JP7424131B2 - display body - Google Patents

Description

The present invention relates to a display body.

A display body attached to various articles to prevent counterfeiting of the articles can display, for example, a first image and a second image. When the viewing angle is the angle formed by the plane on which the display spreads and the plane that includes the viewer's line of sight, the display may display the first image at the first viewing angle, and display the first image at the second viewing angle. The image is displayed at a second viewing angle that is different from the first viewing angle. Each of the first image and the second image is formed by a concavo-convex structure having a plurality of pixels set without gaps with respect to the display body, when viewed from a viewpoint facing a plane on which the display body extends.

A first area, a second area, and a third area are set on the display body when viewed from a viewpoint corresponding to a plane on which the display body spreads. The first region includes a first pixel having an uneven structure for forming a first image, but does not include a second pixel having an uneven structure for forming a second image. The second region includes the second pixel but does not include the first pixel. On the other hand, the third region includes both the first pixel and the second pixel.

In the first area, in order to suppress variations in color in a part of the first image formed by the first area and color in a part of the first image formed by the third area, Among the pixels, only some of the pixels have a concavo-convex structure. Also in the second region, only some pixels have an uneven structure for the same reason as in the first region. In the first area and the second area, in order to suppress unevenness in the arrangement of pixels with an uneven structure, pixels with an uneven structure and pixels without an uneven structure are arranged in a checkerboard or striped pattern. (For example, see Patent Document 1).

International Publication No. 2019/182051

By the way, in each of the first region and the second region, pixels having a concavo-convex structure and pixels not having a concave-convex structure are arranged periodically, so if an optical effect is observed depending on the period in the pixel arrangement. There is. These optical effects are noise in contrast to the optical effects of each image that is originally required to be displayed on the display, and this causes the optical effects of each image that is originally required to be displayed on the display to be suppressed. This weakens the visibility of each image.

On the other hand, techniques for analyzing display bodies are being developed in order to develop display bodies with structures that are difficult to counterfeit. Techniques for manufacturing display bodies are also diversifying to realize structures that are difficult to counterfeit. However, improvements in display analysis technology have made it easier to analyze displays for the purpose of counterfeiting, and the diversification of display manufacturing technology has also made it easier to manufacture counterfeit products. It is said that Therefore, display bodies are required to have higher resistance against counterfeiting.

An object of the present invention is to provide a display body that can improve the visibility of images that can be displayed by the display body and that can improve resistance to counterfeiting.

A display body for solving the above problem is a display body including a relief layer in which an uneven structure is formed. The angle formed by the plane on which the relief layer spreads and the plane including the viewer's line of sight is the viewing angle, and the display body is capable of displaying the first image and the second image at mutually different viewing angles. . When viewed from a viewpoint facing a plane on which the relief layer spreads, the relief layer is lined with a plurality of pixels, and the plurality of pixels include a first pixel group, a second pixel group, and a third pixel group. . Each pixel of the first pixel group has a first uneven structure, each pixel of the second pixel group has a second uneven structure, and each pixel of the third pixel group has a first uneven structure. and the second uneven structure. The first image is formed by each pixel of the first pixel group and each pixel of the third pixel group. The second image is formed by each pixel of the second pixel group and each pixel of the third pixel group. Each pixel of the first pixel group has a sea-island structure having a plurality of island regions with at least one of non-periodic shape and arrangement in a plan view facing the plane on which the relief layer spreads, and has a sea region and a plurality of island regions. One of the island regions has the first uneven structure, and the other has the blank structure. The third pixel group records a machine-readable code.

According to the above configuration, since the pixels of the first pixel group have a sea-island structure in which island regions are arranged non-periodically, noise based on the periodicity in the arrangement of the first pixel group is suppressed, and as a result, the noise in the first image is suppressed. Visibility is improved. Further, since it is possible to determine the authenticity of the display body using the code recorded by the third pixel group, it is possible to increase the resistance of the display body against forgery.

In the above display, in each pixel included in the first pixel group, the shape of the plurality of island regions is different from the shape in the other pixels, or the arrangement of the plurality of island regions is different from that in the other pixels. The arrangement of the plurality of island regions is different from the arrangement of the plurality of island regions in . According to this configuration, noise based on periodicity in the pixel arrangement is more reliably suppressed, and the visibility of the first image is more reliably improved.

In the display, the shape and arrangement of the plurality of island regions in each pixel included in the first pixel group may be the same as the shape and arrangement of the plurality of island regions in the other pixels.

According to the above configuration, it is possible to suppress noise based on periodicity in the arrangement of each pixel belonging to the first pixel group, and to facilitate the manufacturing of the display by facilitating the design of the first pixel group.

In the display, the first uneven structure reflects light included in the visible light region in the specular reflection direction by guided mode resonance in the first uneven structure, and the island region has the first uneven structure; The sea area may have the blank structure.

According to the above configuration, since the area in which the incident light incident on the first uneven structure propagates while being subjected to multiple reflections is guaranteed by the area of the island region, the first uneven structure allows the reflected light due to waveguide mode resonance to color intensity increases.

In the display, the blank structure reflects light in a regular reflection direction, and the ratio of the total area of the first uneven structure included in the first pixel group to the total area of the first pixel group is The ratio may be larger than the ratio of the total area of the first uneven structure included in the third pixel group to the total area of the pixel group.

According to the above configuration, in the first pixel group, even if the optical effect of the light reflected by the island region is weakened by the light reflected by the blank structure, the area ratio of the first uneven structure is increased. The unevenness of shading in the first image that occurs between the first pixel group and the third pixel group is suppressed.

In the display, the blank structure has an uneven structure, and the uneven structure of the blank structure has a wavy shape in a cross section perpendicular to a plane in which the display spreads, and the uneven structure of the blank structure has The period is smaller than the shortest wavelength of visible light, and the height of the uneven structure of the blank structure is larger than the period, so that the blank structure does not transmit light incident on the blank structure. good.

According to the above configuration, the light reflected by the blank structure does not affect the light reflected by the first concavo-convex structure, so that unevenness in density in the first image caused by the light reflected by the blank structure is suppressed.

In the display, each pixel of the second pixel group has a sea-island structure in which a plurality of island regions have an aperiodic shape and arrangement in the planar view, and one of the sea region and the island region has a non-periodic shape and arrangement. It may have a second uneven structure and the other may have a blank structure.

According to the above configuration, since the pixels of the second pixel group have a sea-island structure in which island regions are arranged non-periodically, noise based on periodicity in the arrangement of the second pixel group is suppressed, and as a result, the noise in the second image is suppressed. Visibility is improved.

In the above display, each pixel of the third pixel group has a sea-island structure having a plurality of island regions having at least one of a non-periodic shape and arrangement in the planar view, and the island region is the third pixel group. The sea area may have a blank structure, including an island region having a first uneven structure and an island region having the second uneven structure.

According to the above configuration, in the third pixel group, both the first uneven structure and the second uneven structure are arranged irregularly, so that the portion of the first image displayed by the third pixel group, , the visibility of the portion of the second image displayed by the third pixel group is enhanced.

In the display, at least some of the pixels included in the third pixel group are codes associated with the arrangement of the island region and the sea region of the sea-island structure that the third pixel group has. , a machine-readable code may be recorded.

According to the above configuration, since the third pixel group records a machine-readable code, it is possible to determine the authenticity of the display body using the code. This makes it possible to determine the authenticity of the display using both the image that the display can display and the code recorded by the display. Therefore, compared to the case where the display does not record a code, it is possible to increase the resistance of the display to counterfeiting.

According to the present invention, the visibility of images that can be displayed by a display body can be improved, and the resistance against forgery can be increased.

FIG. 2 is a plan view showing the outer shape of a pixel group set on a display body of one embodiment together with the outer shape of the display body. FIG. 2 is a perspective view showing the display shown in FIG. 1 together with the display showing a first observation angle at which a first image is displayed and a second observation angle at which a second image is displayed. FIG. 2 is a plan view showing the first pixel group shown in FIG. 1 and a partially enlarged configuration of the first pixel group. FIG. 3 is a plan view showing an example of a sea-island structure in pixels included in the first pixel group. FIG. 7 is a plan view showing another example of a sea-island structure in pixels included in the first pixel group. FIG. 3 is a cross-sectional view showing the shape of the first uneven structure. FIG. 3 is a schematic diagram for explaining the relationship between the direction in which the first uneven structure extends and the direction of the observer's line of sight. FIG. 3 is a schematic diagram for explaining the relationship between the direction in which the first uneven structure extends and the direction of the observer's line of sight. FIG. 3 is a cross-sectional view showing the shapes of a first uneven structure and a blank structure. FIG. 3 is a cross-sectional view showing the shapes of a first uneven structure and a blank structure. The perspective view which shows an example of the uneven|corrugated structure which a blank structure has. The perspective view which shows another example of the uneven|corrugated structure which a blank structure has. FIG. 3 is a cross-sectional view showing the shapes of a first uneven structure and a blank structure. FIG. 2 is a plan view showing the second pixel group shown in FIG. 1 and a partially enlarged configuration of the second pixel group. FIG. 7 is a plan view showing an example of a sea-island structure in pixels included in the second pixel group. FIG. 7 is a plan view showing another example of a sea-island structure in pixels included in the second pixel group. FIG. 3 is a cross-sectional view showing the shape of a second uneven structure. A graph showing the relationship between the density of the second uneven structure and the diffraction angle. The figure which shows the spectrum of the reflected light in nine display bodies with mutually different r values. The figure which shows the color of the light reflected by nine display bodies in an xy chromaticity diagram. FIG. 3 is a cross-sectional view showing the shapes of a first uneven structure and a second uneven structure. FIG. 2 is a plan view showing a third pixel group shown in FIG. 1 and a partially enlarged configuration of the third pixel group. FIG. 3 is a plan view showing a first example of arrangement of sub-pixels in pixels included in a third pixel group. FIG. 7 is a plan view showing a second example of arrangement of sub-pixels in pixels included in the third pixel group. FIG. 7 is a plan view showing a sea-island structure in pixels included in the third pixel group. FIG. 7 is a plan view showing a third example of arrangement of sub-pixels in pixels included in a third pixel group. FIG. 7 is a plan view for explaining the third image. FIG. 7 is a plan view for explaining the third image. FIG. 7 is a plan view for explaining the third image. FIG. 3 is a schematic diagram for explaining a method for determining authenticity of a display body. 1 is a flowchart for explaining the steps in a method for determining authenticity of a display object. FIG. 7 is a plan view showing the arrangement of island regions and sea regions in a sea-island structure of a third pixel group in a modified example. A table for explaining codes associated with a third pixel group. FIG. 3 is a diagram showing the relationship between the arrangement of island areas and sea areas in pixels and codes recorded in pixels. FIG. 3 is a plan view showing the relationship between the center position of a pixel and the center position of an island region. FIG. 7 is a plan view showing another example of the shape of the island region. The figure which shows the example of the code recorded by several pixels. The figure which shows an example of the determination pixel which a 3rd pixel group has. The figure which shows the other example of the determination pixel which a 3rd pixel group has. FIG. 7 is a plan view showing an example of the structure of designation pixels included in the third pixel group. FIG. 7 is a plan view showing another example of the structure of designation pixels included in the third pixel group. FIG. 7 is a diagram illustrating a processing procedure in a method for determining authenticity of a display body using a code recorded in a third pixel group.

One embodiment of the display will be described with reference to FIGS. 1 to 31.
[Display]
As shown in FIG. 1, the display body 10 includes a relief layer 10R in which an uneven structure is formed. When viewed from a viewpoint facing the plane on which the relief layer 10R extends, the relief layer 10R is lined with a plurality of pixels 10P. In the plurality of pixels 10P, each pixel 10P is adjacent to each other. The plurality of pixels 10P include a first pixel group PG1, a second pixel group PG2, and a third pixel group PG3.

The display body 10 is capable of displaying a first image and a second image. The first pixel group PG1 is formed from pixels 10P for forming the first image. The second pixel group PG2 is formed from pixels 10P for forming a second image. On the other hand, each pixel 10P included in the third pixel group PG3 is a pixel for forming the first image and a pixel for forming the second image.

Each pixel 10P of the first pixel group PG1 has a first uneven structure. Typically, each pixel 10P of the first pixel group PG1 does not have the second uneven structure. Each pixel 10P of the second pixel group PG2 has a second uneven structure. Typically, each pixel 10P of the second pixel group PG2 does not have the first uneven structure. Each pixel 10P of the third pixel group PG3 includes both the first uneven structure and the second uneven structure. The first image is formed by each pixel of the first pixel group PG1 and each pixel of the third pixel group PG3. The second image is formed by each pixel of the second pixel group PG2 and each pixel of the third pixel group PG3.

FIG. 2 is a diagram for explaining a first image and a second image that can be displayed by the display body 10. In FIG. 2, the first image and the second image are shown in one figure for convenience of explanation. Note that in this embodiment, the display 10 actually displays the first image within a predetermined viewing angle range, and displays the second image within a predetermined viewing angle range. The viewing angle range in which the first image is displayed may or may not include a part of the viewing angle range in which the second image is displayed.

As shown in FIG. 2, the angle formed by the plane on which the relief layer 10R spreads and the plane including the viewing direction of the observer OB is the observation angle θOB. The display body 10 can display the first image PIC1 and the second image PIC2 at mutually different viewing angles θOB. In this embodiment, the display 10 displays the first image PIC1 at the first observation angle θOB1 and displays the second image PIC2 at the second observation angle θOB2. The second observation angle θOB2 is a different angle from the first observation angle θOB1.

In the display body 10, the first uneven structure for forming the first image PIC1 reflects the light from the light source LS at a first reflection angle θR1. On the other hand, the second uneven structure for forming the second image PIC2 reflects the light from the light source LS at a second reflection angle θR2. The second reflection angle θR2 is a different angle from the first reflection angle θR1.

The shape of the first image PIC1 is approximately equal to the shape formed by the outer shape of the first pixel group PG1 and the outer shape of the third pixel group PG3. The shape of the second image PIC2 is approximately equal to the shape formed by the outer shape of the second pixel group PG2 and the outer shape of the third pixel group PG3. Hereinafter, the structure of each pixel group PG1, PG2, PG3 will be explained in order with reference to the drawings.

[First pixel group]
The first pixel group PG1 will be described with reference to FIGS. 3 to 13.
As shown in FIG. 3, the first pixel group PG1 includes a plurality of pixels 10P. The plurality of pixels 10P are lined up without gaps. In this embodiment, each pixel 10P has a square shape. The first pixel group PG1 includes a first pixel PG11 and a second pixel PG12.

The plurality of pixels 10P are lined up along one direction, the x direction, and the y direction, which is a direction perpendicular to the x direction. The size of the pixel 10P along the x direction is 300 μm or less, preferably 100 μm or less. Further, the size of the pixel 10P along the y direction is 300 μm or less, preferably 100 μm or less. By including the pixels 10P in these ranges in the x and y directions, each pixel 10P can have a size that is less than the resolution limit of the observer OB. Note that each pixel 10P may have a shape other than a square shape. For example, each pixel 10P may have a polygonal shape other than a square shape. The polygonal shape other than the square shape is, for example, a triangular shape or an octagonal shape.

FIG. 4 enlarges and schematically shows the first pixel PG11.
As shown in FIG. 4, the first pixel PG11 of the first pixel group PG1 has a sea-island structure in which a plurality of island regions PG11a have an aperiodic shape and arrangement in a plan view facing the plane in which the relief layer 10R spreads. have. In the sea-island structure, a portion surrounding the plurality of island regions PG11a is a sea region PG11b. One of the sea region PG11b and the island region PG11a has a first uneven structure, and the other has a blank structure. As a result, since the pixel 10P of the first pixel group PG1 has a sea-island structure in which the island regions PG11a and PG12a are arranged non-periodically, the optical effect based on the periodicity in the arrangement of the first pixel group PG1, that is, the noise, is suppressed. As a result, the visibility of the first image PIC1 is improved. Note that since the visibility of the first image PIC1 is improved, the display 10 can give the viewer of the display 10 the impression that the display 10 has a sophisticated appearance.

Note that the aperiodic may be aperiodic in both the first direction and the second direction orthogonal to the first direction. At this time, the frequency components obtained by two-dimensional Fourier transform of each pixel group do not have discrete peaks. More precisely, a frequency component obtained by two-dimensional Fourier transform of a group of pixels within 1 mm square can be considered aperiodic if it does not have discrete peaks. Furthermore, a case where the distribution of the reflected light of the laser light incident on the display body 10 does not have a discrete peak other than the zero-order light may be considered non-periodic. Note that the wavelength of the laser light may be, for example, 633 nm or 532 nm.

In this embodiment, each island region PG11a has a rectangular shape. While the plurality of island regions PG11a each have a rectangular shape, the width and length of each island region PG11a are aperiodic. In the plurality of island regions PG11a, both the x-direction dimension and the y-direction dimension may be aperiodic, or either the x-direction dimension or the y-direction dimension may be aperiodic. good. Note that it is more preferable that at least one of the width and length of each island region PG11a has randomness.

Further, the plurality of island regions PG11a are arranged aperiodically within each pixel 10P in a plan view facing the plane in which the relief layer 10R extends. For example, the plurality of island regions PG11a may be arranged within one pixel 10P so that both the spacing in the x direction and the spacing in the y direction are aperiodic, or the spacing in the x direction and the spacing in the y direction are aperiodic. Either one of the intervals may be arranged to be non-periodic. Note that it is more preferable that the plurality of island regions PG11a are arranged within one pixel 10P so that at least one of the intervals in the x direction and the intervals in the y direction has randomness.

FIG. 5 enlarges and schematically shows the second pixel PG12.
As shown in FIG. 5, in the second pixel PG12, as in the first pixel PG11, in a plan view facing the plane in which the relief layer 10R spreads, a plurality of island regions PG12a are sea islands having an aperiodic shape and arrangement. It has a structure. In the sea-island structure, a portion surrounding the plurality of island regions PG12a is a sea region PG12b. One of the sea region PG12b and the island region PG12a has a first uneven structure, and the other has a blank structure.

In this embodiment, each island region PG12a has a rectangular shape. While the plurality of island regions PG12a each have a rectangular shape, the width and length of each island region PG12a are aperiodic. In the plurality of island regions PG12a, both the x-direction dimension and the y-direction dimension may be aperiodic, or either the x-direction dimension or the y-direction dimension may be aperiodic. good. It is more preferable that at least one of the width and length of each island region PG12a has randomness.

Furthermore, the plurality of island regions PG12a are arranged aperiodically within each pixel 10P in a plan view facing the plane in which the relief layer 10R extends. For example, the plurality of island regions PG12a may be arranged within one pixel 10P so that both the spacing in the x direction and the spacing in the y direction are aperiodic, or the spacing in the x direction and the spacing in the y direction are aperiodic. Either one of the intervals may be arranged to be non-periodic. Note that it is more preferable that the plurality of island regions PG12a are arranged within one pixel 10P so that at least one of the intervals in the x direction and the intervals in the y direction has randomness.

In this embodiment, in each pixel 10P included in the first pixel group PG1, the shape and arrangement of the plurality of island regions PG11a and PG12a are different from the shape and arrangement of the plurality of island regions PG11a and PG12a in other pixels 10P. Therefore, the shape and arrangement of the island region PG12a in the second pixel PG12 are different from the shape and arrangement of the island region PG11a in the first pixel PG11. Thereby, noise based on periodicity in the arrangement of the first pixel group PG1 is more reliably suppressed, and the visibility of the first image PIC1 is more reliably improved.

The first uneven structure and blank structure of the sea-island structure will be described in more detail with reference to FIGS. 6 to 12. FIG. 6 shows the shape of the first uneven structure in a cross section perpendicular to the plane in which the relief layer 10R spreads. FIG. 9 shows an example of the shapes of the first uneven structure and the blank structure in a cross section perpendicular to the plane in which the relief layer 10R spreads. FIG. 10 shows another example of the shape of the first uneven structure and the blank structure in a cross section perpendicular to the plane in which the relief layer 10R extends. In addition, in FIGS. 6, 9, and 10, for convenience of explanation and illustration, the angle of the incident light that enters each structure and the angle of the reflected light that is reflected by each structure are shown for each of the incident light and reflected light. Only the angle at which the intensity is highest is shown. Furthermore, in FIGS. 6, 9, and 10, for convenience of illustration, the direction in which the uneven structure extends is orthogonal to the plane containing the incident light and the reflected light. The two may be parallel, perpendicular, or intersect at an angle other than parallel. As will be described later, from the viewpoint that the diffracted light due to the periodicity of the uneven structure, in other words noise, is not emitted in the direction of the observer, the direction in which the uneven structure extends is parallel to the plane containing the incident light and the reflected light. It is preferable that

As shown in FIG. 6, the first uneven structure UE1 of this embodiment has a wave shape that repeats periodically along one direction in a cross section perpendicular to the plane in which the relief layer 10R spreads. The first uneven structure UE1 can have a sinusoidal shape. The period P1 of the first uneven structure UE1 is equal to or less than a visible wavelength. The period P1 of the first uneven structure UE1 is, for example, 200 nm or more and 500 nm or less. It is preferable that the height H1 of the first uneven structure UE1 is, for example, less than 200 nm. Note that the first uneven structure UE1 has a convex surface including the top and a concave surface including the bottom. The period P1 of the first uneven structure UE1 is the distance between two mutually adjacent tops in the first uneven structure UE1. The height H1 of the first uneven structure UE1 is the distance between the top and bottom of the first uneven structure UE1.

In this embodiment, the first uneven structure UE1 reflects light included in the visible light region in the specular reflection direction by waveguide mode resonance in the first uneven structure UE1. In this case, it is preferable that the island regions PG11a and PG12a have the first uneven structure UE1. As a result, the area in which the incident light incident on the first uneven structure UE1 propagates while being subjected to multiple reflections is guaranteed by the area of the island regions PG11a and PG12a. The color intensity of reflected light increases.

Note that the propagation distance of the incident light contributes to the intensity of the light reflected in the specular reflection direction. The intensity of light reflected in the specular reflection direction tends to increase as the propagation distance of the incident light increases. From the viewpoint that the light reflected in the specular reflection direction has sufficient intensity, it is preferable that the length of one side of the island region is 50 μm or more.

When the incident light IL enters the first uneven structure UE1, reflection of the diffracted light is suppressed against a plane that is perpendicular to the plane in which the relief layer 10R spreads and that includes the incident light, while light due to waveguide mode resonance A reflection occurs. In waveguide mode resonance, light in a specific wavelength range propagates within an optical device while undergoing multiple reflections, causing resonance, and as a result, the light in the wavelength range is reflected in the optical device as reflected light RL with high intensity. This is a reflected phenomenon. The first uneven structure UE1 reflects the reflected light RL at a first reflection angle θR1, which is a regular reflection direction.

When the first uneven structure UE1 specularly reflects visible light having a specific wavelength by guided mode resonance, the relief layer 10R has a three-layer structure at least in a portion corresponding to the first uneven structure UE1. . The three-layer structure is formed from a first low index layer, a high index layer, and a second low index layer. In the three-layer structure, the high refractive index layer is sandwiched between the first low refractive layer and the second low refractive layer. Each layer has optical transparency, and the refractive index of the high refractive layer is higher than the refractive index of the first low refractive layer and the second low refractive layer. The refractive index of the first low refractive layer may be equal to the refractive index of the second low refractive layer, or may be different from the refractive index of the second low refractive layer.

In the display body 10, a part of the light diffracted by the high refractive layer among the incident light incident on the display body 10 is transmitted to the boundary between the first low refractive layer and the high refractive layer and between the high refractive layer and the first refractive layer. It propagates through the high refractive index layer while being totally reflected at the boundary with the two low refractive index layers. Such light propagation is achieved because the second refractive index n2 of the high refractive layer is higher than the first refractive index n1 of the first low refractive layer and higher than the third refractive index n3 of the second low refractive layer. arise. Of the incident light, only light with a wavelength that satisfies the waveguide propagation conditions described below propagates through the high refractive index layer as waveguide light, and as a result of propagation, is displayed as reflected light with high brightness. reflected at the body 10. The reflected light is reflected in the direction of specular reflection. On the other hand, light having a wavelength that does not satisfy the propagation conditions exits the display body as transmitted light that passes through the display body.

Viewed from the light propagating inside the display body 10, the display body 10 has a part of the high refractive index layer and the first low refractive layer or the second low refractive layer in the direction in which the concave surface and the convex surface of the high refractive index layer are lined up. It has a structure in which some parts are arranged alternately. That is, in the direction in which the concave surface and the convex surface are lined up, the high bending part and the low bending part are arranged alternately.

The propagation conditions are determined by the following equation (1 ) can be expressed by equation (6).

k = 2π/λ... Formula (4)
K = 2π/d... Formula (5)
β = (2π/λ)・n _eff ... Formula (6)

In equation (3), the diffraction order m is an integer. Furthermore, in equation (3), the propagation constant β of the waveguide layer, that is, the high refractive layer, depends on the wavelength λ of the incident light and the effective refractive index n _eff of the high refractive layer. Equation (1) shows the effective refractive index n _eff of the high refractive index layer for TE waves, and equation (2) shows the effective refractive index n _eff of the high refractive layer for TM waves. In the effective refractive index n _eff of the high refractive layer, when the period d of the uneven surface is shorter than the wavelength λ of the incident light, the effective refractive index n _eff for TE waves and the effective refractive index n _eff for TM waves are different from each other. .

Each effective refractive index n _eff is determined by the occupation rate of the high refractive layer in the period d. When the width of the high refractive index layer is set to a and the width of the first low refractive layer or the second low refractive layer is set to b, the occupation rate of the high refractive layer in the period d is the ratio of the width a to the period d. The occupation rate of the first low refractive index layer or the second low refractive index layer in the period d is the ratio of the width b to the period d.

The waveguide conditions that satisfy the above equations (1) to (6) can be expressed by the following equations.
n _eff >n1, n3... Formula (7)
λ>d... Formula (8)

As described above, since the effective refractive index n _eff is determined by the occupation ratio (a/d) of the high refractive layer in the period d, it is possible to derive the following relationship.
n2>n1, n3... Formula (9)

Further, using the effective refractive index n _eff , it is possible to determine the wavelength of light guided in the display body 10 and the reflectance of light having the wavelength. That is, by adjusting the effective refractive index n _eff , it is possible to reflect chromatic light with high brightness onto the display body 10 using guided mode resonance.

Furthermore, as is clear from the above formula, the effective refractive index n _eff and the propagation constant β are determined by the parameters included in the formula for deriving them, that is, the first refractive index n1 to the third refractive index n3, the period d, and , by changing the occupancy F, it is possible to control the wavelength and reflectance of light reflected by guided mode resonance. Furthermore, the light reflected by waveguide mode resonance also depends on the angle of the incident light incident on the display 10. Therefore, the display body 10 using guided mode resonance is suitable for determining the light reflected by the display body 10 by machine reading.

Further, the larger the difference between the effective refractive index n _eff and the first refractive index n1 or the difference between the effective refractive index n _eff and the third refractive index n3, the higher the reflectance of light reflected by guided mode resonance. Become. That is, the larger the occupation rate F of the high refractive layer, the higher the light reflectance can be. In this way, the reflectance of light is determined according to the difference between the effective refractive index n _eff and the first refractive index n1 and the difference between the effective refractive index n _eff and the third refractive index n3. Therefore, when the material that can be used for the first low refractive index layer and the second low refractive index layer, in other words, the refractive index is fixed, the shape of the uneven surface in the first low refractive layer and the high refractive layer Controlling the effective refractive index n _eff by the thickness of the display body 10 is useful for diversifying the wavelengths of light reflected by the display body 10 .

7 and 8 show the relationship between the direction in which the concave and convex surfaces of the first uneven structure UE1 extend and the line of sight direction of the observer OB. In FIGS. 7 and 8, the directions in which the concave and convex surfaces extend are schematically shown by solid lines drawn on the display 10.

As shown in FIG. 7, the concave surface and the convex surface of the first uneven structure UE1 extend in one direction. In the example shown in FIG. 7, the concave surface and the convex surface extend along the left-right direction of the page. On the other hand, the projection direction in which the line-of-sight direction DOB of the observer OB is projected onto the plane on which the display body 10 spreads is the left-right direction of the paper surface. The projection direction is parallel to the direction in which the concave and convex surfaces extend. That is, the first uneven structure UE1 is oriented vertically with respect to the observer OB.

In the example shown in FIG. 8, the concave surface and the convex surface extend along the vertical direction of the page. On the other hand, the projection direction in which the line-of-sight direction DOB of the observer OB is projected onto the plane on which the display body 10 extends is the left-right direction of the paper surface. The projection direction is perpendicular to the direction in which the concave and convex surfaces extend. That is, the first uneven structure UE1 is oriented laterally with respect to the observer OB.

The reflected light RL of the display body 10 may include first-order diffracted light. The first-order diffracted light is reflected on a plane that is perpendicular to the direction in which the concave and convex surfaces extend and is perpendicular to the plane in which the display body 10 extends. Therefore, when the first concavo-convex structure UE1 is oriented sideways with respect to the observer OB, the observer OB may visually recognize the first-order diffracted light reflected by the display 10. Furthermore, the observer OB may mistakenly recognize the first-order diffracted light that he/she visually recognized as zero-order diffracted light, that is, reflected light due to waveguide mode resonance. On the other hand, when the first concavo-convex structure UE1 is oriented vertically with respect to the observer OB, it is possible to reduce the possibility that the observer OB misidentifies the first-order diffracted light as the zero-order diffracted light. be.

The blank structure of the sea-island structure has an optical effect different from the optical effect of the first uneven structure UE1. The optical effect that the first uneven structure UE1 has is an optical effect for displaying the first image PIC1. On the other hand, the optical effect of the blank structure does not contribute to the display of the first image PIC1. The blank structure includes light reflected from the first pixel group PG1, which is the color of the light for displaying the first image PIC1, and light reflected from the third pixel group PG3, which is the color of the light used to display the first image PIC1. This structure is designed to suppress variations in the color of the light used to display the images. However, the light reflected by the blank structure may be observed by the observer OB together with the light reflected by the first uneven structure UE1. That is, the reflection angle of the reflected light in the blank structure may be included in the reflection angle θR1 of the reflected light RL reflected by the first uneven structure UE1.

In the example shown in FIG. 9, the blank structure BL is substantially flat. The blank structure BL is flatter than the first uneven structure UE1. In the blank structure BL, the height of the unevenness may be, for example, 40 nm or less. As the roughness of the blank structure BL increases, the blank structure BL has a tendency to scatter the light incident on the blank structure BL over a wide range. On the other hand, as the surface roughness of the blank structure BL becomes lower, the blank structure BL tends to specularly reflect, that is, regularly reflect, the light incident on the blank structure BL.

When the blank structure BL is flat, regardless of whether the surface roughness of the blank structure BL is high or low, a considerable amount of light incident on the blank structure BL is specularly reflected. Thereby, the blank structure BL reflects the light at a reflection angle θRB equal to the incident angle of the incident light IL. The reflection angle θRB of the blank structure BL is equal to the first reflection angle θR1 of the first uneven structure UE1. Therefore, when the observer OB observes the display body 10, he/she observes the light reflected by the first uneven structure UE1 together with the light reflected by the blank structure BL.

Since the blank structure BL does not separate the incident light IL when reflecting the incident light IL, the wavelength of the light reflected by the blank structure BL depends on the wavelength of the light emitted by the light source LS. When the light source LS is the sun, a fluorescent lamp, a white LED, or the like, the light reflected by the blank structure BL has white color because it is a mixture of lights having different wavelengths. As a result, when the first uneven structure UE1 specularly reflects visible light having a specific wavelength as in the present embodiment, the color of the light reflected by the first uneven structure UE1 is different from that of the blank structure BL. is weakened by the reflected light, and as a result, the color of the light reflected by the first uneven structure UE1 becomes lighter.

In this case, the ratio (TAU1/TA1) of the total area (TAU1) of the first uneven structure UE1 included in the first pixel group PG1 to the total area (TA1) of the first pixel group PG1 is The ratio (TAU3/TA3) of the total area (TAU3) of the first uneven structure UE1 included in the third pixel group PG3 to the total area (TA3) of the third pixel group PG3 is possible. Thereby, in the first pixel group PG1, even if the optical effect of the light reflected by the island regions PG11a and PG12a is weakened by the light reflected by the blank structure BL, the area ratio of the first uneven structure UE1 can be increased. As a result, unevenness in shading in the first image PIC1 is suppressed.

In the example shown in FIG. 10, the blank structure BL has an uneven structure UEB. The uneven structure UEB of the blank structure BL has a wavy shape in a cross section perpendicular to the plane in which the display body 10 extends. The period PB of the uneven structure UEB of the blank structure BL is less than the visible wavelength, and the height HB of the uneven structure is larger than the period PB, so that the blank structure BL transmits the light incident on the blank structure BL. Note that the period PB of the uneven structure UEB can be 200 nm or more and 500 nm or less, and is preferably smaller than the shortest wavelength of visible light, that is, 400 nm or less.

The uneven structure UEB can have a sinusoidal shape. In the uneven structure UEB, the period PB can be 200 nm or more and 500 nm or less. The height HB of the uneven structure UEB is higher than the height H1 of the first uneven structure UE1. The aspect ratio of the uneven structure UEB is preferably 0.5 or more and 3.7 or less, and more preferably 1 or more from the viewpoint of suppressing the reflection of light described below. The aspect ratio of the uneven structure UEB is the ratio (HB/PB) of the height (HB) of the uneven structure UEB to the period (PB) of the uneven structure UEB. The height HB of the uneven structure UEB may be, for example, 200 nm or more and 750 nm or less.

In such a blank structure BL, fine irregularities with a high aspect ratio are repeated, so that in a cross section parallel to the plane in which the relief layer 10R spreads from the top to the bottom of the uneven structure UEB, the refractive index at the cross section is It can be considered to change continuously. Note that the refractive index of the cross section is determined by a part of the uneven structure UEB included in the cross section and the surrounding structure of the uneven structure UEB. The surrounding structure of the uneven structure UEB can be, for example, air or resin covering the uneven structure UEB. Therefore, reflection of light at the interface between the uneven structure UEB and surrounding structures of the uneven structure UEB is suppressed. Therefore, most of the light incident on the blank structure BL is transmitted through the blank structure BL.

According to such a structure, the light reflected by the blank structure BL does not affect the light reflected by the first concavo-convex structure UE1, so that unevenness in shading in the first image PIC1 caused by the light reflected by the blank structure BL can be suppressed. . Therefore, in the first pixel group PG1, in order to suppress unevenness in shading due to light reflected by the blank structure BL, the area of the first uneven structure UE1 and the area of the blank structure BL are set based on the third pixel group PG3. No need to adjust. In such a structure, the area of the first uneven structure UE1 per unit area in the first pixel group PG1 may be equal to the area of the first uneven structure UE1 per unit area in the third pixel group PG3. Therefore, the design of the first pixel group PG1 is easy.

FIG. 11 is a perspective view showing an example of the uneven structure UEB that the blank structure BL has, and FIG. 12 is a perspective view showing another example of the uneven structure UEB that the blank structure BL has.
As shown in FIG. 11, the uneven structure UEB may be a single grating. In this case, the uneven structure UEB has a shape extending along one direction, that is, the extension direction. In a cross section perpendicular to the plane in which the display body 10 spreads and perpendicular to the direction in which the concavo-convex structure UEB extends, the concavo-convex structure UEB has a wavy shape, and the wavy shapes are continuous along the extending direction.

As shown in FIG. 12, the uneven structure UEB may be a cross grating. In this case, the uneven structure UEB can have a plurality of convex portions lined up along the first direction and the second direction orthogonal to the first direction. The uneven structure UEB may have a plurality of concave portions lined up along the first direction and the second direction. The uneven structure UEB has a first period PB1 in the first direction and a second period PB2 in the second direction. The first period PB1 and the second period PB2 may be the same or different.

Note that when the uneven structure UEB is a single grating, the uneven structure UEB is preferably oriented vertically with respect to the observer OB for the same reason as the first uneven structure UE1. On the other hand, when the uneven structure UEB is a cross grating, the uneven structure UEB is arranged neither vertically nor horizontally with respect to the observer OB, that is, aligned along a direction crossing the vertically or horizontally. It is preferable. As with the first uneven structure UE1, this prevents the viewer OB from visually recognizing the diffracted light reflected by the uneven structure UEB.

As shown in FIG. 13, the display body 10 may include a reflective layer 10RF that covers the relief layer 10R. The reflective layer 10RF is a layer having a higher refractive index than the surface of the relief layer 10R. The surface of the relief layer 10R is the surface on which the reflective layer 10RF is located. The reflective layer 10RF is formed of a transparent material. The transparent material may be, for example, TiO ₂ , ZnS, and SiO ₂ . The reflective layer 10RF may have a single layer structure or a multilayer structure. When the reflective layer 10RF has a multilayer structure, the reflective layer 10RF can have a first layer made of a transparent material and a second layer located on the first layer and made of metal. . The metal may be aluminum, for example. Note that the thickness of the second layer is preferably less than 20 nm. Thereby, even if the reflective layer 10RF has a second layer made of metal, the viewer OB can be made to recognize that the display body 10 is transparent.

When the blank structure BL has the uneven structure UEB described with reference to FIG. 11 and FIG. and a second part RF2 located on the structure UEB. In the reflective layer 10RF, the thickness of the first portion RF1 may be thicker than the thickness of the second portion RF2. Thereby, while increasing the intensity of the reflected light in the first portion RF1, it is possible to suppress the intensity of the reflected light in the second portion RF2 from increasing.

Note that from the viewpoint of suppressing reflection on the uneven structure UEB of the blank structure BL, it is preferable that the display body 10 does not have a reflective layer that covers the uneven structure UEB. That is, it is preferable that the reflective layer 10RF does not have the second portion RF2. Such a reflective layer 10RF is formed by, for example, forming a reflective layer that covers the first uneven structure UE1 and the uneven structure UEB of the blank structure BL, and then removing a portion of the reflective layer that covers the uneven structure UEB. . However, when the aspect ratio of the uneven structure UEB is higher than the aspect ratio of the first uneven structure UE1, the thickness of the second portion RF2 becomes thinner than the thickness of the first portion RF1 in the reflective layer 10RF. This makes it possible to suppress reflection at the second portion RF2.

[Second pixel group]
The second pixel group PG2 will be described with reference to FIGS. 14 to 21.
As shown in FIG. 14, the second pixel group PG2 includes a plurality of pixels 10P. The plurality of pixels 10P are lined up without gaps. In this embodiment, each pixel 10P has a square shape. It is preferable that the pixels 10P included in the second pixel group PG2 have the same shape and size as the pixels 10P included in the first pixel group PG1. The second pixel group PG2 includes a first pixel PG21 and a second pixel PG22.

The pixel 10P included in the second pixel group PG2 may have a polygonal shape other than a square, similar to the pixel 10P included in the first pixel group PG1.
FIG. 15 enlarges and schematically shows the first pixel PG21. For convenience of illustration, the shape and arrangement of the island region in the first pixel PG21 of the second pixel group PG2 are the same as the shape and arrangement of the island region PG11a in the first pixel PG11 of the first pixel group PG1. In each of the first pixels PG11 and PG21, the shape and arrangement of the island regions may be the same or different.

As shown in FIG. 15, the first pixel PG21 of the second pixel group PG2 has a sea-island structure in which a plurality of island regions PG21a have an aperiodic shape and arrangement in a plan view facing the plane in which the relief layer 10R spreads. have. In the sea-island structure, a portion surrounding the plurality of island regions PG21a is a sea region PG21b. One of the sea region PG21b and the island region PG21a has a second uneven structure, and the other has a blank structure. Since the pixel 10P of the second pixel group PG2 has a sea-island structure in which the island regions PG21a and PG22a are arranged aperiodically, noise based on periodicity in the arrangement of the second pixel group PG2 is suppressed, and as a result, the second image PIC2 visibility is increased. Note that since the visibility of the second image PIC2 is improved, the display 10 can give the viewer of the display 10 the impression that the display 10 has a sophisticated appearance.

In this embodiment, each island region PG21a has a rectangular shape. While the plurality of island regions PG21a each have a rectangular shape, the width and length of each island region PG21a are aperiodic. In the plurality of island regions PG21a, both the x-direction dimension and the y-direction dimension may be aperiodic, or either the x-direction dimension or the y-direction dimension may be aperiodic. good. In addition, it is more preferable that at least one of the width and length of each island region PG21a has randomness.

Further, the plurality of island regions PG21a are arranged aperiodically within each pixel 10P in a plan view facing the plane in which the relief layer 10R extends. For example, the plurality of island regions PG21a may be arranged within one pixel 10P so that both the spacing in the x direction and the spacing in the y direction are aperiodic, or the spacing in the x direction and the spacing in the y direction are aperiodic. Either one of the intervals may be arranged to be non-periodic. Note that it is more preferable that the plurality of island regions PG21a are arranged within one pixel 10P so that at least one of the intervals in the x direction and the intervals in the y direction has randomness.

FIG. 16 enlarges and schematically shows the second pixel PG22. For convenience of illustration, the shape and arrangement of the island region in the second pixel PG22 of the second pixel group PG2 are the same as the shape and arrangement of the island region PG12a in the second pixel PG12 of the first pixel group PG1. In each of the second pixels PG12 and PG22, the shape and arrangement of the island regions may be the same or different.

As shown in FIG. 16, in the second pixel PG22, similarly to the first pixel PG21, in a plan view facing the plane in which the relief layer 10R spreads, a plurality of island regions PG22a are sea islands having an aperiodic shape and arrangement. It has a structure. In the sea-island structure, a portion surrounding the plurality of island regions PG22a is a sea region PG22b. One of the sea region PG22b and the island region PG22a has a second uneven structure, and the other has a blank structure.

In this embodiment, each island region PG22a has a rectangular shape. While the plurality of island regions PG22a each have a rectangular shape, the width and length of each island region PG22a are aperiodic. In the plurality of island regions PG22a, both the x-direction dimension and the y-direction dimension may be aperiodic, or either the x-direction dimension or the y-direction dimension may be aperiodic. good. Note that at least one of the width and length of each island region PG22a preferably has randomness.

Furthermore, the plurality of island regions PG22a are arranged aperiodically within each pixel 10P in a plan view facing the plane in which the relief layer 10R extends. For example, the plurality of island regions PG22a may be arranged within one pixel 10P so that both the spacing in the x direction and the spacing in the y direction are aperiodic, or the spacing in the x direction and the spacing in the y direction are aperiodic. Either one of the intervals may be arranged to be non-periodic. Note that it is more preferable that the plurality of island regions PG22a are arranged within one pixel 10P so that at least one of the intervals in the x direction and the intervals in the y direction has randomness.

In this embodiment, in each pixel 10P included in the second pixel group PG2, the shape and arrangement of the plurality of island regions PG21a and PG22a are different from the shape and arrangement of the plurality of island regions PG21a and PG22a in other pixels 10P. Therefore, the shape and arrangement of the island region PG22a in the second pixel PG22 are different from the shape and arrangement of the island region PG21a in the first pixel PG21.

The second uneven structure of the sea-island structure will be described in more detail with reference to FIGS. 17 to 21. Note that the blank structure of the sea-island structure is the same as the blank structure of each pixel 10P included in the first pixel group PG1, except that the positions in the relief layer 10R are different from each other. Therefore, a detailed explanation of the blank structure of the pixel 10P of the second pixel group PG2 will be omitted.

FIG. 17 shows an example of the shape of the second uneven structure in a cross section perpendicular to the plane in which the relief layer 10R spreads. FIG. 21 shows the shapes of the second uneven structure and the first uneven structure in a cross section perpendicular to the plane in which the relief layer 10R spreads. In addition, in FIG. 17 and FIG. 21, for convenience of explanation and illustration, the angle of the incident light that enters each structure and the angle of the reflected light reflected by each structure are such that the intensity of each of the incident light and the reflected light is the highest. Only angles shown are shown.

As shown in FIG. 17, the second uneven structure UE2 of this embodiment has a wave shape that repeats periodically along one direction in a cross section perpendicular to the plane in which the relief layer 10R spreads. The period P2 of the second uneven structure UE2 is larger than the period P1 of the first uneven structure UE1. The period P2 of the second uneven structure UE2 is, for example, greater than 500 nm and less than or equal to 2000 nm. It is preferable that the height H2 of the second uneven structure UE2 is, for example, 100 nm or more and 200 nm or less. Note that the second uneven structure UE2 has a convex surface including the top and a concave surface including the bottom. The period P2 of the second uneven structure UE2 is the distance between two mutually adjacent tops in the second uneven structure UE2. The height H2 of the second uneven structure UE2 is the distance between the top and bottom of the second uneven structure UE2.

In this embodiment, the second uneven structure UE2 is a reflective first-order diffraction grating. The second uneven structure UE2 may be any one selected from a sinusoidal diffraction grating, a blazed diffraction grating, and a binary diffraction grating. The second uneven structure UE2 may include two or more of these diffraction gratings.

When the second uneven structure UE2 is a sinusoidal diffraction grating, the second The uneven structure UE2 has a sinusoidal shape. When the second uneven structure UE2 is a blazed diffraction grating, the second uneven structure is formed in a cross section perpendicular to the plane in which the relief layer 10R extends and also perpendicular to the direction in which the concave and convex surfaces included in the second uneven structure UE2 extend. The structure UE2 has a serration shape. When the second uneven structure UE2 is a binary diffraction grating, the second uneven structure is formed in a cross section that is perpendicular to the plane in which the relief layer 10R extends and perpendicular to the direction in which the concave and convex surfaces included in the second uneven structure UE2 extend. The structure UE2 has a shape that approximates a sawtooth. More specifically, in the second uneven structure UE2, the slope that reflects the incident light is approximated by a stepped surface.

Whichever diffraction grating the second concavo-convex structure UE2 is, it reflects diffracted light having a specific period that satisfies the following equation (10) at a specific diffraction angle. In the second uneven structure UE2, the diffracted light is the reflected light RL, and the diffraction angle is the second reflection angle θR2.

d(sinα+sinβ)=mλ...Equation (10)
In the above formula (10), d is the period of the diffraction grating, α is the incident angle, β is the diffraction angle, m is the diffraction order, and λ is the wavelength of light.

In the second uneven structure UE2, when the concave portions and convex portions included in the second uneven structure UE2 are repeated at a single period P2, the first-order diffracted light reflected by the second uneven structure UE2 is separated into spectra. As a result, when the second concavo-convex structure UE2 is observed by the observer OB, the observer OB can see that the second concave-convex structure UE2 is The second image PIC2 having rainbow colors to be displayed can be visually recognized.

On the other hand, the second uneven structure UE2 can reflect achromatic light by being designed as follows. First, the predetermined period d calculated using the above-mentioned equation (10) is set as the reference period dr. Next, a plurality of periods d are set discretely in a positive direction with respect to the reference period dr, that is, in a range larger than the reference period dr, and in a negative direction with respect to the reference period dr, that is, in a range smaller than the reference period dr. , a plurality of periods d are set discretely. A second uneven structure UE2 including an uneven surface corresponding to each of the plurality of periods d thus set is designed. According to the second uneven structure UE2, at a specific observation position, the wavelength of the first-order diffracted light reflected by the uneven surface having each period d is the uneven surface having a period d different from the period d of the uneven surface. is different from the wavelength of the first-order diffracted light that is reflected. As a result, at the observation position, light of a plurality of wavelengths is mixed, so when the second uneven structure UE2 is observed from the observation position, the second uneven structure UE2 displays an achromatic color, that is, formed by white light. The image is visually recognized by the observer OB.

Note that when designing the plurality of periods d described above, a period d that can reflect light of a wavelength with high relative luminous efficiency can be set as the reference period dr. The light having a wavelength with high relative luminous efficiency is, for example, green light having a wavelength within the range of 540 nm or more and 560 nm or less. In this case, the light reflected by the second concavo-convex structure UE2 includes green light having a high relative luminous efficiency and light having a relative luminous efficiency similar to the green light. Therefore, the image displayed by the second concavo-convex structure UE2 is easily visible to the observer OB. Moreover, the light reflected by the second concavo-convex structure UE2 can include red light having a longer wavelength and blue light having a shorter wavelength with respect to the green light. This makes it easy to make the light reflected by the second uneven structure UE2 achromatic light.

In the second uneven structure UE2, the uneven surface having the reference period dr has the highest density, and the uneven surface having a period d with a larger deviation from the reference period dr has a lower density in the second uneven structure UE2. It is preferable. Thereby, it is possible to reduce the intensity of the first-order diffracted light reflected at observation positions other than the above-mentioned specific observation position.

It is preferable that the second uneven structure UE2 capable of reflecting achromatic light satisfies the following formulas (11) to (13). However, in the following equation (11), r is 221 or less.

FIG. 18 shows a curve that satisfies the above equations (11) to (13).
As shown in FIG. 18, in the above equations (11) to (13), θ _R ′ is the range of the diffraction angle θ. θ' is the discrete interval, that is, the difference between the diffraction angle θ of the first-order diffracted light on a certain uneven surface and the diffraction angle θ of the first-order diffracted light on the uneven surface with the next largest period d or smallest period d of that uneven surface. It is. θ _n ′ is a discrete angle, that is, the difference between the diffraction angle θ of the first-order diffracted light on a certain uneven surface and the diffraction angle θ of the first-order diffracted light on the uneven surface having the reference period dr. ρ _n ′ is the density of all the uneven surfaces occupied by uneven surfaces having a specific discrete angle θ _{n ′} .

In the second uneven structure UE2 that satisfies equations (11) to (13), the first-order diffraction angle of the uneven surface is a discrete angle that is the diffraction angle θ on each uneven surface with respect to 0° corresponding to the reference period dr. θ _n ′ changes by discrete intervals θ′. In the second uneven structure UE2, the density of the uneven surface having the reference period dr has a maximum value, and the larger the discrete angle θ _n ' of the uneven surface becomes, the smaller the density of the uneven surface becomes.

In this way, the second uneven structure UE2 that satisfies Expressions (11) to (13) includes a plurality of values in the period d of the uneven surface. For example, the period d of the uneven surface includes a plurality of periods included in the range from 800 nm to 3200 nm. Therefore, compared to the case where the second uneven structure UE2 includes only one value in the period d of the uneven surface as shown in FIG. is difficult to counterfeit.

Note that the r value is a parameter that contributes to the range θ _R ′ of the diffraction angle θ. The r value is an important parameter for realizing that the light reflected by the second uneven structure UE2 is achromatic. The r value is preferably 221 or less.

FIG. 19 shows spectra of reflected light from nine displays having different r values. The spectrum shown in FIG. 19 is obtained using the display body 10 based on the uneven surface that undergoes first-order diffraction at 25 degrees when light with a wavelength of 540 nm is incident on the display body from 0 degrees, that is, from directly above. This is the obtained spectrum. Further, in each display body 10, the r value is set to one of 255, 238, 221, 204, 187, 170, 153, 136, and 119.

As shown in FIG. 19, the first spectrum S1 is obtained when the r value is set to 255, the second spectrum S2 is obtained when the r value is set to 238, and the second spectrum S2 is obtained when the r value is set to 221. , a third spectrum S3 is obtained. Also, when the r value is set to 204, the fourth spectrum S4 is obtained, when the r value is set to 187, the fifth spectrum S5 is obtained, and when the r value is set to 170, the sixth spectrum S6 is obtained. can get. Also, when the r value is set to 153, the seventh spectrum S7 is obtained, when the r value is set to 136, the eighth spectrum S8 is obtained, and when the r value is set to 119, the ninth spectrum S9 is obtained. can get. As is clear from the first spectrum S1 to the ninth spectrum S9, the smaller the r value, the wider the range of the acceptance angle of the light reflected from the display, in other words, the first-order diffraction angle. On the other hand, as is clear from the first spectrum S1 to the ninth spectrum S9, as the r value increases, the intensity of the light received at 25°, that is, the intensity of the first-order diffracted light reflected at 25° increases. .

FIG. 20 shows the positions of reflected light on the nine display bodies described above in the xy chromaticity diagram.
As shown in FIG. 20, the reflected light having the first spectrum S1 and the reflected light having the second spectrum S2 have green color. On the other hand, the reflected light having any of the third spectrum S3 to the ninth spectrum S9 has white color. Therefore, the r value in the above formula (11) is preferably 221 or less. Moreover, it is preferable that the r value is included in the range of 204 or more and 221 or less. Thereby, it is possible to suppress a decrease in the intensity of reflected light. Note that in FIG. 21, the area surrounded by the broken line is a white area including the white point WP (x=0.33, y=0.33).

The second uneven structure UE2 in this embodiment can display the achromatic second image PIC2 by satisfying the above formulas (11) to (13). Therefore, when the first image PIC1 is a chromatic image and the second image PIC2 is an achromatic image, when both the first image PIC1 and the second image PIC2 are chromatic images, and when the first image PIC2 is a chromatic image, Compared to the case where both the image PIC1 and the second image PIC2 are achromatic images, the visibility of the display body 10 can be increased.

As shown in FIG. 21, in the display body 10, the first reflection angle θR1 at which the first uneven structure UE1 reflects the incident light IL, and the second reflection angle θR2 at which the second uneven structure UE2 reflects the incident light IL. are different from each other. Therefore, the display body 10 can display the first image PIC1 formed by the first uneven structure UE1 while not displaying the second image PIC2 formed by the second uneven structure UE2, and display the second image PIC2 while displaying the first image PIC2 formed by the second uneven structure UE2. It is possible to have a state in which the first image PIC1 due to the uneven structure UE1 is not displayed.

In addition, in FIG. 21, the height H1 that the first uneven structure UE1 has is equal to the height H2 that the second uneven structure UE2 has. The height H1 of the first uneven structure UE1 may be higher or lower than the height H2 of the second uneven structure UE2.

[Third pixel group]
The third pixel group PG3 will be described with reference to FIGS. 22 to 29. Below, a first example and a second example of the pixel 10P included in the third pixel group PG3 will be described in order. Note that while the first example of the pixels 10P included in the third pixel group PG3 does not include the blank structure described above, the second example includes the blank structure.

As shown in FIG. 22, the third pixel group PG3 includes a plurality of pixels 10P. The plurality of pixels 10P are lined up without gaps. In this embodiment, each pixel 10P has a square shape. It is preferable that the pixel 10P included in the third pixel group PG3 has the same shape and size as the pixel 10P included in the first pixel group PG1 and the pixel 10P included in the second pixel group PG2. The third pixel group PG3 includes a first pixel PG31 and a second pixel PG32.

The pixel 10P included in the third pixel group PG3 may have a polygonal shape other than a square shape, similar to the pixel 10P included in the first pixel group PG1 and the pixel 10P included in the second pixel group PG2.

FIG. 23 shows an enlarged view of the first example of the first pixel PG31.
As shown in FIG. 23, the first pixel PG31 includes a plurality of sub-pixels PGS. The plurality of sub-pixels PGS are lined up without gaps. In this embodiment, each sub-pixel PGS has a square shape. Each sub-pixel PGS may have a polygonal shape other than a square. The plurality of sub-pixels PGS are composed of a plurality of first sub-pixels PGS1 and a plurality of second sub-pixels PGS2. Each first sub-pixel PGS1 includes a first uneven structure UE1. The first uneven structure UE1 is located over the entirety of each first sub-pixel PGS1. Each second sub-pixel PGS2 includes a second uneven structure UE2. The second concavo-convex structure UE2 is located throughout each second sub-pixel PGS2.

Within the first pixel PG31, the plurality of first sub-pixels PGS1 and the plurality of second sub-pixels PGS2 are each arranged aperiodically. Within the first pixel PG31, the plurality of first sub-pixels PGS1 and the plurality of second sub-pixels PGS2 may be arranged randomly.

FIG. 24 shows an enlarged view of the first example of the second pixel PG32.
As shown in FIG. 24, the second pixel PG32 includes a plurality of sub-pixels PGS, like the first pixel PG31. The plurality of sub-pixels PGS are lined up without gaps. The plurality of sub-pixels PGS are composed of a plurality of first sub-pixels PGS1 and a plurality of second sub-pixels PGS2. Each first sub-pixel PGS1 includes a first uneven structure UE1. The first uneven structure UE1 is located over the entirety of each first sub-pixel PGS1. Each second sub-pixel PGS2 includes a second uneven structure UE2. The second concavo-convex structure UE2 is located throughout each second sub-pixel PGS2.

Within the second pixel PG32, the plurality of first sub-pixels PGS1 and the plurality of second sub-pixels PGS2 are each arranged aperiodically. Within the second pixel PG32, the plurality of first sub-pixels PGS1 and the plurality of second sub-pixels PGS2 may be arranged randomly.

In the present embodiment, in each pixel 10P included in the third pixel group PG3, the arrangement of the first sub-pixel PGS1 and the arrangement of the second sub-pixel PGS2 are the same as the arrangement of the first sub-pixel PGS1 in the other pixel 10P, and , is different from the arrangement of the second sub-pixel PGS2. Note that within one pixel 10P, a plurality of first sub-pixels PGS1 and a plurality of second sub-pixels PGS2 are arranged aperiodically, while between different pixels 10P, a plurality of first sub-pixels PGS1 and a plurality of second sub-pixels PGS2 are arranged aperiodically. The arrangement of the pixel PGS1 and the plurality of second sub-pixels PGS2 may be the same.

FIG. 25 shows a second example of pixels 10P that can be included in the third pixel group PG3. FIG. 25 shows, for example, a planar structure of the first pixel PG31 included in the third pixel group PG3.
As shown in FIG. 25, like the pixel 10P included in the first pixel group PG1 and the pixel 10P included in the second pixel group PG2, the first pixel PG31, in a plan view facing the plane in which the relief layer 10R spreads, A plurality of island regions PG31a and PG31b have a sea-island structure with an aperiodic shape and arrangement. However, the first pixel PG31 included in the third pixel group PG3 is different from the first pixel group PG3 in that the plurality of island regions are composed of a plurality of first island regions PG31a and a plurality of second island regions PG31b. and the pixel 10P included in the second pixel group PG2.

Each of the first island region PG31a, the second island region PG31b, and the sea region PG31c has one of a first uneven structure UE1, a second uneven structure UE2, and a blank structure BL, and Different structures are located. In this embodiment, for example, the first uneven structure UE1 is located in the first island region PG31a, the second uneven structure UE2 is located in the second island region PG31b, and the blank structure BL is located in the sea region PG31c. There is.

Thereby, in the third pixel group PG3, both the first uneven structure UE1 and the second uneven structure UE2 are arranged irregularly. Therefore, in the part displayed by the third pixel group PG3 in the first image PIC1 and in the part displayed by the third pixel group PG3 in the second image PIC2, the periodicity of the arrangement of the island area The resulting diffracted light, in other words, noise can be suppressed. Therefore, the visibility of the first image PIC1 and the second image PIC2 is improved.

In this embodiment, each first island region PG31a and each second island region PG31b have a rectangular shape or a combination of a plurality of rectangular shapes. In the plurality of first island regions PG31a, the width and length of each first island region PG31a are aperiodic. Moreover, in the plurality of second island regions PG31b, the width and length of each second island region PG31b are aperiodic. Furthermore, in the entire island region including the plurality of first island regions PG31a and the plurality of second island regions PG31b, the width and length of each island region are aperiodic.

In the plurality of first island regions PG31a, both the x-direction dimension and the y-direction dimension may be aperiodic, or either the x-direction dimension or the y-direction dimension may be aperiodic. It's okay. In the plurality of second island regions PG31b, both the dimension in the x direction and the dimension in the y direction may be non-periodic, or the dimension in the x direction and the dimension in the y direction may be non-periodic. It's okay. In the entire island region, both the x-direction dimension and the y-direction dimension may be aperiodic, or either the x-direction dimension or the y-direction dimension may be aperiodic.

Further, the plurality of first island regions PG31a are arranged aperiodically within each pixel 10P in a plan view facing the plane in which the relief layer 10R extends. For example, the plurality of first island regions PG31a may be arranged within one pixel 10P so that both the spacing in the x direction and the spacing in the y direction are aperiodic, or the spacing in the x direction and the spacing in the y direction are aperiodic. The spacing in either direction may be arranged to be non-periodic.

The plurality of second island regions PG31b are arranged aperiodically within each pixel 10P in a plan view facing the plane in which the relief layer 10R extends. For example, the plurality of second island regions PG31b may be arranged within one pixel 10P so that both the interval in the x direction and the interval in the y direction are aperiodic, or the interval in the x direction and the interval in the y direction are aperiodic. The spacing in either direction may be arranged to be non-periodic.

The entire island region is arranged aperiodically within each pixel 10P in a plan view facing the plane in which the relief layer 10R extends. For example, the plurality of island regions may be arranged within one pixel 10P so that both the intervals in the x direction and the intervals in the y direction are aperiodic, or the intervals in the x direction and the intervals in the y direction may be arranged so that either one is aperiodic. The distance between adjacent island regions is preferably 100 μm or less in both the x direction and the y direction. Further, when analyzing the display body 10 using a verifier, the distance between adjacent island regions needs to be larger than the resolution limit of the verifier. The verifier is, for example, a microscope and a camera.

Note that the pixel 10P included in the third pixel group PG3 includes the above-described sub-pixel PGS, and may also include the blank structure BL.
That is, as shown in FIG. 26, the first pixel PG31, which is one of the pixels 10P included in the third pixel group PG3, includes a plurality of sub-pixels PGS. The plurality of sub-pixels PGS are lined up without gaps. Either one of the first uneven structure UE1 and the second uneven structure UE2 is located in each sub-pixel PGS. However, each of the first uneven structure UE1 and the second uneven structure UE2 is located only in a part of the sub-pixel PGS where the uneven structure is located. In each sub-pixel PGS, a blank structure BL is located in a portion where no uneven structure is located. In the example shown in FIG. 26, the first uneven structure UE1 and the second uneven structure UE2 are arranged alternately in the x direction and the y direction, but the first uneven structure UE1 and the second uneven structure UE2 are different from each other. May be arranged periodically.

In this embodiment, in a plan view facing the plane on which the relief layer 10R spreads, the sub-pixel PGS has a square shape, and the outer shape of the first uneven structure UE1 and the outer shape of the second uneven structure UE2 are square. It has a shape. Therefore, the dimension in the x direction, the dimension in the y direction in the outer shape of the uneven structure, the difference Δx between the center PC of the sub-pixel PGS in the x direction and the center UC of the uneven structure, and the center PC of the sub pixel PGS and the unevenness in the y direction. It is possible to specify the position of the concavo-convex structure within each sub-pixel PGS based on the difference Δy from the center UC of the structure.

In addition, in this example as well, the dimension in the x direction and the dimension in the y direction of the outer shape of the uneven structure, the difference Δx between the center PC of the subpixel PGS in the x direction and the center UC of the uneven structure, and the subpixel PGS in the y direction. By adjusting the difference Δy between the center PC and the center UC of the uneven structure, it is possible to arrange a plurality of uneven structures non-periodically.

[Authenticity determination method]
A method for determining the authenticity of the display body 10 will be described with reference to FIGS. 27 to 31. Below, as an example of the method for determining authenticity using a verifier, a method for determining authenticity using the third pixel group PG3 included in the display body 10 will be described. However, the method described below is not limited to the third pixel group PG3 included in the display body 10, but can also be performed using either the first pixel group PG1 or the second pixel group PG2. Moreover, two or more of the first pixel group PG1, the second pixel group PG2, and the third pixel group PG3 may be used in the authentication method.

Note that in FIGS. 27 and 28 referred to below, the first pixel PG31 described earlier with reference to FIG. 25 is shown as an example of a region used for determining the authenticity of the display body 10. However, in determining the authenticity of the display 10, the authenticity of the display 10 may be determined using one pixel 10P included in the display 10, or an area including a plurality of pixels 10P provided in the display 10 may be determined. It may also be the subject of

As shown in FIG. 27, the display body 10 is in a state where the second island region PG31b and the sea region PG31c are distinguished by mutual contrast, while there is almost no contrast between the first island region PG31a and the sea region PG31c. It is possible to have When the incident light IL that enters the display body 10 has a specific incident angle and the observation angle by the verifier is a specific observation angle, the display body 10 can have this state. In this case, the image formed by the contrast difference between the second island region PG31b and the region including the first island region PG31a and the sea region PG31c functions as a determination image for determining the authenticity of the display body 10. Is possible. That is, the third pixel group PG3 records the shape of the second island region PG31b and the position of the second island region PG31b within the first pixel PG31 as a machine-readable code.

As shown in FIG. 28, in the display body 10, the first island region PG31a and the sea region PG31c are distinguished by mutual contrast, and the second island region PG31b and the sea region PG31c are distinguished by mutual contrast. On the other hand, it is possible to have a state in which almost no contrast occurs between the first island region PG31a and the second island region PG31b. When the incident light IL that enters the display body 10 has a specific incident angle and the observation angle by the verifier is a specific observation angle, the display body 10 can have this state. Note that at least one of the incident angle and the viewing angle when the display body 10 has the state shown in FIG. 28 is different from the conditions when the display body 10 has the state shown in FIG. 27.

In this case, the image formed by the contrast difference between the first island region PG31a, the second island region PG31b, and the sea region PG31c can function as a determination image for determining the authenticity of the display body 10. be. That is, the third pixel group PG3 records the shapes of the island regions PG31a and PG31b and the positions of the island regions PG31a and PG31b within the first pixel PG31 as machine-readable codes.

As shown in FIG. 29, the second island region PG31b may have the shape of specific characters, symbols, numbers, and the like. In the example shown in FIG. 29, the first pixel PG31 has four second island regions PG31b, and any one of the four second island regions PG31b is "T", "P", "1", and It has a shape corresponding to any one of "9". That is, the third pixel group PG3 records the shape of the second island region PG31b 31b and the position of the second island region PG31b within the first pixel PG31 as a machine-readable code.

Note that, as described above, each island region PG31a, PG31b included in the display body 10 is very minute, so if the observer OB simply observes the display body 10 with the naked eye without using a verification device, the display body 10, the structure used for authentication cannot be visually recognized.

An example of the procedure in the method for determining the authenticity of the display body 10 will be described with reference to FIGS. 30 and 31.
As shown in FIG. 30, in determining the authenticity of the display 10, the position of the light source LS with respect to the display 10 is adjusted so that the incident light enters the display 10 at a specific incident angle α. Further, the position of the verifier VF with respect to the display body 10 is adjusted so that the reflected light reflected from the display body 10 at a specific reflection angle β can be received. Thereby, the image displayed by the display body 10 is captured by the verifier VF.

As shown in FIG. 31, in determining the authenticity of the display body 10, first, an image displayed by the display body 10 is captured using the verifier VF (step S11). Thereby, a determination image used for determining the authenticity of the display body 10 can be obtained. Next, the determination image captured by the verifier VF is compared with a reference image for determination prepared in advance (step S12). The comparison between the determination image captured by the verifier VF and the reference image may be performed using the verifier VF. Alternatively, the determination image captured by the verifier VF may be transmitted to a computer connected to the verifier VF, and the transmitted determination image and the reference image stored in the computer may be compared by the computer. Alternatively, the judgment image taken by the verifier VF is sent to a computer connected to the verifier VF, and further, the judgment image taken by the verifier VF is sent to a server connected to the computer, and the judgment image is stored in the server. The reference image sent to the server may be compared with the determination image sent to the server.

Next, the authenticity of the display body 10 is determined based on the result of comparing the two images (step S13). In the comparison for determining the authenticity of the display body 10, it is possible to use at least one of a pattern included in the image, a luminance distribution in the image, and a color distribution in the image. Note that such a determination can be made by the medium on which the two images are compared.

Then, the result of the authenticity determination of the display body 10 is output (step S14). When the processes of step S12 and step S13 are performed by the verifier VF, the verifier VF can also output the result of the authenticity determination. Furthermore, when the processing in steps S12 and S13 is performed by a computer, the computer can also output the results of the authenticity determination. When the processes of step S12 and step S13 are performed by a server, for example, the server may transmit the results of the authentication determination to the computer, and the computer may output the results of the authentication determination based on the transmitted data. It is. The result of the authenticity determination is output to, for example, a display unit included in the verifier VF or the computer.

As explained above, according to one embodiment of the display, the effects described below can be obtained.
(1) Since the pixel 10P of the first pixel group PG1 has a sea-island structure in which the island regions PG11a and PG12a are arranged aperiodically, noise based on the periodicity in the arrangement of the first pixel group PG1 is suppressed, and as a result, the The visibility of one image PIC1 is improved. Furthermore, since it is possible to determine the authenticity of the display body 10 using the code recorded by the third pixel group PG3, it is possible to increase the resistance of the display body 10 against forgery.

(2) In each pixel 10P included in the first pixel group PG1, when the shape and arrangement of the plurality of island regions PG11a and PG12a are different from the shape and arrangement of the plurality of island regions PG11a and PG12a in other pixels 10P, , noise based on periodicity in the arrangement is more reliably suppressed, and the visibility of the first image PIC1 is more reliably improved.

(3) The first uneven structure UE1 has a sub-wavelength structure because the area over which the incident light that has entered the first uneven structure UE1 propagates while undergoing multiple reflections is guaranteed by the area of the island regions PG11a and PG12a. In some cases, the coloring intensity of reflected light due to waveguide mode resonance can be increased.

(4) In the first pixel group PG1, even if the optical effect of the light reflected by the island regions PG11a and PG12a is weakened by the light reflected by the blank structure BL, the area ratio of the first uneven structure UE1 can be increased. As a result, unevenness in shading in the first image PIC1 is suppressed.

(5) Since the light reflected by the blank structure BL does not affect the light reflected by the first concavo-convex structure UE1, unevenness in density in the first image PIC1 caused by the light reflected by the blank structure BL is suppressed.

(6) Since the pixel 10P of the second pixel group PG2 has a sea-island structure in which the island regions PG21a and PG22a are arranged aperiodically, noise based on the periodicity in the arrangement of the second pixel group PG2 is suppressed, and as a result, the The visibility of the two images PIC2 is improved.

(7) Since both the first uneven structure UE1 and the second uneven structure UE2 are arranged irregularly in the third pixel group PG3, the portion of the first image PIC1 that is displayed by the third pixel group PG3 , and the visibility of the portion of the second image PIC2 displayed by the third pixel group PG3 is improved.

Note that the embodiment described above can be modified and implemented as follows.
[First pixel group]
- Even if the blank structure BL reflects light in the regular reflection direction, the ratio of the total area of the first uneven structure UE1 included in the third pixel group PG3 to the total area of the third pixel group PG3, and the first The ratio of the total area of the first uneven structure UE1 included in the first pixel group PG1 to the total area of the pixel group PG1 may be equal. Even in this case, since the pixels 10P included in the first pixel group PG1 have a sea-island structure, it is possible to obtain an effect similar to (1) described above.

- In the sea-island structure, the first uneven structure UE1 may be included in the sea area, and the blank structure BL may be included in the island area. Even in this case, since the pixels 10P included in the first pixel group PG1 have a sea-island structure, it is possible to obtain an effect similar to (1) described above.

- The first uneven structure UE1 included in the first pixel group PG1 may be a first-order diffraction grating that reflects the first-order diffracted light. Even in this case, since the first reflection angle θR1 in the first uneven structure UE1 is different from the second reflection angle θR2 in the second uneven structure UE2, the display body 10 can display only the first image PIC1. It is possible to have a state where only the second image PIC2 is displayed and a state where only the second image PIC2 is displayed.

- In each pixel 10P included in the first pixel group PG1, the shape and arrangement of the plurality of island regions may be the same as the shape and arrangement of the plurality of island regions in other pixels 10P. In this case, the effects described below can be obtained.

(8) Manufacturing of the display body 10 can be facilitated by facilitating the design of the first pixel group PG1 while suppressing noise based on periodicity in the arrangement of each pixel 10P belonging to the first pixel group PG1. can.

- In each pixel PG11, PG12, in the sea-island structure, the plurality of island regions PG11a, PG12a can have at least one of an aperiodic shape and an aperiodic arrangement. In other words, even if the plurality of island regions PG11a and PG12a have only an aperiodic shape or an aperiodic arrangement, the effect according to (1) is achieved according to such aperiodicity. It is possible to obtain.

[Second pixel group]
- In the sea-island structure, the second uneven structure UE2 may be included in the sea area, and the blank structure BL may be included in the island area. Even in this case, the effect similar to (6) described above can be obtained because the pixels 10P included in the first pixel group PG1 have a sea-island structure.

- In each pixel PG21, PG22, in the sea-island structure, the plurality of island regions PG21a, PG22a can have at least one of an aperiodic shape and an aperiodic arrangement. In other words, even if the plurality of island regions PG11a and PG22a have only an aperiodic shape or an aperiodic arrangement, the effect according to (6) is achieved according to such aperiodicity. It is possible to obtain.

- The pixels 10P included in the second pixel group PG2 do not need to have a sea-island structure. In the second pixel group PG2, the pixels including the second uneven structure UE2 and the pixels including the blank structure BL may be arranged in a checkerboard pattern or in a stripe pattern. Even in this case, the above-mentioned effect (1) can be obtained at least for the first pixel group PG1.

- In each pixel 10P included in the second pixel group PG2, the shape and arrangement of the plurality of island regions may be the same as the shape and arrangement of the plurality of island regions in other pixels 10P. In this case, manufacturing of the display body 10 is facilitated by facilitating the design of the second pixel group PG2 while suppressing noise based on periodicity in the arrangement of each pixel 10P belonging to the second pixel group PG2. be able to.

[Third pixel group]
- In the sea-island structure of each pixel 10P of the third pixel group PG3, the plurality of island regions PG31a and PG31b can have at least one of an aperiodic shape and an aperiodic arrangement. That is, the plurality of island regions PG31a and PG31b may have only an aperiodic shape or an aperiodic arrangement.

- A machine-readable code may be recorded in the third pixel group PG3, as will be described with reference to FIGS. 32 to 42. The machine-readable code is a code associated with the shape and arrangement of the region included in the third pixel group PG3.

FIG. 32 shows a part of the plurality of pixels 10P included in the third pixel group PG3.
In the example shown in FIG. 32, each pixel 10P included in the third pixel group PG3 has an island region 10P1 and a sea region 10P2. Note that in this example, each island region 10P1 is arranged discretely in the entire third pixel group PG3. On the other hand, the sea region 10P2 surrounds the plurality of island regions 10P1 in the entire third pixel group PG3. The island area 10P1 has a first uneven structure UE1, and the sea area 10P2 has a second uneven structure UE2. Note that the island area 10P1 may have the second uneven structure UE2, and the sea area 10P2 may have the first uneven structure UE1.

The island region 10P1 has a shape similar to that of the pixel 10P. In this example, the pixel 10P has a square shape, and the island region 10P1 also has a square shape. The sea area 10P2 is located in a part other than the part where the island area 10P1 is located in the pixel 10P to which the sea area 10P2 belongs. The area of the island region 10P1 may be equal to or different from the area of the sea region 10P2. In each pixel 10P, from the viewpoint of making it difficult to create a difference between the intensity of light reflected by the island region 10P1 and the intensity of light reflected by the sea region 10P2, the area of the island region 10P1 is the same as the area of the sea region 10P2. Preferably equal. On the other hand, if it is desired to emphasize the optical effect in either the island region 10P1 or the sea region 10P2, the area ratio of each may be adjusted.

The center of each island region 10P1 is located shifted both in the vertical direction and in the horizontal direction with respect to the center of the pixel 10P to which the island region 10P1 belongs. One vertex of the island region 10P1 is located at one of the vertices of the pixel 10P to which the island region 10P1 belongs.

Each pixel 10P may have a blank structure 10P3. The blank structure 10P3 is located between the island region 10P1 and the sea region 10P2. In the example shown in FIG. 32, the blank structure 10P3 has an L-shape. The blank structure 10P3 has a shape along the sides of the island region 10P1 other than the side that is in contact with the side of the pixel 10P.

FIG. 33 is a table showing the arrangement of regions in the pixel 10P included in the third pixel group PG3 and an example of the code associated with the arrangement.
As shown in FIG. 33, for the area included in the pixel 10P, for example, it is possible to associate codes with the following three elements. In the following, for convenience of explanation, the horizontal direction and the vertical direction in the plane of the paper in which FIG. 33 is shown are used.

(Element 1) Position of the island region 10P1 in the left-right direction (Element 2) Position of the island region 10P1 in the vertical direction (Element 3) Presence or absence of blank structure 10P3

In element 1, when the center of island region 10P1 is shifted to the left with respect to the center of pixel 10P, it is possible to associate code "0". Further, when the center of the island region 10P1 is shifted to the right with respect to the center of the pixel 10P, it is possible to associate the code "1". In element 2, if the center of the island region 10P1 is shifted upward with respect to the center of the pixel 10P, it is possible to associate the code "0". Further, when the center of the island region 10P1 is shifted downward from the center of the pixel 10P, it is possible to associate the code "1". In element 3, when the pixel 10P has a blank structure 10P3, it is possible to associate the code "0". Further, when the pixel 10P does not have the blank structure 10P3, it is possible to associate the code "1" with the pixel 10P.

FIG. 34 shows a part of the pixels 10P included in the third pixel group PG3 shown in FIG. 32. Specifically, four pixels 10P located at the bottom of the third pixel group PG3 shown in FIG. 32 are shown.

As shown in FIG. 34, codes "011", "111", "010", and "111" are recorded in the four pixels 10P in order from the left side of the page. Thereby, it is possible to record a 3-bit code with one pixel 10P. Therefore, for example, when the four pixels 10P are the unit of reading in the code recorded in the third pixel group PG3, the sequence of "011111010111" is read as the code. That is, a 12-bit code is recorded by four pixels 10P. Note that the reading range in the third pixel group PG3 is composed of a plurality of reading units. When determining the authenticity of the display body 10 based on the code read from the third pixel group PG3, the above-mentioned number sequence itself may be set as an authentication code for determining authenticity, or A digital code associated in advance may be set as an authentication code for determining authenticity.

As shown in FIG. 35, in each pixel 10P, the position of the island region 10P1 having a shape similar to that of the pixel 10P is between the center P1C of the island region 10P1 and the center 10PC of the pixel 10P to which the island region 10P1 belongs. It can be set by shifting in at least one of the left-right direction and the up-down direction. Therefore, it is easy to design the plurality of island regions 10P1 to be arranged irregularly in the entire third pixel group PG3.

In the code reading range set in the third pixel group PG3, the smaller the number of reading units in which the same code is recorded, the lower the possibility that the arrangement of the island regions 10P1 has periodicity. In a plurality of reading units, the ratio of reading units in which the same code is recorded is preferably less than 50%, more preferably less than 20%. Note that from the viewpoint of irregularly arranging the plurality of island areas 10P1, it is most preferable that the code recorded in each reading unit is different from that in other reading units.

Note that, as shown in FIG. 35, the third pixel group PG3 may have an island region 10P1 in which the center P1C of the island region 10P1 coincides with the center 10PC of the pixel 10P to which the island region 10P1 belongs. Alternatively, the third pixel group PG3 may have an island region 10P1 in which the center P1C of the island region 10P1 is shifted only in the vertical direction with respect to the center 10PC of the pixel 10P to which the island region 10P1 belongs. Alternatively, the third pixel group PG3 may have an island region 10P1 in which the center P1C of the island region 10P1 is shifted only in the left-right direction with respect to the center 10PC of the pixel 10P to which the island region 10P1 belongs.

In this way, by increasing the types of codes at the positions of the island areas 10P1 with respect to the pixels 10P, it is possible to increase the number of codes that each pixel 10P can record. Thereby, the possibility that the arrangement of the island regions 10P1 has periodicity can be lowered, and the resistance against counterfeiting in the display body 10 can also be increased.

Further, the blank structure 10P3 may have a shape that surrounds the entire outer edge of the island region 10P1. In the example shown in FIG. 32, the blank structure 10P3 may have a square frame shape. In this way, by increasing the types of shapes that the blank structure 10P3 can have, it is possible to increase the number of codes that each pixel 10P can record. Thereby, the display body 10 can be made more resistant to counterfeiting.

FIG. 36 shows an example of a change in the shape that the island area 10P1 can have in order to record a code in the island area 10P1.
As shown in FIG. 36, the island region 10P1 can have a protrusion P1a that protrudes into the pixel 10P from a region having a similar shape to the pixel 10P. The island region 10P1 can have a protrusion P1a at any position on the outer edge that partitions a region having a similar shape to the pixel 10P, in a portion that is not in contact with the pixel 10P. A code can be recorded in each pixel 10P depending on the position of the protrusion P1a in the island region 10P1. For example, the following eight types of codes can be set by the protrusion P1a based on a region where the protrusion P1a has a similar shape to the pixel 10P. That is, when the protrusion P1a is located on the left side of the upper side in a shape similar to the pixel 10P, or on the right side of the upper side, on the left side of the lower side, or on the right side of the lower side, and , which are located above the right side, can be linked to one code. In addition, when the protruding portion P1a is located below the right side of a shape similar to the pixel 10P, when it is located above the left side, or when it is located below the left side, each is tied to one code. It is possible to attach it.

Furthermore, the island region 10P1 does not have to have a similar shape to the pixel 10P. For example, although not shown in the drawing, if the island region 10P1 is a rectangle, each pixel 10P is coded based on which side of the island region 10P1 is longer, the vertically extending side or the horizontally extending side. It is also possible to record.

As described above, the third pixel group PG3 is capable of recording one authentication code using the plurality of pixels 10P. FIG. 37 shows an example in which the third pixel group PG3 records one authentication code using three pixels 10P. Note that since the third pixel group PG3 can record the authentication code using two or more pixels 10P, the number of pixels 10P that record one authentication code is not limited to three.

As shown in FIG. 37, it is possible to associate the alphabet "A" as an authentication code with a group of three consecutive pixels in which the island region 10P1 is located at the upper left of the pixel 10P. In the example described above using FIG. 33, the code "001" is recorded in the pixel where the island area 10P1 is located at the upper left of the pixel 10P. Further, it is possible to associate the alphabet "B" as an authentication code with a pixel group of three consecutive pixels in which the island region 10P1 is located at the upper right of the pixel 10P. Note that in the example described above with reference to FIG. 33, the code "101" is recorded in the pixel where the island area 10P1 is located at the upper right of the pixel 10P. Further, it is possible to associate the alphabet "C" as an authentication code with a pixel group of three consecutive pixels in which the island region 10P1 is located at the lower right of the pixel 10P. In the example described above with reference to FIG. 33, the code "111" is recorded in the pixel where the island area 10P1 is located at the lower right of the pixel 10P. Further, the authentication code recorded by the plurality of pixels 10P is not limited to alphabets, and may be, for example, numbers, kanji, kana, symbols, etc.

38 and 39 show a configuration including the authentication code illustrated in FIG. 37 and pixels for specifying whether or not the authentication code recorded by three pixel groups is to be subjected to authentication. There is.

As shown in FIG. 38, the third pixel group PG3 determines whether reading is necessary between three pixel groups that record one authentication code and three pixel groups that record another authentication code. The determination pixel 10PR to be determined is located. Note that in this example, a group of three pixels 10P lined up along the left-right direction of the page and a determination pixel 10PR located on the right side of the pixel group constitute one reading unit.

The determining pixel 10PR is a pixel that does not have both the island region 10P1 and the sea region 10P2. The determining pixel 10PR may be, for example, a pixel on which a predetermined shape is printed, or a pixel on which the shape is not printed. The predetermined shape may be, for example, letters, numbers, symbols, and figures. The method of printing the predetermined shape may be a laser marking method, an inkjet method, or the like. In the determining pixel 10PR, the pixel on which a predetermined shape is printed is the reading pixel PR2. When the reading unit includes the reading pixel PR2, the code included in the reading unit is used to determine the authenticity of the display body 10. On the other hand, in the determining pixel 10PR, a pixel on which a predetermined shape is not printed is a non-reading pixel PR1. When the reading unit includes the non-reading pixel PR1, the code included in the reading unit is not used to determine the authenticity of the display 10.

Note that the determination pixel 10PR may be a pixel in which a metal reflective layer is formed. In the determining pixel 10PR, the pixel on which the reflective layer is formed is the reading pixel PR2. On the other hand, in the determining pixel 10PR, a pixel on which a reflective layer is not formed is a non-reading pixel PR1. In this case, after forming a reflective layer on the entire surface of the third pixel group PG3, the part of the reflective layer formed in the determination pixel 10PR corresponding to the non-reading pixel PR1 is removed. It is possible to form pixel PR1. A method for removing a portion of the reflective layer may be, for example, laser ablation.

In the example shown in FIG. 38, the reading unit including the pixel group associated with the authentication code "A" includes the non-reading pixel PR1. Therefore, the authentication code "A" is not used to determine the authenticity of the display body 10. On the other hand, the reading unit including the pixel group associated with the authentication code "B" and the reading unit including the pixel group associated with "C" each include the reading pixel PR2. Therefore, the authentication codes "B" and "C" are used to determine the authenticity of the display body 10.

In the example shown in FIG. 39, a reading unit including a pixel group associated with the authentication code "A" and a reading unit including a pixel group associated with "C" each include the reading pixel PR2. . Therefore, the authentication codes "A" and "C" are used to determine the authenticity of the display body 10. On the other hand, the reading unit including the pixel group associated with the authentication code "B" includes the non-reading pixel PR1. Therefore, the authentication code "B" is not used to determine the authenticity of the display body 10.

Since the reading unit includes the determination pixel 10PR, as shown in FIGS. 38 and 39, even if the pixel group in which the authentication code is recorded is the same, the determination pixel 10PR is divided into the reading pixel PR2 and the non-reading pixel PR1. It is possible to change the authentication code used to determine the authenticity of the display body 10 depending on which of the following. Whether the determining pixel 10PR is the reading pixel PR2 or the non-reading pixel PR1 can be changed on demand.

According to the display body 10 having the determination pixel 10PR, in order to forge the display body 10, it is necessary to forge the uneven structure of the display body 10 and at the same time to forge the determination pixel 10PR. Therefore, the resistance of the display 10 against forgery is increased compared to the case where the display 10 does not include the determination pixel 10PR.

The third pixel group PG3 can include designation pixels for designating the reading range. 40 and 41 show examples of designation pixels that the third pixel group PG3 can include.

In the example shown in FIG. 40, the designation pixel 10PS is larger than the pixel 10P. The designation pixel 10PS can have the same size as the size occupied by the plurality of pixels 10P. For example, in the example shown in FIG. 40, the designation pixel 10PS has a size occupied by four pixels 10P. The designation pixel 10PS can include at least one of the first uneven structure UE1, the second uneven structure UE2, and the blank structure BL. In the third pixel group PG3, an area separated from other areas by the four designation pixels 10PS is a reading range that is a target for mechanical reading.

In the example shown in FIG. 41, the designation pixel 10PS has the same shape and size as the pixel 10P. The designation pixel 10PS, like the pixel 10P, includes an area having the first uneven structure UE1 and an area having the second uneven structure UE2. However, in the specification pixel 10PS, the position of the area having the first uneven structure UE1 in the specification pixel 10PS is different from the position of the island area 10P1 in the pixel 10P, and the second The position of the area having the uneven structure UE2 is different from the position of the sea area 10P2 within the pixel 10P. In the third pixel group PG3, an area separated from other areas by the four designation pixels 10PS is a reading range that is a target for mechanical reading.

Note that the third pixel group PG3 may include both the designation pixel 10PS shown in FIG. 40 and the designation pixel 10PS shown in FIG. 41. Further, the third pixel group PG3 may have a plurality of reading ranges separated by the designation pixels 10PS.

FIG. 42 shows an example of a procedure in a method for determining the authenticity of the display body 10 using the code recorded in the third pixel group PG3.
As shown in FIG. 42, when determining the authenticity of the display body 10, first, an image of the reading range included in the third pixel group PG3 is captured using the above-mentioned verifier. At this time, the island area 10P1, the sea area 10P2, and the blank structure within the pixel 10P are created by making light incident on the display body 10 from a predetermined first angle and capturing an image at a specific second angle. 10P3 can be acquired as an image with any contrast. For example, in FIG. 32 referred to above, the island region 10P1, the sea region 10P2, and the blank structure 10P3 are marked with dots having different densities. 10P3 is clearly divided. However, in reality, in the image taken of the display body 10, each region 10P1, 10P2 and the blank structure 10P3 are displayed using different optical characteristics such as brightness or color. The difference in characteristic value in optical specification, that is, the contrast, which each region 10P1, 10P2 and blank structure 10P3 have, changes depending on the incident angle, imaging angle, etc. described above. Note that the light source for the light that enters the display body 10 may be built into the verifier, or the light source and the verifier may be separated as long as the angle at which the light is incident and the angle at which the image is taken are fixed. good.

Next, the verifier inputs the image captured by the verifier to an input destination, which is either a server or a computer to which the verifier is connected (step S21). Then, the image input destination captures the image output by the verifier (step S22). Next, the image input destination performs predetermined preprocessing on the image in order to determine the authenticity of the display body 10 using the image (step S23).

Preprocessing is a process of processing captured images so that they can be easily authenticated. Taking the above-mentioned FIG. 32 as an example, if the optical characteristic value, for example, the contrast due to brightness, is small in each region of the captured image, it is necessary to clearly distinguish each region in the subsequent step of feature extraction. It is desirable to display an image. Therefore, as preprocessing, for example, a threshold value for brightness is set, and 50 in the 256 gradations of black and white is applied to areas with brightness lower than the threshold value, while areas with brightness higher than the threshold value are applied. It is possible to apply 150 of the 256 gradations to the area. In this way, in one example of preprocessing, a fixed gradation is assigned to each region, and thereby an image can be reconstructed.

Further, taking FIG. 27 as an example, when light is incident on the first island region PG31a, the second island region PG31b, and the sea region PG31c from a specific first angle, only the second island region PG31b is incident at a specific second angle. The first island region PG31a and the sea region PG31c may reflect at different angles, or vice versa. At this time, in FIG. 27, contrast is provided between the first island region PG31a and the second island region PG31b, but in reality, although the intensity is not as high as that of the second island region PG31b, There is also a possibility that the reflected light from the first island region PG31a is reflected at the second angle. Therefore, in the preprocessing, for example, by binarizing the image in terms of brightness, it is possible to bring the image used for authentication closer to the state shown in FIG. 27, thereby increasing the authentication accuracy.

Furthermore, as in the example shown in FIG. 28, if you want to integrate the first island region PG31a and the second island region PG31b and authenticate them as an image distinct from the sea region PG31c, the threshold for binarization is By adjusting the values, processing similar to the example shown in FIG. 27 becomes possible.

Note that the binarization of an image may be performed based on arbitrary color values such as brightness, saturation, and hue of the image, in addition to the brightness of the image. Further, the pre-processing may be a process of extracting only specific light from among the light incident on the verifier as light for use in authentication by using a polarizing filter.

Then, the image input destination extracts the features of the preprocessed image (step S24). As a result, the code recorded by the arrangement of the area in the pixel 10P included in the image is read. As described above, the image input destination reads a code consisting of at least one of "0" and "1" based on the arrangement of the area in the pixel 10P. In addition, if the code recorded according to the arrangement of the area in the pixel 10P is associated with another authentication code, the image input destination is the code read based on the arrangement of the area in the pixel 10P. It is converted into a digital code (step S25). On the other hand, if the code recorded according to the arrangement of the area at pixel 10P is not associated with another code, the image input destination uses the code recorded according to the arrangement of the area at pixel 10P as the authentication code. Treated as such. The image input destination then checks the authentication code against a pre-recorded determination code (step S26). Finally, the image input destination determines whether the display body 10 is a genuine display body based on the result of the verification (step S27). The image input destination determines that the display body 10 is an authentic display body when the authentication code matches the determination code. On the other hand, if the authentication code does not match the determination code, the image input destination determines that the display body 10 is a forged display body.

As explained above, when determining the authenticity of a code recorded by the arrangement of the area of the pixel 10P by machine reading, light is incident from a specific angle known only to the person making the determination, and the reflected light is also identified. The optical characteristic values of the image obtained when light is received at the angle are an important factor in determining authenticity. In other words, the pixel 10P must exhibit predetermined optical characteristics when light is incident from a specific angle. Therefore, the counterfeiter not only needs to copy only the appearance of the shape of the island area and the sea area, but also needs to create the uneven structure provided in each area with the same design and accuracy as the genuine pixel 10P. Therefore, it is difficult to counterfeit the display body 10. Furthermore, by recording a code in the third pixel group PG3, when the display body 10 is forged, the first island has different optical properties such as the angle and intensity of reflected light when light is incident on the display body 10. It becomes necessary to accurately imitate the uneven structure in both the region PG31a and the second island region PG31b. Therefore, for example, the effect of preventing counterfeiting of the display body 10 is even greater than when the island region has only one type of uneven structure, such as the first pixel group PG1 or the second pixel group PG2 described above. It gets expensive.

According to the modification described above, it is possible to obtain the effects described below.
(9) Since the third pixel group PG3 records a machine-readable code, it is possible to determine the authenticity of the display body 10 using the code. Thereby, it is possible to determine the authenticity of the display body 10 using both the images PIC1 and PIC2 that the display body 10 can display and the code recorded by the display body 10. Therefore, compared to the case where the display body 10 does not record a code, it is possible to increase the resistance of the display body 10 against counterfeiting.

- In the modification example of the third pixel group PG3 described above, the third pixel group PG3 can include a plurality of reading units in which the same code is recorded. Thereby, it is possible to increase the redundancy of the code recorded in the third pixel group PG3. Furthermore, in this case, it is also possible to correct errors occurring in any of the reading units by using reading units in which the same code is recorded.

- In the modification of the third pixel group PG3 described above, the authentication code recorded in each reading unit may include a parity bit that is an error detection code. Thereby, when the reading result of the reading unit includes an error, it is possible to detect the error.

- In the method for determining the authenticity of the display body 10 described above, the computer or server connected to the verifier specifies a reading range to be used for determining the authenticity of the display body 10 from among the reading ranges included in the third pixel group PG3. It is also possible to generate a signal for the verification and output the generated signal to the verifier. Then, the verifier may output an image taken of the reading range specified by the computer or server. In this case, since the reading range is specified for each display 10 to be judged for authenticity, the display It is possible to increase the resistance to counterfeiting that 10 has.

- In the method for determining the authenticity of the display body 10 described above, in addition to the code associated with the arrangement of regions in the pixels 10P of the third pixel group PG3, the light reflected by the specific island region 10P1 of the third pixel group PG3 is used. The color of the display body 10, in other words, whether or not the wavelength of light is a specific wavelength may be included in the conditions for determining the authenticity of the display body 10.

- The example of modification of the third pixel group PG3 described with reference to FIGS. 32 to 42 can be applied to the first pixel group PG1 and the second pixel group PG2. For example, in the first pixel group PG1, one pixel 10P can have an island region having the first uneven structure UE1 and a sea region having the blank structure BL. By arranging the island region within the pixel 10P such that the island region has a similar shape to the pixel 10P and the center of the island region is shifted from the center of the pixel 10P, it is possible to record a code in each pixel 10P. It is possible. Further, for example, in the second pixel group PG2, one pixel 10P can have an island region having the second uneven structure UE2 and a sea region having the blank structure BL. By arranging the island region within the pixel 10P such that the island region has a similar shape to the pixel 10P and the center of the island region is shifted from the center of the pixel 10P, it is possible to record a code in each pixel 10P. It is possible.

[Other change examples]
As described above, codes can also be recorded in the first pixel group PG1 and the second pixel group PG2 in the same way as in the third pixel group PG3. For example, when recording a code in the first pixel group PG1, it is possible to apply the configuration described below to the first pixel group PG1. Note that the configuration described below is applicable not only to the first pixel group PG1 but also to the second pixel group PG2 and the third pixel group PG3.

- When the shape and arrangement of the plurality of island regions PG11a are aperiodic, the entropy of the code recorded as the shape and arrangement, in other words, the amount of information, can be made non-zero. Conversely, when the shape and arrangement of the plurality of island regions PG11a are periodic, the self-entropy of the periodic shape and arrangement, in other words, the amount of selection information is zero. Note that in order to cancel reading errors, the display body 10 may record the same code at different locations, or the shape and arrangement of the plurality of island regions PG11a may have a periodicity. In this case, it is generally preferred that the period be sufficiently long. For example, the period can be 16 bits or more, or even 128 bits or more. Further, the code recorded on the display body 10 may be recorded for each code block having a specific data size. The data size of this code block may be 16 bits, 32 bits, 64 bits, 128 bits, 256 bits, or 512 bits. This code block can be recorded in a rectangular or square recording area that includes a plurality of sea-island structures.

- When the island region PG11a has randomness, the entropy of the recorded code is non-zero. In particular, it is preferable that the base 2 entropy is 1 or more. In this case, 1 bit of information can be recorded. Further, this entropy may be 2, 4, 8, 16, 32, or 64 or more. Furthermore, it is generally sufficient for the entropy to be recorded to be less than 128. In other words, it is not necessary to have complete randomness, and it is possible to have a suitably long period. Furthermore, in order to reduce the entropy of information recorded in the code, a hash value generated by a hash function may be recorded as the code. In particular, the hash function may be a cryptographic hash function. This makes it possible to verify the authenticity using cryptography. Further, at this time, the length of the hash value of the cryptographic hash function may be 128 bits or more and 512 bits or less. This hash value makes it even more difficult to forge the display body 10 because the sea-island structure itself is a structure that is difficult to forge, and it is also necessary to decode the code recorded in the sea-island structure. Further, the cryptographic code does not need to be generated using a cryptographic hash function, and codes generated using various public key cryptosystems, private key cryptosystems, or a combination thereof can be used.

10... Display body 10P... Pixel 10R... Relief layer BL... Blank structure PG1... First pixel group PG11a, PG12a, PG21a, PG22a... Island area PG11b, PG12b, PG21b, PG22b, PG31c... Sea area PG2... Second pixel group PG3 ...Third pixel group PG31a...First island region PG31b...Second island region PIC1...First image PIC2...Second image UE1...First uneven structure UE2...Second uneven structure UEB...Uneven structure

Claims (6)

A display body comprising a relief layer on which an uneven structure is formed,
The angle formed by the plane on which the relief layer spreads and the plane including the viewer's line of sight is the viewing angle, and the display body is capable of displaying the first image and the second image at mutually different viewing angles. ,
When viewed from a viewpoint facing a plane on which the relief layer spreads, a plurality of pixels are spread over the relief layer, and the plurality of pixels include a first pixel group, a second pixel group, and a third pixel group. ,
Each pixel of the first pixel group has a first uneven structure and does not have a second uneven structure,
Each pixel of the second pixel group includes the second uneven structure and does not include the first uneven structure,
Since the period in the first uneven structure and the period in the second uneven structure are different from each other, the first reflection angle in the first uneven structure and the second reflection angle in the second uneven structure are different from each other. can be,
Each pixel of the third pixel group includes the first uneven structure and the second uneven structure,
The first uneven structure has a wave shape that repeats periodically along the first direction in a cross section perpendicular to the plane in which the relief layer spreads,
The second uneven structure has a wave shape that repeats periodically along the second direction in a cross section perpendicular to the plane in which the relief layer spreads,
The first image is formed by each pixel in the first pixel group and each pixel in the third pixel group, and the second image is formed by each pixel in the second pixel group and each pixel in the third pixel group. The first image and the second image are displayed at different observation angles due to the first reflection angle and the second reflection angle being different from each other,
Each pixel of the first pixel group has a sea-island structure having a plurality of island regions with at least one of non-periodic shape and arrangement in a plan view facing the plane on which the relief layer spreads, and has a sea region and a plurality of island regions. One of the island regions has the first uneven structure and the other has the blank structure,
In each pixel included in the first pixel group, the shape of the plurality of island regions is different from the shape of the plurality of island regions in the other pixels, and the arrangement of the plurality of island regions is different from the shape of the plurality of island regions in the other pixels. A display body that satisfies at least one of the following: different from the arrangement of the plurality of island regions in the pixels. The first uneven structure reflects light included in the visible light region in a specular reflection direction by waveguide mode resonance in the first uneven structure,
The display according to claim 1, wherein the island region has the first uneven structure, and the sea region has the blank structure. the blank structure reflects light in a specular direction;
The ratio of the total area of the first uneven structure included in the first pixel group to the total area of the first pixel group is the ratio of the first uneven structure included in the third pixel group to the total area of the third pixel group. The display body according to claim 2, which is larger than the ratio of the total area of the structure. The blank structure has an uneven structure,
The uneven structure of the blank structure has a wavy shape in a cross section perpendicular to a plane on which the display body spreads, and a period in the uneven structure of the blank structure is equal to or less than a wavelength of visible light, and the blank structure The display body according to any one of claims 1 to 3, wherein the height of the uneven structure is larger than the period, so that the blank structure transmits light incident on the blank structure. Each pixel of the second pixel group has a sea-island structure having a plurality of island regions in which at least one of the shape and arrangement is aperiodic in the planar view, and one of the sea region and the island region is located in the second pixel group. The display body according to any one of claims 1 to 4, wherein the display body has two concavo-convex structures, and the other has a blank structure. Each pixel of the third pixel group has a sea-island structure having a plurality of island regions having at least one of aperiodic shape and arrangement in the planar view, and the island region has the first uneven structure. The display according to any one of claims 1 to 5, comprising an island region and an island region having the second uneven structure, and the sea region has a blank structure.