JP2011253362A - Ic tag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an IC tag capable of being downsized with a simple structure and lengthening a communication distance between itself and a reader/writer.SOLUTION: An IC tag includes a magnetic core 6, an IC tag circuit 1a including a first antenna 2a wound around the outer periphery of the magnetic core 6 and an IC chip 3 connected to the first antenna 2a, and a first resonance circuit 1b including a second antenna 2b spaced from the first antenna 2a and wound around the outer periphery of the magnetic core 6 and a first capacitor 4b connected to the second antenna 2b.

Description

  The present invention relates to an IC tag using RFID (Radio Frequency Identification) technology for reading and writing information without contact.

  In recent years, IC tags using RFID technology have been used in various fields. Communication is possible between an IC tag and a reader / writer that reads and writes information, and it has come to be used in fields such as logistics management, process management, and traceability of foods. As security devices, IC tags are also used for anti-counterfeiting and tamper-proof labels.

  These IC tags are known in which an antenna is formed by etching a copper foil or an aluminum foil bonded to a base film, and an IC chip for a non-contact IC tag is connected. Alternatively, an antenna may be formed by spirally winding a copper wire such as an enameled wire having an insulating film on the surface, and an IC chip for a non-contact IC tag is connected. These IC tags are sandwiched between thick films and bonded together by thermocompression bonding and processed into cards, or adhesive sheets are pasted into labels to be used as membership cards and student ID cards. Used in various fields.

  Basically, the communication distance of an IC tag that operates in the 125 KHz band or 13.56 MHz band electromagnetic induction system depends largely on the antenna opening area (coil winding diameter). That is, the larger the antenna opening area, the longer the communication distance, and the smaller the antenna opening area, the shorter the communication distance. In order to increase the communication distance, it is necessary to increase the opening area of the antenna. However, it is difficult to reduce the size of the IC tag by increasing the opening area of the antenna.

  As an IC tag that can improve communication performance even when the antenna opening area is small, for example, Patent Document 1 discloses a magnetic core formed in a rod shape, a coil wound around the magnetic core, and a coil. An RFID tag is described that includes an electrically connected IC chip and a housing that houses a magnetic core, a coil, and the IC chip. According to Patent Document 1, it is described that by providing a magnetic core formed in a rod shape, the magnetic flux density can be increased, the size can be reduced, and it can be easily mounted on various electronic devices regardless of the shape.

JP 2009-237795 A

  However, in Patent Document 1, one end of a magnetic core around which a coil is wound is connected to an IC chip through a base having a complicated shape, and the other end of the magnetic core is connected to a frequency adjustment core with a screw or the like. . Therefore, the configuration is complicated, the number of parts is increased, and the assembly is complicated.

  In some applications, it may be desired to further increase the communication distance. For example, when IC tags are used for managing roads and tunnels, when IC tags are embedded by opening holes in roads and tunnels, IC tags can be placed within limited dimensions. Although it is necessary to embed, since the opening area of the antenna is limited, the communication distance is also limited.

  In view of the above problems, the present invention provides an IC tag that can be reduced in size with a simple configuration and can increase the communication distance between the IC tag and a reader / writer.

  In order to solve the above-mentioned problems, the present inventor has intensively studied, and by setting the configuration and arrangement relationship of the magnetic body, the IC tag circuit, and the resonance circuit to appropriate conditions, even if the IC tag cannot be enlarged, The present inventors have found an IC tag that can increase the communication distance between an IC tag and a reader / writer and that can simplify and downsize components.

  The present invention completed on the basis of the above knowledge, in one aspect, an IC tag circuit including a magnetic core, a first antenna wound around the outer periphery of the magnetic core, and an IC chip connected to the first antenna; An IC tag including a second antenna that is spaced from the first antenna and wound around the outer periphery of the magnetic core, and a first resonance circuit that includes a first capacitor connected to the second antenna. .

  In one embodiment of the IC tag according to the present invention, the IC tag circuit further includes a second capacitor connected to the first antenna.

  In one embodiment of the IC tag according to the present invention, the difference between the resonance frequency of the single IC tag circuit and the resonance frequency of the first single resonance circuit is within 2 MHz.

  In one embodiment of the IC tag according to the present invention, the magnetic core has a hollow structure, and the IC chip and the first capacitor are accommodated in the hollow structure.

  In one embodiment of the IC tag according to the present invention, the magnetic core includes that one magnetic sheet is rolled into a cylindrical shape.

  In one embodiment of the IC tag according to the present invention, the first antenna and the second antenna are separated by 2 to 5 mm.

  In one embodiment of the IC tag according to the present invention, the number of turns of the first antenna and the second antenna is 2 to 4 turns.

  In one embodiment of the IC tag according to the present invention, the third capacitor is separated from the first and second antennas and is wound around the outer periphery of the magnetic core and is connected to the third antenna. A second resonance circuit including

  According to the present invention, it is possible to provide an IC tag that can be downsized with a simple configuration and that can increase the communication distance between the IC tag and the reader / writer.

FIG. 1 is a schematic diagram illustrating an example of an IC tag according to the first embodiment. FIG. 2 is a schematic diagram illustrating an example of an IC tag according to the second embodiment. FIG. 3 is a schematic diagram illustrating an example of an IC tag according to the third embodiment. FIG. 4A is a schematic diagram showing an example of an IC tag according to a modification of the first embodiment, and FIG. 4B is a schematic diagram showing a state in which the substrate is housed inside the magnetic core. It is. FIG. 5A is a schematic diagram illustrating an example of an IC tag according to a modification of the second embodiment, and FIG. 5B is a schematic diagram illustrating a state in which the substrate is housed inside the magnetic core. It is. FIG. 6A is a schematic diagram illustrating an example of an IC tag according to a modification of the third embodiment, and FIG. 6B is a schematic diagram illustrating a state in which the substrate is housed inside the magnetic core. It is.

  Hereinafter, first to third embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. The first to third embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is the structure of component parts, The arrangement is not specified as follows.

(First embodiment)
As shown in FIG. 1, the IC tag according to the first embodiment is connected to the magnetic core 6, the first antenna 2a wound around the outer periphery of the magnetic core 6, and the first antenna 2a. The IC tag circuit 1 a including the IC chip 3 and the first antenna 2 b that is separated from the first antenna 2 a and is wound around the outer periphery of the magnetic core 6 and connected to the second antenna 2 b And a first resonance circuit 1b including a capacitor 4b.

  The magnetic core 6 has a hollow structure formed in a circular cylindrical shape. The shape of the magnetic core 6 is not limited to a circular cylindrical shape, and may be a triangular, quadrangular, or other polygonal cylindrical shape. A rod-like or cylindrical structure may be used. The magnetic core 6 may be made of permalloy powder, sendust powder, soft ferrite, or other magnetic powder molded with a resin such as plastic as a binder, but is not limited thereto. From the viewpoint of weight reduction, the magnetic core 6 can be a cylindrical body obtained by rolling a single magnetic sheet into a cylindrical shape. The magnetic core 6 may be a laminated body made up of a plurality of magnetic sheets.

  The first antenna 2 a and the second antenna 2 b are wound around the outer periphery of the magnetic core 6. The shapes of the first antenna 2 a and the second antenna 2 b may be a circle, a triangle, a quadrangle, or a polygon according to the shape of the magnetic core 6. The material of the first antenna 2a and the second antenna 2b is preferably, for example, a copper wire whose surface is insulated with a film such as an enamel wire or a polyurethane wire. Alternatively, a self-bonding wire in which a film that is fused with hot air or alcohol or the like is provided on the insulating film may be used. A polyester-based resin or a polyamide-based resin can be used as the self-bonding wire. In the resonance circuit, the lower the resistance, the better the performance. Therefore, the diameters of the copper wires of the first antenna 2a and the second antenna 2b are preferably, for example, φ0.1 to φ1.0 mm, and more preferably. Is φ0.5 to φ1.0 mm.

  As the IC chip 3, the IC chip 3 for an IC tag that operates in an electromagnetic induction system of 125 KHz band or 13.56 MHz band is used, but the type of the IC chip 3 is not particularly limited. As for the connection between the first antenna 2a and the IC chip 3, the terminal of the IC chip 3 and the first antenna 2a may be directly connected. However, as shown in FIG. After mounting the chip 3, the substrate 7 and the first antenna 2a may be connected. As a method for mounting the IC chip 3 on the substrate 7, connection by wire bonding or thermocompression bonding using an anisotropic conductive material such as anisotropic conductive paste (ACP) or anisotropic conductive film (ACF) is used. Connection, soldering or ultrasonic connection is available.

  As the first capacitor 4b, a ceramic capacitor, an electrolytic capacitor, or the like is used, but the type of the capacitor is not particularly limited. As for the connection between the second antenna 2b and the first capacitor 4b, the terminal of the first capacitor 4b and the second antenna 2b may be directly connected. However, as shown in FIG. After mounting the capacitor 4b on the substrate 7, the first capacitor 4b and the second antenna 2b may be connected. As a method of mounting the first capacitor 4b on the substrate 7, for example, connection by soldering or ultrasonic waves can be used. The capacity of the first capacitor 4b can be set according to the diameter and the number of turns of the second antenna 2b.

  The resonance frequency of the IC tag depends on the influence of the magnetic core 6 and the amplification effect of the IC tag circuit 1a and the first resonance circuit 1b. It becomes lower than the resonance frequency. Therefore, it is preferable to set the resonance frequency of each of the IC tag circuit 1a and the first resonance circuit 1b higher than the target resonance frequency (target resonance frequency). For example, when an IC tag having a target resonance frequency of 13.56 MHz is manufactured using the first and second antennas 2a and 2b (with a copper wire diameter of φ0.5 mm) having an inner diameter of φ15 mm, It is preferable to set the resonance frequency of each of the single resonance circuits 1b in the vicinity of 20 to 26 MHz. When the IC tag circuit 1a and the first resonance circuit 1b are arranged adjacent to each other and the IC tag according to this embodiment is assembled, the target resonance frequency of around 13.56 MHz is realized. In this case, for example, the number of turns of the first antenna 2a and the second antenna 2b is about 8 to 10 turns, and the capacity of the first capacitor 4b connected to the second antenna 2b is the first antenna 2a. Can be matched to the capacity of the IC chip 3 to be connected. For example, if the IC chip 3 has a capacitance of 30 pF, the first capacitor 4b can have a capacitance of around 30 pF.

  It is better to set the resonance frequency when the IC tag circuit 1a and the first resonance circuit 1b are each single to some extent. If the resonance frequency when the IC tag circuit 1a and the first resonance circuit 1b are each separated from each other, when the IC tag according to the present embodiment is assembled, two resonance frequency peaks are generated and amplified. The effect may be reduced. For example, when an IC tag having an inner diameter of the first and second antennas 2a and 2b of φ15 mm (with a copper wire diameter of φ0.5 mm) and a target resonance frequency of 13.56 MHz is manufactured, the resonance frequency of the IC tag circuit 1a is set to When the IC tag according to this embodiment is assembled by setting the resonance frequency of the first resonance circuit 1b to 21.20 MHz with 27.58 MHz, two resonance frequency peaks are confirmed, and the amplification effect is also reduced. It was confirmed that

  According to the study by the present inventors, if the difference in resonance frequency between the IC tag circuit 1a and the first resonance circuit 1b is about 2 MHz, two peaks of the resonance frequency are not confirmed. I understood. Therefore, the difference between the resonance frequency of the IC tag circuit 1a alone and the resonance frequency of the first resonance circuit 1b alone is realized by arranging the IC tag circuit 1a alone and the first resonance circuit 1b alone. It is preferable to set the frequency to be within 15% (22.10 to 24.10 MHz), more preferably within 10% (22.05 to 23.05 MHz) with respect to the target resonance frequency (for example, 13.56 MHz).

  According to the IC tag according to the first embodiment, the effect of converging the magnetic flux is enhanced by winding the antenna around the magnetic core 6, and the Q value is higher than that of a normal IC tag including only the antenna and the IC chip. The communication distance increases. Further, by winding the second antenna 2b around the magnetic core 6 in the vicinity of the IC tag circuit 1a, the Q value is further increased due to the amplification effect of the IC tag circuit 1a and the first resonance circuit 1b. The communication distance between the IC tag and the reader / writer becomes longer. Further, by integrating the first and second antennas 2a and 2b, the IC chip 3, and the first capacitor 4b on the outer periphery of the magnetic core 6, the size can be reduced with a simple configuration. Furthermore, by arranging the first antenna 2a and the second antenna 2b in a three-dimensional manner, the resonance frequency can be adjusted only by changing the arrangement interval, compared with a conventional IC tag arranged in two dimensions. Can be downsized.

(Second Embodiment)
As shown in FIG. 2, the IC tag according to the second embodiment includes an IC tag circuit 1d that further includes a second capacitor 4a connected to the first antenna 2a. Different from tag.

  The second capacitor 4a is for adjusting the resonance frequency of the IC tag circuit 1d, and at the same time, adjusts the balance between the inductance and capacitance of the IC tag circuit 1d, and increases the Q value of the IC tag circuit 1d itself. Is. For example, when an IC tag having an inner diameter of the first and second antennas 2a and 2b of φ15 mm (with a copper wire diameter of φ0.5 mm) and a target resonance frequency of 13.56 MHz is manufactured, the IC tag circuit 1d and the first antenna When the resonance frequency of each of the resonance circuits 1b is set to approximately the same resonance frequency in the vicinity of 20 to 26 MHz and the IC tag according to the present embodiment is assembled, the target resonance frequency of around 13.56 MHz is realized. Can be. In this case, the number of turns of the first antenna 2a and the second antenna 2b is about 2 to 4 turns. The capacity of the first capacitor 4b connected to the second antenna 2b is preferably matched with the capacity of the IC chip 3 and the second capacitor 4a connected to the first antenna 2a. For example, if the IC chip 3 has a capacitance of 30 pF and the second capacitor 4a has a capacitance of 330 pF, the first capacitor 4b can have a capacitance of around 360 pF. If there is no capacitor near 360 pF, a plurality of capacitors may be connected in parallel so that the total capacitance is around 360 pF. Also in this case, it is preferable to set the resonance frequency when the IC tag circuit 1d and the resonance circuit (1b) are each single so that the same numerical value can be obtained to some extent.

  Depending on the balance between the number of turns of the antenna (inductance L) and the capacitance C, the amplitude of the resonance waveform changes. In order to increase the communication distance, it is preferable to set the amplitude of the resonance waveform to be large. Table 1 shows the relationship among the number of antenna turns, the capacitance of the capacitor and the IC chip, the resonance frequency of the IC tag, and the amplitude of the resonance waveform when the IC tag according to the second embodiment is manufactured. When the antennas 2a and 2b having an inner diameter of φ15 mm are used as the first and second antennas 2a and 2b (with a copper wire diameter of φ0.5 mm), the number of turns of the antenna is three turns rather than four turns, and three turns. It has been found that the two-turn winding increases the amplitude of the resonance waveform of the IC tag circuit 1d (the Q value increases) and improves the communication performance. Therefore, in the IC tag according to the second embodiment, the number of turns of the first and second antennas 2a and 2b is set to 2 to 4 turns, more preferably 2 to 3 turns, and further preferably 2 turns. it can.

  The resonance frequency also changes depending on the arrangement interval on the magnetic core 6 between the IC tag circuit 1d and the first resonance circuit 1b. Therefore, it is preferable to set the interval between the IC tag circuit 1d and the first resonance circuit 1b in accordance with the target resonance frequency. Table 2 shows the relationship between the resonance frequency and the amplitude of the resonance waveform with respect to the antenna interval between the first antenna 2a and the second antenna 2b. It can be seen that the resonance frequency tends to gradually decrease as the distance between the IC tag circuit 1d and the first resonance circuit 1b decreases. On the other hand, the amplitude of the resonance waveform gradually increases as the distance between the antennas is increased. In the IC tag according to the second embodiment, the first antenna 2a and the second antenna 2b are preferably separated from each other by 2 to 5 mm (13 to 33% with respect to the inner diameter of the antenna), more preferably 4 -5 mm, more preferably 4.5 mm.

  According to the IC tag according to the second embodiment, by connecting the second capacitor 4a to the first antenna 2a, the resonance frequency of the IC tag circuit 1d is adjusted, and at the same time, the inductance of the IC tag circuit 1d and The balance of the capacitance can be adjusted, and the Q value of the IC tag circuit 1d itself can be increased. As a result, the communication distance can be extended within a limited range of the antenna size, so even if the size of the IC tag (antenna opening area) cannot be increased, the IC tag and the reader / writer are not connected. The communication distance can be increased and can be developed for various applications.

(Third embodiment)
As shown in FIG. 3, the IC tag according to the third embodiment is separated from the first and second antennas 2a and 2b, and the third antenna 2c wound around the outer periphery of the magnetic core 6 and An IC tag circuit 1d further including a second resonance circuit 1c including a third capacitor 4c connected to the third antenna 2c, and further including a second capacitor 4a connected to the first antenna 2a and the IC chip 3. 1 is different from the IC tag shown in FIG.

  According to the IC tag shown in FIG. 3, the amplification effect of each circuit of the IC tag circuit 1d, the first resonance circuit 1b, and the second resonance circuit 1c is further increased, the Q value is increased, and the communication distance is further increased. be able to. For example, when an IC tag having an inner diameter of the first and second antennas 2a and 2b of φ15 mm (a copper wire diameter of φ0.5 mm) and a target resonance frequency of 13.56 MHz is manufactured, the IC tag circuit 1d and the first antenna The resonance frequency when each of the resonance circuit 1b and the second resonance circuit 1c is single is set to substantially the same resonance frequency around 20 to 26 MHz. And when the IC tag which concerns on 3rd Embodiment is assembled, it is preferable to implement | achieve the 13.56 MHz vicinity of the target resonant frequency.

  In addition, while the 2nd resonant circuit 1c is further added to the IC tag shown in FIG. 1 and FIG. 2, the amplification effect is enhanced, while the frequency is lowered when the IC tag according to the third embodiment is assembled. May be larger than the IC tag of FIGS. For this reason, it is preferable that the resonance frequency of each of the IC tag circuit 1d, the first resonance circuit 1b, and the second resonance circuit 1c is set higher than those in FIGS. In this case, the number of turns of the first antenna 2a, the second antenna 2b, and the third antenna 2c is about 2 to 4, and the first capacitor 4b connected to the second antenna 2b and the third antenna 2c. The capacity of the third capacitor 4c is preferably matched to the capacity of the IC chip 3 connected to the first antenna 2a and the second capacitor 4a connected as necessary. For example, if the IC chip 3 has a capacitance of 30 pF and the second capacitor 4a has a capacitance of 220 pF, the first capacitor 4b has a capacitance of around 250 pF. When there is no capacitor near 250 pF, a plurality of capacitors may be connected in parallel so that the total capacitance is around 250 pF. Also in this case, it is preferable that the resonance frequency when the IC tag circuit 1d, the first resonance circuit 1b, and the second resonance circuit 1c are each single is set to the same value to some extent.

  According to the IC tag according to the third embodiment, the first antenna 2a wound around the magnetic core 6 is spaced from the second antenna 2b, the third antenna 2c,. By winding a plurality of coils around the magnetic core 6 with a gap, the amplification effect of the plurality of resonance circuits is further increased, the Q value is increased, and the communication distance can be further increased.

(Modification)
4 to 6 are modifications of the IC tag shown in FIGS. As shown in FIGS. 4A, 5A, and 6A, the IC chip 3, the first capacitor 4b, the second capacitor 4a, and the third capacitor 4c are mounted on the substrate 7, respectively. Has been. As shown in FIGS. 4B, 5B, and 6B, the substrate 7 is housed inside the core of the magnetic core 6 (in the hollow structure). By mounting the first capacitor 4b, the second capacitor 4a, and the third capacitor 4c on the substrate 7, it is possible to reduce mounting errors and misalignment of minute IC chips and capacitors during assembly. Workability at the time can be improved. Further, by storing the substrate 7 inside the magnetic core 6, further miniaturization can be achieved. At this time, a partial recess at the end of the magnetic core 6 may be provided so that the wiring connected to the substrate 7 does not protrude from the end face of the magnetic core 6.
1 to 6 and Examples 1 to 3 below show examples in which a cylindrical body obtained by rolling a single magnetic sheet into a cylindrical shape is used as the magnetic core 6. However, even when a laminated body in which a plurality of magnetic sheets are laminated as the magnetic core 6 is formed into a cylindrical body, substantially equivalent characteristics can be obtained.

  Examples and Comparative Examples of the present invention will be shown below, but these Examples are provided for better understanding of the present invention and its advantages, and the present invention includes the production order, production materials, etc. It is not intended to be limited to the description.

Example 1
As a material for the magnetic core 6, a magnetic sheet (RFN1) manufactured by Nitta Corporation was used. The thickness of the magnetic sheet is 300 μm, and the real part (μ ′) of the permeability is 50 in the 13.56 MHz band. One magnetic sheet was cut into a 12 mm × 170 mm strip, which was rounded into a cylindrical shape to produce a cylindrical magnetic core 6 having an outer diameter of 15 mm.

  Next, the first antenna 2 a and the second antenna 2 b were formed by winding them around the magnetic core 6. As the antenna material, a copper wire (USEW) manufactured by Riken Electric Wire Co., Ltd. was used. The diameter of the copper wire is 0.5 mm and the surface is insulated with a polyurethane resin. According to the outer diameter of the magnetic core 6, each was wound 9 turns with an inner diameter of 15 mm. At this time, the inductance of the first antenna 2a and the second antenna 2b was 1700 nH.

  Next, the first antenna 2a and the IC chip 3 were connected to produce an IC tag circuit 1a. As the IC chip 3, the IC chip 3 capable of communicating in the 13.56 MHz band was used. The IC chip 3 was mounted on a separately prepared substrate 7 by wire bonding, and the substrate 7 and the first antenna 2a were connected by solder. The resonance frequency of the single IC tag circuit 1a composed of the first antenna 2a and the IC chip 3 was 24.07 MHz.

  Next, the 2nd antenna 2b and the 1st capacitor | condenser 4b were connected, and the 1st resonance circuit 1b was produced. As the first capacitor 4b, a ceramic capacitor manufactured by Murata Manufacturing Co., Ltd. was used. A capacity of 33 pF was used. The first capacitor 4b was mounted on a separately prepared substrate 7 by soldering, and the substrate 7 and the second antenna 2b were connected by soldering. The resonance frequency of the single first resonance circuit 1b composed of the second antenna 2b and the first capacitor 4b was 22.18 MHz.

  Next, the distance between the first antenna 2a and the second antenna 2b wound around the magnetic core 6 was adjusted, and the target resonance frequency was set to 13.56 MHz. The distance between the first antenna 2a and the second antenna 2b was adjusted while measuring the target resonance frequency with a network analyzer. At this time, the interval between the first antenna 2a and the second antenna 2b was set to 2 mm.

  Next, the communication distance of the obtained IC tag was measured. The IC tag was placed on a height gauge, the distance between the reader / writer and the IC tag was reduced, and the longest distance that could be communicated was measured. The reader / writer used was an ISO14443 Type B communication protocol compatible product.

(Example 2)
First, as a material for the magnetic core 6, a magnetic sheet (RFN1) manufactured by Nitta Corporation was used. The thickness of the magnetic sheet is 300 μm, and the real part (μ ′) of the permeability is 50 in the 13.56 MHz band. The magnetic sheet was cut into 12 mm × 170 mm strips, which were rounded into a cylindrical shape to produce a circular cylindrical magnetic core 6 with an outer diameter of 15 mm.

  Next, the first antenna 2 a and the second antenna 2 b were wound around the magnetic core 6. As the antenna material, a copper wire (USEW) manufactured by Riken Electric Wire Co., Ltd. was used. The diameter of the copper wire is 0.5 mm and the surface is insulated with a polyurethane resin. In accordance with the outer diameter of the magnetic core 6, it was wound for two turns with an inner diameter of 15 mm. At this time, the inductance of the first antenna 2a and the second antenna 2b was 254 nH.

  Next, the first antenna 2a and the IC chip 3 were connected to produce an IC tag circuit 1d. As the IC chip 3, the IC chip 3 capable of communicating in the 13.56 MHz band was used. The IC chip 3 was mounted on a separately prepared substrate 7 by wire bonding, and the substrate 7 and the first antenna 2a were connected by solder. A second capacitor 4a was separately mounted on the substrate 7 by soldering. A ceramic capacitor manufactured by Murata Manufacturing Co., Ltd. was used as the second capacitor 4a. A capacity of 330 pF was used. The resonance frequency of the single IC tag circuit 1d composed of the first antenna 2a, the IC chip 3, and the second capacitor 4a was 22.86 MHz.

  Next, the 2nd antenna 2b and the 1st capacitor | condenser 4b were connected, and the 1st resonance circuit 1b was produced. As the first capacitor 4b, a ceramic capacitor manufactured by Murata Manufacturing Co., Ltd. was used. Capacitances of 330 pF and 33 pF were used (capacity was desired to be near 360 pF, but there was no capacitor near 360 pF, so two capacitors of 330 pF and 33 pF were connected in parallel and substituted). The first capacitor 4b was mounted on a separately prepared substrate 7 by soldering, and the substrate 7 and the second antenna 2b were connected by soldering. The resonance frequency of the first resonance circuit 1b alone composed of the second antenna 2b and the first capacitor 4b was 22.65 MHz.

  Next, the distance between the first antenna 2a and the second antenna 2b wound around the magnetic core 6 was adjusted, and the target resonance frequency was set to 13.56 MHz. The distance between the first antenna 2a and the second antenna 2b was adjusted while measuring the resonance frequency with a network analyzer. The distance between the first antenna 2a and the second antenna 2b at this time was set to 4.5 mm.

  Next, the communication distance of the obtained IC tag was measured. The IC tag was placed on a height gauge, the distance between the reader / writer and the IC tag was reduced, and the longest distance that could be communicated was measured. The reader / writer used was an ISO14443 Type B communication protocol compatible product.

(Example 3)
First, as a material for the magnetic core 6, a magnetic sheet (RFN1) manufactured by Nitta Corporation was used. The thickness of the magnetic sheet is 300 μm, and the real part (μ ′) of the permeability is 50 in the 13.56 MHz band. The magnetic sheet was cut into 12 mm × 170 mm strips, which were rounded into a cylindrical shape to produce a circular cylindrical magnetic core 6 with an outer diameter of 15 mm.

  Next, the first antenna 2 a, the second antenna 2 b, and the third antenna 2 c were wound around the outer periphery of the magnetic core 6. As a material, a copper wire (USEW) manufactured by Riken Electric Wire Co., Ltd. was used. The diameter of the copper wire is 0.5 mm and the surface is insulated with a polyurethane resin. In accordance with the outer diameter of the magnetic core 6, it was wound for two turns with an inner diameter of 15 mm. At this time, the inductances of the first antenna 2a, the second antenna 2b, and the third antenna 2c were 254 nH.

  Next, the first antenna 2a and the IC chip 3 were connected to produce an IC tag circuit 1d. As the IC chip 3, the IC chip 3 capable of communicating in the 13.56 MHz band was used. The IC chip 3 was mounted on a separately prepared substrate 7 by wire bonding, and the substrate 7 and the first antenna 2a were connected by solder. A second capacitor 4a was separately mounted on the substrate 7 with solder. A ceramic capacitor manufactured by Murata Manufacturing Co., Ltd. was used as the second capacitor 4a. A capacity of 220 pF was used. The resonance frequency of the single IC tag circuit 1d composed of the first antenna 2a, the IC chip 3, and the second capacitor 4a was 27.65 MHz.

  Next, the second antenna 2b and the first capacitor 4b are connected to connect the first resonance circuit 1b, and the third antenna 2c and the third capacitor 4c are connected to connect the second resonance circuit 1c. Each was produced. Ceramic capacitors manufactured by Murata Manufacturing Co., Ltd. were used for the first capacitor 4b and the third capacitor 4c. Capacitances of 220 pF and 22 pF were used, respectively (I wanted to make the capacity around 250 pF, but there was no capacitor near 250 pF, so two capacitors of 220 pF and 22 pF were connected in parallel). The first capacitor 4b and the third capacitor 4c were each mounted on a separately prepared substrate 7 by soldering, and the second antenna 2b and the third antenna 2c were respectively connected to the substrate 7 by soldering. The resonance frequencies of the second resonance circuit 1c including the second antenna 2b and the first capacitor 4b, and the second resonance circuit 1c including the third antenna 2c and the third capacitor 4c are 27. It was 55 MHz.

  Next, the distance between the first antenna 2a, the second antenna 2b, and the third antenna 2c wound around the magnetic core 6 was adjusted to set the target resonance frequency to 13.56 MHz. The resonance frequency was measured with a network analyzer, and the distance between the first antenna 2a, the second antenna 2b, and the third antenna 2c was adjusted. At this time, the interval between the first antenna 2a, the second antenna 2b, and the third antenna 2c was set to 2.0 mm.

  Next, the communication distance of the obtained IC tag was measured. The IC tag was placed on a height gauge, the distance between the reader / writer and the IC tag was reduced, and the longest distance that could be communicated was measured. The reader / writer used was an ISO14443 Type B communication protocol compatible product.

(Comparative Example 1)
As a comparative example, a conventional IC tag circuit in which an IC chip 3 is simply connected to an antenna was created. First, the antenna was wound in a circle. As a material, a copper wire (USEW) manufactured by Riken Electric Wire Co., Ltd. was used. The diameter of the copper wire is 0.5 mm and the surface is insulated with a polyurethane resin. It was wound for 16 turns with an inner diameter of 15 mm. At this time, the inductance of the antenna was 4735 nH.

  Next, an IC chip was connected to the antenna. As the IC chip, an IC chip capable of communicating in the 13.56 MHz band was used. The IC chip was mounted on a separately prepared substrate by wire bonding, and the substrate and the antenna were connected by solder. The resonance frequency of the IC tag circuit of Comparative Example 1 including an antenna and an IC chip was set to 13.56 MHz.

  Next, the communication distance of the obtained IC tag was measured. The IC tag was placed on a height gauge, the distance between the reader / writer and the IC tag was reduced, and the longest distance that could be communicated was measured. The reader / writer used was an ISO14443 Type B communication protocol compatible product.

(Comparative Example 2)
As Comparative Example 2, an example in which a capacitor was further mounted on the IC tag of Comparative Example 1, that is, a conventional IC tag circuit including an antenna, an IC chip 3, and a capacitor for adjusting resonance frequency was produced. First, the antenna was wound in a circle. As a material, a copper wire (USEW) manufactured by Riken Electric Wire Co., Ltd. was used. The diameter of the copper wire is 0.5 mm and the surface is insulated with a polyurethane resin. It was wound for 3 turns with an inner diameter of 15 mm. At this time, the inductance of the antenna was 382 nH.

  Next, the antenna and the IC chip were connected. As the IC chip, an IC chip capable of communicating in the 13.56 MHz band was used. The IC chip was mounted on a separately prepared substrate by wire bonding, and the substrate and the antenna were connected by solder. Separately, a capacitor was mounted on the substrate with solder. The capacitor used was a ceramic capacitor manufactured by Murata Manufacturing Co., Ltd. Capacitances of 390 pF and 120 pF were used. The resonance frequency of the IC tag circuit of Comparative Example 2 including an antenna, an IC chip, and a capacitor was set to 13.56 MHz.

  Next, the communication distance of the obtained IC tag was measured. The IC tag was placed on a height gauge, the distance between the reader / writer and the IC tag was reduced, and the longest distance that could be communicated was measured. The reader / writer used was an ISO14443 Type B communication protocol compatible product.

(Comparative Example 3)
As Comparative Example 3, an example in which a magnetic core is arranged on the IC tag of Comparative Example 2, that is, a conventional IC tag circuit including an antenna, an IC chip, and a capacitor for adjusting a resonance frequency and an IC tag including a magnetic core did.

  As a material for the magnetic core 6, a magnetic sheet (RFN1) manufactured by Nitta Corporation was used. The thickness of the magnetic sheet is 300 μm, and the real part (μ ′) of the permeability is 50 in the 13.56 MHz band. The magnetic sheet was cut into 12 mm × 170 mm strips and wound into a cylindrical shape to form a circular cylindrical magnetic core having an outer diameter of 15 mm.

  Next, the antenna was formed by winding it around a magnetic core. As a material, a copper wire (USEW) manufactured by Riken Electric Wire Co., Ltd. was used. The diameter of the copper wire is 0.5 mm and the surface is insulated with a polyurethane resin. According to the outer diameter of the magnetic core, it was wound for 2 turns with an inner diameter of 15 mm. At this time, the inductance of the antenna was 254 nH.

  Next, the antenna and the IC chip were connected. As the IC chip, an IC chip capable of communicating in the 13.56 MHz band was used. The IC chip was mounted on a separately prepared substrate by wire bonding, and the substrate and the antenna were connected by solder. Separately, a capacitor was mounted on the substrate with solder. The capacitor used was a ceramic capacitor manufactured by Murata Manufacturing Co., Ltd. Capacitances of 390 pF and 51 pF were used. The resonant frequency of the IC tag circuit composed of an antenna, an IC chip and a capacitor, and the IC tag composed of a magnetic core was set to 13.56 MHz.

  Next, the communication distance of the obtained IC tag was measured. The IC tag was placed on a height gauge, the distance between the reader / writer and the IC tag was reduced, and the longest distance that could be communicated was measured. The reader / writer used was an ISO14443 Type B communication protocol compatible product.

<Result>
Table 3 shows communication distances of the IC tags of Examples 1 to 3 and Comparative Examples 1 to 3.

  It can be seen that the communication distance is longer in each of Examples 1 to 3 than the IC tag having the configuration of Comparative Examples 1 to 3. In particular, in Example 2 in which the second capacitor 4a is added to the IC tag circuit and Example 3 in which the second resonance circuit 1c including the third antenna 2c and the third capacitor 4c is added, Comparative Examples 1 and 2 are used. It can be seen that the communication distance has increased to about twice that of the IC tag.

DESCRIPTION OF SYMBOLS 1a, 1d ... IC tag circuit 1b ... 1st resonance circuit 1c ... 2nd resonance circuit 2a ... 1st antenna 2b ... 2nd antenna 2c ... 3rd antenna 3 ... IC chip 4a ... 2nd capacitor | condenser 4b ... first capacitor 4c ... third capacitor 6 ... magnetic core 7 ... substrate

Claims (8)

A magnetic core;
An IC tag circuit including a first antenna wound around an outer periphery of the magnetic core and an IC chip connected to the first antenna;
A first resonant circuit including a second antenna spaced apart from the first antenna and wound around an outer periphery of the magnetic core, and a first capacitor connected to the second antenna. Characteristic IC tag.   The IC tag according to claim 1, wherein the IC tag circuit further includes a second capacitor connected to the first antenna.   The IC tag according to claim 1 or 2, wherein a difference between a resonance frequency of the single IC tag circuit and a resonance frequency of the single first resonance circuit is within 2 MHz. The magnetic core has a hollow structure;
The IC tag according to claim 1, wherein the IC chip and the first capacitor are accommodated in the hollow structure.   The IC tag according to any one of claims 1 to 4, wherein the magnetic core includes a cylinder formed by rounding one magnetic sheet.   The IC tag according to claim 1, wherein the first antenna and the second antenna are separated by 2 to 5 mm.   The IC tag according to any one of claims 2 to 6, wherein the number of turns of the first antenna and the second antenna is 2 to 4 turns.   A second resonance circuit including a third antenna spaced apart from the first and second antennas and wound around an outer periphery of the magnetic core and a third capacitor connected to the third antenna; The IC tag according to claim 1, further comprising:

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