness direction of an existing lenticular display including the image strip groups shown in  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     First Embodiment 
     Hereinafter, referring to  FIGS. 1 to 3 , a lenticular display according to a first embodiment of the present disclosure will be described. In the figures, the X-direction is the width direction of the lenticular display, the Y-direction is the length direction (longitudinal direction) of the lenticular display, and the Z-direction is the thickness direction of the lenticular display. 
     Structure of Lenticular Lens 
     As shown in  FIG. 1 , a lenticular display  10  according to the present embodiment includes, for example, a lenticular lens  14  composed of a plurality of convex lenses  12 . Each of the convex lenses  12  is a cylindrical lens having a substantially semi-cylindrical shape. The convex lens  12  has a front surface  12 A (upper surface in  FIG. 1 ) which has a spherically convex surface and a back surface  12 B (lower surface in  FIG. 1 ) which is opposite to the front surface  12 A. The convex lenses  12  are arranged in parallel in the width direction (X-direction). 
     The lenticular lens  14 , that is, each of the convex lenses  12 , is made of a light-transmissive resin material. Examples of the resin material used include a polymethyl methacrylate resin (PMMA), a polycarbonate resin, a polystyrene resin, a methacrylate-styrene copolymer resin (MS resin), an acrylonitrile-styrene copolymer resin (AS resin), a polypropylene resin, a polyethylene resin, a polyethylene terephthalate resin, a glycol-modified polyethylene terephthalate resin, a polyvinyl chloride resin (PVC), a thermoplastic elastomer, a copolymer of any of the these, and a cycloolefin polymer. 
     In consideration of ease of melt extrusion, preferably, for example, any of the following resins, each of which has a low melt viscosity, is used: a polymethyl methacrylate resin (PMMA), a polycarbonate resin, a polystyrene resin, a methacrylate-styrene copolymer resin (MS resin), a polyethylene resin, a polyethylene terephthalate resin, and a glycol-modified polyethylene terephthalate resin. 
     More preferably, a glycol-modified polyethylene terephthalate resin is used, because a lens shape formed on the surface of an embossing roller can be easily transferred and a crack is not likely to be formed in a lens layer during embossing. The lenticular lens  14  may include a plurality of resin materials. 
     In view of printability, workability, and image resolution, the width (lens pitch) of the convex lens  12  is preferably larger than or equal to 50 LPI (lines per inch, the number of lenses per inch (2.54 cm)) and smaller than or equal to 300 LPI, and, more preferably, larger than or equal to 100 LPI and smaller than or equal to 200 LPI. A lenticular image  16  is provided on a back surface  12 B side of the convex lens  12 , that is, on the back surface  14 B side of the lenticular lens  14 . 
     To be specific, the lenticular image  16  is formed (printed) on a front surface  18 A of a film  18 , which is a recording medium made of a transparent resin. The front surface  18 A of the film  18  is affixed to the back surface  14 B of the lenticular lens  14  via a transparent bonding layer (not shown). 
     Structure of Lenticular Image 
     For example, the lenticular image  16  is composed of image strip groups that include the display image strips  20  and  22  for individually displaying two display images. To be specific, as shown in  FIG. 2 , the display image strips  20  and  22 , which are extracted each in a stripe shape from the display images, are arranged at corresponding positions pairwise for each convex lens  12 . 
     The display image strips  20  and  22  extend in the longitudinal direction (Y-direction) of the lenticular lens  14 . The display image strips  20  and  22  are alternately arranged with spaces therebetween in the width direction (X-direction) of the lenticular lens  14 . A transparent-slit image strip  24  of the lenticular image  16  is disposed between each pair of the display image strips  20  and  22  that are adjacent to each other. 
     The widths of the plurality of display image strips  20  and  22  in the arrangement direction (X-direction) are substantially the same, and the widths of the plurality of transparent-slit image strips  24  in the arrangement direction (X-direction) are also substantially the same. If the width of each of the transparent-slit image strips  24  in the arrangement direction (X-direction) is too small, it is difficult to suppress overlapping of the display image strips  20  and  22  (display images). If the width is too large, it is difficult to maintain the continuity of the display image strips  20  and  22  (display images). 
     Therefore, the width of each of the transparent-slit image strips  24  in the arrangement direction (X-direction) is preferably 5% or larger and 50% or smaller, more preferably 10% or larger and 30% or smaller, and most preferably 12% or larger and 20% or smaller of the width of the convex lens  12  in the parallel-arrangement direction (X-direction). The widths of the transparent-slit image strips  24  in the arrangement direction (X-direction) may be different from each other. 
     In the present embodiment, the display image strips  20  and  22  (display images) each include a character. An anti-reflection layer  26  is provided on the back surface side of the lenticular image  16 , that is, on a back surface  18 B side of the film  18 , the back surface  18 B being opposite to the front surface  18 A. 
     Structure of Anti-Reflection Layer 
     The anti-reflection layer  26  is a layer having a low reflectance over the entire visible spectrum of 400 nm to 700 nm (wide-band low reflectance). The material of the anti-reflection layer is not particularly limited. An organic or an inorganic material can be used, and a commercially available anti-reflection film may be used. 
     Examples of an organic anti-reflection film include DUV 30 series and DUV-40 series made by Brewer Science, Inc.; AR-2, AR-3, and AR-5 made by Shipley Company; and ARC series made by Nissan Chemical Corporation. Examples of the material of an inorganic anti-reflection film include titanium dioxide, titanium nitride, chromium oxide, niobium oxide, tantalum oxide, carbon, silicon dioxide, and amorphous silicon. 
     The anti-reflection layer may be a single layer or a multilayer. When the anti-reflection layer has a multilayer structure, a plurality of layers that include different materials may be used in combination. For example, as shown in  FIG. 2 , the anti-reflection layer may be a multilayer film in which a plurality of layers (in the present embodiment, four layers), which are high-refractive-index films  26 A including an inorganic material and low-refractive-index films  26 B including an inorganic material, are alternately stacked. 
     The term “high-refractive-index film” refers to a film that has a refractive index of 1.7 or higher for light having a wavelength of 500 nm, and that includes, for example, titanium oxide or niobium oxide, as an inorganic material. The term “low-refractive-index film” refers to a film that has a refractive index lower than 1.7 for light having a wavelength of 500 nm, and that includes, for example, silicon dioxide (silica) as an inorganic material. 
     The anti-reflection layer  26  is vapor-deposited over the entirety of the back surface  18 B of the film  18  by using a vacuum deposition method. The material and the thickness of the anti-reflection layer  26  are not particularly limited, and may be set in accordance with a required level of reflectance. For example, in the present disclosure, a stack of titanium-oxide-including layers/silicon-dioxide-including layers is used as the an inorganic multilayer film  1 , and a stack of niobium-pentoxide-including layers/silicon-dioxide-including layers is used as an inorganic multilayer film  2 . 
     In particular, preferably, the material and the thickness of the anti-reflection layer  26 , and the width of the transparent-slit image strip  24  are set so that the residual density of the display image strips  20  and  22  (display images) is 0% or higher and 40% or lower when the lenticular image  16  is observed from a front surface  12 A side of the convex lens  12 , that is, the front surface  14 A side of the lenticular lens  14 . More preferably, the residual density is 30% or lower, and most preferably 28% or lower. 
     Method of Manufacturing Lenticular Display 
     When manufacturing the lenticular display  10 , first, for example, the display image strips  20  and  22  (the display image strips An and Bn in  FIG. 7 ) are extracted by respectively dividing the display image A and the display image B shown in  FIG. 6  into stripe shapes. 
     Then, as shown in  FIG. 3 , the display image strips  20  and  22  are formed on the transparent film  18  by printing the display image strips  20  and  22  at corresponding positions on the front surface  18 A of the film  18  by using an inkjet method. The method of printing the display image strips  20  and  22  is not limited to an inkjet method, and an offset printing method, an electrophotographic method, or the like may be used. An offset printing method and an inkjet method are preferably used, in view of characteristics such as printing precision and suitability for wide-variety small-lot production. 
     When forming the display image strips  20  and  22  on the film  18 , the transparent-slit image strips  24  are formed between the display image strips  20  and the display image strips  22  by disposing the display image strips  20  and  22  with distances therebetween. 
     That is, in the lenticular display  10  according to the present embodiment, the transparent-slit image strips  24  are formed by providing the film  18  with regions in which no display image strips are disposed. Through the above process, the lenticular image  16 , which includes the display image strips  20  and  22  and the transparent-slit image strips  24 , is formed. 
     Next, the lenticular image  16  is provided on the back surface  14 B side of the lenticular lens  14  by affixing the front surface  18 A of the film  18  to the back surface  14 B of the lenticular lens  14  via a transparent bonding layer (not shown). The anti-reflection layer  26  is provided on the back surface side of the lenticular image  16  by vapor-depositing the anti-reflection layer  26  on the back surface  18 B of the film  18 . Through the above process, the lenticular display  10  is manufactured. 
     Functions and Effects 
     As shown in  FIG. 2 , an observer observes the lenticular image  16  from the front surface  14 A side of the lenticular lens  14  through the lenticular lens  14 . At this time, with the present embodiment, because the anti-reflection layer  26  is provided on the back surface side of the lenticular image  16 , reflection of light that has entered the convex lens  12  is suppressed by the anti-reflection layer  26 , and thereby generation of stray light in the lenticular lens  14  is suppressed. 
     In the present embodiment, the transparent-slit image strip  24  is provided between each pair of the display image strips  20  and  22  that are adjacent to each other. Therefore, even if different images are observed with the left and right eyes (for example, an image of the display image strip  20  with the left eye and an image of the transparent-slit image strip  24  with the right eye) at a position where an image observed by an observer switches, overlapping of the images is suppressed, because the image of the transparent-slit image strip  24  is transparent. 
     That is, by providing the transparent-slit image strip  24 , overlapping of a half of the image of the display image strip  20  and a half the image of the display image strip  22  occurs only negligibly or does not occur. Therefore, overlapping of the display image strips  20  and  22  (display images) can be suppressed, and decrease of ability in discriminating between the display image strips  20  and  22  (display images) can be suppressed. 
     In the present embodiment, readability is particularly necessary, because the display image strips  20  and  22  (display images) each include a character. Because decrease of ability in discriminating between the display image strips  20  and  22  is suppressed, the characters can be easily recognized. 
     Moreover, with the present embodiment, by setting the width of the transparent-slit image strip  24  in the arrangement direction to be 5% or larger of the width of the convex lens  12  in the parallel-arrangement direction, overlapping of the image of the display image strip  20  and the image of the display image strip  22  can be further suppressed by the transparent-slit image strip  24 . Furthermore, by setting the width of the transparent-slit image strip  24  in the arrangement direction to be 50% or smaller of the width of the convex lens in the parallel-arrangement direction, continuity of the display image strips  20  and  22  can be further maintained. 
     With the present embodiment, the lenticular image  16  is formed on the film  18 , which is bonded to the back surface  14 B of the lenticular lens  14 . Therefore, compared with a structure in which the lenticular image  16  is directly formed on the lenticular lens  14 , the lenticular image  16  can be easily formed. 
     With the present embodiment, the anti-reflection layer  26  is formed by using a vacuum deposition method. Therefore, compared with a structure in which the anti-reflection layer  26  is formed on the back surface  18 B of the film  18  by application or bonding, the anti-reflection layer  26  does not easily peel off, and the anti-reflection layer  26  can be formed with high precision. 
     With the present embodiment, by setting the material and the thickness of the anti-reflection layer  26  and the width of the transparent-slit image strip  24  so that the residual density of the display image strips  20  and  22  is 0% or higher and 40% or lower, the viewability of the display image strips  20  and  22  can be further improved. 
     Second Embodiment 
     Hereinafter, referring to  FIG. 4 , a lenticular display according to a second embodiment of the present disclosure will be described. Description of elements of the second embodiment that are the same as those of the first embodiment will be omitted as far as possible. 
     Structure 
     As shown in  FIG. 4 , as with the lenticular display  10  according to the first embodiment, a lenticular display  30  according to the present embodiment includes a lenticular lens  34  composed of a plurality of convex lenses  32 . Each of the convex lenses  32  (the lenticular lens  34 ) is made of a transparent resin material. 
     A lenticular image  36  is provided on a back surface  32 B side of the convex lens  32 , that is, on a back surface  34 B side of the lenticular lens  34 . To be specific, image strip groups including display image strips  40  and  42  of the lenticular image  36  are directly formed (printed) on the back surface  34 B of the lenticular lens  34 . 
     The display image strips  40  and  42  are alternately arranged with spaces therebetween in the width direction (X-direction) of the lenticular lens  34 . A transparent-slit image strip  44  of the lenticular image  36  is disposed between each pair of the display image strips  40  and  42  that are adjacent to each other. An anti-reflection layer  46  is provided on the back surface side of the lenticular image  36 , that is, on the back surface  34 B side of the lenticular lens  34 . 
     For example, the anti-reflection layer  46  is made from a single-layer film that includes a large number of silicon dioxide particles each having a hollow portion, that is, hollow silica particles  46 A. The anti-reflection layer  46  is formed by applying a coating agent including the hollow silica particles  46 A to the entirety of the back surface  34 B of the lenticular lens  34 . 
     Functions and Effects 
     With the present embodiment, the lenticular image  36  is directly formed (printed) on the back surface  34 B of the lenticular lens  34 . Therefore, compared with a structure in which a recording medium on which the lenticular image  36  has been formed is bonded to the lenticular lens  34 , the number of components and the number of working steps can be reduced, and the lenticular image  36  can be formed at low costs. 
     With the present embodiment, the anti-reflection layer  46  is formed on the back surface  34 B of the lenticular lens  34  by applying a coating agent including the hollow silica particles  46 A. Therefore, compared with a structure in which the anti-reflection layer  46  is formed by using a vacuum deposition method or the like, the anti-reflection layer  46  can be easily formed. 
     Third Embodiment 
     Hereinafter, referring to  FIG. 5 , a lenticular display according to a third embodiment of the present disclosure will be described. Descriptions of elements of the third embodiment that are the same as those of the first embodiment and the second embodiment will be omitted. 
     Structure 
     As shown in  FIG. 5 , a lenticular display  50  according to the present embodiment includes a lenticular lens  54  composed of a plurality of convex lenses  52 , as with the lenticular displays  10  and  30  according to the first embodiment and the second embodiment. 
     A lenticular image  56  is provided on a back surface  52 B side of the convex lens  52 , that is, on a back surface  54 B side of the lenticular lens  54 . To be specific, image strip groups including display image strips  60  and  62  of the lenticular image  56  are formed (printed) on a front surface  58 A of a film  58 , which is a recording medium made of a transparent resin. The front surface  58 A of the film  58  is affixed to the back surface  54 B of the lenticular lens  54  via a bonding layer (not shown). 
     The display image strips  60  and  62  are alternately arranged with spaces therebetween in the width direction (X-direction) of the lenticular lens  54 . A transparent-slit image strip  64  of the lenticular image  56  is disposed between each pair of the display image strips  60  and  62  that are adjacent to each other. An anti-reflection layer  66  is provided on the back surface side of the lenticular image  56 , that is, on a back surface  58 B side of the film  58 . 
     The anti-reflection layer  66  is formed on the back surface  58 B of the film  58  and is composed of a fine recess-protrusion structure in which the distance between protrusions  66 A that are adjacent to each other is smaller than or equal to the wavelength of visible light (for example, about 0.1 μm). For example, the recess-protrusion structure is formed by, after forming the lenticular image  56  on the front surface  58 A of the film  58 , pressing a mold, whose surface has a recess-protrusion shape, against the back surface  58 B of the film  58  and thereby transferring the recess-protrusion shape to the film  58 . 
     Functions and Effects 
     With the present embodiment, the anti-reflection layer  66  is provided on the film  58  by forming a fine recess-protrusion structure on the back surface  58 B of the film  58 . Therefore, compared with a structure in which the anti-reflection layer  66  is formed by using a vacuum deposition method or the like, the anti-reflection layer  66  can be easily formed at low costs. 
     Other Embodiments 
     The present disclosure is not limited to the embodiments described above as examples, and various embodiments are possible within the scope of the present disclosure. The embodiments may be combined as appropriate. 
     For example, in the embodiments described above, one of each of the display image strips  20 ,  22 ,  40 ,  42 ,  60 , and  62  is arranged below a corresponding one of the convex lenses  12 ,  32 , and  52 . However, a plurality of each of the display image strips  20 ,  22 ,  40 ,  42 ,  60 , and  62  may be arranged below a corresponding one of the convex lens  12 ,  32 , and  52 . By increasing the number of display image strips that are arranged below each of the convex lenses  12 ,  32 , and  52 , resolution can be increased. 
     In the embodiments described above, the lenticular displays  10 ,  30 , and  50  are each structured to display two types of display images. However, the lenticular displays  10 ,  30 , and  50  each may be structured to display three or more types of display images. 
     In the first and third embodiments, the resin films  18  and  58  are each used as a recording medium. However, it is sufficient that a recording medium is transparent. For example, the recording medium may be made of glass. In the third embodiment, the anti-reflection layer  66  is formed on the back surface  58 B of the film  58 . However, the anti-reflection layer  66  may be formed on the back surface  58 B side of the film  58  by bonding another film, on which a fine recess-protrusion structure has been formed, to the back surface  58 B of the film  58 . 
     For example, the anti-reflection layers  26  and  66  may be disposed so as to be separated from the back surfaces  18 B and  58 B of the films  18  and  58  by disposing the anti-reflection layers  26  and  66  via other resin layers between the anti-reflection layers  26  and  66  and the back surfaces  18 B and  58 B of the films  18  and  58 . The structures of the anti-reflection layers  26 ,  46 , and  66  are not limited to those in the embodiments described above, and other known anti-reflection layers may be used. 
     For example, in the first embodiment, the transparent-slit image strip  24  is formed by providing a region in which no image strip is disposed between each pair of the display image strips  20  and  22  printed on the film  18 . However, a method of forming the transparent-slit image strip  24  is not limited to that in the embodiment. For example, the transparent-slit image strip  24  may be formed by using a method that includes: arranging a film on which the display image strips  20  have been printed and a film on which the display image strips  22  have been printed with gaps therebetween; and filling the gaps between the films with a transparent resin material. 
     The transparent-slit image strips need not be provided between all pairs of the display image strips  20  and  22 ,  40  and  42 , and  60  and  62 . For example, the transparent-slit image strips need not be formed in regions where the colors of the display image strips  20  and  22 ,  40  and  42 , and  60  and  62  are respectively the same, that is, in regions where the color does not change when the display image strips  20  and  22 ,  40  and  42 , and  60  and  62  are respectively switched. 
     In the first embodiment, the convex lens  12  has a spherical front surface  12 A. However, it is sufficient that the convex lens  12  has a convex front surface  12 A, and, for example, the front surface  12 A may be non-spherical. For example, the convex lens  12  may have a triangular cross-sectional shape. 
     EXAMPLES 
     Hereinafter, Examples 1 to 12 of the present disclosure and comparative examples 1 to 4 will be specifically described. However, the present disclosure is not limited to the Examples described below. Here, the image viewability (visibility) of the Examples and comparative examples were visually evaluated and graded in five levels from A to E, and grades A to C were determined as in an allowable range as a product. Table 1 shows the evaluation results. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Lenticular Lens 
                 Lenticular Image 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Lens 
                 Transparent Image 
                   
                 Anti-Reflection Layer 
                 Evaluation 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Pitch 
                 Portion/Lens 
                 Image 
                   
                 Presence/ 
                   
                 Residual 
                 Image 
               
               
                 Examples 
                 Material 
                 LPI 
                 Width (%) 
                 Groups 
                 Character 
                 Absence 
                 Structure 
                 Density (%) 
                 Viewability 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 Example 1 
                 Glycol Modified 
                 100 
                 18% 
                 2 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 25 
                 A 
               
               
                   
                 PET 
                   
                   
                   
                   
                   
                 Film 1 
               
               
                 Example 2 
                 Glycol Modified 
                 100 
                 25% 
                 2 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 40 
                 B 
               
               
                   
                 PET 
                   
                   
                   
                   
                   
                 Film 1 
               
               
                 Example 3 
                 Glycol Modified 
                 100 
                 12% 
                 3 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 28 
                 A 
               
               
                   
                 PET 
                   
                   
                   
                   
                   
                 Film 1 
               
               
                 Example 4 
                 Glycol Modified 
                 100 
                 18% 
                 2 types 
                 absent 
                 present 
                 Inorganic Multilayer 
                 20 
                 A 
               
               
                   
                 PET 
                   
                   
                   
                   
                   
                 Film 1 
               
               
                 Example 5 
                 Glycol Modified 
                 100 
                 18% 
                 2 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 24 
                 A 
               
               
                   
                 PET 
                   
                   
                   
                   
                   
                 Film 2 
               
               
                 Example 6 
                 Acrylic Resin 
                 100 
                 18% 
                 2 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 22 
                 A 
               
               
                   
                   
                   
                   
                   
                   
                   
                 Film 1 
               
               
                 Example 7 
                 Glycol Modified 
                 200 
                 18% 
                 2 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 28 
                 A 
               
               
                   
                 PET 
                   
                   
                   
                   
                   
                 Film 1 
               
               
                 Example 8 
                 Glycol Modified 
                 100 
                 30% 
                 2 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 35 
                 B 
               
               
                   
                 PET 
                   
                   
                   
                   
                   
                 Film 1 
               
               
                 Example 9 
                 Glycol Modified 
                 100 
                  3% 
                 2 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 42 
                 C 
               
               
                   
                 PET 
                   
                   
                   
                   
                   
                 Film 1 
               
               
                 Example 10 
                 Glycol Modified 
                 100 
                 10% 
                 2 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 35 
                 B 
               
               
                   
                 PET 
                   
                   
                   
                   
                   
                 Film 1 
               
               
                 Example 11 
                 Glycol Modified 
                 100 
                 20% 
                 2 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 18 
                 A 
               
               
                   
                 PET 
                   
                   
                   
                   
                   
                 Film 1 
               
               
                 Example 12 
                 Glycol Modified 
                 100 
                 45% 
                 2 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 7 
                 C 
               
               
                   
                 PET 
                   
                   
                   
                   
                   
                 Film 1 
               
               
                 Comparative 
                 Glycol Modified 
                 100 
                 absent (0%) 
                 2 types 
                 present 
                 absent 
                 White Ink Application 
                 50 
                 E 
               
               
                 Example 1 
                 PET 
               
               
                 Comparative 
                 Glycol Modified 
                 100 
                 absent (0%) 
                 2 types 
                 present 
                 absent 
                 Paper Affixing 
                 55 
                 E 
               
               
                 Example 2 
                 PET 
               
               
                 Comparative 
                 Glycol Modified 
                 100 
                 present (30%) 
                 2 types 
                 present 
                 absent 
                 — 
                 45 
                 D 
               
               
                 Example 3 
                 PET 
               
               
                 Comparative 
                 Glycol Modified 
                 100 
                 absent (0%) 
                 2 types 
                 present 
                 present 
                 Inorganic Multilayer 
                 49 
                 D 
               
               
                 Example 4 
                 PET 
                   
                   
                   
                   
                   
                 Film 
               
               
                   
               
            
           
         
       
     
     As can be seen from Table 1, stray light was generated in the lenticular lens and overlapping of images could not be suppressed in the following comparative examples: comparative example 1, in which the transparent-slit image strip was not provided and, white ink, instead of the anti-reflection layer, was applied to the back surface of the lenticular image; and comparative example 2, in which the transparent-slit image strip was not provided and, a sheet of paper, instead of the anti-reflection layer, was affixed to the back surface of the lenticular image. Therefore, compared with the Examples, the image viewability was low. 
     Likewise, compared with the Examples, the image viewability was low in the following comparative examples: comparative example 3, in which the transparent-slit image strip was provided but the anti-reflection layer was not provided; and comparative example 4, in which the anti-reflection layer was provided but the transparent-slit image strip was not provided. 
     The entire contents disclosed in JP2016-190293 filed on Sep. 28, 2016 is incorporated herein by reference. 
     All documents, patent applications, and technical standards mentioned in the present specification are incorporated herein by reference to the same extent as in the case where the individual documents, patent applications, and technical standards are specifically and individually described as being incorporated herein by reference.