WO2017038885A1 - Antenne magnétique et dispositif d'antenne - Google Patents

Antenne magnétique et dispositif d'antenne Download PDF

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Publication number
WO2017038885A1
WO2017038885A1 PCT/JP2016/075537 JP2016075537W WO2017038885A1 WO 2017038885 A1 WO2017038885 A1 WO 2017038885A1 JP 2016075537 W JP2016075537 W JP 2016075537W WO 2017038885 A1 WO2017038885 A1 WO 2017038885A1
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WIPO (PCT)
Prior art keywords
coil conductor
magnetic
magnetic core
coil
antenna
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Application number
PCT/JP2016/075537
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English (en)
Japanese (ja)
Inventor
敬介 國森
加奈 原本
木村　哲也
山本　一美
由郎 佐藤
Original Assignee
戸田工業株式会社
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Priority to JP2017538079A priority Critical patent/JPWO2017038885A1/ja
Publication of WO2017038885A1 publication Critical patent/WO2017038885A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/34—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F17/00—Fixed inductances of the signal type 
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q7/00—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
    • H01Q7/06—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop with core of ferromagnetic material
    • H01Q7/08—Ferrite rod or like elongated core

Definitions

  • the present disclosure relates to a magnetic antenna and an antenna device.
  • An antenna device that uses a magnetic antenna is known as an antenna device that performs wireless communication.
  • a magnetic antenna performs communication by magnetic coupling and usually includes a magnetic core and a coil conductor.
  • Patent Document 1 proposes that an antenna device is downsized and used for a communication terminal device used in NFC (Near Field Communication), Felica, and the like, a small radio, and the like. Patent Document 1 proposes that at least a part of the second coil conductor formed so as to be wound in the same direction as the first coil conductor is formed inside the magnetic core.
  • NFC Near Field Communication
  • Patent Document 1 proposes that at least a part of the second coil conductor formed so as to be wound in the same direction as the first coil conductor is formed inside the magnetic core.
  • Patent Document 2 proposes a device system in which an antenna is integrated into a separate module such as SIM or ⁇ SD, and directly communicates with an external coil.
  • the separation type module has a terminal function that is not restricted by a portable terminal or the like, and a server access function via a network. This makes it possible to separate and replace a module that stores unique information related to an access method and security as a heart from a portable terminal having a simple communication function.
  • Various wireless communication technologies are used as data carriers.
  • adjacent coil conductors communicate with each other by magnetic coupling.
  • the magnetic coupling strength between the two coil conductors is represented by a mutual inductance M.
  • the mutual inductance M can be obtained by the following equation.
  • LA and LB indicate the inductances of the coil conductors close to each other.
  • K represents a coupling coefficient (0 ⁇ k ⁇ 1).
  • R resistance
  • Q quality factor
  • the magnetic antenna when the magnetic antenna is integrated with a separate storage module such as a micro SIM and a micro SD, it is necessary to reduce the size of the magnetic antenna.
  • the coil conductor when the coil conductor is reduced in size, the mutual inductance M is reduced.
  • the number of turns of the coil conductor is increased, the size of the magnetic antenna increases, making it difficult to meet the demand for downsizing. Therefore, there is a need for a magnetic antenna that can satisfy both miniaturization and communication distance at a sufficiently high level, and an antenna device including the same.
  • An object of the present invention in one aspect, is to provide a magnetic antenna that can increase the communication distance while enabling downsizing. In another aspect, an object of the present invention is to provide an antenna device capable of increasing the communication distance while enabling downsizing.
  • the present invention includes a magnetic core having a rectangular parallelepiped shape, and a first coil conductor and a second coil conductor that are alternately wound around the magnetic core, and the first coil conductor and the second coil conductor. Provides a magnetic antenna connected in parallel.
  • the first coil conductor and the second coil conductor are connected in parallel.
  • the resistance and inductance of the first coil conductor and the second coil conductor are the same, and when the resistance is R 0 and the inductance is L 0 , when the first coil conductor and the second coil conductor are connected in parallel,
  • the combined resistance and combined inductance are typically R 0/2 and L 0/2 .
  • the first coil conductor and the second coil conductor are alternately wound around each other, so that the magnetic mutual induction action Mc between the first coil conductor and the second coil conductor. makes the actual combined inductance is larger than L 0/2.
  • the combined inductance L can be increased while reducing the resistance by parallel connection. Therefore, it is possible to increase the communication distance by increasing the M ⁇ Q product.
  • the first coil conductor and the second coil conductor are wound around the magnetic core so that the winding axes of the first coil conductor and the second coil conductor are orthogonal to the longitudinal direction of the rectangular parallelepiped magnetic core. Also good. For this reason, compared with the case where the winding axis of a 1st coil conductor and a 2nd coil conductor is parallel to the longitudinal direction of a magnetic core, the cross-sectional area of the loop of a 1st coil conductor and a 2nd coil conductor can be enlarged.
  • the mutual inductance M can be increased by increasing the combined inductance L and the coupling coefficient k of the first coil conductor and the second coil conductor. it can. Accordingly, the magnetic coupling strength can be further increased and the communication distance can be further increased.
  • the inductances of the first coil conductor and the second coil conductor are L 1 and L 2
  • the combined inductance of the first coil conductor and the second coil conductor is L
  • the first coil conductor and the second coil When the resistance of the conductor is R L1 and R L2 , and the combined resistance of the first coil conductor and the second coil conductor is R, the following expressions (1) and (2) may be satisfied.
  • a conductor layer is provided on at least one surface of the magnetic core via an insulating layer, and the first coil conductor and the second coil conductor may be sandwiched between the magnetic core and the insulating layer. Good. Accordingly, a sufficiently long communication distance can be ensured even when the conductive member is mounted in an electronic device and is close to the conductive member.
  • the present invention includes a magnetic core having a rectangular parallelepiped shape, and a plurality of coil conductors wound side by side on the magnetic core, and the plurality of coil conductors are connected in parallel.
  • a body antenna Provides a body antenna.
  • a plurality of coil conductors are connected in parallel.
  • the resistance and inductance of the plurality (n) of coil conductors are the same, and each resistance is R 0 and the inductance is L 0
  • n coil conductors are wound side by side, so that the actual combined inductance is L 0 // due to the magnetic mutual induction between adjacent coil conductors. It becomes larger than n.
  • the magnetic antenna can increase the M ⁇ Q product while reducing the resistance by parallel connection. As a result, the communication distance can be increased.
  • a plurality of coil conductors may be wound around the magnetic core so that winding axes of the plurality of coil conductors are orthogonal to the longitudinal direction of the rectangular parallelepiped magnetic core. For this reason, compared with the case where the winding axis of a some coil conductor is parallel to the longitudinal direction of a magnetic core, the cross-sectional area of the loop of a some coil conductor can be enlarged. Therefore, even if the number of turns of the plurality of coil conductors is reduced in order to reduce the size of the magnetic antenna, the combined inductance L and the coupling coefficient k of the plurality of coil conductors can be increased and the mutual inductance M can be increased.
  • the plurality of coil conductors is composed of n coil conductors, where n is an integer greater than or equal to 2, each inductance of the plurality of coil conductors is L n , and the combined inductance of the plurality of coil conductors is L
  • n is an integer greater than or equal to 2
  • each inductance of the plurality of coil conductors is L n
  • the combined inductance of the plurality of coil conductors is L
  • the magnetic antenna includes a conductor layer on at least one surface of a magnetic core via an insulating layer, and the plurality of coil conductors may be sandwiched between the magnetic core and the insulating layer. Accordingly, a sufficiently long communication distance can be ensured even when the conductive member is mounted in an electronic device and is close to the conductive member.
  • the magnetic core may be composed of a Ni—Zn—Cu ferrite sintered body having a real part of magnetic permeability at 13.56 MHz of 20 to 90 and an imaginary part of 0.2 to 2. Good.
  • the resistance component can be reduced by sufficiently reducing the imaginary part ( ⁇ ′′) of the magnetic permeability. Therefore, the quality factor Q can be increased. Therefore, the magnetic antenna can be further reduced in size.
  • the magnetic core is composed of ferrite containing Co as a constituent element, and Ni—Zn—Cu based ferrite sintered body containing 0.05 to 1.0 mass% of Co in terms of CoO. It may be comprised.
  • the Ni—Zn—Cu ferrite sintered body is composed of ferrite containing Fe, Ni, Zn, Cu, Co, and O as constituent elements, and Fe, Ni, Zn, and Cu are respectively converted into Fe 2 O 3 , When converted to NiO, ZnO and CuO, based on the total of Fe 2 O 3 , NiO, ZnO and CuO, Fe 2 O 3 is 46 to 50 mol%, NiO is 20 to 27 mol%, and ZnO is 15 to 22 mol%. , And 9 to 11 mol% of CuO. As a result, the magnetic loss can be further reduced and the quality factor Q can be increased, so that the communication distance of the magnetic antenna can be further increased.
  • the magnetic antenna has a ratio (L b / L a ) of the length L b of the magnetic core in the axial direction of the winding axis to the length L a of the magnetic core in the longitudinal direction. It may be ⁇ 0.6.
  • the present invention provides an antenna device including the above-described magnetic antenna and an electronic component electrically connected to the magnetic antenna. Since this antenna device includes the magnetic antenna, the antenna device can be miniaturized and the communication distance can be sufficiently increased.
  • the present invention can provide a magnetic antenna capable of reducing the size and increasing the communication distance. In another aspect, the present invention can provide an antenna device capable of extending the communication distance while enabling downsizing.
  • FIG. 1 is a perspective view showing a magnetic antenna according to an embodiment.
  • FIG. 2 is a circuit diagram of the first coil conductor and the second coil conductor in the magnetic antenna of FIG. 3 is a cross-sectional view taken along the line III-III of the magnetic antenna of FIG.
  • FIG. 4 is a diagram schematically showing the internal structure of the storage module.
  • FIG. 5 is a block diagram of the storage module 100.
  • FIG. 6 is a diagram for explaining a communication method of the antenna device.
  • FIG. 7 is a circuit diagram of the magnetic antenna and the reader / writer.
  • FIG. 8 is an equivalent circuit model when the magnetic antenna and the reader / writer are magnetically coupled.
  • FIG. 9 is an exploded perspective view showing a laminated state of the ferrite molded sheet.
  • FIG. 10 is a perspective view showing a magnetic antenna according to another embodiment.
  • FIG. 11 is a diagram showing a magnetic antenna of Comparative Example 1.
  • FIG. 12 is a circuit diagram of a coil conductor in
  • FIG. 1 is a perspective view of a magnetic antenna 10 according to an embodiment.
  • the magnetic antenna 10 includes a magnetic core 12 having a rectangular parallelepiped shape, and a first coil conductor 14 and a second coil conductor 15 that are wound around the magnetic core 12 in parallel.
  • the magnetic antenna 10 also has a substantially rectangular parallelepiped shape.
  • the first coil conductor 14 and the second coil conductor 15 are wound around the winding axis P in line with each other.
  • the first coil conductor 14 and the second coil conductor 15 are wound in parallel along the surface of the magnetic core 12 and have the same winding axis P.
  • the first coil conductor 14 and the second coil conductor 15 are joined to form a parallel circuit at each end portion to form terminals 16a and 16b.
  • the terminals 16a and 16b can be connected to an external circuit.
  • the first coil conductor 14 and the second coil conductor 15 function as an antenna.
  • the number of turns of the first coil conductor 14 and the second coil conductor 15 is three, but is not limited thereto.
  • the coupling coefficient k may be increased by increasing the number of turns of the first coil conductor 14 and the second coil conductor 15.
  • the number of turns of the first coil conductor 14 and the second coil conductor 15 may be the same or different. By making the number of windings the same, processing can be facilitated.
  • the first coil conductor 14 and the second coil conductor 15 are wound around the magnetic core 12 so that the winding axis P is orthogonal to the longitudinal direction of the magnetic core 12. Thereby, the cross-sectional area of the loop of the first coil conductor 14 and the second coil conductor 15 can be increased, and the inductance and the coupling coefficient k can be increased.
  • the material of the first coil conductor 14 and the second coil conductor 15 include copper, silver, or an alloy containing at least one of these.
  • first coil conductor 14 and the second coil conductor 15 and the magnetic core 12 are in close contact with each other.
  • the magnetic antenna 10 can be further reduced in size, and the combined inductance of the first coil conductor 14 and the second coil conductor 15 can suppress a decrease in the combined inductance. Further, it can be easily mounted inside a storage module or the like.
  • the first coil conductor 14 and the second coil conductor 15 are provided separately so as to form a parallel circuit.
  • FIG. 2 is a circuit diagram of the first coil conductor 14 and the second coil conductor 15 in the magnetic antenna 10.
  • Mc indicates the mutual inductance of the first coil conductor 14 and the second coil conductor 15.
  • the inductance of the first coil conductor 14 is L 1 and the inductance of the second coil conductor 15 is L 2
  • the combined inductance L of the first coil conductor 14 and the second coil conductor 15 satisfies the following formula (1).
  • the combined inductance L of the first coil conductor 14 and the second coil conductor 15 of the magnetic antenna 10 is larger than the value calculated from This is due to the magnetic mutual induction action between the first coil conductor 14 and the second coil conductor 15.
  • the combined resistance R of the first coil conductor 14 and the second coil conductor 15 connected in parallel is expressed by the calculated value of the above formula (2), whereas the combined inductance L is usually as shown by the above formula (1). It becomes larger than the calculated value.
  • the mutual inductance M between the magnetic antenna 10 during communication and the antenna of the communication partner increases, and the magnetic coupling strength can be increased. As a result, the communication distance can be increased.
  • FIG. 3 is a cross-sectional view of the magnetic antenna 10 of FIG. 1 taken along the line III-III.
  • the cross-sectional areas of the loops of the first coil conductor 14 and the second coil conductor 15 in this specification are the cross-sectional areas of the loops when viewed in a cross section as shown in FIG. That is, the cross-sectional area of the loop of the coil conductor in this specification is an area inside the loop formed of the coil conductor when viewed from the axial direction of the winding axis P.
  • the cross-sectional area of the loop of the first coil conductor 14 and the cross-sectional area of the loop of the second coil conductor 15 are the same. Thereby, the manufacturing process of the magnetic antenna 10 can be facilitated.
  • the first coil conductor 14 and the second coil conductor 15 are provided on the surface of the magnetic core 12 which is a magnetic body. Therefore, the cross-sectional areas of the loops of the first coil conductor 14 and the second coil conductor 15 can be increased as compared with the case where the loop is embedded in the magnetic body. Further, the radiation magnetic field is suppressed from being taken into the magnetic body, and the communication distance can be increased.
  • the first coil conductor 14 and the second coil conductor 15 (a plurality of coil conductors) are parallel to each other and have the same number of turns. Thereby, the manufacturing process of the magnetic antenna 10 can be facilitated.
  • the ratio of the length L b of the magnetic core 12 in the axial direction of the winding axis P (L b / L a), for example 0.2-0.6 It may be 0.2 to 0.5.
  • the number of turns of the first coil conductor 14 and the second coil conductor 15 while increasing the cross-sectional area of the first coil conductor 14 and the second coil conductor 15 by setting the ratio (L b / L a ) in the above range. can be more. As a result, the communication distance can be further increased while further reducing the size of the magnetic antenna 10.
  • the ratio of the vertical length L a to the thickness L c (L a / L c ) may be, for example, 5 to 50, 10 May be 40.
  • the size of the magnetic core 12 is, for example, a vertical length L a : 5 to 15 mm, a horizontal length L b : 3 to 5 mm, and a thickness L c : 0.3 to 0.5 mm. By adopting such a size, it can be sufficiently mounted on a micro SD card or a SIM card.
  • the magnetic antenna 10 has a similar size.
  • the magnetic core 12 is formed by firing a laminate in which a plurality of molded sheets are laminated.
  • the molded sheet is, for example, a ferrite molded sheet.
  • the magnetic core 12 may be composed of a laminated body of a plurality of magnetic layers 12a, 12b, and 12c, or a plurality of molded sheets are integrated by firing to form a single magnetic layer. It may be. Further, it may be formed by firing one molded sheet.
  • the magnetic core 12 is made of, for example, a sintered body.
  • the composition of the sintered body is not particularly limited, and for example, it may be composed of Ni—Zn—Cu based ferrite having Fe, Ni, Zn, Cu, Co and O as constituent elements.
  • Examples of the oxide used as a raw material for obtaining a Ni—Zn—Cu ferrite sintered body include Fe 2 O 3 , NiO, ZnO, CuO, and CoO.
  • the Ni—Zn—Cu-based ferrite sintered body is composed of ferrite containing Co as a constituent element, and Co may be contained in an amount of 0.05 to 1.0% by mass in terms of CoO. It may be contained in an amount of 1 to 0.5% by mass.
  • CoO in such a range, magnetic loss at a communication frequency of 13.56 MHz can be sufficiently reduced. Therefore, it can be particularly suitably used as a magnetic antenna for NFC communication.
  • the Ni—Zn—Cu ferrite sintered body is composed of ferrite having Fe, Ni, Zn, Cu, Co and O as constituent elements.
  • the Ni—Zn—Cu ferrite sintered body is the sum of Fe 2 O 3 , NiO, ZnO and CuO when Fe, Ni, Zn and Cu are converted into Fe 2 O 3 , NiO, ZnO and CuO, respectively. From the above, Fe 2 O 3 is contained in an amount of 46 to 50 mol%, NiO in an amount of 20 to 27 mol%, ZnO in an amount of 15 to 22 mol%, and CuO in an amount of 9 to 11 mol%.
  • the content of Fe 2 O 3 may be 47 to 49 mol% with respect to the total.
  • the content of NiO may be 24 to 26 mol% with respect to the total.
  • the ZnO content may be 15.5 to 16.5 mol% with respect to the total.
  • the CuO content may be 9.4 to 11 mol% with respect to the total.
  • the content of each component can be obtained by converting the content of each metal element obtained by fluorescent X-ray analysis or ICP emission spectroscopic analysis into an oxide.
  • the Ni—Zn—Cu ferrite sintered body having the above-described composition has a sufficiently small imaginary part ( ⁇ ′′) of the magnetic permeability.
  • the magnetic core 12 of the magnetic antenna 10 has a real part ( ⁇ ′) of the magnetic permeability. Since the imaginary part ( ⁇ ′′) of the magnetic permeability is sufficiently reduced while being kept high, the communication distance can be made sufficiently long.
  • the compositions of the magnetic layers 12a, 12b, and 12c may be the same or different.
  • the imaginary part ( ⁇ ′′) of the magnetic permeability of the Ni—Zn—Cu ferrite sintered body may be, for example, 0.1 to 2, or may be 0.1 to 1.
  • the part ( ⁇ ′) may be, for example, 20 to 90 or 30 to 80.
  • the magnetic permeability in this specification is a flat plate ring sample having an outer diameter of 20 mm, an inner diameter of 10 mm, and a thickness of 1 mm. Is a value measured at a frequency of 13.56 MHz by a commercially available impedance / material analyzer.
  • FIG. 4 is a diagram schematically showing the internal structure of the storage module 100.
  • Examples of the storage module 100 include micro SD, SIM, USB, and the like.
  • An antenna device 60 is built in the housing 50 of the storage module 100.
  • the antenna device 60 includes the printed wiring board 40 and the magnetic antenna 10 and the electronic component 30 on the main surface of the printed wiring board 40.
  • the electronic component 30 is, for example, an IC chip.
  • the electronic component 30 is not limited to an IC chip, and may be a capacitor or a matching circuit, for example.
  • the antenna device 60 may include a plurality of electronic components 30.
  • FIG. 5 is a block diagram of the storage module 100.
  • the magnetic antenna 10 terminal 16a and 16b in FIG. 1 and the electronic component 30 are electrically connected by wiring (not shown) on the printed wiring board 40.
  • the printed wiring board 40 is electrically connected to an interface unit 82 built in the storage module 100.
  • the antenna device 60 resonates at a frequency of 13.56 MHz, for example, and has a function of communicating with a reader / writer or the like. Since the antenna device 60 including the magnetic antenna 10 is small and has a sufficiently long communication distance, it can be suitably mounted on the storage module 100.
  • the storage module 100 includes a control unit 80, a storage unit 84, an interface unit 82, and the like in addition to the antenna device 60.
  • the control unit 80 may have a function of processing a signal transmitted from the electronic component 30 via the interface unit 82 and writing data obtained from the signal to the storage unit 84.
  • the control unit 80 may have a function of reading data from the storage unit 84 and transmitting a signal obtained by processing the data to the electronic component 30 via the interface unit 82.
  • the control unit 80 has a CPU, for example.
  • the storage unit 84 includes, for example, a ROM or a RAM. Note that the storage module 100 is not limited to the above-described configuration.
  • the storage module 100 has a communication function by including the magnetic antenna 10.
  • the storage module 100 has a terminal function that is not restricted by a portable terminal or the like and a server access function via a network.
  • the storage module 100 is attached to a mobile terminal and connected to the network using the mobile terminal. After that, the storage module 100 can be detached from the mobile terminal, the storage module 100 can be attached to another mobile terminal, and connected to the network using the other mobile terminal.
  • FIG. 6 is a diagram illustrating an example of wireless communication between the magnetic antenna 10 (antenna device 60) provided in the housing 50 of the storage module 100 and the reader / writer 200 that is a communication partner of the magnetic antenna 10.
  • the storage module 100 is built in the mobile terminal 150.
  • the reader / writer 200 includes a coiled antenna 210 wound so as to form a loop in the vertical direction of FIG.
  • the reader / writer 200 is provided with a substrate (not shown), an electronic circuit mounted on the substrate, a power source, and the like.
  • the antenna 210 is electrically connected to an electronic circuit and a power source.
  • the reader / writer 200 may be a mobile terminal such as a smartphone, for example.
  • magnetic lines of force that penetrate the loop of the antenna 210 from the bottom to the top are drawn by a one-dot chain line.
  • the magnetic antenna 10 is magnetically coupled to the reader / writer 200.
  • the magnetic flux changes.
  • the electromagnetic electromotive force E between the terminals 16a and 16b of the first coil conductor 14 and the second coil conductor 15 changes.
  • the electronic component 30 shown in FIGS. 4 and 5 operates, and data stored in the storage unit 84 of the storage module 100 can be read and written to the storage unit 84. In this way, the storage module 100 and the reader / writer 200 can communicate.
  • FIG. 7 is a circuit diagram of the antenna device 61 and the reader / writer 200.
  • FIG. 8 is an equivalent circuit model when the antenna device 61 and the reader / writer 200 are magnetically coupled.
  • the antenna device 61 includes the magnetic antenna 10 and a capacitor C2 as an electronic component.
  • LA indicates the inductance of the antenna 210 of the reader / writer 200
  • LB indicates the inductance of the magnetic antenna 10 of the antenna device 61.
  • R1 represents the winding resistance of the antenna 210
  • R2 represents the sum of the winding resistance of the magnetic antenna 10 and the imaginary part ( ⁇ ′′) of the magnetic permeability.
  • Rg represents the output resistance
  • RI represents the load resistance. Respectively.
  • the magnetic coupling strength between the magnetic antenna 10 and the antenna 210 is a mutual inductance M (FIG. 8).
  • the mutual inductance M is expressed by the following formula.
  • k represents a coupling coefficient (0 ⁇ k ⁇ 1).
  • the coupling coefficient k depends on the cross-sectional area of the loop of the coil conductor (antenna) and the distance between the antennas.
  • the coil inductances LA and LB depend on the product of the number of turns of the coil conductor, the cross-sectional area of the coil conductor, and the permeability of the magnetic body (magnetic core 12). Even if the magnetic antenna 10 of this embodiment is reduced in size, the cross-sectional areas of the loops of the first coil conductor 14 and the second coil conductor 15 can be increased.
  • the Ni—Zn—Cu ferrite sintered body constituting the magnetic core 12 of the magnetic antenna 10 has the imaginary part reduced while maintaining the real part of the magnetic permeability.
  • a calcined powder of Ni—Zn—Cu ferrite having a predetermined composition is prepared.
  • This calcined powder contains a predetermined amount of cobalt oxide.
  • a slurry is prepared by blending a calcined powder with a solvent, a plasticizer, a resin component, and the like.
  • the slurry is, for example, 70 to 120 parts by mass of polyvinyl alcohol resin, 15 to 25 parts by mass of butyl butyl phthalate as a plasticizer, and 400 to 600 parts of solvent for 1000 parts by mass of calcined powder of Ni—Zn—Cu ferrite. It is prepared by blending at a ratio of parts by mass.
  • As the solvent glycol ether, MEK, toluene, methanol, ethanol, n-butanol and the like can be used.
  • the prepared slurry is applied to a resin film.
  • the coating method is not particularly limited, and a roll coater or a doctor blade can be used.
  • the slurry can be dried at 80 to 130 ° C. for 30 to 60 minutes to obtain a plate-like ferrite molded sheet.
  • conductive paste a metal-based conductive paste such as an Ag paste or an Ag-based alloy paste can be used.
  • a conductive paste is applied to the main surface of some ferrite molded sheets by a method such as printing or brushing. At this time, a conductive paste is applied so as to pass over the through-hole, and the through-hole is filled with the conductive paste.
  • the conductive pattern used as the 1st coil conductor 14 and the 2nd coil conductor 15 is formed, and it is set as a ferrite forming sheet.
  • FIG. 9 is an exploded perspective view showing a laminated state of the ferrite molded sheet.
  • the magnetic antenna 10 is manufactured by firing the laminated body 13 of the ferrite molded sheets 13a, 13b, and 13c having the predetermined conductive patterns 14 'and 15'.
  • the magnetic antenna 10 including the magnetic core 12 and the first coil conductor 14 and the second coil conductor 15 wound around the magnetic core 12 as shown in FIG. 1 is obtained.
  • the antenna device can be obtained by electrically connecting the magnetic antenna 10 and the electronic component 30.
  • the magnetic antenna 10 and the electronic component 30 may be electrically connected by being mounted on the printed wiring board 40, or the electronic component 30 may be provided on the magnetic core 12 of the magnetic antenna 10.
  • the terminals 16a and 16b and the electronic component 30 may be connected directly or via wiring.
  • the present invention is not limited to the above embodiments.
  • the winding axis P and the longitudinal direction of the magnetic core may be parallel.
  • the magnetic core 12 is not limited to a ferrite sintered body, and may be another magnetic body.
  • FIG. 10 is a perspective view showing a magnetic antenna 11 according to another embodiment. Similar to the magnetic antenna 10 shown in FIG. 1, the magnetic antenna 11 shown in FIG. 10 includes a magnetic core 12 and a first coil conductor 14 wound around the magnetic core 12. The magnetic antenna 11 is different from the magnetic antenna 10 in that a conductor layer 72 is provided on one surface of the magnetic core 12 via an insulating layer 71.
  • the insulating layer 71 has an adhesion function and includes, for example, a resin.
  • the conductor layer 72 includes, for example, a metal.
  • the insulating layer 71 and the conductor layer 72 may be provided only on one surface of the magnetic core 12 as shown in FIG. 10, or may be provided on the other surface opposite to the one surface after providing electronic components and the like. Good. That is, the insulating layer 71 and the conductor layer 72 may be provided so as to cover the entire one surface and the other surface of the magnetic core 12.
  • the first coil conductor 14 and the second coil conductor 15 are not necessarily connected on the surface of the magnetic core 12, and may be connected on the printed wiring board 40 and connected in parallel, for example.
  • the number of coil conductors wound around the magnetic core 12 is not limited to two, and three or more coil conductors may be wound around the magnetic core 12 in parallel. Even in such an embodiment, by increasing the mutual inductance M, the magnetic coupling strength at the time of communication can be increased and the communication distance can be increased.
  • n coil conductors (n is an integer of 2 or more, or an integer of 3 or more) are wound around the magnetic core 12 in order
  • the inductances of the n coil conductors are expressed as L n
  • the combined inductance of the plurality of coil conductors is L, it is preferable to satisfy the following formula (3).
  • the combined resistance R of the n coil conductors connected in parallel is expressed by the calculated value of the above equation (4), whereas the combined inductance L is larger than the normal calculated value as shown by the above equation (3).
  • the mutual inductance M between the magnetic antenna 10 during communication and the antenna of the communication partner increases, and the magnetic coupling strength can be increased.
  • the M ⁇ Q product can be increased and the communication distance can be increased.
  • the number of turns of each of the plurality of coil conductors is not necessarily the same, and may be different.
  • Example 1 [Production of magnetic antenna] Iron oxide, nickel oxide, zinc oxide, copper oxide and cobalt oxide were weighed. The blending ratio of each raw material was as follows. ⁇ Fe 2 O 3: 48.5mol% NiO: 25.1 mol% ZnO: 16 mol% CuO: 10.4 mol% ⁇ CoO: 0.3wt%
  • Fe 2 O 3 , NiO, ZnO, and CuO were blended in the above ratio.
  • the mass ratio of CoO was blended at the above mass ratio with respect to the total of Fe 2 O 3 , NiO, ZnO, CuO and CoO.
  • the raw materials obtained by blending were wet mixed using a ball mill for 20 hours. Thereafter, drying, calcination, and pulverization were sequentially performed to obtain a calcined ferrite powder. 80 parts by mass of a solvent, 8 parts by mass of a butyral resin, and 5 parts by mass of a plasticizer were blended with 100 parts by mass of the calcined ferrite powder, and wet mixing was performed using a ball mill for 20 hours.
  • the obtained mixed slurry was applied onto a PET film by a doctor blade method and dried to prepare a ferrite molded sheet. Through holes were formed in the ferrite molded sheet and filled with Ag paste. Moreover, Ag paste was printed on the main surface of the ferrite molded sheet to form a predetermined conductive pattern.
  • the ferrite molded sheet on which the conductive pattern was formed was cut along a straight line passing through the center of the through hole and divided into a plurality of ferrite molded sheets.
  • Four divided ferrite molded sheets were stacked and pressed, and the ferrite molded sheets adjacent in the stacking direction were brought into close contact with each other.
  • the laminated ferrite molded sheets were baked in the atmosphere at 900 ° C. for 2 hours to produce a magnetic antenna as shown in FIG.
  • the first coil conductor and the second coil conductor are formed in parallel.
  • the size of the magnetic core and the number of turns of each of the first coil conductor and the second coil conductor were as shown in Table 1.
  • the line width of the first coil conductor and the second coil conductor was 0.2 mm, and the interval (line interval) between the adjacent first coil conductor and second coil conductor was 0.2 mm.
  • the composition of the Ni—Zn—Cu ferrite sintered body constituting the magnetic core was the same as the blending ratio of the raw materials.
  • the above-mentioned ferrite molded sheet was separately produced in order to measure the magnetic permeability of the Ni—Zn—Cu ferrite sintered body provided as a magnetic core in the magnetic antenna.
  • Ten ferrite molded sheets were laminated to produce a ring-shaped laminate having a thickness of 1 mm, and fired under the same conditions as those for producing the magnetic core of the magnetic antenna.
  • the Ni—Zn—Cu ferrite sintered body thus obtained was used for measuring the magnetic permeability.
  • IC AMS, product name: AS3922, RF front end
  • AMS AMS, product name: AS3953, for digital processing
  • capacitor An antenna device having a resonance frequency adjusted to 13.56 MHz was manufactured.
  • the impedance characteristics of the antenna device were measured using the above-described impedance analyzer. The measurement results are shown in the “impedance after matching” column of Table 2. Further, the communication distance between the produced antenna device and a portable terminal (product name: Nexus-S Ver 4.0.4, manufactured by Google) was measured. The measurement results are shown in Table 2.
  • Example 2 Example 1 except that the number of turns of the first coil conductor and the second coil conductor and the line widths and line intervals of the first coil conductor and the second coil conductor were changed as shown in Table 1 according to the number of turns.
  • a magnetic antenna was prepared in the same manner as described above. Then, evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 2.
  • Example 3 Same as Example 1 except that the first coil conductor and the second coil conductor are formed so that the axial direction of the winding axis of the first coil conductor and the second coil conductor is parallel to the longitudinal direction of the magnetic core.
  • Table 1 shows the size of the magnetic core, the number of turns of the first coil conductor and the second coil conductor, and the line widths and line intervals of adjacent coil conductors. Then, evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 2.
  • Example 4 Impedance was adjusted by laminating an insulating layer and a metal conductor layer from the magnetic core side so as to cover the surface where the magnetic IC in the antenna device of Example 2 was disposed and the entire surface facing the surface.
  • a double-sided adhesive tape manufactured by Tesa Tape Co., Ltd., product number: 8851, thickness: 30 ⁇ m
  • a copper foil thickness: 20 ⁇ m
  • the winding axis of the first coil conductor and the second coil conductor is parallel to the longitudinal direction of the magnetic core, and as shown in FIG. 11, the first coil conductor 14 and the second coil conductor 15 are alternately arranged.
  • a magnetic antenna was manufactured in the same manner as in Example 1 except that the magnetic core 12 was provided separately on the left side and the right side of the magnetic core 12.
  • the magnetic antenna of Comparative Example 1 had a structure as shown in FIG. Terminals 14 a and 14 b are formed at both ends of the first coil conductor 14 and terminals 15 a and 15 b are formed at both ends of the second coil conductor 15, respectively, in the magnetic antenna of Comparative Example 1.
  • Table 1 shows the size of the magnetic core, the number of turns of the first coil conductor and the second coil conductor, and the line widths and line intervals of adjacent coil conductors. Then, evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 2.
  • Comparative Example 2 instead of the magnetic core of Example 1, paper having the same size as the magnetic core was prepared. A copper wire was wound around this paper to obtain an antenna of Comparative Example 2. However, the size and shape of these loops were the same as in Example 1. That is, the number of turns of the first coil conductor and the second coil conductor, and the line widths and line intervals of the first coil conductor and the second coil conductor were as shown in Table 1. The column of the magnetic core in Table 1 shows the paper size. Then, evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 2.
  • Example 3 A magnetic antenna was manufactured in the same manner as in Example 1 except that only one coil conductor was formed and that the number of turns of the coil conductor was 2. The size of the magnetic core, the line width of the coil conductor, and the line interval were as shown in Table 1. Then, evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 2.
  • the communication distance could be made sufficiently long. All the examples were equal to or greater than the lower limit (25 mm) of the communication distance defined by the NFC Forum. This is because the decrease in inductance is suppressed and the resistance is reduced by half due to the increased cross-sectional area of the first coil conductor and the second coil conductor and the magnetic mutual induction action between the first coil conductor and the second coil conductor. This is probably due to the fact that
  • FIG. 12 is a circuit diagram of a coil conductor in the magnetic antenna of Comparative Example 1.
  • Comparative Example 1 since the coupling between the first coil conductor 14 and the second coil conductor 15 was small, the combined inductance L was low and the communication distance was short.
  • Comparative Example 2 the combined inductance L was low and the communication distance was short.
  • Comparative Example 3 the resistance value Rs was high and the communication distance was short.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Coils Or Transformers For Communication (AREA)
  • Details Of Aerials (AREA)
  • Soft Magnetic Materials (AREA)

Abstract

L'invention concerne une antenne magnétique (10) qui comporte : un noyau magnétique (12) dont la forme est un parallélépipède rectangle; et un premier conducteur de bobine (14) et un deuxième conducteur de bobine (15) qui sont enroulés autour du noyau magnétique (12) de manière à être agencés alternativement côte à côte. L'axe d'enroulement du premier conducteur de bobine (14) et du deuxième conducteur de bobine (15) est orthogonal à la direction longue du noyau magnétique (12). Le premier conducteur de bobine (14) et le deuxième conducteur de bobine (15) sont connectés en parallèle.
PCT/JP2016/075537 2015-09-02 2016-08-31 Antenne magnétique et dispositif d'antenne WO2017038885A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS475789Y1 (fr) * 1968-08-15 1972-02-29
JPH0964634A (ja) * 1995-08-22 1997-03-07 Mitsubishi Materials Corp トランスポンダ用アンテナ
JP2005340759A (ja) * 2004-04-27 2005-12-08 Sony Corp アンテナモジュール用磁芯部材、アンテナモジュールおよびこれを備えた携帯情報端末
JP2007019891A (ja) * 2005-07-07 2007-01-25 Toda Kogyo Corp 磁性体アンテナ
JP2014220469A (ja) * 2013-05-10 2014-11-20 Tdk株式会社 複合フェライト組成物および電子部品

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS475789Y1 (fr) * 1968-08-15 1972-02-29
JPH0964634A (ja) * 1995-08-22 1997-03-07 Mitsubishi Materials Corp トランスポンダ用アンテナ
JP2005340759A (ja) * 2004-04-27 2005-12-08 Sony Corp アンテナモジュール用磁芯部材、アンテナモジュールおよびこれを備えた携帯情報端末
JP2007019891A (ja) * 2005-07-07 2007-01-25 Toda Kogyo Corp 磁性体アンテナ
JP2014220469A (ja) * 2013-05-10 2014-11-20 Tdk株式会社 複合フェライト組成物および電子部品

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