JP2005056202A - Information processor, and antenna unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for evading the reduction of communicable distance when an antenna unit is covered by a conductive body such as metal, while suppressing the rise of a cost on the whole and the limitation of a degree of flexibility. <P>SOLUTION: When a current I<SB>1</SB>flows in a secondary coil 102 by allowing a current to flow in a first coil 101, an eddy current I<SB>2</SB>flows in a metal plate 201 in the opposite direction. A current I<SB>3</SB>flows in the opposite direction of the eddy current I<SB>2</SB>in a tertiary coil 103 by adjusting the capacitance of a capacitor Ck. Thus, a magnetic field to be generated by the eddy current I<SB>3</SB>is canceled by a magnetic field to be generated by the current I<SB>2</SB>flowing in the tertiary coil 103. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for performing contactless communication with an information recording medium incorporating an IC such as an IC card or an IC tag.

  In recent years, the introduction of contactless carrier systems capable of wirelessly contactlessly communicating with an information recording medium incorporating an IC has become popular. As a result, a traffic gate entrance / exit device and an entrance / exit room management device using an “IC card” with an IC built in the card, a logistics management device for managing an article by attaching an “IC tag” with an IC to the article, a wristwatch Non-contact type recording media of various sizes, such as an entrance / exit room management device using an “IC wristband” incorporating an IC, are used.

  A reader / writer device that is an information processing device that performs communication with such a non-contact type recording medium (hereinafter referred to as “IC media”) usually has a directivity loop so that the communication can be performed selectively. An antenna with a coil is adopted (mounted). As shown in FIG. 8, the loop coil constituting the antenna has a rectangular coil (a primary coil 801 connected to a signal processing circuit (not shown) and a secondary coil 802 electromagnetically coupled to the primary coil 801). It is usually wound in a loop. The secondary coil 802 is connected to the capacitor Cb.

  A conventional reader / writer device is electromagnetically coupled to an IC medium via an antenna as shown in FIG. 8 and supplies power. When a command is transmitted to the electromagnetically coupled IC media and a response is received from the IC media in response to the command transmission, communication with the IC media is started, and data is read from or written to the IC media. It is like that.

  Vending machines, transaction terminal devices, and the like in which the reader / writer device is incorporated are often composed of a metal casing. In the conductor such as metal, an eddy current is generated when the magnetic flux changes therein. The eddy current generated by the antenna magnetic field generates a magnetic field in the opposite direction to the magnetic field. For this reason, when a reader / writer device is incorporated in a housing such as metal (when the antenna is covered with a conductor such as metal), the magnetic field of the antenna is weakened due to the generation of eddy current, and the communicable distance is shortened. . In order to avoid this, conventionally, for example, as shown in FIG. 9, a ferromagnetic material 902 such as ferrite having a thickness of several millimeters is formed on an antenna substrate 901 on which a primary coil 801 and a secondary coil 802 are formed. The structure is in close contact.

  When the ferromagnetic body 902 is brought into close contact, most of the magnetic field generated from the antenna is distributed in the ferromagnetic body 902, so that the magnetic flux penetrating even if the metal is in the vicinity thereof is suppressed. As a result, the eddy current generated in the metal is suppressed, and the magnetic field generated from the antenna is prevented from being weakened. As a result, the decrease in the communicable distance is also suppressed. However, since the ferromagnetic material 902 has low mechanical strength and is difficult to handle (because vibration countermeasures are necessary), there is a problem that the overall cost greatly increases by providing it. .

  Conventionally, a method of cutting out a part of the metal used as the housing is also performed so that no eddy current flows (Patent Document 2). However, if this method is adopted, a part of the metal must be cut out, so that the degree of freedom as a device is limited. The manufacturing process of the apparatus incorporating the information processing apparatus becomes complicated. For this reason, it is considered important to avoid a decrease in the communicable distance while not only suppressing the cost but also limiting the degree of freedom.

  In addition, although the method of reducing the influence of another metal structure by attaching a metal plate to an antenna instead of the ferromagnetic body 901 is conventionally performed, the communicable distance is greatly reduced by this method. For this reason, it is not desirable to adopt that method.

JP 2002-123799 A JP 2001-338270 A

  An object of the present invention is to provide a technique for avoiding a decrease in the communicable distance when an antenna is covered with a conductor such as metal while suppressing an increase in overall cost and restriction on the degree of freedom.

  The information processing apparatus of the present invention is premised on performing non-contact communication with an information recording medium incorporating an IC via an antenna unit, and includes a loop-shaped loop coil that is electromagnetically coupled to the antenna unit. A resonance circuit is configured using a loop coil.

  The antenna unit preferably includes a primary coil connected to a communication circuit and a secondary coil that is electromagnetically coupled to the primary coil. Further, it is desirable that the loop coil is provided on a plane on which the primary coil and the secondary coil constituting the antenna unit are formed, or on a plane spaced apart in the direction perpendicular to the plane. When providing a loop coil on a plane that is spaced in the direction perpendicular to the plane on which the primary coil and the secondary coil forming the antenna unit are formed, the loop coil is attached to a conductor such as metal or the above It is desirable to realize this by providing it on a substrate on which a circuit is formed.

  The antenna unit of the present invention is based on the premise that the information processing apparatus is used for non-contact communication with an information recording medium incorporating an IC, and a primary coil to which a signal is supplied from the information processing apparatus, and the 1 A secondary coil that is electromagnetically coupled to the secondary coil; and a loop-shaped loop coil that is electromagnetically coupled to at least one of the primary coil and the secondary coil to form a resonance circuit.

  In the present invention, a loop-shaped loop coil that is electromagnetically coupled to an antenna unit is prepared, and a resonance circuit is configured using the loop coil. A magnetic field can be generated in the loop coil by the resonance circuit so as to cancel a magnetic field generated by an eddy current generated in a conductor such as a metal covering the loop coil by the magnetic field of the antenna unit. The need to employ a ferromagnetic material with low mechanical strength, such as ferrite, is avoided. For these reasons, it is possible to avoid a decrease in the communicable distance when covered with a conductor such as metal while suppressing an increase in overall cost and restriction on the degree of freedom.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram for explaining the configuration of an antenna unit mounted on an information processing apparatus (reader / writer apparatus) according to the present embodiment.

  As shown in FIG. 1, the antenna unit 100 is formed by forming a primary coil 101, a secondary coil 102, and a tertiary coil 103, each wound in a loop, on the same plane from the inside in that order. It is configured. The coils 101 to 103 are formed on the same plane by forming a pattern on an antenna substrate (not shown). The antenna unit 100 having such a configuration is one to which the present invention is applied, and the information processing apparatus according to the present embodiment is realized by mounting the antenna unit 100.

  The primary coil 101 is connected to a signal processing circuit mounted on the information processing apparatus. The signal processing circuit is for communicating with a non-contact type recording medium (IC medium) such as an IC card, an IC wristband, or an IC tag via the antenna unit 100, and generates a predetermined carrier signal. The signal is amplified to a predetermined voltage level and supplied to the primary coil 101 to generate a magnetic field.

  A plurality of wound secondary coils 102 are electromagnetically coupled to the primary coil 101, and are connected to a capacitor Cb. Thereby, the antenna unit 100 functions as an antenna in which a transformer is formed by the primary coil 101 and the secondary coil 102. The capacitance of the capacitor Cb is adjusted so that communication can be performed optimally when the antenna unit 100 is not covered with a conductor such as metal.

  The tertiary coil (loop coil) 103 is a coil electromagnetically coupled to the primary coil 101 and the secondary coil 102. A resonant circuit is configured by connecting a variable capacitor Ck.

  The antenna unit 100 having the above-described structure is a metal (conductor that is also a magnetic material) housing in which an information processing device (reader / writer device) on which the antenna unit 100 is mounted is incorporated in a vending machine or a transaction terminal device. It was produced assuming that it was covered with. Hereinafter, an operation (function) and a communicable distance when covered by such a case will be specifically described with reference to FIGS. 2 and 3.

  FIG. 2 is a diagram for explaining the current flowing through each part when a current is passed through the primary coil 101. Here, since the magnitude of the current flowing through the secondary coil 102 is several times larger than that of the primary coil 101, the illustration of the primary coil 101 is omitted, and only the secondary coil 102 is a coil that functions as an antenna. Show. The metal plate 201 is a part of the casing of the information processing apparatus or the casing of the apparatus incorporating the information processing apparatus.

Now, the current I ₁ of the secondary coil 102 flows in the direction shown in FIG. 2, the direction of the eddy current I ₂ flowing through the metal plate 201 is opposite to the current I ₁ as shown in FIG. From this, the capacitance of the capacitor Ck is adjusted so that the direction of the current I ₃ flowing through the tertiary coil 103 is opposite to the direction of the eddy current I ₂ flowing through the metal plate 201. By the adjustment, the magnetic field generated by the eddy current I ₃ can be canceled with the magnetic field generated by the current I ₂ flowing through the tertiary coil 103. Thereby, a decrease in the communicable distance can be suppressed.

  FIG. 3 is a diagram illustrating a measurement result of the communicable distance. For comparison, a measurement result obtained by using a conventional antenna unit (see FIG. 8; hereinafter referred to as “first conventional example” for convenience) when the metal plate 201 is not present is shown in FIG. Show. Similarly, the measurement result obtained using the conventional antenna unit when the metal plate 201 is present is shown in FIG. 9 (b), and the conventional antenna unit with the magnetic body 902 adhered as shown in FIG. (C) shows the measurement results obtained using the “second conventional example”. The measurement result obtained using the antenna unit 100 according to the present embodiment is shown in (d).

  As a matter of course, the primary coil and the secondary coil have the same shape, the number of turns, the material thereof, and the like, and current is supplied to the primary coil under the same conditions. In any case where the metal plate 201 exists, the distance from the antenna (primary coil, secondary coil) is constant (here, 20 mm). In this way, the communicable distance under the same conditions is measured.

  As shown in FIG. 3, in the first conventional example, if the metal plate 201 is not present, the communicable distance is 63 mm. However, if the metal plate 201 is present at a distance of 20 mm, the communicable distance is 38 mm. As a result, the communicable distance greatly decreases. In the second conventional example, the ferromagnetic material (for example, ferrite) 902 is brought into close contact, so that the communicable distance is maintained at 63 mm even when the metal plate 201 exists, and the reduction thereof is avoided. Similarly, in this embodiment, even if the metal plate 201 exists, a communicable distance of 63 mm can be secured. As can be seen from this, it is possible to avoid a decrease in the communicable distance.

  In the present embodiment, unlike the second conventional example, a ferromagnetic material such as ferrite does not have to be adhered to the antenna substrate or the like. For this reason, it is not necessary to take measures against vibrations in the information processing apparatus in which the antenna unit 100 is mounted or the apparatus in which the antenna unit 100 is incorporated. Thereby, compared with the 2nd prior art example, the fall of communicable distance can be avoided, reducing the whole cost sharply. Since the reduction of the communicable distance can be avoided even if the metal plate 201 exists, the restriction on the degree of freedom caused by the absence of the metal plate 201 is also avoided.

  The tertiary coil 103 and the capacitor Ck connected thereto can be manufactured by the same method as the secondary coil 102 and the capacitor Cb connected thereto. Thereby, when manufacturing the antenna unit 100, it is not necessary to use a different manufacturing process of different members and types. It is possible to avoid making the manufacturing process complicated on the information processing apparatus side on which it is mounted. For this reason, when the tertiary coil 103 and the capacitor Ck connected thereto are added to the antenna unit, they can be added more easily and at a lower cost. This is why the antenna unit 100 having them is manufactured.

  In the present embodiment, the tertiary coil 103 is arranged on the same plane as the primary coil 101 and the secondary coil 102, but this is not necessarily required. That is, for example, as shown in FIG. 4, the tertiary coil 103 is arranged on a plane different from those of the coils 101 and 102 (the plane at a position spaced in the direction orthogonal to the plane on which the coils 101 and 102 are formed). You may arrange | position on a parallel or substantially parallel plane.

  Such an arrangement may be realized by attaching the tertiary coil 103 to the metal plate 201 via a spacer 501 as shown in FIG. In that case, as the antenna unit 500, a conventional example as shown in FIG. 8, that is, an antenna unit in which a primary coil and a secondary coil are formed on an antenna substrate can be adopted.

  When the tertiary coil 103 is arranged on the same plane as the coils 101 and 102, the size of the antenna unit 100 must be made larger than that of the conventional antenna unit in order to maintain the communicable area. However, the tertiary coil 103 can be made the same size as the secondary coil 102 by arranging the tertiary coil 103 on a different plane. For this reason, an increase in the size of the antenna unit can be avoided, and an increase in the size of the information processing apparatus due to the increase in size can also be avoided.

  The signal processing circuit is usually mounted on a substrate on which a wide earth pattern is formed. Therefore, when the antenna unit is located in the vicinity of the antenna unit, the tertiary coil 103 is formed on the substrate 601 as shown in FIG. 6, and the antenna unit 500 shown in FIG. You may make it attach. As is apparent from these, the tertiary coil 103 can be arranged in various forms.

  The capacitor Ck connected to the tertiary coil 103 may be connected to the tertiary coil 103 via a lead wire 701 as shown in FIG. In such a case, the capacitor Ck can be disposed at a position where adjustment is easy. Thereby, adjustment can be easily performed. The number of turns of the tertiary coil 103 is 1 (see FIGS. 1, 4 and 6), but it may be 2 or more.

It is a figure explaining the structure of the antenna unit mounted in the information processing apparatus (reader / writer apparatus) by a present Example. It is a figure explaining the electric current which flows into each part when an electric current is sent through a primary coil. It is a figure which shows the measurement result of communicable distance. It is a figure explaining the other arrangement | positioning method of a tertiary coil. It is a figure explaining the specific example of the other arrangement | positioning method of a tertiary coil (the 1). It is a figure explaining the specific example of the other arrangement | positioning method of a tertiary coil (the 2). It is a figure explaining the other method of connecting a capacitor | condenser to a tertiary coil. It is a figure explaining the structure of the antenna unit mounted in the conventional information processing apparatus. It is a figure explaining the structure of the antenna unit mounted in the conventional information processing apparatus when conductors, such as a metal, exist.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Antenna unit 101 Primary coil 102 Secondary coil 103 Tertiary coil Ck Capacitor 201 Metal plate 501, 602 Spacer 601 Signal processing circuit board 701 Lead wire

Claims (6)

In an information processing apparatus that performs non-contact communication via an antenna unit with an information recording medium incorporating an IC,
A loop-shaped loop coil that is electromagnetically coupled to the antenna unit is provided, and a resonance circuit is configured using the loop coil.
An information processing apparatus characterized by that. The antenna unit has a primary coil connected to the communication circuit and a secondary coil electromagnetically coupled to the primary coil.
The information processing apparatus according to claim 1. The loop coil is provided on a plane on which a primary coil and a secondary coil constituting the antenna unit are formed, or on a plane spaced apart in a direction perpendicular to the plane.
The information processing apparatus according to claim 2. The loop coil is provided on a plane spaced apart in the vertical direction of the plane on which the primary coil and the secondary coil forming the antenna unit are formed by being attached to a conductor such as metal.
The information processing apparatus according to claim 3. The loop coil is provided on a substrate on which the circuit is formed, and is provided on a plane that is spaced apart in a direction perpendicular to the plane on which the primary coil and the secondary coil that form the antenna unit are formed. Yes,
The information processing apparatus according to claim 3. In an antenna unit used for non-contact communication between an information processing apparatus and an information recording medium containing an IC,
A primary coil to which a signal is supplied from the information processing device, and a secondary coil electromagnetically coupled to the primary coil;
A loop-shaped loop coil that is electromagnetically coupled to at least one of the primary coil and the secondary coil to form a resonant circuit;
An antenna unit comprising:

Images