JPH09126780A - Magnetic direction sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of part items and the number of assembling steps by performing detection of the quantity of magnetism and the ratio of the amount of magnetism in X and Y axis directions of a three-dimensional stereoscopic space represented by X, Y and Z axes while taking the Z axis as the gravity direction of the earth, with one magnetoresistance element. SOLUTION: A bobbin is provided with a bias coil 4 and a bias coil 5 intersecting this coil and these coils are formed in such a manner that when currents are supplied to the coils 4 and 5, the directions of their biased magnetic fields take angles of 90 degrees to each other. The coil 4 is provided with an applied current oscillator 17, the coil 5 is provided with an applied current oscillator 18 and AC rectangular wave currents are supplied by one pulse alternately to the coils 4 and 5. Then, the output of a magnetoresistance element is detected in synchronization with the positive and negative timings of the AC rectangular wave currents, a difference between these is amplified by an amplifier circuit 10 including a bypass filter 9 and the magnetic sensor outputs of X and T axes are obtained. Each of these magnetic sensor output is inputted through an A/D converter 11 to a microcomputer 12, magnetic declination is calculated and a magnetic azimuth output 13 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic azimuth sensor using a magnetic sensor, and more particularly to a magnetic azimuth sensor and a magnetic azimuth sensor which are stable against a reduction in the number of parts and a change in ambient temperature or a change over time. Regarding measurement method.

[0002]

2. Description of the Related Art FIG. 3 is a principle diagram of a magnetic bearing sensor. The azimuth obtained by the magnetic azimuth sensor can be obtained from the magnetic quantity ratio of the X axis and the Y axis when the gravity direction on the earth is the Z axis. That is, in FIG. 3, the magnetic sensor 7 and the magnetic sensor 8 are arranged so as to be parallel to the X-axis and the Y-axis and orthogonal to each other, and the sensitivity and the offset voltage of the magnetic sensor are adjusted to be the same. .

At this time, a point where the output of the X-axis magnetic sensor reaches the maximum value V ₁ is set as an origin (azimuth angle θ = 0 degree), and X
When two magnetic sensors are rotated by an angle θ on the Y plane,
The sensor outputs of the magnetic sensor 7 and the magnetic sensor 8 on the X-axis and the Y-axis are represented by V _X and V _Y , respectively, and are expressed by the following equation.

V _X = V ₁ cos θ ····· V _Y = V ₁ sin θ ········· Therefore, in order to obtain the angle θ, the following calculation I do. θ = tan ⁻¹ (V _Y / V _X ) ... The angle θ is classified in the range shown in Table 1.

[0005]

As described above, the conventional magnetic direction sensor is
One magnetic sensor is arranged on each of the X-axis and the Y-axis, and the magnetic sensors are used after the sensitivity and the offset voltage of each magnetic sensor are adjusted to the same value. The azimuth calculation is performed by a circuit process.

[0007]

However, the conventional magnetic azimuth sensor requires two magnetic sensors as described above, and the sensitivity and offset voltage of each magnetic sensor are adjusted to the same value. It cannot be used unless it is used, and the assembly process is complicated. Further, there is a drawback that the reliability such as a temperature drift and a change with time also varies, and the difference in the variation appears as an error in the azimuth angle. Therefore, it is an object of the present invention to provide a magnetic azimuth sensor which has a reduced number of parts, has a simplified assembly process, is inexpensive, has no error in azimuth angle, and has high reliability.

[0008]

According to the present invention, a magnetic sensor detects the magnetic quantities of the X-axis and the Y-axis of a three-dimensional space represented by the three axes of X, Y and Z, where the direction of gravity on the earth is the Z-axis. Detected by
An amplifier circuit for amplifying the output of the magnetic sensor, an X-axis and a Y-axis
In a magnetic sensor having an arithmetic circuit for calculating the output ratio (Y / X) of the axes, and detecting the azimuth from the output ratio, the magnetic quantity and the magnetic quantity ratio of the X axis and the Y axis are detected by one magnetoresistive element. The magnetic azimuth sensor is characterized in that

According to the present invention, the magnetoresistive element has two bias coils for applying a bias magnetic field, and the two bias magnetic fields generated by the bias coils have an angle of 90 degrees with each other. In the above magnetic azimuth sensor, a coil is arranged.

The present invention is the above magnetic azimuth sensor, wherein the amplifier circuit is composed of an amplifier circuit including a high-pass filter.

The present invention is the above magnetic bearing sensor, wherein the arithmetic circuit is composed of a circuit including a microcomputer.

The present invention uses the same magnetoresistive element and time-divisionally applies a bias magnetic field having an angle of 90 degrees to each other to synchronize the output of the magnetoresistive element with the bias magnetic field. The magnetic azimuth measuring method is characterized in that the magnetic azimuth is measured by performing the following processing.

(Operation) In the present invention, one magnetoresistive element is used as the magnetic sensor, and two bias coils are arranged so that the directions of the bias magnetic fields applied to the magnetoresistive element are at 90 ° to each other. , And alternately apply one pulse of AC rectangular wave current to the two bias coils,
The output of the magnetoresistive element is detected in synchronism with the positive and negative timings of the AC rectangular wave current, and the difference is amplified by an amplifier circuit including a high-pass filter to obtain a uniaxial magnetic sensor output. A biaxial magnetic sensor is constructed by alternately applying an alternating rectangular wave current to the two bias coils.
The outputs of the biaxial magnetic sensors are input to a microcomputer to calculate the azimuth angle. As a result, the assembly process can be simplified relatively easily, and variations in the magnetic sensor output of each axis and changes over time can be eliminated.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a magnetoresistive element of a magnetic bearing sensor of the present invention. FIG. 1A is a plan view showing a state before winding a coil around the magnetoresistive element. b)
FIG. 4 is a plan view showing a state after winding a coil around a magnetoresistive element.

As shown in FIG. 1A, the magnetoresistive element 1
Is inserted into the bobbin 2 for winding, and the magnetoresistive element terminal 3 for the magnetoresistive element 1 is drawn out of the bobbin 2. Further, as shown in FIG. 1 (b), the bobbin 2 is provided with a bias coil 4 and a terminal pin 6 for the bias coil 5 which is orthogonal to the bias coil 4. Later, the terminal ends are soldered to the terminal pins 6.

The two bias coils are arranged in a cross shape, and each bias coil 4 and bias coil 5 are arranged.
When a current is applied to the
It is configured to have an angle of degrees.

FIG. 2 is a circuit block diagram of a magnetic direction sensor according to the present invention. As shown in FIG. 2, first, there are an applied current oscillator 17 of the bias coil 4 and an applied current oscillator 18 of the bias coil 5 which are arranged such that the directions of the bias magnetic fields generated with each other are 90 degrees. An alternating rectangular wave current is alternately passed through the bias coil 4 and the bias coil 5 pulse by pulse. Next, in synchronization with the positive and negative timings of the AC rectangular wave current, the output of the magnetoresistive element is detected, the difference is amplified by an amplifier circuit 10 including a high-pass filter 9, and the X-axis and Y-axis are detected. Obtain the magnetic sensor output of the shaft. The X-axis and Y-axis magnetic sensor outputs are input to the microcomputer 12 through the A / D converter 11, the azimuth angle is calculated, and the magnetic azimuth output 13 is obtained.

[0019]

As described above, according to the magnetic azimuth sensor of the present invention, two magnetic sensors are conventionally required, but the number is reduced to one, and the amplifier circuit and the like are also magnetic sensors. Since the number of parts is reduced to one, the number of parts and the number of assembling steps can be simplified. Furthermore, since it is unnecessary to adjust the sensitivity and offset voltage of the magnetic sensor,
The number of adjustment steps can be reduced.

Further, in the present invention, azimuth errors due to individual changes over time caused by using separate magnetic sensors are canceled by each other in order to obtain biaxial outputs with the same magnetic sensor. It has an advantage that it is not necessary to consider the azimuth calculation error due to, and it becomes possible to eliminate the variation of the magnetic sensor output of each axis and the change over time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a magnetoresistive element of a magnetic direction sensor of the present invention. FIG. 1A is a plan view showing a state before winding a coil around a magnetoresistive element. FIG. 1B is a plan view showing a state after winding a coil around the magnetoresistive element.

FIG. 2 is a circuit block diagram of a magnetic bearing sensor of the present invention.

FIG. 3 is a principle diagram of a magnetic direction sensor.

[Explanation of symbols]

 1 Magnetoresistive Element 2 Bobbin 3 Magnetoresistive Element Terminal 4, 5 Bias Coil 6 Terminal Pin 7, 8 Magnetic Sensor 9 High Pass Filter 10 Amplification Circuit 11 A / D Converter 12 Microcomputer 13 Magnetic Direction Output 17 Applied Current Oscillator of Bias Coil 4 18 Applied Current Oscillator of Bias Coil 5

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 43/08 G01R 33/06 R

Claims (5)

[Claims] 1. The Z-axis is the direction of gravity on the earth, and X, Y,
An X-axis and Y-axis magnetic quantity in a three-dimensional space represented by the three axes of Z is detected by a magnetic sensor, and an amplifier circuit for amplifying the output of the magnetic sensor and an output ratio of the X-axis and the Y-axis (Y / X). In a magnetic sensor for obtaining a direction from the output ratio, a magnetic direction sensor for detecting the X-axis and Y-axis magnetic amounts and the magnetic amount ratio is performed by one magnetoresistive element. . 2. The magnetoresistive element has two bias coils for applying a bias magnetic field, and the two bias coils are so arranged that the bias magnetic fields generated by the bias coils form an angle of 90 degrees with each other. The magnetic azimuth sensor according to claim 1, wherein the magnetic azimuth sensor is arranged. 3. The magnetic bearing sensor according to claim 1, wherein the amplifier circuit is composed of an amplifier circuit including a high-pass filter. 4. The magnetic direction sensor according to claim 1, wherein the arithmetic circuit is composed of a circuit including a microcomputer. 5. The same magnetoresistive element is used, and a bias magnetic field having an angle of 90 degrees is time-divided to the magnetoresistive element, and the output of the magnetoresistive element is processed in synchronization with the bias magnetic field. A magnetic azimuth measuring method characterized by being carried out.