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 plurality of soft magnetic material plates arranged so as to be mutually stacked and each having a saturation magnetic flux density equal to or more than 500 mT; 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 thinner. Typically, improving the performance of an antenna coil involves increasing the inductance L and quality factor Q. L and Q are determined by the magnetic material used for the core, and for the same inductance L and quality factor Q, the higher the saturation magnetic flux density of the core, the more compact (thinner) the antenna coil (core and windings) can be. However, the saturation magnetic flux density of ferrite is limited to approximately 500 mT, making it difficult to miniaturize the antenna coil while maintaining the inductance L and quality factor Q.

[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 is an antenna coil for at least one of transmitting and receiving a radio signal, and comprises: a core having a plurality of soft magnetic plates arranged in a stacked state, each having a saturation magnetic flux density of 500 mT or more; a case including a region where at least a portion of the core is disposed, the case including a non-metallic material; and a winding disposed in a wound state around the case. the case has a hole, and at least a portion of the core is inside the hole, the hole having at least one of a winding axis direction opening and an outer circumferential surface opening, the winding axis direction opening being an opening that is present in at least one of both end faces of the case in a direction parallel to the winding axis of the winding, and having a size equal to or larger than the area of ​​the end face of the core in the direction parallel to the winding axis that is inside the hole, and the outer circumferential surface opening being an opening that is present in a surface of the case that faces the winding, and having a size equal to or larger than the area of ​​the end face of the core in a direction parallel to the depth direction of the hole. [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. [Figure 3] FIG. 10 is a diagram showing an example of the relationship between the core thickness and the quality factor Q. 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 bird's-eye view of the antenna coil 100. 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 of Fig. 2(a), and Fig. 2(c) is a cross-sectional view taken along line II of Fig. 2(b).

[0011] 1 and 2, 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. 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 multiple soft magnetic plates arranged in a stacked (laminated) state, each having a saturation magnetic flux density of 500 mT or more. FIGS. 1 and 2 illustrate a case in which the shape of the plate surface of the soft magnetic plate is rectangular. However, the shape of the plate surface of the soft magnetic plate is not limited to a rectangle and may be, for example, a square, a cylindrical, or other shape. Furthermore, the soft magnetic plates may be stacked (laminated) in a separate state without facing each other by using a case or coating. In other words, stacking (laminarizing) is not limited to facing the plate surfaces of the soft magnetic plates. For convenience of illustration, the number of soft magnetic plates shown in FIGS. 1 and 2 is less than the actual number.

[0013] FIG. 3 is a diagram showing an example of the relationship between the thickness t of the soft magnetic plate and the quality factor Q. In FIG. The inventors compared the characteristics of a core made by laminating multiple soft magnetic plates with a ferrite core. Here, the inductance L at a frequency of 40 kHz was 2.9 mH, the quality factor Q at a frequency of 40 kHz was 39.8, the length was 50 mm, and the cross-sectional area was 25 mm. 2 and the volume is 1250mm 3 The following example shows a comparison with a ferrite core with a weight of 6.1 g.

[0014] Here, the term "length" refers to the length in the direction parallel to the winding axis of the winding (the direction parallel to the central axis (center line) of the antenna coil; in the example shown in Figures 1 and 2, it is the length in the direction parallel to the y-axis). Multiple Fe-based amorphous alloy ribbons, multiple Fe-based nanocrystalline alloy ribbons, and multiple silicon steel sheets were each fabricated with the same length (50 mm) and width as the ferrite core. Then, cores were fabricated by laminating multiple Fe-based amorphous alloy ribbons, multiple Fe-based nanocrystalline alloy ribbons, and multiple silicon steel sheets, each with a different thickness (number of laminated sheets). An antenna coil was fabricated by winding a winding around each of the cores fabricated in this way so that the inductance L at a frequency of 40 kHz was the same as the inductance L of the ferrite core (= 2.9 mH). The quality factor Q of each antenna coil was then measured. The inductance L and quality factor Q were measured using an "Impedance Analyzer IM3570" manufactured by Hioki E.E. Corporation.

[0015] In FIG. 3, graph 301 shows the reference quality factor Q. As described above, the thickness of the ferrite core to be compared with the core formed by laminating multiple soft magnetic plates is 5 mm. The quality factor Q of an antenna coil using this 5 mm thick ferrite core is shown in graph 301 as the reference quality factor Q. Graph 302 shows the quality factor Q of an antenna coil using a core formed by laminating multiple Fe-based nanocrystalline alloy ribbons. Graph 303 shows the quality factor Q of an antenna coil using a core formed by laminating multiple Fe-based amorphous alloy ribbons. Graph 304 shows the quality factor Q of an antenna coil using a core formed by laminating multiple silicon steel plates.

[0016] As shown in Figure 3, the quality factor Q increases in the following order for all thicknesses: Fe-based nanocrystalline alloy ribbon, Fe-based amorphous alloy ribbon, and silicon steel plate. In particular, the quality factor Q of an antenna coil using a core laminated with multiple Fe-based nanocrystalline alloy ribbons significantly exceeds the reference quality factor Q (Graph 301) even when the thickness is thin (e.g., 0.5 mm). The weight of a core laminated with multiple Fe-based nanocrystalline alloy ribbons to a thickness of 0.5 mm is 0.9 g. Meanwhile, as mentioned above, the weight of the comparative ferrite core is 6.1 g. Therefore, by using a core laminated with multiple Fe-based nanocrystalline alloy ribbons, the weight of the core can be significantly reduced to one-sixth of that of the comparative ferrite core. An antenna coil using this core can be half the weight of an antenna coil using a ferrite core for the same volume.

[0017] Furthermore, by laminating multiple Fe-based amorphous alloy ribbons, multiple Fe-based nanocrystalline alloy ribbons, and multiple silicon steel sheets, a thinner core than a ferrite core can be realized. Fe-based amorphous alloy ribbons, Fe-based nanocrystalline alloy ribbons, and silicon steel sheets have higher Curie temperatures than ferrite. Therefore, using Fe-based amorphous alloy ribbons, Fe-based nanocrystalline alloy ribbons, and silicon steel sheets as soft magnetic plates can suppress decreases in inductance and quality factor Q, even in high-temperature environments. Furthermore, Fe-based amorphous alloy ribbons, Fe-based nanocrystalline alloy ribbons, and silicon steel sheets have saturation magnetic flux densities more than twice as high as ferrite. Therefore, using Fe-based amorphous alloy ribbons, Fe-based nanocrystalline alloy ribbons, and silicon steel sheets as soft magnetic plates can reduce the core volume by more than half while maintaining inductance and quality factor Q. Furthermore, by using a winding method suitable for the miniaturized core, the antenna volume can be reduced. For example, by winding the wire tightly around a miniaturized core or by winding the wire around the miniaturized core in a case dedicated to the core, the volume after winding can be reduced, thereby making it possible to miniaturize the antenna coil 100. Furthermore, Fe-based amorphous alloy ribbons and Fe-based nanocrystalline alloy ribbons have higher saturation magnetic flux densities than silicon steel sheets. Therefore, by using Fe-based amorphous alloy ribbons and Fe-based nanocrystalline alloy ribbons, the antenna coil 100 can be made even smaller.

[0018] For the above reasons, the soft magnetic plate may be any plate-shaped material made of a soft magnetic material, but preferably includes at least one of an Fe-based amorphous alloy ribbon and an Fe-based nanocrystalline alloy ribbon. Furthermore, when facilitating the manufacture of the core 110 is important, the soft magnetic plate preferably includes only one of an Fe-based amorphous alloy ribbon and an Fe-based nanocrystalline alloy ribbon. Furthermore, when increasing the quality factor Q of the antenna coil is important, the soft magnetic plate preferably includes only an Fe-based nanocrystalline alloy ribbon. However, the soft magnetic plate may include both an Fe-based amorphous alloy ribbon and an Fe-based nanocrystalline alloy ribbon. For example, when a core is to be lighter in weight than a ferrite core and to have characteristics that utilize the advantages of both an Fe-based amorphous alloy ribbon and an Fe-based nanocrystalline alloy ribbon, the soft magnetic plate may include both an Fe-based amorphous alloy ribbon and an Fe-based nanocrystalline alloy ribbon.

[0019] The composition of the starting material for the Fe-based nanocrystalline alloy ribbon may be determined depending on the properties required for the Fe-based nanocrystalline alloy ribbon. The following composition formulas are exemplified: 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.

[0020] 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.

[0021] When bccFe crystals are generated in an Fe-based nanocrystalline alloy ribbon manufactured by subjecting the above starting materials to heat treatment or the like, the crystal size of αFe is preferably 1 nm or more and 1000 nm or less. The crystal size of αFe 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, for example, a value calculated from the half-width of the peak of a diffraction line obtained by X-ray diffraction. Furthermore, even if an amorphous Fe-based nanocrystalline alloy ribbon in which bccFe crystals are not generated is formed without heat treatment of the starting material, high magnetic permeability can be obtained as the core. Therefore, although heat treatment of the starting material is preferable, it is not necessary to heat treat the starting material. By not subjecting the starting material to heat treatment, an amorphous Fe-based nanocrystalline alloy ribbon containing no bccFe crystals can be obtained, which prevents the Fe-based nanocrystalline alloy ribbon from becoming brittle. Therefore, the mechanical strength of the core 110 can be improved. Furthermore, in order to improve the magnetic properties of the core, 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.

[0022] The composition of the starting material for the Fe-based amorphous alloy ribbon may be determined depending on the properties required for the Fe-based amorphous alloy ribbon. The following composition formulas are exemplified: 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.

[0023] 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.

[0024] When bccFe crystals are generated in an Fe-based amorphous alloy ribbon 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 ribbon 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, by performing stress relief annealing on the core for various applications, the required magnetic permeability of the core 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 essentially preferred, heat treatment on the starting material is not necessarily required. By not performing heat treatment on the starting material, an Fe-based amorphous alloy ribbon containing no bccFe crystals can be obtained, which can prevent the Fe-based amorphous alloy ribbon from becoming brittle. This can improve the mechanical strength of the core 110. Furthermore, a magnetic field may be applied to the starting material during the heat treatment process to improve the magnetic properties of the core, but it is not necessary to apply a magnetic field to the starting material during the heat treatment process.

[0025] In the following description, the Fe-based nanocrystalline alloy ribbon and / or the Fe-based amorphous alloy ribbon will be referred to as ribbon as necessary. When the core 110 is formed using a ribbon, the thickness of the ribbon is preferably in the range of 5 μm to 35 μm. When the cross section of the core 110 is rectangular, the thickness of the core 110 (the length in the stacking direction of the ribbon) is preferably in the range of 10 μm to 300 mm. The length of the core 110 (the length in the direction parallel to the winding axis of the winding 120) is preferably in the range of 1 mm to 300 mm. The width of the core 110 (the length in the direction perpendicular to the stacking direction of the ribbon and the direction parallel to the winding axis of the winding 120) is preferably in the range of 1 mm to 300 mm.

[0026] Next, an example of a method for manufacturing the core 110 will be described. The method for producing the soft magnetic plate is not particularly limited, and the soft magnetic plate may be produced by a known method (for example, a liquid quenching method, a spinning method in a rotating liquid, or a sputtering method).

[0027] The soft magnetic material plate, e.g., a ribbon, manufactured as described above is cut into a predetermined shape. The method for cutting the ribbon is not particularly limited. The ribbon can be cut by a known method (e.g., slitting). However, cutting the ribbon into strips with metal scissors or the like may cause warping or twisting of the ribbon. Stacking multiple steel ribbons in this warped or twisted state may result in stress being applied to the ribbons. This may result in degradation of the electrical characteristics (inductance L, quality factor Q, etc.) of the antenna coil 100. Therefore, it is preferable to reduce warping and twisting of the ribbon by appropriately adjusting the clearance between the upper and lower blades of the metal scissors or the like. From this perspective, it is preferable that the flatness of the ribbon, as specified in JIS B 0621:1984, is 10 mm or less.

[0028] The plurality of ribbons cut as described above are stacked (laminated) so that their plate surfaces face each other. At this time, it is preferable to avoid contact with the ribbons and ensure insulation in order to increase the quality factor Q. For example, if insulation between the ribbons is ensured by forming an insulating material (e.g., at least one of oxides such as oxide films, nitrides, and resins) on the ribbon surfaces, it is possible to sandwich a resin or adhesive (e.g., at least one of thermoplastic resins, thermosetting resins, photocurable resins, rubber / elastomers, silicon-based adhesives, and calcium-based adhesives) between the ribbons, eliminating the need to bond the ribbons to each other. It is also preferable to fix both ends (ends in the y-axis and / or z-axis directions) of the stacked ribbons, but they may be stacked separately without fixing them. Alternatively or in addition to this, it is preferable to insulate the stacked ribbons from other conductors to prevent electrical conduction between them and metal materials (e.g., metal wires) in order to increase the inductance and quality factor Q. For example, the stacked thin strips may be immersed in resin (e.g., at least one of thermoplastic resin, thermosetting resin (infrared curing), and photocurable resin (ultraviolet curing)) or the stacked thin strips may be coated with powder coating, so long as insulation between the stacked thin strips and the metal material is maintained, and case 130 may not be used.

[0029] 1 and 2, the example illustrates a case in which the ribbon is stacked in the x-axis direction (a direction parallel to the winding axis of the winding 120 (y-axis direction) and a direction perpendicular to the depth direction of the hole 131 (z-axis direction)). However, the ribbon is not limited to the x-axis direction. For example, the ribbon may be stacked in the z-axis direction. As will be described in detail later, the hole 131 is formed in the case 130, and the core 110 is placed in the hole 131.

[0030] <Winding 120> The winding 120 is arranged in a wound state around the core 110 (surrounding the core 110). The winding 120 is realized by a known technique, for example, 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 of the antenna coil 100) is parallel to the y-axis. Note that for convenience of illustration, the number of turns of the winding 120 is shown in FIGS. 1 and 2 as being fewer than the actual number of turns. Ends 121a and 121b of the winding 120 are electrically connected to an external circuit including a resonance capacitor (not shown).

[0031] <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.

[0032] 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.

[0033] In the example shown in FIGS. 1 and 2, the case 130 has a hole 131 extending in a direction parallel to the winding axis of the winding 120 (the y-axis direction). The hole 131 is a bottomed hole. The bottom of the hole 131 refers to the surface seen from the front when looking down at the hole 131 in a direction perpendicular to the winding axis of the winding 120 (the central axis of the antenna coil 100) (in the example shown in FIGS. 1 and 2, the negative z-axis direction) with nothing installed in the hole 131. At least a portion of the core 110 is installed in the hole 131. FIGS. 1 and 2 illustrate a case in which the entire core 110 is installed in the hole 131. This arrangement more reliably protects the core 110 and prevents the core 110 from coming into contact with components other than the case 130 (e.g., the winding 120). However, this is not necessarily required. For example, end faces 111a to 111b of core 110 in a direction parallel to the winding axis of winding 120 (y-axis direction) may protrude from hole 131 (may be outside case ).

[0034] Furthermore, hole 131 in this embodiment has at least one of openings 131a to 131b on the winding axis direction side and opening 131c on the outer circumferential surface side. 1 and 2 illustrate a case in which winding axis direction-side openings 131a-131b are formed on at least one of end faces 132a-132b of case 130 in the direction parallel to the winding axis of winding 120 (y-axis direction). The example shown in FIGS. 1 and 2 illustrates a case in which winding axis direction-side openings 131a-131b are formed on both end faces 132a-132b of case 130 in the direction parallel to the winding axis of winding 120 (y-axis direction). Winding axis direction-side openings 131a-131b are larger than the area of ​​end faces 111a-111b of core 110 in the direction parallel to the winding axis of winding 120 (y-axis direction) that is present inside hole 131.

[0035] The outer peripheral surface opening 131c is formed on an outer peripheral surface 133 of the case 130, which is the surface of the case 130 that faces the winding 120. As shown in FIG. 1, the outer peripheral surface 133 of the case 130 is the surface of the case 130 that is located between the end surfaces 132a and 132b of the case 130. The example shown in FIGS. 1 and 2 illustrates a case in which the winding 120 is wound such that the innermost region of the winding 120 (the region closest to the central axis of the antenna coil 100) faces the outer peripheral surface 133 of the case 130. Note that an insulating material (e.g., at least one of insulating paper and insulating tape) may be placed between the winding 120 and the outer peripheral surface 133 of the case 130. The outer peripheral surface opening 131c is larger than the region of the end surface 111c of the core 110 that is located inside the hole 131 in the direction parallel to the depth direction of the hole 131 (the z-axis direction).

[0036] 1 and 2 show an example in which case 130 has both winding axis direction side openings 131a-131b and outer circumferential surface side opening 131c, which makes it easier to install core 110 in case 130.

[0037] If the clearance between the core 110 and the case 130 is small (or nonexistent) when the core 110 is placed inside the case 130, winding the winding 120 therearound may cause stress on the core 110, resulting in a deterioration in the electrical characteristics (such as inductance L and quality factor Q) of the antenna coil 100. Therefore, it is preferable to wind the winding 120 around the case 130 before placing the core 110 in the case 130 (hole 131). By forming the winding axis direction openings 131a-131b as described above, it is possible to wind the winding 120 around the case 130 before placing the core 110 in the case 130 (hole 131). Therefore, it is preferable that the case 130 have the winding axis direction openings 131a-131b. However, for example, if the electrical characteristics required of core 110 are low and core 110 satisfies the desired electrical characteristics even if stress is applied to core 110, or if the stress applied to core 110 is small (for example, if a relatively thick insulating material is placed between winding 120 and outer surface 133 of case 130), core 110 may be placed in case 130 (hole 131) and then winding winding 120 around case 130.

[0038] Incidentally, if the antenna coil 100 includes a case 130, the manufacturing process of the antenna coil 100, such as winding the winding 120 and positioning the core 110, is facilitated, and the core 110 can be protected, which is preferable. However, the antenna coil 100 does not necessarily need to include a case 130. In this case, as described above, the stacked thin ribbons can be fixed by, for example, sandwiching a resin between the thin ribbons to bond them to each other, or by coating the periphery of the stacked thin ribbons with a resin to bond them together. Furthermore, the shape of the case 130 is not limited to the shape shown in FIGS. 1 and 2. If the stacked thin ribbons can be fixed using the case 130, the above-described bonding of the thin ribbons with a resin or the like may or may not be performed.

[0039] <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 100 MHz or less.

[0040] Furthermore, 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 radio signals, but may be applied to devices that transmit and receive radio waves on ships, radio-controlled clocks, radios, and devices that transmit and receive radio waves in smart entries (keyless entries), for example.

[0041] 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]

[0042] 100 Antenna Coil 110 cores 111a~111c Core end faces 120 windings 121a~121b Ends of windings 130 cases 131 Case Hole 132a~132b Case end face 131a-131b Openings on the winding axis side of the case 131c Case outer surface opening 133 Case outer surface 301 Graph showing the standard quality factor Q 302 Graph showing the quality factor Q of an antenna coil using a core made of laminated Fe-based nanocrystalline alloy ribbons 303 Graph showing the quality factor Q of an antenna coil using a core made of laminated Fe-based amorphous alloy ribbons 304 Graph showing the quality factor Q of an antenna coil using a core made of laminated silicon steel plates

Claims

1. An antenna coil for at least one of transmitting and receiving a radio signal, a core including a plurality of soft magnetic plates arranged in a stacked state, each having a saturation magnetic flux density of 500 mT or more; a case including a region in which at least a portion of the core is disposed, the case including a non-metallic material; a winding disposed in a wound state around the case; Equipped with the case has a hole; At least a portion of the core is present inside the hole, the hole has at least one of an opening on the winding axis direction side and an opening on the outer circumferential surface side, the winding axis direction opening is an opening that is present in at least one of both end faces of the case in a direction parallel to the winding axis of the winding, and that has a size that is equal to or larger than a size of a region that is present inside the hole, within a region of the end face of the core in the direction parallel to the winding axis of the winding, An antenna coil, wherein the outer surface opening is an opening that exists on the surface of the case facing the winding, and has a size that is greater than or equal to the size of the area of ​​the end surface of the core that exists inside the hole in a direction parallel to the depth direction of the hole.

2. The antenna coil according to claim 1 , wherein the soft magnetic plate includes at least one of an Fe-based amorphous alloy ribbon and an Fe-based nanocrystalline alloy ribbon.

3. The antenna coil according to claim 1 , wherein the hole is a blind hole.

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