JPH06288770A - Earth magnetism azimuth sensor - Google Patents

Abstract

PURPOSE:To determine the direct azimuth, improve the accuracy of the azimuth, and provide a preferable manufacturing method. CONSTITUTION:Sixteen strip-shaped MR elements 1 are prepared, and these MR elements 1 are arranged at the position of each angle theta which is uniformly divided in the 360 deg. plane of the circumference of a glass plate (not shown in the figure) in the axial direction along the radial direction to constitute a sensor body 2. In addition, a solenoid coil 3 whose center in the winding direction is along the circumference is coiled around this sensor body 2. The divided angle theta is defined by the formula theta=360 deg./n, and in this example, the divided angle is 360 deg./16=22.5 deg. because sixteen MR elements are used. The uniform bias magnetic field HB is applied in the arrangement direction of the MR elements 1, i.e., in the circumferential direction of the MR elements 1 as indicated by the arrow by applying the bias current 10 to the solenoid coil 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.

[0002]

2. Description of the Related Art As a conventional geomagnetic direction sensor, a magnet type geomagnetic direction sensor as shown in FIG. 21 is known.

The geomagnetic direction sensor shown in FIG. 21 has a structure in which a magnetic needle (not shown) having a pointer 102 for indicating the direction at the upper end is rotatably supported at the center of the direction board 101. Around the azimuth plate 101, symbols representing north, east, south, and west are printed in clockwise N, E, S, W letters.

The magnet type geomagnetic direction sensor shown in FIG. 21 has a problem that it takes time to determine the direction because acceleration of rotation, vibration, etc. affects the magnetic needle due to the moment of inertia. There was also a problem with durability and vibration resistance. In addition, there is also a problem that the accuracy of azimuth determination is insufficient.

Therefore, conventionally, a geomagnetic direction sensor having two magnetoresistive effect elements (hereinafter, simply referred to as MR elements) arranged orthogonally has been proposed (for example, Japanese Patent Laid-Open No. 6-242242).
No. 1-262613).

In this geomagnetic direction sensor, the magnetic field to be measured is measured by two MR elements arranged orthogonally, and the measured values are vector-synthesized to obtain the geomagnetic direction. According to this geomagnetic direction sensor, since there is no moving part unlike the magnet type geomagnetic direction sensor, there are advantages that it is excellent in durability and vibration resistance, and that the direction can be determined in a short time.

[0007]

However, in the geomagnetic direction sensor using the two MR elements arranged orthogonally, the magnetic field is measured only by the two MR elements, so that the measured value is not accurate and the electric value is not enough. The error becomes large because the process of the dynamic vector composition operation intervenes.

[0008] Here, a trial calculation of the geomagnetic sensing output using a currently used ordinary MR element will be made. First, an MR element composed of a FeNi-based ferromagnetic film (rate of change in resistance Δρ / ρ = 3
%, And the anisotropic magnetic field Hc = 50 [Oe]), the resistance change characteristic (Δρ−H characteristic) with respect to the external magnetic field draws the characteristic curve shown in FIG.

When the DC bias magnetic field H _B is set at the center of the straight line portion of the characteristic curve, the resistance value is effectively 0 with respect to the earth magnetism whose maximum change width is 0.5 [Oe]. Only a change of 0.03% is obtained.

Under such a background, it can be seen that the method of electrically synthesizing vectors to determine the azimuth is not reliable. In addition, since the Δρ-H characteristic of the MR element needs to be linear in setting the bias point, there is a problem that the MR element is technically restricted in the manufacturing method (in particular, heat treatment).

As described above, the conventional geomagnetic azimuth sensor lacks the reliability of azimuth determination, and even if it is put into practical use, it is necessary to take measures to improve the auxiliary circuits related to the sensor (synthetic vector arithmetic circuit etc.). become,
It is expensive overall. In addition, since the sensor body has a so-called bulk structure in which the toroidal core is subjected to the winding process, the number of circuits is large and complicated, which causes increase in power consumption, weight, and size.

The present invention has been made in view of the above problems, and its object is to enable direct azimuth determination, high azimuth accuracy, a small number of circuit points, and a linear Δρ-H characteristic. The purpose of the present invention is to provide a geomagnetic direction sensor that does not require the property and is advantageous in terms of manufacturing.

Another object of the present invention is to provide a geomagnetic direction sensor which can reduce the bias current required for generating a bias magnetic field and can suppress the occurrence of circuit drift.

[0014]

In the geomagnetic direction sensor according to the present invention, a large number of magnetoresistive effect elements 1 are 360 °.
A sensor body 2 arranged along a circumference or an arc having a circumference angle of 180 ° or more, and respective easy axes arranged along the radial direction of the circumference or the arc, and a bias magnetic field in a tangential direction of the circumference or the arc. And a means for applying H _B.

Structurally, the following is desirable. That is, the number of winding grooves 31 formed of a magnetic material having a high magnetic permeability in a plane circumference or an arc shape having a circumference angle of 180 ° or more and corresponding to the number of the magnetoresistive effect elements 1.
A magnetic core 33 provided with a magnetic gap 32 communicating with the winding groove 31 is prepared, the magnetoresistive effect element 1 is formed on each magnetic gap 32 of the magnetic core 33, and the winding groove is formed. A winding 35 for applying a bias magnetic field H _B to each magnetoresistive effect element 1 is wound around 31.

[0016]

In the geomagnetic direction sensor according to the present invention,
Since a large number of magnetoresistive effect elements (hereinafter, simply referred to as MR elements) 1 are arranged, the measurement magnetic field is measured at a large number of points, and the azimuth determination accuracy becomes high.
Moreover, a large number of MR elements 1 have a circumference or a circumference angle of 180
Since the easy axes are arranged along an arc of not less than ° and along the circumference or the radial direction of the arc, the measured values of the MR elements 1 are correlated and the accuracy is high. A high azimuth determination is possible. Moreover, it is not necessary to take special measures against external noise and drift.

When actually determining the direction of the geomagnetism, the resistance value of each MR element 1 changed by the geomagnetism is electrically detected, and the detected value of each MR element 1 and the MR elements 1 adjacent to each other are detected. The azimuth of the geomagnetism is directly determined from the correlation between the resistance values of. In this case, it is possible to determine the azimuth of the geomagnetism from each resistance value of at least three consecutive MR elements 1.

As described above, in the geomagnetic direction sensor according to the present invention, since the geomagnetic direction can be determined directly from the resistance value of the MR element 1, an auxiliary circuit such as a conventional vector combining arithmetic circuit is unnecessary. Therefore, the entire configuration is downsized. Further, basically, the Δρ-H characteristic of the MR element 1 does not require linearity, and therefore, in terms of bias setting and MR.
The technical restrictions on the manufacturing method of the element 1 are released, and the degree of freedom in design can be improved.

The level of the sense current flowing through the MR element 1 is usually 0.1 to 1 mA, but in the case of the present invention,
Since it is sufficient to measure the resistance value of the MR element 1, one MR
The sense current flowing in the element 1 can be set to the order of .mu.A, and low power consumption can be achieved.

In particular, a magnetic material having a high magnetic permeability is formed in a plane circumference or a circular arc shape having a circumference angle of 180 ° or more, and the number of winding grooves 31 corresponding to the number of MR elements 1 and this winding. Line groove 31
Magnetic core 33 provided with a magnetic gap 32 communicating with
When the MR element 1 is formed on each of the magnetic gaps 32 of the magnetic core 33 to form the sensor body, the batch work by the photolithography process can be adopted, and the workability is improved. With
Variations in characteristics among the formed MR elements 1 are reduced.

Moreover, a bias magnetic field H _{B is applied} to each MR element 1.
The level of the bias current I0 for applying the voltage can be significantly reduced, the circuit-like drift occurring in the sensor body can be effectively suppressed, and the power consumption is reduced in combination with the reduction of the sense current level. Is advantageous in reducing

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A geomagnetic direction sensor using a magnetoresistive effect element (hereinafter simply referred to as an MR element) according to the present invention is a system for automatically correcting a mislanding caused by geomagnetism in an ultra high definition cathode ray tube. Used as a sensor for geomagnetic detection.

Normally, in a color cathode ray tube, the orbit of an electron beam emitted from an electron gun is bent by the geomagnetism, and the beam arrival position (landing) on the fluorescent screen changes. Particularly, in a high-definition cathode ray tube, since the landing margin is small, this landing position shift causes a problem such as deterioration of color purity.

In order to correct this, a landing correction coil is attached to the cathode ray tube, and an optimum current necessary for landing correction is automatically supplied to the landing correction coil in accordance with the direction and strength of the earth's magnetism. Is controlled to prevent mislanding.

The geomagnetic direction sensor according to the present invention is used for detecting the geomagnetic direction in such mislanding correction.

Further, it is also used as a portable azimuth meter as a substitute for a magnet type geomagnetic azimuth sensor (magnetic compass) which has been conventionally used.

Some embodiments of the geomagnetic direction sensor according to the present invention will be described below with reference to FIGS.

First, in the geomagnetic direction sensor according to the first embodiment, as shown in FIG. 1, a large number of strip-shaped magnetoresistive effect elements (hereinafter, simply referred to as MR elements) 1 are provided, and in this embodiment, 16 pieces are provided. As shown in the drawing, these MR elements 1 are prepared by, for example, dividing the easy axis direction into circles at positions of respective angles θ equally divided in a 360 ° circumferential plane of a glass plate (not shown). Sensor body 2 arranged along the radial direction
Is configured.

In this case, the division angle θ is θ = 360 ° /
In the example of FIG. 1, since 16 MR elements are used, the division angle is 360 ° / 16 = 22.5 °. Also, of course, the nth and (n + 8) th are
It becomes the relation of 180 ° relative position, and it is n-th and (n + 4)
The second has a relative position relationship of 90 °.

Then, as shown in FIG. 2, the sensor bodies 2 are evenly arranged in a 360 ° circumferential plane.
Solenoid coil 3 whose center in the winding direction is along the circumferential direction
Is wound to form the geomagnetic direction sensor according to the first embodiment. By supplying a bias current (DC or AC) I0 to the solenoid coil 3, a uniform bias magnetic field HB is applied in the arrangement direction of the MR elements 1, that is, in the circumferential direction, as shown by the arrow.

As shown in FIG. 3, a single MR element 1 is formed by forming a FeNi-based ferromagnetic film (resistance change rate 3%) on a base glass (not shown) by vapor deposition or the like. After doing
Patterning is performed by a dry process such as photolithography to form the strip-shaped MR element 1. This M
Electrode conductors 4a and 4b made of Cu are formed on both ends of the R element 1. In this embodiment, the length n of the sensing portion of the MR element 1 is 10 mm, the width w is 10 μm, and the thickness is 50 to 10.
It is 0 nm.

The actual measurement of the resistance value of each MR element 1 is, as shown in FIG. 4, electrically connected to the electrode 4a on the circumferential center side of each MR element 1 by a conductor 5 to form a common terminal, The other electrode 4b is connected to a large number of input terminals derived from the scanner device 6. The common terminal c is connected to one input terminal of the tester 7 connected to the subsequent stage of the scanner device 6.

The basic configuration of the scanner device 6 is constructed by incorporating a switch S having a large number of input terminals as fixed contacts and a common output terminal as a movable contact, and the switch S is manually operated from the outside. It is switched by the switching operation. The output terminal of the scanner device 6 is connected to the other input terminal of the tester 7.

Then, the resistance value of each MR element 1 is measured by the tester 7 by manually switching the switches S in the scanner device 6 sequentially.

Here, the change of the resistance value of the MR element 1 due to the external magnetic field will be described with reference to FIGS. 5 and 6, first,
As shown in FIG. 5, when the external magnetic field Hex is applied to the MR element 1, the resistance value R at both ends of the MR element 1 is expressed by the following equation (1).

[0036]

[Equation 1]

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

Next, the operation when a large number of MR elements 1 are circumferentially arranged in 360 ° will be described with reference to FIGS. 7 to 9.
Here, in order to simplify the description, the RH of the MR element 1 is
The (ρ-H) characteristic is treated as a linear characteristic as shown in FIG. 7. Note that the effectiveness of the present invention is not impaired at all by handling the RH characteristics linearly. This Figure 7
, H _B indicates a bias magnetic field applied to the MR element 1, and R _B indicates M when the bias magnetic field H _B is applied.
The resistance value of the R element 1 is shown.

From this FIG. 7, the following expression (2) is derived: R = −3H + R _B + 3H _B (2)

[0040] Then, an external magnetic field (geomagnetism: H _E) state of each MR element 1 when there is no, only uniform bias magnetic field H _B to the circumference of the tangential (hard axis) in the MR element 1 Since the voltage is applied, each M is determined from the RH characteristics shown in FIG.
The resistance value of the R element 1 is uniquely determined to be R _B.

Next, when there is an external magnetic field (geomagnetism: H _E ), the resistance value of each MR element 1 differs depending on the direction of the external magnetic field H _E.

[0042] As an example, as shown in Figure 8A, if there is an arrow direction of the external magnetic field H _E, the hard axis direction component of the external magnetic field H _E applied to each MR element 1, the bias of each MR element 1 The combined magnetic field of the hard-axis direction component of the magnetic field H _B and the external magnetic field H _E , the resistance value of each MR element 1 and the voltage between both electrodes of each MR element 1 (terminal voltage) are shown in Table 1 below. The operation point (resistance value) on the RH characteristic of each MR element is as shown in FIG. 8B.

[0043]

[Table 1]

Further, as shown in FIG. 9A, when there is an external magnetic field H _{E in the} direction opposite to that of FIG. 8A, the component in the hard axis direction of the external magnetic field H _E applied to each MR element 1 and each MR element 1 The combined magnetic field of the hard magnetic field component of the bias magnetic field H _B and the external magnetic field H _E in No. 1, the resistance value of each MR element 1 and the voltage between both electrodes of each MR element 1 (voltage between terminals) are shown in the table below. 2 and the operating point (resistance value) on the RH characteristic of each MR element 1 is as shown in FIG. 9B.

[0045]

[Table 2]

The orientation of the external magnetic field H _E shown in FIGS. 8A and 9A can be determined by, for example, the following six methods.

That is, in the first method, three consecutive MR elements 1 of the sixth, seventh and eighth are selected by the scanner device 6 shown in FIG. This is a method of detecting the value and determining the azimuth.

First, in the external magnetic field H _E in the direction shown in FIG. 8A, the resistance value of the seventh MR element 1 is a resistance value corresponding to the bias magnetic field H _B (hereinafter, referred to as a bias resistance value for convenience). R _B , and the resistance values of the sixth and eighth MR elements 1 adjacent to the seventh MR element 1 are different from the bias resistance value R _B. Specifically, the resistance value of the sixth MR element 1 is higher than the bias resistance value R _B , and the resistance value of the eighth MR element 1 is lower than the bias resistance value R _B.

Therefore, as shown in FIG.
The line connecting the plot points of the respective resistance values in Fig. 8 is descending to the right, and the final orientation of the direction of the external magnetic field H _E is shown in Fig. 8A.
It is understood that the direction is indicated by the arrow, that is, the easy axis direction of the seventh MR element 1, and the direction from the seventh MR element 1 to the fifteenth MR element 1.

On the other hand, in the external magnetic field H _E in the direction shown in FIG. 9A, the resistance value of the seventh MR element 1 shows the bias resistance value R _B, and the resistance value of the sixth MR element 1 is the bias value. It is lower than the resistance value R _{B, and the} resistance value of the eighth MR element 1 is higher than the bias resistance value R _B.

Therefore, in FIG. 9B, the three MR elements 1 described above are used.
The line connecting the plot points of the respective resistance values in FIG. 5 is rising to the right, and the final direction of the azimuth of the external magnetic field H _{E is} the direction indicated by the arrow in FIG. 9, that is, the easy axis of the seventh MR element 1. Direction, and from the 15th MR element 1 to the 7th M element
It can be seen that the direction is toward the R element 1.

Next, in the second method, the fourteenth, fifteenth and sixteenth consecutive three elements, which are 180 ° opposite to the MR element 1 selected in the first method, are provided.
This is a method of selecting one MR element 1 and detecting the respective resistance values to determine the azimuth.

First, in the external magnetic field H _E in the direction shown in FIG. 8A, the resistance value of the fifteenth MR element 1 shows the bias resistance value R _B, and the resistance value of the fourteenth MR element 1 is the bias value. 16th MR lower than resistance R _B
The resistance value of the element 1 is higher than the bias resistance value R _B.

Therefore, as shown in FIG.
The line connecting the plot points of the respective resistance values in the direction of rising is to the right. In this case, since the directions of the bias magnetic fields R _B of the MR elements 1 selected by the first method are different by 180 °, the external magnetic field H _E The final orientation of the azimuth is
It can be seen that it is the direction indicated by the arrow A, that is, the direction of the easy axis of the fifteenth MR element 1, and the direction from the seventh MR element 1 to the fifteenth MR element 1.

On the other hand, in the external magnetic field H _E in the direction shown in FIG. 9, the resistance value of the 15th MR element 1 shows the bias resistance value R _B, and the resistance value of the 14th MR element 1 is
It is higher than the bias resistance value R _{B, and the} resistance value of the 16th MR element 1 is lower than the bias resistance value R _B.

Therefore, in FIG. 9B, the three MR elements 1 described above are used.
The line connecting the plot points of the respective resistance values in Fig. 9 is downwards to the right, and the final orientation of the direction of the external magnetic field H _E is shown in Fig. 9A.
It is understood that the direction is indicated by the arrow, that is, the direction of the easy axis of the fifteenth MR element 1, and the direction from the fifteenth MR element 1 to the seventh MR element 1.

Next, the third method is a method in which the first method and the second method are used in combination. In this case, since the double check is performed, there is no error in azimuth determination.

Next, in the fourth method, three consecutive MR elements 1 of the second, third and fourth are selected by the scanner device 6 shown in FIG. This is a method of detecting the resistance value and determining the azimuth.

First, in the external magnetic field H _E in the direction shown in FIG. 8A, the resistance value of the third MR element 1 is the magnetic field (zero).
The resistance value according to the above, that is, the resistance value shows the maximum value.
2nd and 4th M adjacent to the 1st MR element 1
The resistance value of the R element 1 is different from the above resistance value (maximum value),
Both are lower than the resistance value (maximum value).

Therefore, in FIG. 8B, the three MR elements 1 are
The line connecting the plot points of the respective resistance values in Draw a convex curve upward, and the final direction of the azimuth of the external magnetic field H _{E is} the direction indicated by the arrow in FIG. 8A, that is, the third MR element. It can be seen that the hard axis direction is 1 and the direction is opposite to the direction of the bias magnetic field H _B applied to the third MR element 1.

On the other hand, in the external magnetic field H _E in the direction shown in FIG. 9A, the resistance value of the third MR element 1 shows a resistance value (zero) corresponding to the saturation magnetic field, and this third MR element 1 The resistance values of the second and fourth MR elements 1 adjacent to each other are both higher than the resistance value (zero).

Therefore, in FIG. 9B, the above-mentioned three MR elements 1 are
The line connecting the plot points of the respective resistance values in Draw a downward convex curve, and the final direction of the azimuth of the external magnetic field H _{E is} the direction indicated by the arrow in FIG. 9A, that is, the third MR element. It can be seen that the direction is the hard axis 1 and is the same as the direction of the bias magnetic field H _B applied to the third MR element 1.

Next, the fifth method is the tenth and eleventh methods.
This is a method in which three consecutive MR elements, the twelfth and the twelfth, are selected with the scanner device 6 shown in FIG.

First, in the external magnetic field H _E in the direction shown in FIG. 8A, the resistance value of the eleventh MR element 1 shows a resistance value (zero) according to the saturation magnetic field, and the eleventh MR element 1 10th and 12th MR elements 1 adjacent to
The resistance value of is different from the resistance value (zero), and both are higher than the resistance value (zero).

Therefore, in FIG. 8B, the above-mentioned three MR elements 1 are
The line connecting the plot points of the respective resistance values in Draw a downward convex curve, and the final direction of the direction of the external magnetic field H _{E is} the direction indicated by the arrow in FIG. 8A, that is, the eleventh MR element. 1
It can be seen that it is in the hard axis direction and is in the same direction as the direction of the bias magnetic field H _B applied to the eleventh MR element 1.

On the other hand, in the external magnetic field H _E in the direction shown in FIG. 9A, the resistance value of the eleventh MR element 1 shows the resistance value (maximum value) corresponding to the magnetic field (zero).
2nd and 4th M adjacent to the 1st MR element 1
Both of the resistance values of the R element 1 are lower than the resistance value (maximum value).

Therefore, in FIG. 9B, the three MR elements 1
The line connecting the plot points of the respective resistance values in Draw a convex curve upward, and the final direction of the direction of the external magnetic field H _{E is} the direction indicated by the arrow in FIG. 9A, that is, the eleventh MR element. 1
It can be seen that the direction of the hard axis is the direction opposite to the direction of the bias magnetic field H _B applied to the eleventh MR element 1.

Next, the sixth method is a method in which the fourth method and the fifth method are used in combination. In this case, since double check is performed as in the case of the third method, there is no error in azimuth determination.

To summarize these methods, first, when the resistance values of the first to 16th MR elements 1 are detected, the line connecting the plot points of the resistance values is almost a sine curve. A corresponding curve will be drawn. And
As shown in the first to third methods, at least three MR elements 1 corresponding to the straight line portion are selected from the drawn curves, and the inclination of the line connecting the resistance values of the selected MR elements 1 is selected. The orientation of the external magnetic field H _E can be determined.

Further, at least three MR elements 1 corresponding to the inflection portion are selected from the curve conforming to the above-described sine curve, and the direction of the convexity of the line connecting the resistance values of the selected MR element 1 is selected. The direction of the external magnetic field H _E can be determined (fourth to sixth methods).

As described above, since the geomagnetic direction sensor according to the first embodiment has a structure in which a large number of MR elements 1 are arranged, the measurement magnetic field is measured at a large number of points, and the direction determination accuracy is high. Get higher Moreover, since a large number of MR elements 1 are arranged along the circumference of 360 ° and the respective easy axes are arranged along the radial direction of the circumference, the measured value of each MR element 1 Therefore, it is possible to determine the direction with high accuracy. Moreover, it is not necessary to take special measures against external noise and drift.

When actually determining the direction of the geomagnetism, the resistance value of each MR element 1 changed by the geomagnetism is electrically detected, and the detected value of each MR element 1 and the MR elements 1 adjacent to each other are detected. The azimuth of the geomagnetism is directly determined from the correlation between the resistance values of. In this case, it is possible to determine the azimuth of the geomagnetism from each resistance value of at least three consecutive MR elements 1.

As described above, in the geomagnetic direction sensor according to the first embodiment, the direction of the geomagnetism can be determined directly from the resistance value of the MR element 1. No circuit is required, and the overall configuration is downsized. Also, basically, the R-
Since the H characteristic does not require linearity, it is possible to improve the degree of freedom in design by being free from technical restrictions on the bias setting and the manufacturing method of the MR element 1.

The level of the sense current flowing through the MR element 1 is usually 0.1 to 1 mA, but in the case of this embodiment, it is sufficient to measure the resistance value of the MR element 1, so that one MR is used. The sense current flowing in the element 1 can be set to the order of .mu.A, and low power consumption can be achieved.

Next, the geomagnetic direction sensor according to the second embodiment will be described with reference to FIGS.

In the geomagnetic direction sensor according to the second embodiment, as shown in FIG. 10A, for example, a large number of strip-shaped MR elements 1 are prepared, and in this embodiment, nine MR elements 1 are prepared. 18 of the glass plate (not shown)
The sensor main body 2 is configured by arranging the easy axis direction along the radial direction of the semicircle at positions of respective angles evenly divided in the semicircular plane of 0 °. In this case, the division angle θ is θ = 180 ° / (n−1), and FIG.
In the example, since nine MR elements 1 are used, the division angle is 180 ° / 8 = 22.5 °.

Although not shown, a solenoid coil whose center in the winding direction is along the semicircular direction is wound around the sensor main body 2 which is evenly arranged in the 180 ° semicircular plane. A geomagnetic direction sensor according to the embodiment is configured. By supplying a bias current (direct current or alternating current) to this solenoid coil, a uniform bias magnetic field H _B is applied in the arrangement direction of the MR elements 1, that is, in the circumferential direction, as shown by the arrow in FIG. 10A.

When there is no external magnetic field (geomagnetism: H _E ), the state of each MR element 1 is only the bias magnetic field H _B which is uniform in the tangential direction (hard axis direction) of the semicircle to each MR element 1. Is applied, the resistance value of each MR element 1 is uniquely determined to be R _B.

Next, when there is an external magnetic field (geomagnetism: H _E ), the resistance value of each MR element 1 differs depending on the direction of the external magnetic field H _E.

[0080] As an example, as shown in FIG. 10A, when there is an arrow direction of the external magnetic field H _E, the hard axis direction component of the external magnetic field H _E applied to each MR element 1, the bias of each MR element 1 The combined magnetic field of the hard-axis direction component of the magnetic field H _B and the external magnetic field H _E , the resistance value of each MR element 1 and the voltage between both electrodes of each MR element 1 (terminal voltage) are shown in Table 3 below. The operating point (resistance value) on the RH characteristic of each MR element 1 is as shown in FIG. 10B.

[0081]

[Table 3]

Further, as shown in FIG. 11A, when there is an external magnetic field H _{E in the} direction opposite to that of FIG. 10A, the component in the hard axis direction of the external magnetic field H _E applied to each MR element 1 and each MR.
The bias magnetic field H _B in the element 1 and the composite magnetic field of the component in the hard axis direction of the external magnetic field H _E , the resistance value of each MR element 1 and the voltage between both electrodes of each MR element 1 (voltage between terminals) are as follows. As shown in Table 4, R of each MR element 1
The operating point (resistance value) on the −H characteristic is as shown in FIG. 11B.

[0083]

[Table 4]

When the resistance values of the first to ninth MR elements 1 are detected, the line connecting the plot points of the resistance values draws a curve substantially conforming to a sine curve. Then, as shown in the first to third methods, at least three Ms corresponding to the straight line portion from the drawn curve
The R element 1 is selected, and the orientation of the external magnetic field H _E can be determined from the inclination of the line connecting the resistance values of the selected MR element 1.

Further, at least three MR elements 1 corresponding to the inflection portion are selected from a curve conforming to the above-described sine curve, and the direction of the convexity of the line connecting the resistance values of the selected MR elements 1 is selected. The direction of the external magnetic field H _E can be determined (fourth to sixth methods).

Next, a geomagnetic direction sensor according to the third embodiment will be described with reference to FIGS. 12 and 13.

In the geomagnetic direction sensor according to the third embodiment, for example, as shown in FIG. 12A, a large number of strip-shaped MR elements 1, 11 in this embodiment, are prepared.
The element 1 is attached to a glass plate (not shown) as shown in FIG.
The sensor main body 2 is configured by arranging the easy axis direction along the radial direction of the arc at positions of respective angles that are evenly divided within the arc plane of 80 ° + 2θ. In this case, the division angle θ is θ = 180 ° / (n−3),
In the example of FIG. 12A, since 11 MR elements are used, the division angle is 180 ° / 8 = 22.5 °.

Although not shown in the drawings, a solenoid coil whose center in the winding direction is along the arc direction is wound around the sensor main body 2 which is evenly arranged in the arc plane of 180 ° + 2θ. The geomagnetic direction sensor is constructed. By applying a bias current (direct current or alternating current) to this solenoid coil, a uniform bias magnetic field H _B is applied in the arrangement direction of the MR elements 1, that is, in the arc direction, as shown by the arrow in FIG. 12A.

When there is no external magnetic field (geomagnetism: H _E ), the state of each MR element 1 is such that only a uniform bias magnetic field H _B is applied to each MR element 1 in the tangential direction of the arc (hard axis direction). Therefore, the resistance value of each MR element 1 is uniquely R
Determined by _B.

Next, when there is an external magnetic field (geomagnetism: H _E ), the resistance value of each MR element 1 differs depending on the direction of the external magnetic field H _E.

As an example, as shown in FIG.
When there is an external magnetic field H _{E in the} same direction as the direction of the bias magnetic field H _B applied to the th MR element 1, the operating point (resistance value) on the RH characteristic of each MR element 1 is shown in FIG. 12B.
It becomes as shown in.

Further, as shown in FIG. 13A, when there is an external magnetic field H _{E in the} direction opposite to that of FIG. 12A, the operating point (resistance value) on the RH characteristics of each MR element 1 is as shown in FIG. 13B. become.

When the resistance value of each of the first to eleventh MR elements 1 is detected, the line connecting the plot points of the resistance value draws a curve substantially conforming to a sine curve. Then, as shown in the first to third methods,
At least three MR elements 1 corresponding to the straight line portion are selected from the drawn curves, and the orientation of the external magnetic field H _E can be determined from the inclination of the line connecting the resistance values of the selected MR elements 1.

Further, at least three MR elements 1 corresponding to the inflection portion are selected from the curve conforming to the above-mentioned sine curve, and the direction of the convexity of the line connecting the resistance values of the selected MR element 1 is selected. The direction of the external magnetic field H _E can be determined (fourth to sixth methods).

The geomagnetic direction sensors according to the second embodiment and the third embodiment also have high azimuth determination accuracy and each MR element 1 as in the geomagnetic direction sensor according to the first embodiment.
There is a correlation between the measured values of, and it is possible to determine the direction with high accuracy. Moreover, it is not necessary to take special measures against external noise and drift.

Further, since the geomagnetic azimuth can be determined directly from the resistance value of the MR element 1, an auxiliary circuit such as a conventional vector synthesizing arithmetic circuit is not required, and the whole structure is miniaturized. Further, basically, the linearity is not required for the Δρ-H characteristic of the MR element.
The technical restrictions on the manufacturing method of the element 1 are released, and the degree of freedom in design can be improved.

In each of the above-mentioned first to third embodiments, each MR is
As a means for applying a bias magnetic field H _B to the element 1, a toroidal coil 3 having a center in the winding direction as a circumferential direction, a semicircular direction, or an arc direction is wound, and a bias current I0 is passed through the toroidal coil 3. Thus, the bias magnetic field H _B in the circumferential direction, the semicircular direction, and the arc direction is applied to each MR element 1, but in addition, as shown in FIG. The magnet 11 may be arranged to apply the bias magnetic field H _B to each MR element 1.

In this case, the magnet 1 is magnetized so that the magnetizing direction of the magnet 11 is a tangential direction of a circle, a semicircle, or an arc.
1 is arranged and a bias magnetic field H _B is applied to each MR element 1. In this configuration, the work of winding the toroidal coil and the supply of the bias current are not required, so that the structure is simplified and the power consumption can be reduced.

Further, in the above-mentioned first to third embodiments,
Although one MR element 1 is selected by the scanner device 6 and the resistance value of the selected MR element 1 is directly detected by the tester 7, other than that, as shown in FIG. The constant current source 12 may be connected to the MR device 1, a constant current I may be applied to the MR element 1 selected by the scanner device 6, and the terminal voltage V of the MR element 1 may be measured by the tester 7.

By the way, in each of the above-mentioned embodiments, the example in which a large number of MR elements 1 are arranged on the base glass on the circumference, the semicircle and the arc, respectively, is actually mounted as a sensor. In this case, it is desirable to have the following configuration.

That is, the structure of the geomagnetic direction sensor according to the second embodiment will be described as an example.
As shown in FIG. 18, a magnetic material having a high magnetic permeability has a flat surface, 1
A magnetic core 33 having a semicircular shape of 80 ° and having a number of winding grooves 31 corresponding to the number of MR elements 1 and a magnetic gap 32 communicating with the winding grooves 31 is prepared.
In the magnetic core 33, 180 magnetic gaps 32 are formed at equal intervals. The winding groove 31 is filled with a non-magnetic material 34.

Then, the MR element 1 is formed on each magnetic gap 32 of the magnetic core 33, and the winding 35 for applying the bias magnetic field H _B to the MR element 1 is further provided in each winding groove 31. And a lead-out end of the winding 35 is connected to a bias magnetic field generating AC power supply 36. Since the MR element 1 is formed on the magnetic gap 32, it is possible to employ a collective operation by a photolithography process.

Here, the gap length of the magnetic gap 32 provided in the magnetic core 33 is G0, the bias current flowing in the winding 35 is I0, and the resistance change of each MR element 1 in the magnetic field generated in each magnetic gap 32 is changed. Assuming that the magnetic field component in the direction of the hard axis that contributes to Hx is Hx, the relationship between this magnetic field component Hx and the bias current I0 is expressed by the following equation (3).

Hx≈N · I0 / G0 (3) Note that N is the number of turns of the winding 35.

Calculating the magnetic field component Hx by substituting numerical values, N = 150 turns, G0 = 1.0 mm, I0
= 30 mA and the magnetic core diameter R = 20 mm, the following equation (4) is obtained. At this time, the bias magnetic field is optimally 60 [Oe] from the RH characteristics.

Hx = 150 × 30 [mA] /1.0 [mm] ≈ 56 [Oe] ………… (4)

For comparison, as shown in FIG. 19, 180 MRs are formed on the base glass plate 41 formed in a plane semicircular shape.
The element 1 is arranged along a glass plate 41 on a semicircle at equal intervals to form a sensor body 42, and a toroidal coil 43 is wound around the sensor body 42. Try to find the magnetic field component.
This magnetic field component can be calculated by the following equation (5).

Hx ≈ N · I0 / 2πR ………… (5)

Specifically, when the same numerical values as above are substituted for the calculation, the following equation (6) is obtained. Hx = 150 × 30 [mA] / 2 × π × 20 [mm] = 3.98 [Oe] ............ (6)

From the above calculation example, a predetermined bias magnetic field (6
The magnitude of the bias current I0 supplied to obtain 0 [Oe] is smaller when the magnetic core 33 shown in FIGS. 16 to 18 is used than when the base glass plate 41 shown in FIG. 19 is used. It can be reduced to 1/14.

The above calculation example shows a case where the magnetic field component for one MR element 1 is calculated. In reality, since there are 180 MR elements 1, the following formula (7) is used for calculation.

Hx≈N · I0 / (n · G0) (7) Note that n represents the number of MR elements 1.

In this case, the bias current I0 is reduced to 1/17 as compared with that using the base glass plate 41.

Thus, as shown in FIGS. 16-18, the number of winding grooves 31 formed of a magnetic material having a high magnetic permeability in a semicircular plane and corresponding to the number of MR elements 1, When a magnetic core 33 having a magnetic gap 32 communicating with the winding groove 31 is prepared and the MR element 1 is formed on each magnetic gap 32 of the magnetic core 33 to form the sensor body, It is possible to employ collective work by a photolithography process, which improves workability and reduces variations in characteristics among the formed MR elements 1.

Moreover, the bias magnetic field H _{B is applied} to each MR element 1.
The level of the bias current I0 for applying the voltage can be significantly reduced, the circuit-like drift occurring in the sensor body can be effectively suppressed, and the power consumption is reduced in combination with the reduction of the sense current level. Is advantageous in reducing

Although the MR element is formed of the FeNi-based ferromagnetic film in each of the above embodiments, it may be formed of a CoNi-based ferromagnetic film. InSb, InAs, InAsP, GaA
The MR element may be composed of a magnetoelectric semiconductor element such as s, Si, or Ge.

In this case, as shown in FIG. 20, for example, the length n of the sensing portion is ~ 7 mm, the width w is 80 μm, and the thickness t is ~.
Au is attached to both ends of the 200 nm strip-shaped magnetoelectric semiconductor element 51.
By forming electrodes 52a and 52b consisting of
An R element is constructed. The bias magnetic field H _B and the external magnetic field component H _S that contributes to the resistance change are applied in the direction perpendicular to the plate surface of the magnetoelectric semiconductor element 51.

[0118]

As described above, according to the geomagnetic direction sensor of the present invention, a large number of magnetoresistive effect elements are arranged along an arc having a circumferential angle of 180 ° or more, and each easy axis has the above-mentioned arc. Since the sensor main body arranged along the radial direction of and the means for applying the bias magnetic field in the circumferential direction of the circular arc are provided, direct azimuth determination is possible,
Azimuth accuracy is high, and the number of circuit points can be reduced.
The ρ-H characteristic does not require linearity, which is advantageous in manufacturing.

Further, according to the geomagnetic direction sensor of the present invention, a magnetic material having a high magnetic permeability is formed in a plane 360 ° circumference or an arc shape having a circumference angle of 180 ° or more, and the magnetoresistive effect is obtained. The magnetoresistive element is formed on each magnetic gap of the magnetic core provided with a number of winding grooves corresponding to the number of elements and a magnetic gap communicating with the winding groove, and Since the winding for applying the bias magnetic field is wound around each of the magnetoresistive effect elements, it is possible to reduce the bias current necessary for generating the bias magnetic field, and the circuit drift. Can be suppressed.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing a sensor body in a first embodiment of a geomagnetic direction sensor according to the present invention.

FIG. 2 is a plan view schematically showing a state in which a toroidal coil is wound around the sensor body of the geomagnetic direction sensor according to the first embodiment.

FIG. 3 is a plan view showing an MR element used in the geomagnetic direction sensor according to the first embodiment.

FIG. 4 is an MR of the geomagnetic direction sensor according to the first embodiment.
It is a block diagram which shows the measuring method of the resistance value in an element.

FIG. 5 is an explanatory diagram showing vector analysis of resistance change when an external magnetic field is applied to the MR element.

FIG. 6 is a characteristic diagram showing changes in the resistance value of the MR element with respect to changes in the external magnetic field (or θ) (RH (ρ-H) characteristics).

FIG. 7 is a characteristic diagram showing characteristics when the RH (ρ-H) characteristics of the MR element are treated as linear characteristics.

FIG. 8A is a plan view showing a vector display of a relationship between a bias magnetic field component applied to each MR element of the geomagnetic direction sensor according to the first embodiment and an external magnetic field in the arrow direction, FIG. 9B shows R- of each MR element by the external magnetic field.
It is a characteristic view which shows the operating point (resistance value) on H characteristic.

FIG. 9A is a relationship between a bias magnetic field component applied to each MR element of the geomagnetic direction sensor according to the first embodiment and an external magnetic field in the arrow direction (direction opposite to the arrow direction in FIG. 8A). Is a plan view showing by vector representation, and FIG. 7B is a characteristic diagram showing operating points (resistance values) on the RH characteristics of each MR element due to the external magnetic field.

FIG. 10A is a plan view showing a vector display of a relationship between a bias magnetic field component applied to each MR element of the geomagnetic direction sensor according to the second embodiment and an external magnetic field in the arrow direction, FIG. 9B shows R of each MR element by the external magnetic field.
It is a characteristic view which shows the operating point (resistance value) on a -H characteristic.

FIG. 11A is a relationship between a bias magnetic field component applied to each MR element of the geomagnetic direction sensor according to the second embodiment and an external magnetic field in the arrow direction (direction opposite to the arrow direction in FIG. 10A). FIG. 2B is a plan view showing a vector of FIG.
FIG. 4 is a characteristic diagram showing operating points (resistance values) on the RH characteristics of each MR element due to the external magnetic field.

FIG. 12A is a plan view showing a vector display of a relationship between a bias magnetic field component applied to each MR element of the geomagnetic direction sensor according to the third embodiment and an external magnetic field in the arrow direction, FIG. 9B shows R of each MR element by the external magnetic field.
It is a characteristic view which shows the operating point (resistance value) on a -H characteristic.

13A is a relationship between a bias magnetic field component applied to each MR element of the geomagnetic direction sensor according to the second embodiment and an external magnetic field in the arrow direction (direction opposite to the arrow direction in FIG. 12A). FIG. 2B is a plan view showing a vector of FIG.
FIG. 4 is a characteristic diagram showing operating points (resistance values) on the RH characteristics of each MR element due to the external magnetic field.

FIG. 14 is a plan view of an essential part showing another configuration of a means for applying a bias magnetic field to each MR element (a strip-shaped magnet is arranged between each MR element).

FIG. 15 is a configuration diagram showing another example of the method of measuring the resistance value of each MR element.

FIG. 16 is a perspective view showing a geomagnetic direction sensor having a configuration in which MR elements are formed on each magnetic gap of a semicircular magnetic core having winding grooves and magnetic gaps for the number of MR elements.

FIG. 17 is a plan view showing a geomagnetic direction sensor having a configuration in which MR elements are formed on each magnetic gap of a semicircular magnetic core having winding grooves and magnetic gaps for the number of MR elements.

FIG. 18 shows a geomagnetic direction sensor having a structure in which MR elements are formed on each magnetic gap of a semicircular magnetic core having winding grooves and magnetic gaps for the number of MR elements. It is sectional drawing cut and shown along the passing center line.

FIG. 19 is a plan view showing an M-shaped base glass plate formed in a plane semicircular shape.
It is a top view which shows the geomagnetic direction sensor which has the structure which arranged the R element and wound the toroidal coil.

FIG. 20 is a perspective view showing a case where an MR element is composed of a magnetoelectric semiconductor element.

FIG. 21 is a plan view showing a magnet type geomagnetic direction sensor according to a conventional example.

FIG. 22 is a characteristic diagram showing resistance change characteristics (Δρ-H characteristics) of an ordinary MR element in use with respect to an external magnetic field.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 MR element 2 Sensor body 3 Toroidal coil 4a and 4b Electrode 5 Conductor wire 6 Scanner device 7 Tester 51 Magnetoelectric semiconductor element

Claims (2)

[Claims] 1. A plurality of magnetoresistive effect elements are 360 °.
A sensor body in which a circle or an arc having a circle angle of 180 ° or more and each easy axis are arranged in a radial direction of the circle or the arc, and a bias magnetic field in a tangential direction of the circle or the arc. A magnetic orientation sensor having a means for applying a magnetic field. 2. A high permeability magnetic material having a flat surface of 360 °
A magnetic core formed in a circular shape or in an arc shape having a circumferential angle of 180 ° or more and having a number of winding grooves corresponding to the number of the magnetoresistive effect elements and a magnetic gap communicating with the winding grooves. The magnetoresistive effect element is formed on each magnetic gap, and a winding for applying a bias magnetic field to each magnetoresistive effect element is wound around the winding groove. The geomagnetic direction sensor according to claim 1.