JPH1062175A - Earth's magnetism direction sensor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify coil winding for excitation and to enable the increase of the number of the winding by forming notched parts on parts of a sensor board and providing ferromagnetic cores as separate bodies from the sensor board for the notched parts. SOLUTION: Rectangular notched parts are formed on a square sensor board 10. By this, ferromagnetic cores 1, 2, and 3 are given a form of a base, and the ferromagnetic cores are isolated into two ferromagnetic cores 4a and 4b in a form of a right angled isosceles triangle. Next, a pair of coil bobbins B1 and B2 on which coils C1 and C2 for excitation each are wound in advance are installed on the sensor board 10, and then a rectangular parallelopiped ferromagnetic core 4c is inserted between the ferromagnetic cores 4a and 4b. By this, a ferromagnetic core 4c formed as a separate body from the sensor board 10 is combined on the sensor board 10 that the ferromagnetic cores 1, 2, 3, 4a, and 4b are connected via a magnetic gap to form a closed circuit for focusing the earth's magnetism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a geomagnetic azimuth sensor for detecting azimuth of terrestrial magnetism by converging terrestrial magnetism with a ferromagnetic core and detecting the terrestrial magnetism using a magnetoresistance effect element.

[0002]

2. Description of the Related Art As a sensor for detecting the direction of geomagnetism,
A geomagnetic azimuth sensor has been proposed in which terrestrial magnetism is focused by a ferromagnetic core, detected by a plurality of magnetoresistive elements, and the azimuth of terrestrial magnetism is detected based on the magnetic field detected by each magnetoresistive element.

As shown in FIG. 10, this geomagnetic direction sensor has four ferromagnetic cores 10 made of ferrite or the like.
1, 102, 103, and 104 are provided with sensor substrates combined in a square shape so as to form magnetic gaps G1, G2, G3, and G4 having a predetermined width at 90 ° intervals. G1, G2, G3, G4
Are the magnetoresistive effect elements 111, 112, 1 respectively.
13, 114 are arranged.

[0004] The sensor substrate includes magnetic gaps G1, G
2, G3, and G4 are filled with a nonmagnetic material made of glass or the like, and the ferromagnetic cores 101, 102, and 10 are formed by these nonmagnetic materials so that the outer shape becomes square.
3,104 are connected. A closed magnetic path is formed by these ferromagnetic cores 101, 102, 103 and 104.

A magnetic gap G is provided on the sensor substrate.
1, G2, G3, G4, the magnetoresistive effect element 11
1, 112, 113 and 114 are formed, and
The ferromagnetic cores 101, 102, 103 and 104 are provided with magnetoresistive elements 111, 112, 113 and 114.
121, 122, and 12 for connecting the electrodes and external electrodes
3, 124, 125, 126, 127 and 128 are formed.

A square opening 120 is formed in the center of the sensor substrate to wind an exciting coil for applying a predetermined bias magnetic field to the magnetoresistive elements 111, 112, 113 and 114. Are formed. The ferromagnetic core 10 is passed through the opening 120.
Excitation coils 131 and 132 are wound around 1,103.

In the terrestrial magnetism sensor constructed as described above, the terrestrial magnetism is determined by the ferromagnetic cores 101, 102, and 10.
After being focused by 3 and 104, it is applied to the magnetoresistive elements 111, 112, 113 and 114. And
In this geomagnetic direction sensor, the exciting coils 131, 13
2, the magnetoresistive effect elements 111, 112, 113,
With the bias magnetic field applied to 114, the intensity of terrestrial magnetism applied to each of the magnetoresistive elements 111, 112, 113, 114 is detected. Then, the magnetoresistive element 1
The orientation of the geomagnetism is detected based on the magnitude of the geomagnetism in each direction detected by 11, 112, 113, and 114.

[0008]

By the way, in the above-mentioned geomagnetic direction sensor, the ferromagnetic core 1 constituting the sensor substrate is not required.
It is necessary to wind excitation coils 131 and 132 around 01 and 103. However, the exciting coil 13 is moved so as to pass through the opening of the sensor substrate having a square outer shape.
It is difficult to wind the coils 1 and 132, and a dedicated automatic winding machine is required to automatically wind the coils 131 and 132. In addition, if the excitation coils 131 and 132 are to be wound without using a dedicated automatic winding machine, the winding of the excitation coils 131 and 132 requires an extremely large number of man-hours. As described above, in the conventional geomagnetic direction sensor, it is difficult to wind the exciting coils 131 and 132 around the ferromagnetic cores 101 and 103 constituting the sensor substrate, which hinders cost reduction.

The exciting coils 131 and 132 are arranged so as to pass through openings of the sensor substrate having a square outer shape.
It is technically difficult to increase the number of turns when winding the coil. In the conventional geomagnetic direction sensor, the upper limit of the number of turns of the exciting coils 131 and 132 is about 100 turns. For this reason, in the conventional geomagnetic direction sensor, a bias magnetic field cannot be applied efficiently, and a large power is required for driving the sensor.

The present invention has been proposed in view of such a conventional situation, and a terrestrial magnetism sensor capable of easily winding an exciting coil and further increasing the number of windings. It is intended to provide.

[0011]

A terrestrial magnetism azimuth sensor according to the present invention, which has been completed to achieve the above object, comprises a sensor substrate having a plurality of ferromagnetic cores connected via a magnetic gap; A geomagnetic azimuth sensor having a magnetoresistive element disposed in a gap, wherein a notch is formed in a part of the sensor substrate, and the notch has a ferromagnetic core separate from the sensor substrate. Are arranged.

In the geomagnetic direction sensor according to the present invention, a cutout is formed in the sensor substrate, and a ferromagnetic core separate from the sensor substrate is arranged in the cutout.
Therefore, in this geomagnetic direction sensor, the exciting coil can be wound around the ferromagnetic core before the closed magnetic path is formed by the ferromagnetic core. That is, in this geomagnetic azimuth sensor, an exciting coil is wound around a sensor substrate having a notch formed thereon, and a ferromagnetic core separate from the sensor substrate is arranged in the notch, A closed magnetic path can be formed by the ferromagnetic core.

On the other hand, a method of manufacturing a geomagnetic azimuth sensor according to the present invention comprises the steps of: forming a notch in a sensor substrate in which a plurality of ferromagnetic cores are connected via a magnetic gap;
Attaching a coil bobbin around which a coil is wound to the sensor substrate so as to wind a ferromagnetic core constituting the sensor substrate having the cutout portion formed therein; And a step of disposing the ferromagnetic core.

In the method of manufacturing a geomagnetic bearing sensor according to the present invention, an exciting coil is wound around the ferromagnetic core before the closed magnetic circuit is formed by the ferromagnetic core. Therefore, in the method of manufacturing the geomagnetic direction sensor, the exciting coil can be easily wound around the ferromagnetic core.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the following examples, and it goes without saying that the shape, material, and the like can be arbitrarily changed without departing from the gist of the present invention.

First, a method of manufacturing the geomagnetic azimuth sensor according to the present embodiment will be described in detail.

When manufacturing the geomagnetic azimuth sensor according to the present embodiment, first, as shown in FIG. 1, four ferromagnetic cores 1, 2, 3, 4 each having a right-angled isosceles triangle shape are made of glass or the like. A sensor substrate 10 combined in a square shape is prepared via the non-magnetic material 5 described above. Here, each ferromagnetic core 1,
Since the non-magnetic material 5 is filled between 2, 3, and 4, a magnetic gap g1 is formed between the first ferromagnetic core 1 and the second ferromagnetic core 2, and the second ferromagnetic core 2 is formed. Ferromagnetic core 2
And a third ferromagnetic core 3, a magnetic gap g2 is formed between the third ferromagnetic core 3 and the fourth ferromagnetic core 4, and a magnetic gap g3 is formed between the third ferromagnetic core 4 and the fourth ferromagnetic core 4. A magnetic gap g4 is formed between the magnetic core 4 and the first ferromagnetic core 1.

In this sensor substrate 10, the magnetic gaps g1, g2, g3 and g4 are respectively provided with magnetoresistive elements M1, M2, M3 and M4 for detecting magnetic fields.
4 are formed in advance, and the ferromagnetic cores 1, 2, 2
The portions 3 and 4 include magnetoresistive elements M1, M2, M
3, eight electrodes a1, for connecting M4 to external electrodes
a2, a3, a4, a5, a6, a7, a8 are formed in advance. Although not shown, the sensor substrate 10 also includes a magnetoresistive element for temperature characteristic correction for correcting temperature characteristics such as a midpoint potential, etc.
2, M3, and M4.

Next, as shown in FIG. 2, the magnetic gaps g1, g2, g
3 and g4, the magnetoresistive elements M1 and M
2, M3, M4 and electrodes a1, a2, a3, a4, a5, a formed on the ferromagnetic cores 1, 2, 3, 4
A rectangular cutout K is formed so as not to interfere with 6, a7 and a8. Thereby, among the ferromagnetic cores 1, 2, 3, and 4 constituting the sensor substrate 10, the ferromagnetic cores 1, 2, and 3 are trapezoidal, and the ferromagnetic cores 4 are formed.
Is divided into two right-angled isosceles triangular ferromagnetic cores 4a and 4b. At this time, the width W and the depth D of the notch K are the shape of each of the trapezoidal ferromagnetic cores 1, 2 and 3 and the two ferromagnetic cores obtained by dividing the ferromagnetic core 4. As described later, the shape when a rectangular parallelepiped ferromagnetic core is inserted between the cores 4a and 4b is the same.
In addition, the bias magnetic field is set to be applied most efficiently to the magnetoresistive elements M1, M2, M3, and M4 formed in the magnetic gaps g1, g2, g3, and g4.

Next, as shown in FIG. 3, a pair of coil bobbins B1 and B2 on which the exciting coils C1 and C2 are respectively wound in advance are attached to the sensor substrate 10, and then the ferromagnetic core 4 is cut off. Two ferromagnetic cores 4a,
A rectangular parallelepiped ferromagnetic core 4c is inserted between the cores 4b.

Here, one coil bobbin B1 is arranged such that the exciting coil C1 wound around the coil bobbin B1 winds the ferromagnetic core 1 constituting the sensor substrate 10, and the other coil bobbin B2 Means that the exciting coil C2 wound around the coil bobbin B2 is
Are arranged so as to be wound.

The ferromagnetic core 4 is divided into two parts.
The shape of the rectangular parallelepiped ferromagnetic core 4c inserted between the two ferromagnetic cores 4a and 4b is the shape when the ferromagnetic core 4 is combined with the two divided ferromagnetic cores 4a and 4b. However, the shape is substantially the same as the shape of the other trapezoidal ferromagnetic cores 1, 2, 3.

According to the above steps, as shown in FIG. 4, a trapezoidal ferromagnetic core 1 having a coil bobbin B1 around which an exciting coil C1 is wound, a trapezoidal ferromagnetic core 2, A trapezoidal ferromagnetic core 3 to which a coil bobbin B2 around which an exciting coil C2 is wound is attached, and two right-angled isosceles triangular ferromagnetic cores 4a and 4b.
A rectangular parallelepiped ferromagnetic core 4c formed separately from the sensor substrate 10 is combined with the sensor substrate 10 connected through the magnetic gaps g1, g2, g3, and g4 to converge geomagnetism. A closed magnetic path is formed, and the geomagnetic direction sensor is completed.

In this geomagnetic azimuth sensor, when a rectangular parallelepiped ferromagnetic core 4c is inserted between two ferromagnetic cores 4a and 4b obtained by separating the ferromagnetic core 4, the Cores 4a and 4b and ferromagnetic core 4
There is a slight gap between c. However, if the gap is too large, the output obtained from the geomagnetic azimuth sensor decreases, and the azimuth angle detection accuracy deteriorates.

Therefore, the relationship between the size of the air gap generated between the ferromagnetic cores 4a and 4b and the ferromagnetic core 4c and the output from the geomagnetic azimuth sensor was examined. FIG. 5 shows the results. In FIG. 5, the vertical axis represents the output from the geomagnetic direction sensor, and the horizontal axis represents the ferromagnetic core 4a and the ferromagnetic core 4c.
Between the ferromagnetic core 4c and the ferromagnetic core 4c.
This is the sum with the gap t2 between b.

As can be seen from FIG. 5, as the air gap between the ferromagnetic cores 4a and 4b and the ferromagnetic core 4c increases, the output from the geomagnetic direction sensor decreases. In particular, when the gap between the ferromagnetic cores 4a and 4b and the ferromagnetic core 4c exceeds 30 μm, the output from the geomagnetic azimuth sensor is significantly reduced. Therefore, the ferromagnetic core 4
It is preferable that the gap between the a and 4b and the ferromagnetic core 4c be smaller, specifically, it is preferable that the gap be 30 μm or less.

In the above-described geomagnetic direction sensor according to the present embodiment, the coil bobbin on which the exciting coil is wound is attached to the sensor substrate before the ferromagnetic core is completely assembled. Therefore, in the present embodiment,
The winding of the exciting coil is very easy.

Further, since it is very easy to increase the number of turns of the coil around the coil bobbin, the number of turns of the exciting coil is reduced by attaching the coil bobbin on which the exciting coil is wound to the ferromagnetic core. Very much can easily be done. In addition, since the winding of the coil on the coil bobbin can be performed using a general-purpose automatic winding machine, the winding of the exciting coil can be easily automated.

Next, the above-described geomagnetic azimuth sensor will be described in more detail with reference to FIG. 6, which schematically shows a circuit configuration.

As shown in FIG. 6, the geomagnetic direction sensor has magnetic gaps g1, g2, g3, g4 at 90-degree intervals.
Are formed so that the four ferromagnetic cores 1, 2, 3,
4 and the magnetic gap g
The magnetoresistive elements M1, M2, M3, and M4 for detecting the terrestrial magnetism are arranged in 1, g2, g3, and g4, respectively. One of the four ferromagnetic cores 1, 2, 3, 4 is, as described above, one of the two ferromagnetic cores 4 a separated by forming the cutout K in the sensor substrate 10. , 4b, and a rectangular parallelepiped ferromagnetic core 4c formed separately from the sensor substrate 10.

Suitable materials for the ferromagnetic cores 1, 2, 3, and 4 are those having excellent soft magnetic properties, such as permalloy, sendust, amorphous, and ferrite. Further, the magnetoresistive elements M1, M2, M3, M
4 is a soft magnetic material exhibiting a magnetoresistive effect, specifically,
A Ni-Fe alloy, a Co-Ni-Fe alloy, or a soft magnetic material obtained by adding a small additive to these alloys is used.

The magnetoresistance effect elements M1, M2, M3
M4 includes two magnetoresistive elements M1 and M3 for detecting a magnetic field in the X-axis direction, and two magnetoresistive elements M2 and M2 for detecting a magnetic field in the Y-axis direction orthogonal to the X-axis direction.
M4. These magnetoresistive elements M1, M2, M3, and M4 are connected to a constant potential power supply Vcc, and a sense current is supplied from the constant potential power supply Vcc to these magnetoresistive elements M1, M2, M3, and M4. Is supplied.

On the other hand, exciting coils C1 and C2 are wound around the ferromagnetic cores 1 and 3, respectively, and an AC bias current IB is supplied to the exciting coils C1 and C2 to thereby produce magnetic gaps g1 and C1. A bias magnetic field is applied to the magnetoresistive elements M1, M2, M3, and M4 disposed in g2, g3, and g4. That is, the exciting coils C1, C2
Are supplied to the magnetoresistive elements M1 and M2 for detecting the magnetic field in the X-axis direction by the AC bias current IB supplied to
Bias magnetic fields in directions opposite to each other are applied to the magnetoresistive elements M2 and M4 for detecting a magnetic field in the Y-axis direction, respectively.

Each of the magnetoresistive elements M1, M2, M
Reference numerals 3 and M4 denote temperature characteristic correction magnetoresistive elements M5, M6, M7, and M for correcting temperature characteristics such as a midpoint potential.
8 are connected. That is, the magnetoresistance effect element M1
Is connected to a magnetoresistive element M5 for correcting temperature characteristics, a magnetoresistive element M2 is connected to a magnetoresistive element M6 for correcting temperature characteristics, and a magnetoresistive element M3 is connected to a magnetoresistive element M3 for correcting temperature characteristics. The resistance effect element M7 is connected,
The magnetoresistive element M4 is connected to a magnetoresistive element M8 for temperature characteristic correction.

Here, the magnetoresistive elements M5, M6, M7, M8 for temperature characteristic correction are composed of ferromagnetic cores 1, 2,
The elements are arranged orthogonal to the magnetoresistive elements M1, M2, M3, and M4, respectively, so as to be parallel to the magnetic flux passing through the elements 3 and 4. That is, the magnetoresistive element M5 for temperature characteristic correction is disposed outside the magnetic gap g1 so as to be orthogonal to the magnetoresistive element M1. Outside, it is arranged orthogonal to the magnetoresistive element M2, and the magnetoresistive element M7 for temperature characteristic correction is arranged outside the magnetic gap g3 so as to be orthogonal to the magnetoresistive element M3. The temperature characteristic correcting magneto-resistance effect element M8 is disposed outside the magnetic gap g4 so as to be orthogonal to the magneto-resistance effect element M4.

FIG. 7 shows an equivalent circuit of the geomagnetic azimuth sensor having the above configuration. That is, in this geomagnetic direction sensor, the two magnetoresistive elements M1 and M3 for detecting the magnetic field in the X-axis direction constitute a bridge together with the magnetoresistive elements M5 and M7 for temperature characteristic correction. Is supplied with a sense current from a constant potential power supply Vcc. The output from the bridge is fed to a differential amplifier A1, the differential by the differential amplifier A1 is taken, as a result, differential indicating the size of the X-axis direction of the magnetic field component of the external magnetic field H _E A signal (X output) is output. In this case, the excitation coil C1, C2, the magnetoresistive element M1 is applied bias magnetic field H _B, the magnetoresistive element M3, compared bias magnetic field H _B applied to the magnetoresistance effect element M1 Bias magnetic field −H _B having a different azimuth by 180 degrees is applied.

Similarly, the two magnetoresistive elements M2 and M4 for detecting the magnetic field in the Y-axis direction also constitute a bridge together with the magnetoresistive elements M6 and M8 for temperature characteristic correction. A sense current is supplied from potential power supply Vcc. The output from the bridge is fed to a differential amplifier A2, the differential by the differential amplifier A2 is taken, as a result, differential indicating the magnitude of the magnetic field component in the Y-axis direction of the external magnetic field H _E A signal (Y output) is output. In this case, the excitation coil C1, C2, the magnetoresistive element M2, is applied bias magnetic field H _B, the magnetoresistive element M4, relative to the bias magnetic field H _B applied to the magnetoresistance effect element M2 Bias magnetic field −H _B having a different azimuth by 180 degrees is applied.

The magnetoresistive elements M1, M2, M3, M4 used in the above-described geomagnetic direction sensor have the following features.

(1) The resistance value changes according to the strength of the magnetic field.

(2) The ability to sense a weak magnetic field is excellent.

(3) The change in resistance can be extracted as an electric signal.

The terrestrial magnetism sensor detects the azimuth of the terrestrial magnetism by converting a magnetic signal due to the terrestrial magnetism into an electric signal by utilizing the characteristics of the magnetoresistance effect element.

Hereinafter, the principle of magnetic field detection by such a magnetoresistive element will be described with reference to a magnetoresistance curve shown in FIG.

In FIG. 8, the horizontal axis indicates the magnetic field H applied to the magnetoresistive element perpendicularly, and the vertical axis indicates the resistance value R of the magnetoresistive element. Here, since the vertical axis indicates the resistance value of the magnetoresistive element, the value of the vertical axis corresponds to the output voltage when a direct current is applied to the magnetoresistive element.

As shown in FIG. 8, the resistance value R of the magnetoresistive element is maximum when the magnetic field H is zero, and when a large magnetic field H is applied, specifically, the pattern R of the magnetoresistive element is When a magnetic field H of about 100 to 200 gauss is applied, it is reduced by about 3% depending on the shape and the like. Therefore, in the geomagnetic azimuth sensor, a change in the magnetic field H is detected as a change in the resistance value R by the magnetoresistance effect element having such characteristics.

As described above, the AC bias current I is applied to the exciting coils C1 and C2.
By flowing B, an AC bias magnetic field is applied. By applying the bias magnetic field in this manner, it is possible to use a portion where the slope of the magnetoresistive curve is large for detecting an external magnetic field, and to set the S / N of the output from the magnetoresistive element, ie, the amplitude of the output voltage. The improvement and the distortion rate are achieved.

Here, as described above, the bias magnetic field H _B is applied to the magnetoresistive element M1 of the magnetoresistive elements M1 and M3 for detecting the magnetic field in the X-axis direction, as described above. the magnetoresistive element M3 is 180-degree direction with respect to the bias magnetic field H _B applied to the magnetoresistance effect element M1 is different bias magnetic field -H _B is applied. Similarly, of the Y-axis direction of the magnetoresistive element M2, for detecting a magnetic field M4, is applied bias magnetic field H _B is the magnetoresistive element M2, the magnetoresistive element M4, the magnetoresistive element Bias magnetic field H applied to M2
_A bias magnetic field −H _B having a 180 ° azimuth different from _B is applied.

[0048] At this time, the incoming magnetic field H _E by geomagnetism, for example, a magnetic field applied to the magnetoresistive element M1, M3 for detecting the magnetic field in the X axis direction, the magnetic field applied to the magneto-resistance effect element M1 (H _B + H _E), and the magnetic field applied to the magnetoresistive element M3 is (-H _B + H _E).

At this time, since the AC bias magnetic field H _B is applied to the magneto-resistance effect element M1, the magnetic field applied to the magneto-resistance effect element M1 changes as shown by a solid line A in FIG. This change in the magnetic field is output as a voltage change as shown by a solid line B in FIG. On the other hand, since the AC bias magnetic field −H _B is applied to the magnetoresistive element M3, the magnetic field applied to the magnetoresistive element M3 changes as shown by a solid line C in FIG. The change is output as a voltage change as shown by a solid line D in FIG.

The difference L between the output from the magnetoresistive element M1 as shown by the solid line B in FIG. 8 and the output from the magnetoresistive element M3 as shown by the solid line D in FIG. The differential signal for the magnetic field in the X-axis direction, that is, an X output is taken out by the dynamic amplifier A1. Similarly, a change in the magnetic field is output as a voltage change from the magnetoresistive elements M2 and M3 for detecting the magnetic field in the Y-axis direction, and a differential signal for the magnetic field in the Y-axis direction, ie, Y The output is retrieved.

[0051] Then, these differential signals are changed by the orientation of the geomagnetism H _E, respectively H _E sinθ, H _E co
It is proportional to sθ. Therefore, when the azimuth θ of the geomagnetism is plotted on the horizontal axis and the voltages of the X output and the Y output are plotted, the results are as shown in FIG. Therefore, the azimuth θ of the geomagnetism can be calculated from the X output that is a differential signal for the magnetic field in the X-axis direction and the Y output that is a differential signal for the magnetic field in the Y-axis direction.

That is, the ratio between the X output and the Y output V _x / V _y
It is these outputs H _E sin [theta respectively, H _E cos
Since it is proportional to θ, as shown in the following equation (1), t
can be represented by anθ.

V _x / V _y = sin θ / cos θ = tan θ (1) Accordingly, the azimuth θ of the geomagnetism is represented by the following equation (2).

Θ = tan ⁻¹ (V _x / V _y ) (2) In the above equation (2), when V _x ≧ 0, 0
° ≦ θ ≦ 180 °, and when V _x <0, 180 °
<Θ <360 °.

[0055] As described above, the geomagnetic direction sensor according to the present embodiment, it is possible to know the azimuth θ of the geomagnetism H _E.

[0056]

As is apparent from the above description, in the present invention, a notch is formed in the sensor substrate, and a ferromagnetic core separate from the sensor substrate is arranged in the notch. Therefore, the exciting coil can be wound around the ferromagnetic core before the closed magnetic path is formed by the ferromagnetic core. Therefore, according to the present invention, the exciting coil can be easily formed on the ferromagnetic core, and as a result, the cost required for manufacturing the geomagnetic azimuth sensor can be reduced.

By mounting a coil bobbin on which a coil is wound in advance on a ferromagnetic core,
It is possible to easily increase the number of windings of the exciting coil. By increasing the number of windings of the exciting coil, it is possible to obtain a small-sized geomagnetic azimuth sensor having low power consumption.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a sensor substrate to which four ferromagnetic cores are connected.

FIG. 2 is a perspective view showing a state in which a cutout portion is formed in the sensor substrate shown in FIG.

FIG. 3 illustrates a sensor substrate having a cutout formed therein.
It is a perspective view which shows a mode that a coil bobbin is attached and a ferromagnetic core separate from a sensor board is attached.

FIG. 4 is a perspective view showing a configuration example of a geomagnetic direction sensor to which the present invention is applied.

FIG. 5 is a diagram showing a result of measuring a relationship between an output from a geomagnetic direction sensor and a gap between ferromagnetic cores.

FIG. 6 is a diagram schematically illustrating a circuit configuration of the geomagnetic bearing sensor illustrated in FIG. 4;

7 is a circuit diagram showing an equivalent circuit of the geomagnetic direction sensor shown in FIG.

FIG. 8 is a diagram for explaining the principle of magnetic field detection by a magnetoresistive element.

FIG. 9 is a diagram illustrating a relationship between an output voltage V and a azimuth θ of geomagnetism.

FIG. 10 is a perspective view showing a configuration example of a conventional geomagnetic direction sensor.

[Explanation of symbols]

1,2,3,4,4a, 4b, 4c ferromagnetic core,
10 sensor substrate, g1, g2, g3, g4 magnetic gap, M1, M2, M3, M4 magnetoresistive element,
C1, C2 excitation coil, B1, B2 coil bobbin

Claims (5)

[Claims] 1. A geomagnetic azimuth sensor comprising: a sensor substrate in which a plurality of ferromagnetic cores are connected via a magnetic gap; and a magnetoresistive element disposed in the magnetic gap. A geomagnetic azimuth sensor, wherein a notch portion is formed in the portion, and a ferromagnetic core separate from the sensor substrate is disposed in the notch portion. 2. The notch is formed in a ferromagnetic core constituting the sensor substrate, and the notch is formed in the ferromagnetic core having the notch and the notch in the sensor substrate. 2. The geomagnetic direction sensor according to claim 1, wherein a gap between the ferromagnetic core and the ferromagnetic core is 30 μm or less. 3. The magnetic sensor according to claim 1, wherein the coil bobbin around which the coil is wound is arranged such that the coil winds around a ferromagnetic core constituting the sensor substrate. 4. A step of forming a notch in a sensor substrate in which a plurality of ferromagnetic cores are connected via a magnetic gap, and a step of forming a notch in the sensor substrate in which the notch is formed. A step of attaching a coil bobbin around which a coil is wound to the sensor substrate so as to be wound, and a step of disposing a ferromagnetic core separate from the sensor substrate in the cutout portion. A method for manufacturing a geomagnetic direction sensor. 5. When disposing a ferromagnetic core separate from the sensor substrate in the notch portion, the ferromagnetic core constituting the sensor substrate having the notch portion is disposed in the notch portion. 5. The method for manufacturing a geomagnetic bearing sensor according to claim 4, wherein a gap between the ferromagnetic core and the ferromagnetic core is 30 μm or less.