JP5082378B2 - Display and printed matter - Google Patents

Description

  The present invention relates to a forgery prevention technique.

  It is desirable that authentication items such as cash cards, credit cards and passports, and securities such as gift certificates and stock certificates are difficult to counterfeit. Therefore, conventionally, a label that is difficult to counterfeit or counterfeit and is easy to distinguish from counterfeit or counterfeit is attached to such articles in order to prevent counterfeiting.

  In recent years, the distribution of counterfeit products has been regarded as a problem for items other than certified items and securities. Therefore, the opportunity to apply the above-described anti-counterfeiting technology with respect to certified articles and securities is increasing.

  Patent Document 1 describes a display body formed by arranging a plurality of pixels. In this display body, each pixel includes a relief type diffraction grating in which a plurality of grooves are arranged.

  Since this display body displays an image using diffracted light, it cannot be counterfeited using a printing technique or an electrophotographic technique. Therefore, if this display is attached to an article as a label for authenticity determination, it is possible to confirm that the article is genuine by viewing the image displayed by this label. Therefore, an article with this label attached is less likely to be counterfeited than an article without this label attached.

However, the relief-type diffraction grating can be formed relatively easily if there is an apparatus such as a laser. The previous display body changes the display image by changing the incident angle of the illumination light, the observation angle, or the orientation of the display body, but the change is not rich in diversity. Therefore, with the development of technology, the anti-counterfeit effect of the display body is decreasing. Here, the fact that counterfeiting or counterfeiting is difficult, and the fact that it is easy to distinguish from counterfeiting or counterfeiting are called anti-counterfeiting effects.
JP-A-2-72320

  An object of the present invention is to realize a higher anti-counterfeit effect.

According to a first aspect of the present invention, there is provided a reflective layer including a light transmissive first dielectric layer including first and second portions that are adjacent to each other in an in-plane direction and have different thicknesses. The thickness of the one part is set so as to generate constructive interference when light having a wavelength λ ₁ in the visible light wavelength range is repeatedly reflected between one main surface and the other main surface . The thickness of the portion is such that a constructive interference occurs when light having a wavelength λ ₂ in the visible wavelength range different from the wavelength λ ₁ is repeatedly reflected between one main surface and the other main surface. is set, one main surface of the first dielectric layer includes first and second regions respectively corresponding to said first and second portions, said first and second regions of the first and second different heights corresponding to the difference in thickness of the second portion, the in each of the first and second regions A plurality of recesses and / or protrusions are provided over the body, said plurality of recesses and / or protrusions forming the diffraction grating or light scattering structures in each of said first and second regions A characteristic display is provided.

  According to a second aspect of the present invention, there is provided a printed matter comprising a base material, a printed layer formed on the base material, and a display body according to the first side surface supported by the base material. Provided.

  According to the present invention, it is possible to achieve a higher anti-counterfeit effect.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same referential mark is attached | subjected to the component which exhibits the same or similar function, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a plan view schematically showing a display body according to one aspect of the present invention. 2 is a cross-sectional view taken along the line II-II of the display shown in FIG.

  The display body 10 includes a light transmission layer 11 and a reflection layer 12. The reflection layer 12 covers one main surface of the light transmission layer 11. In the example shown in FIG. 2, the light transmission layer 11 side is the front side, and the reflection layer 12 side is the back side.

  The front surface of the light transmission layer 11 is a flat surface. On the back surface of the light transmission layer 11, a plurality of convex portions and / or concave portions are provided at positions corresponding to the regions R1 to R5. These convex portions and / or concave portions diffract and / or scatter illumination light, for example. The display body 10 displays an image using the diffracted light and / or scattered light.

  For example, these convex portions and / or concave portions form a relief type diffraction grating and / or a light scattering structure. Typically, these convex portions and / or concave portions form a relief type diffraction grating, or form a relief type diffraction grating and a relief type light scattering structure. In the following description, the case where these convex portions and / or concave portions form a relief type diffraction grating will be mainly described as an example.

  The term “diffraction grating” means a structure that generates a diffracted wave by irradiating illumination light such as natural light. For example, in addition to a normal diffraction grating in which a plurality of grooves are arranged in parallel and at equal intervals, it is recorded on a hologram. The interference fringes made are also included. Further, the groove or a portion sandwiched between the grooves is referred to as a “lattice line”.

  The convex portions and / or concave portions forming the diffraction grating are regularly arranged in a region on the back surface of the light transmission layer 11. The region where the uniform diffraction grating is formed is formed to have a width of 100 μm or less, for example. When this width is reduced, it becomes difficult to visually identify the configuration of the region, and an image can be displayed with high resolution.

  The height or depth of the convex portions and / or concave portions forming the diffraction grating is typically in the range of 0.1 μm to 1 μm. The grating constant of this diffraction grating is typically in the range of 0.5 μm to 2 μm.

  The convex portions and / or concave portions forming the light scattering structure are irregularly arranged in a region on the back surface of the light transmission layer 11. These convex portions and / or concave portions are formed, for example, so that the dimension in the direction parallel to the main surface of the light transmission layer 11 is 100 μm or less. If this dimension is reduced, the area can be reduced, and it becomes difficult to identify the configuration of the area, and an image can be displayed with high resolution. Moreover, the convex part and / or concave part which form the light-scattering structure are formed so that the dimension in a direction parallel to the main surface of the light transmission layer 11 is 0.1 μm or more, for example. When this dimension is reduced, a larger light scattering effect can be obtained.

  The height or depth of the convex portions and / or concave portions forming the light scattering structure is typically in the range of 0.1 μm to 10 μm. Further, the center-to-center distance between these convex portions and / or concave portions is typically in the range of 0.1 μm to 10 μm.

  The light transmission layer 11 may have a single layer structure or a multilayer structure. When the multilayer structure is employed for the light transmission layer 11, for example, a material having excellent strength can be used for the outermost layer, and a material suitable for pattern formation can be used for the innermost layer.

  As a material of the light transmission layer 11, for example, a resin having light transmittance can be used. For example, when a thermoplastic resin or a photocurable resin is used, the light transmission layer 11 having a plurality of convex portions and / or concave portions provided on one main surface can be easily formed by transfer using an original plate. .

The light transmission layer 11 can be formed by the following method, for example.
First, a resin film or sheet having light transparency is prepared. As a material of this resin film or sheet, for example, polyethylene terephthalate, polyvinyl chloride, polyester, polycarbonate, polymethyl methacrylate, polystyrene, or triacetyl cellulose can be used. Next, a photocurable resin layer such as an ultraviolet curable resin layer is formed on one main surface of the resin film or sheet, and an original is pressed against the photocurable resin layer. In this state, for example, the photocurable resin layer is irradiated with light such as ultraviolet rays through a resin film or sheet to be cured. Thereafter, the original plate is removed from the photocurable resin layer to obtain the light transmission layer 11.

  Alternatively, a thermoplastic resin layer is formed on one main surface of the previous resin film or sheet, and the original plate is pressed against the thermoplastic resin layer while applying heat. Thereby, the concave structure and / or convex structure formed in the original plate are transferred to the thermoplastic resin layer. Thereafter, the light-transmitting layer 11 is obtained by removing the original from the thermoplastic resin layer. In addition, when the resin film or sheet is thermoplastic, the original plate may be pressed while heat is applied thereto, and the concave structure and / or the convex structure formed on the original plate may be transferred to the resin film or sheet.

  The light transmission layer 11 may contain a coloring material such as a dye. For example, a multilayer structure may be adopted for the light transmission layer 11 and one layer thereof may contain a coloring material. In this case, the visual effect described later can be made more complicated by the combination of the light absorption characteristics of the coloring material and the light interference effect due to the structure of the reflective layer 12.

  The light transmission layer 11 can be omitted. However, if the light transmission layer 11 is provided, damage to the reflective layer 12 can be suppressed. Further, when the light transmission layer 11 is provided and the front surface thereof is a flat surface, it is difficult to duplicate the concave structure and / or the convex structure provided in the reflective layer 12. The thickness of the light transmission layer 11 is typically in the range of 1 μm to 50 μm. The light transmission layer 11 can play the same role as a dielectric layer 12b described later.

  The reflection layer 12 covers the main surface of the light transmission layer 11 where the convex portions and / or concave portions are provided. Typically, the reflective layer 12 has a multilayer structure in which a plurality of dielectric layers are stacked.

  When the reflective layer 12 has a multilayer structure formed by laminating a plurality of dielectric layers, the reflective layer 12 has a higher refractive index than a dielectric layer made of a high refractive material and a high refractive index material. It is a laminate with a dielectric layer made of a small low refractive material. When the reflective layer 12 includes three or more dielectric layers, typically, dielectric layers made of a high refractive material and dielectric layers made of a low refractive material are alternately stacked.

  Each dielectric layer included in the reflective layer 12 is light transmissive. When the reflective layer 12 has a multilayer structure, the layer forming the back surface of the reflective layer 12 may not be a dielectric layer. That is, a metal layer may be used instead of the dielectric layer. As a material for the metal layer, for example, aluminum, silver, or an alloy thereof can be used.

  At least one of the dielectric layers included in the reflective layer 12 includes first and second portions that are adjacent to each other in the in-plane direction and have different thicknesses.

  In the example shown in FIG. 2, the reflective layer 12 is composed of a laminate of dielectric layers 12a to 12c. In this example, the dielectric layer 12b includes first and second portions. As an example, in FIG. 1, it is assumed that regions R1, R3, and R5 correspond to the first portion, and regions R2 and R4 correspond to the second portion.

The dielectric layer 12 a covers the back surface of the light transmission layer 11. The refractive index of light having a wavelength λ ₁ in the visible light wavelength region is different between the dielectric layer 12 a and the light transmission layer 11. The dielectric layer 12a has a substantially uniform thickness. On the back surface of the dielectric layer 12a, a plurality of convex portions and / or concave portions are provided corresponding to the plurality of convex portions and / or concave portions provided on the back surface of the light transmission layer 11.

The dielectric layer 12b covers the back surface of the dielectric layer 12a. The refractive index for the previous wavelength λ ₁ differs between the dielectric layer 12b and the dielectric layer 12a. The front surface of the dielectric layer 12b is provided with a plurality of concave portions and / or convex portions corresponding to the plurality of convex portions and / or concave portions provided on the back surface of the dielectric layer 12a. The back surface of the dielectric layer 12b is, for example, a flat surface. As described above, the dielectric layer 12b includes first and second portions that are adjacent to each other in the in-plane direction and have different thicknesses. The front surface of each of the first and second portions includes a plurality of concave portions and / or convex portions.

The dielectric layer 12c covers the back surface of the dielectric layer 12b. The refractive index for the previous wavelength λ ₁ is different between the dielectric layer 12c and the dielectric layer 12b.

As the material of the dielectric layers 12a to 12c, for example, ceramics can be used. A material having a refractive index greater than 1.5 for light having a wavelength of 500 nm is a high refractive index material, and a material having a refractive index of 1.5 or less for this light is a low refractive index material. Examples thereof include ZnS, TiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , ZrO ₂ , CeO ₂ , HfO ₂ , Y ₂ O ₃ , and PbF ₂ . In this case, examples of the low refractive material include Na ₃ AlF ₆ , Na ₅ Al ₃ F ₁₄ , AlF ₃ , MgF ₂ , SiO ₂ , and BaF ₂ .

  The dielectric layers 12a to 12c can be formed by, for example, a vacuum deposition method, a sputtering method, or a coating method. Vapor deposition methods such as vacuum deposition and sputtering are suitable for forming a layer having a concave structure and / or a convex structure similar to those of the base. Further, according to the vapor deposition method, the film thickness can be controlled with high accuracy. On the other hand, the coating method is suitable for forming a layer having a flat surface. When the dielectric layer 12b is formed by the vapor deposition method, the thickness can be made different between the first portion and the second portion by using, for example, a mask.

  The display body 10 can further include a member other than the light transmission layer 11 and the reflection layer 12. For example, an adhesive layer may be formed on the back surface of the reflective layer 12.

Next, the visual effect brought about by the previous diffraction grating will be described.
FIG. 3 is a diagram schematically showing how the relief type diffraction grating emits diffracted light. In FIG. 3, 31 indicates illumination light, 32 indicates regular reflection light or zero-order diffracted light, and 33 indicates first-order diffracted light.

  When the diffraction grating is illuminated, the diffraction grating emits strong diffracted light in a specific direction with respect to the traveling direction of the illumination light 31 that is incident light.

The most representative diffracted light is the first-order diffracted light 33. The emission angle β of the first-order diffracted light 33 can be calculated from the following equation (1) when the light travels in a plane perpendicular to the lattice lines.
d = λ / (sin α−sin β) (1)
In this equation (1), d represents the grating constant of the diffraction grating, and λ represents the wavelengths of the incident light 31 and the diffracted lights 32 and 33. Α represents the exit angle of the 0th-order diffracted light 32, that is, transmitted light or specularly reflected light. In other words, the absolute value of α is equal to the incident angle of the illumination light 31 and is symmetric with respect to the normal line of the diffraction grating. For α and β, the clockwise direction from the Z axis is the positive direction.

  As is clear from equation (1), the exit angle β of the first-order diffracted light 33 varies with the wavelength λ. That is, the diffraction grating has a function as a spectroscope. Therefore, when the illumination light 31 is white light, changing the observation angle in a plane perpendicular to the grating line of the diffraction grating changes the color perceived by the observer.

In addition, the color perceived by the observer under a certain observation condition changes according to the lattice constant d.
As an example, it is assumed that the diffraction grating emits the first-order diffracted light 33 in the normal direction. That is, the emission angle β of the first-order diffracted light 33 is assumed to be 0 °. Assume that the observer perceives the first-order diffracted light 33. If the exit angle of the 0th-order diffracted light 32 at this time is α _N , equation (1) can be simplified to equation (2) below.

d = λ / sin α _N (2)
As is clear from equation (2), in order for the observer to perceive a specific color, the wavelength λ corresponding to the color, the incident angle | α _N | of the illumination light 31, and the lattice constant d are What is necessary is just to set so that the relationship shown to equation (2) may be satisfied. For example, white light including all light components having a wavelength in the range of 400 nm to 700 nm is used as the illumination light 31, and the incident angle | α _N | of the illumination light 31 is set to 45 °. It is assumed that a diffraction grating having a spatial frequency (reciprocal of the grating constant) distributed within a range of 1000 lines / mm to 1800 lines / mm is used. In this case, when the diffraction grating is observed from the normal direction, a portion having a spatial frequency of about 1600 lines / mm looks blue and a portion having a spatial frequency of about 1100 lines / mm looks red.

  Note that the diffraction grating is easier to form when the spatial frequency is smaller. Therefore, in a normal display body, the majority of diffraction gratings are diffraction gratings having a spatial frequency of 500 lines / mm to 1600 lines / mm.

  As described above, the color perceived by the observer under a certain observation condition can be controlled by the grating constant d (or spatial frequency) of the diffraction grating. When the observation angle is changed from the previous observation condition, the color perceived by the observer changes.

  In the above description, it is assumed that light travels in a plane perpendicular to the grid lines. When the diffraction grating is rotated around the normal line from this state, the effective value of the grating constant d changes according to the rotation angle with respect to a certain observation direction. As a result, the color perceived by the observer changes. In other words, when a plurality of diffraction gratings having only different grating line orientations are arranged, different colors can be displayed on the diffraction gratings. Further, when the rotation angle becomes sufficiently large, the diffracted light cannot be recognized from a certain observation direction and looks the same as when there is no diffraction grating.

  Further, when the depth of the grooves constituting the diffraction grating is increased, the diffraction efficiency changes (depending on the wavelength of illumination light, etc.). When the area ratio of the diffraction grating to the unit region, for example, the area ratio of the diffraction grating to the pixel described later, is increased, the intensity of the diffracted light is increased.

  Therefore, for example, if the spatial frequencies and / or orientations of the grooves are made different between the regions R1 to R5, different colors can be displayed in the regions R1 to R5, or the direction in which the light can be seen can be changed. For example, when at least one of the depth of the groove and / or the area ratio of the diffraction grating to the unit region is made different between the regions R1 to R5, the luminance of the regions R1 to R5 can be made different. Therefore, by using these, it is possible to display images such as full-color images and stereoscopic images.

  The “image” here means an image that can be observed as a spatial distribution of color and / or luminance. The “image” includes a photograph, a figure, a picture, a character, a symbol, and the like.

  In the display body 10, the dielectric layer 12b includes first and second portions that are adjacent to each other in the in-plane direction and have different thicknesses. In the example of FIGS. 1 and 2, the regions R1, R3, and R5 correspond to the first portion, and the regions R2 and R4 correspond to the second portion.

The thickness of the first portion is set so as to generate constructive interference when light having a wavelength λ ₁ in the visible light wavelength range is repeatedly reflected between one main surface and the other main surface. . For example, when n ₁ is a positive integer, the optical thickness D _{1 of} the first portion and the wavelength λ ₁ satisfy the relationship represented by the equation: D ₁ = n ₁ × λ _1/2 . .

The optical thickness D ₁ of the first part is the product of the thickness of the first part and the refractive index of light having the wavelength λ ₁ . As shown in FIG. 4, the thickness d ₁ of the first portion is provided with recesses only on one main surface of the first portion, and the width of these recesses is narrower than the interval between the recesses, When the main surface is a flat surface, it means the thickness of the first portion other than the recess. Further, as shown in FIG. 5, the convex portions are provided only on one main surface of the first portion, the width of the convex portions is narrower than the interval between the convex portions, and the other main surface is a flat surface. In this case, the thickness d ₁ of the first portion means the thickness of the portion other than the convex portion in the first portion. Further, the concave portion and / or the convex portion are provided only on one main surface of the first portion, the width of the concave portion and / or the convex portion is equal to the interval between the concave portion and / or the convex portion, and the other main surface is flat. In the case of a surface, the thickness d ₁ of the first portion means an average of the longest distance and the shortest distance in the thickness direction between the main surfaces. And as shown in FIG. 8, when the recessed part and / or convex part are provided in both surfaces of the 1st part, thickness d1 of a _1st part is the recessed part provided in one main surface. It means the distance from the bottom to the top of the convex portion provided on the other main surface correspondingly.

Further, the optical thickness D ₂ of the second part described later is the product of the thickness of the second part and the refractive index of the light having the wavelength λ ₁ . As shown in FIG. 4, the thickness d ₂ of the second part is provided with recesses only on one main surface of the second part, and the width of these recesses is narrower than the interval between the recesses, When the main surface is a flat surface, it means the thickness of the second portion other than the recess. Further, as shown in FIG. 5, the convex portions are provided only on one main surface of the second portion, the width of these convex portions is narrower than the interval between the convex portions, and the other main surface is a flat surface. In this case, the thickness d ₂ of the second portion means the thickness of the portion other than the convex portion in the second portion. Further, a concave portion and / or a convex portion are provided only on one main surface of the second portion, the width of the concave portion and / or the convex portion is equal to the interval between the concave portion and / or the convex portion, and the other main surface is flat. In the case of a surface, the thickness d ₂ of the second portion means an average of the longest distance and the shortest distance in the thickness direction between the main surfaces. And as shown in FIG. 8, when the recessed part and / or convex part are provided in both surfaces of the 2nd part, the thickness d2 of a _2nd part is the recessed part provided in one main surface. It means the distance from the bottom to the top of the convex portion provided on the other main surface correspondingly.

When this structure is adopted, the intensity of light of wavelength λ ₁ emitted from the regions R1, R3, and R5 is increased as compared with the case where the thickness of the first portion is not set as described above. That is, in the regions R1, R3, and R5, the color corresponding to the wavelength λ ₁ is emphasized.

Therefore, for example, when the observation angle is changed in a plane perpendicular to the grating line of the diffraction grating while keeping the incident angle of the illumination light constant, the regions R1, R3, and R5 have the wavelength λ at a certain angle. _It looks bright with a color corresponding to ₁ . Such a visual effect facilitates confirmation that the labeled article formed by attaching the display body 10 to the article is genuine.

  Also, this visual effect is difficult to achieve with other configurations. Moreover, the structure of the dielectric layer 12b including the first and second portions having different thicknesses from each other and having the above-described concave portion and / or convex portion provided on one main surface is accurately analyzed from the completed display body 10. It is difficult to do. And even if the previous structure can be analyzed from the completed display body 10, forgery or imitation of the display body including this structure is difficult. Therefore, when this display body 10 is used as a label for preventing forgery, a high forgery preventing effect can be realized.

The thickness of the second portion can be set so that destructive interference occurs when light having the wavelength λ ₁ is repeatedly reflected between one main surface and the other main surface. For example, when the n ₂ and a positive integer, and the optical thickness D ₂ of the second portion and the wavelength lambda ₁ is the equation: the D ₂ = (2n ₂ -1) relationship shown in × λ _1/4 You may set the thickness of a 2nd part so that it may satisfy.

Thus, the color corresponding to the wavelength λ ₁ can be weakened in the regions R2 and R4. That is, for example, if the observation angle is changed in a plane perpendicular to the grating line of the diffraction grating while the incident angle of the illumination light is kept constant, the wavelength R ₁ and the wavelength R ₁ in the regions R2 and R4 are observed at any angle. It becomes difficult to perceive the corresponding color. Therefore, when this configuration is adopted, a more complicated visual effect can be obtained.

The thickness of the second portion causes constructive interference when light having a wavelength λ ₁ within a visible light wavelength region different from the wavelength λ ₂ is repeatedly reflected between one main surface and the other main surface. You may set as follows. For example, the n ₃ is taken as a positive integer, and the optical thickness D ₂ and wavelength lambda ₂ of the second portion equation: so as to satisfy the relationship shown by D ₂ = n ₃ × lambda _2/2 You may set the thickness of a 2nd part.

When this structure is adopted, the intensity of the light having the wavelength λ ₂ emitted from the regions R2 and R4 is increased as compared with the case where the thickness of the second portion is not set as described above. That is, in the regions R2 and R4, the color corresponding to the wavelength λ ₂ is emphasized.

Therefore, for example, when the observation angle is changed in a plane perpendicular to the grating line of the diffraction grating while keeping the incident angle of the illumination light constant, the regions R2 and R4 are set to the wavelength λ ₂ at a certain specific angle. It looks bright with the corresponding color. That is, different colors can be emphasized in the regions R1, R3, and R5 and the regions R2 and R4.

When this configuration is adopted, the thickness of the first portion is set so as to cause destructive interference when light having the wavelength λ ₂ is repeatedly reflected between one main surface and the other main surface. be able to. For example, when the n ₄ and a positive integer, and the optical thickness D ₁ and wavelength lambda ₂ of the first portion equality: the D ₂ = (2n ₄ -1) relationship shown by × λ _2/4 You may set the thickness of a 1st part so that it may satisfy.

Thus, the color corresponding to the wavelength λ ₂ can be weakened in the regions R1, R3, and R5. That is, for example, if the observation angle is changed in a plane perpendicular to the grating line of the diffraction grating while keeping the incident angle of the illumination light constant, the wavelength λ in the regions R1, R3, and R5 is observed at any angle. _It becomes difficult to perceive the color corresponding to ₂ . Therefore, when this configuration is adopted, a more complicated visual effect can be obtained.

In the display body 10, the thickness of the dielectric layer 12a is such that, for example, a constructive interference occurs when light having the wavelength λ ₁ is repeatedly reflected between one main surface and the other main surface. Can be set. Alternatively, the thickness of the dielectric layer 12a can be set so as to generate constructive interference when light having the wavelength λ ₂ is repeatedly reflected between one main surface and the other main surface. Alternatively, the thickness of the dielectric layer 12a is such that light having a wavelength λ ₃ in the visible wavelength range different from the wavelengths λ ₁ and λ ₂ is repeatedly reflected between the one main surface and the other main surface. Can be set to produce constructive interference.

In addition, the thickness of the dielectric layer 12c can be set so as to generate constructive interference when light having the wavelength λ ₁ is repeatedly reflected between one main surface and the other main surface, for example. it can. Alternatively, the thickness of the dielectric layer 12c can be set so as to generate constructive interference when light having the wavelength λ ₂ is repeatedly reflected between one main surface and the other main surface. Alternatively, the thickness of the dielectric layer 12c is such that light having a wavelength λ ₄ in a visible light wavelength region different from the wavelengths λ ₁ and λ ₂ is repeatedly reflected between one main surface and the other main surface. Can be set to produce constructive interference.

  As described above, in this display body 10, the thickness of each of the dielectric layers 12a to 12c is such that when light having a predetermined wavelength is incident at a predetermined incident angle, one main surface and the other main surface Are set so as to generate constructive interference by repeatedly reflecting between the two. Thereby, the wavelength dependence of the reflected light intensity profile according to the observation direction occurs, and the interference color specific to the structure of the reflective layer 12 can be observed.

  In addition, when a large number of dielectric layers made of a high refractive material and dielectric layers made of a low refractive material are alternately laminated, the wavelength selectivity, that is, the narrowness of the wavelength band where the reflected light intensity is large, is further improved, Reflected light of a specific wavelength with higher degree and brightness can be obtained.

  The image displayed on the display 10 is advantageously composed of a plurality of pixels arranged two-dimensionally. This will be described below.

FIG. 6 is a plan view schematically showing an example of a method for forming a display surface with a plurality of pixels.
In the display body 10, a display surface is constituted by a plurality of pixels PX1 to PX7 arranged in a matrix. The diffraction gratings included in the pixels PX1 to PX3 and the diffraction gratings included in the PX5 to PX7 have similar lattice constants and are different only in the direction. Of the dielectric layer 12b, a part corresponding to a part of the pixels PX1 to PX3 and PX5 to PX7 is a first part, and a part corresponding to the other part of the pixels PX1 to PX3 and PX5 to PX7 is a second part. It is. Further, the pixel PX4 is not provided with a diffraction grating.

  That is, in the display body 10 shown in FIG. 6, an image is formed by seven types of pixels. If the visual effects of each of these seven types of pixels are known, it is easy to predict the image obtained by rearranging them. Therefore, the structure to be adopted for each pixel can be easily determined from the digital image data. Therefore, if the image to be displayed on the display body 10 is composed of a plurality of pixels arranged two-dimensionally, the display body 10 can be easily designed.

  In the display body 10 shown in FIG. 6, an image is formed by seven types of pixels, but the number of pixels forming the image may be two or more. However, more complex images can be displayed when the number of types of pixels is increased.

  Further, the number of pixels constituting the image may be two or more. However, when the number of pixels is increased, a higher definition image can be displayed.

  Each dimension of the pixels PX1 to PX3 and PX5 to PX7 is, for example, 300 μm or less. When the size of each pixel is small, it is impossible to identify each pixel when the display surface is observed with the naked eye.

  In the display 10 shown in FIG. 6, the diffraction gratings of the pixels PX1 to PX3 and PX5 to PX7 differ only in the orientation, but their structures may be different. That is, at least one of the spatial frequency, orientation, and depth of the grooves forming the diffraction grating, and the area ratio of the diffraction grating to the pixel may be made different from each other.

The display body 10 described above can be variously modified.
7 to 10 are sectional views schematically showing modifications of the display body shown in FIGS.

  The display body 10 shown in FIG. 7 has the same structure as the display body 10 shown in FIGS. 1 and 2 except that the dielectric layers 12a and 12c are omitted and the adhesive layer 15 is provided on the back surface of the reflective layer 12. have. In other words, in the display body 10, the reflective layer 12 is composed only of the dielectric layer 12b. The light transmission layer 11 and the adhesive layer 15 are different in refractive index from the dielectric layer 12b.

  When this structure is adopted, the effect described above with respect to the light interference in the reflective layer 12, that is, the wavelength selectivity of the dielectric multilayer film is small as compared with the case where the structure shown in FIG. 2 is adopted. However, the structure of the display body 10 is simplified compared to the display body 10 shown in FIG. Therefore, the display body 10 is easier to manufacture than the display body 10 shown in FIG.

  The display body 10 shown in FIG. 8 has a plurality of recesses on the back surface of the dielectric layer 12b and the front surface and back surface of the dielectric layer 12c corresponding to the plurality of recesses and / or protrusions provided on the back surface of the light transmission layer 11. And / or it has a structure similar to the display body 10 shown in FIG.1 and FIG.2 except having provided the convex part and providing the contact bonding layer 15 on the back surface of the reflection layer 12. FIG.

  When this structure is adopted, the number of interfaces provided with a plurality of concave portions and / or convex portions is increased as compared with the case where the structure shown in FIG. 2 is adopted. Therefore, for example, when a plurality of concave portions and / or convex portions forms a diffraction grating, the adoption of the structure shown in FIG. 8 improves the diffraction efficiency compared to the case where the structure shown in FIG. 2 is adopted. . Therefore, a clearer image can be displayed. In addition, when this structure is adopted, the phenomenon of changing to a rainbow color like a general hologram is remarkably suppressed. Therefore, if this structure is adopted, authenticity determination becomes easy.

  When this structure is employed, the adhesive layer 15 may employ a multilayer structure. For example, the back surface of the dielectric layer 12c is covered with a first adhesive layer as a flattening layer, and then a second adhesive layer having superior adhesive strength compared to the first adhesive layer is formed on the first adhesive layer. May be.

  The display body 10 shown in FIG. 9 has the same structure as the display body 10 shown in FIGS. 1 and 2 except that the dielectric layer 12c is omitted and the adhesive layer 15 is provided on the back surface of the reflective layer 12. doing. The adhesive layer 15 has a refractive index different from that of the dielectric layer 12b.

  When this structure is adopted, the effect described above with respect to the light interference in the reflective layer 12, that is, the wavelength selectivity of the dielectric multilayer film is small as compared with the case where the structure shown in FIG. 2 is adopted. However, the structure of the display body 10 is simplified compared to the display body 10 shown in FIG. Therefore, the display body 10 is easier to manufacture than the display body 10 shown in FIG.

  The display body 10 shown in FIG. 10 has the same structure as the display body 10 shown in FIGS. 1 and 2 except that the light absorption layer 16 and the adhesive layer 15 are laminated in this order on the back surface of the reflective layer 12. Have. The light absorption layer 16 is typically a black colored layer that exhibits low reflectance over the entire visible light wavelength range, but is a colored layer that exhibits low reflectance only in a part of the visible light wavelength range. May be.

  When this structure is employed, the intensity of reflected or transmitted light from the lower side of the reflective layer 12 is reduced in at least part of the visible light wavelength region, compared with the case where the structure shown in FIG. 2 is employed. Therefore, it becomes easy to confirm the visual effect due to the wavelength selectivity of the reflective layer 12.

  Instead of providing the light absorption layer 16, the adhesive layer 15 may contain coloring materials such as dyes and pigments. In this case, the same effect as described above can be obtained.

  In the example described above, the reflective layer 12 is composed of three or less dielectric layers, but the reflective layer 12 may be composed of more dielectric layers. Increasing the number of stacked dielectric layers increases the wavelength selectivity of the reflective layer 12. For example, the difference between the intensity of light that strengthens due to interference at the reflection layer 12 and the intensity of light that weakens due to interference at the reflection layer 12 increases. As a result, the visual effect described above becomes more prominent.

  In the above example, a relief-type diffraction grating is mainly formed by a plurality of convex portions and / or concave portions provided on the back surface of the light transmission layer 11, but these convex portions and / or concave portions are relief-type light scattering properties. A structure may be formed. Alternatively, a relief type diffraction grating may be formed by a part of a plurality of convex portions and / or concave portions, and a relief type light scattering structure may be formed by another portion.

  Unlike the above-described diffraction grating, the light-scattering structure has a small wavelength dependency of the light intensity profile according to the observation direction, and has the effect of spreading light over a wide angle range. Therefore, when the convex part and / or the concave part form a light-scattering structure, the image can be easily seen as compared with the case where the convex part and / or the concave part forms a diffraction grating. In addition, since the direction and angle range for spreading light can be set according to the size and shape of the convex and / or concave portions, the image formed by the light scattering structure becomes a whitish image, but has excellent visibility and visual effects. Can be realized.

  As described above, the dielectric layer 12b of the reflective layer 12 is different in thickness from the first part that causes constructive interference when light of a specific wavelength incident at a specific incident angle is repeatedly reflected. 2 parts. Therefore, in the first part, only the color corresponding to the previous wavelength is observed, or this color is emphasized and observed. On the other hand, in the second part, for example, it looks dark or looks different from the previous color. When the observation angle is changed while keeping the incident angle of the illumination light constant, the first and second portions change in color different from each other. For example, when the display 10 is observed from the front, yellow and blue are observed in the first and second parts, respectively, and when the display 10 is observed from the diagonal, red and green are observed in the first and second parts, respectively. Can be done. That is, the reflective layer 12 has a very characteristic visual effect.

  In addition, when a plurality of convex portions and / or concave portions form a diffraction grating, the effect of repeated reflection interference in the reflective layer 12 and the diffraction effect by the diffraction grating are combined to amplify the previous visual effect. . On the other hand, when a plurality of convex portions and / or concave portions form a light scattering structure, scattered light colored in a specific color can be obtained. Therefore, an extremely complicated visual effect can be obtained, and true / false determination is facilitated.

In addition, the visual effect resulting from the combination of the first and second portions having different thicknesses or a combination thereof with a plurality of convex portions and / or concave portions cannot be obtained only by duplicating the diffraction grating or the like using laser light. . Therefore, it is very difficult to forge or imitate the display body 10.
Therefore, the display body 10 achieves an extremely high forgery prevention effect.

  The display body 10 described above can be used, for example, as a forgery prevention or identification label. Since the display body 10 is difficult to counterfeit or imitate, when the label is supported on an article, it is also difficult to counterfeit or imitate the genuine article with the label. Moreover, since this label has the visual effect mentioned above, it is also easy to discriminate between an authentic product and a non-authentic product if it is unknown whether the product is genuine.

  FIG. 11 is a plan view schematically showing an example of a labeled article in which an anti-counterfeiting or identification label is supported on the article. FIG. 11 shows a printed matter 100 as an example of an article with a label.

  The printed material 100 is a magnetic card and includes a base material 51. The base material 51 is made of plastic, for example. A printed layer 52 and a strip-shaped magnetic recording layer 53 are formed on the substrate 51. Furthermore, the display body 10 mentioned above is affixed on the base material 51 as a forgery prevention or identification label.

  The printed material 100 includes a display body 10. Therefore, as described above, it is difficult to forge or imitate the printed material 100. In addition, since the printed matter 100 includes the display body 10, it is easy to discriminate between a genuine product and a non-authentic product for an article whose authenticity is unknown. In addition, since the printed matter 100 further includes the printed layer 52 in addition to the display body 10, it is easy to compare the appearance of the printed layer 52 with the appearance of the display body 10. Therefore, compared with the case where the printed matter 100 does not include the printed layer 52, it is easier to determine an article whose authenticity is unknown from a genuine product to a non-authentic product.

  In FIG. 11, a magnetic card is illustrated as a printed material including the display body 10, but the printed material including the display body 10 is not limited to this. For example, the printed matter including the display 10 may be another card such as a wireless card, an IC (integrated circuit) card, and an ID (identification) card. Alternatively, the printed matter including the display body 10 may be securities such as gift certificates and stock certificates. Alternatively, the printed matter including the display body 10 may be a tag to be attached to an article to be confirmed as a genuine product. Alternatively, the printed matter including the display body 10 may be a package body that contains an article to be confirmed to be genuine or a part thereof.

  Moreover, in the printed matter 100 shown in FIG. 11, the display body 10 is affixed on the base material 51, but the display body 10 can be supported on the base material by other methods. For example, when paper is used as the base material, the display body 10 may be rolled into the paper and the paper may be opened at a position corresponding to the display body 10.

  Moreover, the labeled article may not be a printed material. That is, the display body 10 may be supported on an article that does not include a printed layer.

The top view which shows schematically the display body which concerns on 1 aspect of this invention. Sectional drawing along the II-II line of the display body shown in FIG. The figure which shows a mode that a relief type diffraction grating inject | emits a diffracted light schematically. Sectional drawing which shows roughly an example of the dielectric material layer containing the 1st and 2nd part. Sectional drawing which shows schematically the other example of the dielectric material layer containing the 1st and 2nd part. The top view which shows roughly an example of the method of comprising a display surface with a some pixel. Sectional drawing which shows schematically the modification of the display body shown in FIG.1 and FIG.2. Sectional drawing which shows schematically the modification of the display body shown in FIG.1 and FIG.2. Sectional drawing which shows schematically the modification of the display body shown in FIG.1 and FIG.2. Sectional drawing which shows schematically the modification of the display body shown in FIG.1 and FIG.2. The top view which shows roughly an example of the labeled article formed by making an anti-counterfeiting or identification label supported by the article.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Display body, 11 ... Light transmission layer, 12 ... Reflection layer, 12a ... Dielectric layer, 12b ... Dielectric layer, 12c ... Dielectric layer, 15 ... Adhesion layer, 16 ... Light absorption layer, 31 ... Illumination light, 32: Regular reflection light or 0th order diffracted light, 33: First order diffracted light, 51: Base material, 52: Print layer, 53: Magnetic recording layer, 100: Printed matter.

Claims (10)

A reflective layer including a light transmissive first dielectric layer including first and second portions that are adjacent to each other in the in-plane direction and have different thicknesses, and the thickness of the first portion is one of the thicknesses; When the light having the wavelength λ ₁ in the visible light wavelength range is repeatedly reflected between the principal surface and the other principal surface, the constructive interference is generated, and the thickness of the second portion is set to one of the principal surfaces. The first dielectric is set so as to generate constructive interference when light having a wavelength λ ₂ in a visible wavelength range different from the wavelength λ ₁ is repeatedly reflected between the surface and the other principal surface. one main surface of the body layer comprises a first and a second region corresponding to said first and second portions, said first and second regions corresponding to the difference in thickness of the first and second portions to different heights, the recesses each plurality of throughout its the first and second regions and Or convex portions are provided, wherein the plurality of recesses and / or projections in each of the first and second regions displaying body characterized by forming a diffraction grating or light scattering structures. Wherein said plurality of recesses and / or projections in each of the first and second regions forms a diffraction grating child, diffraction gratings of the plurality of recesses and / or projections in the first region is formed The diffraction grating formed by the plurality of concave portions and / or convex portions in the second region is different from each other in at least one of a spatial frequency, an azimuth, and a depth of the groove. The display body according to 1.   3. The display body according to claim 1, wherein the main surface of the first dielectric layer provided with the plurality of concave portions and / or convex portions is formed by arranging a plurality of pixels in a matrix. . The thickness of the second portion is set so as to cause destructive interference when light having the wavelength λ ₁ is repeatedly reflected between one main surface and the other main surface. The display body according to any one of claims 1 to 3. When n ₁ and n ₂ are positive integers, the optical thickness D _{1 of} the first portion and the wavelength λ ₁ satisfy the relationship represented by the equation: D ₁ = n ₁ × λ _1/2. and, wherein the optical thickness D ₂ of the second portion and the wavelength lambda ₁ equation: characterized in that it satisfies the relationship represented by _{D 2 = (2n 2 -1)} × λ 1/4 The display body according to any one of claims 1 to 3. When the n ₃ and n ₄ and a positive integer, the optical thickness D ₁ of the first portion and the wavelength lambda ₂ is the equation: D ₁ = In _{(2n 3 -1) × λ 2} /4 satisfy the relationship indicated, the second portion of the optical thickness D ₂ and the wavelength lambda ₁ and the _{equation: D 2 = (2n 4 -1} ) that satisfies the relationship indicated by × λ _1/4 The display body according to claim 1, wherein: The reflective layer is adjacent to the first dielectric layer on the main surface side where the plurality of concave portions and / or convex portions are provided, and has a uniform thickness. The first dielectric layer has the wavelength The display body according to claim 1 , further comprising a second dielectric layer having a different refractive index with respect to λ ₁ . The main surface of the second dielectric layer away from the first dielectric layer has a plurality of recesses and / or protrusions provided on the main surface of the first dielectric layer. The display body according to claim 7 , wherein a concave portion and / or a convex portion are provided. The display body according to claim 1 , further comprising a light absorption layer facing the reflection layer. A printed matter comprising: a base material; a printed layer formed on the base material; and the display body according to claim 1 supported by the base material.

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