JP2019117289A - Display body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display body capable of visually recognizing images having different appearances depending on an observation condition, and enhancing wavelength selectivity of an image by reflected light or transmitted light, and a device with a display body. SOLUTION: The display body includes a support portion 11 having a reference surface, and a plurality of periodic elements 11T arranged in a two-dimensional lattice shape having a sub-wavelength period on the reference surface, and a convex portion protruding from the reference surface, or A surface including a region surrounding the periodic element 11T on the reference surface and a surface of the periodic element 11T, the periodic structure including a periodic element 11T that is one of the concave portions that are recessed from the reference surface. The metal layers 23 and 42 located on the surface of the periodic structure and having a shape that follows the surface shape of the periodic structure are provided, and the planar shape of the periodic element is a polygon. [Selection diagram] Figure 4

Description

  The present invention relates to a display body.

  The display adds a visual effect different from that of the printed material to the image shown by the display by utilizing interference of light by the diffraction grating or the multilayer film, etc. (see, for example, Patent Document 1). The display object is difficult to forge an article, for example, by being provided for an article that is required to be difficult to forge, such as authentication documents such as a passport and a license, and securities such as a gift certificate and a check Enhance sex. In addition, the display body enhances the design of the article by being provided to the articles around the person.

  The diffraction grating included in the display includes, for example, a transparent resin layer and a metal layer such as aluminum located on the resin layer. For example, the shape of the diffraction grating represented by a mathematical function having a sinusoidal secondary structure has a metal layer thinner than the other portions in the inclined portion of the diffraction grating, and the structural difference between the inclined portions Adds a difference in transmittance or reflectance to the metal layer. Then, it is possible to represent in gray scale, and to represent different colors of the reflected image and the transmitted image (see, for example, Patent Document 1). The difference between the reflected image and the transmitted image also makes it possible to determine the authenticity of the article to which the display is attached.

Patent No. 5124272 specification

  In order to further increase the difficulty of forgery and the design, it is preferable that one display body can form images of different appearances according to the conditions of observation. For example, a display body in which images of different colors are visually recognized in the observation of the surface of the display body and an observation of the back surface, or a color different from each other in observation of reflected light and observation of transmitted light on one surface of the display body There is a demand for a display body in which an image of the object is visually recognized.

  In addition, the shape of the diffraction grating represented by a mathematical function having a sinusoidal secondary structure requires high symmetry in the height direction of the structure in the diffraction grating, that is, in the front and back direction in the display body. As a result, the difference in color between the image observed from the front surface of the display and the image observed from the back of the display is also slight, and the front and back of the display can be determined based on these visual recognitions. Is also difficult.

  Furthermore, the image by the reflected light and transmitted light visually recognized by the surface and back surface of the display body formed from the said conventional diffraction grating has the subject that a color is pale and wavelength selectivity is low.

  An object of the present invention is to provide a display capable of visually recognizing images of different appearances according to the condition of observation, and capable of enhancing the wavelength selectivity of the image by the reflected light or the transmitted light.

  One aspect of the present invention for solving the above-mentioned problems is a support portion having a reference surface, and a plurality of periodic elements arranged in a two-dimensional lattice shape having a sub-wavelength period in the reference surface, A periodic structure body which is a dielectric comprising the periodic element which is any of a projecting convex portion or a concave portion which is recessed from the reference surface, an area surrounding the periodic element in the reference surface, and the periodic element A metal layer located on the surface of the periodic structure that is a surface including a surface and having a shape that follows the surface shape of the periodic structure, and the planar shape of the periodic element is a polygon It is a display body.

  In addition, at least one interior angle of the polygon may be an acute angle.

  Further, at least a part of the adjacent periodic element sets among the plurality of periodic elements may be arranged such that the acute angles face each other.

  Furthermore, in the set of periodic elements in which the acute angles face each other, the distance between the centers of the periodic elements may be a sub-wavelength.

  In addition, the plurality of periodic elements may be arranged to form any one of a hexagonal symmetric array, a hexagonal array, or a square array in a plan view.

  In addition, a first lattice layer having a thickness of 10 nm to 200 nm, a second lattice layer having a thickness of 10 nm to 200 nm, and an intermediate lattice thicker than the first lattice layer and the second lattice layer. A layer, the intermediate lattice layer sandwiched between the first lattice layer and the second lattice layer in the thickness direction is included on the reference plane, and the first lattice layer is formed in an island arrangement The plurality of first dielectric layers arranged in a row, and the first metal layer having a mesh shape surrounding each of the first dielectric layers, wherein the intermediate lattice layer is formed of a plurality of first intermediate dielectrics arranged in an island arrangement. And a second intermediate dielectric layer having a network shape surrounding each first intermediate dielectric layer and having a dielectric constant lower than that of the first intermediate dielectric layer; The layer comprises a plurality of second metal layers arranged in an island arrangement, and a second dielectric layer having a mesh shape surrounding each second metal layer, The period element is the convex portion, and the first dielectric layer and the first intermediate dielectric layer constitute the periodic element, and the first metal layer and the second metal layer form the metal layer. And the volume ratio of the first metal layer in the first lattice layer is greater than the volume ratio of the second metal layer in the second lattice layer, and the second metal layer in the second lattice layer And the volume ratio of the first dielectric layer to the structural period of the first dielectric layer, and the structural period of the second metal layer. The ratio of the width of the second metal layer to Y may be 0.25 or more and 0.75 or less.

  Moreover, it may be located in the surface on the opposite side to the surface in contact with the periodic structure in the metal layer, and may have a dielectric layer having a shape that follows the surface shape of the metal layer.

  According to the present invention, it is possible to visually recognize images of different appearances according to the condition of observation in the display body, and it is possible to increase the wavelength selectivity of the image by the reflected light or the transmitted light.

The top view which shows the planar structure in one Embodiment of the display body of this invention. The enlarged view which expands and shows the planar structure of the 1st display area in the display body of this invention. FIG. 5 is a plan view showing the shape of an isolated area in a first display area of the present invention. It is a figure which shows the cross-section of the 1st display area of this invention, and is the III-III sectional view taken on the line of FIG. It is a figure which shows the cross-section of the 1st display area of this invention, and is the IV-IV sectional view taken on the line of FIG. It is a figure which shows the cross-section of the 2nd display area of this invention, and is the VV sectional view taken on the line of FIG. Sectional drawing which shows the other example of the cross-section of the 1st display area of this invention. The effect | action figure which shows the effect | action of the display body of this invention by the reflection observation by surface side, and the transmission observation by back side. The action view which shows the effect | action of the display body of this invention by reflection observation by a back surface side, and transmission observation by the surface side. Sectional drawing which expands and shows an example of a part of cross-section in the 1st display area of this invention. Sectional drawing which expands and shows a part of cross-section in the 1st display area of the modification of one Embodiment of this invention. Sectional drawing which expands and shows a part of cross-section in the 2nd display area of the modification of one Embodiment of this invention. Sectional drawing which expands and shows a part of cross-section in the 1st display area of the modification of one Embodiment of this invention.

  Hereinafter, the display body according to the present invention will be described in detail by the illustrated embodiment. In addition, a display body may be used for the purpose of raising the difficulty of forgery of articles | goods, may be used for the purpose of improving the designability of articles | goods, and may be used for these purposes. For the purpose of enhancing the difficulty of counterfeiting goods, the display body may be, for example, authentication documents such as passports and licenses, securities such as gift certificates and checks, cards such as credit cards and cash cards, bills, etc. It is pasted. Also, for the purpose of enhancing the design of the article, the display body may be, for example, a decorative article to be worn, an article carried by the user, an article to be placed on like a furniture or home appliance, a wall or a door It is attached to a structure etc.

  As FIG. 1 shows, surface 10S which a display body has is divided into 1st display area 10A and 2nd display area 10B. The cross-sectional structure of the first display area 10A and the cross-sectional structure of the second display area 10B are different from each other. The first display area 10A is an area on the surface 10S in which characters, figures, symbols, patterns, pictures and the like are drawn, and in FIG. 1, for example, an area in which a star-shaped figure is drawn.

[Display body structure]
First, the configuration of the first display area 10A will be described below.
As shown in FIG. 2, the first display area 10A includes a plurality of isolated areas A2 and a single peripheral area A3 surrounding each isolated area A2 when viewed from the direction facing the surface 10S of the display body. In FIG. 2, for convenience of describing the isolated area A2, each isolated area A2 is shown with a dot.

  Each isolated region A2 is arranged in a two-dimensional lattice shape having a sub-wavelength period. The isolated regions A2 can be arranged side by side in a hexagonally symmetric arrangement along the surface 10S, as shown in FIG. 2 as an example. The hexagonal symmetric arrangement is an arrangement in which a plurality of isolated regions A2 are arranged at each vertex of a unit array LT which is a regular hexagon having a length XT of one side. The isolated region A2 arranged at each vertex of the unit array LT is shared by the adjacent unit arrays LT with the structure period PT. The unit array LT may be a polygon, and the isolated regions A2 may be arranged in a square array or a hexagonal array. That is, the isolated area A2 is arranged in an island-like array of any of a hexagonal symmetric array, a square array, and a hexagonal array. The square array is an array in which the isolated area A2 is located at each vertex of the square unit array LT, and the hexagonal array is an array in which the isolated area A2 is located at each vertex of the equilateral triangle unit array LT.

  As shown in FIG. 3, the isolated area A2 is a polygon in which at least one interior angle A1 is an acute angle, and at least a part of a set of adjacent isolated areas A2 among the plurality of isolated areas A2 is an acute angle. The inner angles A1 are arranged to face each other. Further, in a set of isolated areas A2 in which the internal angles A1 face each other, it is preferable that the distance between the centers (geometrical centers or centers of gravity) of the isolated areas A2 be sub-wavelengths. When the isolated region A2 is an equilateral triangle, the structure period PT is preferably not less than 1 and not more than 5 times the width WT of the equilateral triangle (the distance between the inner angle A1 and the side opposite to the inner angle A1). It is a sub wavelength period of 400 nm or more and 800 nm or less which is a wavelength. It is preferable that each isolated area A2 be disposed so as to face the inner angle A1 of the adjacent isolated area A2 where the inner angle A1 is adjacent.

  As FIG. 4 shows, a display body is provided with the transparent support part 11 which permeate | transmits the light of visible region. The wavelength of light in the visible region is 400 nm or more and 800 nm or less. The support portion 11 is common to the first display area 10A and the second display area 10B. The cross-sectional structure of the support 11 may be a single layer structure or a multilayer structure.

  The material which comprises the support part 11 is a dielectric, for example, resin, such as photocurable resin, and inorganic materials, such as quartz. From the viewpoints of easily obtaining the flexibility required to attach the display to the article and the high degree of freedom of the optical characteristics that can be added to the support 11, the material constituting the support 11 is resin. Is preferred. The refractive index of the support portion 11 is higher than that of the air layer, and is, for example, 1.2 or more and 1.7 or less.

  The first display area 10 </ b> A includes a first lattice layer 21, an intermediate lattice layer 31, and a second lattice layer 41 in order from the layer closer to the support portion 11. The intermediate lattice layer 31 is sandwiched between the first lattice layer 21 and the second lattice layer 41. The surface of the support 11 on which the first grating layer 21 is located is the surface of the support 11, and the side on which the first grating layer 21 is located with respect to the support 11 is the surface of the structure. On the contrary, the side where the support portion 11 is located with respect to the first lattice layer 21 is the back side in the structure.

[First lattice layer 21]
The first grating layer 21 is located on the surface of the support portion 11. The first lattice layer 21 comprises a plurality of first dielectric layers 22 and a single first metal layer 23. Each first dielectric layer 22 is formed in a shape corresponding to the isolated area A2 at a position corresponding to the isolated area A2 when viewed from the direction facing the surface 10S of the display body. The single first metal layer 23 is located in the peripheral area A3 when viewed from the direction opposite to the surface 10S. The plurality of first dielectric layers 22 can be arranged along the surface 10S, for example, in a hexagonal symmetrical arrangement, a square arrangement, or an island arrangement of hexagonal arrangement.

  Each first dielectric layer 22 is a structure protruding from the surface of the support 11. Each first dielectric layer 22 is, for example, integral with the support 11. Alternatively, each first dielectric layer 22 has, for example, a boundary with the surface of the support 11 and is separate from the support 11.

  The first metal layer 23 has a mesh shape surrounding each of the first dielectric layers 22 one by one as viewed from the direction facing the surface 10S. In the first lattice layer 21, a single first metal layer 23 is an optical sea component in which free electrons are spread, and each first dielectric layer 22 is an island component distributed in the sea component. .

  The period in which the first dielectric layer 22 is located is the sum of the shortest width WP of the first dielectric layers 22 adjacent to each other and the width WT of the first dielectric layers 22 when viewed from the direction facing the surface 10S. And the structural period PT.

  The ratio of the width WT of the first dielectric layer 22 to the structural period PT is not less than 0.25 and not more than 0.75. The ratio of the width WT of the first dielectric layer 22 to the structural period PT is preferably such that the processing accuracy of the first grating layer 21 can be obtained and that plasmon resonance is easily generated in the first grating layer 21. , 0.40 or more and 0.60 or less. When the planar shape of the first dielectric layer 22 is an equilateral triangle, the structural period PT is not less than 1 and not more than 5 times the width WT of the first dielectric layer 22, and is 400 nm or more which is a wavelength in the visible region. It is a sub wavelength period of 800 nm or less.

  The thickness of the first lattice layer 21 is preferably 10 nm or more and 200 nm or less. The thickness of the first lattice layer 21 can be obtained in view of the fact that the processing accuracy of the first lattice layer 21 can be obtained, that the plasmon resonance is easily generated in the first lattice layer 21, and the color of the image by each observation becomes clear. The thickness is preferably 10 nm or more and 100 nm or less.

[Intermediate lattice layer 31]
An intermediate lattice layer 31 is located on the first lattice layer 21. The thickness of the intermediate lattice layer 31 is thicker than the thickness of the first lattice layer 21. From the viewpoint of obtaining the processing accuracy of the intermediate lattice layer 31, the thickness of the intermediate lattice layer 31 is preferably 150 nm or less.

  The intermediate lattice layer 31 comprises a plurality of first intermediate dielectric layers 32 and a single second intermediate dielectric layer 33. Each first intermediate dielectric layer 32 is formed in a shape corresponding to the isolated area A2 at a position corresponding to the isolated area A2 when viewed from the direction facing the surface 10S. The single second intermediate dielectric layer 33 is located in the peripheral area A3 as viewed from the direction opposite to the surface 10S. The plurality of first intermediate dielectric layers 32 can be arranged along the surface 10S, for example, in a hexagonal symmetric arrangement, a square arrangement, or an island arrangement of hexagonal arrangement.

  Each first intermediate dielectric layer 32 is a structure protruding from the first dielectric layer 22. Each first intermediate dielectric layer 32 is, for example, integral with the first dielectric layer 22. Alternatively, each first intermediate dielectric layer 32 has, for example, a boundary with the first dielectric layer 22 and is separate from the first dielectric layer 22. The period in which the first intermediate dielectric layer 32 is located, as seen from the direction facing the surface 10S, is the sum of the shortest width WP and the width WT, as in the first dielectric layer 22, and is the structural period PT. . The ratio of the width WT of the first intermediate dielectric layer 32 to the structural period PT is not less than 0.25 and not more than 0.75. The ratio of the width WT of the first intermediate dielectric layer 32 to the structural period PT is preferably 0.40 or more and 0.60 or less. When the planar shape of the first intermediate dielectric layer 32 is an equilateral triangle, the structural period PT is 1 to 5 times the width WT of the first intermediate dielectric layer 32 and is a wavelength in the visible region. It is a sub wavelength period of 400 nm or more and 800 nm or less.

  The second intermediate dielectric layer 33 has a mesh shape surrounding each first intermediate dielectric layer 32 one by one, as viewed from the direction opposite to the surface 10S. In the intermediate lattice layer 31, the single second intermediate dielectric layer 33 is structurally and optically a sea component, and each first intermediate dielectric layer 32 is structurally and optically an island component. The second intermediate dielectric layer 33 is an air layer or a resin layer, and has a dielectric constant lower than that of the first intermediate dielectric layer 32.

[Second lattice layer 41]
The second lattice layer 41 is located on the intermediate lattice layer 31. The thickness of the second lattice layer 41 is preferably 10 nm or more and 200 nm or less, and the thickness of the second lattice layer 41 is thinner than the thickness of the intermediate lattice layer 31. The thickness of the second lattice layer 41 can be obtained from the viewpoints of obtaining the processing accuracy of the second lattice layer 41, easily causing plasmon resonance in the second lattice layer 41, and clarifying the color of the image by each observation. The thickness is preferably 10 nm or more and 100 nm or less.

  The second lattice layer 41 comprises a plurality of second metal layers 42 and a single second dielectric layer 43. Each second metal layer 42 is formed in a shape corresponding to the isolated area A2 at a position corresponding to the isolated area A2 when viewed from the direction facing the surface 10S. The position of the single second dielectric layer 43 is included in the peripheral region A3 as viewed from the direction opposite to the surface 10S. The plurality of second metal layers 42 can be arranged along the surface 10S, for example, in a hexagonal symmetric arrangement, a square arrangement, or an island arrangement of hexagonal arrangement.

  Each second metal layer 42 is a structure overlapping the top surface of the first intermediate dielectric layer 32. Each second metal layer 42 has a boundary with the first intermediate dielectric layer 32 and is separate from the first intermediate dielectric layer 32. The period in which the second metal layer 42 is located, as seen from the direction facing the surface 10S, is the sum of the shortest width WP and the width WT, as in the first dielectric layer 22, and is the structural period PT. The ratio of the width of the second metal layer 42 to the structural period PT is not less than 0.25 and not more than 0.75. Further, the ratio of the width of the second metal layer 42 to the structural period PT is preferably 0.40 or more and 0.60 or less. When the planar shape of the second metal layer 42 is an equilateral triangle, the structural period PT is 1 to 5 times the width WT of the second metal layer 42, and is 400 nm to 800 nm which is a wavelength in the visible region. Sub-wavelength period of

  The second dielectric layer 43 has a mesh shape surrounding each second metal layer 42 one by one as viewed from the direction facing the surface 10S. In the second lattice layer 41, the single second dielectric layer 43 is an optical sea component having less free electrons compared to the second metal layer 42, and each second metal layer 42 is a sea component. It is an island component distributed in The second dielectric layer 43 is an air layer or a resin layer and has a dielectric constant lower than that of the first intermediate dielectric layer 32.

  The volume ratio of the first metal layer 23 which is a sea component in the first lattice layer 21 is larger than the volume ratio of the second metal layer 42 which is an island component in the second lattice layer 41. Further, the volume ratio of the second metal layer 42 which is an island component in the second lattice layer 41 is larger than the volume ratio of the metal material in the intermediate lattice layer 31.

  The structure formed of the first dielectric layer 22 and the first intermediate dielectric layer 32 is an example of a periodic element, and the convex portion 11 T protruding from the reference surface with the surface of the support portion 11 as the reference surface. It is also. The structure formed of the support portion 11, the first dielectric layer 22, and the first intermediate dielectric layer 32 is an example of a periodic structure. Further, the layer formed of the first metal layer 23 and the second metal layer 42 can be regarded as a metal layer having a shape in which the shape of the entire layer follows the surface shape of the periodic structure. The surface of the periodic structure is a surface including an area surrounding each periodic element in the reference surface and the surface of each periodic element.

  As shown in FIG. 5, in the peripheral area A3, the first metal layer 23 of the first lattice layer 21, the second intermediate dielectric layer 33 of the intermediate lattice layer 31, and the The second dielectric layer 43 of the two lattice layer 41 is located. The second intermediate dielectric layer 33 is sandwiched between the first metal layer 23 and the second dielectric layer 43.

  As shown in FIG. 6, the second display area 10 </ b> B does not include the first lattice layer 21, the intermediate lattice layer 31, and the second lattice layer 41 described above on the support portion 11. That is, the second display region 10B transmits light in the visible region in accordance with the light transmittance of the support portion 11.

  The second display area 10B may include a layer different from the first display area 10A on the support portion 11. The second display area 10B may include, for example, only the first dielectric layer 22. In addition, the second display region 10B may include, for example, only a single metal layer made of the same material as that of the first metal layer 23. The layer configuration in the second display area 10B is appropriately selected in response to a request for an image displayed by the second display area 10B.

  Further, as described above, the cross-sectional structure of the support 11 may be a multilayer structure, and each first dielectric layer 22 may not have a boundary with the support 11. FIG. 7 shows a structure in which the support 11 is composed of two layers, and of these layers, the layer on the surface side of the support 11 is integral with each first dielectric layer 22. That is, the support part 11 is provided with the base material 11a and the intermediate | middle layer 11b, and the intermediate | middle layer 11b is located in the surface side with respect to the base material 11a. Each first dielectric layer 22 protrudes from the intermediate layer 11 b, and each first dielectric layer 22 and the intermediate layer 11 b are integrated.

[Optical configuration of display body]
Next, the optical configuration of the display will be described.
Here, the surface 10S of the display body and the back surface 10T of the display body are in contact with the air layer, and each of the second intermediate dielectric layer 33 and the second dielectric layer 43 is an air layer, or The structure which is a resin layer having a refractive index close to that of the air layer will be described as an example.
As FIG. 8 shows, the refractive index of the support part 11 is the magnitude | size which was controlled by the dielectric material, Comprising: It is larger than the refractive index of an air layer.

  The refractive index of the first dielectric layer 22 is higher than the refractive index of the air layer, and the refractive index of the first metal layer 23 is lower than the refractive index of the air layer. The refractive index of the first grating layer 21 is approximated to an averaged size by the refractive index of the first metal layer 23 and the refractive index of the first dielectric layer 22. When the ratio of the width WT of the first dielectric layer 22 to the structural period PT is 0.25 or more and 0.75 or less, and the planar shape of the first dielectric layer 22 is an equilateral triangle, the structural period PT is the first Since the width WT of the dielectric layer 22 is not less than 1 and not more than 5 times, the refractive index of the first grating layer 21 is ultimately a size controlled by the first metal layer 23 which is a sea component, It is sufficiently lower than the refractive index of the air layer.

  The refractive index of the first intermediate dielectric layer 32 is higher than the refractive index of the air layer, and the refractive index of the second intermediate dielectric layer 33 is equal to the refractive index of the air layer, or higher than the refractive index of the air layer. high. The refractive index of the intermediate grating layer 31 is approximated to an averaged size by the refractive index of the second intermediate dielectric layer 33 and the refractive index of the first intermediate dielectric layer 32. When the ratio of the width WT of the first intermediate dielectric layer 32 to the structural period PT is 0.25 or more and 0.75 or less, and the planar shape of the first intermediate dielectric layer 32 is an equilateral triangle, the structural period PT is Since the first intermediate dielectric layer 32 has a width one to five times the width WT of the first intermediate dielectric layer 32, the refractive index of the intermediate lattice layer 31 is ultimately determined by the second intermediate dielectric layer 33 which is a sea component. And higher than the refractive index of the air layer and close to the refractive index of the air layer.

  The refractive index of the second metal layer 42 is lower than the refractive index of the air layer, and the refractive index of the second dielectric layer 43 is equal to the refractive index of the air layer or higher than the refractive index of the air layer. The refractive index of the second grating layer 41 is approximated to an averaged size by the refractive index of the second dielectric layer 43 and the refractive index of the second metal layer 42. When the ratio of the width WT of the second metal layer 42 to the structural period PT is 0.25 or more and 0.75 or less, and the planar shape of the second metal layer 42 is an equilateral triangle, the structural period PT is the second metal layer The refractive index of the second lattice layer 41 is eventually controlled by the second dielectric layer 43 which is a sea component, since it is 1 to 5 times the width WT of 42, and the air layer is Lower than the refractive index of the above, and close to the air layer.

[Surface reflection observation, back surface transmission observation]
Here, the white light L1 entering the second lattice layer 41 from the outside of the display body enters the second lattice layer 41 from the air layer, and enters the intermediate lattice layer 31 from the second lattice layer 41. The light L1 incident on the second grating layer 41 enters the second grating layer 41 having a refractive index close to that of the air layer from the air layer, so Fresnel reflection is performed at the interface between the air layer and the second grating layer 41. It is hard to occur. In addition, since light incident on the intermediate grating layer 31 enters the intermediate grating layer 31 having a refractive index close to the air layer from the second grating layer 41 having a refractive index close to the air layer, At the interface between the lattice layer 41 and the intermediate lattice layer 31, it is difficult for Fresnel reflection to occur.

  On the other hand, since the structural period PT of the second metal layer 42 is a sub-wavelength period equal to or less than the wavelength in the visible region, plasmon resonance occurs in the second grating layer 41. Plasmon resonance is a phenomenon in which part of light incident on the second grating layer 41 is combined with collective vibration of electrons. A part of the light L 1 incident on the second lattice layer 41 is converted to surface plasmons by plasmon resonance in the second lattice layer 41, and the surface plasmons pass through the second lattice layer 41. The surface plasmons transmitted through the second lattice layer 41 are converted to light and emitted. The wavelength range of the light EP 2 emitted by the second grating layer 41 due to the plasmon resonance is a specific wavelength range depending on the grating structure and material including the structure period PT of the second metal layer 42. As a result, the second grating layer 41 transmits to the intermediate grating layer 31 part of the light in the wavelength region of the light incident on the second grating layer 41.

  In addition, since the structural period PT of the first dielectric layer 22 is also a sub-wavelength period equal to or less than the wavelength in the visible region, plasmon resonance also occurs in the first grating layer 21. That is, part of the light incident on the first lattice layer 21 is also converted to surface plasmons by plasmon resonance in the first lattice layer 21, and the surface plasmons are transmitted through the first lattice layer 21 and reconverted to light. It is emitted. The wavelength range of the light EP1 emitted by the first grating layer 21 due to the plasmon resonance is a specific wavelength range depending on the grating structure and material including the structure period PT of the first dielectric layer 22. As a result, the first grating layer 21 transmits the light of a part of the wavelength region of the light incident on the first grating layer 21 to the support 11.

  Furthermore, the first dielectric layer 22 is a polygon in which at least one of the inner angles is an acute angle, and is disposed at each vertex of the unit array LT which is a regular hexagon having a length XT of one side. Surface plasmons are known to be strongly induced at the tip of the structure. Therefore, when the first dielectric layer 22 is a polygon, the effect appears strongly near the acute angle. In addition, it is known that the optical and coloring characteristics by surface plasmons are influenced by the arrangement shape of a substance that induces surface plasmons such as metal. For example, by changing the arrangement shape to one having high rotational symmetry such as a square arrangement, a hexagonal arrangement, a hexagonal arrangement, etc., the dispersion relation of surface plasmons can be changed, and control such as narrowing the reflection spectrum becomes possible. . Therefore, the bandwidth of absorption is reduced and wavelength selectivity is enhanced.

  As a result, according to surface reflection observation in which the light L1 is made incident to the second grating layer 41 from the outside of the display body and the surface 10S is observed from the surface side of the display body, it is difficult to cause Fresnel reflection at each interface. The generation of strong plasmon resonance in each of the lattice layers and the combination thereof cause a black color or a color close to black to be visually recognized in the first display area 10A.

  On the other hand, according to the back surface transmission observation in which the light L1 is made incident on the second lattice layer 41 from the outside of the display body and the back surface 10T is observed from the back surface side of the display body The colored light LP1, that is, light other than white and black is visually recognized in the first display area 10A. The results of the surface reflection observation and the rear surface transmission observation show the same tendency even when the light quantity of the external light directed to the front surface 10S is higher than the light quantity of the external light directed to the back surface 10T.

[Backside reflection observation, surface transmission observation]
As shown in FIG. 9, white light L1 incident on the support 11 from the outside of the display body enters the support 11 from the air layer and enters the first lattice layer 21 from the support 11. The light L1 incident on the support portion 11 enters the first grating layer 21 having a refractive index lower than that of the air layer from the support portion 11 having an index of refraction higher than that of the air layer. At the interface with the grating layer 21, Fresnel reflection tends to occur. The difference between the refractive index of the support 11 and the refractive index of the first grating layer 21 is larger than the difference of the refractive index between the first grating layer 21 and the intermediate grating layer 31, and the intermediate grating layer 31 And the second grating layer 41 is larger than the refractive index difference.

  On the other hand, part of the light transmitted through the interface between the support portion 11 and the first lattice layer 21 is subjected to plasmon resonance in the first lattice layer 21. Again, the wavelength region of the light EP1 emitted by the first grating layer 21 due to plasmon resonance is a specific wavelength region depending on the grating structure and material including the structural period PT of the first metal layer 23. The light in this wavelength range is not reflected at the interface between the support 11 and the first grating layer 21 but consumed by plasmon resonance. As a result, part of the light in the wavelength region of light incident on the support 11 is reflected at the interface between the support 11 and the first lattice layer 21, and the first lattice layer 21 is incident on the first lattice layer 21. A part of the light in the wavelength range of the light is transmitted to the intermediate grating layer 31.

  In addition, part of the light transmitted through the intermediate lattice layer 31 and incident on the second lattice layer 41 is also subjected to plasmon resonance in the second lattice layer 41. Also here, the wavelength range of the light EP 2 emitted by the second grating layer 41 due to plasmon resonance is a specific wavelength range depending on the grating structure and material including the structure period PT of the second dielectric layer 43. As a result, the second grating layer 41 transmits part of the light in the wavelength region of the light incident on the second grating layer 41 to the air layer.

  Furthermore, the first dielectric layer 22 is a polygon in which at least one of the inner angles is an acute angle, and is disposed at each vertex of the unit array LT which is a regular hexagon having a length XT of one side. Surface plasmons are known to be strongly induced at the tip of the structure. Therefore, when the first dielectric layer 22 is a polygon, the effect appears strongly near the acute angle. In addition, it is known that the optical and coloring characteristics by surface plasmons are influenced by the arrangement shape of a substance that induces surface plasmons such as metal. For example, by changing the arrangement shape to one having high rotational symmetry such as a square arrangement, a hexagonal arrangement, a hexagonal arrangement, etc., the dispersion relation of surface plasmons can be changed, and control such as narrowing the reflection spectrum becomes possible. . Therefore, the band width of absorption is reduced and the wavelength selectivity is enhanced by the hexagonal symmetric arrangement.

  As a result, according to back surface reflection observation in which the light L1 is made incident on the support portion 11 from the outside of the display body and the back surface 10T is observed from the back surface side of the display body, colored light LR by Fresnel reflection at the interface is That is, light LR other than white and black is visually recognized in the first display area 10A. The Fresnel reflection generated at the interface between the support portion 11 and the first grating layer 21 causes a color closer to black to be visually recognized in the first display region 10A in the above-described surface reflection observation.

  On the other hand, in surface transmission observation in which light L1 is made incident on the support portion 11 from the outside of the display body and the surface 10S is observed from the surface side of the display body, the Fresnel reflection and the plasmon resonance in each of the lattice layers The colored light LP2 is viewed in the first display area 10A. The results of the surface transmission observation and the back surface reflection observation show the same tendency even when the light quantity of the external light directed to the back surface 10T is higher than the light quantity of the external light directed to the surface 10S.

[Method of manufacturing display body]
Next, an example of a method of manufacturing a display will be described.
First, the first dielectric layer 22 and the first intermediate dielectric layer 32 are formed on the surface of the support portion 11. The first dielectric layer 22 and the first intermediate dielectric layer 32 are integrally formed as a protrusion protruding from the surface of the support portion 11. The method of forming the protrusion is, for example, a photolithographic method using light or a charged particle beam, a nanoimprint method, and a plasma etching method.

  For example, as shown in FIG. 7, when manufacturing a display having a support 11 composed of a base 11a and an intermediate layer 11b, first, a polyethylene terephthalate sheet is used as the base 11a, and the base 11a is used. Apply UV curable resin to the surface of Next, the surface of the synthetic quartz mold, which is an intaglio, is pressed against the surface of the coating film made of an ultraviolet curable resin, and the surface is irradiated with ultraviolet light. Subsequently, the synthetic quartz mold is released from the cured ultraviolet curable resin. As a result, the unevenness of the intaglio is transferred to the resin on the surface of the base material 11a, and the protrusion composed of the first dielectric layer 22 and the first intermediate dielectric layer 32 and the intermediate layer 11b are formed. In addition, it is also possible to change an ultraviolet curable resin into a thermosetting resin, and it is also possible to change irradiation of an ultraviolet-ray to heating. Moreover, it is also possible to change an ultraviolet curable resin into a thermoplastic resin, and it is also possible to change irradiation of an ultraviolet-ray to heating and cooling.

  Next, the first metal layer 23 and the second metal layer 42 are formed on the surface of the support 11 having the protrusions. The method of forming the first metal layer 23 and the second metal layer 42 is, for example, a vacuum evaporation method or a sputtering method. Thereby, the first lattice layer 21 partitioned by the top surface of the first metal layer 23 is formed, and the second lattice layer 41 partitioned by the top surface of the second metal layer 42 is formed, and these first lattice layers are formed. An intermediate lattice layer 31 sandwiched between the first and second lattice layers 41 is formed.

[Configuration Example of First Display Area]
As FIG. 10 shows, as the thickness T2 of the first metal layer 23 is thicker, the light intensity by Fresnel reflection is larger at the interface between the first lattice layer 21 and the support portion 11, and the image in the back surface reflection observation is Brightness is increased. As the internal angle A1 which is the acute angle of the first dielectric layer 22 faces each other and the ratio of the width WT of the first dielectric layer 22 to the structural period PT is smaller, this also increases the lightness of the image in the back reflection observation. .

  Further, as the thickness T2 of the first metal layer 23 increases, the intensity of light transmitted from the back surface 10T to the surface 10S decreases, and the color in surface reflection observation approaches black. As the internal angle A1 which is the acute angle of the first dielectric layer 22 faces each other and the ratio of the width WT of the first dielectric layer 22 to the structural period PT is smaller, the color in the surface reflection observation is also blacker Approach to

  And, when the thickness T2 of the first metal layer 23 is 10 nm or more and the ratio of the width WT of the first dielectric layer 22 to the structural period PT is 0.75 or less, or the first dielectric layer If the planar shape of 22 is an equilateral triangle, the structural period PT is not more than 5 times the width WT of the first dielectric layer 22, and the sub wavelength period is 400 nm or more and 800 nm or less which is the wavelength in the visible region In the above-mentioned observation for judging the front and back of the, its accuracy is sufficiently obtained.

  On the other hand, the thinner the thickness T2 of the first metal layer 23 and the thinner the thickness T4 of the second metal layer 42, the greater the intensity of light transmitted through them in front surface transmission observation and back surface transmission observation. The intensity of light transmitted through the display body also increases as the acute angle of the first dielectric layer 22 faces the inside angle A1 and the ratio of the width WT of the first dielectric layer 22 to the structural period PT increases.

  The thickness T2 of the first metal layer 23 and the thickness T4 of the second metal layer 42 are 200 nm or less, and the ratio of the width WT of the first dielectric layer 22 to the structural period PT is 0.25. Or the planar shape of the first dielectric layer 22 is an equilateral triangle, the structure period PT is at least one time the width WT of the first dielectric layer 22, and the wavelength in the visible region is 400 nm or more If the sub-wavelength period is 800 nm or less, an image visually recognized in front surface transmission observation and an image visually recognized in back surface transmission observation become clear to such an extent that they can be visually recognized.

  The sum of the thickness T2 of the first dielectric layer 22 and the thickness T3 of the first intermediate dielectric layer 32 is the sum of the width WT of the first dielectric layer 22 and the shortest width WP. It is preferable that it is smaller than that. Further, it is more preferable that the sum of the thickness T2 of the first dielectric layer 22 and the thickness T3 of the first intermediate dielectric layer 32 be smaller than half of the structural period PT.

  With such a configuration, in the resin structure in which the first dielectric layer 22 and the first intermediate dielectric layer 32 are integrated, it is possible to increase the accuracy of the shape of the structure, and the first dielectric The protrusion 11T formed of the body layer 22 and the first intermediate dielectric layer 32 is prevented from falling on the surface of the support 11.

A metal material whose real part of the complex dielectric constant at a wavelength in the visible range has a negative value tends to cause plasmon resonance in the first lattice layer 21 and the second lattice layer 41 using it. Then, it is preferable that the material which comprises the 1st metal layer 23 is a material whose real part of the said complex dielectric constant is a negative value. It is preferable that the material forming the second metal layer 42 also be a material whose real part of the complex dielectric constant is a negative value.
The material which comprises these 1st metal layer 23 and the 2nd metal layer 42 is aluminum, silver, gold, indium, tantalum etc., for example.

  As described in the above-described manufacturing method, the first metal layer 23 and the second metal layer 42 are metal layers for the support portion 11 on which the first dielectric layer 22 and the first intermediate dielectric layer 32 are formed. Can be formed in a single step.

  In this case, the metal particles flying from the film forming source adhere to the surface of the support portion 11 with a predetermined angular distribution. As a result, the width W4 of the second metal layer 42 is slightly larger than the width WT of the first intermediate dielectric layer 32, and the shortest width WP4 of the second metal layers 42 adjacent to each other is slightly larger than the shortest width WP It becomes smaller. At this time, the ratio of the width W4 of the second metal layer 42 to the structural period PT is not less than 0.25 and not more than 0.75. When the planar shape of the first intermediate dielectric layer 32 is an equilateral triangle, the structural period PT is not less than 1 and not more than 5 times the width WT of the first intermediate dielectric layer 32 and is 400 nm which is a wavelength in the visible region. The sub wavelength period is 800 nm or less. Incidentally, the periphery of the first intermediate dielectric layer 32 in the first metal layer 23 is affected by the shadow effect of the second metal layer 42, and the portion closer to the first intermediate dielectric layer 32 is thinner.

  Further, in the structure formed by the film forming method, an intermediate metal layer 32A which is a metal layer continuous with the second metal layer 42 is also formed on the side surface of the first intermediate dielectric layer 32.

  The intermediate metal layer 32 A is sandwiched between the first intermediate dielectric layer 32 and the second intermediate dielectric layer 33. The intermediate metal layer 32A is a structure integral with the second metal layer 42, and the thickness on the side surface of the first intermediate dielectric layer 32 is thinner toward the portion closer to the first metal layer 23.

In the intermediate metal layer 32A, since the structural period PT is a sub-wavelength period, the change of the refractive index in the thickness direction of the second grating layer 41 and the intermediate grating layer 31 is continuous. The intermediate metal layer 32A hardly reflects the light incident on the second lattice layer 41 from the outside of the display, and easily transmits the light to the intermediate lattice layer 31 and the first lattice layer 21. Therefore, in the surface reflection observation described above, a color closer to black is visually recognized in the first display area 10A.
Moreover, in the structure formed by the said film-forming method, the material which comprises the 1st metal layer 23, and the material which comprises the 2nd metal layer 42 are mutually equal.

  Here, as the difference in refractive index between the second dielectric layer 43 and the second metal layer 42 is smaller, the averaged refractive index in the second grating layer 41 corresponds to the second grating layer 41 and the other layers. It is easy to suppress Fresnel reflection at the interface with it. On the other hand, as the difference in refractive index between the first dielectric layer 22 and the first metal layer 23 is larger, the averaged refractive index of the first grating layer 21 is different between the first grating layer 21 and the support portion 11. It is easy to promote Fresnel reflection at the interface.

  Therefore, the first metal layer 23 and the second metal layer 42 have the same refractive index, and the refractive index difference between the first dielectric layer 22 and the first metal layer 23 is the second. If the configuration is larger than the refractive index difference between the dielectric layer 43 and the second metal layer 42, Fresnel reflection at the interface between the second grating layer 41 and the other layers is suppressed, and the first grating layer is formed. It is possible to promote Fresnel reflection at the interface between 21 and other layers.

  The following conditions are satisfied in order to suppress Fresnel reflection at the interface between the second lattice layer 41 and the other layers and to promote Fresnel reflection at the interface between the first lattice layer 21 and the other layers. Is preferred. That is, the refractive index difference between the second dielectric layer 43 and the surface layer, which is a layer in contact with the second dielectric layer 43 on the side opposite to the intermediate lattice layer 31 with respect to the second dielectric layer 43, is The refractive index difference between the first metal layer 23 and the support portion 11 is preferably smaller. The surface layer is, for example, an air layer. The refractive index of the second dielectric layer 43 is more preferably equal to the refractive index of the surface layer.

As mentioned above, according to the said embodiment, the effect listed below is acquired.
(1) Since images having different colors in front surface reflection observation and back surface reflection observation can be visually recognized in the first display area 10A, it is possible to distinguish the front and back of the display body. Moreover, it becomes possible to make judgment of the authenticity of the article attached to the display body easy and to improve the design of the article attached to the display body.

(2) Since images having different colors can be visually recognized in the first display area 10A also in front surface reflection observation and back surface transmission observation, it is possible to enhance the accuracy with respect to the judgment result of the front and back. In addition, since images having different colors can be visually recognized in the first display region 10A also in the back surface reflection observation and the surface transmission observation, it is possible to enhance the accuracy with respect to the judgment result of the front and back.

(3) The size of the structural period PT is a sub-wavelength period that is equal to or less than the wavelength of the visible region, and is a size that suppresses formation of primary diffracted light of light in the visible region. Therefore, it is possible to suppress the rainbow color from being included in the image by back surface reflection observation, front surface transmission observation, and back surface transmission observation, and to make the color of the image by each observation more vivid.

(4) The first dielectric layer 22, the first intermediate dielectric layer 32, and the second metal layer 42 are polygons in which at least one internal angle is an acute angle, and they are disposed at each vertex of the unit array which is a regular hexagon. When this is done, it is possible to increase the wavelength selectivity of the image in each observation.

(5) Since the total of the thickness T2 of the first lattice layer 21 and the thickness T3 of the intermediate lattice layer 31 is such a size that an intaglio such as nanoimprint can be applied, the first dielectric layer 22 and the first dielectric layer 22 It is also possible to integrally form the first intermediate dielectric layer 32.

(6) Since the first dielectric layer 22 and the first intermediate dielectric layer 32 are an integral structure, and the second intermediate dielectric layer 33 and the second dielectric layer 43 are integral, display It also makes it possible to simplify the structure of the body. Furthermore, if the second intermediate dielectric layer 33 and the second dielectric layer 43 are an integral air layer, the structure of the display can be further simplified.
(7) Since the intermediate metal layer 32A has an anti-reflection function, it is possible to make the color of the image visually recognized by surface reflection observation even closer to black.

(8) The color of the first display area 10A can be made unique in each of the surface reflection observation, the back surface reflection observation, and the transmission observation on the front surface or the back surface. Therefore, it is also possible to improve the accuracy in the determination of the authenticity of the article to which the display body is attached.

(9) The color of the first display area 10A can be unique in each of the surface reflection observation, the back surface reflection observation, and the transmission observation on the front surface or the back surface. Therefore, it is possible to make the form of display by the display body more complicated and to improve the design of the display body.

<Modification of the above embodiment>
The above embodiment can be modified as follows.
[Intermediate lattice layer 31]
The first intermediate dielectric layer 32 and the second intermediate dielectric layer 33 can be embodied in respective separate structures. At this time, the second intermediate dielectric layer 33 is preferably a resin layer having a refractive index closer to the refractive index of the air layer than the refractive index of the first intermediate dielectric layer 32.

  The second intermediate dielectric layer 33 and the second dielectric layer 43 can be embodied in respective different structures. At this time, the second intermediate dielectric layer 33 is preferably a resin layer having a refractive index closer to the refractive index of the air layer than the refractive index of the second dielectric layer 43.

[First lattice layer 21]
-As FIG. 11 shows, the 1st dielectric material layer 22 and the 1st intermediate | middle dielectric material layer 32 are comprised as an integral structure. The shape of the convex portion 11T, which is an integral structure, can be embodied in the shape of a cone that protrudes from the surface of the support portion 11. With such a structure, when forming the first dielectric layer 22 and the first intermediate dielectric layer 32, it is possible to smoothly release the intaglio plate for forming the first dielectric layer 22 and the first intermediate dielectric layer 32.

[Second display area 10B]
-As FIG. 12 shows, the 2nd display area 10B can be embodied as a structure provided only with the metal layer 23B in the surface of the support part 11. FIG. At this time, in the surface reflection observation, an image having a black color or a color close to black can be visually recognized in the first display area 10A, and an image having a metallic gloss can be visually recognized in the second display area 10B. be able to. On the other hand, in the back surface reflection observation, as light by Fresnel reflection at the interface between the first lattice layer 21 and the support portion 11, color by light influenced by the wavelength region consumed by plasmon resonance in the first lattice layer 21 An image having a metallic gloss in which only the Fresnel reflection at the interface between the metal layer 23B and the support portion 11 can be made visible in the second display area 10B. It can be made visible.

[Protective layer]
The display further includes a protective layer on the second metal layer 42. At this time, the intensity of Fresnel reflection at the interface between the protective layer and the second metal layer 42 and the accompanying wavelength selectivity of the display vary depending on the refractive index of the protective layer. Then, the material which comprises a protective layer is suitably selected based on the wavelength range which a display body is made to select.

  As shown in FIG. 13, the protective layer 45 can be embodied as a structure integral with the second dielectric layer 43 and the second intermediate dielectric layer 33. At this time, the protective layer 45 is preferably a resin layer with a low refractive index. The low refractive index resin layer has a refractive index closer to the refractive index of the air layer than the refractive index of the first dielectric layer 22 or the refractive index of the first intermediate dielectric layer 32.

[Other forms]
The arrangement of the isolated regions A2 viewed from the direction opposite to the surface 10S of the display body is not limited to the hexagonal symmetric arrangement, the square arrangement, and the hexagonal arrangement, and may be a two-dimensional lattice arrangement. That is, the plurality of first dielectric layers 22 may be arranged in a two-dimensional lattice, and the plurality of first intermediate dielectric layers 32 may be arranged in a two-dimensional lattice. The two metal layers 42 may be arranged in a two-dimensional lattice. In other words, the periodic elements of the periodic structure may be arranged in a two-dimensional lattice with sub-wavelength periods. The two-dimensional grid array is an array in which elements are arranged along each of two intersecting directions in a two-dimensional plane. At this time, the ratio of the width WT to the structure period PT is the ratio of the width WT to the structure period PT in one direction, and the ratio being within the predetermined range means that the periodic elements are aligned in the two directions. For each, the ratio of the width WT to the structure period PT is shown to be within a predetermined range.

  Further, the shape of the isolated area A2 viewed from the direction opposite to the surface 10S of the display body, that is, the planar shape of the periodic element is not limited to a triangle, and may be another polygon such as a square or a rectangle. It may be circular.

  -If the display body has a structure in which plasmon resonance occurs in the first grating layer 21 and the second grating layer 41, the transmitted light passing through the display body is a light of a specific wavelength region corresponding to the structural period PT It becomes. Even when Fresnel reflection occurs at the interface between the second lattice layer 41 and the other layers, and a colored image different from black is visually recognized in the first display region 10A in surface reflection observation, it is possible by plasmon resonance. Because the consumed wavelength region is not included in the reflected light, images of different colors are visually recognized in the surface reflection observation and the back surface transmission observation. Moreover, the image of a mutually different color is visually recognized also by back surface reflection observation and surface transmission observation. Therefore, it is possible to visually recognize images of different colors in the observation of the front surface of the display body and the observation of the back surface, that is, it is possible to visually recognize images of different appearances according to the conditions of observation. Therefore, it is possible to further enhance the difficulty of forgery and the design of the article to which the display body is attached.

  For example, the ratio of the width WT of the first dielectric layer 22 to the structural period PT and the ratio of the width WT of the second metal layer 42 to the structural period PT have values different from 0.25 or more and 0.75 or less. When the planar shape of the first dielectric layer 22 is an equilateral triangle, the structure period PT may have a value different from 1 to 5 times the width WT of the first dielectric layer 22. Further, for example, the relationship between the thicknesses of the first lattice layer 21, the intermediate lattice layer 31, and the second lattice layer 41 may be different from that of the above embodiment.

  The present invention can increase the difficulty of forgery of an item by being provided for an item that is required to be difficult to forge, and can improve the design of an item by being provided for an item around it. Can be used in various displays.

  A2 ... isolated area, A3 ... peripheral area, L1, EP1, EP2, LR, LP1, LP2 ... light, LT ... unit array, XT ... length of one side of unit array, PT ... structure period, T2, T3, T4 ... thickness, W4, WT ... width, WP ... shortest width, 10A ... first display area, 10B ... second display area, 10S ... surface, 10T ... back surface, 11 ... support portion, 11a ... base material, 11b ... middle Layer 11T: convex portion 21: first lattice layer 22: first dielectric layer 23: first metal layer 31: intermediate lattice layer 32: first intermediate dielectric layer 32A: intermediate metal layer 33 second intermediate dielectric layer 41 second lattice layer 42 second metal layer 43 second dielectric layer 45 protective layer

Claims (7)

A supporting portion having a reference surface, and a plurality of periodic elements arranged in a two-dimensional lattice form having a sub-wavelength period in the reference surface, a protrusion protruding from the reference surface or a recess recessed from the reference surface And a surface of the periodic structure which is a surface including a region surrounding the periodic element of the reference surface and a surface of the periodic element. And a metal layer positioned to follow the surface shape of the periodic structure.
The planar shape of the periodic element is a polygon,
Display body. At least one interior angle of the polygon is an acute angle,
The display body according to claim 1. At least a part of the adjacent periodic element sets among the plurality of periodic elements are arranged such that the acute angles of the respective periodic elements face each other,
The display body according to claim 2. In the set of periodic elements where the acute angles face each other, the distance between the centers of the periodic elements is a sub-wavelength,
The display body of Claim 3. The plurality of periodic elements are arranged to form any of a hexagonal symmetric array, a hexagonal array, or a square array in a plan view.
The display body in any one of Claims 1-4. A first grating layer having a thickness of 10 nm or more and 200 nm or less;
A second grating layer having a thickness of 10 nm or more and 200 nm or less;
An intermediate lattice layer thicker than the first lattice layer and the second lattice layer, and the intermediate lattice layer interposed between the first lattice layer and the second lattice layer in the thickness direction; Included on the face,
The first lattice layer includes a plurality of first dielectric layers arranged in an island arrangement, and a first metal layer having a mesh shape surrounding each first dielectric layer,
The intermediate lattice layer has a plurality of first intermediate dielectric layers arranged in an island arrangement, and a mesh shape surrounding each first intermediate dielectric layer, and has a dielectric constant lower than that of the first intermediate dielectric layer. And a second intermediate dielectric layer having
The second lattice layer includes a plurality of second metal layers arranged in an island arrangement, and a second dielectric layer having a mesh shape surrounding each second metal layer,
The periodic element is the convex portion, and the first dielectric layer and the first intermediate dielectric layer constitute the periodic element, and the first metal layer and the second metal layer are the metal layer. Included in
The volume ratio of the first metal layer in the first lattice layer is larger than the volume ratio of the second metal layer in the second lattice layer, and the volume ratio of the second metal layer in the second lattice layer Is larger than the volume ratio of the metal material in the intermediate lattice layer,
The ratio of the width of the first dielectric layer to the structural period of the first dielectric layer and the ratio of the width of the second metal layer to the structural period of the second metal layer are not less than 0.25 and not more than 0.75. Less than
The display body in any one of Claims 1-5. It comprises a dielectric layer located on the surface of the metal layer opposite to the surface in contact with the periodic structure and having a shape that follows the surface shape of the metal layer.
The display body in any one of Claims 1-6.

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