JP2016141065A - Forgery prevention structure, forgery prevention medium and authenticity discrimination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forgery prevention structure capable of identifying a mark difficult to be identified by naked eyes at a high speed by the simple method of a high forgery prevention effect.SOLUTION: A forgery prevention structure 1 includes a base material 11 of a base through which a terahertz microwave can be transmitted, an opening forming layer 17 which is disposed on one side of the base material 11 of the base, a conductive layer 15 disposed on a side opposite the base material 11 of the base around the opening forming layer 17, and an insulating layer 18 disposed on the insulating layer 15. The conductive layer 15 includes an opening 14b for forming a first SRR pattern 14 for transmitting the terahertz microwave of a specific frequency, and an opening 16b for forming a second SRR pattern 16 for transmitting visible light while blocking the terahertz microwave of the specific frequency. The opening 16b includes a conductive part having a layer thickness capable of blocking the terahertz microwave of the specific frequency, and the layer thickness of the conductive part is smaller than those of the other parts of the conductive layer 15.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an anti-counterfeit structure for preventing forgery, an anti-counterfeit medium provided with the anti-counterfeit structure, and an authenticity determination device used in combination with an anti-counterfeit structure or an anti-counterfeit medium.

  Conventionally, various devices for preventing counterfeiting have been applied to securities such as stock certificates, bonds, checks, gift certificates, lottery tickets, and commuter passes. As one type of such a device, it is performed to attach a mark for difficult to distinguish with the naked eye to the securities and to read the mark for difficult to distinguish with the machine. The visual recognition difficult mark is printed with, for example, ink mixed with heat ray absorbing glass powder or infrared absorbing glass powder. If such a mark that is difficult to distinguish with the naked eye is mixed in a pattern printed with the same color ink that does not mix heat-absorbing glass powder or infrared-absorbing glass powder, it is difficult to distinguish the presence with the naked eye.

  However, the eye-indistinguishable mark printed with ink mixed with heat-absorbing glass powder or infrared-absorbing glass powder was printed with the same color ink without mixing heat-absorbing glass powder or infrared-absorbing glass powder. Since it appears to have lifted from the pattern, its presence may be discriminated by the naked eye. Further, a person with a sharp fingertip interval can know that the naked eye distinguishable mark exists in the pattern by touching the visually indistinguishable mark and the surrounding pattern.

  By the way, Patent Document 1 discloses an infrared absorbing ink that can absorb infrared rays but does not absorb visible light. If you draw an indistinguishable mark using infrared absorbing ink in a pattern printed with the same color ink as this infrared absorbing ink, even if such a visually indistinguishable mark is observed from diagonally, It does not appear to be lifted from the pattern drawn with the same color ink as the infrared absorbing ink. For this reason, the presence is not discriminated by the naked eye.

  In addition, Patent Document 2 discloses a mark that is difficult to visually recognize using special fluorescent ink that emits light having a certain frequency other than visible light, specifically fluorescent light that is not visible in the visible light region and that can be distinguished by ultraviolet rays. Printing is disclosed. If a mark that cannot be recognized with the naked eye is printed on the pattern printed with the same color ink as that of the special fluorescent ink, such a mark that cannot be detected with the naked eye will be observed in detail from an oblique direction. However, it does not appear to emerge from the pattern printed with the same color ink as the special fluorescent ink. For this reason, the presence is not discriminated by the naked eye.

  Furthermore, Patent Document 3 discloses a method using terahertz electromagnetic waves as an authenticity discrimination device and a forgery prevention structure applied to the method. The forgery prevention structure includes a conductive layer having openings arranged in a predetermined pattern, an insulating layer disposed on the front and back of the conductive layer, and a concealing concealing layer. In the authenticity discriminating apparatus, the measured value when the terahertz electromagnetic wave passes through the forgery prevention structure is compared with a reference value measured in advance to determine whether there is a difference between the two. In this anti-counterfeit structure, the predetermined pattern is concealed by the concealing layer, so that its presence cannot be known with the naked eye or touch.

JP 2000-309736 A JP-A-6-297888 Japanese Patent No. 5110656

  However, an infrared irradiation device that is relatively widely used and can be easily obtained even when the naked eye distinguishable mark is drawn using the infrared absorbing ink that does not absorb visible light described in Patent Document 1. If it is used, it can be easily determined that the naked eye distinction mark is present in the pattern. In addition, by combining the infrared irradiation device and the infrared camera, the shape and dimensions can be easily known. Moreover, even when the naked eye distinguishable mark is drawn using the special fluorescent ink described in Patent Document 2, if an ultraviolet irradiation device that is relatively widely used and easily available is used, It can be easily discriminated that the naked eye distinguishable mark is present in the pattern. Moreover, by combining the ultraviolet irradiation device and the camera, the shape and dimensions can be easily known.

  Further, when the anti-counterfeit structure described in Patent Document 3 is used, the naked eye distinction difficult mark is concealed and the anti-counterfeiting effect is high, but the device for performing the authenticity determination is complicated and expensive. Moreover, since the transmitted waveform is determined by comparing with the reference waveform, the determination time tends to be prolonged, and it is difficult to say that it is a versatile anti-counterfeiting structure and authenticity determination device when it is desired to determine the authenticity in large quantities. .

  Therefore, the present invention has an object to provide a forgery prevention structure, a forgery prevention medium, and an authenticity discrimination device that have a high anti-counterfeit effect and can quickly determine a mark that is difficult to distinguish with the naked eye at a high speed. And

  One aspect of the present invention relates to a forgery prevention structure. The anti-counterfeit structure includes a base substrate capable of transmitting terahertz electromagnetic waves, a first insulating layer disposed on one surface side of the base substrate and capable of transmitting terahertz electromagnetic waves, and a base of the first insulating layer A conductive layer disposed on the side opposite to the substrate side. The conductive layer forms a first opening that forms a first pattern that transmits a terahertz electromagnetic wave having a specific frequency, and a second pattern that forms a second pattern that transmits visible light while blocking the terahertz electromagnetic wave having a specific frequency. Opening.

  In this forgery prevention structure, a first opening that forms a first pattern capable of transmitting a terahertz electromagnetic wave having a specific frequency is provided in the conductive layer that blocks the terahertz electromagnetic wave. In this case, since the authenticity is determined by limiting the frequency of the transmitted terahertz electromagnetic wave and measuring the transmittance at which the terahertz electromagnetic wave having the specific frequency is transmitted through the medium, it is difficult to distinguish the naked eye by a simple method (first pattern). Can be determined at high speed. In addition, when used, the naked eye determination difficult mark is arranged on the inner side, so that the effect of preventing forgery is also high. In the forgery prevention structure, the conductive layer is also provided with a second opening that forms a second pattern that transmits visible light while blocking terahertz electromagnetic waves having a specific frequency. In this case, since the second pattern can be visually recognized by irradiating the second pattern with visible light, it is possible to perform authenticity determination by a very simple verification method.

The forgery prevention structure further includes a second insulating layer disposed on a side of the conductive layer opposite to the first insulating layer, and the conductive layer is sandwiched between the first and second insulating layers. May be laminated. By conductive layer is sandwiched insulating layer, for example, can be slightly shifted towards lower the peak frequency f ₁ of the transmission spectrum as shown in FIG. 4, thereby, can be finely adjusted terahertz waves transmitted through It becomes.

  In the forgery prevention structure, the conductive layer may include a light diffraction layer that causes diffraction by light irradiation in a region where the first opening is formed. In this case, a hologram image can be formed by the light diffraction layer, and the naked eye determination difficult mark can be concealed by the hologram image, so that the forgery prevention effect can be further enhanced.

  The anti-counterfeit structure is disposed between the base substrate and the first insulating layer, and is capable of transmitting terahertz electromagnetic waves and capable of peeling each other layer from the base substrate, and a conductive layer. The adhesive layer may be further provided with an adhesive layer that is disposed on the side opposite to the first insulating layer side and that can transmit the terahertz electromagnetic wave and has adhesiveness. In this case, the presence of the base substrate makes it possible to easily manufacture and distribute the anti-counterfeit structure, and when actually used, the base substrate is easily peeled off by the adhesive layer. It can be easily attached to a predetermined anti-counterfeit medium.

  In the forgery prevention structure, the second opening of the conductive layer is formed in a bottomed shape including a conductive portion having a predetermined layer thickness capable of blocking a terahertz electromagnetic wave having a specific frequency. The layer thickness of the part may be smaller than the layer thickness of the other part of the conductive layer. With this configuration, it is possible to allow the user to visually recognize the second pattern by transmitting visible light while blocking the terahertz electromagnetic wave having a specific frequency.

  In the forgery prevention structure, the first insulating layer has a specific thickness for allowing visible light to pass through while the thickness of the conductive portion constituting the second opening can block terahertz electromagnetic waves having a specific frequency. You may have a structure. In this case, in order to adjust the thickness of the second opening of the conductive layer by previously forming a specific structure on the side of the first insulating layer serving as the base of the conductive layer, the second opening It becomes possible to easily produce a conductive layer including a portion.

  In the forgery prevention structure, at least one of the first and second patterns is formed of an opening having a bridge portion in which the inner side and the outer side of the ring are connected at a part of the ring shape, and has the same shape A plurality of patterns may be arranged at equal intervals. In this case, in the plurality of patterns, the angle of the bridge portion where the inner side and the outer side of the ring are connected may be the same, or in the plurality of patterns, the angle of the bridge portion of the ring may be different. When the angle of the bridge portion is the same, the pattern can be easily created. On the other hand, when the angle of the bridge portion is different, the transmittance is also different depending on the angle, so that the transmittance pattern for determination by the authenticity discriminating device can be made more complicated, and as a result, forgery prevention The effect can be further enhanced.

  Moreover, this invention relates to the forgery prevention medium provided with the paper base material or the plastic base material as another side surface. In this anti-counterfeit medium, any of the anti-counterfeit structures described above is partially embedded in a paper base or plastic base so as to include at least a conductive layer and a first insulating layer, or It may be disposed on a paper substrate or a plastic substrate.

  Moreover, this invention relates to an authenticity determination apparatus as another side surface. The authenticity determination device includes an electromagnetic wave generating unit capable of generating a terahertz electromagnetic wave having at least one frequency, an irradiation unit for irradiating an object with a terahertz electromagnetic wave having a specific frequency generated by the electromagnetic wave generating unit, and a terahertz having a specific frequency transmitted through the object. Conversion means for receiving an electromagnetic wave and converting it into a signal corresponding to the intensity of the received terahertz electromagnetic wave, a signal corresponding to the intensity of the terahertz electromagnetic wave transmitted by irradiating the anti-counterfeit structure with the terahertz electromagnetic wave of a specific frequency, and the above A determination unit that determines a difference between the signal corresponding to the intensity of the terahertz electromagnetic wave that is measured in advance as a reference value with respect to the forgery prevention structure, and a determination that the determination unit determines that there is a difference or no difference And informing means for informing according to the determination result in any of the cases.

  In the above authenticity discriminating apparatus, a signal corresponding to the intensity of the terahertz electromagnetic wave having a specific frequency is measured, and the authenticity determination is performed based on the measured signal. Therefore, when all or most of the frequency range of the terahertz electromagnetic wave is measured and determined. In comparison, it is possible to quickly determine a mark that is difficult to distinguish with the naked eye by a simple method.

  In the authenticity determination device, when moving the anti-counterfeit medium in a predetermined measurement direction, a signal corresponding to the intensity of the terahertz electromagnetic wave is measured at regular intervals, and the determination unit determines the signal corresponding to each measured position. The change may be compared with a reference value measured in advance to determine the difference, and the notification means may perform notification according to the determination result.

  According to the present invention, since at least one frequency of the terahertz electromagnetic wave is specified and the transmittance of the specific frequency transmitted through the medium is determined, the authenticity can be determined at high speed with a simple means. In addition, since a visual recognition pattern (for example, a mark or a symbol) that allows visible light to pass through is also formed, the authenticity can be determined by a simple verification method using visible light.

FIG. 1 is a plan view showing an anti-counterfeit structure according to the first embodiment of the present invention, (a) is a plan view of the anti-counterfeit structure, and (b) is one anti-counterfeit structure. (C) is an enlarged plan view of a second SRR array part which is the other anti-counterfeit structure, and (d) is a plan view of (b). It is an enlarged plan view of the 1st pattern which constitutes the 1st SRR array part shown, (e) is an enlarged plan view of the 2nd pattern which constitutes the 2nd SRR array part shown in (c). . FIG. 2 is a cross-sectional view taken along line II-II of the forgery prevention structure shown in FIG. FIG. 3 is a diagram showing an example of a state in which the forgery prevention structure shown in FIG. 1A is embedded in a paper medium such as a gift certificate, (a) shows a plan view thereof, and (b) shows Sectional drawing along a bb line is shown. FIG. 4 is a graph showing the transmittance T when each SRR array portion of the anti-counterfeit structure shown in FIG. 1A is irradiated with terahertz electromagnetic waves. FIG. 5 is a graph showing a change in transmittance T when the terahertz electromagnetic wave having the specific frequency f ₁ shown in FIG. 4 is scanned in the direction of the arrow with respect to the anti-counterfeit medium shown in FIG. FIG. 6 is an enlarged view showing an example of the surface state of the forgery prevention structure shown in FIG. FIG. 7 is a diagram showing a schematic configuration of an authenticity discrimination device for measuring the transmittance of the forgery prevention structure according to the present invention. FIG. 8 is a plan view and an enlarged view showing a forgery prevention structure according to the second embodiment of the present invention. FIG. 9 is a schematic cross-sectional view taken along the line IX-IX of the forgery prevention structure shown in FIG. FIG. 10 is a graph showing the transmittance T when each shape of the SRR array portion of the anti-counterfeit structure shown in FIG. 8 is irradiated with terahertz electromagnetic waves. FIG. 11 is a graph showing a change in transmittance T when the anti-counterfeit structure shown in FIG. 8 is scanned with the terahertz electromagnetic wave having the specific frequency f ₁ shown in FIG. 10 in the direction of the arrow. FIG. 12 is a plan view showing an example of a state in which the forgery prevention structure shown in FIGS. 8 and 11 is transferred to a gift certificate or the like. FIG. 13 is a schematic view showing a state when visible light is irradiated from the back surface of the forgery prevention medium shown in FIG. FIG. 14 is a perspective view showing an outline of the paper sheet identification and counting apparatus. FIG. 15 is a diagram showing an outline of an identification counting unit included in the paper sheet identification and counting device shown in FIG. 14, (a) is a side view, and (b) is a plan view. FIG. 16 is a diagram illustrating an example of a circuit configuration used for identification processing in the transmission / reception unit of terahertz light.

  Hereinafter, with reference to the accompanying drawings, an anti-counterfeit structure according to the present invention, an anti-counterfeit medium including the anti-counterfeit structure, and an authenticity determination device used in combination with the anti-counterfeit structure or the anti-counterfeit medium The embodiment will be described in detail. In the description, the same reference numerals may be used for the same elements or elements having the same function, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a diagram showing a forgery prevention structure according to the first embodiment, (a) is a plan view of the forgery prevention structure, and (b) is a first forgery prevention structure. FIG. 4 is an enlarged plan view of an SRR (Split Ring Resonator) array portion of FIG. 2, (c) is an enlarged plan view of a second SRR array portion which is the other anti-counterfeit structure, and (d) is (b) (E) is an enlarged plan view of the pattern constituting the SRR array shown in (c). FIG. 2 is a cross-sectional view taken along line II-II of the forgery prevention structure shown in FIG. FIG. 3 is a diagram showing an example of a state in which the forgery prevention structure shown in FIG. 1A is embedded in a paper medium such as a gift certificate, (a) shows a plan view thereof, and (b) shows Sectional drawing along a bb line is shown. The anti-counterfeit structure 1 is a structure for forming a naked eye discrimination difficult mark for preventing forgery in, for example, securities, etc., and is embedded in a gift certificate as shown in FIG. It is used to prevent forgery of forgery prevention media such as gift certificates.

  As shown in FIG. 1A, the forgery prevention structure 1 is a forgery prevention structure in which a plurality of SRR array portions 12 and 13 having no layered conductive layer are formed on a base substrate. For example, one SRR array unit 13 is arranged between a pair of SRR array units 12. The arrangement and number of SRR array units 12 and 13 are not limited to this. As shown in FIG. 1B, the first SRR array unit 12 is formed by arranging a plurality of first SRR patterns 14 on the conductive layer 15 at equal intervals in the row direction and the column direction. Has been. As shown in FIG. 1C, the second SRR array unit 13 is formed by arranging a plurality of second SRR patterns 16 on the conductive layer 15 at equal intervals in the row direction and the column direction. Has been. The planar shapes of the first SRR pattern 14 and the second SRR pattern 16 are, for example, the same, and the inside and outside of the SRR pattern are connected in a bridge shape at portions 14a and 16a (the conductive layer 15 remains). It has a ring shape and is substantially C-shaped. On the other hand, the shapes of the openings 14b and 16b (see FIG. 2) constituting the first SRR pattern 14 and the second SRR pattern 16 are different from each other, and the details will be described below.

  The anti-counterfeit structure 1 including the first SRR array unit 12 and the second SRR array unit 13 is formed on the base substrate 11 and the base substrate 11 as shown in FIG. An opening forming layer 17 (first insulating layer), a conductive layer 15 formed on the opening forming layer 17, and an insulating layer 18 (second insulating layer) covering the conductive layer 15 are provided. ing. The conductive layer 15 is sandwiched between two insulating layers 17 and 18 and stacked. The base substrate 11, the opening forming layer 17 and the insulating layer 18 are made of a material that can transmit terahertz electromagnetic waves. The base substrate 11 is made of, for example, polyethylene terephthalate (PET), and the opening forming layer 17. Is made of, for example, polyurethane resin, and the insulating layer 18 is made of, for example, magnesium fluoride. By being composed of such a material, the terahertz electromagnetic wave is transmitted through the base substrate 11, the opening forming layer 17 and the insulating layer 18. On the other hand, the conductive layer 15 is made of a material that blocks terahertz electromagnetic waves only by that layer. For example, the conductive layer 15 is made of a metal thin film layer such as Al, Fe, Au, Cu, Ag, Mg, Zn, and Sn. Yes. By being composed of such a material, the terahertz electromagnetic wave is blocked by the conductive layer 15. The opening forming layer 17 is also an insulating layer.

  Further, when the opening forming layer 17 is formed using a photopolymer method, the forming material of the opening forming layer 17 is a monomer, oligomer, polymer, or the like having an ethylenically unsaturated bond or an ethylenically unsaturated group. It may be. Examples of the monomer include 1,6-hexanediol, neopentyl glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate. . Examples of the oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate. Examples of the polymer include a urethane-modified acrylic resin and an epoxy-modified acrylic resin.

  The material for forming the opening forming layer 17 may be an ionizing radiation curable resin, and may be, for example, an oxetane skeleton-containing compound, a vinyl ether, and a monomer, oligomer, or polymer having an epoxy group. Good. A photopolymerization initiator may be added to these ionizing radiation curable resins. Depending on the ionizing radiation curable resin to which the photopolymerization initiator is added, the photopolymerization initiator includes a photoradical polymerization initiator, a photocationic polymerization initiator, and a photoradical polymerization initiator and a photocationic polymerization initiator. Any one of the hybrid type polymerization initiators which are the combined type may be selected.

  Examples of the photo radical polymerization initiator include benzoin compounds such as benzoin, benzoin methyl ether and benzoin ethyl ether, anthraquinone compounds such as anthraquinone and methylanthraquinone, acetophenone, diethoxyacetophenone, benzophenone, hydroxyacetophenone, 1-hydroxy Cyclohexyl phenyl ketone, α-aminoacetophenone, and phenyl ketone compounds such as 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, benzyldimethyl ketal, thioxanthone, acylphosphine oxide, and And Michler's ketone.

  Photocationic polymerization initiators include aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, aromatic phosphonium salts, mixed ligand metal salts, and the like.

  The hybrid type polymerization initiator that uses a photoradical polymerization initiator and a photocationic polymerization initiator in combination is, for example, a mixture of the above-described photoradical polymerization initiator and a photocationic polymerization initiator. The hybrid type polymerization initiator may be a polymerization initiator that can initiate both photoradical polymerization and photocationic polymerization alone, such as an aromatic iodonium salt and an aromatic sulfonium salt. It may be.

  When the total amount of the ionizing radiation curable resin and the photopolymerization initiator is 100% by mass, the mass of the photopolymerization initiator is preferably 0.1% by mass or more and 15% by mass or less. The ionizing radiation curable resin may be mixed with a sensitizing dye together with a photopolymerization initiator. In addition, the ionizing radiation curable resin includes dyes, pigments, and various additives such as polymerization inhibitors, leveling agents, antifoaming agents, anti-sagging agents, adhesion improvers, coating surface modifiers, plasticizers, And a nitrogen-containing compound etc. may be added, for example, crosslinking agents, such as an epoxy resin, may be mixed. Further, the ionizing radiation curable resin includes a resin that is non-reactive with respect to the photopolymerization reaction, for example, the above-described thermoplastic resin or thermosetting resin, for the purpose of improving the moldability of the opening forming layer 17. It may be mixed.

  In addition, the ionizing radiation curable resin can be used by mixing with a monomer, an oligomer, a polymer or the like having an ethylenically unsaturated bond or an ethylenically unsaturated group.

  A reactive group may be added in advance to the monomer, oligomer, polymer, and the like mixed with the ionizing radiation curable resin. By adding a reactive group to the monomer, oligomer, polymer, etc., using the isocyanate compound, silane coupling agent, organic titanate crosslinking agent, organic zirconium crosslinking agent, organic aluminate, etc., the monomer, oligomer, In addition, polymers and the like can be cross-linked with each other.

  Furthermore, the reactive group may be previously provided to the monomer, oligomer, polymer, etc. mixed with the ionizing radiation curable resin. By adding a reactive group to the monomer, oligomer, polymer, etc., using the isocyanate compound, silane coupling agent, organic titanate crosslinking agent, organic zirconium crosslinking agent, organic aluminate, etc., the monomer, oligomer, In addition, a polymer or the like can be cross-linked with other resin skeletons.

  Thus, according to the method of crosslinking using a reactive group, it is possible to obtain a polymer having an ethylenically unsaturated bond or an ethylenically unsaturated group, which is solid at normal temperature and has little tack. Is possible. Such a polymer has good moldability and does not easily stain the original.

  Returning to FIG. 1 and FIG. 2, the description will be continued. The first SRR pattern 14 constituting the first SRR array section 12 is formed by providing an opening 14 b (first opening) corresponding to the shape of the first SRR pattern 14 in the conductive layer 15. Has been. That is, the portion corresponding to the ring shape of the first SRR pattern 14 is a gap, and the surface layer of the opening forming layer 17 is exposed. Conversely, the bridge portion 14a of the first SRR pattern 14 is a region (residual portion) where the conductive layer 15 remains.

  The second SRR pattern 16 constituting the second SRR array unit 13 is provided with an opening 16b (second opening) corresponding to the shape of the second SRR pattern 16 in the conductive layer 15. Is formed by. Unlike the case of the first SRR pattern 14, the portion corresponding to the ring shape of the second SRR pattern 16 (opening 16 b) is thinner in the conductive layer 15 than the other portions of the conductive layer 15. The bottomed shape including the conductive portion thus formed is such that the surface layer of the opening forming layer 17 is not exposed. The second SRR pattern 16 transmits visible light while blocking the terahertz electromagnetic wave by the opening 16b having such a layer thickness. For example, when aluminum (Al) is used as the conductive layer 15, the opening 16 b constituting the second SRR pattern 16 has a film thickness of 5 to 40 nm, and transmits visible light while blocking terahertz electromagnetic waves. When the film thickness is 50 nm or more, visible light is blocked and metal reflection is obtained.

  When the anti-counterfeit structure 1 is used in the anti-counterfeit medium 2 as shown in FIG. 3, the base substrate 11 may be removed, but the first due to the conductive layer 15 and the openings 14b and 16b. In many cases, the opening forming layer 17 is disposed on the outside so that the SRR pattern 14 and the second SRR pattern 16 are not exposed to the outside. With such an arrangement, the naked eye identification mark can be hidden inside the anti-counterfeit medium 2. In addition, the conductive layer 15 of the forgery prevention structure 1 may be provided with a diffraction grating forming layer (light diffraction layer) that generates diffraction upon irradiation with light such as a hologram. In this case, the first SRR pattern 14 and the second SRR pattern 16 and the like are further hidden by the hologram or the like, and the forgery prevention effect can be further enhanced.

  Here, “transmitting terahertz electromagnetic waves” does not mean that the output does not change 100% in any frequency range of the terahertz electromagnetic waves before and after passing through the layer, but may transmit 5% or more. For example, this means that "the terahertz electromagnetic wave is transmitted". On the contrary, “the terahertz electromagnetic wave is blocked” means transmission with a transmittance of the terahertz electromagnetic wave of less than 5%, and is not limited to the case where the terahertz electromagnetic wave is blocked by 100% (the transmittance is 0%). .

As described above, when a part of the conductive layer 15 is scraped to provide each first SRR pattern 14 and the first SRR array unit 12 is formed from the plurality of first SRR patterns 14, When the SRR array unit 12 is irradiated with terahertz electromagnetic waves, for example, a terahertz waveform (transmittance pattern) 34 as shown in FIG. 4 can be observed by resonance. By the first SRR array unit 12 having the above-described configuration, transmission occurs in a part of the frequency range of the terahertz electromagnetic wave (frequency range centered on “specific frequency f ₁ ” in the drawing). The full width at half maximum W1 of the frequency of the transmitted terahertz electromagnetic wave is 0.2 THz or less. In this way, if the peak width is small, the characteristic becomes a peculiar one having a large difference in transmittance due to a small difference in frequency (about ± 0.2 THz), and therefore, a plurality of electromagnetic waves having different frequencies (for example, ± 0.2 THz). By measuring this characteristic using a shifted electromagnetic wave, a more accurate authentication can be made.

In such transmission, a part of the conductive layer 15 is scraped into a predetermined pattern, and the first SRR patterns 14 are arranged at equal intervals, whereby resonance with respect to the specific frequency f ₁ occurs, and a specific terahertz electromagnetic wave ( Only the frequency range of the specific frequency f ₁ ) is transmitted. Depending on the shape and arrangement of the pattern of the first SRR pattern 14, it is possible to make structures having different transmission peak frequencies and transmission amounts, and the transmission peak frequency corresponding to the shape of the first SRR pattern 14 is By using a predetermined simulation device, those skilled in the art can calculate. The frequency range of the terahertz electromagnetic wave to be used is determined by the size of the ring. In the present embodiment, for example, the terahertz electromagnetic wave means a range of 0.1 THz to 3 THz (T: tera, 10 ¹² ). The present invention is not limited to this. On the other hand, in the second SRR pattern 16 in which a part of the conductive layer 15 is cut into a predetermined pattern but the predetermined layer thickness is left, as shown in the transmittance pattern 36 shown in FIG. f ₁ is hardly transmitted.

  Here, a method for forming the first SRR pattern 14 and the second SRR pattern 16 will be described in more detail.

  Various methods can be used as a method of forming the first SRR pattern 14, and one method is disclosed in Japanese Patent No. 5169083. The formation method described in this patent document is a formation method using a diffraction grating pattern, and a portion of the opening forming layer 17 where the conductive layer 15 is to be removed is formed with a water-repellent structure so that it is provided on the entire surface. When an etching mask is provided on the conductive layer 15 and the alkali etching is performed, the etching mask is not provided on the first SRR pattern 14 having a water-repellent structure. The layer is removed. If such a formation method is used, a diffraction grating can be provided also on the conductive layer 15 in this embodiment, and the anti-counterfeit structure is more accurate and less expensive than other etching methods. The body 1 can be manufactured.

  Various methods can be used as a method of forming the second SRR pattern 16, and one method is disclosed in Japanese Patent Application Laid-Open No. 2010-202924. The forming method described in this patent document is a method using a mesh-like porous structure. In this method, a region corresponding to a portion (opening portion 16b) in the opening forming layer 17 corresponding to a portion where the film thickness of the conductive layer 15 is to be thinned is formed into a mesh-like porous structure, and at the same time, due to capillary action. Improve wettability. When metal is deposited by a vacuum deposition method when the conductive layer 15 is provided on the entire surface, the thickness of the conductive layer 15 corresponding to the second SRR pattern 16 having a network structure is different from that of the conductive layer 15. The surface area is larger than that of the conductive portion, which can reduce the layer thickness. In addition, by improving the wettability, when an etching mask is applied on the metal vapor-deposited layer, the etching mask is applied on the second SRR pattern 16, and the second SRR pattern 16 is electrically conductive even when alkaline etching is performed. The sex layer remains. As an etching mask to be used, for example, heat-resistant mask layer ink described in Japanese Patent No. 4254367 can be used.

A method for forming the SRR pattern will be described in more detail. FIG. 6 is an enlarged view showing an example of the surface state of the forgery prevention structure shown in FIG. The enlarged portion 1 a of the forgery prevention structure 1 includes a diffraction grating portion 101, an opening 103, and a pattern forming portion 106. The diffraction grating portion 101 corresponds to the conductive layer 15, the opening 103 corresponds to the first SRR array portion 12, and the pattern forming portion 106 is an enlarged view corresponding to the second SRR array portion 13.

  For example, when the spatial frequency of the diffraction grating unit 101 and the pattern forming unit 106 is 1000 lines / mm, the height of the unevenness of the diffraction grating unit 101 is 150 nm, and the height of the concave cone of the pattern forming unit 106 is 400 nm, Since the surface area of the pattern forming unit 106 is about 1.74 times larger than that of the diffraction grating unit 101, for example, when a metal thin film is provided on the diffraction grating unit 101 by 60 nm by vacuum deposition, the pattern forming unit 106 includes A metal thin film of about 35 nm will be provided. In this way, the layer thickness of the second SRR pattern 16 constituting the second SRR array unit 13 in the conductive layer 15 can be made thinner than the layer thickness of the other conductive layers 15.

  The forgery prevention structure 1 having the above-described configuration can be provided on a forgery prevention medium 2 as shown in FIG. 3, for example. In the example illustrated in FIG. 3, the forgery prevention medium 2 is configured by embedding the forgery prevention structure 1 in the base material 21. The base material 21 constituting the forgery prevention medium 2 may be any material that transmits terahertz electromagnetic waves, and is made of, for example, a paper base material or a plastic base material. The anti-counterfeit medium 2 is not necessarily required to be embedded in the base material 21 and the anti-counterfeit structure 1 may be attached to the front surface or the back surface of the base material 21.

As shown in FIG. 5A, a specific terahertz electromagnetic wave (for example, a specific frequency f ₁ ) is irradiated to the forgery prevention medium 2 configured as shown in FIG. When scanning along the arrow direction, as shown in FIG. 5B, a transmittance pattern 4 that is a scan result of the transmittance T at a specific terahertz frequency can be obtained. In the transmittance pattern 4 at the specific frequency f _1, in the base material portion of the base material 21 where the anti-counterfeit structure 1 does not exist, the transmittance pattern 41 has a high transmittance T, and the first SRR pattern 14 is not present. In the portion where the layer 15 is present, the transmittance pattern 45 has a low transmittance T (or no transmittance) due to the presence of the conductive layer 15, and in the first SRR array section 12, the transmittance of the SRR pattern array. In the second SRR array unit 13, the transmittance pattern 46 has a low transmittance T (or no transmittance) in the second SRR array unit 13. The transmittance pattern 44 in the first SRR array unit 12 has a predetermined transmittance, although the transmittance T is lower than the transmittance pattern 41 in the base material 21 in which the first SRR array unit 12 does not exist. Yes. On the other hand, the second SRR array unit 13 blocks the terahertz electromagnetic wave without transmitting it. Then, the characteristics of the waveform of the transmittance T are captured in advance as data, and the acquired waveform data of the transmittance T (transmittance pattern 4) when the authenticity determination device (see FIG. 7) described later determines the authenticity. By comparing the actually read waveform data of the transmittance T and comparing the changes in the transmittance of the two, it is possible to determine the authenticity.

Next, with reference to FIG. 7, a description will be given of an authenticity determination device 100 that performs authenticity determination of the above-described anti-counterfeit medium 2 (or anti-counterfeit structure 1) using terahertz electromagnetic waves. FIG. 7 is a schematic diagram showing an authenticity discrimination device used for authenticating the anti-counterfeit medium 2 (or anti-counterfeit structure 1). The condensing convex lens 126 is arranged at the center so that the anti-counterfeit medium 2 is irradiated with the terahertz electromagnetic wave having the specific frequency f ₁ , and the anti-counterfeit medium 2 is moved in the direction of the arrow (the vertical direction in the figure). During this movement, the transmittance T of the irradiated terahertz electromagnetic wave having the specific frequency f ₁ is read, and compared with the reference value (transmittance pattern 4) of the transmittance T read in advance. Authenticity is determined. In addition, about a detailed determination process, since a prior art can be used suitably, the detailed description is abbreviate | omitted here.

A specific measurement device example of the authenticity determination device 100 is shown below. The authenticity discrimination device 100 includes a laser oscillator 121 (electromagnetic wave generation means), a distributor 122, a PC (photoconductor) antenna (transmission side) 123 (electromagnetic wave generation means), a PC antenna (reception side) 124 (conversion means), and a convex lens 125. , A convex lens 126, a time delay device 127, an analysis device 128 (determination unit), a notification device 129 (notification unit), a reception output 131, and a reference output 132. In this authenticity discriminating apparatus 100, a laser beam of a pulse wave is emitted from the laser oscillator 121 toward the PC antenna (transmission side) 123 by 80 fs (f: femto, 10 ⁻¹⁵ ), for example. When a bias voltage is applied to the PC antenna (transmission side) 123, a current flows through the antenna with the irradiated femtosecond pulse light for a very short time, and a terahertz (THz) band electromagnetic wave is generated. Here, the terahertz electromagnetic wave generated is adjusted to a specific frequency f _1.

This terahertz electromagnetic wave becomes a parallel wave by the convex lens 125 on the transmission side, and is further converged by the convex lens 126. The convex lenses 125 and 126 on the transmission side constitute an irradiating means, and the anti-counterfeit medium 2 as the measurement object is arranged at the most converged portion and moved in the direction of the arrow in the figure, so that the target target is obtained. A terahertz electromagnetic wave having a specific frequency f ₁ is continuously irradiated. The terahertz electromagnetic waves transmitted through the anti-counterfeit medium 2 as a target are collected by a convex lens (parallel light) 126 and a convex lens (condensing) 125 on the reception side, and irradiated to the PC antenna (reception side) 124. The timing of extracting the reception data from the PC antenna 124 on the reception side can be performed by irradiating the reception antenna with the laser beam every certain time ΔT through the laser beam distributor 122 and the time delay device 127. By this principle, a waveform in the time domain every certain time ΔT is obtained. The obtained data can be converted into frequency domain data by Fourier transform. There are many methods other than those described above for detection in the microwave and terahertz wave bands, and any detection method may be used.

  Then, the transmittance T of the terahertz electromagnetic wave transmitted by irradiating the anti-counterfeit medium 2 with the terahertz electromagnetic wave having a specific frequency and the terahertz preliminarily measured with respect to the anti-counterfeit medium 2 (or an equivalent thereof). The difference from the electromagnetic wave transmittance T is determined. If it is determined by the analysis device 128 that the difference between the two is greater than or equal to a predetermined value, the notification device 129 notifies that fact. The notification device 129 may notify the fact when it is determined that the difference between the two is not greater than or equal to a predetermined value. In addition, when moving the anti-counterfeit medium 2 in a predetermined measuring direction, the transmittance T of the terahertz electromagnetic wave is measured at regular intervals, and a reference value obtained by measuring in advance the variation of the transmittance T according to each measured position The notification device 129 may perform notification according to the determination result. Note that the authenticity determination device 100 can also be used in the same manner for authenticating an anti-counterfeit medium using an anti-counterfeit structure according to another embodiment described below.

Thus, in the anti-counterfeit structure 1 and the anti-counterfeit medium 2 including the anti-counterfeit structure 1 in this embodiment, the terahertz electromagnetic wave having the specific frequency f ₁ can be transmitted through the conductive layer 15 that blocks the terahertz electromagnetic wave. An opening 14b for forming one SRR pattern 14 is provided. Therefore, limiting the terahertz waves transmitted through the specific frequency f _1, so that a specific frequency f ₁ can be authenticity judgment by measuring the transmittance T for transmitting medium, measuring the frequency range of all of the terahertz electromagnetic wave In addition, it is possible to determine a mark that is difficult to distinguish with the naked eye at a high speed by a simpler method than the conventional method of scanning. In addition, when used, the naked eye determination difficult mark is arranged on the inner side, so that the effect of preventing forgery is also high. Further, in the forgery prevention structure 1 and the forgery prevention medium 2, an opening 16 b that forms a second SRR pattern 16 that transmits visible light while blocking the terahertz electromagnetic wave having the specific frequency f _{1 in} the conductive layer 15. Is also provided. For this reason, by irradiating the second SRR pattern 16 with visible light, the second SRR pattern 16 (viewing pattern) through which the visible light is transmitted can be seen through, so an extremely simple verification method. It is also possible to perform authenticity determination by

  The pattern of the openings 14b and 16b provided in the conductive layer 15 of the anti-counterfeit structure 1 has a size smaller than or equal to a micro character (a micro character has a side of 0.25 mm). Then, since it becomes difficult to see the openings 14b and 16b, it is possible to improve the security without apparently changing the forgery prevention medium 2. In addition, the conductive layer 15 of the forgery prevention structure 1 may be provided with a diffraction grating forming layer (light diffraction layer) that generates diffraction upon irradiation with light such as a hologram. In this case, the first SRR pattern 14 and the second SRR pattern 16 are further hidden by the hologram or the like, and the forgery prevention effect can be further enhanced.

[Second Embodiment]
Next, a forgery prevention structure according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a plan view showing an anti-counterfeit structure according to the second embodiment and an enlarged view thereof, and FIG. 9 is a cross-sectional view of the anti-counterfeit structure shown in FIG. FIG. 10 is a graph showing the transmittance T when the terahertz electromagnetic wave is irradiated to each shape of the SRR array portion of the forgery prevention structure shown in FIG. FIG. 11 is a graph showing a change in transmittance T when the anti-counterfeit structure shown in FIG. 8A is scanned with a terahertz electromagnetic wave having a specific frequency f ₁ shown in FIG. 10 in the direction of the arrow. In addition, below, description is abbreviate | omitted about the part similar to the forgery prevention structure 1 which concerns on 1st Embodiment, and it demonstrates centering around a different point.

  As shown in FIGS. 8 and 9, the forgery prevention structure 5 includes a first SRR array unit 52, a second SRR array unit 53, and a third SRR array unit 57 formed on a base substrate 61. It is a forgery prevention structure. The first SRR array unit 52 and the third SRR array unit 57 are formed by providing openings 52b and 57b in the conductive layer 55, similarly to the first SRR array unit 12 of the first embodiment. Yes. Similarly to the second SRR array unit 13 of the first embodiment, the second SRR array unit 53 is formed by providing a bottomed opening 53b (having a predetermined layer thickness) in the conductive layer 55. ing.

  As shown in FIG. 8A, the first SRR array unit 52 is formed by arranging a plurality of first SRR patterns 64 at equal intervals in the row direction and the column direction. As shown in FIG. 8A, the second SRR array unit 53 is formed by arranging a plurality of second SRR patterns 66 at equal intervals in the row direction and the column direction. As shown in FIG. 8A, the third SRR array unit 57 is formed by arranging a plurality of third SRR patterns 67 at equal intervals in the row direction and the column direction. The planar shape of the first SRR pattern 64, the second SRR pattern 66, and the third SRR pattern 67 is, for example, the same, and the inside and outside of the pattern are partially connected by a bridge portion (conductive layer) 55 remains) and is substantially C-shaped. On the other hand, in the first SRR pattern 64, the second SRR pattern 66, and the third SRR pattern 67, the angle of the position of the bridge portion in the plane direction is different, and the first SRR pattern 64 and the second SRR pattern are different. In the pattern 66, the bridge portion is on the upper side in the drawing, whereas in the third SRR pattern 67, the bridge portion is inclined obliquely to the left from the upper side in the drawing. Further, the shapes in the stacking direction of the openings constituting the first SRR pattern 64, the third SRR pattern 67, and the second SRR pattern 66 are different from each other as in the first embodiment. The opening 53b of the second SRR pattern 66 is a bottomed conductive portion, and transmits visible light while blocking terahertz electromagnetic waves.

  As in the first embodiment, the forgery prevention structure 5 includes a base substrate 61, an opening forming layer 60, a conductive layer 55, and an insulating layer 58, and further includes a release layer 62 and an adhesive layer 59. ing. The release layer 62 is disposed between the base substrate 61 and the opening forming layer 60, is capable of transmitting terahertz electromagnetic waves, and removes the other layers 60, 55, 58, 59, etc. from the base substrate 61. It can be peeled off. The adhesive layer 59 is disposed on the surface of the conductive layer 55 opposite to the opening forming layer 60 via the insulating layer 58, and can transmit terahertz electromagnetic waves and has adhesiveness. The adhesive layer 59 can be formed from, for example, an adhesive mainly composed of a polyester resin, a urethane resin, an acrylic resin, or a vinyl chloride resin. In the adhesive for forming the adhesive layer 59, for example, any of an adhesion imparting agent, a filler, a softening agent, a thermal light stabilizer, and an antioxidant may be added. The adhesiveness imparting agent is, for example, rosin resin, terpene phenol resin, terpene resin, aromatic hydrocarbon-modified terpene resin, petroleum resin, coumarone / indene resin, styrene resin, phenol resin, or xylene resin. The filler is, for example, zinc white, titanium oxide, silica, calcium carbonate, or barium sulfate. The softener is, for example, process oil, liquid rubber, or plasticizer. The thermal light stabilizer is, for example, a benzophenone series, a benzotriazole series, or a hindered amine series. The antioxidant is, for example, anilide, phenol, phosphite, or thioester. Since the anti-counterfeit structure 5 is configured to include such a release layer 62 and an adhesive layer 59, the anti-counterfeit structure 5 can be provided with a function as a transfer foil. For this reason, for example, as shown in FIG. 12, it can be set as the forgery prevention medium 9 by sticking the adhesive layer 59 on a base material by thermal transfer.

  The conductive layer 55 also has a diffraction grating forming portion 51 so that the pattern of the diffraction grating can be seen visually. Here, the first SRR array unit 52, the second SRR array unit 53 and the third SRR array unit 57 in the forgery prevention structure 5 have the first SRR pattern 64, the second SRR pattern 66 and the third SRR array unit 57. When the SRR pattern 67 is sufficiently small and the area ratio of the conductive layer 55 is 50% or more, only the diffraction grating is visually recognized, and the diffraction grating medium is exchanged with a diffraction grating medium capable of authenticating by terahertz electromagnetic waves. However, it is not understood visually. Thereby, it is possible to change to a forgery prevention medium having high anti-counterfeit resistance without changing the design of the forgery prevention medium.

  Further, unlike the first embodiment, the forgery prevention structure 5 is formed by the opening of the conductive layer 55, and the first SRR pattern 64 and the third SRR pattern 67 differ depending on the arrangement location (area). In the first SRR pattern 64, a bridge portion is provided in the upper part of the ring shape, which is 12 o'clock in the clockwise direction, whereas in the third SRR pattern 67, the first SRR pattern Unlike 64, the bridge portion is provided so as to be slightly upward and in the direction of 10:00. In the anti-counterfeit structure 5 according to this embodiment, in the first SRR array unit 52 and the third SRR array unit 57 as described above, the shape of the first SRR pattern 64 and the third SRR pattern 67 is changed to a bridge unit. The transmittance T of the transmitted terahertz electromagnetic wave is changed between the first SRR pattern 64 and the third SRR pattern 67. In this way, by arranging the ring-shaped part with the inside and outside connected at equal intervals, the frequency of a specific terahertz electromagnetic wave is caused to resonate at a specific frequency as in the first embodiment. In addition, in this embodiment, the terahertz electromagnetic wave to be irradiated has directivity, and the so-called polarized electromagnetic wave is irradiated, so that the connected bridge portion (the conductive layer 55 remains). ) Is shifted from the polarization angle of the terahertz electromagnetic wave to irradiate, so that the transmittance is lowered by the shifted angle.

FIG. 10 shows scanned transmittance patterns 75 to 77 of the transmittance T at the specific frequency f _{1 with} the transmittance shifted in this way. In the graph shown in FIG. 10, the transmittance pattern 75 of the first SRR pattern 64 that is not substantially deviated from the polarization angle of the irradiated terahertz electromagnetic wave, and the transmittance pattern 77 of the third SRR pattern 67 that is deviated 45 ° from the polarization angle. Show. Further, in the graph shown in FIG. 10, the transmittance of the second SRR pattern 66 formed from the opening 53b having a bottomed shape including a conductive portion having a predetermined layer thickness capable of blocking a terahertz electromagnetic wave having a specific frequency. A pattern 76 is also shown. Since the second SRR pattern 66 has a layer thickness that can block terahertz electromagnetic waves, the transmittance is almost zero. The terahertz electromagnetic wave to be radiated has directivity, and when the so-called polarized electromagnetic wave is radiated, the angle of the blocked portion is rotated from the deflection angle of the terahertz electromagnetic wave to be irradiated. The transmittance is lowered by the amount, and when the deflection angle is 90 degrees orthogonal, the transmittance is the lowest.

For such forgery prevention structure 5, by irradiating the certain THz radiation in the direction of the arrow as shown in FIG. 11 (a specific frequency f _1), as in the first embodiment, a specific frequency f ₁ The transmittance pattern 8 of the transmittance T in (the first SRR pattern 64, the second SRR pattern 66, and the third SRR pattern 67 in the conductive layer 55) can be obtained. Specifically, in the transmittance pattern 8 of FIG. 11B, the base material portion where the anti-counterfeit structure 5 does not exist has a transmittance pattern having a high transmittance T, and the first SRR shown in FIG. In a portion where the conductive layer 55 is present without the pattern 64, the transmittance pattern 85 shown in FIG. 11B is obtained because the transmittance T is low (or no transmittance) due to the presence of the conductive layer 55. Then, in the first SRR array unit 52, the transmittance T of the first SRR pattern array becomes a high transmittance pattern 84, and in the second SRR array unit 53, the transmittance T of the SRR pattern array is The transmittance pattern 86 is low (or has no transmittance). Further, in the third SRR array unit 57 in which the angle of the bridge unit is changed, the transmittance pattern 87 having a predetermined transmittance is obtained although it is lower than the transmittance pattern 84 of the first SRR array unit 52. Then, in the transmittance pattern 85 outside the third SRR array portion 57, the transmittance T is lowered again by the conductive layer 55 of FIG. In this embodiment, by rearranging the pattern of transmittance change in this way, it becomes possible to perform more complex authentication than in the first embodiment, and authentication can be performed corresponding to various types of bills. .

  The first SRR array unit 52, the second SRR array unit 53, and the third SRR array unit 57 of the forgery prevention structure 5 are formed to be marks or symbols depending on the arrangement of the respective SRR patterns. It may be. Then, when the forgery prevention structure 5 is transferred to paper and the anti-counterfeit medium 9 as shown in FIG. 12 is produced, as shown in FIG. Alternatively, since the SRR patterns 5a arranged in a symbol form can be seen through, the authenticity can be determined by a simple verification method. The same can be done in the first embodiment.

Thus, in the forgery prevention structure 5 according to the present embodiment, as shown in FIG. 11A, a specific terahertz electromagnetic wave (specific frequency f ₁ ) is generated in the vertical direction of the drawing along the direction of the arrow. By irradiating, the transmittance pattern 8 at the specific frequency f ₁ can be obtained as in the first embodiment. As in the first embodiment, the feature of the waveform is previously acquired as reference value data by the authenticity discriminating apparatus 100 and compared, so that the authenticity determination by the forgery prevention structure 5 becomes possible. Thus, according to the forgery prevention structure 5, it is possible to achieve the same operational effects as in the first embodiment. In addition, in the transmittance pattern 8 according to the present embodiment, the first SRR pattern 64 is provided such that a portion of the transmittance pattern 84 having a high scanned transmittance T and a transmittance pattern 87 slightly lower than that are provided. And the angle of the bridge part of the 3rd SRR pattern 67 is changed. For this reason, according to the anti-counterfeit structure 5 according to the second embodiment, it is possible to obtain a more complex transmittance pattern than the anti-counterfeit structure 1 according to the first embodiment. There is an effect.

  Further, the forgery prevention structure 5 includes a release layer 62 and an adhesive layer 59. For this reason, the manufacturing and distribution of the anti-counterfeit structure 5 can be easily performed by the base substrate 61 and, when actually used, the base substrate 61 is easily peeled off from the release layer 62 and bonded. The layer 59 allows easy attachment to a predetermined anti-counterfeit medium.

  Here, another example of the apparatus configuration for obtaining the signal of the transmittance pattern 8 shown in FIG. 11B will be described. As an example of such a device configuration, for example, a paper sheet identification and counting device can be cited.

  For example, as shown in FIG. 14, the paper sheet identification and counting apparatus 200 puts paper sheets into the placement unit 214, and identifies and counts the types of the paper sheets by the identification counting unit 210 (see FIG. 15). This is a device that selectively sends paper sheets to the stacking unit 216 or the rejecting unit 217 based on the identification result. The paper sheet identification and counting apparatus 200 includes a housing 212, a placement unit 214 on which a plurality of paper sheets P to be counted are placed in a stacked state, and a stacked state in which the placement unit 214 is placed. The sheet P in the lowermost layer among the sheets P is fed out one by one into the housing 212, and one sheet P is fed into the housing 212 by the feeding unit. A transport unit for transporting the sheets one by one. In addition, the conveyance unit is provided with an identification counting unit 210 for identifying and counting the paper sheet P fed from the placement unit 214 into the housing 212.

  Next, the configuration of the identification counting unit 210 will be described with reference to FIG. FIG. 15A is a side view showing a schematic configuration of the identification counter 210, and FIG. 15B is a plan view thereof. As shown in FIGS. 15 (a) and 15 (b), the identification counting unit 210 is configured with a timing sensor 220 (220a, 220b), a line sensor 221, sequentially from the upstream side (the right side in the drawing) in the transport direction of the paper sheet P. A thickness detection sensor 222, a magnetic head 224, a terahertz light transmission / reception unit 226 (226Sa, 226Sb, 226Ra, 226Rb), and a timing sensor 228 (228a, 228b) are provided. The paper sheet P transported in the identification counting unit 210 is transported in the transport direction indicated by the arrow.

  A pair of timing sensors 220a and 220b are provided on the left and right sides in the conveying direction of the paper sheet P at the most upstream side in the identification counting unit 210, and the paper sheet P is detected by the timing sensor 220a and 220b. It is detected that A line sensor 221 is provided on the downstream side of the timing sensors 220a and 220b in the conveyance direction of the paper sheet P. The line sensor 221 includes light emitting units 221a and 221b and a light receiving unit 221c provided so as to sandwich the transport path of the paper sheet P, and light emitted from the light emitting units 221a and 221b (for example, red light or red light). External light) is received by the light receiving unit 221c. Here, when the paper sheet P is sent to the line sensor 221, the light irradiated from the light emitting unit 221a is reflected by the paper sheet P in the line sensor 221 or irradiated from the light emitting unit 221b. The light passes through the paper sheet P in the line sensor 221 and reaches the light receiving unit 221c, and template matching is performed based on the light data received by the light receiving unit 221c. By this template matching, the type and conveyance direction of the paper sheet P are specified.

  A thickness detection sensor 222 is provided on the downstream side of the line sensor 221 in the conveyance direction of the paper sheet P. The thickness detection sensor 222 can detect the thickness of the paper sheet P, so that there is a folded portion of the paper sheet P or whether two or more paper sheets P are double-fed. Alternatively, it is detected whether a tape or the like is stuck on a portion where the paper sheet P is present.

  A magnetic head 224 is provided on the downstream side of the thickness detection sensor 222 in the conveyance direction of the paper sheet P. The magnetic head 224 detects the magnetism emitted from the magnetic component contained in the ink or the like of the paper sheet P. A detection value related to the magnetism of the paper sheet P is calculated by the magnetic head 224.

A terahertz light transmission / reception unit 226 is provided downstream of the magnetic head 224 in the transport direction of the paper sheet P. The transmission / reception unit 226 includes transmission units 226Sa and 226Sb and reception units 226Ra and 226Rb. Configured. Each of the transmission / reception units 226Sa, 226Sb and 226Ra, 226Rb is provided with a passage on the left and right in the width direction orthogonal to the transport direction of the paper sheet P, and constitutes a transmissive terahertz light sensor. A plurality of the terahertz light transmission / reception units 226 are provided in this way, and may be arranged, for example, in a direction intersecting the conveyance direction of the paper sheet P, or may be arranged along the conveyance direction. Furthermore, it may be used alone. As described above, the terahertz light transmitting / receiving unit 226 transmits terahertz light having a predetermined frequency (for example, frequency f ₁ ) from the transmitters of the transmission units 226Sa and 226Sb. Then, the terahertz light transmitted through the paper sheet P is received by the receivers of the receiving units 226Ra and 226Rb. The terahertz light transmission / reception unit 226 obtains a reference transmission pattern by measuring the transmitted light amount of the terahertz light transmitted through the reference plate with the reference plate facing the conveyance path before passing the paper sheet P. Next, the transmitted light amount of the terahertz light transmitted through the paper sheet P is measured to obtain a transmission pattern. By passing the terahertz light through the wire grid inside the transmission / reception unit 226, the polarization direction of the terahertz light is aligned in one direction, and the intended transmitted light amount of the forgery prevention structure 5 included in the paper sheet P can be obtained. . Further, in order to identify the difference in the transmitted light amount depending on the area inside the forgery prevention structure 5, the half width of the irradiated portion of the terahertz light is smaller than the width of any area where the transmitted light amount inside the forgery prevention structure 5 is different.

  A timing sensor 228 is further provided on the downstream side of the transmission / reception unit 226 in the conveyance direction of the paper sheet P. The timing sensor 228 includes timing sensors 228 a and 228 b provided on the left and right in the width direction orthogonal to the conveyance direction of the paper sheet P. The timing sensors 228 a and 228 b detect that the paper sheet P is sent from the paper sheet identification / counter 200. In the paper sheet identification / counting apparatus 200 having such a configuration, the conveyance unit branches into two conveyance paths at a location downstream of the identification / counting unit 210, and the accumulation unit is included in one conveyance path. 216 is connected to the other side, and a reject unit 217 is connected to the other side. The paper sheet P identified and counted by the identification counting unit 210 is selectively sent to the stacking unit 216 or the rejection unit 217 by the transport unit. An opening is provided in the front surface of the stacking unit 216, and the operator can take out the genuine paper sheets P stacked on the stacking unit 216 through the opening. The front surface of the reject unit 217 may have the same configuration.

  Here, the identification processing in the terahertz light transmission / reception unit 226 will be described in more detail with reference to FIG. As shown in FIG. 16, the terahertz light transmitting / receiving unit 226 receives the terahertz oscillator 226S, the terahertz receiver 226R, the control circuit 226a that controls the applied voltage to the terahertz oscillator 226S, and the terahertz receiver 226R. An amplification circuit 226b that amplifies the signal, an AD converter 226c that AD-converts the amplified signal, and an identification processing unit 226d are provided. In the transmission / reception unit 226, first, a predetermined voltage is applied by a control circuit 226a to an element that oscillates and outputs a terahertz wave by applying a voltage, for example, a terahertz oscillator 226S that is a resonant tunnel diode. The terahertz wave oscillated and output by this voltage application is received by a receiving element that outputs a DC voltage as an output value, for example, a terahertz receiver 226R that is a Schottky barrier diode. The received terahertz light reception signal is amplified by the amplifier circuit 226b, and then AD-converted by the AD converter 226c, and the discrimination processing unit 226d performs discrimination processing based on the magnitude and change amount of the signal. In the terahertz light transmission / reception unit 226, the control circuit 226a is adjusted so as to receive terahertz light of a predetermined intensity by a count start signal triggered by pressing a count button (not shown). Then, the conveyance of the paper sheet P including the forgery prevention structure 5 is started, and when the paper sheet P is detected by the timing sensor 220, the received signal is amplified at predetermined intervals, and the amplified signal is AD converted. Used for reading and identification processing. Signal processing as shown in FIG. 11B can be obtained by signal processing with such a circuit configuration. Then, the authenticity determination of the paper sheet P is performed by comparing the received light amount pattern of the terahertz light determined for each type of the paper sheet P with the received light amount pattern of the terahertz light of the inspection paper sheet. When it is determined to be “false”, a path switching signal is output from the control unit, and the corresponding paper sheet is sent to the reject unit 217. At this time, a display indicating that the ticket is a fake ticket may be displayed, or a notification such as notification by sound may be performed. The received light quantity pattern determination can be compared using the waveform of FIG. 5B or FIG. 11B as a reference pattern. The “transmittance” described in this specification is the “light reception amount”, “light reception intensity” or “light reception signal magnitude” of the terahertz electromagnetic wave when the amount of light reception of the terahertz electromagnetic wave is constant when no medium is present. Can be replaced.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.

First, on a 19 μm transparent PET as a base substrate, a peel protective layer comprising the following [Composition of peel protective layer] was provided with a thickness of 1.0 μm.
[Composition of peeling protective layer]
Acrylic resin (BR-116: manufactured by Mitsubishi Rayon Co., Ltd.) 20 parts Solvent (toluene / MEK / ethyl acetate) 40 parts / 35 parts / 5 parts

Next, a diffraction grating forming layer composed of the following [composition of diffraction grating forming layer] was provided on the release protective layer with a thickness of 2.0 μm. Further, a predetermined diffraction grating plate (roll shape) was pressed onto the diffraction grating forming layer at 160 ° C. and a line thickness of 40 kg / cm to obtain a diffraction grating emboss.
[Composition of diffraction grating forming layer]
25 parts of vinyl chloride-vinyl acetate copolymer (Solvine CH: manufactured by Nissin Chemical Industry Co., Ltd.)
10 parts of urethane resin (Coronate T-100: manufactured by Nippon Polyurethane Industry Co., Ltd.)
MEK 70 parts Toluene 30 parts

Subsequently, 60 nm thick aluminum was provided as a conductive layer thereon by vacuum deposition. An etching mask layer made of the following [etching mask layer composition] was provided as an etching mask layer with a thickness of 1.0 μm thereon.
[Composition of etching mask layer]
Vinyl chloride-vinyl acetate copolymer (Solvine C: manufactured by Nissin Chemical Industry Co., Ltd.) 30 parts MEK 70 parts

This film was etched with a 1.5N sodium hydroxide solution, washed with water, and neutralized with 0.1N hydrochloric acid to obtain a predetermined SRR pattern. An anti-counterfeit transfer foil was obtained by providing 2.0 μm of an adhesive layer / insulating layer having the following [Adhesive layer composition].
[Composition of adhesive layer]
30 parts of vinyl chloride-vinyl acetate copolymer (Solvine C: manufactured by Nissin Chemical Industry Co., Ltd.)
20 parts of polyester resin (Byron 200: manufactured by Toyobo Co., Ltd.)
MEK 25 parts Toluene 25 parts

  As a comparative example, a counterfeit sample having a configuration without the SRR pattern among the configurations of the above examples was also produced.

  The above-mentioned two types of transfer media were each thermally transferred in several pots by hot stamping on a paper voucher sample of a paper base material to produce an example of anti-counterfeit media and a comparative example of anti-counterfeit media.

  The examples of the two types of anti-counterfeit media and the comparative example of the anti-counterfeit media are visually indistinguishable, but when an anti-counterfeit medium as shown in FIG. More light was transmitted and the predetermined mark could be seen, but no mark appeared in the comparative example. Further, when the transmission waveforms of the above two types of transfer foil portions were measured by the authenticity discriminating apparatus of FIG. 7, the waveforms shown in FIG. 5B were shown in the example, but in the comparative example, the transfer foil portions were shown. Since no transmission of terahertz electromagnetic waves was observed, the distinction between the two (authenticity) could be easily determined.

  DESCRIPTION OF SYMBOLS 1,5 ... Anti-counterfeit structure, 2,9 ... Anti-counterfeit medium, 11, 61 ... Base base material, 12, 52 ... First SRR array part, 13, 53 ... Second SRR array part, 14, 64 ... 1st SRR pattern, 14b, 52b, 57b ... Opening (first opening), 15, 55 ... Conductive layer, 16, 66 ... 2nd SRR pattern, 16b, 53b ... Opening (2nd) , 17, 60... Opening formation layer (first insulating layer), 18, 58... Insulating layer (second insulating layer), 57... Third SRR array portion, 59. ... peeling layer, 67 ... third SRR pattern, 100 ... authenticity discriminating device.

Claims (12)

A base substrate capable of transmitting terahertz electromagnetic waves;
A first insulating layer disposed on one side of the base substrate and capable of transmitting terahertz electromagnetic waves;
A conductive layer disposed on a side opposite to the base substrate side of the first insulating layer,
The conductive layer forms a first opening that forms a first pattern that transmits a terahertz electromagnetic wave having a specific frequency, and a second pattern that transmits visible light while blocking the terahertz electromagnetic wave having a specific frequency. An anti-counterfeit structure having a second opening. A second insulating layer disposed on the opposite side of the conductive layer from the first insulating layer side;
The forgery prevention structure according to claim 1, wherein the conductive layer is sandwiched and laminated between the first and second insulating layers.   The forgery prevention structure according to claim 1, wherein the conductive layer has a light diffraction layer that causes diffraction by light irradiation in a region where the first opening is formed. A peeling layer disposed between the base substrate and the first insulating layer, capable of transmitting terahertz electromagnetic waves and capable of peeling the other layers from the base substrate;
4. The method according to claim 1, further comprising: an adhesive layer that is disposed on a side opposite to the first insulating layer side of the conductive layer, is capable of transmitting terahertz electromagnetic waves, and has adhesiveness. An anti-counterfeit structure according to one item.   The second opening of the conductive layer is formed in a bottomed shape including a conductive part having a predetermined layer thickness capable of blocking the terahertz electromagnetic wave of the specific frequency, and the layer thickness of the conductive part is The forgery prevention structure according to any one of claims 1 to 4, wherein the anti-counterfeit structure is thinner than a layer thickness of another part of the conductive layer.   The first insulating layer has a specific structure for allowing a thickness of a conductive portion constituting the second opening to transmit visible light while allowing a terahertz electromagnetic wave having the specific frequency to be blocked. Item 6. The forgery prevention structure according to any one of Items 1 to 5.   At least one of the first and second patterns is formed from an opening having a bridge portion in which a ring-shaped part is connected to the inside and the outside, and a plurality of the patterns having the same shape are arranged at equal intervals. The forgery prevention structure according to any one of claims 1 to 6, which is arranged.   The forgery prevention structure according to claim 7, wherein the angles of the bridge portions on the ring are the same in the plurality of patterns.   The forgery prevention structure according to claim 7, wherein in the plurality of patterns, the angles of the bridge portions on the ring are different. An anti-counterfeit medium comprising a paper substrate or a plastic substrate,
The anti-counterfeit structure according to any one of claims 1 to 9, wherein a part of the anti-counterfeit structure is included in the paper base material or the plastic base material so as to include at least the conductive layer and the first insulating layer. An anti-counterfeit medium that is buried or disposed on the paper substrate or the plastic substrate. Electromagnetic wave generating means capable of generating terahertz electromagnetic waves of at least one frequency;
An irradiating means for irradiating an object with a terahertz electromagnetic wave having a specific frequency generated by the electromagnetic wave generating means;
Conversion means for receiving the terahertz electromagnetic wave having the specific frequency transmitted through the object and converting the signal into a signal corresponding to the intensity of the received terahertz electromagnetic wave;
A signal corresponding to the intensity of the terahertz electromagnetic wave transmitted by irradiating the terahertz electromagnetic wave of the specific frequency to the anti-counterfeit structure according to any one of claims 1 to 9, and a reference value for the anti-counterfeit structure Determining means for determining a difference from the signal corresponding to the intensity of the terahertz electromagnetic wave measured in advance as
An output means for performing an output according to a determination result when the determination means determines that there is the difference or when it is determined that there is no difference;
An authenticity discriminating device. When the anti-counterfeit medium according to claim 10 is moved in a predetermined measurement direction, a signal corresponding to the intensity of the terahertz electromagnetic wave is measured at regular intervals, and the determination unit is a signal corresponding to each measured position. To determine the difference by comparing the fluctuation of
The notification means performs output according to the determination result.
The authenticity discrimination device according to claim 11.

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