JP6418592B2 - Anti-counterfeit structure, anti-counterfeit medium, and authenticity discrimination device - Google Patents

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. And, 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, its presence is difficult to distinguish with the naked eye. .

  However, the visual indistinguishable mark printed with ink mixed with heat ray absorbing glass powder or infrared absorbing glass powder was printed with the same color ink not mixed with heat ray absorbing glass powder or infrared absorbing glass powder when observed in detail from diagonally. Since it appears to have lifted from the pattern, its presence may be discriminated by the naked eye. Also, a person with a sharp fingertip sense can know that there is a naked eye indistinguishable mark in the pattern by touching the invisible eye distinguishing mark and the surrounding pattern.

  In addition, if an infrared irradiation device is used, it is possible to easily determine that such a naked eye distinction mark is present in the pattern, and by combining the infrared irradiation device and an infrared camera, the shape can be determined. And you can easily know even the dimensions. Infrared irradiation devices and infrared cameras are relatively widely used and are readily available. Therefore, it is possible to counterfeit the above-mentioned naked eye distinction difficult mark relatively easily.

  Patent Document 1 discloses an infrared absorbing ink that can absorb infrared rays but does not absorb visible light. If an infrared-absorbing ink is used to draw an indistinguishable mark in a pattern printed with the same color ink as the infrared-absorbing ink, even if such an indistinguishable mark is observed in detail from an angle. It does not appear to be lifted from the pattern drawn with the same color ink as the infrared absorbing ink, and its presence is not discriminated by the naked eye. Moreover, even if a person with a sharp fingertip sensation is touched, its presence is not discriminated by the sensation.

  Patent Document 2 prints a mark that is difficult to distinguish with the naked eye using a special fluorescent ink that emits light with a certain wavelength other than visible light, specifically fluorescent light that is not visible in the visible light region and that can be distinguished by ultraviolet rays. It is disclosed. Even if such a visual indistinguishable mark is printed on a pattern printed with the same color ink as that of the special fluorescent ink using the special fluorescent ink, such a visual indistinguishable mark may be observed in detail from an oblique direction. It does not appear to be raised from the pattern printed with the same color ink as the special fluorescent ink, and its presence is not discriminated by the naked eye. Further, even if a person with a sharp fingertip sensation is touched, its presence is not discriminated by touch.

  Patent Document 3 discloses a method using terahertz electromagnetic waves as an authenticity discriminating 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, even when an infrared-absorbing ink described in Patent Document 1 is used to draw a mark that is difficult to distinguish with the naked eye, if an infrared irradiation device that is relatively widely used and easily available is used, Thus, it can be easily determined that the naked eye distinction mark is present in the pattern. Further, by combining the infrared irradiation device and the infrared camera, the shape and dimensions can be easily known. Moreover, even when the visual distinction difficult 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, Thus, it can be easily determined that the naked eye distinction mark is present in the pattern. Further, by combining the ultraviolet irradiation device and the camera, the shape and dimensions can be easily known.

  Furthermore, when the anti-counterfeit structure described in Patent Document 3 is used, the mark for difficult to distinguish with the naked eye is concealed and the anti-counterfeit effect is high, but the device for performing the authenticity determination is complicated and expensive. In addition, since the transmitted waveform is compared with the reference waveform for determination, the determination time tends to be prolonged, and it is difficult to say that the anti-counterfeiting structure and the authenticity determination device are versatile 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 an anti-counterfeit structure, and the anti-counterfeit structure is disposed on one surface of a base substrate capable of transmitting terahertz electromagnetic waves, and is capable of transmitting terahertz electromagnetic waves. An opening forming layer and a conductive layer that is disposed on a surface opposite to the base substrate of the opening forming layer and that blocks terahertz electromagnetic waves are provided. In this forgery prevention structure, the opening forming layer is an electrically insulating layer, and the conductive layer has an opening that forms a predetermined pattern capable of transmitting a terahertz electromagnetic wave having a specific frequency . .

In the anti-counterfeit structure described above, openings that form a predetermined pattern capable of transmitting a terahertz electromagnetic wave having a specific frequency are 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 of the transmitted frequency through the medium, it is possible to quickly determine a mark that is difficult to distinguish with the naked eye (predetermined pattern) at a high speed. Can do. 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 opening forming layer preferably has a light diffraction layer that causes diffraction by light irradiation. 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 opening forming layer, is capable of transmitting terahertz electromagnetic waves, and is capable of peeling each other layer from the base substrate, and a conductive layer. And an adhesive layer that is disposed on a surface opposite to the opening forming layer of the layer and is capable of transmitting the terahertz electromagnetic wave and having 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 anti-counterfeit structure, the conductive layer having an opening that forms a predetermined pattern selectively transmits the terahertz electromagnetic wave with the terahertz electromagnetic wave having a specific frequency as a peak, and transmits half the frequency of the terahertz electromagnetic wave that is transmitted. The value width is preferably 0.2 THz or less. In this case, by suppressing the width of the terahertz electromagnetic wave of a specific frequency, by measuring the before and after of the terahertz electromagnetic wave of a specific frequency, thereby enabling more accurate authenticity judgment.

  In the forgery prevention structure, the predetermined pattern is formed from an opening having a shape in which a part of the ring shape is opened, and a plurality of predetermined patterns having the same shape are preferably arranged at equal intervals. . In this case, in a plurality of predetermined patterns, the angle of the opened part on the ring may be the same, or the angle of the opened part on the ring may be different. When the angle of the opened part is the same, the pattern can be easily created. On the other hand, when the angle of the opened part is different, the transmittance is also different due to the difference in angle, so that the transmittance pattern for determination by the authenticity discriminating device can be made more complicated, and as a result, The forgery prevention effect can be further enhanced.

  The present invention also relates to another anti-counterfeit medium comprising a paper base material or a plastic base material, wherein the anti-counterfeit medium includes at least a part of any of the anti-counterfeit structures described above. It is preferably embedded in a plastic substrate or disposed on a paper substrate or a plastic substrate.

The present invention also relates to an authenticity discrimination device as yet another aspect. This authenticity discrimination device includes an electromagnetic wave generating means capable of generating at least one frequency terahertz electromagnetic wave, an irradiation means for irradiating an object with a terahertz electromagnetic wave having a specific frequency generated by the electromagnetic wave generating means, and a terahertz having a specific frequency transmitted through the object. Conversion means for receiving electromagnetic waves and converting them into transmittance corresponding to the received terahertz electromagnetic waves, transmittance of terahertz electromagnetic waves transmitted by irradiating the anti-counterfeit structure with terahertz electromagnetic waves of a specific frequency , and the anti-counterfeit structure The determination means for determining the difference between the transmittance of the terahertz electromagnetic wave measured in advance as a reference value for the reference value and either the case where the determination means determines that there is a difference or the case where there is no difference A notification means for performing notification according to the determination result.

In the above authenticity discriminating device, the transmittance of the terahertz electromagnetic wave of a specific frequency is measured, and since the authenticity determination is performed based on the transmittance, compared to the case where the entire terahertz electromagnetic wave frequency range is measured or determined, A mark that is difficult to distinguish with the naked eye can be determined at high speed by a simple method.

  When the anti-counterfeiting device moves the anti-counterfeit medium in a predetermined measurement direction, the transmittance of the terahertz electromagnetic wave is measured at regular intervals, and the determination unit measures the variation of the transmittance according to each measured position. The difference may be determined by comparing with a reference value measured in advance, and the notification unit 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.

FIG. 1 is a plan view and an enlarged view of a forgery prevention structure according to the first embodiment of the present invention. 2 is a cross-sectional view taken along the 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 medium such as a gift certificate, FIG. 3A is a plan view thereof, and FIG. Sectional drawing along a bb line is shown. FIG. 4 is a graph showing the transmittance T when the terahertz electromagnetic wave is irradiated to the SRR (Split Ring Resonator) array portion of the anti-counterfeit structure shown in FIG. 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 a diagram showing an outline of an authenticity discriminating apparatus for measuring the transmittance of the forgery prevention structure according to the present invention. FIG. 7 is a plan view and an enlarged view showing a forgery prevention structure according to the second embodiment of the present invention. FIG. 8 is a cross-sectional view taken along the line VIII-VIII of the forgery prevention structure shown in FIG. FIG. 9 is a graph showing a change in transmittance T when a terahertz electromagnetic wave having a specific frequency f ₁ is scanned in the direction of the arrow with respect to the forgery prevention structure shown in FIG. FIG. 10 is a plan view and an enlarged view showing a forgery prevention structure according to the third embodiment of the present invention. FIG. 11 is a graph showing transmittance T when each shape of the SRR array portion of the forgery prevention structure shown in FIG. 10 is irradiated with terahertz electromagnetic waves, and (a) is at 0.10 THz to 0.80 THz. The displacement of the transmittance is shown, and FIG. FIG. 12 is a graph showing a change in transmittance T when the anti-counterfeit structure shown in FIG. 10 is scanned with the terahertz electromagnetic wave having the specific frequency f ₁ shown in FIG. 11 in the direction of the arrow. FIG. 13: is the top view which shows the modification of the forgery prevention structure which concerns on 3rd Embodiment of this invention, and its enlarged view. FIG. 14 is a plan view showing an example of a state in which the forgery prevention structure shown in FIGS. 7 and 10 is transferred to a gift certificate or the like.

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 plan view and a partially enlarged view showing a forgery prevention structure according to the first embodiment, and FIG. 2 is a cross-sectional view of the forgery prevention structure. FIG. 3 is a diagram illustrating an example of a state in which the forgery prevention structure is embedded in a forgery prevention medium such as a gift certificate. 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 units 12 (SRR: Split Ring Resonator) are formed on a base substrate 11, and an SRR array. The portion 12 is formed by arranging a plurality of SRR patterns 13 at equal intervals in the row direction and the column direction. Each SRR pattern 13 has a ring shape in which a part 13a is open (missed), and is substantially C-shaped.

  As shown in FIG. 2, the forgery prevention structure 1 having such an SRR array unit 12 includes a base substrate 11, an opening forming layer 14 formed on the base substrate 11, and an opening forming layer 14. And a conductive layer 15 formed thereon. The SRR pattern 13 constituting the SRR array unit 12 is formed by providing an opening 16 corresponding to the shape of the SRR pattern 13 in the conductive layer 15. That is, the portion corresponding to the ring shape of the SRR pattern 13 is a gap, and the surface layer of the opening forming layer 14 is exposed. Conversely, the open portion 13a of the SRR pattern 13 is a region where the conductive layer 15 remains. The anti-counterfeit structure 1 has the surface on the surface side of the conductive layer 15 exposed to the outside, but when used in an anti-counterfeit medium such as securities, an insulating layer is formed on the conductive layer 15 side. Will be placed.

  The base substrate 11 and the opening forming layer 14 are made of a material that can transmit terahertz electromagnetic waves, and the base substrate 11 is made of, for example, polyethylene terephthalate (PET). For example, it is made of polyurethane resin. By being composed of such a material, the terahertz electromagnetic wave is transmitted through the base substrate 11 and the opening forming layer 14. 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 14 is also an insulating layer. Further, when the anti-counterfeit structure 1 is used in the anti-counterfeit medium 2, the base substrate 11 may be removed, but the SRR pattern 13 by the conductive layer 15 and the opening 16 is opened so as not to be exposed to the outside. The part forming layer 14 is often disposed outside. With this arrangement, the naked eye identification mark can be hidden. The base substrate 11 is a main member that forms a medium.

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 cut and each SRR pattern 13 is provided and the SRR array unit 12 is formed from the plurality of SRR patterns 13, the SRR array unit 12 is irradiated with terahertz electromagnetic waves. By the resonance, for example, a terahertz waveform (transmittance pattern) 33 as shown in FIG. 4 can be observed. The configuration SRR array section 12, such as described above, a portion of the frequency range of the terahertz electromagnetic wave transmission occurs at (frequency band was centered at a particular frequency f ₁ in the figure). The half-value width W1 of the transmittance 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.

Such transmission is achieved by scraping a part of the conductive layer 15 into a predetermined pattern and arranging the SRR patterns 13 at equal intervals, so that resonance with respect to the specific frequency f ₁ occurs, and a specific terahertz electromagnetic wave (specific frequency f ₁ ) Only the frequency band is transmitted. Depending on the shape and arrangement of the pattern of the SRR pattern 13, it is possible to create structures having different transmission peak frequencies and transmission amounts. The transmission peak frequency corresponding to the shape of the SRR pattern 13 is determined by a predetermined simulation device. By using it, those skilled in the art can easily 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.

  Various methods can be used as a method for forming the SRR pattern 13, 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 is provided on the entire surface by forming a water repellent structure in a portion of the diffraction grating formation layer where the conductive layer is to be removed. The conductive layer on the SRR pattern having a water-repellent structure in the conductive layer is removed. If such a forming method is used, also in this embodiment, a diffraction grating can be provided on the conductive layer 15, and anti-counterfeiting can be performed more accurately and at a lower cost than other etching methods. The structure 1 can be manufactured.

  Such a forgery prevention structure 1 can be provided in 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.

When the anti-counterfeit medium 2 configured as shown in FIG. 3 is irradiated with a specific terahertz electromagnetic wave (specific frequency f ₁ ) as shown in FIG. As shown in (b), 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, a transmittance pattern 41 having a high transmittance T is obtained, and the SRR pattern 13 is not present and the conductive layer 15 is formed. In the existing portion, the transmittance pattern 44 has a low transmittance T (or no transmittance) due to the presence of the conductive layer 15. Further, in the SRR array unit 12, the transmittance T of the SRR pattern array is the transmittance pattern 43. It becomes. The transmittance pattern 43 in the 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 SRR array unit 12 does not exist. 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) is used when authenticity is determined by an authenticity determination device (see FIG. 6) described later. 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, the authenticity determination device 100 that performs the authenticity determination of the forgery prevention medium 2 (or the forgery prevention structure 1) using a terahertz electromagnetic wave will be described. FIG. 6 is a schematic diagram showing an authentication 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, for example, 80 fs (f: femto, 10 ⁻¹⁵ ). 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 frequencies 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. When it is determined that there is a difference between the two by the determination in the analysis device 128, the notification device 129 notifies that fact. The notification device 129 may notify the fact when it is determined that there is no difference between the two. 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.

As described above, in the anti-counterfeit structure 1 and the anti-counterfeit medium 2 including the anti-counterfeit structure 1 in the present embodiment, the predetermined frequency that allows the terahertz electromagnetic field having the specific frequency f ₁ to pass through the conductive layer 15 that blocks the terahertz electromagnetic wave. An opening 16 for forming the SRR pattern 13 is provided. Therefore, since, by limiting the terahertz waves transmitted through the specific frequency f _1, it is possible that particular frequency f ₁ is authenticity determination by measuring the transmittance T for transmitting medium for preventing forgery 2, etc., the frequency of the terahertz wave Compared with the conventional method of measuring and scanning the entire area, it is possible to determine a mark that is difficult to distinguish with the naked eye at a high speed by a simple method. In addition, since the naked eye determination difficult mark is arranged inside the layer, the forgery prevention effect is also high.

The pattern of the openings 16 provided in the conductive layer 15 of the anti-counterfeit structure 1 has one size less than or equal to a micro character (a micro character has a side of 0.25 mm). Since it becomes difficult to see the opening 16, security can be improved without apparently changing the forgery prevention medium. Further, the opening forming layer 14 of the forgery prevention structure 1 may be provided with a diffraction grating forming layer (light diffraction layer) that causes diffraction by irradiation with light such as a hologram. In this case, the SRR pattern 13 is 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. 7 is a plan view showing an anti-counterfeit structure according to the second embodiment and an enlarged view thereof, and FIG. 8 is a cross-sectional view of the anti-counterfeit structure. 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.

  The forgery prevention structure 5 is a forgery prevention structure in which the SRR array part 52 is formed on the base substrate 51. Similar to the first embodiment, the SRR array unit 52 is formed by providing an opening 56 in the conductive layer 55. The SRR array unit 52 is formed by arranging a plurality of SRR patterns 53 at equal intervals in the row direction and the column direction. Each SRR pattern 53 has a ring shape in which a part 53a is opened, and is substantially C-shaped.

  Similar to the first embodiment, the forgery prevention structure 5 includes a base substrate 51, an opening forming layer 54, and a conductive layer 55, and further includes a release layer 57, an insulating layer 58, and an adhesive layer 59. ing. The release layer 57 is disposed between the base substrate 51 and the opening forming layer 54, can transmit terahertz electromagnetic waves, and the other layers 54, 55, 58, 59, etc. from the base substrate 51 can be used. It can be peeled off. The insulating layer 58 is an electrically insulating layer having electrical insulating properties, and similarly sandwiches the conductive layer 55 together with the opening forming layer 54 having insulating properties. The adhesive layer 59 is disposed on the surface of the conductive layer 55 opposite to the opening forming layer 54 with an insulating layer 58 interposed therebetween, and can transmit terahertz electromagnetic waves and has adhesiveness. Since the forgery prevention structure 5 has a configuration including the release layer 57 and the adhesive layer 59, the forgery prevention structure 5 can be provided with a function as a transfer foil. For this reason, for example, as shown in FIG. 14, the anti-counterfeit medium 150 can be configured by sticking the adhesive layer 59 on the base material 151 by thermal transfer.

  The conductive layer 55 also has a diffraction grating forming unit 50 so that the pattern of the diffraction grating can be seen visually. Here, when the SRR pattern 53 of the SRR array portion 52 in the forgery prevention structure 5 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 and the terahertz Even if a diffraction grating medium capable of authenticating by electromagnetic waves is exchanged, it cannot be visually confirmed. 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.

By irradiating such anti-counterfeit structure 5 with a specific terahertz electromagnetic wave (specific frequency f ₁ ) in the direction of the arrow as shown in FIG. 9A, as in the first embodiment, A scan pattern 6 having a transmittance T at the specific frequency f ₁ (the pattern 64 in the conductive layer 55 and the pattern 63 in the SRR array unit 52) can be obtained. As in the first embodiment, the authenticity determination can be performed by capturing and comparing the characteristics of this waveform as reference value data by the authenticity determination device 100 in advance. Thus, according to the forgery prevention structure 5, it is possible to achieve the same operational effects as in the first embodiment.

Further, the forgery prevention structure 5 includes a release layer 57 and an adhesive layer 59. For this reason, it is possible to easily manufacture and distribute the anti-counterfeit structure 5 with the base base material 51, and in the actual use, the base base material 51 is easily peeled off from the release layer 57 and bonded. The layer 59 allows easy attachment to a predetermined anti-counterfeit medium.
[Third Embodiment]

Next, a forgery prevention structure according to a third embodiment of the present invention will be described with reference to FIGS. 10 is a plan view showing an anti-counterfeit structure according to the third embodiment and an enlarged view thereof, and FIG. 11 irradiates each shape of the SRR array portion of the anti-counterfeit structure shown in FIG. 10 with terahertz electromagnetic waves. It is a graph which shows the transmittance | permeability T at the time of doing. FIG. 12 is a graph showing a change in transmittance T when a terahertz electromagnetic wave having a specific frequency f ₁ is scanned in the direction of the arrow with respect to the forgery prevention structure shown in FIG. The anti-counterfeit structure 7 according to the third embodiment has the same basic layer configuration as the anti-counterfeit structure 5 according to the second embodiment, and will be described below with a focus on differences.

In the forgery prevention structure 7, as shown in FIG. 10, the SRR patterns 73 to 75 formed by the openings of the conductive layer 55 differ depending on the arrangement locations (areas). An open part 73a is provided above the figure. On the other hand, in the SRR pattern 74, unlike the SRR pattern 73, the open portion 74a is provided so as to be slightly upward, and in the SRR pattern 75, the open portion 75a is further provided in the lateral direction (the left direction in the figure). ing. In the anti-counterfeit structure 7 according to the third embodiment, in this way, in the SRR array unit 72, the shapes of the SRR patterns 73 to 75 are changed by changing the angles of the open portions 73a to 75a, and the transmitted terahertz electromagnetic waves are transmitted. The transmittance T is changed for each of the SRR patterns 73 to 75. In this way, a part of the ring-shaped are arranged at regular intervals in the form which is open, with transmitting frequency of the particular THz radiation so as to cause resonance in the specific frequency as in the second embodiment and the like Furthermore, in this embodiment, the terahertz electromagnetic wave to be irradiated has directivity, and the polarization angle of the terahertz electromagnetic wave that irradiates the angle of the open (missing) portion by irradiating the so-called polarized electromagnetic wave. The transmittance is lowered by an amount corresponding to the shifted angle.

FIG. 11 shows transmittance patterns 82 to 85 obtained by scanning the transmittance T at a specific terahertz frequency with the transmittance shifted in this way. In the graph shown in FIG. 11, the transmittance pattern 83 of the SRR pattern 73 not substantially deviated from the polarization angle of the terahertz electromagnetic wave to be irradiated, the transmittance pattern 84 of the SRR pattern 74 shifted by 35 ° from the polarization angle, and shifted by 60 ° from the polarization angle. A transmittance pattern 85 of the SRR pattern 75 is shown. In FIG. 11, the transmittance pattern 82 when shifted 90 ° from the polarization angle is also shown, in this case, the transmittance in the specific frequency f ₁ becomes lowest.

As described above, in the forgery prevention structure 7 according to the present embodiment, the angle of the chipped portion with respect to the deflection angle of the SRR patterns 73 to 75 is divided into several types and shifted, for example, in the direction of the arrow in FIG. , The scan pattern 9 of the transmittance at the specific frequency f ₁ can be made more complicated so as to include different patterns 91, 94, 93, 95, 91. In the authenticity discriminating apparatus 100, by comparing the scan pattern 9 with such a complicated transmittance change with the reference value, it is possible to make a more complicated authenticity determination. In addition, it is possible to rearrange the patterns of transmittance change, and authenticity determination corresponding to various ticket types is possible. That is, the forgery prevention structure 7 can form a more complex forgery prevention medium. The anti-counterfeit structure 7 may also be provided with the diffraction grating forming unit 70.

  In the forgery prevention structure 7 shown in FIG. 10 and the like, the SRR patterns 73 to 75 having different deviation angles with respect to the polarization angle are arranged along one scanning direction. However, as shown in FIG. In the array unit 112, the anti-counterfeit structure 10 may be configured such that the SRR patterns 73 to 75 are arranged in an area so as to be concentric. In this case, since the same transmittance waveform can be obtained regardless of whether the scanning direction when determining the authenticity of the medium including the anti-counterfeit structure 10 is in the horizontal direction or the vertical direction, the on-site scanning operation can be performed. It can be done easily.

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

  First, a release protective layer composed of the following [Composition of peel protection layer] is provided on a transparent PET having a thickness of 25 μm as a base substrate, and the following [Composition of diffraction grating forming layer] is formed thereon. A diffraction grating forming layer (opening forming layer) was provided with a thickness of 2.0 μm. Thereafter, 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.

  Thereafter, aluminum was provided at a thickness of 60 nm by a vacuum vapor deposition method on the diffraction grating forming layer from which the diffraction grating embossing was obtained. Further, magnesium fluoride was provided thereon as an insulating layer by a 100 nm vacuum deposition method. The film thus obtained is etched with a 1.5N (normal) sodium hydroxide solution, washed with water and neutralized with 0.1N (normal) hydrochloric acid to obtain a predetermined SRR pattern. It was. An adhesive layer comprising the following [Adhesive layer composition] was provided at 2.0 μm thereon to obtain Example 1 of the anti-counterfeit transfer foil.

[Composition of peeling protective layer]
The composition of the peeling protective layer used in the forgery prevention transfer foil according to Example 1 is as follows.
Acrylic resin (BR-116: manufactured by Mitsubishi Rayon Co., Ltd.) 20 parts Solvent (toluene / MEK / ethyl acetate) 40 parts / 35 parts / 5 parts

[Composition of diffraction grating forming layer]
The composition of the diffraction grating forming layer used in the anti-counterfeit transfer foil according to Example 1 is as follows.
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

[Composition of adhesive layer]
The composition of the adhesive used for the forgery-preventing transfer foil according to Example 1 is as follows.
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 Comparative Example 1, a counterfeit sample having a configuration without an SRR pattern among the above configurations was produced.

  The above two types of transfer media are each thermally transferred in several pots by hot stamping onto a gift certificate sample of a paper base material, and a counterfeit prevention medium (Example 1) and a comparison product of the forgery prevention medium (Comparative Example 1). Was made.

  The two types of anti-counterfeit media (Example 1) and the comparison product (Comparative Example 1) of the anti-counterfeit media are exactly the same in appearance and cannot be distinguished, but the authenticity discrimination device 100 shown in FIG. When the transmission waveforms of the above two types of transfer foil portions were measured, the genuine product (Example 1) showed a waveform as shown in FIG. 5, while the counterfeit product (Comparative Example 1) was transferred to the transfer foil portion. Since no transmission of terahertz electromagnetic waves was observed, it was easily distinguished.

DESCRIPTION OF SYMBOLS 1,5,7,10 ... Anti-counterfeit structure, 2 ... Anti-counterfeit medium, 11, 51 ... Base base material, 12, 52 ... SRR array part, 13, 53 ... SRR pattern, 13a, 53a, 73a, 74a, 75a ... Open part, 14,54 ... Opening layer, 15,55 ... Conductive layer, 16,56 ... Opening part, 21 ... Base material, 57 ... Peeling layer, 58 ... Insulating layer, 59 ... Adhesive layer, 100 ... Authenticity discrimination device.

Claims (9)

A base substrate capable of transmitting terahertz electromagnetic waves;
An opening forming layer disposed on one surface of the base substrate and capable of transmitting a terahertz electromagnetic wave;
A conductive layer disposed on a surface opposite to the base substrate of the opening forming layer, and blocking terahertz electromagnetic waves,
The opening forming layer is an electrically insulating layer,
The conductive layer may Propelled by one openings terahertz electromagnetic wave of a specific frequency to form a permeable predetermined pattern, the predetermined pattern from said opening exhibiting a shape in which a part of the ring-shaped is open An anti-counterfeit structure characterized in that a plurality of the predetermined patterns having the same shape are arranged at equal intervals .   The forgery prevention structure according to claim 1, wherein the opening forming layer has a light diffraction layer that causes diffraction by light irradiation. A peeling layer disposed between the base substrate and the opening forming layer, capable of transmitting terahertz electromagnetic waves and capable of peeling the other layers from the base substrate;
The adhesive layer further comprising: an adhesive layer that is disposed on a surface opposite to the opening forming layer of the conductive layer and is capable of transmitting a terahertz electromagnetic wave and having adhesiveness. 2. A forgery prevention structure according to 2. The conductive layer having the opening that forms the predetermined pattern selectively transmits the terahertz electromagnetic wave with the terahertz electromagnetic wave having the specific frequency as a peak, and the half width of the transmittance of the frequency of the transmitted terahertz electromagnetic wave is 0. The anti-counterfeit structure according to any one of claims 1 to 3, wherein the anti-counterfeit structure is at least 2 THz. The forgery prevention structure according to any one of claims 1 to 4 , wherein, in the plurality of predetermined patterns, the angles of the opened portions on the ring are the same. The forgery prevention structure according to any one of claims 1 to 4 , wherein an angle of the opened portion on the ring is different in a plurality of the predetermined patterns. An anti-counterfeit medium comprising a paper substrate or a plastic substrate,
The anti-counterfeit structure according to any one of claims 1 to 6 , wherein at least a part thereof is embedded in the paper base material or the plastic base material, or the paper base material or the plastic base material. An anti-counterfeit medium characterized by being disposed on a material. 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;
Converting means for receiving the terahertz electromagnetic wave having the specific frequency transmitted through the object and converting it into a transmittance corresponding to the received terahertz electromagnetic wave;
The transmittance of the terahertz electromagnetic wave transmitted by irradiating the anti-counterfeit structure according to any one of claims 1 to 6 with the terahertz electromagnetic wave having the specific frequency and the reference value for the anti-counterfeit structure are measured in advance. A determination means for determining a difference from the transmittance of the terahertz electromagnetic wave,
Informing means for informing in accordance with the 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 apparatus comprising: When the anti-counterfeit medium according to claim 7 is moved in a predetermined measurement direction, the transmittance of the terahertz electromagnetic wave is measured at regular intervals, and the determination unit varies the transmittance according to each measured position. Is compared with the reference value measured in advance to determine the difference,
The authenticity determination device according to claim 8 , wherein the notification unit performs notification according to the determination result.

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