Copy-protection media

Abstract

To enable discrimination between an original and a duplication by observation with the naked eye under excitation light irradiation.SOLUTION: In a duplication prevention medium, a light-transmitting base material includes a first face and a second face which is a face on an opposite side of the first face. The light-transmitting base material has an ultraviolet absorbing property. The first face includes a plurality of first colored parts and first non-colored parts arranged in an alternating manner. The second face includes a plurality of second colored parts and second non-colored parts arranged in the alternating manner. The first colored part reflects a first reflected light, and the second colored part reflects a second colored light. The first colored part includes a first colored layer containing first color pigment and a first fluorescent pigment that develops color by an excitation light. The second colored part includes a second colored layer containing a second color pigment of a color different from the first colored part, and a second fluorescent pigment.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a copy-protected medium. [Background technology]

[0002] With the recent improvement in the performance of color copiers, it has become easier to counterfeit securities such as stock certificates and bonds, as well as various certificates. For this reason, copy-protection media that make it possible to distinguish these items from copies are sometimes used for these items.

[0003] A copy-protected medium is a recording medium to which anti-counterfeiting technology is applied in order to prevent or deter counterfeiting using a color copier, etc. For example, a copy-protected medium may display specific characters, pictures, or other patterns that are not found on the original on a copy obtained using a color copier.

[0004] As one of the counterfeit prevention technologies for copy-protected media, an image formation method has been proposed in which, for example, three types of fluorescent inks containing fluorescent pigments that emit R (red), G (green), and B (blue) light are used to print RGB image data corresponding to an image on the substrate of the copy-protected media, forming a fluorescent image on the substrate; the fluorescent image is invisible under white light, but when irradiated with excitation light, it emits RGB light, and a fluorescent image corresponding to the image is visible through additive color mixing (see Patent Document 1).

[0005] Another proposed copy prevention medium has an image formed on the substrate of the copy prevention medium, the image including a first phosphor that emits a first color with a first afterglow time when irradiated with excitation light, and a second phosphor that emits a second color with a second afterglow time that is longer than the first afterglow time (see Patent Document 2).

[0006] Printed matter on such copy-protected media exhibits a two-stage color change, consisting of a mixture of the first and second colors and the second color, but it is difficult to ensure security in the light emitted from the image with only a two-stage color change on one surface of the substrate. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 10-35089 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-67043 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made taking these points into consideration, and aims to provide a highly secure copy-prevention medium that allows an observer to visually recognize three different color changes: the color of the image visible under white light, the color of the image on one side visible under irradiation with excitation light, and the color of the image on the other side, which is the back side, and enables the original to be distinguished from a copy by observation with the naked eye. [Means for solving the problem]

[0009] A copy prevention medium for solving the above problem includes a light-transmitting substrate having a first surface and a second surface opposite to the first surface, the light-transmitting substrate having ultraviolet absorbing properties, the first surface includes a plurality of first colored portions and a plurality of first non-colored portions arranged alternately; the second surface includes a plurality of second colored portions and a plurality of second non-colored portions arranged alternately; The copy prevention medium has a width of the first non-colored portion and the second non-colored portion within a range of 5 μm to 100 μm.

[0010] The first colored portion reflects first colored light, the second colored portion reflects second colored light, the first colored portion has a first colored layer containing a first colored pigment and a first fluorescent pigment that changes color in response to excitation light, and the second colored portion has a second colored layer containing a second colored pigment of a different color from the first colored pigment and a second fluorescent pigment of a different color from the second fluorescent pigment.

[0011] This is a copy prevention medium characterized in that the second colored portion is arranged to face the first non-colored portion through a light-transmitting substrate, and the second non-colored portion is arranged to face the first colored portion through a light-transmitting substrate.

[0012] When the image area of ​​the authenticity discrimination section of the above-mentioned copy-protection medium is observed under white light, the observer sees a mixed color of the first colored section and the second colored section through the transparent substrate in the original and the copy made by a color copier, and the original and its copy cannot be distinguished by observation with the naked eye.

[0013] Therefore, when the image area of ​​the authenticity discriminating section in the above-mentioned copy prevention medium is observed by the reflected light of the first colored portion on the first surface under irradiation with excitation light, the observer sees only the color of the fluorescent colored light of the first colored portion. This is because the original is observed through a light-transmitting substrate that has ultraviolet absorption properties, so the observer does not see the reflected light of the second colored portion on the second surface, and sees only the color of the fluorescent colored light of the first colored portion, not a mixed color.

[0014] Similarly, when the image area of ​​the authenticity discrimination section in the above-mentioned copy-protection medium is observed using the reflected light of the second colored section on the second surface under irradiation with excitation light, the observer only sees the color of the fluorescent colored light of the second colored section, and is not affected by color mixing caused by the reflected light of the first colored section on the first surface.

[0015] Since the first fluorescent pigment in the first colored portion and the second fluorescent pigment in the second colored portion are different in color, the color observed from the first surface and the color observed from the second surface when the original in the copy-protection medium is irradiated with excitation light are also different.

[0016] On the other hand, copies made by a color copier are made through a light-transmitting substrate that does not absorb ultraviolet light, and when observed from the first and second sides under irradiation with excitation light, they are affected by color mixing due to reflected light from the opposite sides. When comparing the original and the copy, the color difference observed from the first side is visible, making it possible to distinguish between the original and the copy by observation with the naked eye. Similarly, when observed from the second side, the color difference visible between the original and the copy makes them distinguishable by observation with the naked eye.

[0017] As described above, the original copy of the above-mentioned copy-protection medium and its copy can be distinguished by observing with the naked eye by comparing the color of the image visible under white light, and the color of the image on one side visible under irradiation with excitation light with the color of the image on the other side, which is the back side.

[0018] The width of the first and second non-colored portions is preferably in the range of 5 μm to 100 μm, where a width smaller than 5 μm is difficult to manufacture, and a width larger than 100 μm makes it difficult for an observer to recognize the color of an image visible under white light as an image of mixed colors, thereby failing to fully achieve the effects of the present invention.

[0019] According to yet another aspect of the copy prevention medium for solving the above problems, the widths of the first non-colored portions and the second non-colored portions may be equal or different. The first non-colored portions may be arranged regularly or irregularly. Similarly, the second non-colored portions may be arranged regularly or irregularly.

[0020] According to yet another aspect of the copy prevention medium that solves the above problem, there is provided a copy prevention medium relating to any of the above aspects, in which the second colored portion and the second non-colored portion face the first non-colored portion and the first colored portion, respectively, via a light-transmitting substrate.

[0021] When this configuration is adopted, in the observation image visible when viewed from the first side of the copy prevention medium, at least a part of the second colored portion is visible at the position of the first non-colored portion. Also, in the observation image visible when viewed from the second side of the copy prevention medium, at least a part of the first colored portion is visible at the position of the second non-colored portion. Therefore, when the copy prevention medium is viewed from the first or second side, the above-mentioned effect is more reliably achieved.

[0022] According to still another aspect of the copy prevention medium for solving the above-mentioned problems, a width of the first non-colored portion is smaller than a width of the second non-colored portion facing the first non-colored portion via a light-transmitting substrate, In the copy prevention medium according to the above aspect, the width of the second non-colored portion is smaller than the width of the first colored portion that faces the second non-colored portion via a light-transmitting substrate.

[0023] When this configuration is adopted, the above-mentioned effect can be obtained more reliably when the copy prevention medium is observed from the first or second surface.

[0024] According to yet another aspect of the copy prevention medium that solves the above problem, there is provided a copy prevention medium relating to any of the above aspects, in which the first colored portions and the first non-colored portions have linear shapes and are arranged alternately in the width direction, and the second colored portions and the second non-colored portions have linear shapes and are arranged alternately in the width direction.

[0025] In this copy prevention medium, the first colored portions, the first uncolored portions, the second colored portions, and the second uncolored portions may have linear shapes. Alternatively, the first colored portions, the first uncolored portions, the second colored portions, and the second uncolored portions may include portions having curved shapes. Alternatively, the first colored portions may form a nested arrangement pattern, and the second colored portions may form a nested arrangement pattern corresponding to the first colored portions.

[0026] In these cases, the widths of the first and second colored portions may be constant or may vary along the length of the line, and adjacent first colored portions may have the same or different widths.

[0027] The width of the first non-colored portion may be constant or may vary along the length of the line. Furthermore, the widths of the multiple first non-colored portions may be equal or different. Similarly, the width of the second non-colored portion may be constant or may vary along the length of the line. Furthermore, the widths of the multiple second non-colored portions may be equal or different.

[0028] Alternatively, according to yet another aspect of the copy prevention medium that solves the above problem, there is provided a copy prevention medium relating to any of the above aspects, in which the first colored portions and the first non-colored portions are arranged in a checkerboard pattern, and the second colored portions and the second non-colored portions are arranged in a checkerboard pattern.

[0029] The light-transmitting substrate has visible light transmittance. The light-transmitting substrate is preferably colorless, transparent, or colorless, translucent. For example, when illuminated with white light, the light-transmitting substrate transmits the incident light without coloring it. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a plan view schematically illustrating a copy protection medium according to an embodiment of the present invention; [Figure 2] FIG. 2 is an enlarged cross-sectional view of a portion of the copy prevention medium shown in FIG. 1. [Figure 3] 2 is an enlarged plan view of a portion of the first surface of the copy prevention medium shown in FIG. 1. FIG. [Figure 4] 4 is an enlarged plan view showing a part of the first surface shown in FIG. 3. [Figure 5] 2 is an enlarged plan view of a portion of the second surface of the copy prevention medium shown in FIG. 1. [Figure 6] FIG. 6 is an enlarged plan view of a portion of the back surface shown in FIG. 5. [Figure 7]2 is a diagram showing an example of an observation when the first surface of the copy prevention medium shown in FIG. 1 is illuminated with white light; FIG. [Figure 8] 8 is a diagram showing an image displayed by the copy-protection medium shown in FIG. 1 under the conditions of FIG. 7; [Figure 9] 2 is a diagram showing an example of an observation when the second surface of the copy prevention medium shown in FIG. 1 is illuminated with white light; FIG. [Figure 10] 10A and 10B are diagrams showing images displayed by the copy-protection medium shown in FIG. 1 under the conditions shown in FIG. 9; [Figure 11] FIG. [Figure 12] 2 is a diagram schematically illustrating an example of observation when the first surface of the copy prevention medium shown in FIG. 1 is illuminated with excitation light. [Figure 13] 13 is a diagram showing an image displayed by the copy-protection medium shown in FIG. 1 under the conditions of FIG. 12. [Figure 14] 2 is a diagram schematically illustrating an example of observation when the second surface of the copy prevention medium shown in FIG. 1 is illuminated with excitation light. [Figure 15] 15 is a diagram showing an image displayed by the copy-protection medium shown in FIG. 1 under the conditions of FIG. 14. [Figure 16] FIG. 10 is a plan view schematically showing an example of a structure that can be employed for a first colored layer of a copy prevention medium according to a first modified example. [Figure 17] FIG. 10 is a plan view schematically showing an example of a structure that can be employed for the second colored layer of the copy prevention medium according to the first modified example. [Figure 18] FIG. 10 is a plan view schematically showing an example of a structure that can be employed for the first colored layer of the copy prevention medium according to the second modified example. [Figure 19] FIG. 10 is a plan view schematically showing an example of a structure that can be employed for the second colored layer of the copy prevention medium according to the second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, embodiments will be described with reference to the drawings. The embodiments described below are more specific embodiments of any of the above aspects. Elements having the same or similar functions are designated by the same reference numerals, and redundant descriptions will be omitted.

[0032] FIG. 1 is a plan view schematically showing a copy prevention medium according to one embodiment of the present solution. FIG. 2 is a cross-sectional view showing an enlarged portion of the copy prevention medium shown in FIG. 1. FIG. 3 is a plan view showing an enlarged portion of the first side of the copy prevention medium shown in FIG. 1. FIG. 4 is a plan view showing an enlarged portion of the first side shown in FIG. 3. FIG. 5 is a plan view showing an enlarged portion of the second side of the copy prevention medium shown in FIG. 1. FIG. 6 is a plan view showing an enlarged portion of the second side shown in FIG. 5. In each figure, the X and Y directions are parallel to the display surface of the copy prevention medium 1 and are perpendicular to each other, and the Z direction is perpendicular to the X and Y directions, i.e., the thickness direction of the copy prevention medium 1.

[0033] The copy-protected medium 1 shown in Fig. 1 is a gift certificate. The copy-protected medium 1 may be a security other than a gift certificate. Alternatively, the copy-protected medium 1 may be a certificate such as an identity card or an identification card.

[0034] The copy prevention medium 1 includes a light-transmitting substrate 11, a first colored layer 12, and a second colored layer 13 shown in FIG. 2, and a printed layer 14 shown in FIG.

[0035] A polymer film can be used as the light-transmitting substrate 11. Suitable polymer films are those made of resins with high light transmittance, such as polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene (PE), and triacetyl cellulose (TAC). An appropriate material is selected for the light-transmitting substrate 11 depending on the application of the copy prevention medium. Here, as an example, the light-transmitting substrate 11 is assumed to be a colorless and transparent polymer film.

[0036] The light-transmitting substrate 11 has a rectangular shape with its long sides parallel to the X direction. The light-transmitting substrate 11 may have other shapes.

[0037] When the light-transmitting substrate 11 is a polymer film, the total light transmittance is preferably 87% or more and 93% or less. There is no upper limit to the total light transmittance, but considering the refractive index of the polymer film, it is difficult to produce a polymer film with a total light transmittance higher than 93%. Here, the "total light transmittance" is a value obtained by the method specified in JIS K7375:2008 "Plastics - Determination of total light transmittance and total light reflectance."

[0038] When the light-transmitting substrate 11 is a polymer film, the haze is preferably 4% or less. There is no lower limit for the haze, but it is usually 0.1% or more. Here, "haze" is a value obtained by the method specified in JIS K7136:2000 "Method for determining the haze of plastic transparent materials."

[0039] The light-transmitting substrate 11 also has ultraviolet absorbing properties. There are no particular limitations on the method for imparting ultraviolet absorbing properties, and methods that can be used include adding an ultraviolet absorber to the resin material of the light-transmitting substrate 11, impregnating the light-transmitting substrate 11 with a film, and coating the light-transmitting substrate 11 with a film.

[0040] Examples of a method for coating the formed light-transmitting substrate 11 include a method for coating a dispersion containing an ultraviolet absorber using a dip coater, die coater, slit coater, bar coater, gravure coater, or the like.

[0041] When forming the ultraviolet absorbing layer by coating, it is preferable to make the thickness of the ultraviolet absorbing layer thin. The thickness of the ultraviolet absorbing layer is preferably 0.01 μm or more and 1,000 μm or less, and more preferably 0.02 μm or more and 500 μm or less. If the thickness is less than 0.01 μm, the amount of ultraviolet absorption may be insufficient, and if it exceeds 1,000 μm, the transmittance of visible light may decrease. The content of the ultraviolet absorber in the ultraviolet absorbing layer varies depending on the ultraviolet absorber used and cannot be generally defined, but it is preferable to appropriately select a content that gives an ultraviolet transmittance that does not impair the effect of the present copy prevention medium.

[0042] The ultraviolet absorber is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, etc. These may be used alone or in combination of two or more.

[0043] Examples of commercially available light-transmitting substrates 11 having ultraviolet absorbing properties include ultraviolet absorbing PET films such as Tetron film manufactured by Teijin.

[0044] The light-transmitting substrate 11 has a first surface and a second surface opposite to the first surface. The first surface and the second surface correspond to the upper and lower surfaces of the light-transmitting substrate 11 in FIG.

[0045] The first colored layer 22 provided on the first surface of the light-transmitting substrate 11 is composed of a plurality of first colored portions 121 and first non-colored portions 122 arranged alternately on the first surface. The first colored portions 121 contain a first color pigment and a first fluorescent pigment. When illuminated with white light, the first colored pigment reflects the first colored light, and when illuminated with excitation light, the first fluorescent pigment reflects the first fluorescent colored light. When illuminated with white light from the first surface, the first non-colored portions 122 transmit the white light without coloring it, and when illuminated with excitation light, the ultraviolet absorption properties of the light-transmitting substrate 11 suppress transmission of the white light to the second surface. According to one example, the first non-colored portions 122 are spaces sandwiched between the first colored portions 121. According to another example, the first non-colored portions 122 are made of a colorless, transparent material that fills the gaps between the first colored portions 121.

[0046] The second colored layer 23 provided on the second surface of the light-transmitting substrate 11 includes a plurality of second colored portions 131 and second non-colored portions 132 arranged alternately on the second surface. The second colored portions 131 include a second color pigment of a different color from the first colored pigment and a second fluorescent pigment of a different color from the first fluorescent pigment. When illuminated with white light, the second colored pigment reflects the second colored light. When illuminated with excitation light, the second fluorescent pigment reflects second fluorescent colored light. When illuminated with white light from the second surface, the second non-colored portions 132 transmit the white light without coloring it. When illuminated with excitation light, the ultraviolet absorption properties of the light-transmitting substrate 11 suppress transmission of the white light to the first surface. According to one example, the second non-colored portions 132 are spaces sandwiched between the second colored portions 131. According to another example, the second non-colored portions 132 are made of a colorless, transparent material that fills the gaps between the second colored portions 131.

[0047] The thickness of the first colored portion 121 and the second colored portion 131 is preferably 0.3 μm or more. If the first colored portion 121 and the second colored portion 131 are less than 0.3 μm, the adhesion to the light-transmitting substrate 11 may be insufficient.

[0048] The first colored portion 121 and the second colored portion 131 can be formed by printing. For example, first, the first colored portion 121 is formed by printing on a first surface of the light-transmitting substrate 11. Next, after appropriate alignment, the second colored portion 131 is formed by printing on a second surface of the light-transmitting substrate 11. The printing order may start with the second colored portion 131. The printing method is appropriately selected from known printing methods such as screen printing, screen offset printing, gravure printing, gravure offset printing, flexographic printing, and reverse printing, depending on the dimensions and gaps of the first colored portion 121 and the second colored portion 131 to be formed.

[0049] The first colored portion 121 and the second colored portion 131, which are visible under white illumination, can contain a color pigment and a polymer. The color pigment can be an organic pigment, an inorganic pigment, or a combination thereof known in the art.

[0050] Inorganic pigments include metals, oxides such as titanium dioxide, zinc oxide, and iron oxide, hydroxides, sulfides, selenides, ferrocyanides, chromates, sulfates, carbonates, silicates, phosphates, and carbon. Organic pigments include carbon compounds, nitroso compounds, nitro compounds, azo compounds, lake pigments, phthalocyanine compounds, and condensed polycyclic materials.

[0051] The polymer is a colorless, transparent resin or a colored resin, such as a thermoplastic or thermosetting resin, including polycarbonate resin, acrylic resin, fluorine-based acrylic resin, silicon-based acrylic resin, epoxy acrylate resin, polystyrene resin, acrylonitrile-styrene resin, cycloolefin polymer, methylstyrene resin, fluorene resin, polyethylene terephthalate (PET), polypropylene, phenolic resin, melamine resin, polyethylene naphthalate (PEN), and polyimide (PI).

[0052] Examples of thermoplastic resins that can be used include polyethylene terephthalate (PET), polycarbonate (PC), polystyrene (PS), cyclic olefin copolymer (COC), acrylic resins such as polymethyl methacrylate (PMMA), cycloolefin polymer (COP), methacrylic acid-styrene copolymer (MS), acrylonitrile-styrene copolymer (AS), polyethylene naphthalate (PEN), and polyimide (PI). Examples of thermosetting resins that can be used include phenolic resin, melamine resin, epoxy resin, and alkyd resin, which are well known in the art.

[0053] Other resins that can be used include engineering plastics and super-engineering plastics such as polybutylene terephthalate (PBT), polyoxymethyl (POM), polyamide (PA), and polyphenyl sulfide (PPS).Other resins that can be used include resins that are cured by ionizing radiation, such as acrylic resins, urethane resins, epoxy resins, polyester resins, and thiol resins.

[0054] The first colored portion 121 and the second colored portion 131 may further include light scattering particles. The light scattering particles may be spherical or irregularly shaped. The material of the light scattering particles may be either organic or inorganic.

[0055] Examples of organic materials suitable for light-scattering particles include acrylic resins, polystyrene, styrene-acrylic copolymers or their crosslinked products, melamine-formaldehyde condensates, urethane resins, polyesters, silicone resins, fluorine particles, epoxy resins, and their copolymers. Examples of inorganic materials suitable for light-scattering particles include clay compounds such as smectite, kaolinite, and talc; inorganic oxides such as silica, titania, alumina, silica-alumina, zirconia, zinc oxide, barium oxide, and strontium oxide; inorganic carbonates such as calcium carbonate, barium carbonate, magnesium carbonate, and strontium carbonate; inorganic chlorides such as barium chloride and strontium chloride; inorganic sulfates such as barium sulfate and strontium sulfate; inorganic nitrates such as barium nitrate and strontium nitrate; inorganic hydroxides such as barium hydroxide, aluminum hydroxide, and strontium hydroxide; and glass.

[0056] The first colored portion 121 and the second colored portion 131, which are visible under ultraviolet light irradiation, emit fluorescent colors due to fluorescent pigments. Either inorganic or organic phosphors can be selected as the phosphor used for the fluorescent pigment depending on the color to be emitted. Examples of inorganic phosphors that emit red light include Y2O3:Eu, YVO4:Eu, 3.5MgO, 0.5mgF, 2GeO2:Mn, (Y,Gd)Bo3:Eu, and Y(P,V)O4:Eu. Examples of inorganic phosphors that emit green light include ZnO:Zn, Zn3SiO2:Mn, Zn3S:Cu,Al, (Zn,Cd)S:Cu,Al, ZnS:Cu,Au,Al, Zn2SiO4:Mn, ZnS:Ag,Cu, (Zn,Cd)S:Cu, ZnS:Cu, Gd2O2:Tb, La2O2S:Tb, Y2SiO5:Ce,Tb, Zn2GeO4:Mn, CeMgAl11O13:Tb, SrGa2S4:Eu2+, ZnS:Cu,CO, MgO·nB2O3:Ce,Tb, LaOBr:Tb,Tm, La2O2S:Tb, and ZnS:Cu(Mn). Examples of inorganic phosphors that emit blue light include ZnS:Ag, CaWO, YSiO:Ce, ZnS:Ag,Ga,Cl, CaBOCl:Eu, and BaMgAlO. 23 :Eu2+, Sr3(PO2)3Cl:Eu, etc.

[0057] On the other hand, examples of organic fluorescent materials include diaminostilbene disulfonic acid derivatives, imidazole derivatives, coumarin derivatives, derivatives of triazole, carbazole, pyridine, naphthalic acid, imidazolone, etc., dyes such as fluorescein and eosin, and compounds having a benzene ring such as anthracene.

[0058] The ink used to form the first colored portion 121 and the second colored portion 131 may further contain a solvent in addition to the above components. The solvent is, for example, dodecane or tetradecane. Other compounds or compositions may also be used as the solvent. For example, for quick-drying inks, solvents with low boiling points and volatilizing at room temperature, such as methyl ethyl ketone (MEK), ethanol, and acetone, may be used. For water-based inks, water (purified water) may be used as the solvent. For oil-based inks, oils that are difficult to volatilize at room temperature, such as aliphatic hydrocarbons, glycol ethers, and higher alcohols, may be used as the solvent.

[0059] The printed layer 14 is provided on the first surface of the light-transmitting substrate 11. The printed layer 14 displays, for example, characters, patterns, figures, photographs, or a combination thereof.

[0060] The printed layer 14 can be further provided on the second surface of the light-transmitting substrate 11. Alternatively, the printed layer 14 can be provided on the second surface instead of the first surface of the light-transmitting substrate 11. Alternatively, the printed layer 14 can be omitted.

[0061] 1, the print layer 14 has an opening, that is, a window W. The portion of the copy prevention medium 1 corresponding to the window W is an authenticity discrimination portion used to discriminate the authenticity of the copy prevention medium 1.

[0062] The first surface of the light-transmitting substrate 11 has a first printed area R1A and a first non-printed area R1B shown in Figures 2 and 3 at the position of the window W. On the other hand, the second surface has a second printed area R2A and a second non-printed area R2B shown in Figures 2 and 5 at the position of the window W.

[0063] Here, the first printed area R1A is formed of a first colored portion and a first non-colored portion, and is a pattern corresponding to the character string "COPY." The first non-printed area R1B is an area other than the first printed area R1A. Also, here, the second printed area R2A is a pattern corresponding to a mirror image of the character string "COPY," and the second non-printed area R2B is its reverse pattern.

[0064] The first colored layer 12 is provided on the first surface of the light-transmitting substrate 11 at the position of the window W. The first colored layer 12 is not provided on the first non-printing region R1B shown in Figures 2 and 3, but is provided on the first printing region R1A.

[0065] 2 and 4, the first colored layer 12 includes first colored portions 121 and first non-colored portions 122 arranged alternately on the first surface. The first colored portions 121 and first non-colored portions 122 each have a linear shape and are arranged alternately in the width direction. Here, the first colored portions 121 and first non-colored portions 122 each have a shape extending in the X direction and are arranged alternately in the Y direction.

[0066] The first colored portions 121 reflect first colored light when illuminated with white light. The first colored portions 121 are formed from ink containing a first color pigment, a first fluorescent pigment, and a polymer.

[0067] The width W1a of the first colored portion 121 is constant along the length direction of the first colored portion 121. Adjacent first colored portions 121 have the same width W1a. The width W1a is in the range of 5 μm to 100 μm.

[0068] When illuminated with white light, the first uncolored portions 122 transmit the white light without coloring it. Here, the first uncolored portions 122 are spaces between adjacent first colored portions 121.

[0069] The width W1b of the first uncolored portion 122 is constant along the length direction of the first uncolored portion 122. Furthermore, the widths W1b of adjacent first uncolored portions 122 are equal to each other.

[0070] The width W1b is in the range of 5 μm to 100 μm. Here, the width W1b is smaller than the width W1a. The sum of the width W1a and the width W1b is the pitch P1 of the arrangement of the first colored portions 121 or the first non-colored portions 122.

[0071] The second colored layer 13 is provided on the second surface of the light-transmitting substrate 11 at the position of the window W. The second colored layer 13 is not provided on the second non-printing region R2B shown in Figures 2 and 5, but is provided on the second printing region R2A.

[0072] As shown in FIGS. 2 and 6, the second colored layer 13 includes second colored portions 131 and second non-colored portions 132 arranged alternately on the second surface. The second colored portions 131 and second non-colored portions 132 are arranged alternately on the second surface corresponding to the first colored portions and first non-colored portions. The second colored portions 131 and second non-colored portions 132 each have a linear shape and are arranged alternately in the width direction. Here, the second colored portions 131 and second non-colored portions 132 each have a shape extending in the X direction and are arranged alternately in the Y direction.

[0073] The second colored portions 131 reflect second colored light when illuminated with white light. The second colored portions 131 are formed from ink containing a second color pigment having a color different from that of the first colored light, a second fluorescent pigment, and a polymer.

[0074] The width W2a of the second colored portion 131 is constant along the length direction of the second colored portion 131. Furthermore, the widths W2a of adjacent second colored portions 131 are equal to each other.

[0075] The width W2a is in the range of 5 μm to 100 μm, and is equal to the width W1a.

[0076] When illuminated with white light, the second uncolored portions 132 transmit the white light without coloring it. Here, the second uncolored portions 132 are spaces between adjacent second colored portions 131.

[0077] The width W2b of the second uncolored portion 132 is constant along the length direction of the second uncolored portion 132. Furthermore, the widths W2b of adjacent second uncolored portions 132 are equal to each other.

[0078] The width W2b is in the range of 5 μm to 100 μm. Here, the width W2b is smaller than the width W2a. Also, here, the width W2b is equal to the width W1b. The sum of the width W2a and the width W2b is the pitch P2 of the arrangement of the second colored portions 131 or the second non-colored portions 132.

[0079] 2, the second colored portions 131 face the first uncolored portions 122 with the light-transmitting substrate 11 interposed therebetween. The first colored portions 121 face the second uncolored portions 132 with the light-transmitting substrate 11 interposed therebetween. In an orthogonal projection onto a plane parallel to the first surface, the center line of each of the second colored portions 131 coincides with the center line of the first uncolored portion 122 facing the second colored portion 131. In addition, in this orthogonal projection, the center line of each of the first colored portions 121 coincides with the center line of the second uncolored portion 132 facing the first colored portion 121.

[0080] In this solution, the original copy prevention medium 1 and the copy 2 made by a color copier can be distinguished by naked eye. This will be explained below.

[0081] Fig. 7 is a diagram showing an example of a state in which a reflected image displayed by the copy prevention medium 1 shown in Fig. 1 is observed. Fig. 8 is a diagram showing an image displayed by the copy prevention medium 1 shown in Fig. 1 under the conditions shown in Fig. 7.

[0082] 7, the light source LS and the copy prevention medium 1 are positioned so that illumination light IL from the light source LS illuminates the first surface of the copy prevention medium 1 from an oblique direction, and the observer OB observes the reflected light RL emitted from the copy prevention medium 1. The illumination light IL is white light.

[0083] Under these conditions, the contribution of the second colored layer 13 to the display is smaller than the contribution of the first colored layer 12 to the display. That is, the contribution of the first colored light to the display is larger than the contribution of the second colored light to the display. Therefore, under these conditions, the color of the area corresponding to the character string "COPY" in the image I2 viewed by the observer OB is perceived as a mixed color closer to the color of the first colored light than to the color of the second colored light.

[0084] On the other hand, when the copy prevention medium 1 shown in Fig. 9 is observed from the second side, the contribution of the first colored layer 12 to the display is smaller than the contribution of the second colored layer 13 to the display. That is, the contribution of the second colored light to the display is larger than the contribution of the first colored light to the display. Therefore, under these conditions, the color of the area corresponding to the inverted character string "COPY" in the image I3 viewed by the observer OB shown in Fig. 10 is perceived as a mixed color closer to the color of the second colored light than to the color of the first colored light.

[0085] Under conditions in which the first colored portions 121 and the second non-colored portions 132, and the first non-colored portions 122 and the second colored portions 131 are printed in a 1:1 relationship, when observed from the first side, the contribution of the first colored layer 12 to the display is approximately the same as the contribution of the second colored layer 13 to the display, while when observed from the second side, the contribution of the second colored layer 13 to the display is approximately the same as the contribution of the first colored layer 12 to the display. Therefore, the color of the area corresponding to the string "COPY" in image I3 viewed by observer OB is perceived as a mixture of the same colors when observed from either side.

[0086] The color of the area corresponding to the string "COPY" in image I3 viewed by observer OB varies depending on the proportion of the first colored portion 121 and the second non-colored portion 132 and the image area formed by the first non-colored portion 122 and the second colored portion 131, and may be the same color or different colors when observed from the first side and the second side of the image area.

[0087] In contrast, when observing a copy 2 made by a color copier under the conditions shown in Figures 7 and 9, the color that is produced in the above-mentioned area is the result of subtractive color mixing of the color of the dot-shaped portion 221 and the color of the dot-shaped portion 231 shown in Figure 11, and therefore it is difficult for the naked eye to distinguish the original copy-protection medium 1 from the copy 2.

[0088] Fig. 12 is a diagram showing a state in which a reflected image displayed by the copy prevention medium 1 shown in Fig. 1 is observed under irradiation with excitation light. Fig. 13 is a diagram showing an image displayed by the copy prevention medium 1 shown in Fig. 1 under the conditions shown in Fig. 12.

[0089] In Figure 12, the light source LS' and the copy prevention medium 1 are positioned so that illumination light IL' from the excitation light source LS' illuminates the first surface of the copy prevention medium 1 from an oblique direction, and the observer OB observes the reflected light RL' emitted by the copy prevention medium 1.

[0090] Under these conditions, the second colored layer 13 contributes to the display via the light-transmitting substrate 11 to which the ultraviolet absorber has been added, and therefore does not contribute to the display of the first colored layer 12. Therefore, under these conditions, the color 15 of the area corresponding to the character string "COPY" in the image I2 viewed by the observer OB is only the colored light of the first fluorescent pigment.

[0091] In contrast, when a copy 2 containing the same fluorescent pigment as the present invention is copied using a color copier and observed under the same conditions as in Figure 12, the influence of the second colored layer 13 contributes to the display of the first colored layer 12 because the copy is made through a light-transmitting base material to which no ultraviolet absorber has been added. Therefore, under these conditions, the color of the area corresponding to the character string "COPY" in image I2 viewed by observer OB is colored light resulting from a mixture of the first and second fluorescent pigments.

[0092] Therefore, by visually recognizing this difference in color, the copy prevention medium 1 and the copy 2 can be distinguished from each other.

[0093] The same is true when the copy prevention medium 1 shown in Fig. 14 is observed from the second side with an excitation light source: the contribution of the first colored layer 12 to the display is via the light-transmitting substrate 11 to which the ultraviolet absorber has been added, and therefore ... of the second colored layer 13 is via the light-transmitting substrate 11 to which the ultraviolet absorber has been added. Therefore, as shown in Fig. 15, under these conditions, the color 16 of the area corresponding to the inverted character string "COPY" in the image I3 viewed by the observer OB is the colored light of the second fluorescent pigment only.

[0094] In contrast, when a copy 2 containing the same fluorescent pigment as the present invention is copied using a color copier and observed under the same conditions as in Figure 14, the influence of the first colored layer 12 contributes to the display of the second colored layer 13 because the copy is made through a light-transmitting base material to which no ultraviolet absorber has been added. Therefore, under these conditions, the color of the area corresponding to the inverted character string "COPY" in image I3 viewed by observer OB is colored light resulting from a mixture of the second fluorescent pigment and the first fluorescent pigment.

[0095] Therefore, by visually recognizing this difference in color, the copy prevention medium 1 and the copy 2 can be distinguished from each other regardless of which side they are viewed from.

[0096] The copy prevention medium 1 can be modified in various ways. For example, in the copy prevention medium 1 described above, the first colored portion 121, the first uncolored portion 122, the second colored portion 131, and the second uncolored portion 132 each have a linear shape, but they may also include portions having a curved shape. For example, the first colored portion 121, the first uncolored portion 122, the second colored portion 131, and the second uncolored portion 132 may each have a waveform such as a sine wave shape. Alternatively, the first colored portion 121, the first uncolored portion 122, the second colored portion 131, and the second uncolored portion 132 may have the following shapes:

[0097] Fig. 16 is a plan view schematically showing an example of a structure that can be employed for the first colored layer of the copy prevention medium 1 according to the first modified example. Fig. 17 is a plan view schematically showing an example of a structure that can be employed for the second colored layer of the copy prevention medium 1 according to the first modified example.

[0098] 16, the first colored portions 121 form a nested arrangement pattern. Specifically, the first colored portions 121 form a concentric pattern.

[0099] 17, the second colored portions 131 form a nested arrangement pattern corresponding to the first colored portions 121. Specifically, the second colored portions 131 form a concentric pattern such that the second colored portions 131 and the second non-colored portions 132 face the first non-colored portions 122 and the first colored portions 121, respectively.

[0100] A copy prevention medium similar to the copy prevention medium 1 described above, except for adopting such a configuration, also achieves the above-mentioned effects.

[0101] In the copy prevention medium 1, the first colored portions 121 and the first non-colored portions 122 each have a linear shape and are arranged alternately in the width direction, and the second colored portions 131 and the second non-colored portions 132 each have a linear shape and are arranged alternately in the width direction. The first colored portions 121, the first non-colored portions 122, the second colored portions 131, and the second non-colored portions 132 do not have to have a linear shape.

[0102] Fig. 18 is a plan view schematically showing an example of a structure that can be employed for the first colored layer of the copy prevention medium 1 according to the second modified example. Fig. 19 is a plan view schematically showing an example of a structure that can be employed for the second colored layer of the copy prevention medium 1 according to the second modified example.

[0103] 18, the first colored portions 121 and the first non-colored portions 122 are arranged in a checkerboard pattern. In Fig. 20, the second colored portions 131 and the second non-colored portions 132 are arranged in a checkerboard pattern. The second colored portions 131 and the second non-colored portions 132 face the first non-colored portions 122 and the first colored portions 121, respectively.

[0104] A copy prevention medium similar to the copy prevention medium 1 described above, except for adopting such a configuration, also achieves the above-mentioned effects. [Example]

[0105] Specific examples of the present invention will be described below.

[0106] <Manufacturing copy-protected media> Example 1 The copy prevention medium 1 described with reference to Figure 1 was produced by the following method, in which the printed layer 14 was omitted.

[0107] First, a Tetron film manufactured by Teijin was prepared as the light-transmitting substrate 11. Next, a first colored layer 12 was formed on a first surface of the light-transmitting substrate 11 by gravure offset printing using an ink obtained by mixing a commercially available cyan process ink with a fluorescent pigment that emits blue (B). The width W1a of the first colored portion 121 and the width W1b of the first non-colored portion 122 were each set to 20 μm.

[0108] Thereafter, a second colored layer 13 was formed on the second surface of the light-transmitting substrate 11 by gravure offset printing using an ink made by mixing a commercially available magenta process ink with a fluorescent pigment that emits red (R). The width W2a of the second colored portion 131 and the width W2b of the second non-colored portion 132 were each 20 μm. The second colored layer 13 was formed so that, in orthogonal projection onto a plane parallel to the second surface, the center line of the second colored portion 131 and the center line of the second non-colored portion 132 coincided with the center line of the first non-colored portion 122 and the center line of the first colored portion 121, respectively.

[0109] Example 2 A copy prevention medium 1 was manufactured in the same manner as in Example 1, except for the following: In this example, the width W1a of the first colored portion 121 was 10 μm, and the width W1b of the first non-colored portion 122 was 10 μm. The width W2a of the second colored portion 131 was 10 μm, and the width W2b of the second non-colored portion 132 was 10 μm.

[0110] Example 3 A copy prevention medium 1 was manufactured in the same manner as in Example 1, except for the following: In this example, the width W1a of the first colored portion 121 was set to 90 μm, and the width W1b of the first non-colored portion 122 was set to 90 μm. The width W2a of the second colored portion 131 was set to 90 μm, and the width W2b of the second non-colored portion 132 was set to 90 μm.

[0111] (Comparative Example 1) A copy prevention medium 1 was manufactured in the same manner as in Example 1, except for the following: In this example, the width W1a of the first colored portion 121 was 150 μm, and the width W1b of the first non-colored portion 122 was 150 μm. The width W2a of the second colored portion 131 was 150 μm, and the width W2b of the second non-colored portion 132 was 150 μm.

[0112] (Comparative Example 2) A copy prevention medium 1 was produced in the same manner as in Example 1, except for the following points: In this example, Lumirror manufactured by Toray, which does not have ultraviolet absorbing properties, was used as the light-transmitting substrate 11.

[0113] The dimensions employed in the copy prevention media 1 according to Examples 1 to 3 and Comparative Examples 1 and 2 are shown in the table below.

[0114] [Table 1]

[0115] <Production of copies> The copy prevention media 1 according to Examples 1 to 3 and Comparative Examples 1 and 2 were printed on a Lumirror film manufactured by Toray Industries using an inkjet color printer to produce copies 2.

[0116] <Rating 1> The results of color discrimination by the naked eye from the first and second sides of the copy prevention media 1 of Examples 1 to 3 and Comparative Examples 1 and 2, and their copies 2 when illuminated with white light, are shown in the table above as Evaluation 1.

[0117] <Rating 2> The results of color discrimination by the naked eye from the first and second sides of the copy prevention media 1 and their copies 2 of Examples 1 to 3 and Comparative Examples 1 and 2 when illuminated with excitation light are shown in the table above as Evaluation 2.

[0118] To judge evaluations 1 and 2, when the images of the authenticity discrimination sections of the copy prevention medium 1 and the copy 2 were observed with the naked eye, if they could be distinguished from each other based on the color difference observed from each other, the evaluation was "Good", and if they could not be distinguished from each other, the evaluation was "Poor".

[0119] When the copy prevention medium 1 and copy 2 of Examples 1 to 3 and Comparative Example 2 were observed under white light, the image could be seen as a mixed color resulting from the arrangement of the first colored portion 121 and the second colored portion 131, but the color difference could not be distinguished with the naked eye.

[0120] On the other hand, when the copy prevention medium 1 and the copy relating to Comparative Example 1 were observed under white light, the width W1a of the first colored portion 121 and the width W2a of the second colored portion 131 were wide enough to be seen, and were observed to be formed in a striped pattern to the naked eye, and could be seen as a printed image consisting of two solid colors rather than a mixed color.

[0121] When the copy prevention medium 1 of Examples 1 to 3 was observed under irradiation with excitation light, the image could be seen as a single color resulting from the first colored portion 121 when observed from the first side, and as a single color resulting from the second colored portion 131 when observed from the second side.In the copy 2, the image was seen as a mixed color resulting from the arrangement of the first colored portion 121 and the second colored portion 131 when observed from both the first side and the second side, and the difference in color could be distinguished with the naked eye.

[0122] When the copy prevention medium 1 according to Comparative Example 1 was observed under irradiation with excitation light, the image could not be seen as a single color originating from the first colored portion 121 when observed from the first side, nor as a single color originating from the second colored portion 131 when observed from the second side; instead, it was seen as a mixed color when observed from either side, making it impossible to distinguish between the copy prevention medium 1 and the copy 2. This is because, although the copy prevention medium 1 according to Comparative Example 1 uses a light-transmitting substrate 11 that is ultraviolet-absorbing, its absorption is not 100%, and the width W1a of the first colored portion 121 and the width W2a of the second colored portion 131 are wide enough to be visible, so the mixed colors were seen due to the influence of reflected light from the side opposite the observation side.

[0123] When the copy prevention medium 1 and copy 2 of Comparative Example 2 were observed under irradiation with excitation light, the images were visible on the first and second sides, respectively, as a mixed color resulting from the arrangement of the first colored portion 121 and the second colored portion 131, and it was not possible to distinguish the color difference between the copy prevention medium 1 and copy 2 with the naked eye.

[0124] As explained above, when the copy prevention medium 1 according to Examples 1 to 3 was observed under irradiation with excitation light, the image was visually recognized as a single color derived from the colored portions of each surface, whether observed from the first or second surface. On the other hand, when the copy 2 was observed from the first or second surface, the image was visually recognized as a mixed color derived from the arrangement of the first and second colored portions, and the color difference between the copy prevention medium 1 and the copy 2 could be distinguished with the naked eye. The invention as originally claimed is set forth below. [1] A copy prevention medium comprising a light-transmitting substrate having a first surface and a second surface opposite to the first surface, the light-transmitting substrate having ultraviolet absorption properties, the first surface having a plurality of first colored portions and a plurality of first non-colored portions arranged alternately, the second surface having a plurality of second colored portions and a plurality of second non-colored portions arranged alternately, and the widths of the first non-colored portions and second non-colored portions being in the range of 5 μm or more and 100 μm or less. [2] Item 1. A copy prevention medium according to item 1, wherein the first colored portion reflects a first colored light, the second colored portion reflects a second colored light, the first colored portion comprises a first colored layer containing a first colored pigment and a first fluorescent pigment that changes color in response to excitation light, and the second colored portion comprises a second colored layer containing a second colored pigment of a different color from the first colored pigment and a second fluorescent pigment of a different color from the first fluorescent pigment. [3] Item 3. A copy prevention medium as described in item 1 or 2, characterized in that the second colored portion is arranged to face the first non-colored portion through a light-transmitting substrate, and the second non-colored portion is arranged to face the first colored portion through a light-transmitting substrate. [4] Item 4. A copy prevention medium according to item 3, wherein the width of the first non-colored portion is smaller than the width of the second colored portion facing the first non-colored portion via a light-transmitting substrate, and the width of the second non-colored portion is smaller than the width of the first colored portion facing the second non-colored portion via a light-transmitting substrate. [5] Item 4. A copy prevention medium according to item 3, wherein the first colored portions and the first non-colored portions have a linear shape and are arranged alternately in the width direction, and the second colored portions and the second non-colored portions have a linear shape and are arranged alternately in the width direction. [6] Item 4. The copy prevention medium according to Item 3, wherein the first colored portion, the first non-colored portion, the second colored portion, and the second non-colored portion have a linear shape. [7] The first colored portion, the first non-colored portion, the second colored portion, and the second non-colored portion have a curved shape. Item 4. A copy prevention medium according to item 3, including a portion having a shape. [8] Item 4. The copy prevention medium according to item 3, wherein the first colored portions form a nested arrangement pattern, and the second colored portions form a nested arrangement pattern corresponding to the first colored portions. [9] Item 4. The copy prevention medium according to item 3, wherein the first colored portions and the first non-colored portions are arranged in a checkerboard pattern, and the second colored portions and the second non-colored portions are arranged in a checkerboard pattern. [Explanation of symbols]

[0125] 1...copy prevention medium, 2...copy, 11...light-transmitting substrate, 12...first colored layer under white light, 13...second colored layer under white light, 14...printed layer, 15...first colored layer under stimulating light, 16...second colored layer under stimulating light, 21...light-transmitting substrate, 22...first colored layer, 23...second colored layer, 121...first colored portion, 122...first non-colored portion, 131...second colored portion, 132...second non-colored portion, 221...dot-shaped portion , 231... dot-shaped portion, IL... illumination light, LS... light source, OB... observer, P1... pitch, P2... pitch, R1A... first printed area, R1B... first non-printed area, R2A... second printed area, R2B... second non-printed area, REF... diffuse reflector, RL... reflected light, TL... transmitted light, W... window, W1a... width of first colored portion, W1b... width of first non-colored portion, W2a... width of second colored portion, W2b... width of second non-colored portion

Claims

1. a light-transmitting substrate having a first surface and a second surface opposite to the first surface, the light-transmitting substrate having ultraviolet absorbing properties; the first surface includes a plurality of first colored portions and a plurality of first non-colored portions arranged alternately; the second surface includes a plurality of second colored portions and a plurality of second non-colored portions arranged alternately; the widths of the first non-colored portion and the second non-colored portion are in the range of 5 μm to 100 μm, the first colored portion reflects first colored light, the second colored portion reflects second colored light, the first colored portion includes a first colored layer containing a first color pigment and a first fluorescent pigment that develops a color in response to excitation light, and the second colored portion includes a second colored layer containing a second color pigment that is different in color from the first color pigment and a second fluorescent pigment that is different in color from the first fluorescent pigment, A copy prevention medium in which the second colored portion is arranged to face the first non-colored portion through a light-transmitting substrate, and the second non-colored portion is arranged to face the first colored portion through a light-transmitting substrate.

2. a width of the first non-colored portion is smaller than a width of the second non-colored portion that faces the first non-colored portion via a light-transmitting substrate; 2. The copy prevention medium according to claim 1, wherein the width of the second non-colored portion is smaller than the width of the first colored portion that faces the second non-colored portion via a light-transmitting substrate.

3. The copy prevention medium of claim 1, wherein the first colored portions and the first non-colored portions have a linear shape and are arranged alternately in the width direction, and the second colored portions and the second non-colored portions have a linear shape and are arranged alternately in the width direction.

4. 2. The copy prevention medium according to claim 1, wherein the first colored portion, the first non-colored portion, the second colored portion, and the second non-colored portion have a linear shape.

5. 2. The copy prevention medium according to claim 1, wherein the first colored portion, the first non-colored portion, the second colored portion, and the second non-colored portion include a portion having a curved shape.

6. 2. The copy prevention medium according to claim 1, wherein the first colored portions form a nested arrangement pattern, and the second colored portions form a nested arrangement pattern corresponding to the first colored portions.

7. 2. The copy prevention medium according to claim 1, wherein the first colored portions and the first non-colored portions are arranged in a checkerboard pattern, and the second colored portions and the second non-colored portions are arranged in a checkerboard pattern.

Images