JP4214913B2 - Magnetic field antenna, wireless system and communication system using the same - Google Patents

Description

  The present invention relates to a magnetic field antenna that receives and transmits a magnetic field component, and more particularly to a magnetic field antenna suitable for use in a non-contact IC card system and an IC tag, and a wireless system and a communication system configured using the magnetic field antenna. .

Since the sensor coil of a conventional non-contact IC card has a planar surface, the coil is wound around the surface of the card, and therefore a magnetic field is generated in a direction perpendicular to the card surface. On the other hand, a sensor antenna having a similar shape must be provided on the wall side (external device side) in order to receive this magnetic field and send signals and power to the card. When the sensor antenna is provided on the wall surface facing the card, the magnetic field is perpendicular to the wall surface. Therefore, the sensor coil corresponding to such a magnetic field is generally a coil wound in the same direction as the wall surface.
JP 2003-318634 A

  However, if the wall surface is made of metal, a reverse current is generated due to the mirror (image) effect, the magnetic field is canceled, and the sensor does not operate effectively. Recent buildings have many iron walls, and electronic devices have shield plates, etc. If a sensor coil is attached here, communication between the card and the sensor becomes impossible, or the distance between the card and the sensor becomes extremely short. .

  SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic field antenna that does not protrude so much from a metal surface such as an iron wall or a shield plate, and can communicate well with a card even when the antenna is arranged in a plane, and a wireless system and communication configured using the same To provide a system.

  In order to achieve the above object, a magnetic field antenna according to the present invention is a magnetic field antenna for transmitting and receiving a magnetic field component, and has a plurality of linear portions each wound with a coil, and one end of each linear portion is magnetic. A magnetic body connected to the metal surface via an insulator, the magnetic body generates a magnetic field in a direction to cancel each other in a direction in which the plurality of linear portions intersect, and The straight line portion is not arranged on an extension line of another straight line portion.

  In the magnetic field antenna according to the present invention, the windings of the respective linear portions are connected in series, and a resonance capacitor is connected in parallel between both ends of the series-connected windings or in series with the series-connected windings. It is characterized by being.

  In the magnetic field antenna of the present invention, the windings of the respective linear portions are connected in parallel, and a resonance capacitor is connected in parallel between both ends of each winding for each winding or in series with the windings for each winding. It is characterized by that.

  The magnetic field antenna of the present invention is characterized in that a magnetic material is attached to a surface opposite to the metal surface of the metal plate having the metal surface.

  The magnetic field antenna of the present invention is characterized in that the magnetic body is a ferrite magnetic body or a metal magnetic body other than a ferrite magnetic body.

  In the magnetic field antenna of the present invention, the magnetic material is dispersed in a thermoplastic resin or a thermosetting resin by dispersing the magnetic material in a spherical, flat or crushed shape into a solid, It is characterized by being made into a product.

  The magnetic field antenna of the present invention is characterized in that an adhesive is applied to a surface of the metal having the metal surface opposite to the metal surface, and the magnetic field antenna is attached to the object by the adhesive. It is what.

  In the magnetic field antenna of the present invention, an adhesive is applied to the surface of the magnetic body opposite to the metal, and the magnetic field antenna is attached to the object with the adhesive. It is characterized by this.

  In addition, the wireless system of the present invention has a plurality of linear portions each wound with a winding, and a magnetic body in which one end of each linear portion is magnetically connected is disposed on a metal surface via an insulator. In addition, the magnetic body generates a magnetic field in a direction that cancels each other in a direction in which the plurality of linear portions intersect, and any linear portion is in series with a magnetic field antenna that is not disposed on an extension line of the other linear portion. The wireless system IC chip is mounted between both ends of the connected windings or both ends of each winding.

  Further, the communication system of the present invention has a plurality of linear portions each wound with a winding, and a magnetic body in which one end of each linear portion is magnetically connected is disposed on a metal surface via an insulator. In addition, the magnetic body generates a magnetic field in a direction that cancels each other in a direction in which the plurality of linear portions intersect, and any linear portion is in series with a magnetic field antenna that is not disposed on an extension line of the other linear portion. A transmission / reception circuit of a communication system is connected between both ends of the connected windings or both ends of each winding.

  According to the magnetic field antenna of the present invention, a strong magnetic field modulated by information can be generated in a direction perpendicular to the metal surface, so that it can be effectively used for a system such as a non-contact card such as a commuter pass or an IC tag. The reliability of the wireless system and communication system configured using the antenna can be increased.

Hereinafter, the present invention will be described in detail based on an embodiment of the invention with reference to the accompanying drawings.
Prior to describing the present invention, the technology described in Japanese Patent Application Laid-Open No. 2003-318634 of the prior application related to the present invention will be described.

  As shown in FIG. 5, when the coil is arranged on the metal surface and the cross section of the coil is perpendicular to the metal surface, the magnetic field is doubled by adding the magnetic field of the image. FIG. 5A shows the case of a square loop, and FIG. 5B shows the case of a circular loop. In either case, an induced voltage is generated in the coil by the surface current i. Alternatively, the magnetic field H is generated by the coil current I, and a magnetic current or current i is generated on the metal surface.

Furthermore, in the technique described in Japanese Patent Application Laid-Open No. 2003-318634, the magnetic field generated in a direction parallel to the metal surface is opposed to change the direction of the magnetic field to a right angle and generate a magnetic field in a direction perpendicular to the metal surface. .
FIG. 6 shows an example of the arrangement of sensor coils in that case.

  Specifically, a coil L is wound around a core of ferrite or the like, the coils are arranged so as to face each other in a straight line, and a magnetic field H caused by a current I is generated so that the direction of the magnetic field H is opposed. It can be seen that a perpendicular magnetic field is generated at the center. The excitation of these coils may be connected in parallel or in series.

  FIG. 7A shows a case in which two pairs (four) of coils are arranged at an equal distance r from the center. By increasing the number of pairs in this manner, a strong magnetic field can be created by adding a central magnetic field. Although FIG. 7A shows the case of two pairs, the number of pairs may be increased. Since the equidistant position from the center is a circle, the coils may be arranged substantially on the circle. FIG. 7B shows a case where a magnetic path is formed of ferrite so that a vertical magnetic field is easily generated between the core and the center of the coil.

  The above is the technology of the technique described in Japanese Patent Application Laid-Open No. 2003-318634, but what is important here is that the direction of the magnetic field is changed to a right angle by arranging the coils on a straight line in the direction in which the magnetic field cancels. It is that.

However, the present inventors examined the technique described in Japanese Patent Application Laid-Open No. 2003-318634 in detail and conducted additional experiments. As a result, in order to change the magnetic field from a direction parallel to the metal surface to a vertical direction, Even if the coils are not arranged so as to face each other on a straight line, magnetic materials having a plurality of straight portions each wound with a wire and one end of the straight portions being magnetically connected cancel each other's magnetic field. The magnetic field antenna of the present invention was invented by paying attention to the fact that it can be obtained by arranging it on a metal surface through an insulator in the direction.
In the following, two embodiments will be described.

FIG. 1 shows a first embodiment of the magnetic field antenna of the present invention.
The embodiment shown in FIG. 1 shows a case where a magnetic field antenna is formed by arranging cores wound with coils around respective linear portions at an angle of 120 ° on a metal surface.

In FIG. 1, 1 is a magnetic core, 2 is a coil (winding), 3 is an insulator, and 4 is a metal plate.
In the first embodiment, the core 1 made of a magnetic material has three straight portions, and is magnetically connected at a location where the straight portions intersect.
Here, the core 1 made of a magnetic material is composed of a ferrite magnetic material or a metal magnetic material other than the ferrite magnetic material.

When winding the coil 2 around the core 1, it is necessary to wind the coil so that the magnetic fields cancel each other (the direction indicated by the broken line arrow in FIGS. 2 and 3 to be described later) at the portion where the core intersects. .
By winding in this way, the direction of the magnetic field can be changed from a direction parallel to the surface of the metal plate 4 to a perpendicular direction.

  Further, the magnetic material composing the core 1 in a spherical shape, a flat shape, or a crushed shape is dispersed in a thermoplastic resin or a thermosetting resin and solidified. By using a thing, a magnetic field antenna can be made flexible. In this way, the magnetic field antenna can be attached to a curved surface.

As a modification of the first embodiment, the magnetic field antenna of the present invention may have only the core 1 in the shape shown in FIG. 1, and the insulator 3 and the metal plate 4 may have a sheet shape having a larger area than the core 1. In short, it is necessary that all parts of the core 1 do not protrude the insulator 3 and the metal plate 4.
The insulator 3 is necessary to prevent the coil from being short-circuited by the metal plate 4.

In order to cause the magnetic field antenna to resonate at a desired frequency, a capacitor is connected in parallel or in series with the coil.
FIG. 2 shows an example in which three coils wound around the straight portion of the core of FIG. 1 are connected in series, and a capacitor is connected in parallel between both ends (operates as parallel resonance). Alternatively, although not shown, a capacitor may be connected in parallel for each coil.
In addition, a capacitor may be inserted in series with a series-connected coil (operating as a series resonance).

FIG. 3 shows an example in which three coils wound around the straight portion of the core of FIG. 1 are connected in parallel, and capacitors are connected in parallel between both ends (operating as parallel resonance).
In addition, a capacitor may be inserted in series in each of the coils connected in parallel (operating as series resonance).

  Of course, the resonance may be performed by the inductance L of the coil instead of the capacitor.

  Further, when the magnetic field antenna of the present invention has a structure in which a magnetic material is attached to the lower side of the metal plate 4 (see FIG. 1) of the magnetic field antenna of the first embodiment, the frequency is moved by the object to which the magnetic field antenna is attached. There is no inconvenience.

  This magnetic material is also obtained by dispersing and solidifying a powdered magnetic material in a spherical, flat or crushed shape in a thermoplastic resin or thermosetting resin. The magnetic field antenna can be made flexible. In this way, the magnetic field antenna can be attached to a curved surface.

  In the first embodiment described above, the core 1 made of a magnetic material is composed of three straight portions and arranged at an angle of 120 ° to each other. This is the number of cores 1 forming the straight portions. By increasing the directivity of the magnetic field perpendicular to the surface of the metal plate 4 and reducing the side rope. Moreover, the angle which the core 1 of a linear part makes mutually does not matter.

  Using the magnetic field antenna described in the first embodiment, supplying the antenna output to the wireless system IC chip or supplying the output of the wireless system IC chip to the magnetic field antenna constitutes the wireless system of the present invention. it can.

  In addition, using the magnetic field antenna described in the first embodiment, the antenna output is supplied to the receiving circuit of the communication system, or the output of the transmitting circuit of the communication system is supplied to the magnetic field antenna to constitute the communication system of the present invention. be able to.

FIG. 4 shows a second embodiment of the magnetic field antenna of the present invention.
The embodiment shown in FIG. 4 also shows a case where a magnetic field antenna is formed by arranging cores wound with coils at respective straight portions on a metal surface through insulators at an angle of 120 ° to each other. Yes.
However, in this embodiment, as can be seen from the drawing, the core 1 made of a magnetic material is magnetically connected outside the three linear portions.

The advantage of this embodiment over the first embodiment is that the magnetic field does not leak outside the outer circle connecting the straight portions.
Also in FIG. 4 , 1 is a core made of a magnetic material, 2 is a coil (winding), 3 is an insulator, and 4 is a metal plate.

In this embodiment (Example 2), when the metal plate 4 of the magnetic field antenna further lower (see FIG. 4) (no insulating material 3 side) placing the magnetic substance by the subject matter pasting magnetic field antenna The inconvenience that the frequency moves is eliminated.

  Also in the second embodiment, all of the modifications described in the first embodiment and the wireless system and the communication system as applications thereof are possible, and thus the description thereof is omitted.

  The magnetic field antenna according to the present invention generates a magnetic field perpendicular to the metal surface and makes use of the characteristics of receiving and checking a wide range of visitors such as non-contact ticket gates for transportation, music halls, stadiums, entertainment venues, or IC tags Can be used for etc.

1 shows a first embodiment of a magnetic field antenna of the present invention. 3 shows an example in which three coils wound around a straight portion of the core of FIG. 1 are connected in series, and a capacitor is connected in parallel between both ends thereof. 3 shows an example in which three coils wound around a straight portion of the core of FIG. 1 are connected in parallel, and a capacitor is connected in parallel between both ends. 2 shows a second embodiment of the magnetic field antenna of the present invention. When a coil is arrange | positioned to a metal surface and the cross section of a coil is made to become perpendicular | vertical to a metal surface, it is a figure explaining that the magnetic field of an image is added and becomes 2 time (conventional figure). The example of arrangement | positioning of the sensor coil for generating the magnetic field of a direction perpendicular | vertical to a metal surface is shown (conventional figure). A case is shown in which two pairs of coils are arranged at an equal distance r from the center (conventional diagram).

Explanation of symbols

1 Core made of magnetic material 2 Coil 3 Insulator 4 Metal plate

Claims (8)

A magnetic field antenna for transmitting and receiving a magnetic field component, which has a plurality of linear portions each wound with a magnetic material having one end of the linear portions magnetically connected to each other through an insulator. together are arranged on the surface, the magnetic body is generated in a direction crossing said plurality of straight portions a magnetic field in the direction of canceling each other, and one of the straight portions is also not arranged on the extension of the other straight portion A magnetic antenna, wherein a magnetic material is further attached to a surface of the metal plate having the metal surface opposite to the metal surface .   2. The magnetic field antenna according to claim 1, wherein the windings of the respective linear portions are connected in series, and a resonance capacitor is connected in parallel between both ends of the series-connected windings or in series with the series-connected windings. A magnetic field antenna characterized by being connected.   2. The magnetic field antenna according to claim 1, wherein the windings of the straight portions are connected in parallel, and a resonance capacitor is connected in parallel between both ends of each winding for each winding, or in series with the winding for each winding. Magnetic field antenna characterized by being made. In the magnetic field antenna according to any one of claims 1 to 3, wherein the magnetic body, the magnetic field antenna, which is a metallic magnetic non magnetic ferrite or magnetic ferrite. In the magnetic field antenna according to any one of claims 1 to 3, wherein the magnetic body is spherical, flaky and any shape to the powdered with magnetic material thermoplastic resin or thermosetting of the crushed Magnetic field antenna characterized by being dispersed and solidified in a conductive resin. 2. The magnetic field antenna according to claim 1 , wherein an adhesive is applied to a surface of the magnetic material opposite to the surface on which the metal is applied, and the magnetic field antenna is attached to the object with the adhesive. Magnetic field antenna characterized by that. A magnetic body having a plurality of straight portions each wound with a winding and magnetically connected to one end of the straight portions is disposed on a metal surface via an insulator, and the magnetic body is A magnetic field in a direction that cancels each other is generated in a direction in which the plurality of linear portions intersect, and none of the linear portions is arranged on an extension line of the other linear portions, and the metal surface of the metal plate having the metal surface A wireless system IC chip is mounted between both ends of a magnetic field antenna whose magnetic material is further attached to the opposite surface or between both ends of each winding connected to each other or each winding. A featured wireless system. A magnetic body having a plurality of straight portions each wound with a winding and magnetically connected to one end of the straight portions is disposed on a metal surface via an insulator, and the magnetic body is A magnetic field in a direction that cancels each other is generated in a direction in which the plurality of linear portions intersect, and none of the linear portions is arranged on an extension line of the other linear portions, and the metal surface of the metal plate having the metal surface The transmission / reception circuit of the communication system is connected between both ends of the windings connected in series or both ends of each winding of the magnetic field antenna in which the magnetic material is further attached to the opposite surface. A featured communication system.

Images