RFID tag

Abstract

To provide an RFID tag that can suppress a decrease in communication performance even when its tag size is reduced, and can improve versatility.SOLUTION: In an RFID tag 1, a first distance L1 from an IC chip 21 to both ends of a pair of rectangular conductors 23A, 23B in the tag longitudinal direction, a second distance L2 from the IC chip 21 to the tips of a pair of first strip portions 232A, 232C, and a third distance L3 from the IC chip 21 to the tips of a pair of second strip portions 232B, 232D are formed to have different lengths. At least one of the first distance L1, the second distance L2, and the third distance L3 is set to have an electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag 1, and the remaining distances are set to have an electrical length different from the electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag 1.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to RFID tags.

Background Art

[0002] A method is known in which an RFID (Radio Frequency Identification) tag is attached to an article to be managed, and information about the article is read and written to and from the tag, thereby enabling highly accurate and simple management of the article.

[0003] For example, Patent Document 1 describes a configuration in which an RFID tag is attached to a cover or the like during bookbinding and used for book management.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, when applying an RFID tag to article management, it is desirable to be able to reduce the tag size in order to improve versatility. However, when the tag size is reduced, the size of the inlay also becomes relatively small. As a result, the communication performance of the tag may decrease.

[0006] An object of the present disclosure is to provide an RFID tag that can suppress a decrease in communication performance even when the tag size is reduced and can improve versatility.

Means for Solving the Problems

[0007] An RFID tag according to one aspect of an embodiment of the present invention includes an IC chip in which identification information is recorded, a loop conductor formed in a circular shape and connected to the IC chip, and extending from both sides of the loop conductor in a first direction and formed in a rectangular shape. A pair of rectangular conductors, and in each of the pair of rectangular conductors, a pair of first protrusions protruding outward from the rectangular conductor in a second direction orthogonal to the first direction from one side in the second direction, and in each of the pair of rectangular conductors, a pair of second protrusions protruding outward from the rectangular conductor in the second direction from the other side in the second direction, and provided so as to protrude along the first direction from the pair of first protrusions toward the center side in the first direction and formed in a strip shape. A pair of first strip portions, and provided so as to protrude along the first direction from the pair of second protrusions toward the center side in the first direction and formed in a strip shape. A pair of second strip portions, the first distance from the IC chip to both ends of the pair of rectangular conductors in the first direction, the second distance from the IC chip to the tips of the pair of first strip portions, and the third distance from the IC chip to the tips of the pair of second strip portions are formed with different lengths, and at least one of the first distance, the second distance, and the third distance is set to an electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag, and the rest of the first distance, the second distance, and the third distance are set to electrical lengths different from the electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag.

[0008] According to this aspect, by providing the antenna pattern of the inlay as described above, a plurality of current paths having different lengths can be formed. As a result, it is possible to increase the variation in the operating frequency, so that even if the tag size is reduced, a decrease in communication performance can be suppressed and the versatility can be improved.

[0009] In the RFID tag according to another aspect of the embodiment of the present invention, the IC chip may be arranged at the center in the first direction and may be arranged offset to one side from the center in the second direction, and the lengths of the pair of first strip portions and the pair of second strip portions in the first direction may be the same.

[0010] According to this aspect, in the antenna pattern in which the IC chip is displaced from the center in the second direction to one side, the second distance and the third distance can be surely made to have different lengths, so that it is possible to surely increase the variation in the operating frequency.

[0011] In the RFID tag according to another aspect of the embodiment of the present invention, the IC chip may be disposed at the center in the first direction and the second direction, and the pair of first strip portions and the pair of second strip portions may be configured to have different lengths in the first direction.

[0012] According to this aspect, in the antenna pattern in which the IC chip is disposed at the center in the first direction and the second direction, the second distance and the third distance can be surely made to have different lengths, so that it is possible to surely increase the variation in the operating frequency.

Advantages of the Invention

[0013] According to the present disclosure, it is possible to provide an RFID tag that can suppress a decrease in communication performance even when the tag size is reduced and can improve versatility.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments will be described with reference to the accompanying drawings. For ease of understanding of the description, the same reference numerals are given to the same components in each drawing as much as possible, and duplicate descriptions are omitted.

[0016] [First Embodiment] The first embodiment will be described with reference to FIGS. 1 to 6.

[0017] In the following description, the X direction, Y direction, and Z direction are perpendicular to each other. The X direction is the longitudinal direction of each component of the RFID tag 1 such as the inlay 2. The Y direction is the short-side direction of each element of the RFID tag 1 such as the inlay 2. The Z direction is the stacking direction of each component of the RFID tag 1 such as the inlay 2. Also, hereinafter, for convenience of explanation, the positive direction side of the Z axis may be expressed as the front side or the upper side, and the negative direction side of the Z axis may be expressed as the back side or the lower side.

[0018] <Structure of RFID Tag 1> FIG. 1 is a cross-sectional view of the RFID tag 1 according to the first embodiment. FIG. 2 is a plan view of the RFID tag 1 shown in FIG. 1 viewed from above. In FIG. 2, only the elements related to the inlay 2 in FIG. 1 are shown. The RFID tag 1 is a substantially planar device that is attached to an object to be attached. As shown in FIGS. 1 and 2, the RFID tag 1 incorporates an inlay 2.

[0019] The object to be attached includes, for example, books 30 such as books and magazines as will be described later with reference to FIG. 4. Further, the object to be attached is not limited to the book 30, and may be an article that is mainly stacked and arranged in the vertical or horizontal direction during storage, an article formed by stacking a large amount of paper in the same manner as the book 30, or an article formed of a material containing moisture such as paper in the same manner as the book 30. Examples of such articles include cards such as trading cards, stationery such as clear files and notebooks, foods such as confectionery, newspapers, tickets, and vouchers.

[0020] The RFID tag 1 of the first embodiment has flexibility and is preferably attachable even when the surface of the adherend is curved. Even in a curved state, it can exhibit good communication performance, and the RFID tag 1 of the first embodiment can be used for identifying articles having a curved surface, thereby achieving diversification of applications. The RFID tag 1 of the first embodiment is formed in a rectangular shape with the X direction as the longitudinal direction (first direction) and the Y direction as the short-side direction (second direction orthogonal to the first direction) in a plan view as viewed from the Z direction as shown in FIG. 2.

[0021] The inlay 2 is a portion including elements related to the function of the RFID tag 1, and as shown in FIG. 2, has an IC chip 21 in which identification information is recorded, a loop conductor 22 connected to the IC chip 21, and a pair of rectangular conductors 23A and 23B. In the following description, the pair of rectangular conductors 23A and 23B may be collectively referred to as "rectangular conductor 23" and are marked as such in FIG. 1.

[0022] The inlay 2 has a loop conductor 22 and a rectangular conductor 23 formed by dry-laminating an aluminum sheet on a base material 24 such as a synthetic resin film made of polyethylene terephthalate, polypropylene, etc., and the IC chip 21 is mounted at a specified position.

[0023] In the RFID tag 1 of the first embodiment, the shape of the inlay 2, particularly the shape of the antenna pattern including the loop-shaped conductor 22 and the pair of rectangular conductors 23A and 23B, is formed in a rectangular shape with the X direction as the longitudinal direction (first direction) and the Y direction as the short-side direction (second direction) in a plan view seen from the Z direction, similar to the RFID tag 1, as shown in FIG. 2.

[0024] The IC chip 21 has an internal capacitance, and a matching circuit is configured by the inductance of the rectangular conductor 23 and the internal capacitance of the IC chip 21.

[0025] The loop-shaped conductor 22 has a loop-shaped (annular) conductive wiring pattern with one turn or less in a plan view seen from the Z direction. In the first embodiment, the loop-shaped conductor 22 may be formed in an annular shape having at least a pair of opposite side portions that extend in the short-side direction (Y direction) of the RFID tag 1 and are arranged to face both ends in the longitudinal direction (X direction). In the first embodiment, as shown in FIG. 2, the loop-shaped conductor 22 is formed in a rectangular annular shape having a pair of short-side portions 221A and 221B and a pair of long-side portions 222A and 222B. In this embodiment, the pair of short-side portions 221A and 221B function as the above-mentioned "pair of opposite side portions".

[0026] Also, in the first embodiment, the pair of long-side portions 222A and 222B function as a "pair of second opposite side portions" that extend in the longitudinal direction (X direction) and are arranged to face both ends in the short-side direction (Y direction). One of the pair of short-side portions 221A and 221B is arranged on the X negative direction side (the left side in FIG. 2), and the other short-side portion 221B is arranged on the X positive direction side (the right side in FIG. 2). One of the pair of long-side portions 222A and 222B is arranged on the Y positive direction side (the upper side in FIG. 2), and the other long-side portion 222B is arranged on the Y negative direction side (the lower side in FIG. 2).

[0027] The loop-shaped conductor 22 is electrically connected to the IC chip 21 and the rectangular conductor 23. When the identification information recorded on the IC chip 21 is read by an RFID reader 40 (see FIG. 5 etc.), when the rectangular conductor 23 of the inlay 2 receives radio waves in the UHF band, for example, radio waves around 920 MHz, a current flows through the loop-shaped conductor 22 due to the resonance effect. Thereby, an electromotive force for operating the IC chip 21 is generated. When the IC chip 21 operates, the identification information recorded on the IC chip 21 is encoded by the IC chip 21, and the encoded data is wirelessly transmitted to a communication device such as the RFID reader 40 using radio waves around 920 MHz as a carrier wave. The RFID reader 40 that has received this signal demultiplexes the signal and transfers it to an external device. Thus, the RFID tag 1 of the present embodiment is a passive radio wave type wireless tag that does not have a power source (battery) for holding and transmitting identification information. Therefore, compared with an active wireless tag having a battery, it is possible to achieve miniaturization and cost reduction because it does not have a battery.

[0028] The loop-shaped conductor 22 is disposed, for example, at a substantially central portion of the inlay 2 as shown in FIG. 2. The IC chip 21 is disposed so as to overlap above the loop-shaped conductor 22 and is electrically connected to the loop-shaped conductor 22. In the first embodiment, a connection position with the IC chip 21 is provided at a substantially central position in the X direction of one long side portion 222A of the loop-shaped conductor 22. Thereby, when the IC chip 21 is connected to the loop-shaped conductor 22, the IC chip 21 is disposed at the center in the longitudinal direction of the RFID tag 1 and is displaced from the center in the short side direction of the RFID tag 1 to one side (the Y positive direction side in the example of FIG. 2).

[0029] A pair of rectangular conductors 23A and 23B extend from a pair of short side portions 221A and 221B of the loop-shaped conductor 22 to both sides in the longitudinal direction (X direction) of the tag and are formed in a rectangular shape. Note that the “rectangular shape” used in the present embodiment includes a substantially rectangular shape, and includes cases where the lengths of adjacent two sides are slightly different, or cases where adjacent corners are not exactly right angles.

[0030] In addition, in each of the pair of rectangular conductors 23A and 23B, a pair of protruding portions 231 that protrude outward in the short side direction from the loop-shaped conductors 22 at both ends in the short side direction (Y direction) of the tag are provided. One of the rectangular conductors 23A has a pair of protruding portions 231A and 231B, one of the protruding portions 231A protruding toward the positive Y direction side and the other protruding portion 231B protruding toward the negative Y direction side. The other rectangular conductor 23B has a pair of protruding portions 231C and 231D, one of the protruding portions 231C protruding toward the positive Y direction side and the other protruding portion 231D protruding toward the negative Y direction side. In the following description, in each of the pair of rectangular conductors 23A and 23B, the protruding portions 231A and 231C that protrude outward in the short side direction from the loop-shaped conductor 22 from one side in the short side direction of the rectangular shape of the RFID tag 1 (the positive Y direction side in the example of FIG. 2) are also referred to as "a pair of first protruding portions 231A and 231C". Similarly, in each of the pair of rectangular conductors 23A and 23B, the protruding portions 231B and 231D that protrude outward in the short side direction from the loop-shaped conductor 22 from the other side in the short side direction of the rectangular shape of the RFID tag 1 (the negative Y direction side in the example of FIG. 2) are also referred to as "a pair of second protruding portions 231B and 231D".

[0031] In the example of FIG. 2, the outer edge ends in the X direction of each protruding portion 231 are arranged to be at the same position as the outer edge ends in the X direction of the rectangular conductor 23. In FIG. 2, for convenience of explanation, the boundary line on the Y direction center side (the second virtual line VS side) of the portion of the pair of protruding portions 231A and 231B of one of the rectangular conductors 23A and the boundary line on the Y direction center side of the portion of the pair of protruding portions 231C and 231D of the other rectangular conductor 23B are illustrated by dotted lines, but actually, each of the protruding portions 231A to 231D is integrally formed with the rectangular conductors 23A and 23B.

[0032] Furthermore, a pair of rectangular conductors 23A and 23B are provided so as to protrude along the longitudinal direction from the protruding portions 231 toward the central side in the longitudinal direction (X direction) of the tag, and include strip portions 232 formed in strip shape. In one rectangular conductor 23A, strip portions 232A and 232B are respectively formed so as to protrude along the X direction from the pair of protruding portions 231A and 231B toward the positive X direction side. In the other rectangular conductor 23B, strip portions 232C and 232D are respectively formed so as to protrude along the X direction from the pair of protruding portions 231C and 231D toward the negative X direction side. In the example of FIG. 2, the outer edge ends in the Y direction of each strip portion 232 are arranged to be at the same position as the outer edge ends in the Y direction of the protruding portions 231. In the following description, the strip portions 232A and 232C respectively provided so as to protrude along the longitudinal direction from the pair of first protruding portions 231A and 231C toward the central side in the longitudinal direction (X direction in the example of FIG. 2) of the rectangular shape of the RFID tag 1 are also referred to as "a pair of first strip portions 232A and 232C". Similarly, the strip portions 232B and 232D respectively provided so as to protrude along the longitudinal direction from the pair of second protruding portions 231B and 231D toward the central side in the longitudinal direction of the rectangular shape of the RFID tag 1 are also referred to as "a pair of second strip portions 232B and 232D".

[0033] Note that in FIG. 2, for convenience of explanation, the boundary lines between the base end portions on the negative X direction side of the portions of the pair of strip portions 232A and 232B of one rectangular conductor 23A and the respective protruding portions 231A and 231B, and the boundary lines between the base end portions on the positive X direction side of the portions of the pair of strip portions 232C and 232D of the other rectangular conductor 23B and the respective protruding portions 231C and 231D are illustrated by dotted lines, but actually, the strip portions 232A to 232D are integrally formed with the rectangular conductors 23A and 23B.

[0034] In other words, the strip portion 232 includes a pair of first strip portions 232A and 232C provided so as to protrude from the protruding portions 231A and 231C of the pair of rectangular conductors 23A and 23B on one long side portion 222A of the pair of long side portions 222A and 222B of the loop-shaped conductor 22. Similarly, on the other long side portion 222B, the strip portion 232 includes a pair of second strip portions 232B and 232D provided so as to protrude from the protruding portions 231B and 231D of the pair of rectangular conductors 23A and 23B.

[0035] As shown in FIG. 2, each strip portion 232 is preferably formed so as not to overlap with the portion where the IC chip 21 of the loop conductor 22 is installed when viewed from the short side direction (Y direction) of the tag. Thereby, since no conductor pattern intervenes outside the IC chip 21 in the Y direction, it is considered that the wireless transmission performance of the IC chip 21, particularly in the Y direction, can be improved, and the influence of moisture contained in the object to be attached and the influence of the proximity of RFID tags attached to each of the plurality of objects to be attached can be further suppressed.

[0036] Also, the width of each strip portion 232 (the dimension in the Y direction, LB in FIG. 3) is formed to be smaller than the amount of protrusion in the Y direction from the rectangular conductor 23 of each protrusion portion 231. Thereby, a gap (LC in FIG. 3) is formed between each strip portion 232 and the rectangular conductor 23 and the loop conductor 22.

[0037] The pair of rectangular conductors 23A and 23B function as a dipole antenna configured to exhibit resonance characteristics with the IC chip 21 with respect to the frequency of the radio wave for wireless communication (for example, the frequency in the UHF band). The rectangular conductors 23A and 23B as a dipole antenna have an electrical length corresponding to around λ / 2 (λ is the communication wavelength) as a whole. The pair of rectangular conductors 23A and 23B have a structure that realizes impedance conjugate matching with the IC chip 21 with respect to radio waves having a frequency in the vicinity of 920 MHz (for example, 860 MHz to 960 MHz, more preferably 915 MHz to 935 MHz).

[0038] The conductive wiring pattern of the inlay 2 including the loop conductor 22 and the rectangular conductor 23 can be formed by existing methods such as press working, etching, plating of copper foil or aluminum foil, silk screen printing of metal paste, and metal wire. Here, it is formed by etching aluminum.

[0039] As shown in FIG. 2, the conductive wiring pattern of the inlay 2 including the loop-shaped conductor 22 and the rectangular conductor 23 is preferably formed symmetrically with respect to a first virtual line VL passing through the substantially center in the longitudinal direction of the RFID tag 1 (the position where the IC chip 21 is disposed in FIG. 2) in a plan view. The first virtual line VL is a line parallel to the XY plane and extending in the Y direction. The first virtual line VL is also a line that substantially bisects the RFID tag 1 into regions in the X direction. In FIG. 2, the first virtual line VL is indicated by a dashed-dotted line extending along the Y direction.

[0040] Similarly, as shown in FIG. 2, the conductive wiring pattern of the inlay 2 including the loop-shaped conductor 22 and the rectangular conductor 23 is preferably formed symmetrically with respect to a second virtual line VS passing through the substantially center in the short-side direction of the RFID tag 1 in a plan view. The second virtual line VS is a line parallel to the XY plane and extending in the X direction. The second virtual line VS is also a line that substantially bisects the RFID tag 1 into regions in the Y direction. In FIG. 2, the second virtual line VS is indicated by a dashed-dotted line extending along the X direction.

[0041] That is, in the present embodiment, the conductive wiring pattern of the inlay 2 including the loop-shaped conductor 22 and the rectangular conductor 23 is formed to be symmetric with respect to both the X direction and the Y direction.

[0042] Also, as shown in FIG. 2, the pair of rectangular conductors 23A and 23B are preferably formed to protrude in the X direction from the entire region extending in the extending direction (Y direction) of the pair of short-side portions 221A and 221B. That is, it is preferable that the left short-side portion 221A and the rectangular conductor 23A in FIG. 2 are integrally formed, and the right short-side portion 221B and the rectangular conductor 23B in FIG. 2 are integrally formed.

[0043] In addition, in FIG. 2, for convenience of explanation, the boundary line between one rectangular conductor 23A and one short side portion 221A, and the boundary line between the other rectangular conductor 23B and the other short side portion 221B are shown by dotted lines. However, actually, the pair of rectangular conductors 23A and 23B are integrally formed with the loop-shaped conductor 22. That is, the boundary lines between the pair of rectangular conductors 23A and 23B and the pair of short side portions 221A and 221B, the boundary lines between the pair of rectangular conductors 23A and 23B and the four protruding portions 231A to 231D, and the boundary lines between the four protruding portions 231A to 231D and the four strip portions 232A to 232D, which are shown by dotted lines in FIG. 2, are not actually formed on the conductor pattern of the inlay 2.

[0044] Further, the pair of rectangular conductors 23A and 23B may be formed to protrude in the X direction from the pair of short side portions 221A and 221B, or may be configured to protrude in the X direction only from a part of the extending direction (Y direction) of the pair of short side portions 221A and 221B.

[0045] FIG. 3 is a diagram showing an example of the dimensions of each part of the conductor pattern of the inlay 2 shown in FIG. 2. In the dimension example shown in FIG. 3, all the conditions regarding the shapes of the above-mentioned loop-shaped conductor 22 and rectangular conductor 23 are satisfied.

[0046] Here, in the RFID tag 1 of the first embodiment, the dimension in the longitudinal direction (X direction) of the inlay 2 is 70 mm, and the dimension in the short-side direction (Y direction) of the inlay 2 is 14 mm.

[0047] Also, in the example of FIG. 3, the dimension LA in the longitudinal direction (X direction) of each strip portion 232A to 232D is, for example, 14.6 mm, and preferably in the range of 4.6 mm to 19.6 mm. The width dimension LB in the Y direction of each strip portion 232A to 232D is, for example, 0.5 mm, and preferably in the range of 0.5 mm to 1.5 mm. The gap dimension LC in the Y direction between each strip portion 232A to 232D and the rectangular conductors 23A and 23B is, for example, 1.0 mm, and preferably in the range of 1.0 mm to 2.0 mm.

[0048] The dimension LD from the X-negative direction end of the rectangular conductor 23A to the roots of the strip portions 232A and 232B, and the dimension from the X-positive direction end of the rectangular conductor 23B to the roots of the strip portions 232C and 232D is, for example, 15.0 mm. The dimension LE from the installation position of the IC chip 21 on the loop-shaped conductor 22 to both ends in the longitudinal direction (X direction) of the pair of rectangular conductors 23A and 23B is, for example, 34.0 mm. In the case of this example, based on the dimensions LD and LE, the dimension LF from the installation position of the IC chip 21 on the loop-shaped conductor 22 to the roots of the first strip portions 232A and 232C is 19.0 mm.

[0049] As described above, the RFID tag 1 according to the first embodiment includes a loop-shaped conductor 22 and a rectangular conductor 23 formed of the conductive pattern shown in FIG. 2, and can suppress a decrease in communication performance due to the influence of moisture contained in the object to be attached or the influence of proximity of RFID tags attached to a plurality of objects to be attached.

[0050] In the first embodiment, for convenience of explanation, the loop-shaped conductor 22 and the rectangular conductor 23 are shown as separate elements and are separated by a dotted line in FIG. 2. However, in the present embodiment, as described above, the loop-shaped conductor 22 and the rectangular conductor 23 are actually integrally formed, and the division position between the loop-shaped conductor 22 and the rectangular conductor 23 shown by the dotted line in FIG. 2 is only an example. That is, in the first embodiment, not only the rectangular conductor 23 but also at least a part of the loop-shaped conductor 22 may function as an antenna portion. Similarly, at least a part of the rectangular conductor 23 may function as a loop-shaped conductor.

[0051] As shown in FIG. 1, in the RFID tag 1 of the first embodiment, a label paper (film-based tack paper) 3 is further disposed above the inlay 2. The label paper 3 can be printed on the surface on the positive Z-axis side. The material of the label paper 3 can be appropriately selected, and a material other than paper, such as a resin material, may be applied as long as it is printable.

[0052] Further, the label paper 3 is formed with a dimension in the X direction larger than that of the inlay 2. The inlay 2 is disposed at the central portion thereof, and surplus portions that do not overlap with the inlay 2 are provided on both sides in the X direction. On the back surface of the surplus portion on the negative Z-axis side, an adhesive portion 4 having adhesiveness is provided on the contact surface with the object to be attached (the lower surface in FIG. 1). In this way, the inlay 2 and the adhesive portion 4 are arranged so as not to overlap in plan view. In the example of FIG. 1, a pair of adhesive portions 4A and 4B are arranged on the positive X-axis side and the negative X-axis side with respect to the inlay 2.

[0053] The adhesive portion 4 comes into contact with the object to be attached and adheres to the object to be attached by its adhesive force, whereby the entire RFID tag 1 is attached to the object to be attached.

[0054] The adhesive portion 4 is preferably formed of, for example, an adhesive type of hot melt. The hot melt is a thermoplastic adhesive that is solid at room temperature but liquefies by heating and melting and is applied to the adherend, and forms a bond by cooling and solidifying. The adhesive type of hot melt has the property of having an adhesive force on the exposed surface even after cooling and solidifying. Further, the adhesive portion 4 is preferably formed using a bio-derived resource (biomass) or a biodegradable material. The biomass content of the adhesive portion 4 is, for example, 25%.

[0055] Also, a joint portion 5 is laminated on the back surface of the label paper 3 on the negative Z-axis side. The joint portion 5 is joined to the upper surface of the inlay 2 and the upper surface of the adhesive portion 4, whereby the inlay 2 and the adhesive portion 4 are covered by the label paper 3. Further, at the time of lamination, the joint portion 5 can enter the gap formed by the inlay 2 and the label paper 3 above it and fill this gap.

[0056] The joint portion 5 is preferably formed of, for example, a non-adhesive type of hot melt. The non-adhesive type of hot melt is a material that does not have an adhesive force on the exposed surface after cooling and solidifying. Similar to the adhesive portion 4, the joint portion 5 is preferably formed using a bio-derived resource (biomass) or a biodegradable material.

[0057] Further, before use, a release paper 6 is disposed below the adhesive portion 4 of the RFID tag 1. The release paper 6 is formed, for example, to have the same or larger size as the label paper 3, and the label paper 3 and the release paper 6 are adhered by the adhesive portion 4. Thereby, it is possible to prevent the pair of adhesive portions 4A and 4B on both sides in the X direction of the label paper 3 from being exposed to the outside before being used for sticking to the object to be stuck, and the adhesive force can be maintained. When the RFID tag 1 is used, the release paper 6 is peeled off from the RFID tag 1, and the RFID tag 1 is stuck to the object to be stuck by the adhesive portions 4A and 4B of the label paper 3 thus exposed.

[0058] Further, the release paper 6 may be formed to be larger than that illustrated in FIG. 1, and a plurality of RFID tags 1 may be arranged on one release paper 6. Thereby, the manufacturing efficiency and the conveyance efficiency can be improved.

[0059] Note that the thickness in the Z direction (excluding the release paper 6) of the RFID tag 1 of the first embodiment is 80 μm to 260 μm, preferably 150 to 230 μm. Also, the thickness in the Z direction of the adhesive portion 4 is preferably about 10 μm to 30 μm.

[0060] In the RFID tag 1 of the first embodiment, as described above, in a plan view, the inlay 2 and the adhesive portion 4 are arranged so as not to overlap. In the examples of FIGS. 1 and 2, a pair of adhesive portions 4A and 4B are arranged on the positive direction side and the negative direction side of the X axis with respect to the inlay 2. With this configuration, the inlay 2 itself is not directly stuck to the object to be stuck, but is indirectly stuck to the object to be stuck via the adhesive portion 4.

[0061] Note that the laminated structure of the RFID tag 1 is not limited to that shown in FIG. 1. For example, the label paper 3 may be formed to have the same size as the inlay 2. In this case, since the outer edge portion of the label paper 3 cannot contact the object to be attached, the adhesive portion 4 is provided on the entire lower surface of the base material 24 of the inlay 2 facing the object to be attached, and the inlay 2 is directly attached to the object to be attached. Further, in the configuration shown in FIG. 1, an adhesive portion may also be continuously provided between the pair of adhesive portions 4A and 4B to form a single adhesive layer. In this case, the inlay 2 is also directly attached to the object to be attached.

[0062] Further, the RFID tag 1 may be configured such that elements such as a magnetic sheet, a spacer layer, and a dielectric layer are further laminated on the object-to-be-attached side (the lower side in FIG. 1) of the inlay 2. The magnetic sheet is a sheet material containing a magnetic material, and it is preferable to use one having excellent magnetic shielding characteristics against radio waves in the frequency band (for example, the UHF band) used for reading the IC chip 21. The spacer layer is an element that disposes the inlay 2 in a state of being separated from the object to be attached by its thickness, and is preferably formed of an insulator such as a woven or non-woven fabric made of fibers such as cardboard or synthetic resin, or a sheet of an inorganic material such as ceramic glass. The dielectric layer is preferably formed of an insulator material having a relative dielectric constant of about 1.2 to 3.0, whereby the communication distance of the RFID tag 1 can be increased.

[0063] <Application Example of RFID Tag 1> FIG. 4 is a diagram showing an example of a configuration in which the RFID tag 1 according to the first embodiment is attached to a book 30 as an object to be attached. As shown in FIG. 4, when the object to be attached is the book 30, the RFID tag 1 can be attached to, for example, the back surface 31A of the back cover 31. Further, when the object to be attached is the book 30, various bibliographic information related to the book 30 to which this tag is attached can be recorded, for example, in the IC chip 21 of the RFID tag 1.

[0064] Also, when the object to be attached is the book 30, the attachment position of the RFID tag 1 is not limited to the example in FIG. 4, and may be other positions such as the front surface 31B of the back cover 31, the back surface 32A or back surface 32B of the front cover 32, the spine 33, the endpaper 34, the cover 35, etc. In order to accurately read the information from the RFID tag 1, the attachment position of the RFID tag 1 is preferably a portion as close as possible to the outer surface of the book 30 so that there are as few obstacles as possible between the RFID tag 1 and a reading device such as the RFID reader 40 (see FIG. 5).

[0065] FIG. 5 is a diagram showing an example of an information reading method from the RFID tags 1-1 to 1-5 attached to a plurality of books 30-1 to 30-5 as objects to be attached. As shown in FIG. 5, consider a case where RFID tags 1-1 to 1-5 are respectively attached to a plurality of books 30-1 to 30-5, and these plurality of books 30-1 to 30-5 are in a stacked state in the vertical direction.

[0066] In this case, the user approaches the stacked books 30-1 to 30-5 and operates the RFID reader 40 using a small, lightweight and portable reading device such as the RFID reader 40 shown in FIG. 5. Thereby, the information IDs 1 to 5 regarding each of the books 30-1 to 30-5 recorded in each of the RFID tags 1-1 to 1-5 can be collectively read from each of the RFID tags 1-1 to 1-5 attached to each of the books 30-1 to 30-5.

[0067] Note that the reading device may be a fixed type, and the stacked books 30-1 to 30-5 may be placed within the readable range of the reading device to read the information IDs 1 to 5 from each of the RFID tags 1-1 to 1-5. Also, when a plurality of books 30-1 to 30-5 are closely arranged on a bookshelf, that is, when a plurality of books are stacked in the horizontal direction, the information IDs 1 to 5 can be collectively read from each of the RFID tags 1-1 to 1-5 in the same manner as the above-described method.

[0068] Note that this book 30 is made by binding a number of sheets of paper. Also, when sold or stored in a bookstore or stored in a library, as shown in FIG. 5, a number of books 30-1 to 30-5 are often stacked flat. Therefore, for example, when an RFID tag 1 is attached to a cover portion such as a front cover 32 or a back cover 31, or a turn-back 34 or a door 35 close to the cover portion, the RFID tags 1-1 to 1-5 of each of the books 30-1 to 30-5 stacked flat may be arranged to be sandwiched between the upper and lower books. For this reason, conventionally, due to the influence of the proximity of the RFID tags attached to each of the books 30-1 to 30-5 and the influence of moisture contained in the number of sheets of paper forming each of the books 30-1 to 30-5, etc., the communication distance of the RFID tag may decrease, and the reading accuracy of the RFID tag may deteriorate. Note that the same problem may occur when a plurality of books 30 are closely arranged on a bookshelf.

[0069] On the other hand, as described above, the RFID tag 1 of the first embodiment is configured to include a loop-shaped conductor 22 and a rectangular conductor 23 formed of the conductive pattern shown in FIG. 2, so as to suppress a decrease in communication performance due to the influence of moisture contained in the object to be attached (for example, the book 30) or the influence of the proximity of the RFID tags 1-1 to 1-5 attached to each of the plurality of objects to be attached (for example, the books 30-1 to 30-5). Therefore, in particular, if the RFID tag 1 of the first embodiment is applied to an object to be attached formed by laminating a number of sheets of paper such as the book 30, the effect of suppressing a decrease in communication performance can be more significantly exhibited. Further, even in a state where a plurality of books 30-1 to 30-5 are laminated, the same effect can be obtained, so that it is possible to accurately read the information IDs 1 to ID5 from each of the tags 1-1 to 1-5.

[0070] <Effect of RFID tag 1> With reference to FIG. 6, the effect of the RFID tag 1 according to the first embodiment will be further described. FIG. 6 is a diagram for explaining the effect according to the first embodiment, and is a diagram schematically showing that the antenna portion of the RFID tag 1 has current paths of a plurality of electrical lengths L1, L2, and L3.

[0071] In addition, in FIG. 6, for the sake of illustration convenience, the illustration of the portion on the positive direction side (right side of the figure) from the center of the RFID tag 1 in the X direction is omitted. As a result, in FIG. 6, only one of the pair of rectangular conductors 23A and 23B on the X negative direction side, i.e., the rectangular conductor 23A, is illustrated. Similarly, only one of the pair of first strip portions 232A and 232C arranged on the X negative direction side, i.e., the first strip portion 232A, is illustrated, and only one of the pair of second strip portions 232B and 232D arranged on the X negative direction side, i.e., the second strip portion 232B, is illustrated. And in the following description, with reference to FIG. 6, the operation and effect of the portion including one rectangular conductor 23A, the first strip portion 232A, and the second strip portion 232B will be described. However, in the portion including the other rectangular conductor 23B, the first strip portion 232C, and the second strip portion 232D on the X positive direction side not illustrated in FIG. 6, the same operation and effect are achieved.

[0072] As described above, in the RFID tag 1 of the first embodiment, the IC chip 21 is arranged at the center in the longitudinal direction of the RFID tag 1 and is displaced from the center in the short side direction of the RFID tag 1 to one side (the Y positive direction side in the example of FIG. 2). That is, the IC chip 21 is arranged closer to the pair of first strip portions 232A and 232C than the pair of second strip portions 232B and 232D. Also, the lengths in the longitudinal direction (X direction) of the pair of first strip portions 232A and 232C and the pair of second strip portions 232B and 232D, that is, the dimensions LA illustrated in FIG. 3, are all the same.

[0073] In the RFID tag 1 of the first embodiment, due to such an arrangement of the IC chip 21 and the setting of the lengths of the respective strip portions 232, as shown in FIG. 6, the first distance L1 from the IC chip 21 to both ends in the longitudinal direction (X direction) of the pair of rectangular conductors 23A and 23B, the second distance L2 from the IC chip 21 to the tips of the pair of first strip portions 232A and 232C, and the third distance L3 from the IC chip 21 to the tips of the pair of second strip portions 232B and 232D are formed with different lengths. In the case of the dimension example illustrated in FIG. 3, the magnitude relationship of the respective distances L1 to L3 shown in FIG. 6 is the first distance L1 < the second distance L2 < the third distance L3.

[0074] And at least one of the first distance L1, the second distance L2, and the third distance L3 is set to be an electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag 1. The remaining ones of the first distance L1, the second distance L2, and the third distance L3 are set to have an electrical length different from the electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag 1.

[0075] Here, the dimension in the longitudinal direction (X direction) of the antenna portion of the inlay 2, that is, the dimension from the end on the negative X side of the rectangular conductor 23A to the end on the positive X side of the rectangular conductor 23B, is formed to be half the length of the wavelength of the highest frequency among the operating frequencies applicable as the carrier wave frequency in the RFID tag 1. Here, if the highest frequency is f1, the relationship with the wavelength λ1 of this frequency f1 is λ1 = c (speed of light) / f1. And the dimension in the longitudinal direction of the inlay 2 is (λ1) / 2.

[0076] As shown by the dashed line in FIG. 6, the current I1 flowing out from the inlay 2 from the connection portion with the IC chip 21 travels along the X direction in a substantially straight line along the shortest distance toward both ends of the rectangular conductors 23A and 23B. As a result, the length of the current path of the current I1 (that is, the first distance L1) is approximately (λ1) / 2. Therefore, the antenna portion of the inlay 2 can resonate with the radio wave of the carrier wave frequency f1 of the wavelength λ1 and can establish communication with a reader / writer at a desired distance.

[0077] Also, as shown by the solid line in FIG. 6, the current I2 flowing out from the connection part with the IC chip 21 into the inlay 2 first travels along the X direction in a substantially straight line following the shortest distance toward both ends of the rectangular conductors 23A and 23B. Next, when reaching the positions of the ends on the center side in the X direction of the protruding parts 231A and 231C, the traveling direction changes to the positive Y direction side along this end and proceeds. Then, when reaching the positions at the bases of the first strip parts 232A and 232C, the traveling direction changes to the center side in the X direction along the first strip parts 232A and 232C and heads toward the tips of the first strip parts 232A and 232C. As a result, the length of the current path of the current I2 (i.e., the second distance L2) becomes longer than the first distance L1 = (λ1) / 2. Therefore, the antenna part of the inlay 2 can resonate with radio waves of the carrier frequency f2 having a wavelength λ2 longer than the wavelength λ1, and communication can be established with a reader / writer at a desired distance.

[0078] Also, as shown by the dotted line in FIG. 6, the current I3 flowing out from the connection part with the IC chip 21 into the inlay 2 first travels along the X direction in a substantially straight line following the shortest distance toward both ends of the rectangular conductors 23A and 23B. Next, after passing through the short side parts 221A and 221B of the loop-shaped conductor 22, the traveling direction changes to the negative Y direction side and heads toward the ends on the negative Y direction side of the rectangular conductors 23A and 23B. Then, when reaching the ends on the negative Y direction side of the rectangular conductors 23A and 23B, the traveling direction changes to the outside in the X direction along this end and proceeds, and when reaching the positions of the ends on the center side in the X direction of the protruding parts 231B and 231D, the traveling direction changes to the negative Y direction side along this end and proceeds. Further, when reaching the positions at the bases of the second strip parts 232B and 232D, the traveling direction changes to the center side in the X direction along the second strip parts 232B and 232D and heads toward the tips of the second strip parts 232B and 232D. As a result, the length of the current path of the current I3 (i.e., the third distance L3) becomes even longer than the second distance L2 = (λ2) / 2. Therefore, the antenna part of the inlay 2 can resonate with radio waves of the carrier frequency f3 having a wavelength λ3 even longer than the wavelength λ2, and communication can be established with a reader / writer at a desired distance.

[0079] That is, due to the diverse existence of current paths as shown by the dashed-dotted line I1, solid line I2, and dotted line I3 in FIG. 6, the RFID tag 1 according to the first embodiment can resonate with radio waves having carrier frequencies of f1 > f2 > f3 (wavelengths of λ1 < λ2 < λ3), and can establish communication with a reader / writer at a desired distance. In other words, the RFID tag 1 can resonate with radio waves in a wide frequency band from the carrier frequency f1 to f3 to establish communication at a desired distance.

[0080] That is, by selecting the operating frequency from among the plurality of frequencies f1, f2, and f3, at least one of the first distance L1 corresponding to the frequency f1, the second distance L2 corresponding to the frequency f2, and the third distance L3 corresponding to the frequency f3 becomes an electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag 1, ensuring communication performance.

[0081] Also, when the dimension in the longitudinal direction (X direction) of the inlay 2 is standardized to 70 mm and the dimension in the short-side direction (Y direction) is standardized to 14 mm, the first distance L1 becomes constant, so the highest frequency f1 among the applicable operating frequencies becomes a fixed value. On the other hand, by changing the lengths in the longitudinal direction (X direction) of the pair of first strip portions 232A and 232C and the pair of second strip portions 232B and 232D, that is, the dimension LA illustrated in FIG. 3, the second distance L2 and the third distance L3 can be adjusted to any length. Therefore, the magnitudes of the operating frequencies f2 and f3 that are smaller than the frequency f1 can be arbitrarily adjusted. Accordingly, even when the tag size is standardized, the range of the operating frequency of the RFID tag 1 can be arbitrarily set, improving versatility.

[0082] As described above, the RFID tag 1 according to the first embodiment can form a plurality of current paths with different lengths L1, L2, and L3 as described with reference to FIG. 6 by including the antenna pattern of the inlay 2 described with reference to FIG. 2. As a result, it is possible to increase the variation in the operating frequency, so that even if the tag size is reduced, a decrease in communication performance can be suppressed and versatility can be improved. Further, since the inlay 2 includes a plurality of current paths with different electrical lengths, the reception intensity of radio waves at the antenna portion can be increased.

[0083] Further, in the RFID tag 1 according to the first embodiment, the IC chip 21 is disposed at the center in the tag longitudinal direction (X direction) and is displaced from the center in the tag lateral direction (Y direction) to one side. In the case of such an arrangement of the IC chip 21, it is preferable that the longitudinal lengths (LA in FIG. 3) of the pair of first strip portions 232A and 232C and the pair of second strip portions 232B and 232D are all the same. With this configuration, in the antenna pattern in which the IC chip 21 is displaced from the center in the tag lateral direction to one side, the second distance L2 and the third distance L3 can be surely made different in length, so that the variation in the operating frequency can be surely increased.

[0084] [Second Embodiment] The second embodiment will be described with reference to FIGS. 7 and 8.

[0085] FIG. 7 is a plan view of an RFID tag 1A according to the second embodiment. FIG. 7 corresponds to FIG. 2 of the first embodiment. As shown in FIG. 7, in the RFID tag 1A of the second embodiment, of the loop-shaped conductor 22, one long side portion 222A is disposed at the center position in the lateral direction (Y direction) of the RFID tag 1, and a connection position with the IC chip 21 is provided at a substantially central position in the X direction of the one long side portion 222A. Thereby, when the IC chip 21 is connected to the loop-shaped conductor 22, the IC chip 21 is disposed at the center positions in the longitudinal direction and the lateral direction of the RFID tag 1.

[0086] In the second embodiment, portions of one of the long sides 222A of the rectangular conductors 23A and 23B that are on the +Y direction side (the upper side in FIG. 7) extend toward the center in the longitudinal direction from the short sides 221A and 221B, respectively, and are formed with a gap therebetween. The width of this gap in the X direction is larger than the width of the IC chip 21 in the X direction when the IC chip 21 is installed on the loop-shaped conductor 22, as shown in FIG. 7, for example.

[0087] In the second embodiment, the IC chip 21 is disposed at the center in the longitudinal and lateral directions of the RFID tag 1, which is the point where the first virtual line VL and the second virtual line VS intersect.

[0088] Also, with the arrangement of the IC chip 21 as described above, the pair of short sides 221A and 221B and the pair of long sides 222A and 222B of the loop-shaped conductor 22 are arranged to be line-symmetric with respect to the first virtual line VL and are disposed on the -Y direction side of the second virtual line VS. That is, the +Y direction ends of the pair of short sides 221A and 221B in the extending direction (Y direction) are formed to be at substantially the same position as the second virtual line VS, and the -Y direction ends are formed to be at the same position as the -Y direction ends of the rectangular conductors 23A and 23B. The -Y direction end positions of the pair of long sides 222B are the same as the -Y direction end positions of the rectangular conductors 23A and 23B. That is, the long side 222B and the rectangular conductors 23A and 23B are formed such that their -Y direction ends are in a straight line along the X direction. Also, the long side 222A is disposed at the center in the lateral direction (Y direction) of the RFID tag 1.

[0089] Particularly in the second embodiment, as the IC chip 21 is disposed at the center in the longitudinal and lateral directions of the RFID tag 1, the pair of first strip portions 232A and 232C and the pair of second strip portions 232B and 232D are formed to have different lengths in the longitudinal direction. In the example of FIG. 7, the pair of first strip portions 232A and 232C are formed shorter than the pair of second strip portions 232B and 232D.

[0090] The RFID tag 1A of the second embodiment includes a loop-shaped conductor 22 and a rectangular conductor 23 formed by the conductive pattern shown in FIG. 7. Similar to the description with reference to FIGS. 4 and 5 in the first embodiment, it can suppress a decrease in communication performance due to the influence of moisture contained in the object to be attached (for example, the book 30 illustrated in FIG. 4) or the influence of proximity of RFID tags attached to a plurality of objects to be attached (for example, the books 30-1 to 30-5 illustrated in FIG. 5). Therefore, if the RFID tag 1A of the second embodiment is applied to an object to be attached such as the book 30 created by laminating a large number of papers, the effect of suppressing a decrease in communication performance can be more significantly exhibited. Further, even in a state where a plurality of books 30-1 to 30-5 are laminated, the same effect can be obtained, so that information can be accurately read from each tag.

[0091] <Effect of RFID tag 1A> With reference to FIG. 8, the effect of the RFID tag 1A according to the second embodiment will be further described. FIG. 8 is a diagram for explaining the effect according to the second embodiment, and is a diagram schematically showing that the antenna portion of the RFID tag 1A has current paths of a plurality of electrical lengths L1, L2, and L3.

[0092] As described above, in the RFID tag 1 of the second embodiment, the IC chip 21 is disposed at the center position in the longitudinal direction and the lateral direction of the RFID tag 1. That is, the IC chip 21 is disposed at an equal distance from the Y-direction positions of the pair of first strip portions 232A and 232C and the Y-direction positions of the pair of second strip portions 232B and 232D. Further, the pair of first strip portions 232A and 232C and the pair of second strip portions 232B and 232D are formed such that their lengths in the longitudinal direction (X direction), that is, the dimensions LA illustrated in FIG. 3, are different. In the examples of FIGS. 7 and 8, the length LA in the longitudinal direction of the pair of first strip portions 232A and 232C is formed shorter than that of the pair of second strip portions 232B and 232D.

[0093] In the RFID tag 1A of the second embodiment, by such an arrangement of the IC chip 21 and setting the lengths of the respective strip portions 232, as shown in FIG. 8, a first distance L1 from the IC chip 21 to both ends in the longitudinal direction (X direction) of the pair of rectangular conductors 23A and 23B, a second distance L2 from the IC chip 21 to the tips of the pair of first strip portions 232A and 232C, and a third distance L3 from the IC chip 21 to the tips of the pair of second strip portions 232B and 232D are formed with different lengths. In the case of the example in FIG. 8, the magnitude relationship of the respective distances is the first distance L1 < the second distance L2 < the third distance L3. Also, the respective distances L1, L2, and L3 are the same as those in the first embodiment.

[0094] And at least one of the first distance L1, the second distance L2, and the third distance L3 is set to an electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag 1A. The remaining ones of the first distance L1, the second distance L2, and the third distance L3 are set to electrical lengths different from the electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag 1A.

[0095] As shown by the dashed-dotted line in FIG. 8, the current I1A flowing out from the inlay 2 from the connection portion with the IC chip 21 follows the shortest distance substantially linearly along the X direction and heads toward both ends of the rectangular conductors 23A and 23B. As a result, the length of the current path of the current I1A (that is, the first distance L1) becomes approximately (λ1) / 2. Therefore, the antenna portion of the inlay 2 can resonate with the radio wave of the carrier frequency f1 of the wavelength λ1, and communication can be established with a reader / writer at a desired distance. This frequency f1 is the highest frequency among the operating frequencies applicable as the carrier frequency in the RFID tag 1A.

[0096] Also, as shown by the solid line in FIG. 8, the current I2A flowing out from the inlay 2 at the connection portion with the IC chip 21 initially travels along the X direction in a substantially straight line along the shortest distance toward both ends of the rectangular conductors 23A and 23B. Next, after passing through the short sides 221A and 221B of the loop-shaped conductor 22, the traveling direction changes to the positive Y direction side and heads toward the ends of the rectangular conductors 23A and 23B on the positive Y direction side. Then, when reaching the ends of the rectangular conductors 23A and 23B on the positive Y direction side, the traveling direction changes to the outside of the X direction along this end and proceeds. When reaching the positions of the ends on the center side in the X direction of the protruding portions 231A and 231C, the traveling direction changes to the positive Y direction side along this end and proceeds. Further, when reaching the positions at the bases of the first strip portions 232A and 232C, the traveling direction changes to the center side in the X direction along the first strip portions 232A and 232C and heads toward the tips of the first strip portions 232A and 232C. As a result, the length of the current path of the current I2A (i.e., the second distance L2) becomes longer than the first distance L1 = (λ1) / 2. Therefore, the antenna portion of the inlay 2 can resonate with a radio wave having a carrier frequency f2 with a wavelength λ2 longer than the wavelength λ1, and communication can be established with a reader / writer at a desired distance.

[0097] Also, as shown by the dotted line in FIG. 6, the current I3A flowing out from the connection part with the IC chip 21 to the inlay 2 first travels along the X direction in a substantially straight line following the shortest distance toward both ends of the rectangular conductors 23A and 23B. Next, when passing through the short side parts 221A and 221B of the loop-shaped conductor 22, the traveling direction changes to the Y negative direction side and heads toward the Y negative direction side ends of the rectangular conductors 23A and 23B. Then, when reaching the Y negative direction side ends of the rectangular conductors 23A and 23B, the traveling direction changes to the outside of the X direction along this end and proceeds. When reaching the position of the X direction center side ends of the protruding parts 231B and 231D, the traveling direction changes to the Y negative direction side along this end and proceeds. Further, when reaching the base positions of the second strip parts 232B and 232D, the traveling direction changes to the center side of the X direction along the second strip parts 232B and 232D and heads toward the tips of the second strip parts 232B and 232D. As a result, the length of the current path of the current I3A (i.e., the third distance L3) becomes even longer than the second distance L2 = (λ2) / 2. Therefore, the antenna part of the inlay 2 can resonate with radio waves of the carrier frequency f3 having a wavelength λ3 that is even longer than the wavelength λ2, and communication can be established with a reader / writer at a desired distance.

[0098] That is, due to the diverse existence of current paths as shown by the dashed-dotted line I1A, solid line I2A, and dotted line I3A in FIG. 8, the RFID tag 1A according to the second embodiment can resonate with radio waves having carrier frequencies of f1 > f2 > f3 (wavelengths of λ1 < λ2 < λ3) respectively, and communication can be established with a reader / writer at a desired distance. In other words, similar to the first embodiment, the RFID tag 1A according to the second embodiment can resonate with radio waves in a wide frequency band from the carrier frequency f1 to f3 and establish communication at a desired distance.

[0099] That is, similar to the first embodiment, the RFID tag 1A according to the second embodiment can ensure communication performance by selecting an operating frequency from among a plurality of frequencies f1, f2, and f3, such that at least one of the first distance L1 corresponding to the frequency f1, the second distance L2 corresponding to the frequency f2, and the third distance L3 corresponding to the frequency f3 is an electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag 1.

[0100] Further, when the dimension in the longitudinal direction (X direction) of the inlay 2 is standardized to 70 mm and the dimension in the short-side direction (Y direction) is standardized to 14 mm, the first distance L1 becomes constant, so the highest frequency f1 among the applicable operating frequencies becomes a fixed value. On the other hand, by changing the lengths in the longitudinal direction (X direction) of the pair of first strip portions 232A and 232C and the pair of second strip portions 232B and 232D, that is, the dimension LA illustrated in FIG. 3, the second distance L2 and the third distance L3 can be adjusted to arbitrary lengths. For this reason, the magnitudes of the operating frequencies f2 and f3 that are smaller than the frequency f1 can be arbitrarily adjusted. Therefore, similar to the first embodiment, the RFID tag 1A according to the second embodiment can arbitrarily set the range of the operating frequency of the RFID tag 1A even when the tag size is standardized, improving versatility.

[0101] As described above, the RFID tag 1A according to the second embodiment includes the antenna pattern of the inlay 2 described with reference to FIG. 7 and the like, and can form a plurality of current paths having different lengths L1, L2, and L3 as described with reference to FIG. 8. Thereby, it becomes possible to increase the variation of the operating frequency, so that even when the tag size is reduced, a decrease in communication performance can be suppressed and versatility can be improved. Further, since the inlay 2 includes a plurality of current paths having different electrical lengths, the reception intensity of radio waves at the antenna portion can be increased.

[0102] Also, in the RFID tag 1A according to the second embodiment, the IC chip 21 is disposed at the center in the tag longitudinal direction (X direction) and the tag lateral direction (Y direction). In the case of such an arrangement of the IC chip 21, it is preferable that the pair of first strip portions 232A and 232C and the pair of second strip portions 232B and 232D are formed so as to have different lengths in the longitudinal direction (LA in FIG. 3). With this configuration, in the antenna pattern in which the IC chip 21 is disposed at the center in the tag longitudinal direction and the tag lateral direction, the second distance L2 and the third distance L3 can be surely made to have different lengths, so that it is surely possible to increase the variation in the operating frequency.

Example

[0103] Next, examples of the present invention will be specifically described.

[0104] <Settings of the First Test> Example 1 and Comparative Example 1 were set as follows, and a first test was conducted to verify the influence on the performance quality of the RFID tag according to the conductor pattern of the inlay 2.

[0105] <Example 1> Two RFID tags 1 shown in FIGS. 1 and 2 were created with the respective part dimensions shown in FIG. 3. In the following description, these two tags will be denoted as RFID tag 1-1 and RFID tag 1-2 for distinction. The created RFID tag 1-1 was attached to a paper of B5 size 110 kg (108.00 mm × 151.00 mm). The attachment position was set to a position where the long side and the short side of the tag 1-1 are each 13.00 mm away from the outer edge of the paper in a plan view when the longitudinal direction of the paper is the vertical direction.

[0106] As the book 30 to be attached, a paperback comic book of B6 size (width 113 × height 176 mm) was selected. The paper with the RFID tag 1-1 attached was inserted between the back cover 31 and the last page of the paperback so that the surface with the tag attached faced the last page side, and was attached to the back surface 31A of the back cover 31 in the same state.

[0107] Using the book 30 with such an RFID tag 1 attached, a test of the reading performance of the RFID tag 1-1 was conducted based on the guidelines (https: / / www.gs1.org / sites / default / files / docs / epc / Tagged_Item_Test_Methodology.pdf) for measuring and evaluating the performance quality of RFID tags called TIPP (Tagged-Item Performance Protocol). These guidelines are standardized by an international organization called GS1.

[0108] FIG. 9 is a schematic diagram of the measurement environment of the first test according to Example 1. As shown in FIG. 9, four RFID antennas, namely a first antenna 51, a second antenna 52, a third antenna 53, and a fourth antenna 54, were installed in the anechoic chamber 50. The measurement environment shown in FIG. 9 conforms to the provisions of the above guidelines. C50 was applied to the anechoic chamber 50. For the measuring instrument including the first to fourth antennas 51 to 54, Tagformance Pro manufactured by Voyantic was used.

[0109] In the following description, an X1 direction, a Y1 direction, and a Z1 direction that are orthogonal to each other are set. The Z1 direction is the vertical direction of the anechoic chamber 50. The X1 direction and the Y1 direction are the horizontal directions of the anechoic chamber 50, and are the 0-degree and 270-degree directions (see FIG. 10) of the mounting table 55, respectively. Also, hereinafter, for convenience of explanation, there may be cases where the positive direction side of the Z1 axis is also expressed as the upper side and the negative direction side of the Z1 axis is also expressed as the lower side.

[0110] As shown in FIG. 9, the first antenna 51, the second antenna 52, the third antenna 53, and the fourth antenna 54 are arranged to face a predetermined point in the anechoic chamber 50. As shown by the dotted lines in FIG. 9, the facing directions to the predetermined point are arranged at positions where the angles are 0 degrees, 30 degrees, 60 degrees, and 90 degrees respectively from the horizontal direction. Also, the first to fourth antennas 51 to 54 are arranged along the same X1Z1 plane.

[0111] One copy of book 30 with RFID tag 1-1 attached was prepared and placed on the upper surface of mounting table 55 in an anechoic chamber 50. Book 30 was placed such that the front cover 32 was on the upper side and the back cover 31 was on the lower side, that is, RFID tag 1-1 was arranged on the lower end side of book 30. Therefore, book 30 was in a flat stacked state with a stacking quantity of one copy, and one copy of the pages of book 30 was stacked above RFID tag 1-1. As shown by the dotted line in Fig. 9, the height of mounting table 55 was adjusted so that RFID tag 1-1 was arranged at a predetermined point where the opposing directions of the above-described first to fourth antennas 51 to 54 intersect. The first to fourth antennas 51 to 54 were installed such that the distance from RFID tag 1-1 at the predetermined point was all 1 m.

[0112] Also, as shown in Fig. 9, above book 30 placed on mounting table 55, that is, on the front cover 32 of book 30, another RFID tag 1-2 was placed as an element for inhibiting the reading of information by each of antennas 51 to 54 from RFID tag 1-1. RFID tag 1-2 was placed at a position overlapping RFID tag 1-1 in the view in the Z1 direction.

[0113] Fig. 10 is a plan view of the measurement environment shown in Fig. 9. In Fig. 10, for the sake of illustration convenience, only the first antenna 51 arranged horizontally among the first to fourth antennas 51 to 54 is shown, but the relationships with the other second, third, and fourth antennas 52, 53, 54 and the orientations of RFID tag 1-1 and book 30 are the same. Also, although not shown in Fig. 10, an object 60 and RFID tag 1-2 are laminated on the positive Z1 direction side of RFID tag 1-1. As shown in Fig. 10, the state where the long side of RFID tag 1-1 and the back cover 33 of book 30 are placed on mounting table 55 in a direction facing the first to fourth antennas 51 to 54 is defined as the 0-degree direction, and with the predetermined point where the above-described RFID tag 1-1 is arranged as the center, the angle increases as the orientations of the long side of RFID tag 1-1 and the back cover 33 of book 30 rotate in the clockwise direction in Fig. 10. Mounting table 55 is rotatable around a rotation axis along the Z1 direction passing through the upper predetermined point, and book 30 placed on mounting table 55 is configured such that the orientation of the back cover 33 can be changed by rotating mounting table 55.

[0114] Under such conditions, when the long side of the RFID tag 1-1 and the direction of the back cover 33 of the book 30 were set to 10 directions of 0°, 30°, 60°, 120°, 150°, 180°, 210°, 240°, 300°, and 330°, the sensitivities (average output for reading information from the RFID tag 1-1) of the first to fourth antennas 51 to 54 were measured. Also, in the case of two directions of 0° and 180°, the backscatter (response wave intensity from the RFID tag 1-1) of the first to fourth antennas 51 to 54 was measured.

[0115] Using each of the above measurement values, it was determined whether the conditions of the grade set in the TIPP were satisfied. The grade is an evaluation criterion regarding the quality of the reading performance of the RFID tag 1, and multiple types are set. For each grade, a reference value is set for each of the above measurement values. The reference values are different for each grade. When all the measurement values exceed the reference value, it can be evaluated that the conditions of the corresponding grade are satisfied. The grade that can satisfy the conditions when stacking one book 30 flat above the RFID tag 1-1 to be inspected as in the first embodiment was investigated.

[0116] <Comparative Example 1> FIG. 11 is a plan view showing the conductor pattern of the RFID tag 101 used in Comparative Example 1. FIG. 13 corresponds to FIG. 2 and is shown by focusing only on the elements related to the inlay of the RFID tag 101, similar to FIG. 2. In Comparative Example 1, measurements were performed under the same conditions as in Example 1, except that the RFID tag 101 having the existing conductor pattern shown in FIG. 13 was used for the two tags attached to and placed on the book 30.

[0117] As shown in FIG. 11, the RFID tag 101 according to Comparative Example 1 has an IC chip 121, a loop conductor 122, and an antenna portion 123 on an inlay. The inlay has a loop conductor 122 and an antenna portion 123 formed by dry laminating an aluminum sheet on a base material such as a synthetic resin film made of polyethylene terephthalate, polypropylene, etc., and the IC chip 121 is mounted at a specified position.

[0118] Since the IC chip 121 is the same as the IC chip 21 of the embodiments shown in FIGS. 1 and 2, the description thereof will be omitted. The shape and function of the loop conductor 122 are also the same as those of the loop conductor 22 of the embodiments, and it has a pair of short side portions 1221A and 1221B extending in the short side direction of the RFID tag 101 and a pair of long side portions 1222A and 1222B extending in the long side direction. The loop conductor 122 is electrically connected to the IC chip 121 and the antenna portion 123.

[0119] The antenna portion 123 has a structure that realizes impedance conjugate matching with the IC chip 121 for radio waves having a frequency in the vicinity of, for example, 920 MHz (for example, 860 MHz to 960 MHz, more preferably 915 MHz to 935 MHz). The antenna portion 123 includes two conductor portions (conductor portion 123A and conductor portion 123B) as a structure that realizes impedance conjugate matching with the IC chip 121. The conductor portion 123A and the conductor portion 123B are connected to the loop conductor 122 and are conductive wiring patterns extending in directions away from each other from the loop conductor 122 (the positive direction side and the negative direction side of the X axis in the example of FIG. 13). The conductive wiring pattern can be formed by methods such as press working, etching, and plating of copper foil or aluminum foil, silk screen printing of metal paste, existing methods such as metal wires, etc., but here it is formed by etching of aluminum.

[0120] The conductor part 123A and the conductor part 123B are formed symmetrically with respect to a virtual line (corresponding to the first virtual line VL in FIG. 2) passing through the approximate center of the IC chip 121. The virtual line is a line parallel to the XY plane and extending in the Y direction. The virtual line is also a line that approximately bisects the RFID tag 101 in the X direction region.

[0121] As shown in FIG. 11, in the RFID tag 101 according to Comparative Example 1, a pair of conductor parts 123A and 123B of the antenna part 123 are both connected to one long side part 1222B on the positive Y direction side of the loop-shaped conductor 122, the shape of the conductor parts 123A and 123B is not a simple rectangular shape like the rectangular conductor 23 of the above-described embodiment, but includes wiring extending in a zigzag shape, etc., which is a more complex shape, and the conductor pattern is not formed symmetrically with respect to a second virtual line VS (see FIG. 2) passing through the approximate center in the short side direction (Y direction) of the RFID tag 101 in a plan view and extending in the long side direction (X direction), which is different from the RFID tag 1 of the above-described embodiment.

[0122] Also, in the RFID tag 101 used in the comparative example, the size of the inlay was made the same as that of the RFID tag 1 of the above-described embodiment. That is, the dimension in the longitudinal direction (X direction) of the inlay shown in FIG. 11 is 70 mm, and the dimension in the short side direction (Y direction) of the inlay 2 is 14 mm.

[0123] Using each measurement value obtained by performing the same measurement as in Example 1, it was determined whether or not the conditions of the grade set in TIPP were satisfied. Since this Comparative Example 1 is a test environment in which one book of the book 30 is stacked flat above the RFID tag 101 to be inspected in the same manner as in Example 1, the grade that can satisfy the conditions when one book of the book 30 is stacked flat in the same manner as in Example 1 was investigated.

[0124] <Results of the First Test> As a result of the above-described first test, in Example 1, it was confirmed that the conditions of grades M25C and M30E set in TIPP were satisfied.

[0125] On the other hand, in Comparative Example 1, the conditions of grades M25C and M30E could not be satisfied.

[0126] As described above, from the results of the first experiment, even when the RFID tag to be inspected is attached to the book 30 and another RFID tag is laminated above the book 30, compared with the existing conductor pattern of the RFID tag 101 of the comparative example shown in FIG. 11, the conductor pattern of the RFID tag 1 of the present embodiment is less affected by the moisture contained in the pages of the book 30, which is the object to be attached, and is also less affected by the communication by these inhibitors even under the condition that other tags that inhibit the reading of information by each of the antennas 51 to 54 are interposed, and it has been shown that the degradation of the communication performance can be suppressed.

[0127] <Settings of the Second Test> As described below, Example 2 and Comparative Example 2 were set, and a second test was conducted to verify the influence on the communication performance of the RFID tag according to the conductor pattern of the inlay 2.

[0128] <Example 2> In the test environment described with reference to FIG. 9, an information reading test was conducted from the RFID tag 1-1 using only the first antenna 51 arranged in the horizontal direction among the four RFID antennas. The direction of the long side of the RFID tag 1-1 placed on the mounting table 55 was set to the above-described 0-degree direction, and the long side of the RFID tag 1-1 was made to face the first antenna 51.

[0129] Under such conditions, the frequency characteristics of the RFID tag 1-1 were measured. The measurement frequency band of the radio wave for wireless communication during the measurement was set to 800 to 1000 MHz, and the EIRP (Equivalent Isotropically Radiated Power) was set to 3.28 W. The frequency measurement was performed in a test environment where only the RFID tag 1-1 to be inspected was placed alone at a predetermined point on the mounting table 55, that is, the book 30 and other RFID tags 1-2 were removed from the state shown in FIG. 9. Also, in Example 2, different from Example 1, the distance of the first antenna 51 from the mounting position of the RFID tag 1-1 on the mounting table 55 was made changeable.

[0130] <Comparative Example 2> In Comparative Example 2, measurements were performed under the same conditions as in Example 2, except that the RFID tag 101 having the existing conductor pattern shown in FIG. 11 was used for the tag to be inspected placed at a predetermined point on the mounting table 55.

[0131] <Results of the Second Test> FIG. 12 is a diagram showing the frequency characteristics of Example 2 and Comparative Example 2 measured in the second test. FIG. 12(A) shows the frequency characteristics of Example 2, and FIG. 12(B) shows the frequency characteristics of Comparative Example 2. The horizontal axis in each of the diagrams (A) and (B) represents the frequency (MHz) of the radio wave for wireless communication, and the vertical axis represents the communication possible distance (m) from each of the RFID tags 1-1, 101 to the first antenna 51. In FIG. 12, the upper and lower limits of the frequency at which the communication possible distance is about 13 m or more in each frequency characteristic are shown by thick dotted lines, and the range of the frequency between these upper and lower limits is shown by thick dotted line arrows A and B. The range of these arrows A and B is defined as the "peak frequency" of each frequency characteristic.

[0132] As shown by arrow B in FIG. 12(B), in Comparative Example 2, due to the miniaturization of the tag size, for example, the area of the gap portion of the loop-shaped conductor 122 being reduced, it was confirmed that the range B of the peak frequency shifted to the lower frequency side. On the other hand, in Example 2, by providing the first strip portions 232A, 232C and the second strip portions 232B, 232B in the antenna portion of the tag, the range of frequencies applicable to the carrier wave can be increased. Therefore, as shown by arrow A in FIG. 12(A), it was confirmed that the range A of the peak frequency can be maintained on the higher frequency side than in Comparative Example 2, and the peak frequency can be maintained in a wider frequency band than in Comparative Example 2.

[0133] <Settings of the Third Test> Examples 3 to 8 and Comparative Example 3 were set as follows, and a third test was conducted to verify the influence on the communication performance of the RFID tag according to the conductor pattern of the inlay 2.

[0134] <Example 3> In a simulation environment, a model of the RFID tag 1 having the conductive pattern of the inlay 2 shown in FIGS. 1 and 2 was created using the respective dimensions shown in FIG. 3. That is, the outer dimensions of the inlay 2 were set to 70×14 mm, and the dimension LA in the tag longitudinal direction (X direction) of the first strip portions 232A and 232C and the second strip portions 232B and 232D was set to 14.6 mm (see FIG. 3). Further, the width dimension LB in the tag transverse direction (Y direction) of each of the strip portions 232A to 232D was set to 0.5 mm, and the gap dimension LC in the tag transverse direction between each of the strip portions 232A to 232D and the rectangular conductors 23A and 23B was set to 1.0 mm.

[0135] Using the created model, a wireless communication operation simulation was performed. The measurement frequency band of the radio wave for wireless communication was set to 800 to 1000 MHz, and the VSWR (Voltage Standing Wave Ratio) characteristics were measured in the simulation environment. Further, the voltage value around the IC chip 21 in the inlay 2 was measured at the use frequency at which the minimum value in the VSMR characteristics, that is, the value in the state where the sensitivity of the RFID tag 1 is the best, was taken.

[0136] <Example 4> In the model of the RFID tag 1, measurements were performed under the same conditions as in Example 3, except that the dimension LA in the tag longitudinal direction of the first strip portions 232A and 232C and the second strip portions 232B and 232D was shortened by 5 mm to 9.6 mm.

[0137] <Example 5> In the model of the RFID tag 1, measurements were performed under the same conditions as in Example 3, except that the dimension LA in the tag longitudinal direction of the first strip portions 232A and 232C and the second strip portions 232B and 232D was shortened by 10 mm to 4.6 mm.

[0138] <Example 6> In the model of the RFID tag 1, measurements were performed under the same conditions as in Example 3, except that the dimension LA in the tag longitudinal direction of the first strip portions 232A and 232C and the second strip portions 232B and 232D was lengthened by 5 mm to 19.6 mm.

[0139] <Example 7> In the model of the RFID tag 1, measurements were carried out under the same conditions as in Example 3, except that the width dimension LB in the tag short-side direction of each strip portion 232A to 232D was increased by 1 mm to 1.5 mm.

[0140] <Example 8> In the model of the RFID tag 1, measurements were carried out under the same conditions as in Example 3, except that the gap dimension LC in the tag short-side direction between each strip portion 232A to 232D and the rectangular conductors 23A, 23B was increased by 1 mm to 2.0 mm.

[0141] <Comparative Example 3> In the model of the RFID tag 1, measurements were carried out under the same conditions as in Example 3, except that all of the first strip portions 232A, 232C and the second strip portions 232B, 232D were deleted.

[0142] <Results of the Third Test> The results of the third test are shown in Table 1 below. The VSMR numerical values shown in Table 1 indicate the minimum values in the VSMR characteristics, that is, the values in the state where the sensitivity of the RFID tag is the best. The frequency at which the minimum value was taken was within the range of 923 to 925 (MHz) in all of Examples 3 to 8 and Comparative Example 3.

[0143]

Table 1

[0144] As shown in Examples 3 to 6 of Table 1, it was shown that as the dimension LA of the strip portions 232A to 232D was increased from 4.6 mm to 14.6 mm, the VSWR decreased and the sensitivity of the RFID tag 1 improved. On the other hand, when the dimension LA was further extended to 19.6 mm, it was shown that the VSMR slightly increased and the sensitivity slightly decreased compared to the case of 14.6 m. Similarly, as shown in Examples 3 to 6, as the dimension LA of the strip portions 232A to 232D was increased from 4.6 mm to 14.6 mm, the voltage value of the inlay 2 around the IC chip 21 increased and the sensitivity of the RFID tag 1 improved. On the other hand, when the dimension LA was further extended to 19.6 mm, it was shown that the voltage value slightly decreased and the sensitivity slightly decreased compared to the case of 14.6 m.

[0145] On the other hand, as shown in Comparative Example 3 of Table 1, when the strip portions 232A to 232D were not present, the VSMR increased significantly compared to the examples, and the voltage value of the inlay 2 around the IC chip 21 decreased at each stage, indicating that the sensitivity of the RFID tag deteriorated.

[0146] From the above, in the RFID tag 1, when the outer dimensions of the inlay 2 are 70×14 mm, it is preferable that the dimension LA of each of the strip portions 232A to 232D is in the range of 4.6 mm to 19.6 mm, more preferably 9.4 mm to 19.6 mm, still more preferably 14.6 mm to 19.6 mm, and most preferably 14.6 mm.

[0147] Also, as shown in Example 7 of Table 1, when the width dimension LB in the tag short-side direction of each strip portion 232A to 232D was increased by 1 mm with respect to Example 3 to 1.5 mm, the VSMR increased. That is, it was shown that the VSMR increased as the width dimension LB of the strip portions 232A to 232D was made thicker. However, when the width dimension LB was 1.5 mm, the VSMR was about the same as in Example 5, and the VSMR was significantly lower than in Comparative Example 3, and the voltage value around the IC chip 21 was also significantly larger. Therefore, it can be said that the sensitivity of the RFID tag 1 is within an acceptable range. Thereby, in the RFID tag 1, when the outer dimensions of the inlay 2 are 70 × 14 mm, it is shown that the width dimension LB in the tag short-side direction of each strip portion 232A to 232D is preferably 0.5 mm to 1.5 mm, and more preferably 0.5 mm.

[0148] Also, as shown in Example 8 of Table 1, when the gap dimension LC in the tag short-side direction between each strip portion 232A to 232D and the rectangular conductors 23A and 23B was increased by 1 mm with respect to Example 3 to 2.0 mm, the VSMR increased. That is, it was shown that the VSMR increased as the strip portions 232A to 232D were separated from the rectangular conductors 23A and 23B. However, even when the gap dimension LC was 2.0 mm, the VSMR was about the same as in Example 5, and the VSMR was significantly lower than in Comparative Example 3, and the voltage value around the IC chip 21 was also significantly larger. Therefore, it can be said that the sensitivity of the RFID tag 1 is within an acceptable range. Thereby, in the RFID tag 1, when the outer dimensions of the inlay 2 are 70 × 14 mm, it is shown that the gap dimension LC in the tag short-side direction between each strip portion 232A to 232D and the rectangular conductors 23A and 23B is preferably 1.0 mm to 2.0 mm, and more preferably 1.0 mm.

[0149] The above-described embodiments have been explained with reference to specific examples. However, the present disclosure is not limited to these specific examples. As long as those skilled in the art appropriately make design changes to these specific examples and they have the features of the present disclosure, they are included in the scope of the present disclosure. Each element, its arrangement, conditions, shape, etc. included in each of the above-described specific examples are not limited to those illustrated and can be appropriately changed. Each element included in each of the above-described specific examples can be appropriately combined as long as no technical contradiction occurs.

[0150] In the above embodiment, the shape of the inlay 2 of the RFID tags 1 and 1A, particularly the shape of the antenna pattern including the loop-shaped conductor 22 and the pair of rectangular conductors 23A and 23B, is illustrated as being formed in a horizontally long rectangular shape in a plan view seen from the Z direction, with the X direction being the longitudinal direction (the first direction) and the Y direction being the short-side direction (the second direction) as shown in FIGS. 2 and 7. However, the shape of the inlay 2 may be other than rectangular. For example, it may be formed in a substantially square shape where the dimension in the first direction is equal to the dimension in the second direction, or a vertically long rectangular shape in the figure where the dimension in the first direction is shorter than the dimension in the second direction, that is, the longitudinal and short-side directions are interchanged compared to the examples in FIGS. 2 and 7, or any rectangular shape.

[0151] Also, in the above embodiment, the shape of the RFID tags 1 and 1A is illustrated as being formed in a rectangular shape in a plan view seen from the Z direction, with the X direction being the longitudinal direction (the first direction) and the Y direction being the short-side direction (the second direction) as shown in FIGS. 2 and 7. However, the tag shape may be other than rectangular. For example, the shape of the RFID tag may be an elliptical shape, a trapezoidal shape, a rhombus shape, a circular shape, a square shape, etc. Note that even when the shape of the RFID tag is a shape other than rectangular, the shape of the inlay 2 does not necessarily have to be the same as the tag shape and may be the above-described rectangular shape.

Explanation of Reference Numerals

[0152] 1, 1A RFID tags 21 IC chip 22 Loop-shaped conductor 23A, 23B Pair of rectangular conductors The first protrusion of 231A and 231C The second protrusion of 231B and 231D The first strip portion of 232A and 232C The second strip portion of 232B and 232D L1 The first distance L2 The second distance L3 The third distance X Longitudinal direction (first direction) Y Lateral direction (second direction)

Claims

1. An RFID tag, comprising: an IC chip on which identification information is recorded; a loop conductor formed in a ring shape and connected to the IC chip; a pair of rectangular conductors extending from both sides of the loop conductor in a first direction and formed in a rectangular shape; in each of the pair of rectangular conductors, a pair of first protrusions protruding outward from the rectangular conductor in a second direction orthogonal to the first direction; in each of the pair of rectangular conductors, a pair of second protrusions protruding outward from the rectangular conductor in the second direction from the other side of the second direction; a pair of first strip portions respectively protruding along the first direction from the pair of first protrusions toward the center side in the first direction and formed in a strip shape; a pair of second strip portions respectively protruding along the first direction from the pair of second protrusions toward the center side in the first direction and formed in a strip shape; wherein a first distance from the IC chip to both end portions of the pair of rectangular conductors in the first direction, a second distance from the IC chip to the tips of the pair of first strip portions, and a third distance from the IC chip to the tips of the pair of second strip portions are formed with different lengths, at least one of the first distance, the second distance, and the third distance is set to be an electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag, and the remaining ones of the first distance, the second distance, and the third distance are set to have electrical lengths different from the electrical length that is a multiple of 1 / 4 of the wavelength of the operating frequency of the RFID tag. An RFID tag.

2. The IC chip is disposed at the center in the first direction and is displaced by a certain amount from the center in the second direction to one side, and the lengths of the pair of first strip portions and the pair of second strip portions in the first direction are the same. The RFID tag according to Claim 1.

3. The IC chip is disposed at the center in the first direction and at the center in the second direction, and the pair of first strip portions and the pair of second strip portions are formed such that their lengths in the first direction are different. The RFID tag according to Claim 1. ​

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