JP2009206974A - Magnetic body antenna, and antenna apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic body antenna which extends a communicable distance with an opposite side antenna such as a reader/writer side antenna by improving an antenna coupling coefficient in a distance, and to provide an antenna apparatus with the magnetic body antenna. <P>SOLUTION: First and second coils 13a, 13b are respectively constituted by winding flexible substrates on which coil conductors are formed around the peripheries of magnetic cores 14a, 14b each of which is composed of plate-like ferrite. The coil 13a is constituted by winding a plurality of coil conductors 131, 132, 133, ... and normals of the loop surfaces of the coils 13a, 13b are respectively inclined in a direction of a circuit board 21. Thereby, circulating routes of magnetic fluxes entering/exiting to/from the outside ends of the coils 13a, 13b are enlarged, coupling quantity with a reader/writer side antenna 20 which exists in a far distance is increased, and communication distance performance is improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetic antenna used in an RFID (Radio Frequency Identification) system or the like that communicates with an external device via an electromagnetic field signal, and an antenna device including the magnetic antenna.

  Patent Document 1 discloses an antenna mounted on a portable electronic device used in an RFID system. FIG. 1 is a front view showing the structure of the antenna device described in Patent Document 1. FIG.

  1A and 1B, the flexible substrate on which the coil conductor pattern is formed is attached so as to be wound around the magnetic cores 4a and 4b, respectively, and the first coil portion 2a and the second coil portion 2b are attached. Is forming. By arranging (mounting) the two coil portions 2a and 2b on the circuit board 21 with a predetermined interval, an antenna device is configured.

In FIG. 1, a broken line indicates a magnetic field (lines of magnetic force) generated by the coil portions 2a and 2b of the antenna, or a magnetic field (lines of magnetic force) received by the coil portions 2a and 2b of the antenna in a state where the antenna device is placed close to the antenna 20 on the reader / writer side. ).
Japanese Patent No. 3957000

  When such an antenna device is mounted and used in a portable electronic device such as a mobile phone terminal or a portable information terminal, the reader / writer and the antenna at a distant place are used in order to extend the communicable distance with the reader / writer. It is necessary to improve the coupling coefficient. In order to improve the coupling coefficient in the distance between the two coils, it is necessary to circulate the magnetic flux of the antenna alone in the distance.

  However, the antenna device disclosed in Patent Document 1 has a coil having a loop surface that is perpendicular to the axial direction of the magnetic core (ferrite core), and is mounted directly on the circuit board or is It is arranged near the position. According to this structure, it has been found that the magnetic flux circulation path tends to be smaller than the optimum position, which is disadvantageous for increasing the communication distance, and the antenna performance is impaired.

  Further, as shown in FIG. 1B, the first and second coil portions 2a and 2b face the outside of the first and second coil portions 2a and 2b from the intermediate positions of the first and second coil portions 2a and 2b. It has been found that when the direction of the normal line of the loop surface of the coil portions 2a and 2b is directed away from the circuit board 21, the above-described tendency becomes more remarkable.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic antenna having an increased communication distance by improving a coupling coefficient in the distance to a partner antenna such as a reader / writer side antenna, and an antenna device including the same. It is in.

In order to solve the above problems, the present invention is configured as follows.
(1) At least two first and second coils wound around the magnetic core are mounted on or arranged in proximity to the circuit board, and the inner and outer ends of the first and second coils The first and second coils are connected so that the induced voltages of the first and second coils generated when the magnetic flux is transmitted between them are combined with the same polarity (or the first and second coils). In the magnetic antenna, the first and second coils are connected so that the magnetic flux is transmitted between the inner and outer ends of the first and second coils when the coil is energized.
The normal lines of the loop surfaces of the first and second coils are inclined in the circuit board direction from the inner ends of the first and second coils toward the outer end direction.

  With this configuration, the direction of the magnetic flux generated from the outer end of the coil (through the coil) is directed toward the circuit board at the mounting destination. Therefore, the magnetic flux circulation path becomes larger, the amount of coupling with the antenna located farther increases, and the communication distance performance is improved.

(2) The first and second coils are each formed by winding a coil conductor a plurality of times,
The coil in which the normal line of the loop surface is inclined toward the circuit board may be only the coil portion formed by the coil conductor wound around the outer end.

  In general, in a coil wound in a plurality of turns, the inductance value is reduced by making the loop surface of the coil slant. However, according to the above configuration, only the coil conductor wound near the outer end is inclined. Therefore, the amount of decrease in inductance value can be suppressed. Therefore, the number of coil turns and the line length of the coil conductor for obtaining a necessary inductance value are not increased, and the antenna is not enlarged.

(3) The coil conductor wound in the vicinity of the outer end may be formed such that the line width on the side opposite to the circuit board side is wider than the line width on the circuit board side.

  With this configuration, the loop surface of the coil is equivalently slanted, but only the outermost coil conductor only has a wider line width on the half surface, so that the magnetic flux circulation path is increased without lowering the inductance value. can do.

(4) An antenna device of the present invention includes the magnetic antenna having the above-described configuration and a circuit board on which the magnetic antenna is mounted, and the magnetic core around which the first and second coils are wound. The outer ends of the first and second coils are configured to be located on the outer edge of the circuit board or on the outside of the outer edge in plan view.

  With this configuration, the magnetic flux directed toward the circuit board from the outer end of the coil is not blocked by the circuit board electrode (ground pattern), the magnetic flux density toward the circuit board is increased, and the magnetic flux circulation path is increased. Thus, the communication distance performance is further improved.

  According to the present invention, the magnetic flux generated from the coil (transmitted through the coil) is directed from the outer end of the coil toward the circuit board at the mounting destination, and the magnetic flux circulation path becomes larger. For this reason, the amount of coupling with a farther antenna increases, and the communication distance performance improves.

<< First Embodiment >>
FIG. 2 is a diagram illustrating the configuration of the magnetic antenna and the antenna device according to the first embodiment.
FIG. 2A is a front view of the magnetic antenna 22, the circuit board 21 on which the magnetic antenna 22 is mounted, and the antenna device 101 constituted by these. Around the magnetic cores 14a and 14b made of flat ferrite, coils 13a and 13b are respectively configured by winding a flexible substrate on which a coil conductor is formed.

  As will be described later, the first and second coils 13a and 13b transmit magnetic flux between the inner end (the side close to the substantially intermediate position C when mounted on the circuit board 21) and the outer end. The two coils 13a and 13b are connected so that the induced voltages of the first and second coils 13a and 13b generated when the two are combined are combined.

  FIG. 2B is an enlarged view of the vicinity of the end of the coil 13a. The coil 13a is formed by winding a plurality of coil conductors of coil conductors 131, 132, 133..., The broken line in the figure is the pattern of the coil conductor on the rear end face of the magnetic core 14a, and the solid line is the magnetic core. The pattern of the coil conductor at the end face (front face) in front of 14a is shown.

The coil 13b has the same configuration as the coil 13a. However, the coil 13a is symmetrical.
In this way, the normal lines N of the loop surfaces of the coils 13a and 13b are inclined in the direction of the circuit board 21, respectively.

  Thus, the normal lines N of the loop surfaces of the first and second coils 13a and 13b are inclined in the direction of the circuit board 21, respectively, so that the outer sides of the coils 13a and 13b as shown in FIG. The direction of the magnetic flux entering and exiting from the end is the normal direction and the direction away from the reader / writer side antenna 20.

  Further, the outer ends of the magnetic cores 14a and 14b around which the first and second coils 13a and 13b are wound are located on the outer edge of the circuit board 21 or on the outside of the outer edge in a plan view (the protrusions). ing.). Therefore, the magnetic flux directed from the outer end of the coil toward the circuit board is not blocked by the circuit board electrode (ground pattern), the magnetic flux density toward the circuit board increases, and the magnetic flux circulation path becomes larger.

  By the action described above, the magnetic flux circulation path becomes larger, the amount of coupling with the reader / writer side antenna 20 located farther away increases, and the communication distance performance improves.

  FIG. 3 is a diagram showing an example of a pattern on the flexible substrate of the coil 13a shown in FIG. 3A is a developed plan view of the flexible substrate, FIG. 3B is a top view in a state of being bent around the magnetic core 14a, FIG. 3C is a front view thereof, and FIG. (D) is the rear view. 3B, 3C, and 3D are shown including the magnetic cores 14a and 14b.

As shown in FIG. 3B, the coil conductors are connected to each other as follows in a state where the flexible substrate 15 is bent so as to surround the magnetic core 14.
Symbols p1 to p4 and q1 to q4 in FIG. 3A are end portions (connection points) of the coil conductors 131 to 133 formed on the flexible substrate 15, and in the state shown in FIG. The one end portions p1 to p3 of the coil conductors 131 to 133 are electrically connected to the other end portions q1 to q3 of the coil conductors 132 to 134, respectively, and the one end portion p4 of the coil conductor 134 is the end of the connection line 135. It conducts to the part q4.

  One end of the coil conductor 131 is led out to the protruding portion 9 of the flexible substrate 15. The end portion of the coil conductor of the protruding portion 9 is connected to a connection portion on a circuit board that is a mounting destination. In this way, the polarity to which the induced voltages of the first and second coils 13a and 13b generated when the magnetic flux passes between the inner and outer ends of the first and second coils 13a and 13b are added. Thus, the first and second coils 13a and 13b are connected.

  As described above, since the patterns of the coil conductors 131 to 134 are arranged at positions shifted in the left-right direction between the upper surface and the lower surface of the magnetic core, as described above, the loop surface facing the outer end from the inner end of the coil. The normal is inclined to face the circuit board.

<< Second Embodiment >>
FIG. 4 is a front view showing the configuration of the magnetic antenna 23 and the antenna device 102 according to the second embodiment.
Each of the first and second coils 13a and 13b includes a plurality of coil conductors 131 to 134. Of these coil conductors, only the coil conductor 131 wound around the outermost end is the first. As in the case of the embodiment, the normal line N of the loop surface is inclined so as to face the circuit board 21 direction. The other coil conductors 132 to 134 are each formed with a pattern so that the normal line N of the loop surface faces the axial direction of the magnetic cores 14a and 14b, as in the conventional coil. Other configurations are the same as those of the first embodiment.

  With this configuration, most of the plurality of coil conductors have their loop surfaces perpendicular to the axial direction of the magnetic cores 14a and 14b (the normal of the loop surface is the axial direction of the magnetic core). Therefore, it is possible to increase the magnetic flux circulation path without reducing the inductance value of the coil.

  Thus, the magnetic flux passing through the loop surface by the coil conductor located near the outer ends of the coils 13a and 13b is directed to the circuit board 21 side and is not affected by the electrode (ground pattern) of the circuit board 21. The route will spread greatly.

  Moreover, since only the coil conductor wound around the outer end portion is inclined, the amount of decrease in the inductance value can be suppressed. Therefore, the number of coil turns and the line length of the coil conductor for obtaining a necessary inductance value are not increased, and the antenna is not enlarged.

<< Third Embodiment >>
FIG. 5 is a front view showing the configuration of the magnetic antenna 24 and the antenna device 103 according to the third embodiment.
Each of the first and second coils 13a and 13b includes a plurality of coil conductors 131 to 134. Of these coil conductors, the coil conductor 131 wound around the outermost end is a circuit board 21. The line width on the side opposite to the side is formed wider than the line width on the circuit board 21 side. About the other coil conductors 132-134, the pattern of the same line | wire width is formed also about the circuit board 21 side and its opposite surface side like the conventional coil.

  FIG. 6 is a diagram showing an example of a pattern on the flexible substrate of the coil 13a shown in FIG. 6A is a developed plan view of the flexible substrate, FIG. 6B is a top view in a state of being bent around the magnetic core 14a, FIG. 6C is a front view thereof, and FIG. (D) is the rear view. 6B, 6C, and 6D are shown including the magnetic cores 14a and 14b.

  As shown in FIG. 6B, in the state where the flexible substrate 15 is bent so as to surround the magnetic core 14, the coil conductors are connected as follows. Reference numerals p1 to p4 and q1 to q4 in FIG. 6 (A) are end portions (connection points) of the coil conductors 131 to 133 formed on the flexible substrate 15, and in the state shown in FIG. 6 (B). The one end portions p1 to p3 of the coil conductors 131 to 133 are electrically connected to the other end portions q1 to q3 of the coil conductors 132 to 134, respectively, and the one end portion p4 of the coil conductor 134 is the end of the connection line 135. It conducts to the part q4.

  One end of the coil conductor 131 is led out to the protruding portion 9 of the flexible substrate 15. The end portion of the coil conductor of the protruding portion 9 is connected to a connection portion on a circuit board that is a mounting destination.

  As described above, the coil conductor 131 near the outermost end has a line width opposite to the circuit board 21 side that is wider than the line width on the circuit board 21 side. Is equivalent to the normal line of the circuit board 21 side. As a result, as shown in FIG. 5, the magnetic flux circulation path becomes larger, the amount of coupling with the farther reader / writer side antenna 20 increases, and the communication distance performance improves.

<< Fourth Embodiment >>
FIG. 7 is a front view showing the configuration of the magnetic antenna 25 and the antenna device 104 according to the fourth embodiment.
Each of the first and second coils 13a and 13b includes a plurality of coil conductors 131 to 134. As in the case of the second embodiment shown in FIG. 4, the coil conductors 131 to 134 are configured so that the coil conductor 131 wound around the outermost end portion has a normal line N of the loop surface. It inclines so that it may face the circuit board 21 direction.

  4 is different from the configuration shown in FIG. 4 in that the outer end faces of the magnetic cores 14a and 14b are inclined toward the circuit board 21 side. By using such magnetic cores 14a and 14b, the magnetic flux directed from the outer end of the coil toward the circuit board is more effectively directed toward the circuit board 21, and the circulation path of the magnetic flux is larger. Become.

  In the example shown in FIGS. 3 and 6, the first and second coils 13a and 13b are connected in series. However, the gap between the inner end and the outer end of the first and second coils is shown. If the polarities are such that the induced voltages of the first and second coils generated when the magnetic flux is transmitted are added (synthesized), they may be connected in parallel.

  In each embodiment, the counterpart antenna is the reader / writer side antenna. However, the present invention is not limited to the communication with the reader / writer side antenna of the RFID system, and a portable electronic device provided with the same antenna. It can also be applied to antennas that communicate with each other.

  Further, the magnetic antenna is not limited to being directly mounted on the circuit board, and may be configured to be disposed close to the circuit board.

It is a front view which shows the structure of the antenna apparatus described in patent document 1. It is a figure which shows the structure of the magnetic body antenna and antenna apparatus which concern on 1st Embodiment. It is a figure which shows the example of the pattern on the flexible substrate of the coil 13a shown in FIG. It is a front view which shows the structure of the magnetic body antenna and antenna apparatus which concern on 2nd Embodiment. It is a front view which shows the structure of the magnetic body antenna and antenna apparatus which concern on 3rd Embodiment. It is a figure which shows the example of the pattern on the flexible substrate of the coil 13a shown in FIG. It is a front view which shows the structure of the magnetic body antenna and antenna apparatus which concern on 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 ... Projection part 13a, 13b ... Coil 14a, 14b ... Magnetic material core 15 ... Flexible board 20 ... Reader / writer side antenna 21 ... Circuit board 22-25 ... Magnetic material antenna 101-104 ... Antenna apparatus 131-134 ... Coil conductor 135 ... Connection line N ... Normal

Claims (4)

First and second at least two coils wound around the magnetic core are mounted on or arranged in proximity to the circuit board, and between the inner and outer ends of the first and second coils. In the magnetic antenna to which the first and second coils are connected so that the induced voltages of the first and second coils generated when the magnetic flux is transmitted are synthesized with the same polarity,
A magnetic body characterized in that normal lines of the loop surfaces of the first and second coils are inclined in the circuit board direction from the inner ends of the first and second coils to the outer end direction. antenna. Each of the first and second coils is formed by winding a coil conductor a plurality of times.
2. The magnetic antenna according to claim 1, wherein the coil whose normal of the loop surface is inclined toward the circuit board is a coil portion formed by the coil conductor wound around the outer end.   3. The magnetic antenna according to claim 2, wherein the coil conductor wound in the vicinity of the outer end has a line width on the side opposite to the circuit board side that is wider than a line width on the circuit board side. A magnetic antenna according to any one of claims 1 to 3, and a circuit board on which the magnetic antenna is mounted,
The outer ends of the first and second coils of the magnetic core around which the first and second coils are wound are located on the outer edge of the circuit board or outside the outer edge in plan view. An antenna device characterized by comprising:

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