JPH0727565A - Geomagnetic direction sensor - Google Patents

Abstract

PURPOSE:To improve the precision for determining a direction by directly determining the direction, and numerically reading it. CONSTITUTION:A bottomed cylindrical container 1 made of a nonmagnetic material is prepared, a spindle 2 is planted from the center of the bottom section of the container 1 toward the upper end opening, and a magnetic needle 3 is rotatably fitted at the tip of the spindle 2. Many MR elements 4 made of a ferromagnetic material, e.g. Ni-Fe(83%), are arranged at a uniform pitch so that theiraxes are easily aligned along the axial direction of the container 1, and ferromagnetic materials 5a, 5b are provided on both tip sections of the magnetic needle 3 to constitute a geomagnetic direction sensor. A strong magnet having the magnetic field strength determining the operating point on the R(rho)-H characteristic for the MR elements 4, e.g. Co-Sm, is used for the ferromagnetic materials 5a, 5b provided at both tip sections of the magnetic needle 3.

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 made of a ferromagnetic material or a magnetoelectric semiconductor material.

[0002]

2. Description of the Related Art As a conventional geomagnetic direction sensor, a magnet type geomagnetic direction sensor as shown in FIG. 10 is known.

The geomagnetic direction sensor shown in FIG. 10 has a structure in which a magnetic needle 102 for indicating a direction is rotatably supported at the upper end at the center of a direction board 101. Around the azimuth plate 101, symbols representing north, east, south and west are clockwise N, E,
It is printed in English letters S and W.

[0004]

However, the above-mentioned conventional magnet type geomagnetic direction sensor has a problem that it takes time to determine the direction because the acceleration of rotation, vibration, etc. affects the magnetic needle due to the moment of inertia. Further, there is a problem that the azimuth angle cannot be read numerically and the azimuth determination accuracy is insufficient.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a geomagnetic direction sensor capable of direct direction determination and numerical reading, and improving the accuracy of direction determination. To provide.

[0006]

In the geomagnetic direction sensor according to the present invention, a plurality of magnetoresistive effect elements 4 (or 11) are arranged on the inner circumference of a cylindrical container 1 along the circumference thereof, A magnetic needle 3 that is rotatable in the axial direction is arranged in the container 1, and ferromagnetic materials 5a and 5b are provided at the tip of the magnetic needle 3.

In this case, the plurality of magnetoresistive effect elements 4 are
(Or 11) can be formed in a strip shape, and each long axis can be arranged on the inner circumference of the container 1 along the axial direction of the container 1. Further, as the ferromagnetic material 5 a and 5 b provided at the tip of the magnetic needle 3, the magnetoresistive effect element 4 is used.
For (or 11), it is preferable to use one that generates a magnetic field that determines the operating point on the resistance-magnetic field characteristics.

The plurality of magnetoresistive effect elements 4 (or 11) may be made of a ferromagnetic material or a magnetoelectric semiconductor material.

[0009]

In the geomagnetic direction sensor according to the present invention,
First, the magnetic needle 3 rotatably arranged in the container 1 rotationally moves in the axial direction of the container 1 in the direction in which the external magnetic field, that is, the geomagnetism H _E acts, and each tip portion follows the direction of the geomagnetism H _E. It becomes a form. At this time, among the many magnetoresistive effect elements 4 (or 11) arranged on the inner peripheral surface of the container 1, the geomagnetism H
Magnetoresistive element 4a (or 11a) arranged closest to the tip of the magnetic needle 3 rotated by _E
And 4b (or 11b), a magnetic field is applied by the ferromagnetic material 5a and 5b provided at the tip of the magnetic needle 3, and the magnetoresistive effect elements 4a (or 11a) and 4b.
(Or 11b) changes its resistance to the operating point A on the resistance-magnetic field characteristics of the magnetoresistive effect elements 4a (or 11a) and 4b (or 11b) by applying the magnetic field. Resistance effect element 4a (or 11
Since acting geomagnetic H _E in a) and 4b (or 11b), from the operating point A, which is determined by the ferromagnetic material 5a and 5b, depending on the magnetic field intensity of the geomagnetism H _E that the working It will change as much as the resistance.

At this time, a plurality of magnetoresistive effect elements 4 other than the magnetoresistive effect elements 4a (or 11a) and 4b (or 11b) whose resistances have been changed to the above operating point are used.
(Or 11) is hardly affected by the magnetic field by the ferromagnetic materials 5a and 5b, and therefore only a slight resistance change due to the geomagnetism H _E occurs. From the viewpoint of resistance-magnetic field characteristics, this change is almost a change in the dead zone level, and it can be considered that there is almost no equivalent change in resistance.

From the above, regarding the plurality of magnetoresistive effect elements 4 (or 11) arranged on the inner peripheral surface of the container 1,
The direction of the geomagnetism H _E can be known by detecting the change in each resistance. Moreover, the azimuth of the geomagnetism H _E can be detected numerically, and the accuracy in determining the geomagnetic azimuth can be improved.

[0012]

EXAMPLE An example of a geomagnetic direction sensor according to the present invention (hereinafter, simply referred to as an example sensor) is shown in FIG.
-It demonstrates, referring FIG.

As shown in FIG. 1, the sensor according to this embodiment is made of, for example, a non-magnetic material and has a height of about 3 to 3.
It has a bottomed cylindrical container 1 of 4 mm, and a support shaft 2 is planted from the center of the bottom of the container 1 toward the upper end opening,
A magnetic needle 3 is rotatably attached to the tip of the support shaft 2. The magnetic needle 3 is a needle-shaped strong magnet such as an aluminum magnet (Al-Fe). Further, in FIG. 1, N and S displayed on the magnetic needle 3 indicate the magnetization direction of the magnetic needle.

Further, in this sensor, a large number of magnetoresistive effect elements (hereinafter simply referred to as MR elements) 4 made of a ferromagnetic material such as Ni-Fe (83%) are provided on the inner peripheral surface of the container 1. The easy axes are arranged at equal pitches along the axial direction of the container 1, and the magnetic needles 3 are provided with ferromagnetic materials 5a and 5b at both ends thereof.

As shown in FIG. 2, the single MR element 4 is formed by forming a FeNi-based ferromagnetic film (resistance change rate of 3%) on a base glass (not shown) by a vapor deposition method or the like. After doing
Patterning is performed by a dry process such as photolithography to form the strip-shaped MR element 4. This M
Electrode conductors 6a and 6b made of Cu are formed on both ends of the R element 4. In this embodiment, the length n of the sensing portion of the MR element 4 is 3 mm, the width w is 20 μm, and the thickness is about 50 nm.

Each of the MR elements 4 has one of the side surfaces (of which the area along the easy axis has a smaller area) is attached to the inner peripheral surface of the container 1 by, for example, an adhesive. Each hard shaft is positioned in the direction toward the support shaft 2.

Here, as the ferromagnetic materials 5a and 5b provided on both ends of the magnetic needle 3, the magnetic field strength that determines the operating point on the R (ρ) -H characteristic of the MR element 4 is set. Use what you have. That is, when the saturation magnetic field strength Hs of the MR element 4 is 200 [Oe], for example, a ferromagnetic material having a magnetic field strength H _MS of 50 to 150 [Oe] is used. Examples of the materials 5a and 5b include Co-Sm.
A strong magnet such as is suitable.

In the actual measurement of the resistance value of each MR element 4, as shown in FIG. 1, a lead wire (not shown) is connected to an electrode (for example, the electrode 6b shown in FIG. 2) on the bottom side of the container 1 in each MR element 4. ) To electrically form a common terminal φc, and the other electrode (for example, the electrode 6a shown in FIG. 2) is connected to a large number of input terminals derived from the scanner device 7. The common terminal φc is connected to one input terminal of the tester 8 connected to the latter stage of the scanner device 7.

The basic structure of the scanner device 7 is equivalent to a structure in which a switch having a large number of input terminals as fixed contacts and a common output terminal as a movable contact is incorporated. It switches based on the input of the control signal (for example, clock pulse) Sc of.
The output terminal of the scanner device 7 is connected to the other input terminal of the tester 8.

Then, the resistance value of each MR element 4 is measured by the tester 8 by sequentially switching the switches in the scanner device 7 based on the input of the control signal Sc from the tester 8.

The change in the resistance value of the MR element 4 due to the external magnetic field will be described below with reference to FIGS. 3 and 4.
As shown in FIG. 3, when the external magnetic field Hex is applied to the MR element 4, the resistance value R at both ends of the MR element 4 is expressed by the following equation (1).

[0022]

[Equation 1]

From the above equation (1), the relationship of the change of the resistance value R of the MR element 4 with respect to the change of the external magnetic field Hex (or θ), that is, the RH (ρ-H) characteristic is shown in the characteristic diagram of FIG. Can be shown.

Next, the principle of detecting the geomagnetic azimuth angle by the sensor according to the above embodiment will be described.

First, the magnetic needle 3, which is rotatably attached to the support shaft 2 in the container 1, rotationally moves in the direction in which the geomagnetism H _E acts, and both tip portions are in a shape along the direction of the geomagnetism H _E. At this time, of the large number of MR elements 4 arranged on the inner peripheral surface of the container 1, a pair of MR elements 4a and a pair of MR elements 4a arranged closest to each tip of the magnetic needle 3 rotated by the geomagnetism H _E. A magnetic field is applied to 4b by the ferromagnetic material 5a and 5b provided at both ends of the magnetic needle 3.

[0026] Here, MR elements 4a that faces the N pole of the compass needle 3, a ferromagnetic material 5a provided at the distal end of the N pole of the magnetic needle 3 (+) to the direction of the magnetic field H _MS is applied Thus, the MR element 4b facing the south pole of the magnetic needle 3 is applied with the magnetic field H _{MS in the} (−) direction by the ferromagnetic material 5b provided at the tip of the south pole of the magnetic needle 3.

Therefore, the pair of MR elements 4a and 4b
When the magnetic fields are applied from the corresponding ferromagnetic materials 5a and 5b, the respective resistance values are up to the operating point A on the R (ρ) -H characteristic, as shown in FIGS. 5 (a) and 5 (b). It will change. In this case, the pair of MR elements 4
changes from the terrestrial magnetism H _E is acting in a and 4b, from the operating point A, which is determined by the ferromagnetic material 5a and 5b, as the resistance component in accordance with the magnetic field intensity of the geomagnetism H _E that the working To do. That is, the respective resistance values of the pair of MR elements 4a and 4b are equal to the geomagnetism H _E from the operating point A by the magnetic field application from the ferromagnetic materials 5a and 5b, respectively.
The values correspond to the points A1 and A2 shifted to the side.

At this time, among the plurality of MR elements 4,
The MR elements 4 other than the pair of MR elements 4a and 4b are
As shown in FIG. 5C, since the ferromagnetic materials 5a and 5b are hardly affected by the magnetic field, only a slight resistance change due to the geomagnetism H _E occurs. That is, the magnetic field strength of the geomagnetism H _E is much smaller than the magnetic field strengths of the ferromagnetic materials 5a and 5b provided at both ends of the magnetic needle 3, and its absolute value is 0.4 [Oe] or less. is there. Accordingly, the resistance change of the MR element 4 only by terrestrial magnetism H _E is, R (ρ) -H
In terms of characteristics, it can be considered that the dead zone level is almost the same, and equivalently the resistance value hardly changes.

From this fact, of the many MR elements 4 mounted on the inner peripheral surface of the container 1, M having the lowest resistance value is used.
R element (in this case, MR elements 4a) by detecting, so that the orientation of the geomagnetism H _E is determined.

Specifically, the scanner device 7 shown in FIG.
The switches inside are sequentially switched based on the input of the control signal Sc from the tester 8, the resistance value of each MR element 4 is measured by the tester 8, and the arrangement direction of the MR element having the lowest resistance value is the geomagnetic direction. .

In order to recognize the direction of the geomagnetism as, for example, numerical data, the following structure can be adopted, for example.

That is, in the measurement of the geomagnetic direction, a reference MR element (for example, shown as the MR element 4c in FIG. 1) is previously determined, and the array angle of each MR element 4 with respect to the reference MR element 4c is determined. , And the array numbers of the respective MR elements 4 are stored in a predetermined array variable area of the memory incorporated in the tester 8.

The MR device (array number) having the lowest resistance value is searched by the switching by the scanner device 7 and the resistance value of each MR device 4 detected by the tester 8, and the array element number of the searched MR device is searched. Based on the above, the array angle corresponding to the array number stored in the memory is read out, and the read array angle is displayed as a azimuth angle of the geomagnetism H _{E on} the liquid crystal display, for example, on the operation panel of the tester 8. To

In this way, the azimuth of the geomagnetism H _E can be recognized as objective numerical data, and the accuracy of the sensor for detecting the azimuth is significantly improved.

Next, a modification of the sensor according to the above embodiment will be described with reference to FIG. The same reference numerals are given to those corresponding to FIG.

As shown in FIG. 6, the sensor according to this modification has substantially the same structure as the sensor according to the above-mentioned embodiment, but InSb, InAs, In is used as the MR element 4.
Magnetoelectric semiconductor element 11 such as AsP, GaAs, Si, Ge
The difference is that you used.

In this case, as shown in FIG. 7, for example, the length n of the sensing portion is 3 mm, the width w is 20 μm, and the thickness t is 50 n.
An MR element is formed by forming electrodes 12a and 12b made of Au on both ends of a strip-shaped magnetoelectric semiconductor element 11 of m. The application direction of the external magnetic field component H _S that contributes to the resistance change is a direction that penetrates the plate surface of the magnetoelectric semiconductor element 11 in the vertical direction. Further, the R (ρ) -H characteristic of the electromagnetic semiconductor element 11 has a characteristic that the resistance value thereof increases exponentially as the absolute value of the applied magnetic field increases, as shown in FIG. The characteristics are opposite to those of the MR element 4 made of the ferromagnetic material used in the above embodiment.

Therefore, in this modified example, as shown in FIG. 6, when a large number of magnetoelectric semiconductor elements 11 are attached to the inner peripheral surface of the container 1, the main surface of the electromagnetic semiconductor element 11 (the surface along the major axis). Among them, one of the main surfaces (having a large area) is attached to the inner peripheral surface of the container 1 by, for example, an adhesive or the like.

Next, the principle of detecting the azimuth angle of the geomagnetism H _E by the sensor according to the above modification will be described.

First, the magnetic needle 3 rotatably attached to the support shaft 2 in the container 1 rotationally moves in the direction in which the geomagnetism H _E acts, so that both tips are in the shape of the geomagnetism. At this time, among a number disposed on the inner peripheral surface of the container 1 pieces of magnetoelectric semiconductor element 11, a pair being arranged at closest to the both ends of the magnetic needle 3 that rotationally moved by the terrestrial magnetism H _E magnetoelectric semiconductor element Magnetic fields (H _MS ) and (−H _MS ) generated by the ferromagnetic materials 5a and 5b provided at both ends of the magnetic needle 3 are applied to 11a and 11b, and the pair of magnetoelectric semiconductor elements 11a and 11b are 9 (a) and 9 (b) by applying a magnetic field from the ferromagnetic materials 5a and 5b.
As shown in, each resistance value changes up to the operating point A on the R (ρ) -H characteristic. In this case, since the acting geomagnetic H _E in the pair of magneto-electric semiconductor elements 11a and 11b, the operating point A, which is determined by the ferromagnetic material 5a and 5b, a geomagnetic H _E that the working
The resistance changes according to the strength of the magnetic field.

At this time, among the plurality of magnetoelectric semiconductor elements 11, the magnetoelectric semiconductor elements 11 other than the pair of magnetoelectric semiconductor elements 11a and 11b are as shown in FIG. 9 (c).
Since not subjected almost the action of the magnetic field by ferromagnetic materials 5a and 5b, the only slight resistance change due to terrestrial magnetism H _E. Therefore, the magnetoelectric semiconductor element 1 based only on the geomagnetism H _E
The resistance change of No. 1 is almost a change in the dead zone level on the R (ρ) -H characteristic, and it can be considered that there is almost no change in resistance equivalently.

From the above, it is possible to know the direction of the geomagnetism H _E by detecting the change in each resistance value of the plurality of magnetoelectric semiconductor elements 11 arranged on the inner peripheral surface of the container 1. Specifically, the switches in the scanner device 7 shown in FIG. 6 are sequentially switched based on the input of the control signal Sc from the tester 8, and the resistance value of each electromagnetic semiconductor element 11 is measured by the tester 8 to obtain the highest resistance value. The direction of arrangement of the electromagnetic semiconductor element 11 having a high magnetic field is the direction of geomagnetism.

Also in this modified example, as in the above-described embodiment, a structure capable of recognizing the geomagnetic direction as numerical data can be adopted. That is, in the measurement of the geomagnetic direction, a reference magnetoelectric semiconductor element (for example, FIG.
In the electromagnetic semiconductor element 11c) is determined in advance, and the arrangement angle of each magnetoelectric semiconductor element 11 with respect to this reference magnetoelectric semiconductor element 11c is determined by the magnetoelectric semiconductor element 1c.
It is stored together with the array element number of 1 in a predetermined array variable area of the memory incorporated in the tester 8.

Then, by the switching by the scanner device 7 and the detection of the resistance value of each magnetoelectric semiconductor element 11 by the tester 8, the magnetoelectric semiconductor element 1 having the highest resistance value is obtained.
1 searching (SEQ ID NO:), based on the sequence number of the magneto-electric semiconductor element 11 and the search reads the arrangement angle corresponding to SEQ number stored in the memory, the arrangement angle of the readout of the geomagnetism H _E As an azimuth angle, a character is displayed on, for example, a liquid crystal display on the operation panel of the tester 8.

In this way, the azimuth of the geomagnetism H _E can be recognized as objective numerical data, and the accuracy in detecting the azimuth of the sensor is greatly improved.

[0046]

As described above, according to the geomagnetic direction sensor of the present invention, a plurality of magnetoresistive effect elements are arranged on the inner circumference of a cylindrical container along the circumference thereof, and the magnetoresistive effect element is arranged in the container. Since a magnetic needle that is rotatable in the axial direction is provided and a ferromagnetic material is provided at the tip of the magnetic needle, direct azimuth determination and numerical reading are possible, and the accuracy of azimuth determination is improved. You can

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a geomagnetic direction sensor according to the present invention.

FIG. 2 is a plan view showing an MR element made of a ferromagnetic material used in the geomagnetic direction sensor according to the example.

FIG. 3 is an explanatory diagram showing vector analysis of resistance change when an external magnetic field is applied to the MR element.

FIG. 4 is a characteristic diagram showing a change in resistance value (R (ρ) -H characteristic) of the MR element with respect to a change in an external magnetic field (or θ).

FIG. 5 is an explanatory diagram showing the principle of detecting the azimuth angle of the geomagnetism by the geomagnetic azimuth sensor according to the present embodiment based on the R (ρ) -H characteristic of the MR element, and FIG. 5 (a) is the N pole of the magnetic needle. Shows the R (ρ) -H characteristic of the MR element facing to, and the figure (b) shows the R (ρ) -H of the MR element facing to the S pole of the magnetic needle.
The characteristics of the MR element are shown in FIG.
(Ρ) -H characteristics are shown.

FIG. 6 is a configuration diagram showing a modification of the geomagnetic direction sensor according to the present embodiment.

FIG. 7 is a perspective view showing a magnetoelectric semiconductor element used in a geomagnetic direction sensor according to a modification.

FIG. 8 is a characteristic diagram showing a change in resistance value (R (ρ) -H characteristic) of the magnetoelectric semiconductor element with respect to a change in the external magnetic field H.

FIG. 9 shows the principle of detection of the azimuth angle of the geomagnetism by the geomagnetic azimuth sensor according to the modification as R (ρ) -H of the magnetoelectric semiconductor element.
It is explanatory drawing shown based on a characteristic, the figure (a) shows the R ((rho))-H characteristic of the magnetoelectric semiconductor element which opposes the N pole of a magnetic needle, and the same figure (b) opposes the S pole of a magnetic needle. The R (ρ) -H characteristic of the magnetoelectric semiconductor element is shown, and the figure (c) shows the R (ρ) -H characteristic of the other magnetoelectric semiconductor elements.

FIG. 10 is a plan view showing a magnet type geomagnetic direction sensor according to a conventional example.

[Explanation of symbols]

 1 container 2 spindle 3 magnetic needle 4 MR element (ferromagnetic material) 5a and 5b ferromagnetic material 6a and 6b electrode 7 scanner device 8 tester 11 magnetoelectric semiconductor element

Claims (5)

[Claims] 1. A cylindrical container is provided with a plurality of magnetoresistive effect elements along the circumference of the inner periphery thereof, and a magnetic needle rotatable in the axial direction is arranged in the container. A geomagnetic direction sensor having a ferromagnetic material at its tip. 2. The magnetoresistive effect element is formed in a strip shape, and a long axis of each is arranged on an inner circumference of the container along an axial direction of the container. 1. Geomagnetic direction sensor according to 1. 3. The geomagnetism according to claim 1, wherein the ferromagnetic material generates a magnetic field that determines an operating point on the resistance-magnetic field characteristic of the magnetoresistive effect element. Direction sensor. 4. The magnetoresistive effect element is formed of a ferromagnetic material.
The geomagnetic direction sensor according to 2 or 3. 5. The geomagnetic direction sensor according to claim 1, wherein the plurality of magnetoresistive effect elements are formed of a magnetoelectric semiconductor material.