JP2003018051A - Magnetic communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic communication device which is realized at a low cost and which needs only a small assembling space, when incorporating the device to an information terminal, such as a mobile phone with an azimuth sensor. SOLUTION: The magnetic communication device is provided with a magnetism detection circuit 30, in which a plurality of MI (magnetic sensor) elements 31 to 34 are sequentially placed in a loop and which supplies a high frequency current to the MI elements 31 to 34 for detecting magnetism; and changeover switches 55 to 58, 62, 63 which select a transmission coil mode, where the MI elements 31 to 34 are connected into a series circuit or an azimuth sensor more or a reception coil mode, where the series connection of the MI elements 31 to 34 is broken and each MI sensor is used as a discrete component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic communication device for transmitting a communication signal of a transmitting section as a magnetic field from a transmitting coil, and a receiving section for receiving the magnetic field by a receiving coil to process the communication signal. The invention is characterized in that the above-mentioned transmitting coil and receiving coil are combined by an MI element which is a magnetic sensor.

[0002]

2. Description of the Related Art FIG. 10 shows a basic configuration example of a magnetic communication device. As illustrated, the communication signal transmitted from the transmission / reception unit 10 is generated in the coil 11 of the transmission / reception unit 10 as a modulation magnetic field 12, and the magnetic field 12 is transmitted. The transmitter / receiver 20 receives the communication signal by the coil 21 that is electromagnetically induced by the magnetic field 12 and processes the signal.

The same applies to the case of transmitting from the transmitting / receiving section 20, and a communication signal is transmitted from the coil 21 as a modulated magnetic field and received by the coil 11 of the transmitting / receiving section 10. The coils 11 and 21 are adjacently arranged with a small interval.

The magnetic communication device as described above, which communicates by using a magnetic field as a transmission / reception medium, is provided in an IC card information reading device and the like as is widely known. Incorporation of technology is being actively developed.

Since the mobile phone has come to be used as a multifunctional information terminal as well as a dialog, it has many advantages by incorporating the above magnetic communication technology.

[0006] In addition, there is a portable telephone that can be used as an information terminal device in such a manner that a map can be read out and displayed on the display in addition to various kinds of information.

[0007]

When the magnetic communication technology is incorporated in a mobile phone, a special transmission / reception coil installation requires a special housing for installing this coil. Therefore, a space for incorporating the transmitter / receiver coil is required, which causes a problem in reducing the size and weight of the mobile phone.

On the other hand, such a mobile phone can read the map and know the current position, but since it has no direction sensor, it cannot know the direction from the current position. . Therefore, there is a demand for an azimuth sensor, but it is not yet provided from the viewpoint of reduction in size and weight.

In view of the above-mentioned circumstances, the present invention reduces the space for assembling the magnetic communication device and the azimuth sensor in an information terminal device such as a portable telephone, and reduces the cost as much as possible. It is an object of the present invention to provide a magnetic communication device adapted to the above.

[0010]

In order to achieve the above object, in the present invention, a plurality of MI elements are formed into a loop shape in a magnetic communication device having a transmitting coil and a receiving coil using a magnetic field as a transmitting and receiving medium. These MIs are arranged in sequence.
A magnetic detection unit configured to supply a high-frequency current to the element to detect the magnetic field and the plurality of MI elements described above are connected in series to form a series circuit body. A circuit switching means for forming the element as an individual circuit body, and the circuit switching means forms a series circuit body for a transmission / reception coil mode and an individual circuit body for a magnetic detection mode. A characteristic magnetic communication device is proposed.

The magnetic communication device having the above structure is
The MI elements arranged in a loop shape are connected in series by the circuit switching means, and a series coil of the MI elements forms a transmission coil or a reception coil. Thereby, a communication signal can be transmitted or received by these coils. When the serial circuit body of the MI element is used as the receiving coil in this way, in addition to receiving the communication signal as the electromagnetic induction coil, it is extracted as the impedance change component of the MI element and the change component is received as the communication signal. Can be configured as a receiving coil.

Further, a plurality of MI elements are formed as individual circuit bodies by circuit switching means to form a magnetically sensitive portion. This magnetically sensitive portion magnetically detects by supplying a high-frequency current to each MI element.

The above-mentioned magnetic communication device is constructed such that adjacent ends of the respective MI elements are connected to form a common end, and a switch means for forming the circuit switching means is provided at each common end. You can

Further, the above-mentioned magnetic communication device is constructed such that a circuit switching means forms a series circuit body to form a transmission coil mode, and an individual circuit body forms to switch between a magnetic detection mode and a reception coil mode. be able to.

A plurality of MI elements can be operated as a transmitting coil or a receiving coil by forming a series circuit body. However, compared to the loop coil which is a series circuit body, each MI element is an individual circuit. It is possible to improve the reception sensitivity. Therefore, it is advantageous to use a plurality of MI elements as individual circuits for magnetic detection and as receiving coils. As described above, when each MI element is used as the receiving coil, the impedance changing component of the MI element is extracted and the receiving coil receives the communication signal from the changing component.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of the arrangement configuration of MI elements for forming a magnetic detection unit that operates as an orientation sensor.

As shown in the figure, the magnetic detector 30 of this embodiment includes MI elements 31 and 32 arranged in parallel in a vertical direction.
The MI elements 33 and 34, which are arranged in parallel in the horizontal direction, are mounted on the substrate 35.
The film is formed on the plate surface of.

The MI element is a magnetic sensing element that utilizes a phenomenon (MI effect) in which the magnitude of the impedance is remarkably changed by the external magnetic field due to the skin effect when a high-frequency current is passed through the magnetic body.

FIG. 2 shows an example of the structure of a cross type MI element.
The main manufacturing method of this MI element is to form a thin film of a first magnetic body 41 on a plate surface of a substrate (for example, a glass substrate) 40, and then to form a second magnetic body on the upper surface of the first magnetic body 41. 42
Is formed into a thin film and then patterned by the photolitho method. The first and second magnetic bodies 41 and 42 can be made of a soft magnetic material such as an amorphous magnetic material, permalloy, or a microcrystalline material.

Further, in this MI element, the easy axis J of magnetization of the first magnetic body 41 is set with respect to the reference line Oo which is the direction of the current path.
With m1 set to an angle of α °, the easy magnetization axis J of the second magnetic body 42 is set.
It is a cross-type MI element in which m2 is provided at an angle of -α °.

The MI element thus constructed senses the external magnetic field Hex applied in the reference line Oo direction (longitudinal direction of the element) of the MI element by flowing the high frequency current Ipc. That is, the magnetization vector changes due to the external magnetic field Hex, and the magnetic permeability in the width direction of the element changes, so that the impedance changes.

Therefore, it can be configured as an azimuth detecting sensor which takes out the impedance change of the MI element as a detection voltage and obtains the azimuth by the detection voltage signal.

FIG. 3 is an MI characteristic diagram showing the voltage change rate with respect to the external magnetic field Hex of the cross type MI element shown in FIG. This MI characteristic diagram is a characteristic when measured by supplying a peak current of 40 mmA and a high frequency pulse current of frequency 10 MHz to the MI element, and E (millimeter V) on the vertical axis measures the output voltage of the MI element. It was done. In this characteristic diagram, the characteristic curve shown by the solid line is the MI characteristic when the external magnetic field Hex is changed from the negative side to the positive side, and the characteristic curve shown by the dotted line is that the external magnetic field Hex is changed from the positive side to the negative side. It is the MI characteristic when it is made to.

As shown in the figure, the impedance change of the above-mentioned crossover MI element has an MI characteristic showing a steep linearity in a predetermined range of the positive side magnetic field from the zero point (origin) of the magnetic field. Can be set as the detection range Hs.

On the other hand, geomagnetism is a low magnetic field in one direction in which the magnetic flux goes from the South Pole to the North Pole.
This MI is applied to the MI element as ex.
As can be seen from the above characteristic diagram, the element sensitively magnetically senses the low magnetic field and changes the impedance.

Therefore, if the geomagnetism detection voltage E corresponding to the impedance change is obtained and the azimuth is obtained from this detection voltage signal, the azimuth detection sensor can accurately indicate a predetermined azimuth.

M constituting the magnetic detection unit 30 of this embodiment
As the I elements 31 to 34, the cross MI elements described above are used, and each MI element forms a loop-shaped quadrilateral. The MI elements 31 to 34 are set to have a length of several mm to several tens of mm.

FIG. 4 is a block diagram showing the orientation sensor circuit. As shown, the output pulse current Ipc of the high frequency pulse oscillator 50 is supplied to the current limiting resistors 51a, 51b,
It supplies to each MI element 31-34 via 51c and 51d.

Therefore, a high-frequency pulse current Ipc flows through the MI elements 31 to 34, and the MI elements 31 to 3 are respectively supplied.
4 changes its impedance due to the magnetic field of the earth's magnetism, so that the high frequency pulse current modulated according to the changed impedance is output from each MI element 31-34.

The high-frequency pulse current thus output is detected by the detection / integration circuits 52a, 52b, 52c, 52d, the voltage signal corresponding to the impedance change of each MI element 31-34 is taken out, and this voltage is obtained. A change component of impedance is extracted by integrating.

Then, the output voltages of the detection / integration circuits 52a and 52b are differentially amplified by the differential amplifier 53 and output as the detection output PS1, and the detection / integration circuits 25c and 25c.
The output voltage of d is differentially amplified by the differential amplifier 54 and output as the detection output PS2.

For these detection outputs PS1 and PS2, the azimuth is obtained from the voltage value and its ratio. The MI elements 31 and 32,
The MI elements 33 and 34 are wired so as to react with magnetic fields from opposite directions with high sensitivity.

FIG. 5 shows a circuit example of a magnetic communication device in which a circuit changeover switch (circuit changeover means) is provided in the direction sensor circuit described above to operate as a transmitting coil and a receiving coil.

As shown in the figure, changeover switches 55, 56, 57 and 58 are provided in the power feeding paths of the MI elements 31 to 34. Then, the changeover switch 56 is connected to the transmitter 59 by the changeover, the changeover switch 57 is connected to the ground by the changeover, and the changeover switch 58 is changed by the change to M.
It has a configuration of a common terminal for connecting the I elements 31 and 34.

Further, in this circuit example, MI elements 31 and 3 are provided.
A connection circuit 60 for connecting 3 and a connection circuit 61 for connecting the MI elements 32, 34 are provided, and these connection circuits 60, 6 are provided.
Changeover switch 6 that grounds 1 as a common terminal
2, 63 are provided.

In the magnetic communication circuit thus constructed, when each of the change-over switches 55-58, 62, 63 is turned on to the a terminal, the individual circuit body of the MI element is formed and the direction sensor-
It becomes the operation mode.

Therefore, when the magnetic field from the transmission coil is received in this operation mode, the impedance of each of the MI elements 31 to 34 changes. Therefore, in the same manner as described above, the received signals from the differential amplifiers 53 and 54 are received. It is possible to output PR1 and PR2. In the operation mode of the azimuth sensor, the magnetic detector 30 detects geomagnetism with a constant low magnetic field, but since the magnetic field from the transmitting coil is a strong alternating magnetic field, it operates as a receiving coil.

Set the changeover switches 55-58, 62, 63 to b.
When it is put into the terminal, the MI elements 31 to 34 are connected in series to form a series circuit body of MI elements as shown in FIG. Therefore, a magnetic field is generated in the series circuit body including the MI elements 31 to 34 according to the communication signal output from the transmission unit 59, and the series circuit body is transmitted as a transmission coil.

FIG. 7 shows the positional relationship with the receiving coil 71 when the magnetic detector 30 is operated as a transmitting coil as described above. In addition, 70 is a transmitting / receiving unit
72 indicates a magnetic field. Further, in the drawing, the changeover switches 55 to 55
58 (58 is shown in a schematic diagram), 62 and 63 are omitted.

FIG. 8 shows an example of the structure of the magnetic detection section 80 in which the MI elements 31 to 34 are formed in a folded shape. Also in the magnetic detector 80 having the above-described configuration, the changeover switches 55 to 58, 62, and the like as in the magnetic communication circuit shown in FIG.
By providing 63 and the connection circuits 60 and 61, it is possible to operate as a transmission coil and a reception coil.

FIG. 9 shows an example of the structure of a magnetic detecting section 90 in which a connection circuit 60 for connecting the MI elements 31 and 33 and a connection circuit 61 for connecting the MI elements 32 and 34 are formed as patterns 91 and 92. The patterns 91 and 92 can be formed as the same film formation pattern as the MI element or as a conductor pattern different from the MI element. Furthermore, the changeover switch 55
˜58, 62, 63, the azimuth sensor circuit, and the magnetic communication circuit can also be formed on one substrate 93.

Although the preferred embodiment has been described above, the MI elements 31 to 34 may be connected in series to form a transmission coil, or may be operated as a reception coil by forming these series circuit bodies. In this case, in addition to the electromagnetic induction receiving coil, it can be configured as a receiving coil that extracts a communication signal as an impedance change component of the MI element.

Further, in the above-mentioned embodiment, the cross type MI is used.
Although each of the MI elements 31 to 34 is formed by using an element, the present invention can be implemented by using a normal MI element. However, since a normal MI element has impedance characteristics in which a positive magnetic field and a negative magnetic field are symmetrical, it is necessary to apply a bias magnetic field by a permanent magnet or an exciting coil.

[0044]

As described above, according to the present invention, a plurality of MIs are used.
Since the magnetic detection part of the magnetic sensor in which the elements are arranged in a loop is also used as the transmission coil and / or the reception coil of the magnetic communication, it is advantageous in reducing the cost of the magnetic communication device and is incorporated. Since the space is reduced, the magnetic communication device is extremely advantageous for reducing the size and weight of information terminals such as mobile phones.

[Brief description of drawings]

FIG. 1 is a perspective view showing an arrangement configuration example of MI elements forming a magnetic detection unit.

FIG. 2 is a partial perspective view showing a configuration example of a cross MI element.

FIG. 3 is an MI characteristic diagram showing a voltage change rate of an intersecting MI element with respect to an external magnetic field.

FIG. 4 is a block diagram showing a direction sensor-circuit.

FIG. 5 is a block diagram of a magnetic communication circuit shown as an embodiment of the present invention.

FIG. 6 is a simplified diagram showing a transmission coil mode of a magnetic detector.

FIG. 7 is a diagram showing a positional relationship with a receiving coil when the magnetic detecting unit is operated as a transmitting coil.

FIG. 8 is a perspective view showing a configuration example of a magnetic detection unit in which each MI element is formed in a folded shape.

FIG. 9 is a perspective view showing a configuration example of a magnetic detection section in which a connection section of adjacent MI elements is formed as a print pattern.

FIG. 10 is a diagram showing a basic configuration example of a magnetic communication device.

[Explanation of symbols]

30 Magnetic detector 31-34 MI element 35 substrate 50 high frequency pulse oscillator 52a to 52d Detection / integration circuit 53, 54 differential amplifier 55-58 Changeover switch 59 Transmitter 60, 61 Connection circuit 62, 63 selector switch

Continued front page    (72) Inventor Kazuhiko Ueno             2-9-13 Nakameguro, Meguro-ku, Tokyo Stanley             -Inside Electric Co., Ltd. (72) Inventor Takuya Kazama             2-9-13 Nakameguro, Meguro-ku, Tokyo Stanley             -Inside Electric Co., Ltd. F-term (reference) 5K012 AA01 AA05 AB03 BA04                 5K027 AA11 EE00

Claims (3)

[Claims] 1. In a magnetic communication device comprising a transmission coil and a reception coil, each of which uses a magnetic field as a transmission / reception medium, a plurality of MI elements are sequentially arranged in a loop and a high-frequency current is supplied to these MI elements. And a plurality of MI elements described above are connected in series to form a series circuit body, and the series connection is released to form a plurality of MI elements as individual circuit bodies. A magnetic communication device comprising circuit switching means, wherein the circuit switching means forms a series circuit body to form a transmission / reception coil mode and an individual circuit body forms a magnetic detection mode. 2. The magnetic communication device according to claim 1, wherein adjacent MI elements are connected at adjacent ends to form a common end, and the circuit switching means is formed at each common end. A magnetic communication device comprising: 3. The magnetic communication device according to claim 1, wherein the circuit switching means forms a series circuit body to form a transmission coil mode, and an individual circuit body forms to form a magnetic detection mode and a reception coil mode. A magnetic communication device characterized in that it is configured to switch to a mode.