Antenna coil

Abstract

To reduce the size and weight of an antenna coil.SOLUTION: An antenna coil 100 comprises: a core 110 that comprises a composite of a plurality of materials including a powdery soft magnetic material and a non-metal material; and a coil 120 arranged so as to be wound around the core 110.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an antenna coil. [Background technology]

[0002] An antenna coil used in an antenna in a device for performing wireless communication, etc., includes a core and a winding wound around the core. Patent Document 1 describes the use of a rod-shaped ferrite core as the core used in such an antenna coil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4134173 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a rod-shaped ferrite core is used as the core as described in Patent Document 1, the core is prone to cracking, making it difficult to make the core thin, and therefore making it difficult to reduce the size and weight of the coil.

[0005] The present invention has been made in consideration of the above problems, and has an object to make it possible to reduce the size and weight of an antenna coil. [Means for solving the problem]

[0006] The antenna coil of the present invention First example of is an antenna coil for at least one of transmitting and receiving a radio signal, comprising a core made of a composite of multiple types of materials including a powdered soft magnetic material and a non-metallic material, and a winding arranged in a wound state around the core. The volume ratio of the powdered soft magnetic material to the volume of the core is 5 vol% or more and 95 vol% or less. do. A second example of the antenna coil of the present invention is an antenna coil for at least one of transmitting and receiving radio signals, comprising: a core comprising a composite of multiple types of materials including a powdered soft magnetic material and a non-metallic material; and a winding arranged in a wound state around the core, wherein the core comprises a molded product having multiple types of materials including the powdered soft magnetic material and the non-metallic material, and the density of the core, expressed as the value obtained by dividing the mass of the core by the volume of a region of a mold used to mold the multiple types of materials and into which the multiple types of materials are inserted, is 1 g / cm.3 More than 9g / cm 3 The following is the result. [Effects of the Invention]

[0007] According to the present invention, the antenna coil can be made smaller and lighter. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram (perspective view) showing an example of the configuration of an antenna coil. [Figure 2] FIG. 2 is a diagram (cross-sectional view) showing an example of the configuration of an antenna coil. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the comparison of length, position, size, spacing, etc. being the same not only means that the objects are exactly the same, but also includes differences (for example, differences within the tolerances established at the time of design) that do not deviate from the gist of the invention (the extent to which the purpose of the invention can be achieved). The xyz coordinates shown in each figure indicate the relationship of the orientations in each figure. A symbol with a cross mark (×) inside a white circle (○) indicates an arrow pointing from the front to the back of the page, and a symbol with a black circle (●) inside a white circle (○) indicates an arrow pointing from the back to the front of the page.

[0010] Fig. 1 is a diagram showing an example of the configuration of an antenna coil 100, and is a perspective view showing a state in which the antenna coil 100 is viewed from above. Fig. 2 is a diagram showing an example of the configuration of an antenna coil, and is a cross-sectional view of the antenna coil 100. Fig. 2(a) is a cross-sectional view taken along line II of Fig. 2(c), Fig. 2(b) is a cross-sectional view taken along line II-II of Fig. 2(c), and Fig. 2(c) is a cross-sectional view taken along line II of Fig. 2(a).

[0011] 1 and 2, the antenna coil 100 is a coil for at least one of transmitting and receiving radio signals, and includes a core 110, a winding 120, and a case 130. The antenna coil 100 constitutes part of an antenna, and is a coil that serves as at least one of the receiving end and transmitting end of radio signals.

[0012] <Core 110> The core 110 includes a composite (a single object made up of multiple materials) including a powdered soft magnetic material and a non-metallic material. The composite is, for example, a molded product made up of a mixture of multiple materials and molded into a single object. In this embodiment, the core 110 is illustrated as a molded product made up of a mixture of multiple materials. It should be noted that molding means forming using a mold, but shaping means that it is not limited to forming using a mold.

[0013] The powdered soft magnetic material may be any magnetic material with soft magnetic properties, including at least one of powdered Fe-based amorphous alloy material, powdered Fe-based nanocrystalline alloy material, powdered pure iron, powdered ferrite, powdered Permalloy, and powdered silicon steel. By using powdered soft magnetic material, it is possible to realize a thinner and smaller core than a ferrite core formed by sintering without powdering. Fe-based amorphous alloy material, Fe-based nanocrystalline alloy material, pure iron, and silicon steel have higher Curie temperatures than ferrite. Therefore, using at least one of powdered Fe-based amorphous alloy material, powdered Fe-based nanocrystalline alloy material, powdered pure iron, and powdered silicon steel as the powdered soft magnetic material can suppress inductance degradation even in high-temperature environments. Furthermore, Fe-based amorphous alloy material, Fe-based nanocrystalline alloy material, pure iron, and silicon steel have higher saturation magnetic flux densities than ferrite. Therefore, by using at least one of powdered Fe-based amorphous alloy material, powdered Fe-based nanocrystalline alloy material, powdered pure iron, and powdered silicon steel material as the powdered soft magnetic material, the number of turns of the winding 120 can be reduced (if the magnetic flux density in the core is the same), and the antenna coil 100 can be made smaller and lighter.

[0014] For the above reasons, the powdered soft magnetic material may be any powdered soft magnetic material. For example, it is preferable to include at least one of powdered Fe-based amorphous alloy material, powdered Fe-based nanocrystalline alloy material, powdered pure iron, powdered ferrite, and powdered silicon steel. It is more preferable to include at least one of powdered Fe-based amorphous alloy material, powdered Fe-based nanocrystalline alloy material, powdered pure iron, and powdered silicon steel. Furthermore, when it is important to facilitate the manufacture of the core 110, the powdered soft magnetic material is preferably only one of powdered Fe-based amorphous alloy material, powdered Fe-based nanocrystalline alloy material, powdered pure iron, powdered ferrite, and powdered silicon steel. It is more preferable to include only one of powdered Fe-based amorphous alloy material, powdered Fe-based nanocrystalline alloy material, powdered pure iron, powdered ferrite, and powdered silicon steel. However, the powdered soft magnetic material may include at least two of powdered Fe-based amorphous alloy material, powdered Fe-based nanocrystalline alloy material, powdered pure iron, powdered Permalloy, powdered silicon steel material, etc. For example, in order to make the core lighter in weight than a ferrite core and to have characteristics that utilize the advantages of each material, the powdered soft magnetic material may include at least two of powdered Fe-based amorphous alloy material, powdered Fe-based nanocrystalline alloy material, powdered pure iron, powdered Permalloy, powdered silicon steel material, etc.

[0015] When using an Fe-based nanocrystalline alloy as a soft magnetic material, the composition of the starting material for the Fe-based nanocrystalline alloy can be determined according to the properties required for the Fe-based nanocrystalline alloy. The composition of the starting material for the Fe-based nanocrystalline alloy can be determined according to the properties required for the Fe-based nanocrystalline alloy, for example, using the following composition formula: Fe 100-(a+b+c) -Si a -B b -M c (atom%) 4≦a≦18, 4≦b≦12, 0.5≦c≦10 M is an element group containing at least one element selected from Cu, Nb, Mo, Ta, W, Ti, V, Cr, Mn, Zr, Hf, Y, Al, C, and P.

[0016] In the above composition, a part of Fe may be replaced with 10 atomic % or less of Ni or 10 atomic % or less of Co.

[0017] When bccFe crystals are generated in an Fe-based nanocrystalline alloy material produced by heat treatment or the like on the starting materials, the αFe crystal size is preferably 1 nm or more and 1000 nm or less. The αFe crystal size is, for example, preferably less than 1000 nm, more preferably less than 500 nm, and even more preferably less than 100 nm. The crystal size is calculated, for example, from the half-width of the peak of the diffraction line obtained by X-ray diffraction. Furthermore, even if an amorphous Fe-based nanocrystalline alloy material in which bccFe crystals are not generated is produced without heat treatment of the starting material, a high magnetic permeability can be obtained as the core. Therefore, although heat treatment of the starting material is generally preferred, it is not necessary to heat treat the starting material. By not heat treating the starting material, an amorphous Fe-based nanocrystalline alloy material without bccFe crystals can be produced, which prevents the Fe-based nanocrystalline alloy material from becoming brittle. This improves the mechanical strength of the core 110. In addition, to improve the magnetic properties, a magnetic field may be applied to the starting material during the heat treatment process, but it is not necessary to apply a magnetic field to the starting material during the heat treatment process. Furthermore, when the Fe-based nanocrystalline alloy material is used as powder, an insulator (e.g., oxide such as an oxide film and / or nitride) may be formed on the powder surface to reduce eddy current loss in the core, thereby ensuring insulation between the powder particles and between the powder and materials other than the powder.

[0018] When using an Fe-based amorphous alloy as the soft magnetic material, the composition of the starting material for the Fe-based amorphous alloy can be determined according to the properties required of the Fe-based amorphous alloy. Examples of the composition formula are as follows: Fe 100-(a+b+c) -Si a -B b -M c (atom%) 4≦a≦14, 6≦b≦16, 0≦c≦6 M is an element group containing at least one element selected from Cu, Nb, Mo, Ta, W, Ti, V, Cr, Mn, Zr, Hf, Y, Al, C, and P. In the above composition, a part of Fe may be replaced with 10 atomic % or less of Ni or 10 atomic % or less of Co.

[0019] When bccFe crystals are generated in the Fe-based amorphous alloy material produced by heat treatment or the like on the starting materials, the crystal size of the bccFe crystals is preferably 0.1 μm or more and 5000 μm or less. The crystal size of the bccFe crystals in the Fe-based amorphous alloy material after the heat treatment process is, for example, preferably less than 100 μm, more preferably less than 50 μm, and even more preferably less than 10 μm. The crystal size is, for example, a value calculated from the half-width of the peak of the diffraction line obtained by X-ray diffraction. Furthermore, depending on the application, by performing stress relief annealing on the core, the required magnetic permeability can be obtained without performing heat treatment on the starting material to obtain good magnetic properties. Therefore, although heat treatment on the starting material is ideal, heat treatment on the starting material is not necessary. By not subjecting the starting material to heat treatment, an Fe-based amorphous alloy material that does not contain bccFe crystals can be obtained, thereby preventing the Fe-based amorphous alloy material from becoming brittle. This improves the mechanical strength of the core 110. Although a magnetic field may be applied to the starting material during the heat treatment process to improve the magnetic properties of the core, it is not necessary to apply a magnetic field to the starting material during the heat treatment process. When using an Fe-based amorphous alloy material as powder, an insulating material (e.g., an oxide such as an oxide film and / or a nitride) may be formed on the powder surface to reduce eddy current loss in the core, thereby ensuring insulation between the powder particles and between the powder and materials other than the powder.

[0020] The particle size (diameter) of the powdered soft magnetic material is preferably in the range of 0.01 μm to 2 mm. The particle size of the powdered soft magnetic material can be determined by measuring the geometric mean diameter using a microscope. For example, when the geometric mean diameter is measured as the minor axis diameter, major axis diameter, and biaxial mean diameter (the arithmetic mean value of the minor axis diameter and the major axis diameter), the particle size of the powdered soft magnetic material may be the biaxial mean diameter.

[0021] A first specific example of a method for measuring the geometric mean diameter is a method in which the particle diameters of particles present within the field of view of an optical microscope, a scanning electron microscope (SEM (Scanning Electron Microscope)), or a transmission electron microscope (TEM (Transmission Electron Microscope) / AEM (Analytical Electron Microscope)) are directly measured. A second specific example of a method for measuring the geometric mean diameter is a method in which the geometric mean diameter (e.g., light scattering diameter, spherical equivalent diameter) is measured using a light scattering and diffraction method. In the second specific example, for example, a particle size distribution measuring device is used to observe the movement of Brownian motion as light intensity by light scattering and laser diffraction, and the particle diameter is calculated from the light intensity.

[0022] The powdered soft magnetic material may be spherical or have another shape. However, to increase the magnetic permeability of the core 110, it is preferable that the shape be complex, with differences in the minor axis diameter, major axis diameter, and thickness. For example, it is preferable that the ratio of the major axis diameter to the minor axis diameter be 1 or greater, or that the ratio of the major axis diameter to the thickness be 1 or greater.

[0023] The non-metallic material is used to increase the electrical resistance of the core 110 (preferably by making the core 110 an insulator), improve the impact resistance of the core 110, facilitate molding of the core 110, and reduce the cost of the core 110. The non-metallic material contained in the core 110 is not particularly limited, but preferably has a heat resistance temperature that is equal to or higher than the maximum temperature expected for the core during the manufacturing process, which is the temperature rise caused by heat applied during the manufacturing process. For example, the heat resistance temperature of the non-metallic material is preferably 250°C or higher. Furthermore, the non-metallic material is preferably an insulating material. Non-metallic materials include, for example, thermoplastic resins, general-purpose plastics (e.g., polyethylene (PE), polystyrene (PS), AS resin (AS or SAN), ABS resin (ABS), polypropylene (PP), polyvinyl chloride resin (PVC), methacrylic resin (PMMA), polyethylene terephthalate (PET)), general-purpose engineering plastics (e.g., polyamide (PA), polycarbonate (PC), polyacetal (POM), modified polyphenylene ether (m-PPE), polybutylene terephthalate (PBT)), super engineering plastics (e.g., polyphenylene sulfide (PPS), polysulfone (PSU), polyethersulfone (PES), polya Examples of suitable materials include polyimide (PAI), polyether ether ketone (PEEK), and liquid crystal polymer (LCP), thermosetting resins (e.g., phenolic resin (PF), urea resin (UF), melamine resin (MF), epoxy resin (EP), unsaturated polyester resin (UP), polyurethane (PU), diallyl phthalate resin (PDAP), silicone resin (SI), and alkyd resin polyphenylene sulfide (PPS)), as well as ceramics (e.g., zirconia (ZrO), alumina (AlO), silicon carbide (SiC), aluminum nitride (AlN), silicon nitride (SiN), boron nitride (BN), quartz glass (SiO), and Macol (fluorphlogopite). Other examples of suitable non-metallic materials include fluororesins, thermoplastic elastomers, polymethylpentene (PMP), biodegradable plastics, and cellulose-based plastics. The non-metallic material may also be, for example, a mixture of two or more of the above materials.

[0024] Next, an example of a method for manufacturing the core 110 will be described. The method for producing the powdered soft magnetic material is not particularly limited. It is sufficient to produce the powdered soft magnetic material by a known method. When using an Fe-based nanocrystalline alloy material and / or an Fe-based amorphous alloy material as the soft magnetic material, the Fe-based nanocrystalline alloy material and / or the Fe-based amorphous alloy material may be produced as a thin ribbon by, for example, a liquid quenching method, a spinning method in a rotating liquid, or a sputtering method.

[0025] The soft magnetic material is then pulverized. There are no particular limitations on the method for pulverizing the soft magnetic material. The soft magnetic material may be pulverized by a known method. For example, the soft magnetic material may be pulverized using an atomization method (water atomization or gas atomization) or a mechanical pulverization method (ball mill, mixer mill, attritor, etc.).

[0026] Then, a plurality of materials including the powdered soft magnetic material and the non-metallic material are mixed. Although the method for mixing the powdered soft magnetic material and the plurality of materials including the non-metallic material is not particularly limited, the following method can be given as a specific example.

[0027] First, the material to be mixed with the powdered soft magnetic material (material including a non-metallic material) is pulverized using a mixer or the like. This is to ensure that the material to be mixed with the powdered soft magnetic material (material including a non-metallic material) is mixed with the powdered soft magnetic material as evenly as possible. Furthermore, when resin is used as the non-metallic material, mixing the resin with the powdered soft magnetic material without pulverizing it may result in the formation of lumps of resin alone (so-called lumps) in the core 110 (composite). This may result in the powdered soft magnetic material and the powdered resin separating from each other. When resin is used as the non-metallic material, preventing this separation is another reason why it is preferable to pulverize the material to be mixed with the powdered soft magnetic material (material including a non-metallic material) before mixing it with the powdered soft magnetic material.

[0028] In addition to the non-metallic material, the material to be mixed with the powdered soft magnetic material preferably includes at least one of a curing agent, a curing accelerator, a dispersant, and a release agent. The curing agent is a material that hardens the material when heat is applied to the material to mold the composite described below. The curing accelerator is a material that accelerates the hardening of the material. The dispersant is a material that increases the fluidity of the powdered soft magnetic material and promotes dispersion of the powdered soft magnetic material. The dispersant includes, for example, spherical silica particles. The release agent is a material that facilitates separation of the composite (molded product) from the mold used to mold the composite described below when removing the composite (molded product). The material to be mixed with the soft magnetic material may be in powder or liquid form. In the following description, the material (including the non-metallic material) that is pulverized as described above and mixed with the powdered soft magnetic material will be referred to as a non-soft magnetic mixed material as necessary.

[0029] The non-soft magnetic mixed material obtained as described above is mixed using a kneader, etc. At this time, it is preferable that the materials contained in the non-soft magnetic mixed material are mixed as uniformly as possible (i.e., the materials are distributed (dispersed) as uniformly as possible in the non-soft magnetic mixed material).

[0030] In the following description, a material obtained by mixing a powdered soft magnetic material with a silane coupling agent as a dispersant will be referred to as a soft magnetic mixed material as necessary. The silane coupling agent is an example of a material (adhesive) for improving the adhesion between the powdered soft magnetic material and a non-metallic material. Because the silane coupling agent is liquid, it tends to form lumps (so-called clumps). For this reason, it is preferable to mix the powdered soft magnetic material and the silane coupling agent so that no lumps are formed in the soft magnetic mixed material. It is also preferable to mix the powdered soft magnetic material and the silane coupling agent as uniformly as possible (i.e., the powdered soft magnetic material and the silane coupling agent are distributed (dispersed) as uniformly as possible in the soft magnetic mixed material).

[0031] Based on a predetermined volume ratio of the powdered soft magnetic material to the volume of the core 110, the mass ratio of the non-soft magnetic mixed material to the mass of the soft magnetic mixed material is calculated, and the masses of the soft magnetic mixed material and the non-soft magnetic mixed material are calculated and determined based on the calculated mass ratio. Here, the volume ratio of the powdered soft magnetic material to the volume of the core 110 is preferably 5 vol% or more and 95 vol% or less from the viewpoint of stabilizing the shape of the core 110, and more preferably 25 vol% or more and 85 vol% or less from the viewpoint of ease of molding. The determined masses of the soft magnetic mixed material and the non-soft magnetic mixed material are then mixed using a high-speed mixer or the like. In the following description, a material obtained by mixing the soft magnetic mixed material and the non-soft magnetic mixed material will be referred to as the soft-magnetic-non-soft magnetic mixed material as necessary. As mentioned above, the silane coupling agent is liquid and therefore prone to forming lumps (so-called clumps). For this reason, it is preferable to mix the soft magnetic mixed material and the non-soft magnetic mixed material so that the soft-magnetic-non-soft magnetic mixed material does not contain lumps. It is also preferable that the soft magnetic mixed material and the non-soft magnetic mixed material are mixed as uniformly as possible (i.e., that the soft magnetic mixed material and the non-soft magnetic mixed material are distributed (dispersed) as uniformly as possible in the soft magnetic / non-soft magnetic mixed material).

[0032] The soft-magnetic / non-soft-magnetic mixed material is then inserted into a groove (recessed region) of a mold (jig), and the soft-magnetic / non-soft-magnetic mixed material is molded using a heat press or the like. When a heat press is used for molding, it is preferable to raise the temperature of the heat press (heating plate (plate for applying pressure to the object to be pressed)) to the temperature at which pressure will be applied prior to molding. It is also preferable to raise the temperature of the mold to the temperature at which pressure will be applied prior to inserting the soft-magnetic / non-soft-magnetic mixed material. This temperature increase is performed to perform heat and pressure molding on the soft-magnetic / non-soft-magnetic mixed material so that voids in the soft-magnetic / non-soft-magnetic mixed material become small and few (preferably, no) at all. From this perspective, for example, the set temperature during pressure application of at least one of the heat press and the mold may be set to a value that causes the temperature of the soft-magnetic / non-soft-magnetic mixed material during pressure application to be equal to or higher than the melting point of the non-metallic material and lower than the melting point of the powder soft magnetic material. In this way, the temperature of the soft-magnetic / non-soft-magnetic mixed material during pressurization is equal to or higher than the melting point of the non-metallic material but lower than the melting point of the powdered soft magnetic material, thereby melting the non-metallic material. In this case, for example, the temperature (set value) of at least one of the heat press and mold during pressurization may be set to, for example, the melting point of the non-metallic material. That is, for example, if the melting point of the non-metallic material is 180°C, the temperature (set value) of at least one of the heat press and mold during pressurization may be set to 180°C. However, it is not necessary to adopt a set value for the temperature of at least one of the heat press and mold during pressurization such that the temperature of the soft-magnetic / non-soft-magnetic mixed material during pressurization is equal to or higher than the melting point of the non-metallic material but lower than the melting point of the powdered soft magnetic material. For example, the set value for the temperature of at least one of the heat press and mold during pressurization may be a set value for the temperature of the soft-magnetic / non-soft-magnetic mixed material during pressurization such that the temperature is lower than the melting points of the powdered soft magnetic material and the non-metallic material. In this case, the temperature of the soft magnetic / non-soft magnetic mixed material when pressed is lower than the melting points of the powdered soft magnetic material and non-metallic material, so melting of the soft magnetic material can be prevented even when using a non-metallic material with a high melting point. In this case, the material containing the powdered soft magnetic material and non-metallic material is compacted without melting, so the soft magnetic / non-soft magnetic mixed material becomes a so-called sintered body.Even in this way, it is possible to perform powder compaction on the soft magnetic / non-soft magnetic mixed material so that the voids in the soft magnetic / non-soft magnetic mixed material are small and few (preferably none). Furthermore, if it is possible to make the voids in the soft magnetic / non-soft magnetic mixed material small and few (preferably none), then depending on the materials that make up the soft magnetic / non-soft magnetic mixed material, it is also possible to perform powder compaction on a material containing a powdered soft magnetic material and a non-metallic material without heating a hot press or mold. The molding method for soft-magnetic / non-soft-magnetic mixed materials is not limited to hot press molding. Other molding methods include compression molding, injection molding, blow molding, extrusion molding, vacuum molding, and compressed air molding. A magnetic field may also be applied to the soft-magnetic / non-soft-magnetic mixed material during molding. Applying a magnetic field can align the magnetic domains of the filled powdered soft magnetic material in the direction of the applied magnetic field, achieving uniform or anisotropic dispersion of the powdered soft magnetic material within the molded product (soft-magnetic / non-soft-magnetic mixed material after molding). This can also improve the quality of the molded product and control the magnetization direction of the molded product by giving it an easily or difficultly magnetized direction. After molding of the soft and non-soft magnetic mixed material is completed and the mold is cooled, the molded product of the soft and non-soft magnetic mixed material manufactured as described above is removed from the mold. A magnetic field may also be applied to the molded product (soft and non-soft magnetic mixed material (core) after molding) to improve its magnetic properties.

[0033] The size of the core 110 (molded product) manufactured as described above is not particularly limited, but is preferably as follows, taking into consideration the installation space of the device in which the antenna coil 100 is installed. That is, the length of the core 110 (molded product) (the length in the direction parallel to the winding axis of the winding 120 (y-axis direction)) is preferably in the range of 1 mm to 300 mm. The thickness of the core 110 (the length in the height direction of the antenna coil 100 (z-axis direction)) is preferably in the range of 0.5 mm to 100 mm. The width of the core 110 (molded product) (the length in the x-axis direction) is preferably in the range of 1 mm to 300 mm. Furthermore, the length of the core 110 is preferably in the range of 0.003 to 300 times the width, and the thickness of the core 110 is preferably in the range of 0.015 to 100 times the width.

[0034] 1 and 2 show an example in which the shape of the core 110 (molded product) is a rectangular parallelepiped. However, the shape of the core (molded product) is not limited to a rectangular parallelepiped, and may be other shapes. Examples of the shape of the core 110 include shapes that satisfy both of the following (a) and (b). (a) A shape in which the surface area other than the edge portion (the boundary between two adjacent surfaces) is made up of flat and curved surfaces, a shape in which the surface area other than the edge portion is made up of (only) flat surfaces, or a shape in which the surface area other than the edge portion is made up of (only) curved surfaces. Note that the edge portion may or may not have curvature (it may or may not be curved (bent)). (b) Shapes without rotational symmetry or shapes with rotational symmetry. An example of a shape with rotational symmetry is an n-sided prism (n is an integer of 3 or greater). Note that rotational symmetry refers to n-fold symmetry (n is an integer of 2 or greater) with the center line of core 110 (a virtual line that passes through the center of gravity of core 110 and extends in a direction parallel to the winding axis of winding 120) as the axis of rotational symmetry. In this embodiment, the core 110 is formed by mixing and molding a plurality of types of materials, which has the advantage that the core 110 can be formed into a variety of shapes.

[0035] Furthermore, if the density of the core 110 is too low (i.e., the pressure applied during molding is too low), moldability may be reduced. On the other hand, if the density of the core 110 is too high (i.e., the pressure applied during molding is too high), the electrical characteristics (inductance L, quality factor Q, etc.) of the antenna coil 100 may be reduced. From this perspective, the density of the core 110 is set to 1 g / cm 3 More than 9g / cm 3 The true density of the soft magnetic material (before pulverization) is preferably 5 g / cm or less. 3 More than 10g / cm 3 Preferably, the true density of the non-metallic material is 0 g / cm or less. 3 Super 4g / cm 3 Preferably, it is:

[0036] Here, the density of the core 110 is expressed as the mass of the core 110 divided by the volume of a region of the mold used to mold multiple types of materials (in this embodiment, the soft magnetic / non-soft magnetic mixed material) into which the multiple types of materials are inserted (= mass / volume). In the following description, the region of the mold used to mold multiple types of materials (in this embodiment, the soft magnetic / non-soft magnetic mixed material) into which the multiple types of materials are inserted will be referred to as the material insertion region of the mold as necessary. The material insertion region of the mold is preferably the region into which the multiple materials are actually inserted out of the entire region of the mold recess into which the multiple types of materials can be inserted. However, for simplicity, the entire region of the mold recess into which the multiple materials can be inserted may also be referred to as the material insertion region of the mold.

[0037] <Winding 120> The winding 120 is wound around the core 110 (surrounding the core 110). The winding 120 is realized by known techniques, such as using an insulating metal wire (e.g., enameled copper wire or polyurethane copper wire). FIGS. 1 and 2 illustrate an example in which the direction parallel to the winding axis of the winding 120 (the direction parallel to the central axis (center line) of the antenna coil 100) is parallel to the y-axis. For ease of illustration, the number of turns of the winding 120 is shown in FIGS. 1 and 2 as being fewer than the actual number. Ends 121a and 121b of the winding 120 are electrically connected to an external circuit including a resonance capacitor (not shown). The winding 120 may have multiple partial windings. In this case, the ends of two or more partial windings are electrically connected to each other so that there are two ends electrically connected to an external circuit including a resonance capacitor (not shown). For example, when winding 120 is configured such that one end of the first partial winding and one end of the second partial winding are electrically connected to each other, the other end of the first partial winding and the other end of the second partial winding become the ends of winding 120 (two ends electrically connected to an external circuit including a resonance capacitor not shown).

[0038] <Case 130> The case 130 is made of a non-metallic material, preferably an insulating material. The case 130 has an area where at least a portion of the core 110 is placed. The case 130 is preferably configured to ensure electrical insulation between the core 110 and the winding 120.

[0039] The case 130 may be made of, for example, a thermoplastic resin, a general-purpose plastic (for example, polyethylene (PE), polystyrene (PS), AS resin (AS or SAN), ABS resin (ABS), polypropylene (PP), polyvinyl chloride resin (PVC), methacrylic resin (PMMA), polyethylene terephthalate (PET)), a general-purpose engineering plastic (for example, polyamide (PA), polycarbonate (PC), polyacetal (POM), modified polyphenylene ether (m-PPE), polybutylene terephthalate (PBT)), a super engineering plastic (for example, polyphenylene sulfide (PPS), polysulfone (PSU), polyethersulfone (PES), polyaryl The case 130 may be made of any of the following materials: polyethylene terephthalate (PAR), polyamideimide (PAI), polyetheretherketone (PEEK), and liquid crystal polymer (LCP); thermosetting resins (e.g., phenolic resin (PF), urea resin (UF), melamine resin (MF), epoxy resin (EP), unsaturated polyester resin (UP), polyurethane (PU), diallyl phthalate resin (PDAP), silicone resin (SI), and alkyd resin polyphenylene sulfide (PPS)); or ceramics (e.g., zirconia (ZrO), alumina (AlO), silicon carbide (SiC), aluminum nitride (AlN), silicon nitride (SiN), boron nitride (BN), quartz glass (SiO), and Macol (fluorphlogopite)). Alternatively, the case 130 may be made of, for example, fluororesin, thermoplastic elastomer, polymethylpentene (PMP), biodegradable plastic, or cellulose-based plastic. Furthermore, the case 130 may be made of, for example, a mixture of two or more of the above materials.

[0040] In the example shown in Fig. 2, case 130 has hole 131. Fig. 2 illustrates a case where hole 131 is a through hole that penetrates in a direction parallel to the winding axis of winding 120 (y-axis direction). However, hole 131 may also be a bottomed hole that is open only on one side in the direction parallel to the winding axis of winding 120 (y-axis direction) and closed on the other side.

[0041] 2 illustrates a case where the shape of the cross section (xz cross section) of hole 131 in a direction perpendicular to the direction parallel to the winding axis of winding 120 (y-axis direction) is the same as the shape of the cross section (xz cross section) of core 110 in a direction perpendicular to the direction parallel to the winding axis of winding 120 (y-axis direction). Specifically, as shown in FIG. 2(b), a case where the shape of the cross section is rectangular is illustrated.

[0042] 2 illustrates a case where the size of the cross section (x-z cross section) of hole 131 in a direction perpendicular to the direction parallel to the winding axis of winding 120 (y-axis direction) is equal to or larger than the size of the cross section (x-z cross section) of core 110 in a direction perpendicular to the direction parallel to the winding axis of winding 120 (y-axis direction). Specifically, as shown in FIG. 2(b), the case is illustrated where the size of the cross section (x-z cross section) of hole 131 in a direction perpendicular to the direction parallel to the winding axis of winding 120 (y-axis direction) is approximately the same as (the same as or slightly larger than) the size of the cross section (x-z cross section) of core 110 in the direction perpendicular to the direction parallel to the winding axis of winding 120 (y-axis direction). However, the size of the cross section (xz cross section) of hole 131 in a direction perpendicular to the direction parallel to the winding axis of winding 120 (y-axis direction) may be larger than the size of the cross section (xz cross section) of core 110 in a direction perpendicular to the direction parallel to the winding axis of winding 120 (y-axis direction). In this case, an insulating material (for example, at least one of insulating paper and insulating tape) may be placed between the wall surface of hole 131 and the surface of core 110.

[0043] 2 illustrates a case in which the length of hole 131 in the direction parallel to the winding axis of winding 120 (y-axis direction) is approximately the same as (the same as or slightly shorter than) the length of core 110 in the direction parallel to the winding axis of winding 120 (y-axis direction). However, the length of hole 131 in the direction parallel to the winding axis of winding 120 (y-axis direction) may be longer or shorter than the length of core 110 in the direction parallel to the winding axis of winding 120 (y-axis direction). As shown in FIG. 2, when the length of hole 131 in the direction parallel to the winding axis of winding 120 (y-axis direction) is equal to or greater than the length of core 110 in the direction parallel to the winding axis of winding 120 (y-axis direction), it becomes possible to install the entire area of ​​core 110 inside case 130. On the other hand, if the length of hole 131 in the direction parallel to the winding axis of winding 120 (y-axis direction) is shorter than the length of core 110 in the direction parallel to the winding axis of winding 120 (y-axis direction), a portion of core 110 will be installed inside case 130.

[0044] In the example shown in FIGS. 1 and 2, the case 130 includes a winding portion 132, flange portions 133a to 133b, and lid portions 134a to 134b. 1 and 2 illustrate a case in which the winding portion 132 and the flange portions 133a to 133b are integrally molded (manufactured using the same mold). Therefore, there is no boundary line between the winding portion 132 and the flange portions 133a to 133b. Furthermore, the example illustrated in FIGS. 1 and 2 illustrates a case in which the lid portions 134a to 134b are manufactured using a mold different from that used for the winding portion 132 and the flange portions 133a to 133b. Therefore, there is a boundary line between the lid portions 134a to 134b and the flange portions 133a to 133b. The winding portion 132 and the flange portions 133a to 133b and the lid portions 134a to 134b may be manufactured using the same material or different materials.

[0045] As shown in Fig. 2, the aforementioned hole 131 is formed inside winding portion 132 and inside flange portions 133a-133b. Also, as shown in Figs. 1 and 2, winding portion 132 and flange portions 133a-133b are formed so that, in a cross section of case 130 in a direction perpendicular to a direction parallel to the winding axis of winding 120 (y-axis direction), flange portions 133a-133b have a shape that protrudes beyond winding portion 132. Fig. 2(a) illustrates a case where, in a cross section (y-z cross section) of case 130 in a direction parallel to the winding axis of winding 120 (y-axis direction) and parallel to the thickness direction of core 110 (z-axis direction), flange portions 133a-133b protrude beyond winding portion 132 on both the positive and negative sides of the z-axis, and the cross section has a substantially H-shape overall. Similarly, Figure 2(c) illustrates an example in which, in a cross section (xy cross section) of case 130 in the width direction (x-axis direction) of core 110 and in a direction parallel to the winding axis of winding 120 (y-axis direction), flange portions 133a to 133b protrude from winding portion 132 on both the positive and negative sides of the x-axis, and the cross section as a whole has a substantially H-shaped configuration.

[0046] 2 illustrates an example in which flanges 133a to 133b protrude more from winding portion 132 in the z-axis direction than in the x-axis direction. However, this is not necessarily the case. For example, flanges 133a to 133b may protrude more from winding portion 132 in the x-axis direction than in the z-axis direction. Furthermore, flanges 133a to 133b may protrude from winding portion 132 in the same manner in the x-axis direction and the z-axis direction (i.e., the regions of flanges 133a to 133b that protrude from winding portion 132 may have the same size and shape). Furthermore, flanges 133a to 133b may not be present (case 130 may have a shape that does not have a region that protrudes from winding portion 132).

[0047] Lids 134a and 134b are attached to the outer end surfaces of flanges 133a and 133b, respectively, in a direction parallel to the winding axis of winding 120 (y-axis direction). 2 illustrates an example in which the shape and size of lid portions 134a and 134b are the same as the shape and size of the outer end faces (the end faces on the negative side of the y-axis and the end faces on the positive side of the y-axis) of flange portions 133a and 133b in the direction parallel to the winding axis (y-axis direction) of winding 120. However, as long as lid portions 134a and 134b cover at least a portion (preferably the entirety) of hole 131, the shape and size of lid portions 134a and 134b are not particularly limited.

[0048] After core 110 is placed in hole 131, lid portions 134a and 134b are attached to the outer end surfaces of flange portions 133a and 133b, respectively, in a direction parallel to the winding axis of winding 120 (the y-axis direction). The method of attaching lid portions 134a to 134b is not particularly limited as long as they are attached so as not to fall off flange portions 133a to 133b. For example, flange portions 133a to 133b and lid portions 134a to 134b may be formed so that flange portions 133a to 133b and lid portions 134a to 134b fit together. In this case, lid portions 134a to 134b may be detachable from flange portions 133a to 133b, or may be non-detachable. Alternatively, lid portions 134a to 134b may be attached to flange portions 133a to 133b using an adhesive or the like.

[0049] 2 illustrates an example in which lid portions 134a and 134b are attached to both sides in the direction parallel to the winding axis of winding 120 (y-axis direction). However, a lid portion may be attached to only one side in the direction parallel to the winding axis of winding 120 (y-axis direction). For example, as described above, hole 131 may be a bottomed hole that is open only on one side in the direction parallel to the winding axis of winding 120 (y-axis direction) and closed on the other side. For example, if hole 131 is open only on the positive side of the y-axis and closed on the negative side of the y-axis, lid portion 134a may be attached to flange portion 133a, but lid portion 134b may not be attached to flange portion 133b (i.e., in this case, lid portion 134b is unnecessary). Furthermore, if the length of core 110 in a direction parallel to the winding axis of winding 120 (y-axis direction) is longer than the length of hole 131 in that direction and core 110 is installed so that it protrudes from case 130 on both sides in that direction, lids 134a-134b become unnecessary. In this case, it is preferable to fix core 110 to case 130 using, for example, an insulating adhesive. Note that even when lids 134a-134b are used, core 110 may be fixed to case 130 using an insulating adhesive.

[0050] 2 illustrates a case in which the winding 120 is wound around the winding portion 132, but not around the flange portions 133a and 133b. The winding 120 may be wound around the case 130 (winding portion 132) after the core 110 is placed inside the case 130 (hole 131), or the winding 120 may be wound around the case 130 (winding portion 132) after the core 110 is placed inside the case 130 (hole 131). If there is little (or no) clearance between the core 110 and the case 130 when the core 110 is placed inside the case 130, winding the winding 120 after placing the core 110 inside the case 130 may apply stress to the core 110, which may degrade the electrical characteristics (such as inductance L and quality factor Q) of the antenna coil 100. Therefore, in such a case, it is preferable to wind the winding 120 around the case 130 and then install the core 110 in (the hole 131 of) the case 130. However, for example, if the electrical characteristics required of the core 110 are low and the core 110 satisfies the desired electrical characteristics even if stress is applied to the core 110, or if the stress applied to the core 110 is small (for example, if a relatively thick insulating material is disposed between the wall surface of the hole 131 and the surface of the core 110), the core 110 may be installed in (the hole 131 of) the case 130 and then wind the winding 120 around the case 130.

[0051] The shape of the case is determined to match the shape of the core so as to have an area where at least a portion of the core is to be installed, and is not limited to the shape shown in Figures 1 and 2. For example, the case may include multiple case members that are combined with each other and have an area where at least a portion of the core is to be installed. For example, if the core has a shape that prevents the core from passing through the opening of the case, a second case member may be combined with the first case member with a portion of the core installed in the first case member. Furthermore, if the antenna coil 100 includes a case 130, the manufacturing process of the antenna coil 100, including winding the winding 120, insulating the metal material (e.g., metal wire) from the core 110, and positioning the core 110, is simplified, and the core 110 can be protected. However, the antenna coil 100 does not necessarily need to include the case 130. For example, the insulation of the core 110 may be ensured by at least one of immersing the core in resin, applying a surface coating by painting a non-insulating powder containing a powdered soft magnetic material, or forming an insulating material (e.g., at least one of oxide and nitride) on the surface of the core, such as anodizing or tufting. However, the insulation of the core 110 may not be ensured. Furthermore, the shape of the case 130 is not limited to the shape shown in FIGS. 1 and 2.

[0052] <Scope of application> The antenna coil 100 of this embodiment is not particularly limited in terms of the frequency it can use, as long as it is a coil for at least one of transmitting and receiving radio signals. For example, the frequency range for use of the antenna coil 100 of this embodiment is, for example, a frequency range of 1 kHz or more and 3 THz or less.

[0053] The antenna coil 100 of this embodiment may be applied to any device, as long as it is a coil for transmitting and / or receiving wireless signals. For example, the antenna coil 100 of this embodiment may be applied to equipment for specified low-power radio stations (e.g., devices for telemetry, telecontrol, and data transmission, remote controls for security devices, radio microphones, and wireless telephones (low-power, small, handheld devices)). The antenna coil 100 of this embodiment may also be applied to devices that transmit and receive radio waves via wireless LAN (Local Area Network) (Wi-Fi) or Bluetooth (registered trademark) (e.g., mobile phones, tablet devices, wireless peripheral devices for personal computers (e.g., mice, keyboards, styluses, printers), audio devices (e.g., headphones, speakers, FM transmitters), network devices (e.g., routers, access points), wearable devices (e.g., sports watches, smart glasses), game consoles, security cameras, radio-controlled vehicles (for operating small unmanned aerial vehicles such as drones), selfie sticks, etc.). The antenna coil 100 of this embodiment may also be applied to devices (beacons, radars) that transmit and receive radio waves in ships and aircraft. The antenna coil 100 of this embodiment may also be applied to devices that transmit and receive radio waves in automobiles (for example, devices that transmit and receive radio waves in smart entry (keyless entry), immobilizers, radars, TPMS (Tire Pressure Monitoring Systems), ETC (Electronic Toll Collection Systems), ETC (Electronic Toll Collection Systems), ITS (Intelligent Transport Systems), VICS (registered trademark) (Vehicle Information and Communication System), DSRC (Dedicated Short Range Communications), and DCM (Data Communication Module)).The antenna coil 100 of this embodiment may also be applied to other devices (DTV (Digital Terrestrial Television Broadcasting), GPS (Global Positioning System), mobile phones (6G / 5G / 4G / 3G lines, LTE (Long Term Evolution), etc.), mobile phone base station equipment, amateur radio station equipment), radio-controlled watches (watches, clocks) for receiving purposes, and radios.

[0054] It should be noted that the above-described embodiments of the present invention are merely examples of specific embodiments for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited by these. In other words, the present invention can be embodied in various forms without departing from its technical concept or main features. [Explanation of symbols]

[0055] 100 Antenna Coil 110 cores 120 windings 121a~121b Ends of windings 130 cases 131 Case Hole 132 Case winding section 133a~133b Case flange 134a~134b Case lid

Claims

1. An antenna coil for at least one of transmitting and receiving a radio signal, a core including a composite of multiple materials including a powdered soft magnetic material and a non-metallic material; a winding disposed in a wound state around the core; Equipped with An antenna coil, wherein the ratio of the volume of the powdered soft magnetic material to the volume of the core is 5 vol % or more and 95 vol % or less.

2. The core comprises a molded product having a plurality of types of materials including a powdered soft magnetic material and a non-metallic material; The antenna coil according to claim 1, wherein the density of the core, expressed by dividing the mass of the core by the volume of a region of a mold used to mold the multiple types of materials and into which the multiple types of materials are inserted, is 1 g / cm 3 or more and 9 g / cm 3 or less.

3. An antenna coil for at least one of transmitting and receiving a radio signal, a core including a composite of multiple materials including a powdered soft magnetic material and a non-metallic material; a winding disposed in a wound state around the core; Equipped with the core is a molded product having a plurality of types of materials including a powdered soft magnetic material and a non-metallic material; An antenna coil, wherein the density of the core, expressed by dividing the mass of the core by the volume of a region of a mold used to mold the multiple types of materials and into which the multiple types of materials are inserted, is 1 g / cm 3 or more and 9 g / cm 3 or less.

4. The powdered soft magnetic material includes at least one of a powdered Fe-based amorphous alloy material, a powdered Fe-based nanocrystalline alloy material, a powdered pure iron, a powdered ferrite, a powdered permalloy, and a powdered silicon steel material. The antenna coil according to any one of claims 1 to 3.

5. The antenna coil according to claim 1 , wherein the non-metallic material includes a resin.

6. The antenna coil according to any one of claims 1 to 5, further comprising a case having an area in which at least a portion of the core is placed, the case including a non-metallic material.

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