JP2004166071A - Magnetic core for antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic core for antenna which does not cause deviation in the width direction of a soft magnetic thin belt material, is light and compact, has constant strength in a longitudinal direction, has no irregularity in the curved surface and thickness of the soft magnetic thin body material at a lengthwise end part in each product and obtains optional curved surface and thickness as designed. <P>SOLUTION: In an antenna comprising the magnetic core 1 for an antenna where belt-like cobalt based amorphous 2 (soft magnetic thin belt material) is wound around a bobbin 3 to be laminated and which has a curved surface 4 at end parts, a coil 5 for transmission wound around the magnetic core 1 for antenna, and an oscillation circuit 6 connected to the coil 5, the bobbin 3 is provided with recessed parts 7 for winding around the cobalt based amorphous 2 a plurality of times, and the cross section shape of the recessed parts 7 of the bobbin 3 in the width direction is of an H shape 9, providing a tapered shape 11 with a plane surface 12 at an end part 10. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an antenna used for mobile communication such as a transceiver and a mobile phone, and more particularly to an antenna core having a concave portion for winding a soft magnetic ribbon material around a bobbin of the antenna core.
[0002]
[Prior art]
The antenna core 21 of the conventional antenna 20 of FIG. 11 relating to the present invention has a nanocrystalline magnetic alloy ribbon 22 laminated thereon (for example, see Patent Document 1). The conventional antenna 20 is configured by winding a signal transmission coil 24 connected to a transmitter 23 around an antenna core 21. The antenna core 21 is mainly made of a laminate of a nanocrystalline magnetic alloy ribbon 22 as a high-permeability magnetic material. However, the conventional antenna magnetic core 21 of FIG. 11 is a quadrangular prism, and the end of the antenna magnetic core 21 has a flat surface 25 and a rectangular shape. When the end of the antenna core 21 is rectangular in the plane 25, a magnetic field having high directivity is formed in the longitudinal direction of the antenna core 21 and a high electric field strength is obtained. There is a problem that the electric field strength in the orthogonal direction is reduced. In addition, in order to form the antenna core 21 into a quadrangular prism, a process such as cutting and polishing of the end portion after laminating the nanocrystalline magnetic alloy ribbons 22 is required, which takes a lot of man-hours and increases the cost. .
[0003]
To solve this problem, in the prior application of FIG. 12 (Japanese Patent Application No. 2002-309908), the inventor of the present application has invented an antenna magnetic core 32 in which a soft magnetic ribbon material 31 is wound and laminated as a result of earnest research. An antenna 30 shown in FIG. 12 includes an antenna magnetic core 32 having a curved surface 34 having a radius of curvature R at an end portion, and a band-shaped Co-based amorphous material 31 (soft magnetic thin material) wound around a bobbin 33 and laminated. , And an oscillation circuit 36 connected to the coil 35. Since the magnetic field is generated in the direction normal to the curved surface 34, the formation of the curved surface 34 improves the electric field strength Hy in the Y direction, which is a direction orthogonal to the longitudinal direction of the antenna core. Therefore, the electric field strength Hy in the direction orthogonal to the longitudinal direction of the antenna core 32 is high, and a stable reception level can be obtained even when the antenna core 32 is rotated, so that the antenna 30 with high productivity can be provided.
[0004]
[Patent Document 1]
JP-A-07-278763 (FIG. 1)
[0005]
[Patent Document 2]
JP-A-07-221533 (pages 3-4, FIGS. 1, 3)
[0006]
[Problems to be solved by the invention]
However, in the conventional antenna magnetic core 32, when the soft magnetic ribbon material 31 is wound around the bobbin 33 a plurality of times, a deviation occurs in the width direction of the soft magnetic ribbon material 31. Further, since the antenna core 32 is used for transmission and reception in mobile communication such as a transceiver and a mobile phone, it is required to be lightweight and compact. However, when the bobbin 33 is made lightweight and compact, the strength of the antenna magnetic core 32 in the longitudinal direction is insufficient and the bobbin 33 is deformed, and the soft magnetic ribbon material 31 wound and fixed once on the bobbin 33 is loosened and shifted. Further, if the soft magnetic ribbon material 31 is deformed or displaced, there is a problem that the transmission / reception performance varies from product to product and a stable high transmission / reception level cannot be obtained.
[0007]
According to the present invention, when the soft magnetic ribbon material 31 is wound around the bobbin 33, the soft magnetic ribbon material 31 does not shift in the width direction, and is lightweight, compact, and fixed in the longitudinal direction of the antenna core 32. And the curved surface 34 of the soft magnetic ribbon material 31 at the longitudinal end of the antenna core 32 has no variation for each product, and an arbitrary designed curved surface and thickness can be obtained. The task is to
[0008]
[Means for Solving the Problems]
The invention according to claim 1 for solving the above-mentioned problem is characterized in that in a magnetic core for an antenna comprising a band-shaped soft magnetic ribbon material and a bobbin for winding the soft magnetic ribbon material a plurality of times, The bobbin includes a concave portion for winding the soft magnetic ribbon material a plurality of times. "
[0009]
According to the first aspect of the present invention, when the soft magnetic ribbon material is wound around the bobbin, the concave portion acts as a guide to provide the soft magnetic ribbon material. The displacement of the ribbon material in the width direction can be prevented.
[0010]
The invention according to claim 2 for solving the above problem is characterized in that "the cross-sectional shape of the bobbin in the width direction of the concave portion is an H-shape".
[0011]
According to the second aspect of the present invention, since the cross-sectional shape of the concave portion of the bobbin in the width direction is H-shaped, the strength of the antenna core in the longitudinal direction is improved. Since the antenna core is used for transmission and reception in mobile communication such as a transceiver and a mobile phone, it is required to be lightweight and compact. However, if the bobbin is made lightweight and compact, it may be deformed due to insufficient strength in the longitudinal direction. By making the cross-sectional shape in the width direction of the concave portion of the bobbin H-shaped, it is possible to improve the strength in the longitudinal direction while also having a function of a guide when winding the soft magnetic ribbon material. Further, it is possible to prevent the soft magnetic ribbon material wound and fixed once on the bobbin from being loosened or displaced. Therefore, it is possible to solve the problem of variations in transmission / reception performance for each product due to the deformation or displacement of the soft magnetic ribbon material, and the problem that a stable high transmission / reception level cannot be obtained.
[0012]
The invention according to claim 3 for solving the above-mentioned problem is characterized in that “the bobbin is a resin molded product”.
[0013]
According to the third aspect of the invention, since the bobbin is formed of a resin molded product, it is possible to reduce the weight of the bobbin and easily form the bobbin into a commissioned shape. Insufficient strength in the longitudinal direction due to resinification can be compensated for by the H-shaped configuration of the second aspect.
[0014]
The invention according to claim 4 for solving the above-mentioned problem is characterized in that “the cross-sectional shape in the longitudinal direction of the end of the concave portion of the bobbin is a tapered shape having a surface at the end”.
[0015]
According to the fourth aspect of the present invention, since the longitudinal cross-sectional shape of the end of the concave portion of the bobbin is a tapered shape having a surface at the end, even if the soft magnetic ribbon material is wound around the bobbin a plurality of times, the magnetic core for the antenna can be obtained. An arbitrary curved surface or thickness can be obtained at the end of the. Therefore, it is possible to prevent variations in transmission / reception performance of the antenna core. Further, even if a large force is applied to the end of the soft magnetic ribbon material from the outside, the longitudinal cross-sectional shape of the end of the concave portion of the bobbin is a tapered shape having a surface at the end. Problems such as bending and cutting can be solved.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the antenna magnetic core 1 of the present invention will be described in detail with reference to the drawings.
[0017]
(1st Embodiment)
FIG. 1 shows the configuration of an antenna using the antenna magnetic core 1 of the present invention. A band-shaped Co-based amorphous material 2 (soft magnetic ribbon material) is wound around a bobbin 3 and laminated, and an antenna core 1 having a curved surface 4 at an end portion, and a transmission coil 5 wound around the antenna core 1 And an oscillation circuit 6 connected to the coil 5.
[0018]
In the present embodiment, a band-shaped Co-based amorphous material 2 having a width of 4 mm and a thickness of 20 μm is wound 20 times with a tension of 500 g. In addition to the Co-based amorphous material 2, soft magnetic ribbon materials such as amorphous alloys and nanocrystalline magnetic alloys having high magnetic permeability and low coercive force can be used.
[0019]
FIG. 2 shows the bobbin 3 constituting the antenna magnetic core 1 according to the first embodiment of the present invention before the Co-based amorphous 2 is wound. The bobbin 3 is formed by processing a glass fiber reinforced resin material (for example, PPS, liquid crystal polymer, or the like), and includes a concave portion 7 for winding the Co-based amorphous material 2. The height when the Co-based amorphous material 2 is wound is substantially the same as the height of the thick portions 8 on both sides of the concave portion 7.
[0020]
FIG. 3 is an enlarged cross-sectional view taken along line AA of the bobbin 3 of FIG. 2 according to the first embodiment. Both sides of the bobbin 3 are provided with concave portions 7, and thick portions 8 are formed on both sides of the concave portions 7 to form an H-shaped shape 9. The thick portion 8 extends in the longitudinal direction of the bobbin 3 and functions to guide the Co-based amorphous material 2 while suppressing deformation in the longitudinal direction of the bobbin 3 which is a resin molded product.
[0021]
FIG. 4 is an enlarged cross-sectional view of the bobbin 3 of FIG. 2 according to the first embodiment taken along line BB, showing a state where the Co-based amorphous material 2 is wound. The cross section BB is obtained by cutting the end 10 of the concave portion 7 of the bobbin 3 in the longitudinal direction, and has a tapered shape 11 having a flat surface 12 at the end 10.
[0022]
FIG. 5 shows a rectangular cross section taken along the line BB. However, if the Co-based amorphous material 2 is wound around the bobbin 3 a plurality of times, the outermost diameter curved surface 4 swells and the thickness increases. This is considered to be due to the fact that the Co-based amorphous 2 has a certain tension. If the outermost curved surface 4 swells or increases in thickness, the transmission / reception performance of the antenna core 1 varies from product to product.
[0023]
A bobbin 3 having a tapered shape 11 having a flat surface 12 at an end portion 10 according to the first embodiment of the present invention shown in FIG. 4 and a Co-based amorphous material 2 in a case where the BB cross-sectional shape shown in FIG. The influence of the later thickness and the inductance L which is an electrical characteristic of the magnetic core 1 for an antenna was measured. At this time, the thickness of the recess 7 of the bobbin 3 is 1 mm, the length of the recess 7 of the bobbin 3 in the longitudinal direction is 60 mm, the width of the Co-based amorphous 2 is 4 mm, and the tension when winding the Co-based amorphous 2 is set. Was 500 g. The thickness of the plane 12 in FIG. 4 was 0.3 mm.
[0024]
In the case of the bobbin 3 having the tapered shape 11 having the flat surface 12 at the end 10 according to the first embodiment of FIG. 4, the thickness of the Co-based amorphous 2 after winding is 5 mm from the end 10 mm. 5) is 1.6 mm and the thickness near the center of the bobbin 3 is 1.7 mm, whereas in the case of the square shape in FIG. 5, the thickness at the end is 2.4 mm and the bobbin 3 The thickness near the center was 2.4 mm. The difference in thickness at the end was 0.8 mm (bulge).
[0025]
Regarding the characteristic of the inductance L, which is an electrical characteristic, the wire diameter of the coil 5 wound around the magnetic core 1 for an antenna is 0.24 mm, the number of turns is 55, and the value of the inductance L when formed in a single-layer winding is shown. And an impedance analyzer. In the case of the tapered shape 11 having the flat surface 12 at the end 10 which is the first embodiment of FIG. 4, the value of the inductance L is 134 μH, whereas in the case of the square shape of FIG. Was 137 μH. The swelling of the Co-based amorphous material 2 after winding caused a difference (variation) in inductance L of 3 μH.
[0026]
FIG. 6 shows a triangular BB cross section. However, if the Co-based amorphous material 2 is wound around the bobbin 3 a plurality of times, the curved surface 4 having the outermost diameter is bent. When the outermost diameter curved surface 4 is bent, the transmission / reception performance of the antenna core 1 varies from product to product. Further, when a large force acts on the acute angle portion of the triangular tip from the outside, the Co-based amorphous 2 wound on the bobbin 3 may be cut.
[0027]
In the first embodiment of the present invention, since the concave portion 7 for winding the Co-based amorphous material 2 a plurality of times is provided, the concave portion 7 functions as a guide when the Co-based amorphous material 2 is wound around the bobbin 3. And Co-based amorphous 2 can be prevented from shifting in the width direction.
[0028]
In addition, by forming the cross-sectional shape of the concave portion 7 of the bobbin 3 in the width direction as the H-shaped shape 9, it is possible to improve the strength in the longitudinal direction while also having the function of a guide when winding the Co-based amorphous material 2. become. Further, it is possible to prevent the Co-based amorphous material 2 wound and fixed once on the bobbin 3 from being loosened or shifted. Therefore, it is possible to solve the problem of variation in transmission / reception performance of each product due to deformation, loosening, and displacement of the Co-based amorphous material 2, and the problem that a stable high transmission / reception level cannot be obtained.
[0029]
Further, by forming the bobbin 3 as a resin molded product of glass fiber reinforced PPS, it is possible to easily reduce the weight of the bobbin 3 and to form the bobbin 3 into a commissioned shape. Insufficient strength in the longitudinal direction of the bobbin 3 due to resinification can be solved by making the cross section of the recess 7 in the width direction an H-shaped shape 9.
[0030]
Further, by forming the cross-sectional shape in the longitudinal direction of the end portion 10 of the concave portion 7 of the bobbin 3 into a tapered shape 11 (FIG. 4) having a flat surface 12 at the end portion 10, the Co-based amorphous material 2 is wound around the bobbin 3 a plurality of times. However, since the curved surface 4 having an arbitrary thickness is formed at the end of the antenna core 1, it is possible to prevent variations in the transmission and reception performance of the antenna core 1. Further, even if a large force acts on the end of the Co-based amorphous material 2 from the outside, the longitudinal cross-sectional shape of the end 10 of the concave portion 7 of the bobbin 3 is a tapered shape 11 having a flat surface 12 at the end 10. , Co-based amorphous 2 can be solved.
[0031]
(2nd Embodiment)
FIG. 7 shows a second embodiment of the present invention, which is different from a tapered shape 11 having a flat surface 12 at an end portion 10 in FIG. 4 in that a tapered shape 11a having a curved surface 13 at the end portion 10 is provided. Other parts are the same as those in FIG. 4, and the same parts and shapes will be described using the same reference numerals.
[0032]
In the tapered shape 11a having the curved surface 13 at the end portion 10 of the second embodiment, the curved surface 13 functions to guide the Co-based amorphous material 2. Therefore, the function of preventing the Co-based amorphous material 2 from bending is the same as that shown in FIG. It is superior to a tapered shape 11 having a plane 12 at 10. The second embodiment is particularly effective when the tension of the Co-based amorphous material 2 is large.
[0033]
(Third embodiment)
FIG. 8 shows a third embodiment of the present invention, which is different from the tapered shape 11 having the flat surface 12 at the end portion 10 of FIG. 4 in that the tapered shape 11b having the flat surface 14 at the end portion 10 having the C surface 15 is provided. That was done. Other parts are the same as those in FIG. 4, and the same parts and shapes will be described using the same reference numerals.
[0034]
In the third embodiment, since the end portion 10 is provided with the C surface 15, the Co-based amorphous material 2 can be prevented from being bent and the bulge and the thickness of the curved surface 4 having the outermost diameter from increasing by easy processing or molding. The third embodiment is particularly effective when the tension of the Co-based amorphous material 2 is small.
[0035]
(Fourth embodiment)
FIG. 9 shows a bobbin 3 according to a fourth embodiment of the present invention before the Co-based amorphous 2 is wound. The difference from the bobbin 3 in FIG. 2 is that a space 16 is provided in the central portion of the concave portion 7 of the bobbin 3. Both ends of the bobbin 3 are provided with concave portions 7, and the cross-sectional shape in the width direction is the same as the H-shaped shape 9 in FIG. On both sides in the width direction of the concave portion 7, thick portions 8 are formed in the longitudinal direction. Other parts are the same as those in FIG. 2, and the same reference numerals are used for the same parts and shapes.
[0036]
FIG. 10 is a cross-sectional view of the end portion 10 of the fourth embodiment of the present invention cut in the longitudinal direction. The end portion 10 has a tapered shape 11 having a space 16 in the center portion and a flat surface 12 at the end portion 10. .
[0037]
In the fourth embodiment, since the space 16 is provided in the central portion of the bobbin 3, the weight of the antenna core 1 can be further reduced, and the deformation of the bobbin 3 in the longitudinal direction can be suppressed by the thick portion 8. Further, since the tapered shape 11 having the flat surface 12 at the end portion 10 is exhibited, it is possible to prevent the curved surface 4 having the outermost diameter after the Co-based amorphous material 2 has been wound from bulging or increasing in thickness.
[0038]
In the present invention, the bobbin 3 is made of a resin material of PPS with 30% glass fiber added. However, the present invention is not limited to this, and it is a lightweight and moldable resin material, for example, LCP, PBT or the like with glass fiber added. Good. The thick portions 8 on both sides of the concave portion 7 of the H-shaped shape 9 are not limited to the target shape, and even if the thick portions 8 have different widths and heights, they are included in the H-shaped shape of the present invention. Further, the tapered shape having a surface at an end portion of the present invention is not limited to FIGS. 4, 7, and 8, and any other shape may be used as long as the shape exhibits a tapered shape having a surface at an end portion. Good.
[0039]
【The invention's effect】
When the soft magnetic ribbon material is wound around a bobbin, the present invention does not cause displacement in the width direction of the soft magnetic ribbon material, is lightweight, compact, and has a certain strength in the longitudinal direction of the antenna core. In addition, it is possible to provide a magnetic core for an antenna in which a curved surface and a thickness of a soft magnetic ribbon material at a longitudinal end portion of the magnetic core for an antenna do not vary from product to product and an arbitrary curved surface as designed can be obtained.
[Brief description of the drawings]
FIG. 1 shows the configuration of an antenna using an antenna magnetic core of the present invention.
FIG. 2 shows a state before a Co-based amorphous is wound on a bobbin constituting a magnetic core for an antenna according to the present invention.
FIG. 3 is an enlarged cross-sectional view of the bobbin of FIG. 2 taken along line AA.
4 is an enlarged cross-sectional view of the bobbin taken along line BB of FIG. 2 and shows a state in which a Co-based amorphous is wound, and has a tapered shape having a flat surface at an end.
FIG. 5 is a diagram in which the shape of the BB cross section is a square shape.
FIG. 6 is a sectional view taken along a line BB in a triangular shape.
FIG. 7 is a tapered shape having a curved surface at an end according to a second embodiment of the present invention.
FIG. 8 is a third embodiment of the present invention having a tapered shape having a flat surface at an end having a C-plane.
FIG. 9 is a diagram showing a bobbin having a space in a central portion thereof before winding a Co-based amorphous according to a fourth embodiment of the present invention.
FIG. 10 shows a fourth embodiment of the present invention, which has a tapered shape having a flat surface at an end portion.
FIG. 11 is a diagram showing a configuration of a conventional antenna.
FIG. 12 shows a magnetic core for an antenna obtained by winding and laminating a soft magnetic ribbon material of a prior application (Japanese Patent Application No. 2002-309908).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Magnetic core for antennas 2 Co-based amorphous (soft magnetic ribbon material)
3 bobbin 7 concave portion 9 H-shaped shape 10 end portion 11 tapered shape having a flat surface at the end (tapered shape having a surface at the end)
12 plane

Claims (4)

In a magnetic core for an antenna composed of a band-shaped soft magnetic ribbon material and a bobbin for winding the soft magnetic ribbon material a plurality of times,
A magnetic core for an antenna, wherein the bobbin includes a concave portion for winding the soft magnetic ribbon material a plurality of times. The magnetic core for an antenna according to claim 1, wherein a cross-sectional shape of the bobbin in the width direction of the concave portion is an H-shape. The magnetic core for an antenna according to claim 2, wherein the bobbin is a resin molded product. The magnetic core for an antenna according to any one of claims 1 to 3, wherein a longitudinal cross-sectional shape of an end of the bobbin recess is a tapered shape having a surface at the end.

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