Name of invention: IC tag
Technical field
[0001]
　The present invention relates to IC tags.
Background technology
[0002]
　In recent years, as one type of IC tag, a configuration in which an antenna pattern for radio wave communication and an IC chip are mounted on a base sheet made of plastic or paper called an inlet has been proposed. Then, such an inlet is used for management of an article by attaching the one sealed with resin to the article or embedding it in the article.
[0003]
　By the way, the IC tag as described above may be attached to a linen article and managed, but the linen article is generally inspected for contamination with a metal foreign substance by a metal detector at the time of shipment. On the other hand, since the antenna pattern of the IC tag is made of metal, when the linen article to which the IC tag is attached is inspected with a metal detector, the IC tag is not affected by foreign metal. Will be detected as metal. Therefore, there is a problem that the original inspection of metallic foreign substances cannot be performed smoothly.
[0004]
　On the other hand, Patent Document 1 discloses an IC tag having a resistance value of an antenna of 50 to 1000Ω, and an IC tag having a resistance value in such a range may not react to a metal detector. It is disclosed.
Prior art documents
Patent documents
[0005]
Patent Document 1: Japanese Unexamined Patent Publication No. 2016-33748
Summary of the invention
Problems to be Solved by the Invention
[0006]
　However, even the IC tag of Patent Document 1 may be detected by a metal detector, and further improvement has been desired. The present invention has been made to solve the above problems, and an object of the present invention is to provide an IC tag that can more reliably prevent detection by a metal detector.
Means for solving the problems
[0007]
　The IC tag according to the present invention includes an IC chip, a dipole antenna that electrically transmits and receives information stored in the IC chip, and a sheet-shaped base material that supports the IC chip and the dipole antenna. When a resistance value R between both ends of the dipole antenna and a length L of a path connecting the both ends of the dipole antenna along the dipole antenna and not passing through the IC chip are set. , 0.1 ≦ R / L ≦ 2.5 is satisfied.
[0008]
　In the above IC tag, the length L can be 120 mm or more and 200 mm or less.
[0009]
　In each of the above IC tags, the material constituting the dipole antenna can contain any of silver, aluminum, and copper.
[0010]
　Each of the IC tags may further include a sheet-shaped cover that covers the IC chip and the antenna between the base material and an adhesive that adheres the cover and the base material.
Effect of the invention
[0011]
　According to the present invention, detection by a metal detector can be prevented more reliably.
A brief description of the drawing
[0012]
FIG. 1 is a plan view showing an embodiment of an IC tag according to the present invention.
FIG. 2 is a cross-sectional view of the IC tag of FIG.
3 is a plan view illustrating the antenna of the IC tag of FIG. 1. FIG.
FIG. 4 is a plan view showing the shapes of dipole antennas used in Example 1 and Comparative Example 1.
FIG. 5 is a plan view showing the shape of a dipole antenna used in Example 2.
FIG. 6 is a plan view showing the shape of the dipole antenna used in Example 3 and Comparative Example 2.
FIG. 7 is a plan view showing the shape of the dipole antenna used in the fourth embodiment.
FIG. 8 is a plan view showing the shape of a dipole antenna used in Example 5.
MODE FOR CARRYING OUT THE INVENTION
[0013]
　<1. Outline of IC Tag>
　Hereinafter, an embodiment of an IC tag according to the present invention will be described with reference to the drawings. FIG. 1 is a plan view of an IC tag according to this embodiment, and FIG. 2 is a sectional view of FIG. However, the cover is omitted in FIG. 1 for convenience of description. As shown in FIGS. 1 and 2, the IC tag according to this embodiment includes a sheet-shaped base material 1 formed in a rectangular shape, an IC chip 2 and a dipole antenna 3 arranged on the base material 1. And a sheet-like cover 4 formed in a rectangular shape to cover the IC chip 2 and the dipole antenna 3. The base material 1 and the cover 4 are adhered to each other by the adhesive 5. Hereinafter, each of these members will be described in detail.
[0014]
　The base material 1 and the cover 4 are formed in the same shape, and the adhesive 5 is arranged over the entire surface between them. That is, the IC chip 2 and the dipole antenna 3 are covered with the adhesive 5, so that the IC chip 2 and the dipole antenna 3 are not exposed from the gap between the base material 1 and the cover 4.
[0015]
　Materials forming the base material 1 and the cover 4 are not particularly limited, but may be formed of, for example, polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, or the like. The thickness of the base material 1 and the cover 4 is, for example, preferably 25 to 200 μm, and more preferably 25 to 100 μm.
[0016]
　Further, for convenience of description, the sides of the base material 1 and the cover 4 in the longitudinal direction are referred to as a first side 101 and a second side 102, and the sides in the lateral direction are referred to as a third side, for convenience of description below. It will be referred to as side 103 and fourth side 104. Therefore, these sides are connected in the order of the first side 101, the third side 103, the second side 102, and the fourth side 104.
[0017]
　The IC chip 2 is a known one having a memory function, and is electrically connected to the dipole antenna 3 formed of a conductor.
[0018]
　In this embodiment, as an example, a dipole antenna as shown in FIG. 1 is used. That is, the dipole antenna 3 includes an impedance matching portion 31 arranged near the center of the base material 1 in the longitudinal direction, and a pair of dipole portions 32 extending from the impedance matching portion 31 in the longitudinal direction of the base material 1. ing. The impedance matching portion 31 is formed in a rectangular frame shape having first to fourth sides. More specifically, the first side 311 of the impedance matching section 31 is arranged at a position slightly apart from the first side 101 of the base material 1, and the second side 312 is arranged along the second side 102 of the base material 1. It is arranged. That is, in the impedance matching unit 31, the first side 311, the third side 313, the second side 312, and the fourth side 314 are connected in this order. The IC chip 2 is arranged near the center of the first side 311 of the impedance matching section 31.
[0019]
　Since the dipole portion 32 has a symmetrical shape, only one of the dipole portions 32 will be described. The dipole portion 32 extends from the first side 311 of the impedance matching portion 31 to the first side 101 side of the base material 1, and from there to the first side 101, the third side 103, and the second side 102 of the base material 1. A rectangular frame is formed so as to extend along the third side 313 of the impedance matching portion 31, and then extends spirally inside the frame.
[0020]
　The material forming the dipole antenna 3 is not particularly limited, but it can be formed of, for example, silver, copper, or aluminum. When silver is used, the dipole antenna 3 can be formed by applying a silver paste containing silver onto the base material 1 by screen printing. On the other hand, when copper or aluminum is used, the dipole antenna 3 can be formed by etching. Further, the IC chip 2 can be fixed to the antenna 3 by, for example, known flip-chip mounting for electronic parts.
[0021]
　With the dipole antenna 3 as described above, for example, information stored in the IC chip 2 can be transmitted and received by radio waves in the UHF band.
[0022]
　The adhesive 5 can be, for example, a rubber-based adhesive containing natural rubber or synthetic rubber as a main component. The thickness of the rubber-based pressure-sensitive adhesive 5 is not particularly limited, but is preferably 28 to 500 μm, and more preferably 28 to 72 μm. The synthetic rubber used for the rubber-based pressure-sensitive adhesive 5 is not particularly limited, and examples thereof include styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, and hydrogenation of the styrene-based block copolymer. Examples thereof include styrene-butadiene rubber (SBR), polyisobutylene rubber (IR), polyisobutylene (PIB), and butyl rubber (IIR).
[0023]
　Further, in addition to the above-mentioned natural rubber and synthetic rubber, the rubber-based pressure-sensitive adhesive 5 may contain a pressure-sensitive adhesive. Examples of the tackifier include terpene phenol resin, rosin resin, petroleum resin and the like. The amount of the tackifying resin used can be appropriately selected within a range that does not impair the adhesive performance. Further, the rubber-based pressure-sensitive adhesive may contain appropriate additives such as a softener, a plasticizer, a filler, an antiaging agent, and a colorant, if necessary, in addition to the above-mentioned components.
[0024]
　As the pressure-sensitive adhesive 5, an acrylic-based or silicone-based pressure-sensitive adhesive may be used in addition to the rubber-based pressure-sensitive adhesive.
[0025]
　<2. Physical properties and electrical characteristics of the dipole antenna>
　The dipole antenna 3 according to the present embodiment has the following physical properties and electrical characteristics. This point will be described with reference to FIG. As shown in the figure, first, the resistance value R (Ω) between the ends S1 and S2 of the dipole antenna 3 and the length of the path connecting the ends S1 and S2 of the dipole antenna 3 along the dipole antenna 3 are shown. Now, when the length L (cm) of the path that does not pass through the IC chip 2 (hereinafter referred to as the antenna path: the broken line in FIG. 3) is set, the dipole antenna 3 according to the present embodiment is Satisfy 1). The antenna path is a path that passes through the center of the line width of the dipole antenna 1.
　0.1 ≤ R / L ≤ 2.5 (1)
[0026]
　As a result, the resistance per unit length of the antenna path is set, but if the R / L is 0.1 or more, it becomes difficult for the current to flow, so that the resistance is prevented from being detected by the metal detector. On the other hand, if the R / L is larger than 2.5, the communication distance may be shortened and the target application may be limited. Therefore, the R / L is preferably 2.5 or less. In order to further prevent detection by the metal detector, it is more preferable that the R / L satisfies the following equation (2).
　1.5≦R/L≦2.5 (2)
[0027]
　The resistance value R (Ω) between both ends S1 and S2 of the antenna 3 is not particularly limited, but is preferably, for example, 10 to 50 Ω, and more preferably 20 to 44 Ω. This is because if the resistance value R is 10 Ω or more, it becomes difficult for the current to flow, and if it is 50 Ω or less, the communication distance becomes long and the communication becomes stable.
[0028]
　The length L of the antenna path described above is also not particularly limited, but is preferably 120 to 200 mm, preferably 130 to 180 mm, for example. This is because if the length L of the antenna path is short, communication becomes unstable, and if the antenna path is too long, it is likely to be detected by the metal detector.
[0029]
　The size of the outer shape of the dipole antenna 3 is not particularly limited, but in order to prevent detection by a metal detector, for example, the length X of the outer shape of the dipole antenna 3 in the longitudinal direction may be 60 mm or less. It is preferably 40 mm or less. Further, the length Y of the outer shape of the dipole antenna 3 in the lateral direction is preferably 20 mm or less, and more preferably 10 mm or less. Therefore, the outer area (X*Y) of the dipole antenna is preferably 1200 mm 2 , and more preferably 400 mm 2 or less.
[0030]
　The thickness of the dipole antenna 3 is not particularly limited, but is preferably 20 μm or less, more preferably 15 μm or less, and particularly preferably 10 μm or less. For example, when the dipole antenna 3 is formed by printing using the silver paste described above, it becomes easier to adjust the thickness of the dipole antenna 3 than when the dipole antenna 3 is formed by etching using copper or aluminum, and the thickness is 10 μm or less. It can be thick. This makes it possible to further prevent detection by the metal detector.
[0031]
　<3. Metal detector>
　The metal detector that assumes that the IC tag according to this embodiment is not detected can be, for example, a metal detector that detects non-ferrous metals. This is because the dipole antenna may be formed of a non-ferrous metal such as silver, copper, or aluminum as described above. The detection sensitivity is preferably not detected, for example, when MUK-500 manufactured by Nikka Densoku Co., Ltd. is used as a metal detector. This device has a detection sensitivity capable of detecting a SUS sphere having an outer diameter of 1.5 mm or more as the smallest substance that can be detected. Therefore, as an example, as a metal detector in which the IC tag according to the present embodiment is not detected, a metal detector having the above-mentioned detection sensitivity for non-ferrous metals can be defined. However, this is an example, and a metal detector that detects iron can be used as a reference.
[0032]
　<4. Features> As
　described above, according to the IC tag of the present embodiment, since the dipole antenna 3 is configured to satisfy the above expression (1), it is possible to prevent the dipole antenna 3 from being detected by the metal detector. You can
[0033]
　<5. Modifications>
　One embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit thereof. The plurality of modified examples shown below can be combined as appropriate.
[0034]
　<5-1>
　The shape of the dipole antenna 3 described above is an example, and various shapes can be made as long as the above formula (1) is satisfied. Further, the shape of the IC tag, that is, the shape of the base material 1 and the cover 4 is not particularly limited, and in addition to the long shape as described above, various shapes such as a rectangular shape, a circular shape, and a polygonal shape are used according to the application. Can be shaped. Further, the base material 1 and the cover 4 do not have to have the same shape.
[0035]
　<5-2> In the
　above embodiment, the adhesive 5 is applied over the entire surface between the base material 1 and the cover 4, but the present invention is not limited to this. For example, the rubber-based adhesive 5 may be applied only to the peripheral edges of the base material 1 and the cover 4 so that the IC chip 2 and the antenna 3 are surrounded by the adhesive 5. Further, the cover 4 and the adhesive 5 are not essential and may be omitted.
Example
[0036]
　Hereinafter, examples of the present invention will be described. However, the present invention is not limited to these examples.
[0037]
　<1. Preparation of Examples and Comparative Examples>
　IC tags according to Examples 1 to 5 and Comparative Examples 1 and 2 were prepared as follows. In these Examples and Comparative Examples, the base material and the IC chip are the same, but the dipole antennas are different. Here, five types of antenna shapes shown in FIGS. 4 to 8 were prepared, and three types of materials were prepared. The dotted line in FIGS. 4 to 8 is the path L, and the numerical values ​​indicate the lengths X and Y of the outer shape. Further, as a base material and a cover, a polyethylene terephthalate film having a thickness of 50 μm was prepared, a dipole antenna was placed between the base material and the cover, and fixed with the above-mentioned rubber-based adhesive. Then, the IC tags according to Examples 1 to 5 and Comparative Examples 1 and 2 were prepared as shown in Table 1 below. As shown below, the antennas of Examples and Comparative Examples are made of non-ferrous metal.
[table 1]

[0038]
　<2. Evaluation> As a
　metal detector, MUK-500 manufactured by Nikka Densoku Co., Ltd. was used, and it was tested whether the above Examples and Comparative Examples could be detected. The detection level in this device is 0-12. Specifically, it is as follows. That is, when a SUS304 sphere is used, this device cannot detect a sphere having a diameter of 1 mm, but can detect a sphere having a diameter of 2 mm or more. The detection level when a sphere with a diameter of 2 mm is detected is 8, and the detection level when a sphere with a diameter of 3 mm is detected is 12. On the other hand, when the detection level is 0, it means that the metal detector cannot detect at all. That is, the closer the detection level is to 0, the more difficult the metal detector can detect.
[Table 2]

[0039]
　In Examples 1 to 3, the R / L was 1.5 or more, and the detection level was 0 in each case. That is, it was not detected at all by the metal detector. Further, in Examples 4 and 5, the R/L was lower than that of Examples 1 to 3 and was 1 or less, but was 0.1 or more. The detection level by the metal detector was 3. That is, although it is slightly detected, it is at a level that can be used depending on the application. On the other hand, in Comparative Examples 1 and 2, R/L was lower than 0.1 and the detection level was 12. That is, it is a level that can be reliably detected by the metal detector. Therefore, it was found by the evaluation based on R/L that Examples 1 to 5 are superior to Comparative Examples 1 and 2.
Explanation of symbols
[0040]
　1 Base material
　2 IC chip
　3 Dipole antenna
　4 Cover
　5 Adhesive
The scope of the claims
[Claim 1]
　It includes an IC chip,
　a dipole antenna that electrically transmits and receives information stored in the
　IC chip, and a sheet-shaped base material that supports the IC chip and the dipole antenna,
and has
　resistance between both ends of the dipole antenna. When the value R and the length L of the path connecting both ends of the dipole antenna along the dipole antenna and not passing through the IC chip are set, 0.1 ≦ R / L. An IC tag that satisfies ≤2.5.
[Claim 2]
　The IC tag according to claim 1, wherein the length L is 120 mm or more and 200 mm or less.
[Claim 3]
　The IC tag according to claim 1 or 2, wherein the material constituting the dipole antenna contains any of silver, aluminum, and copper.
[Claim 4]
　The invention according to any one of claims 1 to 3, further
　comprising a sheet-shaped cover for covering the IC chip and the antenna, and an adhesive for adhering the cover and the base material between the base materials.
IC tag.