JPH09145374A - Geomagnetic bearing sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to reduce in size the geomagnetic bearing sensor by forming the shapes of the opposed surfaces of a ferromagnetic core in tapered state, thereby maintaining the bearing accuracy high. SOLUTION: Ferromagnetic units K1 , K2 are formed on a flattened layer 5. The upper conductor layer 7 is connected at the ends to the one front and the other rear end of the adjacent lower conductor layer 3, the layer 7 is integrated with the layer 3 to integrally form an exciting coil. The shapes of the opposed surfaces (a) of the cores K1 , K2 opposed to a gap G1 near the ends are so formed in tapered states that the thicknesses are reduced toward the ends. The magnetic flux amount to be introduced into an MR sensor (magnetorsistance effect element) M1 disposed in the gap G1 of the magnetic flux generated in the gap G1 from the cores K1 , K2 for converging the geomagnetism is increased and concentrated at the sensor M1 . Accordingly, the sensor can be reduced in size with high accuracy, and the geomagnetism is efficiently supplied as a magnetic signal to the sensor M1 to obtain the high bearing accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a geomagnetic direction sensor using a magnetoresistive effect element, and more particularly to a novel geomagnetic direction sensor combined with a ferromagnetic core for high sensitivity.

[0002]

2. Description of the Related Art For example, in a color cathode ray tube, the trajectory of an electron beam emitted from an electron gun may be bent by geomagnetism, and the beam arrival position (landing) on the fluorescent screen may change. Especially in high definition cathode ray tubes,
Since the landing margin is small, the landing change (positional deviation) causes a problem such as deterioration of color purity.

To correct this, a landing correction coil is usually attached to the cathode ray tube, and an optimum current necessary for landing correction is automatically supplied to the landing correction coil according to the direction of the earth's magnetism.
The trajectory of the electron beam is controlled to prevent mislanding.

Therefore, in the landing correction, it is necessary to accurately detect the azimuth of the geomagnetism, and a so-called geomagnetic azimuth sensor is used.

Alternatively, as an alternative to the conventionally used magnet type compass (magnetic compass), a geomagnetic compass sensor is also used as a portable compass.

As described above, the geomagnetic direction sensor is used for various purposes, and its typical structure is known as a so-called fluxgate type or magnetoresistive type (MR type). Has been.

As shown in FIG. 12, the fluxgate type geomagnetic direction sensor comprises a permalloy core 101 around which an electric signal output coil 102 and an excitation coil 103 are wound, and the geomagnetism is focused by the permalloy core. ,
The structure is such that this is transmitted to the electric signal output coil 102.

In this fluxgate type geomagnetic direction sensor, the exciting coil 103 generates an AC bias magnetic field H _B in the permalloy core 101, and a pulsed voltage generated when the bias magnetic field is reversed is detected as a signal. To do. Since the voltage value of this pulsed voltage changes depending on the direction of the geomagnetism, it can be used as a geomagnetic sensor.

However, since this fluxgate type geomagnetic direction sensor converts the geomagnetism into an electric signal by means of a coil, the number of windings of the electric signal output coil 102 is extremely increased and the focusing effect is obtained in order to increase the sensitivity. The shape of the permalloy core 101 needs to be increased in order to increase the height. Therefore, it is difficult to reduce the size and price.

On the other hand, the MR type geomagnetic direction sensor is shown in FIG.
As shown in FIG. 3, a magnetoresistive effect element (MR sensor) 11
The MR sensor chip 110 including the
4 for these MR sensor chips 110
An AC bias magnetic field H _B in the 5 ° direction is applied. The equivalent circuit is shown in FIG. When used as the geomagnetic direction sensor, one set having the structure shown in FIG. 13 is used so that the winding directions of the air-core coils are orthogonal to each other.

Since this MR type geomagnetic direction sensor uses a magnetoresistive effect element, the MR type geomagnetic direction sensor has higher sensitivity than the fluxgate type geomagnetic direction sensor, but the MR sensor chip 110 alone senses the geomagnetism. Therefore, it is insufficient to detect the orientation of the geomagnetism of about 0.3 Gauss.

Further, in this MR type geomagnetic direction sensor, a bias magnetic field H _{B in the} direction of 45 ° is applied to the MR sensor chip 110, and the MR sensor chip 110 has an MR for improving sensitivity.
Since the curve is forced to be steep, the MR characteristic has hysteresis, and in order to eliminate this, the signal processing circuit becomes complicated and the azimuth accuracy is ±
It has inconvenience such as 10 degrees.

[0013]

As described above, the conventionally known geomagnetic direction sensor remains unsatisfactory in terms of sensitivity, and it is difficult to reduce its size and cost.

Therefore, the present invention has been proposed in view of such conventional circumstances, and provides a geomagnetic direction sensor having practical sensitivity and high azimuth accuracy and capable of miniaturization and fineness. With the goal.

[0015]

The geomagnetic direction sensor of the present invention converts the geomagnetism into a large magnetic flux density by concentrating the geomagnetism with a ferromagnetic core, and arranges this in the gap between the cores. (Hereinafter, simply referred to as MR sensor).

The geomagnetic direction sensor of the present invention includes a plurality of ferromagnetic cores arranged in the circumferential direction with a predetermined gap for focusing the geomagnetism, and a plurality of ferromagnetic cores in the gap so as to be substantially orthogonal to the magnetic field direction in the gap. Arranged M
An R sensor and an exciting coil wound around the ferromagnetic core to apply a bias magnetic field to the MR sensor by supplying a bias current, and the ferromagnetic core, the MR sensor and the exciting coil are thin films. It is formed on the substrate by a forming technique, and is formed such that the vicinity of the end of each ferromagnetic core facing the gap is gradually reduced in film thickness toward the end.

Here, as the shape of the vicinity of the end portion, it is preferable to form not only the inclined surface but also a stepped shape having a step with a ferromagnetic core having a two-layer structure, or an arc shape. Is.

In this case, it is preferable to form the ferromagnetic core, the MR sensor, the exciting coil, and the interlayer insulating layer by a thin film forming technique including a thin film forming process (vacuum vapor deposition, sputtering, etc.) and a photo etching process. Is.

A bias magnetic field H _B is generated by supplying a bias current I _B to an exciting coil wound around a ferromagnetic core, so that the MR sensor has high magnetic field sensitivity and good linearity. use. In addition,
The bias current I _B may be an alternating current or a direct current.

When the MR sensor is used with an AC bias, the azimuth signal (low frequency) can be taken out as an electric signal superimposed on the AC signal (high frequency).
Noise components such as offset and temperature drift generated by the R sensor can be removed by circuit processing by a high-pass filter (HPF) or the like, and high azimuth accuracy can be obtained.

In the present invention, since the MR sensor obtains outputs in the X-axis direction and the Y-axis direction which are orthogonal to each other,
Films are formed at least at two positions so as to be orthogonal to each other. Preferably, four MR sensors are deposited at equal angular intervals (90 ° intervals).

On the other hand, the ferromagnetic core is formed in the circumferential direction so as to have gaps at equal angular intervals (for example, 90 ° intervals) according to the arrangement of the MR sensor and to form a closed magnetic path. At this time, the ferromagnetic cores are preferably arranged in a symmetrical structure even when rotated by 90 °. Specifically, the films are formed in a square shape or an annular shape.

A soft magnetic material (so-called soft material) such as permalloy having a high magnetic permeability and a high saturation magnetic flux density is used for the ferromagnetic core, and is used for applying a bias magnetic field and focusing the earth's magnetism.

In the geomagnetic direction sensor of the present invention, the ferromagnetic core constitutes the magnetic path of the bias magnetic field, and
It functions as a so-called focusing horn that focuses the earth's magnetism.
As a result, the total amount of geomagnetism applied to the MR sensors orthogonal to each other is determined according to the angle formed by the geomagnetism and the MR sensor, respectively, and is perpendicular to the geomagnetic line passing through the center of the closed magnetic circuit formed by the ferromagnetic core from each MR sensor. Proportional to the line drawn.

Further, in the above geomagnetic direction sensor, the ferromagnetic core, the MR sensor, the exciting coil, and the interlayer insulating layer are formed on the substrate by the thin film forming technique. In this case, for example, as compared with an MR sensor formed on a substrate, a geomagnetic direction sensor manufactured by combining a bulk portion in which a ferromagnetic core is wound and an exciting coil is wound, There are few adjustment points and the operating characteristics are extremely stable.

In addition to that, in the geomagnetic direction sensor, since the thickness of the ferromagnetic cores forming the gaps is formed in the vicinity of the ends so that the film thickness gradually decreases toward the ends. Of the magnetic flux generated in the gap from the ferromagnetic core focusing the geomagnetism, the amount of magnetic flux entering the MR sensor arranged in the gap increases and this MR
Focus on the sensor. Therefore, the efficiency of applying the magnetic flux to the MR sensor of the ferromagnetic core is significantly improved.

Therefore, the geomagnetic direction sensor can be miniaturized with high accuracy, and the geomagnetism can be efficiently supplied to the MR sensor as a magnetic signal to obtain high direction accuracy.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described in detail below with reference to the drawings.

FIG. 1 shows an example of the basic structure of a geomagnetic direction sensor to which the present invention is applied. In the geomagnetic direction sensor of this embodiment, four arc-shaped ferromagnetic cores K ₁ , K ₂ , K ₃ , K ₄ made of a soft magnetic material such as permalloy are combined in an annular shape, and a gap G _{1 is formed} at 90 ° intervals. , G ₂ , G ₃ ,
G ₄ is formed so that the MR sensors M ₁ and G ₁ are respectively placed in the gaps G ₁ , G ₂ , G ₃ and G ₄ .
It is formed by arranging M ₂ , M ₃ and M ₄ .

The respective ferromagnetic cores K ₁ , K ₂ , K ₃ , K
₄ are excitation coils C ₁ , C ₂ , C ₃ , C _{4 respectively.}
So that the bias magnetic field H _B is applied to the MR sensors M ₁ , M ₂ , M ₃ and M ₄ arranged in the gaps G ₁ , G ₂ , G ₃ and G ₄ at a substantially right angle. Is formed in. The MR sensors M ₁ , M ₂ , M ₃ and M ₄ are
The film is formed in each of the gaps G ₁ , G ₂ , G ₃ , and G ₄ , and therefore each MR sensor M ₁ , M ₂ ,
Bias magnetic field H _B almost parallel to the film surfaces of M ₃ and M ₄
Is applied.

In particular, in the present embodiment, Si,
Substrate 1 made of non-magnetic material such as ceramic or glass
Above, MR sensors _{M 1, M 2, M 3} , M 4, magnetic cores _{K 1, K 2, K 3} , K 4, and the exciting coils C _1, C
₂ , ₂ , C ₃ , C _4, etc. are all formed by the thin film forming technique.

Specifically, as shown in FIG. 2 (a cross-sectional view in the vicinity of the MR sensor in a direction substantially orthogonal to the longitudinal direction of the MR sensor), an interlayer insulating layer 2 is formed on the substrate 1, Narrower lower conductor layers 3 are radially formed on the interlayer insulating layer 2 at substantially equal intervals.

An interlayer insulating layer 4 and a flattening layer 5 are sequentially formed on the lower conductor layer 3, and the ferromagnetic cores K ₁ , K ₂ , K ₃ , K ₄ (here) are formed on the flattening layer 5. In, the ferromagnetic cores K ₁ and K ₂ ) are formed.

Then, each ferromagnetic core K ₁ , K ₂ ,
An interlayer insulation / planarization layer 6 is formed from K ₃ , K ₄ to the lower interlayer insulation layer 4, the planarization layer 5, and the lower conductor layer 3 except for both ends of the lower conductor layer 3. A narrow upper conductor layer 7 is formed on the flattening layer 6 so as to be connected to both ends of the lower conductor layer 3.

That is, the upper conductor layer 7 has its ends connected to one front end and the other rear end of the adjacent lower conductor layers 3 respectively, and the lower conductor layers 3 and the upper conductor layers 7 are connected to each other. And are integrated to form exciting coils C ₁ , C ₂ ,
C ₃ and C ₄ are integrally formed. The ends of the exciting coils C ₁ , C ₂ , C ₃ , C ₄ are respectively connected to the terminals 12,
It is connected to 13.

In particular, in the present embodiment, the ferromagnetic core K ₁ facing the gaps G ₁ , G ₂ , G ₃ and G ₄ is
Here, the facing surface a near each end of K ₂ , K ₃ , and K ₄ is formed in a tapered shape so that the film thickness gradually decreases toward the end.

The ferromagnetic cores K ₁ , K ₂ ,
Each MR sensor M ₁ , M ₂ , in each of the gaps G ₁ , G ₂ , G ₃ , G ₄ (here, in the gap G ₂ ) having a predetermined width formed by depositing K ₃ , K ₄ is formed. M ₃ and M ₄ (here, MR sensor M ₂ ) are formed. That is,
The MR sensors M ₁ , M ₂ , M ₃ , and M ₄ are embedded in the interlayer insulating layer 2 to form the geomagnetic direction sensor.

Here, as a comparative example of the present embodiment, as shown in FIG. 3, the facing surfaces b of the ferromagnetic core K are formed so as to be substantially perpendicular to the underlying flattening layer 5. Consider the case where it is done.

In this case, the magnetic flux generated in the gap G from the ferromagnetic core S focusing the geomagnetism is substantially evenly distributed between the opposed surfaces b as shown by the arrows in the figure. Therefore, the magnetic flux entering the MR sensor M becomes only a part of the total magnetic flux generated in the gap G, and there is a problem in application efficiency.

Therefore, in the geomagnetic direction sensor according to this embodiment, the ferromagnetic cores K ₁ , K ₂ , K ₃ , K ₄ forming the gaps G ₁ , G ₂ , G ₃ , G ₄ are opposed to each other. Since the surface a is formed in a taper shape, the gap G is formed from the ferromagnetic cores K ₁ , K ₂ , K ₃ , K ₄ focusing the geomagnetism.
_1, G _2, G _3, among the magnetic fluxes generated in the G _4, the gap G _1, G _2, G _3, MR sensors M arranged on the G _4
The amount of magnetic flux entering ₁ , M ₂ , M ₃ and M ₄ increases and the MR
Focus on the sensors M ₁ , M ₂ , M ₃ , M ₄ . for that reason,
The efficiency of applying the magnetic flux to the MR sensors M ₁ , M ₂ , M ₃ and M ₄ of the ferromagnetic cores K ₁ , K ₂ , K ₃ and K ₄ is greatly improved.

Here, when manufacturing the geomagnetic direction sensor, the MR sensors M ₁ , M ₂ , M ₃ , and M ₄ , the ferromagnetic cores K ₁ , K ₂ , K ₃ , and K ₄ and the exciting coil are used. C
₁ , C ₂ , C ₃ , C ₄ , and each interlayer insulating layer (interlayer insulating layer 4, planarizing layer 5, and interlayer insulating / planarizing layer 6) are all formed into a thin film forming step (vacuum deposition, sputtering, etc.). Lamination is performed by a thin film forming technique including a photo etching process.

That is, first, in a thin film forming step, a thin film is formed using a predetermined material by, for example, a sputtering method.

Then, in the photoetching process,
First, a photoresist is applied on the thin film to form a resist layer, and the resist layer is irradiated with light to be exposed according to a photomask having a desired pattern. Then, the resist layer is developed to form a resist mask having a desired pattern on the thin film.

Then, by etching the thin film, each thin film layer having a shape following the pattern of the resist mask is formed.

Here, each gap G ₁ , G ₂ , G ₃ , G
₄ may be formed so as to be gradually narrowed from the inner peripheral edge portion to the outer peripheral edge portion of each of the ferromagnetic cores K ₁ , K ₂ , K ₃ , K ₄ . Thus, the gaps G ₁ , G ₂ , G ₃ , G ₄
By forming the, the magnetic field distributions in the gaps are canceled and the magnetic field becomes uniform regardless of the position in the gap.

The MR sensors M ₁ , M ₂ , M ₃ , M
₄ is, for example, two MR sensors M ₁ for detecting the X-axis direction,
It is classified into M ₃ and two MR sensors M ₂ and M ₄ for detecting the Y-axis direction orthogonal to M ₃ .

An equivalent circuit of the geomagnetic direction sensor having the above structure is as shown in FIG. That is, the signals from the two MR sensors M ₁ and M ₃ for X-axis direction detection are output as X outputs from the differential amplifier A ₁ , and similarly, the two MR sensors M ₂ and M for Y-axis direction detection. The signal from ₄ is output as Y output from the differential amplifier A ₂ .

MR sensors M ₁ , M ₂ , M for geomagnetic detection
_In M ₃ and M ₄ , the constant-potential power supply V _CC is set to the constant-potential power supply, and the sense current is supplied through the terminal 11.

Further, bias magnetic fields (H _B and −H _B ) having different 180 ° azimuths are applied to the MR sensor M ₁ and the MR sensor M ₃ for detecting the X-axis direction, and similarly, for detecting the Y-axis direction. Bias magnetic fields (H _B and −H _B ) having different 180 ° azimuths are also applied to the MR sensor M ₂ and the MR sensor M ₄ .

In the geomagnetic direction sensor having the above structure, M
The R sensors M ₁ , M ₂ , M ₃ and M ₄ have the following features.

(1) The resistance value changes depending on the strength of the magnetic field (magnetoresistance effect). (2) It has an excellent ability to detect a weak magnetic field. (3) The change in resistance value can be taken out as an electric signal.

The geomagnetic direction sensor of the present invention utilizes this feature to convert a magnetic signal due to geomagnetism into an electric signal.

FIG. 5 shows a characteristic curve of the MR sensor. In FIG. 5, the horizontal axis represents the strength of the magnetic field applied vertically to the MR sensor, and the vertical axis represents the change in the resistance value of the MR sensor.
Alternatively, it is an output voltage change (when a direct current is passed through the MR sensor).

The resistance value of the MR sensor becomes maximum when the magnetic field is zero, and is about 3% when a large magnetic field (about 100 to 200 Gauss, depending on the pattern shape of the MR sensor) is applied.
Become smaller.

MR sensor output S / N (output voltage amplitude)
In order to improve the distortion factor, a bias magnetic field H _B is required as shown in FIG. As described above, this bias magnetic field H _B is applied to the second ferromagnetic cores K ₁ , K ₂ ,
Excitation coils C ₁ , C ₂ , C ₃ , and C ₄ are wound around K ₃ and K ₄ , and a bias current I _B is applied to the coils.

At this time, the MR sensor M for detecting the X-axis direction
The direction of the bias magnetic field applied to ₁ and the direction of the bias magnetic field applied to the MR sensor M ₃ are reversed by 180 °. Similarly, the direction of the bias magnetic field applied to the MR sensor M ₂ for detecting the Y-axis direction and the direction of the bias magnetic field applied to the MR sensor M ₄ are also inverted by 180 °.

Here, when the geomagnetic signal H _E comes in,
For example, the strength of the magnetic field applied to the MR sensors M ₁ and M ₃ for detecting the X-axis direction is as follows.

[0058] MR sensors _{M 1: H B + H E} MR sensor M _3: When -H _B + H _E applying an alternating bias magnetic field, the magnetic field applied to the MR sensor M ₁ is changed as shown in FIG. 5 midline A Then, this change in the magnetic field is output as a voltage change as indicated by the line B in FIG. On the other hand, the magnetic field applied to the MR sensor M ₃ is as shown in FIG.
The change occurs as indicated by the middle line C, and this change in the magnetic field is output as a voltage change as indicated by the middle line D in FIG.

An output difference L between the output from the MR sensor M ₁ (line B) and the output from the MR sensor M ₃ (line D) is taken out as a differential signal (X output). The same applies to the MR sensors M ₂ and M ₄ for detecting the Y-axis direction, and the differential signal (Y output) is taken out.

These differential signals change depending on the direction of the geomagnetism H _E and are proportional to H _E sin θ and H _E cos θ, respectively. Therefore, when the output potential is plotted by taking the azimuth θ on the horizontal axis, the X output and the Y output are as shown in FIG.

Therefore, the azimuth θ with respect to the geomagnetism can be calculated from these X output and Y output.

That is, the ratio X / Y of the X output and the Y output is
Since these output is proportional H _E sin [theta, the H _E cos [theta], can be expressed by sin [theta / cos [theta].

X / Y = sin θ / cos θ = tan θ Therefore, θ = tan ⁻¹ (X / Y) (where 0 ≧ θ ≦ 180 °, X ≧ 0, 180 ° <
When θ <360 °, X <0. ) From the above, the direction θ of the geomagnetism H _E can be known.
Next, the principle of geomagnetic focusing by the ferromagnetic cores K ₁ , K ₂ , K ₃ and K ₄ will be described.

First, FIG. 7 schematically shows how the ferromagnetic core K made of ferrite, permalloy or the like affects the earth's magnetism.

Since the ferromagnetic material has a smaller magnetic resistance than that in the air, it is bent so as to attract the earth's magnetism, and passes through the ferromagnetic material core K to come out again.

Therefore, the ferromagnetic core K focuses the earth magnetism and converts it into a large magnetic flux density. (Actually, the earth magnetism magnetizes the ferromagnetic core K and generates a large magnetic field in the gap.) FIG. 8 shows how the earth magnetism is generated when the circular magnet core K is used for each MR sensor M ₁ ,. It shows whether or not it is transmitted to M ₂ , M ₃ , and M ₄ , and each MR sensor M ₁ , M ₂ ,
The total amount of the geomagnetism applied as a magnetic signal to M _3, M ₄ is drawn perpendicular to the geomagnetic line H _EO passing through the center of the magnetic cores K from the MR sensors _{M 1, M 2, M 3} , M 4 Corresponds to the length of the line.

Total amount of geomagnetism applied to X-axis direction detecting MR sensors M ₁ and M ₃ : rsinθ Total amount of geomagnetism applied to Y-axis direction detecting MR sensors M ₂ and M ₄ : rcos θ Therefore, From the geomagnetic orientation sensor output (X output, Y output) output based on the total amount, the azimuth θ of the geomagnetism H _E is calculated according to the above calculation formula.

The same applies to the case where the ferromagnetic core K has a square shape as shown in FIG. 9, and if the shape is symmetrical when the ferromagnetic core K is rotated 90 ° about the center point of the ferromagnetic core K, Similar outputs can be obtained in either case.

As described above, the exciting coils C ₁ , C ₂ ,
Ferromagnetic cores K ₁ and K functioning as C ₃ and C ₄ cores
_{When 2} , K ₃ and K ₄ are made of soft magnetic material and used as a geomagnetic focusing horn, the output is increased and sensitivity is improved compared to when an air-core coil or magnet is used.

Further, in the geomagnetic direction sensor, the ferromagnetic cores K ₁ , K ₂ , K ₃ , K ₄ and the MR sensors M ₁ , M ₂ , M ₃ , M ₄ and the exciting coils C ₁ , C _{2 are used.} ，
C ₃ and C ₄ are integrally formed on the substrate by a thin film forming technique. In this case, for example, as compared with an MR sensor formed on a substrate, a geomagnetic direction sensor manufactured by combining a bulk portion in which a ferromagnetic core is wound and an exciting coil is wound, There are few adjustment points, and the product operating characteristics are extremely stable.

Therefore, the geomagnetism is efficiently supplied to each MR sensor M ₁ , M ₂ , M ₃ , M ₄ as a magnetic signal,
High azimuth accuracy can be obtained, and high precision and a desired small size can be manufactured.

Here, some modified examples of the geomagnetic direction sensor according to the present embodiment will be described. here,
Members and the like corresponding to the geomagnetic direction sensor are denoted by the same reference numerals and the description thereof will be omitted.

[0073] geomagnetic direction sensor of the first modification the first modification has substantially the same configuration as that in the present embodiment, magnetic cores K
_The difference is that the shapes of the facing surfaces of ₁ , K ₂ , K ₃ , and K ₄ are slightly different.

That is, in this geomagnetic direction sensor, as shown in FIG. 10, ferromagnetic cores K ₁ , K ₂ and K are used.
Each of ₃ and K ₄ has a two-layer structure in which a first core 21 and a second core 22 are laminated and formed, and each facing surface c has a stepped shape having a step.

Also in this case, as in the above-mentioned embodiment, the terrestrial magnetism is generated in the gaps G ₁ , G ₂ , G ₃ , G ₄ from the ferromagnetic cores K ₁ , K ₂ , K ₃ , K _4. Of the generated magnetic flux, the amount of magnetic flux entering the MR sensors M ₁ , M ₂ , M ₃ , M ₄ arranged in the gaps G ₁ , G ₂ , G ₃ , G ₄ increases, and the MR sensors M ₁ , M Focus on ₂ , M ₃ , and M ₄ . Therefore, the efficiency of applying the magnetic flux to the MR sensors M ₁ , M ₂ , M ₃ , and M ₄ of the ferromagnetic cores K ₁ , K ₂ , K ₃ , and K ₄ is significantly improved.

Therefore, the geomagnetism is efficiently supplied to each MR sensor M ₁ , M ₂ , M ₃ , M ₄ as a magnetic signal,
High azimuth accuracy can be obtained, and high precision and a desired small size can be manufactured.

[0077] geomagnetic direction sensor of the second modification The second modification, as in the case of the first modification has substantially the same configuration as that in the present embodiment, magnetic cores K _1, K _2, The difference is that the taper shapes of the facing surfaces of K ₃ and K ₄ are slightly different.

That is, in this geomagnetic direction sensor, as shown in FIG. 11, the gaps G ₁ , G ₂ , G ₃ ,
The facing surfaces d of the ferromagnetic cores K ₁ , K ₂ , K ₃ and K ₄ forming G ₄ are substantially arcuate.

Also in this case, as in the above-described embodiment, the magnetic fields are generated in the gaps G ₁ , G ₂ , G ₃ , G ₄ from the ferromagnetic cores K ₁ , K ₂ , K ₃ , K ₄ focusing the geomagnetism. Of the generated magnetic flux, the amount of magnetic flux entering the MR sensors M ₁ , M ₂ , M ₃ , M ₄ arranged in the gaps G ₁ , G ₂ , G ₃ , G ₄ increases, and the MR sensors M ₁ , M Focus on ₂ , M ₃ , and M ₄ . Therefore, the efficiency of applying the magnetic flux to the MR sensors M ₁ , M ₂ , M ₃ , and M ₄ of the ferromagnetic cores K ₁ , K ₂ , K ₃ , and K ₄ is significantly improved.

Therefore, the geomagnetism is efficiently supplied to each MR sensor M ₁ , M ₂ , M ₃ , M ₄ as a magnetic signal,
High azimuth accuracy can be obtained, and high precision and a desired small size can be manufactured.

Although the embodiment to which the present invention is applied has been described above, the present invention is not limited to this embodiment, and the shape, the material, the dimension, etc. are within a range not departing from the gist of the present invention. It can be changed arbitrarily.

[0082]

The geomagnetic direction sensor according to the present invention has practical sensitivity and high azimuth accuracy, and can be miniaturized and finer.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a main part of a geomagnetic direction sensor according to the present embodiment.

FIG. 2 is a transverse cross-sectional view in the direction orthogonal to the longitudinal direction of the MR sensor in the vicinity of the MR sensor of the geomagnetic direction sensor.

FIG. 3 is a cross-sectional view schematically showing a state where each facing surface of the ferromagnetic core is formed so as to be substantially perpendicular to the underlying flattening layer.

4 is an equivalent circuit diagram of the geomagnetic direction sensor shown in FIG.

FIG. 5 is a characteristic diagram showing a characteristic curve of the MR sensor.

FIG. 6 is a characteristic diagram showing a relationship between output voltage and direction.

FIG. 7 is a schematic diagram showing a focused state of geomagnetism by a ferromagnetic core.

FIG. 8 is a schematic diagram showing the total amount of geomagnetism applied to each MR sensor when a circular core is used.

FIG. 9 is a schematic diagram showing the total amount of geomagnetism applied to each MR sensor when a square core is used.

FIG. 10 is an MR of the geomagnetic direction sensor in Modification 1.
It is a cross-sectional view in the direction orthogonal to the longitudinal direction of the MR sensor in the vicinity of the sensor.

FIG. 11 is an MR of the geomagnetic direction sensor in Modification 2;
It is a cross-sectional view in the direction orthogonal to the longitudinal direction of the MR sensor in the vicinity of the sensor.

FIG. 12 is a schematic plan view schematically showing an example of a conventional fluxgate type geomagnetic direction sensor.

FIG. 13 is a schematic plan view schematically showing an example of a conventional MR type geomagnetic direction sensor.

FIG. 14 is an equivalent circuit diagram of the geomagnetic direction sensor shown in FIG.

[Explanation of symbols]

1 Substrate 2,4 Interlayer Insulation Layer 3 Lower Conductor Layer 5 Flattening Layer 6 Interlayer Insulation / Planarization Layer 7 Upper Conductor Layer M ₁ , M ₂ , M ₃ , M ₄ MR Sensor K ₁ , K ₂ , K ₃ , K ₄ Ferromagnetic core G ₁ , G ₂ , G ₃ , G ₄ Gap C ₁ , C ₂ , C ₃ , C ₄ Excitation coil

Claims (3)

[Claims] 1. A plurality of ferromagnetic cores arranged in the circumferential direction with a predetermined gap for concentrating geomagnetism, and a magnet arranged in the gap so as to be substantially orthogonal to the magnetic field direction in the gap. A resistance effect element, and an exciting coil that is wound around the ferromagnetic core via an interlayer insulating layer and applies a bias magnetic field to the magnetoresistive effect element by supplying a current. The magnetoresistive effect element, the exciting coil, and the interlayer insulating layer are formed on the substrate by a thin film forming technique, and the film thickness gradually increases in the vicinity of the end of each ferromagnetic core facing the gap toward the end. The geomagnetic direction sensor is characterized in that it is formed so as to decrease. 2. The geomagnetic direction sensor according to claim 1, wherein the facing surfaces of the ferromagnetic cores forming the gap are formed in a step shape or an arc shape having a step. 3. The geomagnetic direction sensor according to claim 1, comprising at least a pair of magnetoresistive effect elements that are substantially orthogonal to each other.