JP2016080848A - Display body and article with display body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display body changing in color depending on an observation direction when it is observed.SOLUTION: A display body comprises, on one principal surface of a light transmission layer 11, a plurality of rugged structure regions 12 formed having a parallel portion parallel to the light transmission layer 11 and a slope portion making an angle of 90° or less with the light transmission layer 11 and, on a top face thereof, a reflective layer 13 and an adhesive layer 15 laminated in this order. The display body has a pitch in the rugged structure regions 12 of the resolution of human eyes or less and diffraction light cannot be identified. An area ratio between the parallel portion and the slope portion of the rugged structure regions 12 when viewed from a vertical direction of the light transmission layer is different for each of the rugged structure regions 12.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image display body that is used for prevention of forgery and the like and whose appearance changes depending on observation conditions.

  Display with a visual effect different from that of ordinary printed materials for the purpose of preventing counterfeiting of securities such as gift certificates and checks, cards such as credit cards, cash cards, ID cards, and certificates such as passports and licenses Is applied in the form of a transfer foil, a sticker, or the like to a surface of a certificate such as securities or a card. Also, the distribution of counterfeit goods has become a social problem for articles other than securities and certificates, and there are increasing opportunities to apply similar anti-counterfeiting techniques to such articles.

  Examples of anti-counterfeiting technologies include micro characters, special light-emitting ink, watermarks, diffraction gratings, and holograms. This forgery prevention technology can be roughly divided into two. One is a counterfeit measure that determines authenticity by using a verification device such as a simple device or measurement device, and the other is a counterfeit measure that can be easily determined by the naked eye.

  As anti-counterfeiting technologies, various fine structures are produced by an electron beam drawing apparatus (EB apparatus), and security devices that can be visually differentiated from similar techniques have been developed. As a most general security device, there is a surface relief type diffraction grating (for example, Patent Document 1). A diffraction grating has a complicated structure as compared with a general printed matter, and it is difficult to produce the diffraction grating without a high fine processing technique.

Japanese Patent No. 2003-295744

However, recently, those exhibiting optical effects similar to those of diffraction gratings have been distributed, and the anti-counterfeiting effect of diffraction gratings has faded. Therefore, it is desired to provide a security device with new anti-counterfeiting properties excellent in anti-counterfeiting properties that replaces the diffraction grating.
In view of the above, an object of the present invention is to provide an image display body whose color changes depending on the observation direction when the image is observed.

  The invention according to claim 1 for achieving the above object includes, on one main surface of the light transmission layer, a parallel portion parallel to the light transmission layer and a slope portion forming an angle of 90 ° or less with the light transmission layer. A display body in which a plurality of concavo-convex structure regions are formed and a reflective layer and an adhesive layer are laminated in this order on the upper surface, and the pitch of the concavo-convex structure regions is below the resolution of the human eye, and diffracted light cannot be recognized The display is characterized by this.

  According to the second aspect of the present invention, on one main surface of the light transmission layer, the parallel portion parallel to the light transmission layer and the inclined surface forming an angle of 90 ° or less with the light transmission layer are orthogonal to the light transmission layer. A display body in which a plurality of concavo-convex structure regions composed of sloped surfaces are formed, and a reflective layer and an adhesive layer are laminated in this order on the upper surface, and the pitch of the concavo-convex structure regions is less than the resolution of the human eye and is diffracted The display is characterized by the fact that light cannot be recognized.

  The invention according to claim 3 is characterized in that the area ratio between the parallel portion and the slope portion of the concavo-convex structure as viewed from the vertical direction of the light transmission layer is different for each concavo-convex structure region. The display body according to Item 2 is obtained.

  The invention according to claim 4 is the display body according to claim 3, wherein the area ratio is set corresponding to the density of an image prepared in advance.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the convex portion or the concave portion of the concavo-convex structure is composed of a plane parallel to the light transmission layer and four planes. Or a display according to item 1.

  The invention according to claim 6 is the display body according to any one of claims 1 to 5, wherein the thickness of the reflective layer is different for each uneven structure region. is there.

  The invention according to claim 7 is the display body according to any one of claims 1 to 6, wherein a refractive index of the reflective layer is different for each of the uneven structure regions. is there.

  The invention according to claim 8 is an article with a display body, to which the display body according to any one of claims 1 to 7 is attached.

According to the invention of claim 1,
The concavo-convex structure of the display body includes a parallel portion parallel to the light transmission layer and a slope portion having an angle with the light transmission layer. Therefore, when the light is incident on the light transmission layer from the perpendicular direction and observed from the same direction, the incident angle of the light to the parallel part and the slope part is different, so different colors are displayed on the parallel part and the slope part due to thin film interference. The Moreover, a different color can be displayed on the slope portion by changing the angle of the slope portion. Furthermore, since the center-to-center distance of the concavo-convex structure is less than the resolution of the human eye, the colors displayed on the parallel part and the slope part are perceived as color mixing by juxtaposition additive color mixing. Further, when light is incident on the slope portion from the direction perpendicular to the light transmission layer and the display body is observed from the slope portion direction, only the interference light from the slope portion is observed, so that the color changes.

According to the invention of claim 2,
The uneven structure of the display body includes a parallel portion parallel to the light transmission layer, a slope portion having an angle with the light transmission layer, and a perpendicular portion in the perpendicular direction to the light transmission layer. Therefore, when light is incident on the slope portion from the direction perpendicular to the light transmission layer and the display body is rotated, reflected light cannot be confirmed at the perpendicular portion, but reflected light can be confirmed at the slope portion. Therefore, different colors can be expressed. That is, it is possible to switch images by rotating the display body.

According to the invention of claim 3,
When the concavo-convex structure region is observed from the perpendicular direction of the light transmission layer, the area ratio is different for each concavo-convex structure region. The color can be controlled by this area ratio.

According to the invention of claim 4,
The design can be improved by creating the area ratio corresponding to the shade of the image prepared in advance.

According to the invention of claim 5,
The convex or concave portion of the concavo-convex structure is composed of a plane parallel to the light transmission layer and four planes. Thereby, since the number of slope portions or perpendicular portions is limited, it is possible to easily determine image switching when the display body is rotated.

According to the invention of claim 6,
The thickness of the reflective layer provided in the concavo-convex structure is different for each concavo-convex structure region. Thereby, interference colors differ. Therefore, the interference colors that can be expressed can be increased.

According to the invention of claim 7,
The refractive index of the reflective layer provided in the concavo-convex structure is different for each concavo-convex structure region. Thereby, interference colors differ. Therefore, the interference colors that can be expressed can be increased.

According to the invention of claim 8,
By attaching the display body to the base material via the adhesive layer, it is possible to easily provide an article with improved security.

The figure of the top view explaining the schematic structure of the display body which becomes this invention. It is a figure of the cross sectional view which shows typically the structure of the cross section of II of the display body shown in FIG. It is the figure of the expanded sectional view which shows typically the structure of the uneven structure area | region A of the display body shown in FIG. It is the figure of the expanded sectional view which shows typically the structure of the uneven structure area | region B of the display body shown in FIG. It is the perspective view which expanded and showed an example of the structure employable for the uneven | corrugated structure area | region of the display body shown in FIG. It is the perspective view which expanded and showed an example of the structure employable for the uneven | corrugated structure area | region of the display body shown in FIG. It is the perspective view which showed the uneven structure of the general diffraction grating. The reflected light when light is incident on the concavo-convex structure from the perpendicular direction of the light transmission layer is shown. The reflected light when light is incident on the inclined surface of the concavo-convex structure from the perpendicular direction of the light transmission layer is shown. FIG. 8 is a cross-sectional view schematically showing how the diffraction grating of FIG. 7 emits diffracted light. It is sectional drawing which showed thin film interference. It is a figure of the upper surface view which shows a mode that the upper surface part area of the uneven structure was increased. It is a figure of the top view which shows typically a mode that the upper surface part area of the uneven structure was reduced. It is the perspective view which showed a mode that illumination light entered into the display body and observed. It is the perspective view which showed a mode that the display body of FIG. 14 rotated 90 degree | times, and made it observe by making illumination light enter into a display body. It is a figure of the top view which shows roughly an example of the card | curd which makes the article support the stripe transfer foil for forgery prevention. It is sectional drawing along the II-II line of the display body 40 of FIG.

(Embodiment)
Hereinafter, the display body of the present invention will be described with reference to the drawings.
FIG. 1 is a top plan view showing one embodiment of the display body of the present invention. FIG. 2 is a cross-sectional view taken along the line II of FIG. The display body 10 includes at least a light transmission layer 11, a reflection layer 13, and an adhesive layer 15. In the example shown in FIG. 2, the light transmission layer 11 side is the front side (observer side), and the adhesive layer 15 side is the back side.

The interface between the light transmission layer 11 and the reflective layer 13 includes a first uneven structure region 12a, a second uneven structure region 12b, a third uneven structure region 12c, and a flat region 12e provided with a plurality of uneven structures. . The adhesive layer 15 is formed on the reflective layer 13.

  The light transmissive layer 11 protects the concavo-convex structure from dirt and scratches on the surface, thereby achieving the effect of maintaining the visual effect of the display body 10 over a long period of time. Furthermore, the light transmission layer 11 makes the reproduction difficult by not exposing the uneven structure.

  As a constituent material of the light transmission layer 11, for example, a resin having light transmittance can be used. Examples of the resin having optical transparency include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, nitrocellulose, polyethylene, polypropylene, acrylic styrene copolymer, vinyl chloride, and polymethyl methacrylate. Thermosetting resins such as polyimide, polyamide, polyester urethane, acrylic urethane, epoxy urethane, silicone, epoxy, melamine resin, etc., and various acrylic monomers, epoxy acrylate, urethane acrylate that are UV or electron beam curable Reactive polymers such as oligomers such as polyester acrylate, acrylics and epoxies with acrylic and methacrylic groups, and cellulosic resins are used. Possible it is.

  The light transmission layer 11 may have a structure of two or more layers in consideration of surface strength, easiness of forming a concavo-convex structure, and the like. Further, when a metal is used as the constituent material of the reflective layer 13, in order to change the metallic luster color derived therefrom to a different color, a dye or pigment is mixed into the light transmission layer 11, and a specific wavelength is set for the dye or pigment. It is also possible to absorb the light.

  The reflective layer 13 plays a role of increasing the reflectance of the interface provided with the concavo-convex structure. As a constituent material of this reflective layer 13, metal materials, such as aluminum, silver, tin, chromium, nickel, copper, gold | metal | money, and those alloys, can be used, for example. The reflective layer 13 may be made of a material having a refractive index different from that of the constituent material of the light transmission layer 11 such as a dielectric material. The reflective layer 13 is not limited to a single layer, and may be a multilayer. The reflective layer 13 can be formed by using a metal and an oxide such as titanium oxide or zinc sulfide and utilizing a vacuum film forming method. As the vacuum film forming method, a vacuum deposition method, a sputtering method, or the like can be applied.

  The thickness of the reflective layer is 200 nm or less. ZnS (zinc oxide) is used for the reflective layer of the display body 10, and a film thickness of 50 nm is provided. As a method of forming a different film thickness for each concavo-convex structure region, a mask is formed on the concavo-convex structure and vapor deposition is performed. By changing the mask position and repeating the deposition, different film thicknesses can be produced. Further, the method of forming a reflective layer having a different refractive index for each concavo-convex structure region is the same as described above.

  The adhesive layer 15 is provided in order to attach the display body 10 to an article for which anti-counterfeiting measures are desired. This adhesive layer 15 may have a structure of two or more layers in consideration of the adhesive strength between the display body 10 and the article to be counterfeited, the smoothness of the adhesive surface of the article, and the like. FIG. 2 shows a configuration in which the display body 10 is observed from the light transmission layer 11 side, but the display body 10 is observed from the reflective layer 13 side by providing an adhesive layer 15 on the opposite side of FIG. It is also possible to adopt a configuration that does this.

  Next, the concavo-convex structure provided at the interface between the light transmission layer 11 and the reflection layer 13 will be described. The first uneven structure region 12a, the second uneven structure region 12b, and the third uneven structure region 12c at the interface have uneven structures having different structures. Specifically, the first uneven structure region 12a has a one-dimensional diffraction grating structure, and the second uneven structure region 12b has a one-dimensional uneven structure in which diffracted light cannot be recognized. The third uneven structure region 12c has a two-dimensional uneven structure in which diffracted light cannot be recognized. The other interface portion exhibits a flat region 12e.

  FIG. 3 is an enlarged view of the region A of the second uneven structure region 12b of FIG. As shown in FIG. 3, the second concavo-convex structure region 12b is a lattice structure in which convex portions extend in the Y direction, and is regularly arranged in the X direction. Although not shown in FIG. 3, a reflective layer is laminated with a substantially uniform thickness on the concavo-convex structure. The concavo-convex structure includes an upper surface portion 14a and a lower surface portion 14b that are parallel to the light transmission layer, and a slope portion 14c. The slope portion 14c has an inclination angle of 45 degrees ± 1 degree with respect to the light transmission layer.

  In the above description, the inclination angle is approximately 45 degrees, but the effective range of the inclination angle is 1 to 90 degrees. The behavior of the reflected light with respect to the incident light perpendicular to the light transmission layer on the viewer side is different at each inclination angle. As an example, the height of the concavo-convex structure is 4 μm, the distance of the flat portion 14b of the concave portion is the same distance as the X component when the slope portion 14c is decomposed into the X component and the Z component, and incident light is incident on the center of the slope The behavior of light will be described. When the inclination angle is 1 to 40 degrees, the incident light is reflected and emitted by the inclined surface only once. When the inclination angle is 41 to 52 degrees, the light is reflected twice on the slope and emitted. When the inclination angle is 45 degrees, the light behavior of re-reflection is shown. In addition, when the inclination angle is 53 to 89 degrees, the light is reflected and emitted in the concavo-convex structure portion twice or more. When the tilt angle is 90 degrees, no reflection occurs. The inclination angle refers to an angle formed between the light transmission layer and the inclined surface.

  FIG. 4 is an enlarged view of a region B of the third uneven structure region 12c of FIG. As shown in FIG. 4, a plurality of convex portions are regularly arranged in the third concavo-convex structure region 12c. The concavo-convex structure shown in FIG. 4 includes an upper surface portion 15a, a lower surface portion 15b, and a slope portion 15c. The slope portion 15c has an inclination of approximately 30 degrees with respect to the light transmission layer. Although the convex portions are regularly arranged in FIG. 4, the convex portions may be randomly arranged as shown in FIG. In addition, as shown in FIG. 6, a part of the slope portion constituting the concavo-convex structure may be constituted by a perpendicular portion 16 d that is perpendicular to the light transmission layer 11. In FIG. 3 to FIG. 6, there is the concave flat portion 14 b between the convex portions, but it is not necessary to provide the concave flat portion 14 b leaving only the concave portion. Although not shown in FIGS. 4 to 6, the reflective layer is laminated with a substantially uniform thickness on the concavo-convex structure.

  Next, the uneven structure will be described in detail.

  As shown in FIG. 7, the first concavo-convex structure region 12a is provided with a diffraction grating in which a plurality of grooves 14a are arranged. The distance between the centers of the grooves 14a (hereinafter also referred to as pitch) is in the range of 500 nm to 2000 nm, for example. The depth of the groove 14a is, for example, in the range of 100 nm to 1000 nm, and typically in the range of 100 nm to 300 nm.

  The term “diffraction grating” means a structure that generates a diffracted wave when irradiated with illumination light such as natural light. In addition to a normal diffraction grating in which a plurality of grooves 14a are arranged in parallel and at equal intervals, the term “diffraction grating” is recorded on a hologram. The interference fringes made are also included. Further, the groove 14a or a portion sandwiched between the grooves 14a is referred to as a “lattice line”.

  As shown in FIG. 3, a plurality of convex portions 14 are provided in the second concavo-convex structure region 12b. These convex portions 14 are arranged with a larger center-to-center distance than the above-described center-to-center distance (pitch) of the groove 14a. The pitch of the convex part of a 2nd uneven structure exists in the range of 5 micrometers-145 micrometers. Moreover, the height of the convex part is 0.1 μm to 5 μm. The reason why the pitch is 5 μm to 145 μm is that when the display body at a position 500 mm away from the observer is observed, the resolution of the human eye with a visual acuity of 1.0 is generally 1 minute. Due to this limitation, a structure of 145 μm or less cannot be visually recognized. Therefore, when the pitch is 145 μm or less, the adjacently arranged lines cannot be separated and visually recognized. Therefore, a display body that displays a high-quality image can be provided by setting the pitch to 145 μm or less. Further, when the thickness is 5 μm or less, the diffraction angle becomes large and each wavelength can be identified. If the height of the convex portion is 0.1 μm or less, the structure is buried in the reflective layer, and a desired effect cannot be obtained. On the other hand, when the height is 5 μm or more, the aspect ratio becomes 1 or more, and molding becomes difficult. Therefore, the height is set to 5 μm or less.

  In the third uneven structure region 12c, the uneven structure as described above is arranged. Since the center-to-center distance and depth of the concavo-convex structure are in the same range as the above numerical values, they are omitted. The difference between the second uneven structure region 12b and the third uneven structure region 12c is whether the uneven structure is a one-dimensional array or a two-dimensional array.

Next, the behavior of light when light enters the concavo-convex structure will be described.
FIG. 8 shows the behavior of light when light is incident on the second concavo-convex structure region 12b from the perpendicular direction of the light transmission layer. At the upper surface portion 14a or the lower surface portion 14b, incident light is reflected according to the law of reflection. The slope 14c is incident and reflected at an incident angle of 45 degrees, and is incident on and reflected from the adjacent slope. FIG. 9 shows a trajectory of light that is incident on the slope 14c and is not re-reflected by the opposing slope 14c.

  Next, the visual effect resulting from the uneven structure of the first uneven structure region 12a will be described. FIG. 10 is a diagram schematically illustrating how the first concavo-convex structure region emits diffracted light. In FIG. 10, a locus 31a indicates illumination light, a locus 32a indicates specularly reflected light or 0th-order diffracted light, and a locus 33a indicates first-order diffracted light.

  The most representative diffracted light is first-order diffracted light. The emission angle β of the first-order diffracted light can be calculated from the following equation (1) when the light travels in a plane perpendicular to the grating line of the diffraction grating.

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 incident light and diffracted light. Α represents the exit angle of 0th-order diffracted light, 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, and the incident angle is symmetrical with respect to the Z axis (in the case of a reflective diffraction grating). For α and β, the clockwise direction from the Z axis is the positive direction.

  As is apparent from equation (1), the exit angle β of the first-order diffracted light changes according to the wavelength λ. That is, the diffraction grating has a function as a spectroscope. Accordingly, when the illumination light is white light, the color perceived by the observer changes when the observation angle is changed in a plane perpendicular to the grating line of the diffraction grating.

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

d = λ / sin αN (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 | αN | of the illumination light, and the lattice constant d are equal to each other. What is necessary is just to set so that the relationship shown in (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 illumination light, the incident angle | αN | of the illumination light is set to 45 °, and the spatial frequency (reciprocal of the lattice constant) is used. ) Is distributed in the range of 1000 lines / mm to 1800 lines / mm. 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 the spatial frequency is about 11
The area of 00 / 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.

  Next, the thin film interference of the second uneven structure region 12b and the third uneven structure region 12c will be described. The second concavo-convex structure region 12b and the third concavo-convex structure region 12c have an action similar to that of the interference film formed by the optical thin film 30 shown in FIG. 11, and reinforce and weaken a specific wavelength by repeating reflection and interference. Is possible. FIG. 11 shows a state in which a part of incident light 304 incident on the optical thin film 30 at an angle θ is reflected on the front and back surfaces of the optical thin film 30, reflected to the side where the light source 302 is present, and transmitted. ing.

  The light reflected from the optical thin film 30 is superimposed on the light emitted to the light source side after being reflected an odd number of times within the optical thin film 30. When each light has no phase difference, the maximum reflected light is obtained, and the difference in optical distance at that time is an integral multiple of the wavelength, and the following expression (3) is established.

mλ = 2 × TO × cos θ (3)
Here, m is the order and TO is the optical distance. TO takes into account the refractive index of the medium through which light propagates in addition to the physical distance. When the film thickness of the optical thin film 30 is D and the refractive index is n, TO = nD is established. At this time, since interference that cancels out at other wavelengths occurs, it becomes impossible to recognize other than a specific wavelength. This means that the wavelength of light reflected on the light source side surface can be controlled by controlling the optical distance of the thin film.

  As shown in FIG. 8, a case where light is incident on the upper surface portion or the lower surface portion, that is, a case where the incident angle is 0 degree is considered. Then, Equation (3) can derive an intensifying interference equation like Equation (4).

mλ = 2 × TO (4)
Further, consider the case where light is incident on the slope portion 14c of FIG. 9, that is, the incident angle is 45 degrees. Then, Equation (3) can derive an intensifying interference equation like Equation (5).

mλ = √2 × TO (5)
As shown above, the wavelength that reinforces changes as the incident angle changes. This means that the reflected wavelength can be controlled by changing the inclination of the concavo-convex structure.

  Moreover, it turns out that the wavelength which reinforces also changes with optical distance TO so that Formula (3) may show. Therefore, the perceived wavelength can also be controlled by changing the refractive index n of the thin film or the film thickness D of the optical thin film 30.

  From the above, the light incident on the second concavo-convex structure region 12b can observe different colors between the upper surface portion 14a or the lower surface portion 14b and the inclined surface portion 14c. In addition, since the upper surface portion, the lower surface portion, and the slope portion are all less than the resolution of the human eye, each color cannot be perceived, and the colors of the upper surface portion, the lower surface portion, and the slope portion are changed by juxtaposed additive color mixing. Perceived as a mixed color.

That is, the perceivable color can be changed by changing the area ratio between the area of the upper surface portion 14a and the lower surface portion 14b and the area of the slope portion 14c. The area ratio corresponds to the shade of the image prepared in advance. The shading is expressed by a gray scale of 256 gradations, and the area ratio between the upper surface portion and the lower surface portion of the concavo-convex structure region is 1 to 100%. The design is performed by arranging the number of gradations on the image so that the area ratio corresponds to the gradation. That is, when the number of gradations is 1 in the image, the area ratio between the upper surface portion and the lower surface portion is 1%, and when the number of gradations is 50, the area ratio between the upper surface portion and the lower surface portion is 50%. is there.

  FIG. 12 shows a case where the area of the upper surface portion 16a is increased. The white-painted portion in FIG. 12 represents the slope portion 16b. In this case, the wavelength strengthened at the upper surface portion 16a is more dominant than the wavelength strengthened at the slope portion. Therefore, as for the perceived color, the strengthened wavelength is strongly observed on the upper surface.

  FIG. 13 shows a case where the area of the upper surface portion 16a is reduced. A white portion in FIG. 13 represents the slope portion 16b. In this case, the wavelength strengthened at the slope portion is more dominant than the wavelength strengthened at the upper surface portion. Therefore, the perceived color is strongly observed at the strengthened wavelength at the slope.

  When the light reflected by the slope portion is observed as shown in FIG. 9, only the wavelength strengthened by the slope portion is observed. That is, the perceived color is different between the case where the display body is observed from the perpendicular direction of the light transmission layer and the case where the light reflected only from the slope portion is observed. Therefore, the perceived color can be changed by changing the observation position, and a highly secure display body can be manufactured.

  FIG. 14 is a diagram showing a result of irradiating the white light source 302 from the normal direction of the light transmission layer of the display body and observing from the normal direction of the light transmission layer. The diffracted light from the first uneven structure region 12a cannot be observed. In the second concavo-convex structure regions 12b and 12c, an interference color due to thin film interference can be observed.

  FIG. 15 shows a result obtained by rotating the display body of FIG. 14 by 90 degrees on the XY plane, causing the white light source 302 to enter from the perpendicular direction of the light transmission layer, and observing the display body from the intermediate direction between the Y-axis direction and the Z-axis direction. . Since the concavo-convex structure region 12a is observed from a direction parallel to the lattice direction, diffracted light cannot be observed. Further, since the uneven structure region 12b is also observed from a direction parallel to the lattice direction, the reflected light cannot be observed. In the concavo-convex structure region 12c, as shown in FIG. 4, since the concavo-convex structure is two-dimensionally arranged, the reflected light can be confirmed. Therefore, under such conditions, it is possible to perceive the interference color only in the uneven structure region 12c.

  That is, this display body is constituted by a concavo-convex structure region 12a that shines in rainbow color by diffracted light, a concavo-convex structure region 12b that changes color when rotated on the XY plane, and a concavo-convex structure region 12c that changes color even when rotated on the XY plane. The By combining such regions, a display body with high security can be manufactured.

  FIG. 16 is a plan view schematically showing an example of a card 40 in which an anti-counterfeit stripe transfer foil is supported on an article.

  The card 40 includes a plastic substrate 44, and a printed layer 41 is formed on the plastic substrate 44. Further, the display body 43 is affixed to the card 40 as a forgery-preventing stripe transfer foil. The display body 43 has a region 46a where a one-dimensional relief type diffraction grating is formed, a plurality of grooves coarser than the region 46a, an average center-to-center distance of 10 μm, a concavo-convex structure depth of 2 μm, and a groove 1 The uneven structure region 46b and the flat region 46c are dimensionally arranged.

17 is a cross-sectional view taken along the line II-II of the display shown in FIG. This display body 43
Is a laminate in which a surface protective layer / peeling layer 42, a light-transmitting emboss layer 49, a reflective layer 48, an adhesive layer 45, and a plastic substrate 44 are laminated. In the example shown in FIG. 17, the surface protective layer / peeling layer 42 side is the front side and the plastic substrate 44 side is the back side. The interface between the light transmitting embossed layer 49 and the reflective layer 48 includes the uneven structure region 46b and the flat region 46c. The reflective layer is made of ZnS and has a thickness of 50 nm and is provided uniformly in the concavo-convex structure.

  The card 40 includes a display body 43. Therefore, when the white light source is irradiated from the perpendicular direction of the card 40 and the reflected light is observed from the vicinity of the perpendicular direction of the card 40, the region 46b can confirm a pale interference color. Further, the visible color changes to white by tilting the observation position in the X-axis direction. Furthermore, if the card 40 is rotated 90 degrees in this observation position, the interference color cannot be visually recognized. The printed layer 41 has no visible color change even when the observation position or the light source position is changed.

  Thus, unlike the print layer 41, the region 46b can change its color by changing the observation position. Therefore, since the authenticity can be determined by the color change, the forgery prevention effect is high.

DESCRIPTION OF SYMBOLS 10 ... Display body 11 ... Light transmission layer 12 ... Uneven structure area 13 ... Reflective layer 15 ... Adhesive layer 41 ... Printing part 14 ... Uneven structure part 30 ... Optical thin film 302 ... Light source 303 ... Observer 304 ... Incident light 305 ... Reflected light 306 ... Transmitted light

Claims (8)

  On one main surface of the light transmissive layer, a plurality of concavo-convex structure regions including a parallel portion parallel to the light transmissive layer and a slope portion having an angle of 90 ° or less with the light transmissive layer are formed. A display body in which the adhesive layer is laminated in this order, and the pitch of the concavo-convex structure region is below the resolution of the human eye, and the diffracted light cannot be recognized.   A plurality of concavo-convex structure regions comprising a parallel portion parallel to the light transmission layer, a slope portion forming an angle of 90 ° or less with the light transmission layer, and a slope portion orthogonal to the light transmission layer on one main surface of the light transmission layer A display body in which a reflective layer and an adhesive layer are laminated in this order on the upper surface thereof, wherein the pitch of the concavo-convex structure region is less than the resolution of the human eye and diffracted light cannot be recognized .   The display body according to claim 1, wherein an area ratio between the parallel portion and the slope portion of the concavo-convex structure viewed from the vertical direction of the light transmission layer is different for each concavo-convex structure region.   The display body according to claim 3, wherein the area ratio is set corresponding to the density of an image prepared in advance.   The display body according to any one of claims 1 to 4, wherein the convex portion or the concave portion of the concavo-convex structure includes a plane parallel to the light transmission layer and four planes.   The display body according to any one of claims 1 to 5, wherein the thickness of the reflective layer is different for each uneven structure region.   The display body according to claim 1, wherein the refractive index of the reflective layer is different for each of the uneven structure regions.   An article with a display body, to which the display body according to any one of claims 1 to 7 is attached.

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