RFID tag and hanging tag

Abstract

An RFID tag according to the present invention comprises: an antenna part extending from a loop-shaped conductor to one side of the tag in the longitudinal direction; and an antenna part extending to the other side. The loop-shaped conductor is disposed closer to the antenna part side than a central part in the longitudinal direction. The antenna part has a connection part connected to the loop-shaped conductor, a widened part connected to the connection part and formed such that the dimension of the tag in the transverse direction increases as the distance from the connection part increases in the longitudinal direction; and a rectangular part connected to the widened part and formed in a rectangular shape. The widened part is provided with an opening formed by hollowing out the central portion. The antenna part is formed such that the maximum length of a current path is equal to the length of a current path of the antenna part in the longitudinal direction.

Description

RFID tags and hang tags

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to RFID tags and hang tags.

[0002] 2. Description of the Related Art A method is known for managing items with high accuracy and ease by attaching an RFID (Radio Frequency Identification) tag to the item to be managed and reading and writing information about the item to and from the tag.

[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.

[0004] JP 2002-326474

[0005] Generally, books are made by binding together many sheets of paper. Furthermore, many books are often stacked flat when sold or stored in bookstores or libraries. For this reason, when RFID tags are attached to cover parts such as the front and back covers, or to endpapers or pages close to the cover parts, the RFID tags of each book stacked flat may be sandwiched between the books above and below it. In such an arrangement, the RFID tags attached to each book may be affected by the proximity of each other and the moisture contained in the many sheets of paper that make up the book, which may reduce the communication distance of the RFID tags and degrade the RFID tag reading accuracy. A similar problem may occur when multiple books are closely stacked on a bookshelf. Hereinafter, this problem will be referred to as "deterioration of stackability."

[0006] Such a decrease in stackability can occur in stackable articles other than books as well.

[0007] An object of the present invention is to provide an RFID tag and a tag that can suppress a decrease in communication performance and also a decrease in stackability.

[0008] An RFID tag according to an aspect of an embodiment of the present invention comprises an IC chip on which identification information is recorded, a loop-shaped conductor extending in a short direction of the RFID tag and formed in an annular shape having a pair of opposite side portions arranged opposite to each other at both ends in a longitudinal direction, and connected to the IC chip, a first antenna portion extending from one of the pair of opposite side portions to one side in the longitudinal direction, and a second antenna portion extending from the other of the pair of opposite side portions to the other side in the longitudinal direction, the loop-shaped conductor being positioned offset toward the first antenna portion from a center portion in the longitudinal direction, The portion has a connection portion that connects to the loop-shaped conductor, a widening portion that is connected to the connection portion on the opposite side of the loop-shaped conductor in the longitudinal direction and is formed so that the dimension in the short direction increases the further away from the connection portion along the longitudinal direction, and a rectangular portion that is connected to the widening portion on the opposite side of the connection portion in the longitudinal direction and is formed in a rectangular shape, and the widening portion has an opening that is formed by hollowing out a central portion, and the first antenna portion is formed so that the maximum length of the current path is equal to the longitudinal length of the current path of the second antenna portion.

[0009] According to this aspect, even in an antenna pattern in which the loop conductor is biased toward the first antenna unit from the center of the tag's longitudinal direction, the lengths of the current paths of the current flowing from the IC chip to the inlay can be adjusted to be equal in the first and second antenna units connected to the loop conductor, thereby suppressing degradation of communication performance. Furthermore, even when multiple RFID tags are stacked and placed in close proximity, when the second antenna unit of any tag communicates with an external communication device, communication can be performed through the opening of the second antenna unit of another tag located between them. This effectively suppresses interference and communication disruption caused by the second antenna units of other tags, thereby suppressing degradation of stackability of RFID tags.

[0010] In an RFID tag according to another aspect of the embodiment of the present invention, the first antenna portion may be configured to have a first wire portion connected to the loop-shaped conductor and extending along the longitudinal direction to near one end of the RFID tag in the longitudinal direction, and a second wire portion extending from the end of the first wire portion along the lateral direction to near the end of the RFID tag in the lateral direction.

[0011] According to this aspect, even when the space on the tag for the first antenna unit is small compared to the second antenna unit, the length of the current path of the first antenna unit can be increased and easily adjusted to be equal to the length of the current path of the second antenna unit.

[0012] In an RFID tag according to another aspect of the embodiment of the present invention, the connection portion may be configured to have, in at least a portion of the longitudinal direction, a constant width portion that has a predetermined width in the longitudinal direction and extends in the lateral direction.

[0013] According to this aspect, disconnection of the connection portion can be prevented, and the second antenna portion can be more reliably connected to the loop-shaped conductor.

[0014] A tag according to another aspect of the present invention is a tag to which the above-described RFID tag is attached, and includes a perforation provided at a position that intersects with the equal-width portion of the RFID tag.

[0015] According to this aspect, the second antenna portion can be prevented from being completely severed when the perforation is formed. Also, since the relative positional relationship between the perforation and the RFID tag can be tolerated within the range of the width dimension of the equal-width portion, the manufacturing precision of the tag incorporating the RFID tag can be relaxed.

[0016] According to the present disclosure, it is possible to provide an RFID tag and a tag that can suppress a decrease in communication performance and also a decrease in stackability.

[0017] 1 is a plan view of the RFID tag shown in FIG. 1 as viewed from above; FIG. 2 is a diagram showing an example of dimensions of each part of the conductor pattern of the inlay shown in FIG. 2;

[0018] Hereinafter, embodiments will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0019] First Embodiment A first embodiment will be described with reference to FIGS.

[0020] In the following description, the X, Y, and Z directions are perpendicular to one another. 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 lateral direction of each component 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. For ease of explanation, the positive side of the Z axis may be referred to as the front side or upper side, and the negative side of the Z axis may be referred to as the back side or lower side.

[0021] <Structure of RFID tag 1> Fig. 1 is a cross-sectional view of a laminated structure of an RFID tag 1 according to an embodiment. Fig. 2 is a plan view of the RFID tag 1 shown in Fig. 1 as viewed from above. Fig. 2 focuses on the elements related to the inlay 2 in Fig. 1 . The RFID tag 1 is a substantially planar device that is attached to an object to which it is attached. As shown in Figs. 1 and 2, the RFID tag 1 has an inlay 2 built in.

[0022] Examples of objects to be affixed include items such as books and magazines that are typically stacked vertically or horizontally during storage, items formed by stacking large amounts of paper like books and magazines, and items formed from moisture-retaining materials like paper like books and magazines. Examples of such items include cards such as trading cards, stationery such as clear files and notebooks, food items such as sweets, newspapers, tickets, and stamps. Furthermore, examples of objects to be affixed include tags 10 that are attached to products in stores, as will be described later with reference to FIG. 8 . Tags 10, also known as price tags or product tags, are pieces of paper that display information about the product, such as the product name and price, related to the product to which they are attached.

[0023] The RFID tag 1 of this embodiment is preferably flexible and can be attached to an adherend even if the surface of the adherend is curved. Even when bent, the RFID tag 1 of this embodiment can exhibit good communication performance and can be used to identify objects with curved surfaces, thereby diversifying its applications.

[0024] 2, the inlay 2 includes an IC chip 21 in which identification information is recorded, a loop conductor 22 connected to the IC chip 21, and a pair of antenna units 23A and 23B. In the following description, the pair of antenna units 23A and 23B may be collectively referred to as the "antenna unit 23."

[0025] The inlay 2 has a loop-shaped conductor 22 and an antenna part 23 formed by dry laminating an aluminum sheet on a base material 24 such as a synthetic resin film such as polyethylene terephthalate or polypropylene, and an IC chip 21 mounted at a specified position.

[0026] As shown in FIG. 2 , the inlay 2 is formed in a generally rectangular shape with the X direction as the longitudinal direction and the Y direction as the transverse direction in a plan view. For convenience of the following explanation, a first imaginary line VL and a second imaginary line VS are illustrated in FIG. 2 , but these imaginary lines VL and VS are not actually printed on the RFID tag 1. The first imaginary line VL passes through approximately the longitudinal center of the inlay 2 of the RFID tag 1 in a plan view. The first imaginary line VL is a line parallel to the XY plane and extending in the Y direction. The first imaginary line VL also divides the RFID tag 1 into approximately two equal regions in the X direction. In FIG. 2 , the first imaginary line VL is indicated by a dashed line extending along the Y direction. The second imaginary line VS passes through approximately the transverse center of the inlay 2 of the RFID tag 1 in a plan view. The second imaginary line VS is a line parallel to the XY plane and extending in the X direction. The second imaginary line VS also divides the RFID tag 1 into approximately two equal regions in the Y direction. In Fig. 2, the second imaginary line VS is indicated by a dashed line extending along the X direction.

[0027] The IC chip 21 has an internal capacitance, and the inductance of the antenna section 23 and the internal capacitance of the IC chip 21 form a matching circuit.

[0028] The loop-shaped conductor 22 is a conductive wiring pattern having a loop shape (annular) of one turn or less when viewed from the Z direction. The loop-shaped conductor 22 may be configured to extend at least in the short-side direction (Y direction) of the RFID tag 1 and have a pair of opposite side portions 221A, 221B arranged opposite both ends in the longitudinal direction (X direction). In this embodiment, as shown in FIG. 2 , the loop-shaped conductor 22 is formed in a rectangular annular shape consisting of a first pair of opposite sides extending in the Y direction and a second pair of opposite sides extending in the X direction. The pair of opposite side portions 221A, 221B corresponds to the first pair of opposite sides described above. One opposite side portion 221A of the pair of opposite side portions 221A, 221B is arranged on the positive X direction side of the loop-shaped conductor 22, and the other opposite side portion 221B is arranged on the negative X direction side of the loop-shaped conductor 22. The term "rectangular" used in this embodiment includes a substantially rectangular shape, and also includes cases where the lengths of two adjacent sides are slightly different, or where adjacent corners are not exact right angles.

[0029] The loop conductor 22 is electrically connected to the IC chip 21 and the antenna portion 23. When the identification information recorded on the IC chip 21 is read using a communication device such as an RFID reader, when the antenna portion 23 of the inlay 2 receives UHF radio waves, for example, radio waves around 920 MHz, a current flows through the loop conductor 22 due to resonance. This generates an electromotive force that operates the IC chip 21. 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 an RFID reader using radio waves around 920 MHz as a carrier wave. The communication device that receives this signal decodes the signal and transfers it to an external device. As such, the RFID tag 1 of this embodiment is a passive radio wave-based wireless tag that does not have a power source (battery) for storing and transmitting identification information. Therefore, compared to active wireless tags that require a battery, the lack of a battery allows for smaller size and lower cost.

[0030] In the RFID tag 1 of the first embodiment, the loop conductor 22 is positioned offset to one side from the longitudinal center of the inlay 2. In the example of Fig. 2 , the loop conductor 22 is positioned offset to the X-positive side (the right side in Fig. 2 ) from a first imaginary line VL shown in the longitudinal center of the inlay 2, i.e., toward one antenna unit 23A (first antenna unit) of the pair of antenna units 23. The IC chip 21 is positioned above and superimposed on the loop conductor 22 and electrically connected to the loop conductor 22. In the first embodiment, a connection position with the IC chip 21 is provided in a portion of the rectangular loop conductor 22 that corresponds to one side of a second pair of opposite sides extending in the X direction that is positioned on the Y-positive side.

[0031] The pair of antenna portions 23A, 23B are formed extending from a pair of opposite side portions 221A, 221B of the loop-shaped conductor 22 to both sides in the longitudinal direction (X direction) of the tag. One antenna portion 23A (first antenna portion) extends from one opposite side portion 221A to one side in the longitudinal direction of the tag (X positive direction side). The other antenna portion 23B (second antenna portion) extends from the other opposite side portion 221B to the other side in the longitudinal direction of the tag (X negative direction side). In the first embodiment, as described above, the loop-shaped conductor 22 is positioned offset toward one antenna portion 23A from the center portion in the longitudinal direction of the inlay 2, so that the longitudinal dimension (X direction) of one antenna portion 23A on the side to which the loop-shaped conductor 22 is offset is shorter than the other antenna portion 23B.

[0032] In the example of FIG. 2 , one antenna section 23A has a first wire section 231 , a second wire section 232 , and a rectangular section 233 .

[0033] The first line portion 231 is a portion that connects to one opposite side portion 221A of the loop-shaped conductor 22. The first line portion 231 is formed to have approximately the same width as the one opposite side portion 221A, extends from the end of the one opposite side portion 221A on the Y-positive side toward the Y-positive side, then bends at approximately a right angle toward the X-positive side, extends in the X-positive direction, and reaches the vicinity of the end of the RFID tag 1 on the X-positive side.

[0034] The second line portion 232 is connected to the end of the first line portion 231 on the X-positive side, and is formed to extend in the Y-negative direction with approximately the same width and reach near the end of the RFID tag 1 on the Y-negative side.

[0035] The rectangular portion 233 is a rectangular portion connected to the end of the second line portion 232 on the negative Y direction side. The rectangular portion 233 is formed, for example, so that the length of each side is greater than the width of the first line portion 231 and the second line portion 232.

[0036] The other antenna portion 23B has a connecting portion 234, a widened portion 235, and a rectangular portion 236. The connecting portion 234 is a portion that connects to the other opposite side portion 221B of the loop conductor 22.

[0037] The widening portion 235 is connected to the connection portion 234 on the opposite side of the loop-shaped conductor 22 in the longitudinal direction (X direction), and is formed so that the dimension in the short direction (Y direction) increases as it moves away from the connection portion 234 along the longitudinal direction.

[0038] The rectangular portion 236 is connected to the widened portion 235 on the side opposite the longitudinal connecting portion 234 and is formed in a rectangular shape. In the example of Fig. 2, the rectangular portion 236 is formed in a rectangular shape consisting of a first pair of opposite sides extending in the Y direction and a second pair of opposite sides extending in the X direction. The dimension of the rectangular portion 236 in the Y direction is larger than the dimension of the widened portion 235 at the end on the negative X direction side.

[0039] An opening 237 is provided in the center of the widened portion 235. The opening 237 is formed by hollowing out the center of the widened portion 235. In the example of FIG. 1 , the widened portion 235 and the opening 237 are both formed in a trapezoidal shape with their upper and lower sides facing each other in the X direction, and their central axes in the Y direction overlap with the second imaginary line VS. The widened portion 235 and the opening 237 are both formed in a shape that is line-symmetrical with respect to the second imaginary line VS. As a result, the widened portion 235 is formed so that portions corresponding to a pair of oblique sides of the trapezoid extend with equal widths in the X direction, and the portion corresponding to one oblique side is positioned on the positive Y side of the second imaginary line VS, and the portion corresponding to the other oblique side is positioned on the negative Y side of the second imaginary line VS.

[0040] The widened portion 235 and the opening 237 may have a shape other than a trapezoidal shape.

[0041] Furthermore, it is preferable that the connecting portion 234 has, at least in a portion of its longitudinal direction, a constant-width portion 238 that has a predetermined width in the tag longitudinal direction (X direction) and extends in the tag lateral direction (Y direction). In the example of Fig. 2, the constant-width portion 238 is located at the end of the connecting portion 234 on the negative X side. As a result, the end of the widened portion 235 on the positive X side is connected to the constant-width portion 238 of the connecting portion 234.

[0042] In the first embodiment, as described above, the loop conductor 22 is positioned offset toward the positive X-direction with respect to the center of the inlay 2 in the X-direction. Therefore, when only the X-direction dimensions of the pair of antenna units 23A and 23B are considered, the antenna unit 23A on the side where the loop conductor 22 is offset is shorter than the other antenna unit 23B. In this case, if each antenna unit were simply rectangular, the length of the current path from the IC chip 21 to the inlay 2, which travels the shortest distance in a substantially straight line along the X-direction to reach the edge of the X-direction, would be different on both sides of the loop conductor 22 in the X-direction. The current path of one antenna unit 23A is shorter than the current path of the other antenna unit 23B. Such different current path lengths may affect the communication performance of the RFID tag 1.

[0043] Therefore, in this embodiment, one antenna unit 23A has a first wire unit 231 that extends mainly along the X-positive direction to near the end of the RFID tag 1 on the X-positive side, and a second wire unit 232 that extends from the end of the first wire unit 231 along the Y-negative direction to near the end of the RFID tag 1 on the Y-negative side. This configuration allows the length of the current path of one antenna unit 23A to be increased and easily adjusted to be equal to the length of the current path of the other antenna unit 23B, even when the space on the tag for one antenna unit 23A is small relative to the other antenna unit 23B. As a result, even in an antenna pattern in which the loop conductor 22 is biased toward one antenna unit 23A from the center of the tag longitudinal direction, the maximum lengths of the current paths of the current flowing from the IC chip 21 to the inlay 2 can be adjusted to be more equal in the antenna units 23A and 23B connected to both ends of the loop conductor 22 in the X-direction, thereby suppressing degradation of communication performance.

[0044] In this embodiment, by configuring the antenna unit 23A as described above, the pair of antenna units 23A, 23B function as dipole antennas configured to exhibit resonance characteristics with the IC chip 21 for radio wave frequencies for wireless communication (e.g., UHF band frequencies). The pair of antenna units 23A, 23B as dipole antennas have an overall electrical length equivalent to approximately λ / 2 (λ is the communication wavelength). The pair of antenna units 23A, 23B have a structure that achieves impedance conjugate matching with the IC chip 21 for radio waves with frequencies, for example, around 920 MHz (e.g., 860 MHz to 960 MHz, more preferably 915 MHz to 935 MHz).

[0045] The conductive wiring pattern of the inlay 2, including the loop-shaped conductor 22 and the antenna portions 23A and 23B, can be formed by existing methods such as pressing or etching copper foil or aluminum foil, plating, silkscreen printing of metal paste, or metal wire, but here it was formed by etching aluminum.

[0046] In this embodiment, the antenna portion 23A, which is located on the side where the loop-shaped conductor 22 is biased and where the space on the tag is relatively small, is illustrated as having a configuration including a first wire portion 231 and a second wire portion 232, but the configuration of the antenna portion 23A is not limited to this. The antenna portion 23A only needs to be formed to satisfy the requirement that the maximum length of the current path be equal to the length of the current path of the antenna portion 23B in the longitudinal direction (X direction). For example, the antenna portion 23A may be formed in a meandering shape, thereby increasing the maximum length of the current path.

[0047] Furthermore, if the antenna portion is formed large relative to the longitudinal and lateral directions of the RFID tag, when multiple RFID tags are stacked and placed close to each other, the antenna portions of the tags may interfere with each other's communication with the external communication device, hindering communication. In other words, there is a risk that the stackability of the RFID tags may be reduced. This problem is particularly noticeable in the antenna portion 23B, which has a larger area, in the antenna pattern of this embodiment.

[0048] Therefore, in this embodiment, an opening 237 is provided in the widened portion 235 of the antenna portion 23B by hollowing out the center portion. With this configuration, even when multiple RFID tags are stacked and close to each other, when the antenna portion 23B of any tag communicates with an external communication device, the communication can be carried out via the opening 237 of the antenna portion 23B of another tag located between them. This makes it possible to preferably prevent the antenna portions 23B of other tags from interfering with each other and hindering communication, thereby preventing a decrease in the stackability of the RFID tag 1.

[0049] In this way, even if the RFID tag 1 of this embodiment is configured so that the loop-shaped conductor 22 is biased toward the positive X-direction side relative to the center of the inlay 2 in the X-direction, it is possible to suppress a decrease in communication performance and also a decrease in stackability.

[0050] Furthermore, the connection part 234 of the antenna part 23B has, at least in a part of the longitudinal direction (X direction) of the tag, a constant width part 238 that has a predetermined width in the longitudinal direction and extends in the lateral direction (Y direction) of the tag. This configuration makes it possible to prevent disconnection of the connection part 234 and to more reliably connect the antenna part 23B to the loop conductor 22.

[0051] 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 example of dimensions shown in Fig. 3, all of the conditions regarding the shapes of the loop conductor 22 and the antenna parts 23A and 23B described above are satisfied.

[0052] 1, in the RFID tag 1 of this embodiment, a label paper (film-based tack paper) 3 is further disposed above the inlay 2. The label paper 3 is printable on the surface on the positive side of the Z axis. The material of the label paper 3 can be selected as appropriate, and materials other than paper, such as resin materials, may be used as long as they are printable.

[0053] The label paper 3 is also formed with a larger dimension in the X direction than the inlay 2, with the inlay 2 located in its center and excess portions on both sides in the X direction that do not overlap with the inlay 2. An adhesive portion 4 having adhesiveness is provided on the back surface of this excess portion on the negative side of the Z axis, on the surface that comes into contact with the object to which it is to be affixed (the lower surface in Figure 1). In this way, the inlay 2 and the adhesive portion 4 are arranged so as not to overlap in a plan view. In the example of Figure 1, a pair of adhesive portions 4A, 4B are arranged on the positive and negative sides of the X axis relative to the inlay 2.

[0054] The adhesive portion 4 comes into contact with the object to be affixed and adheres to the object by its adhesive force, thereby affixing the entire RFID tag 1 to the object to be affixed.

[0055] The adhesive portion 4 is preferably formed, for example, from an adhesive hot melt. Hot melt is a thermoplastic adhesive that is solid at room temperature but liquefies when heated and melted, and is applied to an adherend, where it forms a bond by cooling and solidifying. An adhesive hot melt is one that retains adhesive strength on the exposed surface even after cooling and solidifying. The adhesive portion 4 is preferably formed using biological resources (biomass) or biodegradable materials. The biomass content of the adhesive portion 4 is, for example, 25%.

[0056] Additionally, a bonding portion 5 is laminated on the back surface of the label paper 3 on the negative side of the Z axis. The bonding portion 5 is bonded to the top surface of the inlay 2 and the top surface of the adhesive portion 4, thereby covering the inlay 2 and the adhesive portion 4 with the label paper 3. Furthermore, when laminated, the bonding portion 5 can penetrate into the gap formed by the inlay 2 and the label paper 3 above it and fill this gap.

[0057] The joints 5 are preferably formed using, for example, a non-adhesive hot melt adhesive. A non-adhesive hot melt adhesive has no adhesive strength on the exposed surface after cooling and solidifying. As with the adhesive parts 4, the joints 5 are preferably formed using biological resources (biomass) or biodegradable materials.

[0058] Before use, the RFID tag 1 has a release paper 6 disposed below the adhesive portion 4. The release paper 6 is formed, for example, to be the same size as or larger than the label paper 3, and the label paper 3 and the release paper 6 are tightly attached by the adhesive portion 4. This prevents the pair of adhesive portions 4A, 4B on both sides of the label paper 3 in the X direction from being exposed to the outside before being used to attach the RFID tag 1 to an object, thereby maintaining adhesive strength. When the RFID tag 1 is used, the release paper 6 is peeled off from the RFID tag 1, and the exposed adhesive portions 4A, 4B of the label paper 3 allow the RFID tag 1 to be attached to an object.

[0059] 1, and a plurality of RFID tags 1 may be arranged on one sheet of release paper 6. This can improve manufacturing efficiency and transport efficiency.

[0060] The thickness of the RFID tag 1 in the Z direction (excluding the release paper 6) of this embodiment is 80 μm to 260 μm, preferably 150 to 230 μm. The thickness of the adhesive portion 4 in the Z direction is preferably about 10 μm to 30 μm.

[0061] 1 and 2, a pair of adhesive portions 4A, 4B are arranged on the positive and negative sides of the X axis relative to the inlay 2. With this arrangement, the inlay 2 itself is not directly attached to the object to which it is to be attached, but is indirectly attached to the object via the adhesive portion 4.

[0062] 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 be the same size as the inlay 2. In this case, since the outer edge of the label paper 3 cannot come into contact with the object to be affixed, the adhesive portion 4 is provided on the entire lower surface of the base material 24 of the inlay 2 that faces the object to be affixed, and the inlay 2 is directly affixed to the object to be affixed. Furthermore, in the configuration shown in Fig. 1, a continuous adhesive portion may be provided between the pair of adhesive portions 4A, 4B to form a single adhesive layer. In this case, the inlay 2 is also directly affixed to the object to be affixed.

[0063] The RFID tag 1 may also be configured such that elements such as a magnetic sheet, a spacer layer, and a dielectric layer are further laminated on the side of the inlay 2 facing the object to which it is to be affixed (the lower side in FIG. 1 ). The magnetic sheet is a sheet material containing a magnetic material, and is preferably one that has excellent magnetic shielding properties against radio waves in the frequency band (e.g., the UHF band) used to read the IC chip 21. The spacer layer is an element that positions the inlay 2 at a distance of its thickness from the object to which it is to be affixed, and is preferably formed of an insulator such as, for example, cardboard, woven or nonwoven fabric made of fibers such as synthetic resin, or a sheet of inorganic material such as ceramic glass. The dielectric layer is preferably formed of an insulator material with a relative permittivity of approximately 1.2 to 3.0, which increases the communication distance of the RFID tag 1.

[0064] <Modifications> Modifications of the RFID tag according to the first embodiment will be described with reference to Fig. 4 to Fig. 6. Fig. 4 is a plan view of an RFID tag 1A according to the first modification. The outline of Fig. 4 and Figs. 5 and 6 described below are similar to Fig. 2.

[0065] 4 differs from the RFID tag 1 of this embodiment in that the connection portion 234 does not have a constant-width portion 238. The antenna pattern of the RFID tag 1A of the first modification can also achieve the same effects as the RFID tag 1 of this embodiment.

[0066] Fig. 5 is a plan view of an RFID tag 1B according to a second modification. In the RFID tag 1B according to the second modification shown in Fig. 5, the shapes of a connection portion 234B and an expanded width portion 235B of an antenna portion 23B are different from those of the connection portion 234 and the expanded width portion 235 of the present embodiment.

[0067] In RFID tag 1B, one side 222 on the Y-negative side of a pair of opposite sides of rectangular loop conductor 22 that extend in the X-direction and are arranged opposite each other in the Y-direction is located near the end on the Y-negative side of the tag's short-side direction. Similarly, one side 236B1 on the Y-negative side of a pair of opposite sides of rectangular portion 236B of antenna unit 23B that extend in the X-direction and are arranged opposite each other in the Y-direction is located near the end on the Y-negative side of the tag's short-side direction. These sides 222, 236B1 are located on the same straight line along the X-direction at the same position in the tag's short-side direction (Y-direction).

[0068] Unlike the widening portion 235 of this embodiment, the trapezoidal shape of the widening portion 235B is not formed in a shape that is line-symmetrical with respect to the second imaginary line VS. The trapezoidal shape of the widening portion 235B has a pair of line segments connecting the upper and lower sides that are different in length. One line segment 235B1 connecting the Y-positive ends of the upper and lower sides is a hypotenuse that slopes toward the Y-negative direction as it moves toward the X-positive direction. Meanwhile, the other line segment 235B2 connecting the Y-negative ends of the upper and lower sides is a line segment parallel to the X direction. This other line segment 235B2 is also arranged in the same position in the short-side direction (Y direction) of the tag, on the same straight line along the X direction, as the Y-negative side 222 of the loop-shaped conductor 22 and the Y-negative side 236B1 of the rectangular portion 236B.

[0069] The opening 237B is also formed in a trapezoidal shape similar to the widened portion 235B, so that the widened portion 235B is formed such that a portion corresponding to a pair of line segments of the trapezoid extends in the X direction with equal width.

[0070] The connection portion 234B has a first linear portion 234B1 extending further in the X-positive direction from a portion corresponding to a line segment 235B1 connecting the Y-positive ends of the upper and lower sides of the pair of trapezoidal line segments of the widened portion 235B, and a second linear portion 234B2 extending further in the X-positive direction from a portion corresponding to a line segment 235B2 connecting the Y-negative ends of the upper and lower sides of the pair of trapezoidal line segments of the widened portion 235B. The first linear portion 234B1 and the second linear portion 234B2 are connected at their X-positive ends to the opposite side portion 221B of the loop-shaped conductor 22.

[0071] The equal width portion 238B is formed so as to extend in the short direction with a predetermined width in the longitudinal direction of the tag (X direction) between the first linear portion 234B1 and the second linear portion 234B2 of the connection portion 234B in at least a part of the longitudinal direction, connecting the two.

[0072] Fig. 6 is a plan view of an RFID tag 1C according to a third modified example. In the RFID tag 1C of the third modified example shown in Fig. 6, the shape of a connecting portion 234C is different from that of the connecting portion 234B of the second modified example.

[0073] Like the connecting portion 234B of the second modified example, the connecting portion 234C has a shape in which both ends in the Y direction linearly extend from a pair of trapezoidal line segments 235C1, 235C2 of the widened portion 235C, but is formed into an integral rectangular shape without any openings. In other words, the shape of the connecting portion 234C is equivalent to the connecting portion 234B of the second modified example, in which the equal-width portion 238B is formed to connect the first linear portion 234B1 and the second linear portion 234B2 of the connecting portion 234B along the entire tag longitudinal direction (X direction) of the connecting portion 234B. In other words, the connecting portion 234C of the third modified example also has the function of the equal-width portion 238 of this embodiment and the equal-width portion 238B of the second modified example.

[0074] <Communication Performance Test of RFID Tag> A communication performance test was conducted using the RFID tag 1 of this embodiment, the RFID tag 1B of the second modified example, and the RFID tag 1C of the third modified example.

[0075] RFID tags 1, 1B, and 1C were placed on a flat surface, and a test was conducted to read information from each tag using a horizontally positioned antenna. RFID tags 1, 1B, and 1C were oriented so that the long side of each tag faced the antenna. A Voyantic Tagformance Pro was used as the measuring device including the antenna.

[0076] Under these conditions, the frequency characteristics of the RFID tags 1, 1B, and 1C were measured. The measurement frequency band of the radio waves for wireless communication during measurement was 800 to 1000 MHz, and the EIRP (Equivalent Isotropically Radiated Power) was 3.28 W.

[0077] 7A and 7B are diagrams showing the frequency characteristics of RFID tags 1, 1B, and 1C measured in a communication performance test. Fig. 7A shows the frequency characteristics of RFID tag 1 of this embodiment, Fig. 7B shows the frequency characteristics of RFID tag 1B of the second modified example, and Fig. 7C shows the frequency characteristics of RFID tag 1C of the third modified example. In each diagram, the horizontal axis represents the frequency (MHz) of the radio wave for wireless communication, and the vertical axis represents the communicable distance (m) from each RFID tag to the antenna.

[0078] In each diagram in Fig. 7, the predetermined frequency of 920 MHz, which is included in the UHF band, is indicated by a thick dotted line. As shown in Fig. 7, it was confirmed that the peak of the frequency characteristics can be maintained near 920 MHz by using the antenna patterns of the RFID tag 1 of this embodiment, the RFID tag 1B of the second modified example, and the RFID tag 1C of the third modified example. This shows that even with an antenna pattern in which the loop conductor 22 is biased relative to the center of the inlay 2 in the longitudinal direction (X direction), a decrease in communication performance can be suppressed.

[0079] Second Embodiment Fig. 8 is a plan view of a tag 10 according to a second embodiment. In the example of Fig. 8, the tag 10 incorporates the RFID tag 1 of the first embodiment.

[0080] Product information 11 and a barcode 12 relating to the product to which the tag 10 is attached are printed on the surface of the tag 10. The product information 11 includes information such as the product name, size, and price, as shown in Fig. 8. Information similar to the product information 11 is recorded in an IC chip 21 mounted on the inlay 2 of the RFID tag 1 built into the tag 10. The barcode 12 also includes information corresponding to the product information 11.

[0081] When a reading device such as an RFID reader is used, product information regarding the product to which the tag 10 is attached can be read from the internal RFID tag 1. Also, when a reading device such as a barcode reader is used, product information regarding the product to which the tag 10 is attached can be read from the barcode 12 printed on the surface of the tag 10.

[0082] The barcode 12 may be any identifier that includes information corresponding to the product information 11, and may be replaced with another identifier such as a two-dimensional code.

[0083] The tag 10 also has a perforation 13. The perforation 13 is provided at a position that intersects with the constant width portion 238 of the antenna portion 23B of the RFID tag 1. In the example of Fig. 8, the perforation 13 is arranged at a position that overlaps the entire area of ​​the constant width portion 238 along the Y direction, and is arranged parallel to the Y direction. The perforation 13 separates the tag 10 into a base portion 14, in which a hole 16 is provided through which a string or the like is passed, and a tip portion 15.

[0084] As shown in FIG. 8A, when the base 14 and tip 15 of the tag 10 are connected via the perforation 13, information can be read from the RFID tag 1 embedded in the tag 10.

[0085] 8(B), when the tag 10 is torn at the perforation 13 and the tip portion 15 is separated from the base portion 14, the inlay 2 of the RFID tag 1 built into the tag 10 is severed at the perforation 13. As described above, the perforation 13 is located at a position intersecting the constant-width portion 238 of the antenna portion 23B, so that the IC chip 21, the loop conductor 22, and one of the antenna portions 23A are all contained in the severed tip portion 15. Furthermore, with regard to the other antenna portion 23B, only the portion of the connection portion 234 extending in the X direction from the boundary with the opposite side 221A of the loop conductor 22 to the perforation 13 remains inside the severed tip portion 15. In other words, a portion of the other antenna portion 23B of the pair of antenna portions located on the negative X side of the loop conductor 22 (i.e., the portion of the connection portion 234 located on the positive X side of the perforation 13 of the constant-width portion 238) remains.

[0086] Therefore, after cutting, the tip 15 of the tag 10 contains the IC chip 21 of the RFID tag 1, the loop conductor 22, and a pair of antennas disposed on both sides of the loop conductor 22 in the X direction. Therefore, although the communication performance is naturally inferior to that of the RFID tag 1 before cutting, the tip 15 alone after cutting can maintain communication transmission of the inlay 2, making it possible to read information from the RFID tag 1.

[0087] In a configuration in which the IC chip 21 and the loop conductor 22 are located in the center of the tag's longitudinal direction (X direction), as in conventional RFID tags, if the tag function is to be retained in the tip portion 15 of the tag 10 after cutting, as in this embodiment, the perforation 13 of the tag 10 must be located on the negative X side of the center of the tag's longitudinal direction. Therefore, the tip portion 15 of the tag 10 that is cut and separated has a larger area than the base portion 14. This configuration is thought to make it difficult to tear the tip portion 15 from the base portion 14. Furthermore, when the tag 10 is a price tag, for example, the tip portion 15 after cutting can be stored in a store or the like for product management purposes, but if the tip portion 15 becomes large, management may become more complicated.

[0088] To address this problem, by configuring the RFID tag 1 of the first embodiment to be built into the tag 10, the loop conductor 22 is positioned offset to one side (the positive X side in the examples of FIGS. 2 and 8 ) from the center in the longitudinal direction (X direction) of the RFID tag 1, and by building the offset side into the tip portion 15, the tip portion 15 can be made smaller than the base portion 14. This allows the tip portion 15 to be easily handled while still maintaining communication and transmission capabilities of the inlay 2 with just the tip portion 15 after separation.

[0089] Furthermore, in the second embodiment, in a configuration in which the RFID tag 1 of the first embodiment is built into a tag 10, the perforation 13 is provided at a position intersecting the constant-width portion 238 of the antenna portion 23B of the RFID tag 1. Generally, the perforation 13 of the tag 10 is formed by cutting a slit through the RFID tag 1 and the components of the tag 10, such as a pair of paper pieces sandwiching the RFID tag 1 from both sides in the Z direction, after the RFID tag 1 is installed inside the tag 10. In other words, when the perforation 13 is formed, a portion of the antenna pattern of the RFID tag 1 is also cut. Here, the constant-width portion 238 is a portion formed with a predetermined length in the short direction (Y direction) of the tag 1 and the tag 10. Therefore, by arranging the perforation 13 at a position overlapping the constant-width portion 238, it is possible to prevent the antenna portion 23B from being completely severed when the perforation 13 is formed.

[0090] In order to ensure the above-mentioned effect, it is necessary to set the relationship in shape between the perforation 13 and the equal-width portion 238 so that the pitch (length of the cut portion) of the perforation 13 is shorter than the Y-direction dimension of the equal-width portion 238.

[0091] Furthermore, since the equal width portion 238 is a portion formed with a constant width dimension in the longitudinal direction (X direction) of the tag 1 and the tag 10, even if there is a deviation in the relative positional relationship between the perforation 13 and the RFID tag 1 within the range of the width dimension of the equal width portion 238, the perforation 13 can be formed on the equal width portion 238. Therefore, since a deviation in the relative positional relationship between the perforation 13 and the RFID tag 1 can be tolerated within the range of the width dimension of the equal width portion 238, the manufacturing precision of the tag 10 incorporating the RFID tag 1 can be relaxed.

[0092] Note that the RFID tag 1B of the second modified example described with reference to FIG. 5 also has a constant-width portion 238B in the connection portion 234B, similar to the RFID tag 1 of the first embodiment, and the RFID tag 1C of the third modified example described with reference to FIG. 6 also has the entire connection portion 234C function as the widening portion, so these tags 1B and 1C may be configured to be built into the tag 10. When the RFID tag 1B of the second modified example is built into the tag 10, the perforation 13 may be provided at a position intersecting the constant-width portion 238B of the antenna portion 23B of the RFID tag 1B. When the RFID tag 1C of the third modified example is built into the tag 10, the perforation 13 may be provided at a position intersecting the connection portion 234C of the antenna portion 23B of the RFID tag 1C. These configurations can achieve the same effects as the configuration in which the RFID tag 1 of the first embodiment is built into the tag 10.

[0093] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise.

[0094] This international application claims priority based on Japanese Patent Application No. 2024-145646 filed on August 27, 2024, the entire contents of which are incorporated herein by reference.

[0095] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C RFID tag 21 IC chip 22 Loop-shaped conductor 221A, 221B Pair of opposite sides 23A Antenna section (first antenna section) 231 First line section 232 Second line section 23B Antenna section (second antenna section) 234, 234B, 234C Connection section 235, 235B, 235C Widened section 236, 236B, 236C Rectangular section 237, 237B, 237C Opening 238, 238B Equal width section 10 Hang tag 13 Perforation

Claims

1. An RFID tag comprising: an IC chip on which identification information is recorded; a loop-shaped conductor connected to the IC chip, extending in the short direction of the RFID tag and formed in an annular shape with a pair of opposite sides arranged opposite both ends in the long direction; a first antenna portion extending from one of the pair of opposite sides to one side in the long direction; and a second antenna portion extending from the other of the pair of opposite sides to the other side in the long direction, wherein the loop-shaped conductor is arranged biased toward the first antenna portion from the center in the long direction, and the second antenna portion has: a connection portion connected to the loop-shaped conductor; an expanded portion connected to the connection portion on the opposite side of the loop-shaped conductor in the long direction and formed so that the dimension in the short direction increases with increasing distance from the connection portion along the long direction; and a rectangular portion connected to the expanded portion on the opposite side of the connection portion in the long direction and formed in a rectangular shape, wherein the expanded portion has an opening formed by hollowing out a center portion, an RFID tag, wherein the first antenna unit is formed so that a maximum length of a current path thereof is equal to a length in the longitudinal direction of a current path of the second antenna unit; 2. The RFID tag according to claim 1, wherein the first antenna portion comprises: a first wire portion connected to the loop-shaped conductor and extending along the longitudinal direction to the vicinity of one end of the RFID tag in the longitudinal direction; and a second wire portion extending from the end of the first wire portion along the lateral direction to the vicinity of the end of the RFID tag in the lateral direction.

3. The RFID tag according to claim 1, wherein the connecting portion has, in at least a portion in the longitudinal direction, a constant width portion that has a predetermined width in the longitudinal direction and extends in the lateral direction.

4. A tag to which the RFID tag according to claim 3 is attached, the tag having a perforation provided at a position intersecting the equal width portion of the RFID tag.

Images