JP2019175220A - Identification tag, its manufacturing method, its interference waveform detection method and its authenticity determination method - Google Patents

Abstract

To provide an identification tag capable of economically manufacturing and hard to forge.SOLUTION: This identification tag is made from a thermoplastic material which terahertz wave can be reflected against or transmit through, and has a flat plate structure where a plurality of regions having different thickness are combined. The identification tag can be economically manufactured in a step for creating a block copy of a pattern where a plurality of the regions are combined, a step for pressing a thermal head to the thermoplastic material just like the block copy, and a method in which at least one of pressure, time, heat quantity for pressing the thermal head is controlled for each region, to form a plurality of the regions having different thickness.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an identification tag suitable for use as a tag for various products, a manufacturing method thereof, an interference waveform detection method thereof, and an authenticity determination method thereof.

  There are various types of product tags, but tags that simply describe information such as product name, product number, and price are easily forged. For this reason, conventionally, in order to identify a tag of a product, a tag having a complicated pattern such as a bar code or QR code (registered trademark), a memory such as an RF tag, a control circuit, Tags have been developed that can be used for product identification by incorporating an antenna and reading it with electromagnetic waves.

  The identification tag in this invention points out the structure which has the forgery prevention effect by giving discrimination power to goods or a thing like the said goods tag. Targets of structures that have discriminatory and anti-counterfeiting effects are broadly interpreted and include those for identifying products distributed in manufacturing, mining, agriculture, fishery and transportation, finance, commerce, service industries, etc. It is. Further, the present invention is not limited to identifying goods such as clothes and food that are distributed in large quantities to general consumers, and extends to identifying arts and crafts that are not distributed in large quantities. Further, the object is not limited to identifying a product distributed to general consumers, and may be, for example, for identifying a semi-finished product during a manufacturing process in the manufacturing industry. In addition, the shape of the identification tag can be various forms such as those attached directly to the product or those attached to the product via a tag holder or the like.

  For example, in Patent Document 1, an information code is configured by combining a large number of recesses having different depths from a reference plane, and the surface is irradiated with a laser beam to receive reflected light and measure the distance from the reference plane. Thus, an identification tag for reading the information code is described. However, since the laser rangefinder is a general device, the information code can be read and forged relatively easily.

  Patent Document 2 describes a terahertz anti-counterfeit structure for forming a conductive pattern having an opening on a substrate and irradiating terahertz waves to detect the intensity of the interference waves. Although a terahertz wave generator is disclosed in Patent Document 3, it is not as common as a laser rangefinder, so that it is difficult to read an information code. However, since the technique of Patent Document 2 has a limited pattern to be created, the pattern may be decoded by disassembling the base material.

  In addition, there is an RF tag as a tag that can be read through the shield, but this requires the provision of an antenna for receiving radio waves or magnetic fields in the tag material. When the distance between the antennas is short, there has been a problem that reading and writing cannot be performed due to interference between the antennas in the tag.

Japanese Patent No. 4967778 Japanese Patent No. 5119656 JP 2002-72269 A

  Therefore, the present inventors are developing an identification tag for terahertz that has a forgery prevention effect enhanced by changing the thickness for each specific region and complicating the pattern. As a specific manufacturing method, a method in which block-shaped transmission materials having different thicknesses are bonded together, a method in which a resin material or the like is injected into an injection mold or a compression mold, and the like are considered. However, the former method of pasting blocks requires time and effort, and the latter method using a mold is expensive to produce a mold, so it is not possible to produce a large variety of products in small quantities, and manufacturing an identification tag for authenticity judgment Had the problem of being inappropriate. Accordingly, an object of the present invention is to provide an identification tag that can be manufactured economically and is not easily counterfeited.

In order to solve the above problems, the following means (1) to (5) are adopted in the present invention.
(1) An identification tag comprising a flat plate structure made of a thermoplastic material capable of reflecting or transmitting terahertz waves and combining a plurality of regions having different thicknesses.
(2) The identification tag of (1), wherein the thermoplastic material is a porous material.
(3) A step of creating a pattern with a combination of a plurality of regions, and a step of pressing a thermal head on the plate-like body made of a thermoplastic material capable of reflecting or transmitting a terahertz wave, as in the case of the plate, A method for manufacturing an identification tag, wherein a plurality of regions having different thicknesses are formed by controlling at least one of pressure, time, and amount of heat applied to the thermal head for each region.
(4) Terahertz waves having different frequencies are irradiated on the identification tag of (1) or (2), reflected or transmitted on the front and back surfaces of the identification tag, and interfered by an optical path difference, the identification tag A method for detecting an interference waveform of an identification tag, comprising: detecting from the irradiation side or the back side of the laser beam, and converting the detected terahertz wave into waveform data representing transmittance for each frequency.
(5) The authenticity of the identification tag structure characterized by determining the authenticity of the identification tag by comparing the waveform data obtained by the waveform detection method of (4) with reference waveform data stored in advance. Judgment method.

  The identification tag structure of the present invention is to perform authenticity determination using a terahertz wave that has not been widely used as a generator, and it is only necessary to make the thickness of each region slightly different. Even if it is decomposed, there is an advantage that the pattern is difficult to decipher and it is difficult to forge. In addition, terahertz waves can be read through shields because they appropriately transmit various substances such as paper, plastic, vinyl, fibers, semiconductors, and powders. For example, an identification tag is placed inside the product packaging. It is possible to arrange products and prevent counterfeiting. Furthermore, the identification tag of the present invention does not have an antenna for receiving radio waves or magnetic fields inside the identification tag, and does not cause interference between the antennas. In addition, product identification and forgery prevention can be performed. Further, according to the identification tag manufacturing method of the present invention, an identification tag in which a large number of regions having different thicknesses are combined in a complicated manner can be economically manufactured using a thermal head. Furthermore, according to the authenticity determination method of the present invention, a slight difference in thickness also appears as a difference in waveform data, so authenticity determination can be performed reliably.

It is explanatory drawing which shows reflection and permeation | transmission of a terahertz wave. It is a graph of an interference waveform obtained by frequency analysis of a transmitted wave. It is a schematic diagram of the identification tag of this invention. It is a graph of the interference waveform corresponding to a different frequency. It is explanatory drawing of a use state.

Embodiments of the present invention will be described below.
The identification tag of the present invention is a flat plate made of a thermoplastic material that can reflect or transmit terahertz waves. The terahertz wave is an electromagnetic wave having a wavelength of 30 μm to 1 mm (frequency: 300 GHz to 10 THz), and has a property of transmitting various substances such as paper, plastic, vinyl, fiber, semiconductor, and powder like radio waves. It also has the property of being reflected or condensed by a mirror or lens like light.

  As shown in FIG. 1, when a surface of a substrate 10 having a certain thickness is irradiated with a terahertz wave from the irradiation source 1, a part of the irradiation wave 11 is reflected by the substrate surface to become a reflected wave 12, and a part thereof Becomes the transmitted wave 13, but the remaining part is multiple-reflected on the back surface or the front surface of the substrate 10 to become the reflected wave 14 and the transmitted wave 15 as shown in the figure. Since the reflected wave 14 from the back surface of the base material 10 reciprocates inside the base material 10, the optical path becomes longer than the reflected wave 12 from the surface of the base material 10 by an amount corresponding to the thickness. There is a phase difference between 12 and the reflected wave 14. Two types of terahertz waves having a phase difference interfere with each other, and the interference waveform varies depending on the thickness of the substrate 10 and the frequency of the terahertz wave. The same applies to the transmitted wave 13 and the transmitted wave 15, and an interference waveform that varies depending on the thickness of the substrate 10 is obtained.

  This principle has been used for interference film thickness meters in the past. Usually, a sensor is installed on the irradiation side and a reflected wave is used. However, since terahertz waves easily pass through the substrate 10, as shown in FIG. The transmitted wave can be detected by installing the sensor 2 on the side opposite to the irradiation side where the irradiation source 1 is located. FIG. 2 is a graph of an interference waveform obtained by frequency analysis of the detected transmitted wave, where the vertical axis represents the transmittance and the horizontal axis represents the frequency. The frequency interval X changes according to the thickness of the substrate 10. The wave height Y represents the strength of interference due to the phase difference.

  In order to obtain a clear interference waveform, it is preferable to use a terahertz wave whose wavelength is about 1/2 to 1/10 of the thickness of the base material 10. For example, when the thickness of the base material is 1.5 mm The terahertz wave having a wavelength of 0.45 mm (frequency is 1.5 THz) is suitable. In order to obtain a clear interference waveform, it is preferable to use a single wavelength terahertz wave.

  The identification tag of the present invention has a flat plate structure in which a plurality of regions having different thicknesses are combined, detects the thickness of each region using terahertz waves, and determines authenticity. This will be specifically described below.

  FIG. 3 is a schematic diagram of the identification tag of the present invention. Here, in order to simplify the description, identification tags divided into four areas (1), (2), (3), and (4) are shown. These four regions have different thicknesses, and are processed into two types of thicknesses of 1 mm and 1.5 mm, for example. These thicknesses are for convenience of the following description.

  In the identification tag shown in FIG. 3, the thicknesses of the upper left (1) and lower left (3) regions are 1.5 mm, and the upper right (2) and lower right (4) regions are 1 mm thick. ing. When the region (1) and (3) are irradiated with terahertz waves of frequencies A, B, C, and D that have the maximum transmittance when the thickness of the identification tag is 1.5 mm, the obtained data graph is obtained. As shown by the solid line in FIG. 4, the waveform 1 data peculiar to the regions (1) and (3) where the transmittance is maximum at the frequencies A, B, C, and D are obtained. Next, when the regions (2) and (4) having a film thickness of 1 mm are irradiated with terahertz waves having the frequencies A, B, C, and D, the transmittance is maximized at the frequencies A and C as indicated by broken lines in FIG. Waveform data 2 peculiar to the areas (2) and (4) is obtained. In this description, the thickness difference between the regions is set to 0.5 mm. However, in practice, the thickness difference is further reduced, or three or more types of thickness are provided to increase the forgery prevention effect. Is preferred.

As described above, in the present invention, a terahertz wave having a different frequency is irradiated to an identification tag in which a plurality of regions having different thicknesses are combined, and the detected terahertz wave is converted into waveform data representing transmittance for each frequency.
The waveform data in the present invention is merely a graph obtained by connecting discrete data in which the transmittance with respect to an arbitrary frequency is plotted, and the waveform data includes the discrete data itself.

  FIG. 5 schematically shows such a state. Then, if the detected waveform is compared with reference waveform data stored in advance, the authenticity of the identification tag can be determined. The irradiation position can be freely moved by reflecting the terahertz wave using a mirror, and it is preferable to sequentially irradiate each region.

  The difficulty of forgery can be increased by increasing the number of regions formed in the above identification tag. However, as described above, it is difficult to economically manufacture an identification tag having an increased number of regions by a method of bonding blocks or a method using a mold. On the other hand, in the present invention, as shown below, an identification tag can be economically manufactured by applying a seal stamp manufacturing technique.

  That is, in the manufacturing method according to the present invention, first, a block pattern having a complicated combination of a plurality of regions is created. Then, a thermal head is pressed against the plate-like base material 10 made of a thermoplastic material capable of reflecting or transmitting the terahertz wave as shown in the block. The thermal head includes a large number of heating elements arranged in a straight line, and its position, pressing pressure, time, amount of heat, and the like are controlled by a computer. The heat control data of the heating elements is created according to the image data created by the typesetting software, and a plurality of regions having different thicknesses can be formed on the base material 10 based on the data. Note that a printing surface forming technique using a thermal head is described in Japanese Patent No. 6205731 of the present applicant.

  If the manufacturing method described above is used, an identification tag having a large number of regions having different thicknesses can be manufactured economically. As the material 10, a thermoplastic material that can be easily processed using a thermal head is used. Specific examples include polyethylene, polypropylene, polybutylene, polyvinyl chloride, and polyester. From the viewpoint of workability with a thermal head, it is more preferable to use a porous material.

  The identification tag of the present invention is suitable for use as a product tag or the like. If the terahertz wave is used, a very small difference in thickness can be accurately detected, so that the difference in thickness in each region can also be made extremely small. It is extremely difficult to break down the pattern and decipher the pattern. As described above, since the terahertz wave can pass through various substances, there is an advantage that it can be used even when the identification tag of the present invention is sealed inside.

DESCRIPTION OF SYMBOLS 1 Irradiation source 2 Sensor 10 Base material 11 Irradiation wave 12 Reflected wave 13 Transmitted wave 14 Reflected wave 15 Transmitted wave

Claims (5)

  An identification tag comprising a flat plate structure made of a thermoplastic material capable of reflecting or transmitting terahertz waves and combining a plurality of regions having different thicknesses.   The identification tag according to claim 1, wherein the thermoplastic material is a porous material. A step of creating a pattern composition combining a plurality of areas;
A step of pressing a thermal head on the plate-like body made of a thermoplastic material capable of reflecting or transmitting a terahertz wave, as in the above-mentioned plate, and
A method of manufacturing an identification tag, wherein a plurality of regions having different thicknesses are formed by controlling at least one of pressure, time, and amount of heat for pressing the thermal head for each region. The identification tag according to claim 1 or 2 is irradiated with terahertz waves having different frequencies,
Terahertz waves that are reflected or transmitted on the front surface and the back surface of the identification tag and interfere due to an optical path difference are detected from the irradiation side of the identification tag or the back surface side thereof,
A method for detecting an interference waveform of an identification tag, comprising: converting a detected terahertz wave into waveform data representing transmittance for each frequency.   An identification tag authenticity determination method, wherein the authenticity of an identification tag is determined by comparing the waveform data obtained by the waveform detection method according to claim 4 with reference waveform data stored in advance.

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