JP2017175408A - Antenna device and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device which achieves downsizing and weight reduction while securing high inductance and facilitates assembly, and to provide a manufacturing method of the antenna device.SOLUTION: An antenna device 100 according to one embodiment of the invention includes: an air-core coil 10 having an air-core part 11; a magnetic core 20 having a hollow part 21 and disposed in the air-core part 11 of the air-core coil; and a magnetic shield 30 which has a through hole 31, which communicates with the hollow part 21 of the magnetic core 20, and is provided facing the air-core coil 11.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an antenna device technology.

  In recent years, the spread of contactless communication systems using contactless IC (Integrated Circuit) cards such as traffic tickets and electronic money has been remarkable. An antenna used in a non-contact communication system is required to have a certain inductance because it uses LC resonance. When the antenna is mounted on a portable electronic device such as a smartphone, the inductance can be increased by designing the shape of the antenna into a substantially rectangular shape having the same size as the battery mounted on the electronic device. .

  In general, in order to realize a small coil with high inductance, it is conceivable to use a wire with a thin wire diameter and increase the number of turns. FIG. 1 is a perspective view showing a non-contact power feeding antenna having a conventional structure.

  Alternatively, there is a coil configured such that a spiral conductor (coil) is sandwiched between a nonmagnetic substrate and a soft magnetic sheet, and the material of the soft magnetic sheet is filled in the center of the conductor (for example, , Abstract of patent document 1, description paragraph [0018], see FIG. 1).

Japanese Patent Laid-Open No. 11-16756

  In recent years, contactless communication systems have been introduced especially for wearable applications among portable types, and further miniaturization has been demanded, but it is also necessary to maintain a certain inductance.

  However, in the coil of Patent Document 1, the thickness of the antenna is increased by the thickness of the soft magnetic material sheet, which is contrary to miniaturization. Further, in the coil manufacturing process (assembly), when the coil is sandwiched between the soft magnetic material sheet and the nonmagnetic substrate, there is a drawback that it is difficult to visually recognize the position of the coil.

  An object of the present invention is to provide an antenna device that can achieve miniaturization and weight reduction while ensuring high inductance, and further facilitate assembly, and a method for manufacturing the antenna device.

In order to achieve the above object, an antenna device according to an aspect of the present invention includes an air-core coil, a magnetic core, and a magnetic shield.
The air core coil has an air core part.
The magnetic core has a hollow portion and is disposed in the air core portion of the air core coil.
The magnetic shield has a through hole communicating with the hollow portion of the magnetic core and is provided to face the air-core coil.

  Even if a hollow portion is provided in the magnetic core, the contribution to the decrease in inductance is small. Therefore, it is possible to realize a miniaturized and lightweight antenna device while ensuring high inductance. In addition, since the magnetic shield has a through hole, the position of the air core coil, magnetic core and magnetic shield can be obtained by using a jig having a protrusion that engages with the magnetic core and air core coil through the through hole. Matching can be done easily. That is, the antenna device can be easily assembled.

  The air core coil, the magnetic core, and the magnetic shield may be arranged so that the air core portion, the hollow portion, and the through hole are concentric.

  The hollow portion of the magnetic core may be a through hole or a recess.

  The outer diameter of the magnetic core may be 3 mm or more and 10 mm or less, and the inner diameter of the hollow portion of the magnetic core may be 1 mm or more and 8 mm or less.

  The magnetic shield may include a metal magnetic material or an oxide magnetic material, and the magnetic core may include a metal magnetic material or an oxide magnetic material.

  The antenna device may further include an adhesive layer disposed between the magnetic shield, the air-core coil, and the magnetic core.

  The adhesive layer may be an adhesive resin, an adhesive double-sided tape, or a magnetic sheet having adhesiveness.

  Electronic equipment according to one embodiment of the present invention includes the antenna device.

According to one aspect of the present invention, a method for manufacturing an antenna device includes a magnetic shield and a magnetic core disposed in an air core portion from a side closer to the plate of a jig having a plate and a protrusion on the plate. Placing the magnetic shield, the magnetic core, and the air-core coil on the plate so that the air-core coil is disposed.
After the preceding step, the magnetic shield, the magnetic core, and the air-core coil are pressurized on a plate.
The step described above includes a step of engaging a through hole provided in the magnetic shield and a hollow portion provided in the magnetic core with the protruding portion of the jig.

  By using the jig, it is easy to align the air-core coil, the magnetic core, and the magnetic shield. That is, the antenna device can be easily assembled.

  The step described above may include a step of disposing an adhesive layer between the air-core coil and the magnetic shield.

  As described above, according to the present invention, it is possible to achieve a reduction in size and weight while ensuring a high inductance, and further facilitate assembly.

FIG. 1 is a perspective view showing an antenna apparatus according to a reference example for understanding the technology of the antenna apparatus according to the embodiment of the present invention. 2A is a cross-sectional view taken along line AA ′ in FIG. FIG. 2B is a cross-sectional view showing an antenna device including a coil configured in three layers as another reference example. FIG. 2C is a cross-sectional view showing an antenna device in which a magnetic core is arranged inside a three-layer coil (air core portion) as still another reference example. FIG. 3 is a perspective view showing an antenna apparatus according to an embodiment of the present invention. 4 is a cross-sectional view of the antenna device shown in FIG. FIG. 5 is a diagram for explaining a method of assembling the antenna device. FIG. 6 is a table showing the results of verifying the variation in inductance of the antenna device.

  1. Reference example

  FIG. 1 is a perspective view showing an antenna device according to a reference example for understanding the technology of an antenna device 100 according to an embodiment of the present invention to be described later. In the antenna device 200, as described above, the shape of the coil 10A of the antenna is designed in a substantially rectangular shape having a size equivalent to a battery mounted on an electronic device such as a smartphone as shown in FIG. ing. Thereby, an inductance can be raised.

  2A is a cross-sectional view taken along line AA ′ in FIG. In the antenna device 200, a coil 10 </ b> A is wound around a plate-shaped magnetic shield 13 along the main surface 13 a of the magnetic shield 13. For example, the number of turns of the coil 10A is 12T.

  FIG. 2B shows, as another reference example, a cross section of an antenna device including a coil 10B configured in three layers along the axial direction (vertical direction in the drawing). With this structure, the coil 10B having 12T × 3 = 36T turns can be realized.

  FIG. 2C shows a cross section of an antenna device in which the magnetic core 15 is arranged inside the three-layer coil 10C shown in FIG. 2B (air core portion) as still another reference example. Thereby, even if it is the same number of turns, an inductance and magnetic flux density can be improved.

  In the antenna device shown in FIG. 2C, the alignment accuracy of each component of the coil 10C, the magnetic core 15, and the magnetic shield 13 is important.

  2. Embodiment according to the present invention

  2.1) Configuration of antenna device

  FIG. 3 is a perspective view showing an antenna apparatus according to an embodiment of the present invention. 4 is a cross-sectional view of the antenna device 100 shown in FIG. The antenna device 100 includes an air-core coil 10, a magnetic core 20, an adhesive layer 40, and a magnetic shield 30.

  The air-core coil 10, the magnetic core 20, the adhesive layer 40, and the magnetic shield 30 have a disk shape, but may have a square shape, a rectangular shape, an elliptical shape, or the like.

  A magnetic core 20 having a hollow portion 21 is disposed in the air core portion 11 of the air core coil 10. The air-core coil 10 is configured such that a conducting wire is wound in a plurality of layers in the axial direction (vertical direction in FIG. 4).

  The magnetic shield 30 is provided to face the air-core coil 10 with the adhesive layer 40 interposed therebetween. The magnetic shield 30 has a through hole 31 communicating with the hollow portion 21 of the magnetic core 20.

  The hollow portion 21 of the magnetic core 20 is configured by, for example, a through hole that penetrates the magnetic core 20 in the axial direction.

  As shown in FIG. 4, the air-core coil 10, the hollow portion 21 of the magnetic core 20, and the through-hole 31 of the magnetic shield 30 are substantially concentric with the air-core coil 10. The magnetic core 20 and the magnetic shield 30 are arranged with respect to each other.

  When the air-core coil 10 is thin, the magnetic core 20 is also thin, so that the contribution to the magnetic characteristics is small. However, as the thickness of the air-core coil 10 increases, the contribution of the magnetic core 20 to the magnetic characteristics increases. For example, when the number of coil layers increases, the thickness of the magnetic core 20 increases, and a magnetic path portion with high permeability is formed, so that the magnetic resistance of the antenna device 100 decreases.

  The outer shape of the air core portion 11 of the air core coil 10, the outer shape of the hollow portion 21 of the magnetic core 20, and the outer shape of the through hole 31 of the magnetic shield 30 are, for example, circular. Further, the hole 41 of the adhesive layer 40 is also circular.

  2.2) Material of each member constituting the antenna device

  The magnetic shield 30 is mainly composed of a metal magnetic material or an oxide magnetic material. Fe, Co, Ni, Fe-Ni, Fe-Co, Fe-Al, Fe-Si, Fe-Si-Al, Fe-Ni-Si-Al metal magnetic materials A crystalline or microcrystalline metal magnetic material is used. Alternatively, amorphous metal magnetic materials such as Fe-Si-B, Fe-Si-B-Cr, Co-Si-B, Co-Zr, Co-Nb, or Co-Ta are used. .

  As the oxide magnetic material, hexagonal ferrite such as Mn-Zn, Ni-Zn spinel ferrite, barium ferrite and the like is used.

  Alternatively, the material of the magnetic shield 30 may be a magnetic resin molded body obtained by mixing and molding the metal magnetic powder and / or oxide magnetic powder and a resin. This magnetic resin molded body can contain a filler for improving thermal conductivity, particle filling property and the like. As the magnetic powder, a spherical, slender (cigar type) or flat (disc type) spheroid having a particle size of several μm to 200 μm is used. When reducing magnetic saturation, it is preferable to use a powder having a dimensional ratio (major axis / minor axis) of 7 or less. In this case, not only a single magnetic powder but also powders having different powder diameters, materials, and dimensional ratios may be mixed and used. This magnetic resin molding is produced by applying the mixture to PET or the like and drying it with hot air, or by high-pressure molding (powder molding) or the like.

  A composite structure or a laminated structure in which a plurality of magnetic bodies made of the above materials are combined may be used.

  The magnetic core 20 is also made of the same material (metal magnetic material or oxide magnetic material) as the magnetic shield 30. When a sheet-like or ribbon-like material is used as the material of the magnetic core 20, it may be formed rounded like a spring.

  Both the magnetic shield 30 and the magnetic core 20 may be a metal magnetic material or an oxide magnetic material. Alternatively, the magnetic shield 30 may be a metal magnetic material and the magnetic core 20 may be an oxide magnetic material, or vice versa.

  As the adhesive layer 40, for example, an adhesive (adhesive) double-sided tape is used. Alternatively, an applied adhesive resin is used. Or the magnetic sheet which has the thermosetting adhesiveness which mixed magnetic powder and resin can be used.

  2.3) Manufacturing method (assembly method) of antenna device

  The assembly method described below may be performed manually by an operator or may be automated by a robot.

  FIG. 5 is a diagram for explaining a method of assembling the antenna device 100. A jig 50 is used for manufacturing the antenna. The jig 50 includes a plate 51 and a protrusion 53 that protrudes in one direction from the upper surface of the plate 51.

  The protrusion 53 regulates the position of each member (here, for example, the magnetic shield 30, the magnetic core 20, and the adhesive layer 40) constituting the antenna device 100. The outer diameter of the protrusion 53 is substantially the same as the size of the through hole 31 of the magnetic shield 30, the hollow part 21 of the magnetic core 20, and the hole 41 of the adhesive layer 40. The height of the protrusion 53 is higher than the thickness of the antenna device 100. It is desirable that the protruding portion 53 is configured to be lowered in height when pressed in the axial direction, like a pogo pin.

  The magnetic shield 30, the adhesive layer 40, and the magnetic core 20 are configured so that the through hole 31 of the magnetic shield 30, the hole 41 of the adhesive layer 40, and the hollow portion 21 of the magnetic core 20 are engaged with the protrusion 53 of the jig 50. , And the air-core coil 10 are placed on the plate 51 in this order. Each member may be placed on the plate 51 after the magnetic core 20 is incorporated in the air core portion 11 of the air core coil 10 in advance.

  After placing each member on the plate 51, the air core coil 10 (and the magnetic core 20) is pressurized on the plate 51 from above, whereby the antenna device 100 is completed. When the protrusion 53 is a pogo pin, the height is lowered (retracted) when pressed, so that the air-core coil 10 and the magnetic core 20 can be surely pressed, and these are magnetically shielded 30 via the adhesive layer 40. Can be glued to.

  If the air core coil 10 and the magnetic core 20 are greatly different in thickness, it is difficult for the thinner member to be pressed. Therefore, it is preferable that the thicknesses of the air-core coil 10 and the magnetic core 20 are designed to be substantially equal.

  As described above, according to the assembling method according to the present embodiment, the use of the jig 50 having the protrusions 53 makes it easy to align each member. In addition, the alignment accuracy is high.

  That is, according to the antenna device 100 according to the present embodiment, even if the magnetic core 20 is provided with the hollow portion 21, the contribution to the decrease in inductance is small. The antenna device 100 can be realized. Moreover, as described above, alignment during assembly can be performed easily and with high accuracy.

  In the above assembly method, a form using a double-sided tape as the adhesive layer 40 is shown. However, when a thermosetting resin or a thermosetting sheet is used as the adhesive layer 40, heat is applied to the antenna device 100 during or after the bonding. You may make it perform the thermocompression bonding which adds heat at the time of the said pressurization.

  3. Verification of variation in inductance of antenna device

  The present inventor conducted an electromagnetic field simulation of the antenna device 100 in order to verify the effect of the present invention. Maxis of Ansys was used as a simulator. The structure of the antenna device 100 according to the embodiment shown in FIGS. 3 and 4 was used as an analysis model. The size and characteristics of each member common to each comparative example and each example are as follows. In addition, the magnetic permeability here is represented by the relative magnetic permeability.

Magnetic shield 30 outer diameter: 10mm
Magnetic shield 30 thickness: 0.4mm
Magnetic permeability of magnetic shield 30: 29
Magnetic core 20 outer diameter: 5 mm
Air core coil 10 wire diameter: 0.25mm
Number of turns of air-core coil 10: 24T (1 layer 8T x 3 layers)
Outer diameter of adhesive layer 40 (magnetic adhesive sheet): 10 mm
Adhesion layer 40 (magnetic adhesive sheet) thickness: 0.05 mm

  In the analysis, the variation of the inductance at 100 kHz was verified by changing the inner diameter and the magnetic permeability of the magnetic core 20. FIG. 6 is a table summarizing the analysis results. In this table, the variation of the antenna device not having the magnetic core 20 is expressed in% with reference to the inductance (0%).

  In the table, antenna devices according to comparative examples are indicated by A, B, F, and J. The magnetic cores of Comparative Examples B, F, and J did not have a hollow portion, and the shape thereof was set to a solid disk shape.

  The inner diameters of the magnetic cores of Examples C, D, and E (the diameter of the hollow portion 21; the same applies hereinafter) are 1.5 mm, 3 mm, and 4 mm, respectively. Similarly, the inner diameters of the magnetic cores of Examples G, H, and I are 1.5 mm, 3 mm, and 4 mm, respectively. The inner diameters of the magnetic cores of Examples K and L are 1.5 mm and 3 mm, respectively.

  The outer diameter of the magnetic core is typically 5 mm, but may be, for example, 3 mm or more and 10 mm or less, and more preferably 4 mm or more and 7 mm or less. In that case, the inner diameter of the magnetic core may be 1 mm or more and 8 mm or less, and more preferably, the inner diameter is 1.5 mm or more and 5 mm or less.

  Moreover, the magnetic permeability of the magnetic cores of Comparative Example B, Examples C, D, and E is 10 respectively. The magnetic permeability of the magnetic cores of Comparative Example F, Examples G, H, and I is 29, respectively. The magnetic permeability of the magnetic cores of Comparative Example J and Examples K and L is 100 respectively.

  From the table, it can be seen that the higher the magnetic core permeability, the higher the inductance. The inductances of Comparative Examples B, F, J, Examples C, D, E, G, H, I, K, and L are 20% or more higher than the inductance of Comparative Example A.

  In Examples E and I, if the inner diameter of the magnetic core is too large, an increase in inductance is suppressed. This can be explained as a decrease in the cross-sectional area of the magnetic path. If the inner diameter of the magnetic core is about 3 mm as in Examples D, H, and L, the inductance decrease is slight.

  Therefore, even if a hole is provided in each central portion of the magnetic shield 30, the magnetic core 20, and the adhesive layer 40, it can be said that the influence on the magnetic characteristics is limited.

  On the other hand, in Comparative Examples B, F, and J, an increase in inductance of 20% or more can be confirmed, but since the magnetic core does not have a hollow portion, the antenna device can be easily assembled as described in the above assembly method. I can't.

  Therefore, in the antenna device 100 according to this embodiment, the magnetic core 20 is provided with the hollow portion 21, and the magnetic shield 30 is also provided with the through hole 31 communicating with the hollow portion 21. It can be said. As a result, it is possible to realize the antenna device 100 that is small, light, high inductance, and easy to assemble.

  4). Other variations

  The present invention is not limited to the embodiment described above, and other various embodiments can be realized.

  For example, the outer shape of each of the air core portion 11 of the air core coil 10, the hollow portion 21 of the magnetic core 20, the hole 41 of the adhesive layer 40, and the through hole 31 of the magnetic shield 30 is an ellipse or a polygon other than a circle. May be. Basically, according to the outer shapes of the air core coil 10, the magnetic core 20, and the magnetic shield 30, the outer shapes of the air core portion 11, the hollow portion 21, the hole 41, and the through hole 31 are also determined. Of course, the outer shape of each member may be different from the shape of the air core part 11, the hollow part 21, the through hole 31, and the like.

  In the above embodiment, the hollow portion 21 of the magnetic core 20 is a hole that penetrates in the axial direction, but may be a recess that does not penetrate. Even if the hollow portion 21 of the magnetic core 20 is a recess, for example, if the protrusion 53 of the plate 51 can be engaged with the recess, the ease of assembly can be improved as in the above embodiment. A plurality of the recesses may be provided, and a plurality of protrusions of the jig may be provided accordingly.

  The antenna device 100 according to the embodiment can be mounted on an electronic device such as a smartphone, a tablet device, or a wearable device.

  It is also possible to combine at least two feature portions among the feature portions of each embodiment described above.

DESCRIPTION OF SYMBOLS 10 ... Air core coil 11 ... Air core part 20 ... Magnetic core 21 ... Hollow part 30 ... Magnetic shield 31 ... Through-hole 40 ... Adhesive layer 41 ... Hole 50 ... Jig 51 ... Plate 53 ... Projection part 100 ... Antenna apparatus

Claims (10)

An air core coil having an air core part;
A magnetic core having a hollow portion and disposed in an air core portion of the air core coil;
An antenna device comprising: a magnetic shield having a through hole communicating with a hollow portion of the magnetic core and provided to face the air-core coil. The antenna device according to claim 1,
The antenna device, wherein the air core coil, the magnetic core, and the magnetic shield are arranged so that the air core portion, the hollow portion, and the through hole are concentric. The antenna device according to claim 1 or 2,
The hollow portion of the magnetic core is a through hole or a recess. Antenna device. The antenna device according to any one of claims 1 to 3,
The outer diameter of the magnetic core is 3 mm or more and 10 mm or less,
An antenna device in which an inner diameter of a hollow portion of the magnetic core is 1 mm or more and 8 mm or less. The antenna device according to any one of claims 1 to 4,
The magnetic shield includes a metal magnetic material or an oxide magnetic material,
The magnetic core includes a metal magnetic material or an oxide magnetic material. The antenna device according to any one of claims 1 to 5,
An antenna device further comprising: an adhesive layer disposed between the magnetic shield and the air-core coil and the magnetic core. The antenna device according to any one of claims 1 to 6,
The antenna layer is an adhesive resin, an adhesive double-sided tape, or an adhesive magnetic sheet. An air core coil having an air core part;
A magnetic core having a hollow portion and disposed in an air core portion of the air core coil;
An electronic apparatus comprising an antenna device having a through hole communicating with a hollow portion of the magnetic core and having a magnetic shield provided to face the air-core coil. On the plate, a magnetic shield and an air-core coil having a magnetic core disposed in the air-core portion are arranged from the side close to the plate of a jig having a plate and a protrusion on the plate. Placing the magnetic shield, the magnetic core, and the air-core coil;
Pressing the magnetic shield, the magnetic core, and the air-core coil on a plate after the step of the previous placement;
The step described above includes a step of engaging a through hole provided in the magnetic shield and a hollow portion provided in the magnetic core with the protruding portion of the jig. It is a manufacturing method of the antenna device according to claim 9,
The step described above includes a step of arranging an adhesive layer between the air-core coil and the magnetic shield.

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