JP5071092B2 - RFID antenna and antenna coil manufacturing method - Google Patents

Description

  The present invention relates to an RFID (Radio Frequency Identification) antenna and an antenna coil manufacturing method used for a portable terminal that exchanges signals with a reader / writer.

  Conventionally, as an example of an antenna coil portion of an RFID antenna employed in a portable terminal, a so-called FPC (Flexible Printed Circuit) in which a coil is formed by etching using 35 μm rolled copper as a conductor portion; Version) type was used.

Conventionally, a portable terminal provided with an IC antenna coil has been proposed, for example, in Patent Document 1 below, and a transponder antenna having a spiral coil, for example, described in Patent Document 2 below, has been proposed. Has been proposed.
JP 2006-74534 A JP 2002-290131 A

In the above configuration of the antenna coil of the conventional FPC type, high-frequency loss at f = 13.56MH _Z is large, the coil unit resistance (R) is increased. For this reason, there is a problem that loss due to the skin effect of the conductor portion becomes large and communication characteristics are deteriorated (communication distance is shortened), and material costs are high.

  In addition, it takes a lot of time to manufacture a plurality of antenna coils with good performance.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object thereof is to provide an RFID antenna and an antenna coil manufacturing method in which characteristics such as a Q value and an inductance L value of an antenna coil portion are improved.

The RFID antenna according to claim 1 for solving the above-mentioned problem is an RFID antenna for exchanging signals with an RFID device, and is a plate-like magnetic element disposed on the device side where the antenna is installed. An antenna coil portion fixed to a material and a surface of the magnetic material opposite to the installation surface by winding a single conducting wire in a plurality of turns at a uniform interval along the plate surface of the magnetic material The one conductor is formed in a uniform cross-sectional shape having a major axis diameter and a minor axis diameter in the extending direction, and the major axis diameter is orthogonal to the plate surface of the magnetic material , Between the adjacent conductive wires along the minor axis radial direction, a resin for fixing the adjacent conductive wires is interposed, and the surface of the single conductive wire opposite to the magnetic material is exposed.

  With the above configuration, characteristics such as the Q value and inductance L value of the antenna coil section are improved as compared with the conventional FPC type antenna and the like, and the communicable range is expanded accordingly.

  Moreover, since it consists of a plate-shaped magnetic material and the antenna coil part arrange | positioned on the surface, it is thin and can attain space saving.

Moreover, since one conducting wire is wound at a uniform interval, the Q characteristic of the antenna coil portion is further improved.

In addition, since one conductor is formed in a cross-sectional shape having a major axis diameter and a minor axis diameter, and the major axis diameter is orthogonal to the plate surface of the magnetic material, the Q value of the antenna coil portion becomes higher and the installation surface The strength of the magnetic field in the direction opposite to is increased, and the performance is improved.

The RFID antenna according to claim 2, in claim 1, wherein the antenna coil unit that is arranged in the mobile terminal.

  According to the above configuration, communication characteristics in the mobile terminal are improved.

According to a third aspect of the present invention, there is provided a method for manufacturing an antenna coil, wherein a single conductor formed in a uniform cross-sectional shape having a major axis diameter and a minor axis diameter is wound in a ring shape at a uniform interval along a plane. The first antenna coil portion in which the major axis diameter is orthogonal to the plane and a resin for fixing the neighboring conductors is interposed between the neighboring conductors along the minor axis radial direction. And a winding end of the first antenna coil portion of the one conducting wire is laminated on the winding surface of the first antenna coil portion, and along the winding surface. Then, the adjacent conducting wires are fixed between the adjacent conducting wires along the minor axis radial direction, with the major axis diameter orthogonal to the winding surface. a second winding step of the resin to create a second antenna coil portion being interposed, said one conductor Cutting the winding terminal end of the first antenna coil part and a step of obtaining two antenna coils.

According to a fourth aspect of the present invention, there is provided a method for manufacturing an antenna coil, comprising: winding a single conductor formed in a uniform cross-sectional shape having a major axis diameter and a minor axis diameter in a ring shape at a uniform interval along a plane. The first antenna coil portion in which the major axis diameter is orthogonal to the plane and a resin for fixing the neighboring conductors is interposed between the neighboring conductors along the minor axis radial direction. And a winding end of the first antenna coil portion of the one conducting wire is laminated on the winding surface of the first antenna coil portion, and along the winding surface. Then, the adjacent conducting wires are fixed between the adjacent conducting wires along the minor axis radial direction, with the major axis diameter orthogonal to the winding surface. a second winding step of the resin to create a second antenna coil portion being interposed, said second winding After the step, the second winding step is repeatedly executed to form n (n is a positive number of 3 or more) antenna coil portions, and the n antenna coils of the one conducting wire. Cutting each winding end of the section to obtain n antenna coils .

  According to the above configuration, a plurality of antenna coils can be easily manufactured by a simple process.

(1) According to the first aspect of the invention, the characteristics such as the Q value and the inductance L value of the antenna coil section are improved as compared with the conventional FPC type antenna and the like, and accordingly the communicable range is also increased. spread. Moreover, since it consists of a plate-shaped magnetic material and the antenna coil part arrange | positioned on the surface, it is thin and can attain space saving. Moreover, since one conducting wire is wound at a uniform interval, the Q characteristic of the antenna coil portion is further improved. In addition , since one conductor is formed in a cross-sectional shape having a major axis diameter and a minor axis diameter, and the major axis diameter is orthogonal to the plate surface of the magnetic material, the Q value of the antenna coil portion becomes higher and the installation surface The strength of the magnetic field in the direction opposite to is increased, and the performance is improved.
(2) According to the invention described in claim 2 , the communication characteristics in the portable terminal are improved.
(3) According to the third and fourth aspects of the invention, a plurality of antenna coils can be easily manufactured by a simple process.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

  1 and 2 show an embodiment in which the present invention is applied to a portable terminal that communicates with a reader / writer by electromagnetic coupling when the main body is held over a reader / writer (reading / writing device). 1A shows a plane of the portable terminal 100 on which the antenna of the present invention is installed, FIG. 1B shows a cross section of the antenna of the present invention, and FIG. 2 shows a plane of the antenna coil section.

  In FIG. 1, the magnetic material 1 is disposed in a portion of the speaker unit 50 of the mobile terminal 100 excluding the speakers 50 a and 50 b. On the outer periphery of the speakers 50 a and 50 b on the magnetic material 1, an antenna coil portion 2 a in which one conductive wire 2 is wound in a ring several times and fixed with, for example, a resin 3 is disposed.

  The antenna coil portion 2a and the magnetic material 1 are fixed with an adhesive or the like. The resin 3 is made of, for example, PET, thermosetting resin, adhesive, or the like. Reference numeral 60 denotes a battery pack.

  One conductor 2 of the antenna coil portion 2a is wound at a predetermined uniform interval, thereby improving the Q characteristic of the antenna.

  Since the antenna of the present invention can be provided on the speaker unit 50, which is a limited space, of the mobile terminal 100, it can be compactly arranged without taking a useless space in the width direction.

  For example, the antenna coil portion 2a removes the inner frame body 70a after winding a single lead wire 2 at a predetermined interval around the outer periphery of the inner frame body 70a formed in an annular shape as shown in FIG. Manufactured.

  When a plurality of antenna coil portions are manufactured, for example, as shown in FIG. 3, the first antenna coil portion is formed by winding one conductor 2 around the outer periphery of the inner frame 70a a plurality of times at predetermined intervals. 2a is formed, and the winding end of the antenna coil portion 2a of the conductive wire 2 is laminated on the winding surface of the first antenna coil portion 2a, and the second antenna coil portion 2b is wound in a plurality of rounds. By forming and repeating these steps to form n antenna coil portions (2a to 2n), and then cutting each winding end of each antenna coil portion, it is possible to easily obtain n antenna coil portions. it can.

  In FIG. 3, reference numeral 70b denotes an outer frame for storage that matches the shape of each of the antenna coil portions 2a to 2n.

Further, the end of the conductor 2 of each antenna coil section after the cutting is fixed by a reinforcing plate 80. 2 and 3, the magnetic material 1 and the resin 3 are not shown. F = 13.56MH of the antenna coil part 2a of the present invention configured as described above, the conventional FFC cable (Flexible Flat Cable) type, and the wire type antenna coil part. FIG. 4 shows the results of measuring the static characteristics (antenna coil L value and antenna coil Q value) in _Z with an impedance analyzer.

  As can be seen from FIG. 4, the antenna coil portion 2a of the present invention has a higher L value and Q value than those of the conventional FFC type or wire type.

  Also, RC-460C is prepared as a reader / writer, and a mobile Felica terminal using the antenna coil unit 2a of the present invention, a conventional FFC type, and a wire type antenna coil unit is prepared as a portable terminal, The result of having performed communication between them and measuring the communicable range (distance) is shown in FIG.

  According to FIG. 5, it can be seen that the antenna coil portion 2a of the present invention has a wider communicable range (distance) than the conventional FFC type or wire type.

  Each of the measurement samples in FIGS. 4 and 5 uses a 4-turn antenna coil section.

  For example, the cross-sectional shape of one conductor 2 of the antenna coil portion is as shown in FIG. 6, (a) is a plan view, (b) to (d) are AA ′ cross-sectional enlarged views of (a), and the resin 3 is not shown.

  FIG. 6B shows an example (type A) of a conducting wire 20A having a circular cross section. FIG. 6C shows an example (type B) in which the conducting wire 20B having a major axis diameter and a minor axis diameter is disposed so that the major axis diameter is along the direction perpendicular to the plate surface of the magnetic material 1. . FIG. 6 (d) shows an example (type C) in which a conductor 20 </ b> C having a major axis diameter and a minor axis diameter is arranged so that the major axis diameter is parallel to the plate surface of the magnetic material 1.

The antenna coil unit type A~ type C of Figure 6 shows the results of measurement by the static characteristic impedance analyzer at f = 13.56MH _Z in FIG. According to FIG. 7, it can be seen that the L value and Q value of Type B are particularly high.

  As shown in the magnetic field distribution diagram of FIG. 8, this is a type B (FIG. 8 (FIG. 8 (FIG. 8) in which the major axis diameter of the conducting wire 20 </ b> B constituting the antenna coil portion is along the direction orthogonal to the plate surface of the magnetic material 1. This is because a)) has a higher Q value and a stronger magnetic field strength than Type C (FIG. 8B) in which the major axis diameter of the conductor 20C is arranged parallel to the plate surface of the magnetic material 1. .

  Note that the number of windings of one conductor 2 of the antenna coil portion is appropriately determined according to the value of the inductance L on the reader / writer side.

  In addition, the antenna coil unit of the present invention is not limited to being applied to a mobile terminal, but can be applied to a TV remote control, a digital camera, a non-contact IC card, an IC tag, and the like. The effect is obtained.

An embodiment of the antenna of the present invention is shown, (a) is a plan view of a mobile terminal, (b) is a cross-sectional view of the main part. The principal part top view of one embodiment of the antenna of this invention. Explanatory drawing which shows the manufacturing method of the antenna coil of this invention. The graph showing the static characteristic comparison of the antenna coil in the example of embodiment of this invention, and the conventional antenna coil. The graph showing the comparison of the communicable range of the antenna coil in the example of embodiment of this invention, and the conventional antenna coil. Explanatory drawing which shows the Example of the antenna coil part in embodiment of this invention. The graph which shows the static characteristic of each type of the Example of FIG. Explanatory drawing showing the magnetic field distribution of each type of the Example of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Magnetic material, 2, 20A, 20B, 20C ... Conductor, 2a-2n ... Antenna coil part, 3 ... Resin, 50 ... Speaker part, 50a, 50b ... Speaker, 70a ... Inner frame, 70b ... Outer frame, 80: Reinforcing plate, 100: Mobile terminal.

Claims (4)

An RFID antenna for exchanging signals with an RFID device,
A plate-like magnetic material disposed on the device side where the antenna is installed; and
An antenna coil portion fixed on a surface of the magnetic material opposite to the installation surface by winding a single conducting wire in a ring shape at a uniform interval along the plate surface of the magnetic material; Prepared,
The one conducting wire is formed in a uniform cross-sectional shape having a major axis diameter and a minor axis diameter over the extending direction,
The major axis diameter is orthogonal to the plate surface of the magnetic material ,
Between the adjacent conductive wires along the minor axis radial direction, a resin for fixing the adjacent conductive wires is interposed, and the surface opposite to the magnetic material of the one conductive wire is exposed.
RFID antenna. The RFID antenna according to claim 1 , wherein the antenna coil unit is disposed in a mobile terminal. A single conductor formed in a uniform cross-sectional shape having a major axis diameter and a minor axis diameter is wound in an annular manner at a uniform interval along the plane, and the major axis diameter is orthogonal to the plane . A first winding step of creating a first antenna coil part in which a resin for fixing the adjacent conductive wires is interposed between the conductive wires adjacent to each other along the minor axis radial direction ;
The winding end of the first antenna coil portion of the one conducting wire is laminated on the winding surface of the first antenna coil portion, and is wound in a plurality of turns at regular intervals along the winding surface. The second antenna in which the major axis diameter is orthogonal to the winding surface and a resin for fixing the neighboring conductors is interposed between the neighboring conductors along the minor axis radial direction. A second winding step for creating a coil portion;
Cutting the winding end of the first antenna coil portion of the one conducting wire to obtain two antenna coils. A single conductor formed in a uniform cross-sectional shape having a major axis diameter and a minor axis diameter is wound in an annular manner at a uniform interval along the plane, and the major axis diameter is orthogonal to the plane . A first winding step of creating a first antenna coil part in which a resin for fixing the adjacent conductive wires is interposed between the conductive wires adjacent to each other along the minor axis radial direction ;
The winding end of the first antenna coil portion of the one conducting wire is laminated on the winding surface of the first antenna coil portion, and is wound in a plurality of turns at regular intervals along the winding surface. The second antenna in which the major axis diameter is orthogonal to the winding surface and a resin for fixing the neighboring conductors is interposed between the neighboring conductors along the minor axis radial direction. A second winding step for creating a coil portion;
After the second winding step, repeatedly performing the second winding step to form n (n is a positive number of 3 or more) antenna coil portions;
Cutting each winding end of the n antenna coil portions of the one conducting wire to obtain n antenna coils.