RFID Tag and Antenna Member Used Therein

Abstract

To provide an RFID tag that achieves reduction in cost while comprising an antenna with an isotropic radiation pattern.SOLUTION: An RFID tag 10 comprises a base material 22, an antenna part 24, and an IC chip 30. A split-ring resonance part 40 of the antenna part 24 has a first portion 42 and a second portion 44. A first end part 421 of the first portion 42 is provided with a first opposed part, and a first end part 423 thereof is provided with a first connection part. A second end part 441 of the second portion 44 is provided with a second opposed part, and a second end part 443 thereof is provided with a second connection part. The first opposed part 421 and the second opposed part 441 are separated from and opposed to each other. A third end part 501 of an impedance matching part 50 is connected with the first portion 42 at a part between the first opposed part 421 and the first connection part 423, and a third end part 503 thereof is connected with the second portion 44 at a part between the second opposed part 441 and the second connection part 443. The IC chip 30 is connected with the first connection part 423 and the second connection part 443.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an RFID (Radio Frequency Identification) tag and an antenna member used therefor.

Background Art

[0002] An RFID tag is an information storage medium that can write and read information non - contactlessly using a reader / writer. The RFID tag is provided with an antenna for wireless communication with the reader / writer. In order to enable reading and writing from the reader / writer at a distance of about several meters from the RFID tag regardless of the position and orientation of the RFID tag, the antenna of the RFID tag is required to have an isotropic radiation pattern.

[0003] Patent Document 1 discloses an example of a non - contact communication medium (RFID tag). As shown in FIG. 3, the non - contact communication medium 90 of Patent Document 1 includes two dipole antennas 92, 94 and an IC chip 96. The dipole antennas 92, 94 each have two radiating elements 920 or 940 and are arranged so as to be orthogonal to each other. The IC chip 96 is arranged at the intersection of the dipole antennas 92, 94. With this configuration, the combined radiation pattern of the dipole antennas 92, 94 has substantially isotropy.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the contactless communication medium 90 of Patent Document 1, the IC chip 96 is connected to two dipole antennas 92 and 94. The IC chip 96 connected to a plurality of antennas in this way is more expensive than an IC chip connected to a single antenna. Therefore, the contactless communication medium 90 of Patent Document 1 has the problem of high cost.

[0006] An object of the present invention is to provide an RFID tag that includes an antenna having an isotropic radiation pattern and can achieve cost reduction.

[0007] Another object of the present invention is to provide an antenna member including an antenna having an isotropic radiation pattern that enables cost reduction of an RFID tag.

Means for Solving the Problems

[0008] The present invention provides, as a first RFID tag, an RFID tag including an insulating base material, an antenna portion formed on the base material, and an IC chip, wherein the antenna portion has a split ring resonance portion and an impedance matching portion, the split ring resonance portion has a first portion and a second portion, the first portion has two first ends, a first opposing portion is provided at one of the first ends, and a first connection portion is provided at the other of the first ends, the second portion has two second ends, a second opposing portion is provided at one of the second ends, and a second connection portion is provided at the other of the second ends, the first opposing portion and the second opposing portion face each other with a gap therebetween, the impedance matching portion has two third ends, one of the third ends is connected to the first portion between the first opposing portion and the first connection portion, The other remaining part of the third end portion is connected to the second portion between the second opposing portion and the second connecting portion. The IC chip is connected to the first connecting portion and the second connecting portion. It provides an RFID tag.

[0009] Further, the present invention provides, as a second RFID tag, a first RFID tag, The split ring resonance portion has two sides extending in a first horizontal direction and two sides extending in a second horizontal direction orthogonal to the first horizontal direction. It provides an RFID tag.

[0010] Further, the present invention provides, as a third RFID tag, a second RFID tag, The widths of the first portion and the second portion are both wider than the width of the impedance matching portion. It provides an RFID tag.

[0011] Further, the present invention provides, as a fourth RFID tag, a second or third RFID tag, The first connecting portion and the second connecting portion are located on the side extending in the first horizontal direction, The size of the first connecting portion and the second connecting portion in the second horizontal direction is larger than the size of the IC chip in the second horizontal direction. It provides an RFID tag.

[0012] Further, the present invention provides, as a fifth RFID tag, any one of the first to fourth RFID tags, The antenna portion has a single-layer structure. It provides an RFID tag.

[0013] Furthermore, the present invention provides, as a first antenna member, an antenna member for an RFID tag including an insulating base material and an antenna portion formed on the base material, The antenna portion has a split ring resonance portion and an impedance matching portion. The split-ring resonance part has a first part and a second part, The first part has two first ends, A first opposing part is provided at one of the first ends, and a first connecting part is provided at the other of the first ends, The second part has two second ends, A second opposing part is provided at one of the second ends, and a second connecting part is provided at the other of the second ends, The first opposing part and the second opposing part face each other with a gap therebetween, The impedance matching part has two third ends, One of the third ends is connected to the first part between the first opposing part and the first connecting part, The other of the third ends is connected to the second part between the second opposing part and the second connecting part, The first connecting part and the second connecting part are arranged in the vicinity of each other with a gap therebetween. An antenna member is provided.

Advantages of the Invention

[0014] The RFID tag of the present invention includes an antenna part having a split-ring resonance part and an impedance matching part. The radiation pattern of this antenna part has isotropy equivalent to the radiation pattern realized by two dipole antennas arranged orthogonally to each other. That is, the RFID tag of the present invention can realize an isotropic radiation pattern with a single antenna. Therefore, the RFID tag of the present invention can use an inexpensive IC chip, and cost reduction can be achieved.

[0015] Also, since the antenna part of the antenna member of the present invention can realize an isotropic radiation pattern with a single antenna, it enables the use of an inexpensive IC chip and enables the provision of an inexpensive RFID tag.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0017] (First Embodiment) Referring to FIG. 1, an RFID (Radio Frequency Identification) tag 10 according to a first embodiment of the present invention includes an antenna member 20 and an IC chip 30. The antenna member 20 includes a base material 22 and an antenna portion 24 formed on the base material 22. The base material 22 is made of an insulating material. The base material 22 may be, for example, an insulating film. The antenna portion 24 has a split ring resonance portion 40 and an impedance matching portion 50. The antenna portion 24 is made of a conductor, for example, an aluminum film or a conductive ink. In the present embodiment, the antenna portion 24 has a single-layer structure composed of a single conductor layer. However, the present invention is not limited to this. The antenna portion 24 may have a multilayer structure composed of a plurality of conductive layers.

[0018] As shown in FIG. 1, the split ring resonance portion 40 has a first portion 42 and a second portion 44. The first portion 42 and the second portion 44 are formed and arranged such that the outer shape of the split ring resonance portion 40 is substantially rectangular. Thereby, the split ring resonance portion 40 has two sides 401 and 405 extending in a first horizontal direction, and two sides 403 and 407 extending in a second horizontal direction orthogonal to the first horizontal direction. In the present embodiment, the first horizontal direction is the X direction, and the second horizontal direction is the Y direction. Hereinafter, for convenience of explanation, the four sides 401, 403, 405, and 407 of the split ring resonance portion 40 are referred to as the first side 401, the second side 403, the third side 405, and the fourth side 407 in a clockwise direction.

[0019] As shown in FIG. 1, the first part 42 has two first ends 421 and 423, and the second part 44 has two second ends 441 and 443. In the present embodiment, the first part 42 and the second part 44 have shapes that are line-symmetric to each other and are arranged to be mirror images of each other. However, the present invention is not limited thereto. The first part 42 and the second part 44 only need to be configured and arranged to function as a split-ring resonator, and do not necessarily have shapes that are line-symmetric to each other.

[0020] As shown in FIG. 1, one of the first ends 421 and 423 faces the other of the second ends 441 and 443 with a gap therebetween. In other words, a first facing portion (421) is provided on one of the first ends 421 and 423, and a second facing portion (441) is provided on one of the second ends 441 and 443. In the present embodiment, the first facing portion 421 is provided on the first end 421, and the second facing portion 441 is provided on the second end 441. The first facing portion 421 and the second facing portion 441 face each other with a gap therebetween and constitute a capacitor.

[0021] As shown in FIG. 1, the other of the first ends 421 and 423 and the other of the second ends 441 and 443 are arranged close to each other with a gap therebetween. An IC chip 30 is connected to the other of the first ends 421 and 423 and the other of the second ends 441 and 443. In other words, a first connection portion (423) is provided on the other of the first ends 421 and 423, and a second connection portion (443) is provided on the other of the second ends 441 and 443. In the present embodiment, the first connection portion 423 is provided on the first end 423, and the second connection portion 443 is provided on the second end 443. The IC chip 30 is connected to the first connection portion 423 and the second connection portion 443.

[0022] As shown in Fig. 1, the impedance matching section 50 is connected to the first part 42 and the second part 44 of the split ring resonance section 40. Specifically, the impedance matching section 50 has two third ends 501 and 503. One of the third ends 501 and 503 is connected to the first part 42 between the first opposing part 421 and the first connection part 423. The other of the third ends 501 and 503 is connected to the second part 44 between the second opposing part 441 and the second connection part 443. In the present embodiment, the third end 501 is connected to the first part 42 on the second side 403 of the split ring resonance section 40. The third end 503 is connected to the second part 44 on the fourth side 407 of the split ring resonance section 40. However, the present invention is not limited thereto. The impedance matching section 50 only needs to be connected to the first part 42 and the second part 44 of the split ring resonance section 40, and the connection position and the shape thereof are not particularly limited. For example, the third ends 501 and 503 of the impedance matching section 50 may be respectively connected to the first part 42 and the second part 44 on the third side 405 of the split ring resonance section 40. In that case, the shape of the impedance matching section 50 may be an angular C shape. Further, the shape may be such that a widened portion is partially formed so that the third ends 501 and 503 respectively reach the second side 403 and the fourth side 407 of the split ring resonance section 40. Note that the connection position and the shape of the impedance matching section 50 can be arbitrarily set according to the required impedance characteristics.

[0023] As understood from Fig. 1, the widths of the first part 42 and the second part 44 are both wider than the width of the impedance matching section 50. Here, the "width" is the size of each part in the direction orthogonal to the extending direction in the first part 42, the second part 44, and the impedance matching section 50 respectively. In the present embodiment, the first part 42 has four widths W 1-1 ~W 1-4 and the second part 44 also has four widths W 2-1 ~W 2-4 The impedance matching section 50 has a single width W3 (<W 1-1 ~W 1-4 ,W 2-1~W 2-4 ) has it. However, the present invention is not limited thereto. Each of the first part 42 and the second part 44 may have a single width. Or, each of the first part 42 and the second part 44 may have two widths, where the width of the first end 421 and its periphery is wide and the width of the other parts is narrow. Further, the impedance matching part 50 may have a plurality of different widths.

[0024] As understood from FIG. 1, the IC chip 30 is mounted on the surface of the base material 22 and connected to the first connection part 423 and the second connection part 443. In the present embodiment, the first connection part 423 and the second connection part 443 are located on the third side 405 extending in the first horizontal direction. And the sizes (widths W 1-4 , W 2-4 equal to) in the second horizontal direction (Y direction) of the first connection part 423 and the second connection part 443 are both larger than the size Wc of the IC chip 30 in the second horizontal direction (Wc < W 1-4 , W 2-4 ).

[0025] As shown in FIG. 1, the IC chip 30 of the present embodiment is located at the center of the first connection part 423 and the second connection part 443 in the second horizontal direction. However, the present invention is not limited thereto. The IC chip 30 may be connected to the first connection part 423 and the second connection part 443 at a position closer to the inside or outside of the split ring resonance part 40.

[0026] In the RFID tag 10 of the present embodiment, the antenna part 24 can realize an isotropic radiation pattern alone. Therefore, an inexpensive IC chip can be used as the IC chip 30 of the RFID tag 10.

[0027] (Second Embodiment) Referring to FIG. 2, the RFID tag 10A according to the second embodiment of the present invention has first and second portions 42A and 44A having shapes different from those of the first and second portions 42 and 44 of the split ring resonance portion 40 in the RFID tag 10 of the first embodiment. For other components, since they are the same as or similar to the components of the RFID tag 10, the same reference numerals are given and the description thereof is omitted.

[0028] As shown in FIG. 2, the first portion 42A and the second portion 44A of the split ring resonance portion 40 are formed and arranged such that the outer shape of the split ring resonance portion 40 is substantially rectangular. The first end 421 of the first portion 42A and the second end 441 of the second portion 44A are located on the first side 401 of the split ring resonance portion 40. Also, the first end 423 of the first portion 42A and the second end 443 of the second portion 44A are located on the fourth side 407 of the split ring resonance portion 40.

[0029] As shown in FIG. 2, the impedance matching portion 50 is connected to the first portion 42A and the second portion 44A of the split ring resonance portion 40. The third end 501 of the impedance matching portion 50 is connected to the first portion 42A between the first opposing portion 421 and the first connecting portion 423. Also, the third end 503 is connected to the second portion 44A between the second opposing portion 441 and the second connecting portion 443. In the present embodiment, the third end 501 is connected to the first portion 42A on the third side 405 of the split ring resonance portion 40, and the third end 503 is connected to the second portion 44A on the first side 401 of the split ring resonance portion 40. However, the present invention is not limited thereto. The impedance matching portion 50 only needs to be connected to the first portion 42A and the second portion 44A as long as it is connected to them, and the connection position and its shape are not particularly limited. For example, the third ends 501, 503 of the impedance matching portion 50 are on the fourth side 407 of the split ring resonance portion 40 at the first portion 42A and the second portion 44Amay be respectively connected thereto. In that case, the shape of the impedance matching unit 50 may be an angular C shape. Further, the shape may be such that wide portions are partially formed so that the third ends 501 and 503 reach the third side 405 and the first side 401 of the split ring resonator 40, respectively.

[0030] As understood from FIG. 2, also in this embodiment, the widths of both the first portion 42A and the second portion 44A are wider than the width of the impedance matching unit 50. Further, the sizes of both the first connection portion 423 and the second connection portion 443 in the first horizontal direction (X direction) are larger than the size of the IC chip 30 in the first horizontal direction.

[0031] Also in the RFID tag 10A of this embodiment, the antenna portion 24 can realize an isotropic radiation pattern alone. Therefore, an inexpensive IC chip can be used as the IC chip 30 of the RFID tag 10A.

[0032] As described above, the present invention has been described with reference to embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications and changes are possible without departing from the gist of the present invention. For example, in the antenna portion 24, the width of each portion, the positions of the first opposing portion 421 and the second opposing portion 441, and the positions of the first connection portion 423 and the second connection portion 443 can be arbitrarily set according to the required antenna characteristics.

Explanation of Reference Numerals

[0033] 10 ,10A RFID tag 20 Antenna member 22 Base material 24 Antenna portion 30 IC chip 40 Split ring resonator 401 Side (first side) 403 Side (second side) 405 Side (third side) 407 Side (fourth side) 42 ,42A First portion 421 First end portion (first opposing portion) 423 First end portion (first connection portion) 44 ,44A Second part 441 Second end portion (second opposing portion) 443 Second end portion (second connection portion) 50 Impedance matching section 501, 503 Third end portion

Claims

1. An RFID tag comprising an insulating substrate, an antenna portion formed on the substrate, and an IC chip, wherein the antenna portion has a split ring resonance portion and an impedance matching portion, the split ring resonance portion has a first portion and a second portion, the first portion has two first ends, a first opposing portion is provided at one of the first ends, and a first connection portion is provided at the other of the first ends, the second portion has two second ends, a second opposing portion is provided at one of the second ends, and a second connection portion is provided at the other of the second ends, the first opposing portion and the second opposing portion face each other with a gap therebetween, the impedance matching portion has two third ends, one of the third ends is connected to the first portion between the first opposing portion and the first connection portion, the other of the third ends is connected to the second portion between the second opposing portion and the second connection portion, the IC chip is connected to the first connection portion and the second connection portion RFID tag.

2. The RFID tag according to claim 1, wherein the split ring resonance portion has two sides extending in a first horizontal direction and two sides extending in a second horizontal direction orthogonal to the first horizontal direction RFID tag.

3. The RFID tag according to claim 2, wherein the widths of the first portion and the second portion are both wider than the width of the impedance matching portion RFID tag.

4. The RFID tag according to claim 2 or claim 3, wherein the first connection portion and the second connection portion are located on the side extending in the first horizontal direction, the sizes of the first connection portion and the second connection portion in the second horizontal direction are larger than the size of the IC chip in the second horizontal direction RFID tag.

5. The RFID tag according to any one of claims 1 to 4, wherein the antenna portion has a single-layer structure RFID tag.

6. An antenna member for an RFID tag comprising an insulating substrate and an antenna portion formed on the substrate, wherein the antenna portion has a split ring resonance portion and an impedance matching portion, the split ring resonance portion has a first portion and a second portion, the first portion has two first ends, One side of the first end portion is provided with a first opposing portion, and the other side of the remaining part of the first end portion is provided with a first connection portion. The second part has two second end portions. One side of the second end portion is provided with a second opposing portion, and the other side of the remaining part of the second end portion is provided with a second connection portion. The first opposing portion and the second opposing portion face each other with a gap therebetween. The impedance matching portion has two third end portions. One of the third end portions is connected to the first part between the first opposing portion and the first connection portion. The other of the third end portions is connected to the second part between the second opposing portion and the second connection portion. The first connection portion and the second connection portion are arranged in the vicinity of each other with a gap therebetween. Antenna member.

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