WO2018173590A1 - Unité de capteur magnétique et procédé de détection de direction de champ magnétique l'utilisant - Google Patents

Unité de capteur magnétique et procédé de détection de direction de champ magnétique l'utilisant Download PDF

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WO2018173590A1
WO2018173590A1 PCT/JP2018/005903 JP2018005903W WO2018173590A1 WO 2018173590 A1 WO2018173590 A1 WO 2018173590A1 JP 2018005903 W JP2018005903 W JP 2018005903W WO 2018173590 A1 WO2018173590 A1 WO 2018173590A1
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magnetic field
magnetoresistive elements
magnetoresistive
magnetoresistive element
sensor unit
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PCT/JP2018/005903
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English (en)
Japanese (ja)
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高橋　大輔
西川　和宏
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日本電産株式会社
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  • the present invention relates to a magnetic sensor unit and a magnetic field direction detection method using the same.
  • a magnetic encoder is known as a device for detecting the rotational position of a rotor of a motor.
  • a magnetic sensor used in this magnetic encoder has a plurality of magnetoresistive elements which are arranged along at least two different directions and are magnetized by an external magnetic field. In the magnetic sensor, a change in the magnetic field direction of the external magnetic field is detected using the plurality of magnetoresistive elements.
  • the offset value is corrected using an amount of deviation from an ideal state in the output signal output from the magnetic sensor. .
  • the error of the output signal of the magnetic sensor includes a magnetic error.
  • This magnetic error is greatly influenced by the uniaxial magnetic anisotropy of the magnetoresistive element of the magnetic sensor. Further, the uniaxial magnetic anisotropy of the magnetoresistive element greatly affects the error of the output signal of the magnetic sensor.
  • the uniaxial magnetic anisotropy of the magnetoresistive element affects the magnetization direction of the magnetoresistive element that is magnetized by an external magnetic field. Therefore, since the resistance value of the magnetoresistive element changes, an output signal different from the actual output signal is output from the magnetoresistive element. Then, the magnetic sensor cannot detect the change in the magnetic field direction of the external magnetic field with high accuracy.
  • Patent Document 1 a method of correcting the output signal of the magnetic sensor using an offset value is conceivable.
  • it is necessary to obtain and set the offset value at the time of factory shipment of the magnetic encoder.
  • the offset value is different for each magnetic sensor, it is necessary to obtain and set the offset value for each magnetic sensor.
  • An object of the present invention is to provide a magnetic sensor unit capable of accurately detecting a magnetic field direction of an external magnetic field in consideration of the influence of the uniaxial magnetic anisotropy without using a correction value for each magnetic sensor, and a magnetic field direction using the magnetic sensor unit It is to provide a detection method.
  • a magnetic sensor unit includes a plurality of magnetoresistive elements that are arranged along at least two different directions and are magnetized by an external magnetic field, and a power source that applies a voltage to the plurality of magnetoresistive elements.
  • a voltage detection unit that detects a voltage at both ends of each magnetoresistive element when a voltage is applied to the plurality of magnetoresistive elements by the power supply unit, and a voltage detected by the voltage detection unit,
  • An arithmetic unit that obtains the magnetic field direction of the external magnetic field using the strength of the anisotropic magnetic field of each of the magnetoresistive elements.
  • the arithmetic unit is configured to determine the direction of the magnetic field of the external magnetic field and the magnetization direction of the magnetoresistive elements determined by the uniaxial magnetic anisotropy of the magnetoresistive elements, and the voltage detected by the voltage detector and the magnetoresistive elements.
  • a magnetization direction calculation unit that calculates using the resistance value of the element, and a magnetic field direction calculation unit that calculates the magnetic field direction of the external magnetic field using the magnetization direction and the strength of the anisotropic magnetic field.
  • a magnetic field direction detection method using a magnetic sensor unit includes a plurality of magnetoresistive elements arranged along at least two different directions and magnetized by an external magnetic field, and the plurality of magnetoresistive elements.
  • a magnetic field direction detection method using a magnetic sensor unit including a power supply unit that applies a voltage to the power supply unit.
  • the magnetic field direction detection method uses the voltage detection step of detecting each voltage at both ends of the plurality of magnetoresistive elements, the voltage detected in the voltage detection step, and the resistance value of each magnetoresistive element, A magnetization direction calculating step for obtaining a magnetization direction of a plurality of magnetoresistive elements, a magnetic field of the external magnetic field using the magnetization direction calculated in the magnetization direction calculating step and the strength of the anisotropic magnetic field of each magnetoresistive element And a magnetic field direction calculating step for obtaining the direction.
  • the influence of the external magnetic field is considered in consideration of the influence of the uniaxial magnetic anisotropy without using a correction value for each magnetic sensor.
  • the magnetic field direction can be detected with high accuracy.
  • FIG. 1 is a diagram schematically illustrating a configuration of a magnetic sensor unit according to the embodiment.
  • FIG. 2 is a diagram schematically showing a state in which the magnetic sensor is arranged with respect to the external magnetic field.
  • FIG. 3 is a circuit diagram of a circuit constituted by magnetoresistive elements.
  • FIG. 4 is a diagram showing the relationship between the magnetic field direction of the external magnetic field and the magnetization direction of the magnetoresistive element when the uniaxial magnetic anisotropy of the magnetoresistive element is in the X-axis direction.
  • FIG. 1 is a diagram schematically illustrating a configuration of a magnetic sensor unit according to the embodiment.
  • FIG. 2 is a diagram schematically showing a state in which the magnetic sensor is arranged with respect to the external magnetic field.
  • FIG. 3 is a circuit diagram of a circuit constituted by magnetoresistive elements.
  • FIG. 4 is a diagram showing the relationship between the magnetic field direction of the external magnetic field and the magnetization direction of the magnetoresist
  • FIG. 5 is a diagram showing the relationship between the magnetic field direction of the external magnetic field and the magnetization direction of the magnetoresistive element when the uniaxial magnetic anisotropy of the magnetoresistive element is in the Y-axis direction.
  • FIG. 6 is a diagram showing the relationship between the strength of the external magnetic field and the magnetization of the magnetoresistive element.
  • FIG. 7 is a flowchart showing the operation of the magnetic sensor unit.
  • FIG. 8 is a view corresponding to FIG. 1 of a magnetic sensor unit according to another embodiment.
  • FIG. 9 is a diagram corresponding to FIG. 3 of a circuit configured by magnetoresistive elements of a magnetic sensor unit according to another embodiment.
  • the direction of the magnetic field means the direction of the magnetic field generated from the N pole toward the S pole, and hereinafter, the direction of the magnetic field is also simply referred to as the magnetic field direction.
  • the magnetization direction means a direction in which the magnetoresistive element is magnetized by an external magnetic field. Specifically, the magnetization direction means the direction of the magnetic field from the north pole to the south pole in the magnetized magnetoresistive element.
  • FIG. 1 is a diagram schematically showing a configuration of a magnetic sensor unit 1 according to an embodiment of the present invention.
  • the magnetic sensor unit 1 includes a magnetic sensor 10 that can detect a change in an external magnetic field by a plurality of magnetoresistive elements 11 to 18.
  • the magnetic sensor 10 is disposed to face the magnet 2 that generates a magnetic field (external magnetic field), for example, and detects a change in the direction of the magnetic field generated by the magnet 2.
  • an arrow indicated by a broken line indicates a magnetic field generated by the magnet 2.
  • the magnetic sensor 10 capable of detecting a change in the magnetic field direction of the external magnetic field is used, for example, in a rotary encoder that detects the rotational position of the rotor of the motor.
  • the magnetic sensor unit 1 includes a magnetic sensor 10, a power supply unit 20, a voltage detection unit 30, and a calculation unit 40.
  • the magnetic sensor 10 has a plurality of magnetoresistive elements 11-18. That is, the magnetic sensor unit 1 has a plurality of magnetoresistive elements 11 to 18.
  • the magnetoresistive elements 11 to 18 are made of a ferromagnetic thin film metal such as NiFe. Therefore, the magnetoresistive elements 11 to 18 are magnetized by the external magnetic field.
  • the plurality of magnetoresistive elements 11 to 18 are disposed on a substrate (not shown), for example.
  • the plan view means a case where the surface (plane) of the substrate is viewed from the normal direction with respect to the surface.
  • the arrangement of the plurality of magnetoresistive elements 11 to 18 on the substrate is schematically shown in plan view. *
  • the plurality of magnetoresistive elements 11 to 18 include four pairs of magnetoresistive elements arranged in the same direction in plan view. That is, the magnetic sensor unit 1 of the present embodiment has eight magnetoresistive elements 11 to 18.
  • the eight magnetoresistive elements 11 to 18 are a pair of the first magnetoresistive element 11 and the eighth magnetoresistive element 18 aligned in the same direction and the pair of second magnetoresistive elements 12 and the seventh aligned in the same direction in plan view.
  • the magnetoresistive element 17 includes a pair of third and sixth magnetoresistive elements 13 and 16 arranged in the same direction, and a pair of fourth and fifth magnetoresistive elements 14 and 15 arranged in the same direction.
  • the white arrows in the magnetoresistive elements 11 to 18 in FIG. 1 mean the direction of uniaxial magnetic anisotropy of the magnetoresistive elements 11 to 18. *
  • the pair of fourth magnetoresistive elements 14 and fifth magnetoresistive elements 15 are arranged along different directions in plan view. That is, the direction in which the pair of first magnetoresistive elements 11 and the eighth magnetoresistive element 18 are arranged, the direction in which the pair of second magnetoresistive elements 12 and the seventh magnetoresistive element 17 are arranged, and the pair of third magnetoresistive elements 13.
  • the direction in which the sixth magnetoresistive elements 16 are arranged and the direction in which the pair of fourth magnetoresistive elements 14 and the fifth magnetoresistive elements 15 are arranged are different directions in plan view.
  • the interval in each direction described above is 45 degrees in plan view.
  • the direction in which the pair of first magnetoresistive element 11 and the eighth magnetoresistive element 18 are aligned and the direction in which the pair of third magnetoresistive element 13 and the sixth magnetoresistive element 16 are aligned are 45 in plan view. Varies.
  • the direction in which the pair of third magnetoresistive element 13 and the sixth magnetoresistive element 16 are arranged and the direction in which the pair of second magnetoresistive element 12 and the seventh magnetoresistive element 17 are arranged differ by 45 degrees in plan view.
  • the direction in which the pair of second magnetoresistive elements 12 and the seventh magnetoresistive element 17 are arranged and the direction in which the pair of fourth magnetoresistive elements 14 and the fifth magnetoresistive element 15 are arranged differ by 45 degrees in plan view.
  • the direction in which the pair of fourth magnetoresistive elements 14 and the fifth magnetoresistive element 15 are arranged and the direction in which the pair of first magnetoresistive elements 11 and the eighth magnetoresistive element 18 are arranged differ by 45 degrees in plan view.
  • the direction in which the pair of first magnetoresistive elements 11 and the eighth magnetoresistive element 18 are arranged and the direction in which the pair of second magnetoresistive elements 12 and the seventh magnetoresistive element 17 are arranged differ by 90 degrees in plan view.
  • the direction in which the pair of third magnetoresistive elements 13 and the sixth magnetoresistive element 16 are arranged and the direction in which the pair of fourth magnetoresistive elements 14 and the fifth magnetoresistive element 15 are arranged differ by 90 degrees in plan view. That is, the plurality of magnetoresistive elements 11 to 18 include magnetoresistive elements arranged along two directions orthogonal to each other in plan view. *
  • two magnetoresistive elements 11 to 18 two magnetoresistive elements arranged along two different directions in plan view are electrically connected in series. Specifically, of the first magnetoresistive element 11 to the eighth magnetoresistive element 18, two magnetoresistive elements different from each other by 90 degrees in a plan view are electrically connected in series. *
  • first magnetoresistive element 11 and the second magnetoresistive element 12 are electrically connected in series.
  • the third magnetoresistive element 13 and the fourth magnetoresistive element 14 are electrically connected in series.
  • the fifth magnetoresistive element 15 and the sixth magnetoresistive element 16 are electrically connected in series.
  • the seventh magnetoresistive element 17 and the eighth magnetoresistive element 18 are electrically connected in series. *
  • the two magnetoresistive elements electrically connected in series are electrically connected in parallel with each other. That is, the first magnetoresistive element 11 and the second magnetoresistive element 12, the third magnetoresistive element 13 and the fourth magnetoresistive element 14, the fifth magnetoresistive element 15 and the sixth magnetoresistive element 16, and the seventh magnetic resistance.
  • the resistance element 17 and the eighth magnetoresistance element 18 are electrically connected in parallel.
  • the circuit 50 shown in FIG. 3 is constituted by the eight magnetoresistive elements 11 to 18. *
  • R 1 to R 8 in FIGS. 1 and 3 are resistance values of the first magnetoresistive element 11 to the eighth magnetoresistive element 18, respectively.
  • R 1 is the resistance value of the first magnetoresistive element 11
  • R 2 is the resistance value of the second magnetoresistive element 12
  • R 3 is the resistance value of the third magnetoresistive element 13
  • R 4 is the resistance value of the fourth magnetoresistive element 14.
  • R 5 is the resistance value of the fifth magnetoresistive element
  • R 6 is the resistance value of the sixth magnetoresistive element 16
  • R 7 is the resistance value of the seventh magnetoresistive element 17.
  • R 8 is the resistance value of the eighth magnetoresistive element 18.
  • R 1 R 8 is represented by the following formula.
  • a current flows through the first magnetoresistive element 11 and the eighth magnetoresistive element 18 in the X-axis direction, and the second magnetoresistive element 12 and the seventh magnetoresistive element 17 flow with respect to the X axis in plan view.
  • a current flows in the direction of 90 degrees, that is, the Y-axis direction, and a current flows in the third magnetoresistive element 13 and the sixth magnetoresistive element 16 in a direction of 45 degrees with respect to the X axis in plan view.
  • a current flows through the resistance element 14 and the fifth magnetoresistance element 15 in a direction of 135 degrees with respect to the X axis in a plan view.
  • R 1 R 0 ⁇ R sin 2 ( ⁇ )
  • R 2 R 0 ⁇ R sin 2 ( ⁇ / 2 ⁇ )
  • R 3 R 0 - ⁇ Rsin 2 ( ⁇ / 4- ⁇ )
  • R 4 R 0 ⁇ R sin 2 ( ⁇ / 4 + ⁇ )
  • R 5 R 0 ⁇ R sin 2 ( ⁇ / 4 + ⁇ )
  • R 6 R 0 ⁇ R sin 2 ( ⁇ / 4 ⁇ )
  • R 7 R 0 ⁇ Rsin 2 ( ⁇ / 2 ⁇ )
  • R 8 R 0 ⁇ R sin 2 ( ⁇ )
  • R 0 is the resistance value of the magnetoresistive elements 11 to 18 in the absence of a magnetic field
  • ⁇ R is the change amount of the resistance value of the magnetoresistive elements 11 to 18 when the external magnetic field changes.
  • the power supply unit 20 applies a predetermined voltage Vp to the circuit 50. That is, the power supply unit 20 applies a predetermined voltage Vp to each of two magnetoresistive elements connected in series. That is, the power supply unit 20 applies a predetermined voltage Vp to the first magnetoresistive element 11 and the second magnetoresistive element 12 connected in series. The power supply unit 20 applies a predetermined voltage Vp to the third magnetoresistive element 13 and the fourth magnetoresistive element 14 connected in series. The power supply unit 20 applies a predetermined voltage Vp to the fifth magnetoresistive element 15 and the sixth magnetoresistive element 16 connected in series. The power supply unit 20 applies a predetermined voltage Vp to the seventh magnetoresistive element 17 and the eighth magnetoresistive element 18 connected in series. *
  • the voltage detector 30 detects an intermediate potential between two magnetoresistive elements connected in series. That is, the voltage detection unit 30 includes an intermediate potential V B ⁇ between the first magnetoresistive element 11 and the second magnetoresistive element 12, an intermediate potential V A ⁇ between the third magnetoresistive element 13 and the fourth magnetoresistive element 14, intermediate potential V a + of the fifth magneto resistance element 15 and the sixth magneto resistance element 16, to detect respective intermediate voltage V B + of the seventh magnetoresistance element 17 and the eighth magnetoresistance element 18.
  • the voltage detector 30 detects the difference between these intermediate potentials (V B + ⁇ V B ⁇ , V A + ⁇ V A ⁇ ). As a result, the voltage across the magnetoresistive elements 11 to 18 can be detected easily and accurately.
  • the calculation unit 40 determines the voltages at both ends of the magnetoresistive elements 11 to 18 detected by the voltage detecting unit 30, the resistance values of the magnetoresistive elements 11 to 18, and the strength of the anisotropic magnetic field of the magnetoresistive elements 11 to 18. Is used to determine the magnetic field direction of the external magnetic field.
  • the calculation unit 40 includes a magnetization direction calculation unit 41 and a magnetic field direction calculation unit 42. *
  • the magnetization direction calculator 41 calculates the magnetization directions of the magnetoresistive elements 11 to 18 determined by the magnetic field direction of the external magnetic field and the uniaxial magnetic anisotropy of the magnetoresistive elements 11 to 18.
  • the magnetization direction calculating unit 41 uses the voltages at both ends of the magnetoresistive elements 11 to 18 detected by the voltage detecting unit 30 and the resistance values of the magnetoresistive elements 11 to 18 as the magnetization directions of the magnetoresistive elements 11 to 18.
  • the magnetoresistive elements 11 to 18 are magnetized by the external magnetic field. However, since the magnetoresistive elements 11 to 18 have uniaxial magnetic anisotropy, the magnetization directions of the magnetoresistive elements 11 to 18 are affected by the uniaxial magnetic anisotropy. *
  • FIG. 4 and 5 show the relationship between the magnetic field direction of the external magnetic field, the magnetization directions of the magnetoresistive elements 11 to 18, and the uniaxial magnetic anisotropy of the magnetoresistive elements 11 to 18.
  • FIG. 4 schematically shows the relationship between the magnetic field direction of the external magnetic field and the magnetization Ms direction of the magnetoresistive elements 11 to 18 when the uniaxial magnetic anisotropy K of the magnetoresistive elements 11 to 18 is in the X-axis direction.
  • FIG. 5 schematically shows the relationship between the magnetic field direction of the external magnetic field and the magnetization Ms direction of the magnetoresistive elements 11 to 18 when the uniaxial magnetic anisotropy K of the magnetoresistive elements 11 to 18 is in the Y-axis direction. Show. *
  • the uniaxial magnetic anisotropy K of the magnetoresistive elements 11 to 18 affects the direction of magnetization Ms (magnetization direction) of the magnetoresistive elements 11 to 18 magnetized by the external magnetic field. . *
  • the resistance values R 1 and R 8 of the first magnetoresistive element 11 and the eighth magnetoresistive element 18 are expressed by the following (Expression 1) and (Expression 2).
  • ⁇ 1 is an angle formed by the X axis and the magnetization direction of the first magnetoresistive element 11.
  • R 1 R 0 ⁇ R sin 2 ( ⁇ 1 )
  • R 8 R 0 ⁇ R sin 2 ( ⁇ 1 )
  • the resistance values R 4 and R 5 of the fourth magnetoresistive element 14 and the fifth magnetoresistive element 15 are expressed by the following (Expression 3) and (Expression 4).
  • R 5 R 0 ⁇ R sin 2 ( ⁇ / 4 + ⁇ 1 )
  • the resistance values R 2 and R 7 of the second magnetoresistive element 12 and the seventh magnetoresistive element 17 are expressed by the following expressions (Expression 5) and (Expression 6).
  • ⁇ 2 is an angle formed by the X axis and the direction of the magnetization Ms of the first magnetoresistive element 11.
  • R 2 R 0 ⁇ R sin 2 ( ⁇ / 2 ⁇ 2 )
  • R 7 R 0 ⁇ R sin 2 ( ⁇ / 2 ⁇ 2 )
  • the resistances R 3 and R 6 of the third magnetoresistive element 13 and the sixth magnetoresistive element 16 are expressed by the following (Expression 7) and (Expression 8).
  • R 6 R 0 ⁇ R sin 2 ( ⁇ / 4 ⁇ 2 )
  • the resistance values R 1 to R 8 in the equations (Equation 1) to (Equation 8) described above are influenced by the uniaxial magnetic anisotropy of the magnetization of the magnetoresistive elements 11 to 18 by the external magnetic field. It is the resistance value when receiving.
  • the magnetization direction calculation unit 41 converts the intermediate potentials V B ⁇ , V B + , V A ⁇ , V A + (or intermediate voltages V B , V A ) detected by the voltage detection unit 30 into the following (formula 9) and ( By substituting into Equation 10), ⁇ 1 and ⁇ 2 are obtained.
  • the relationship between the magnetization directions ⁇ 1 and ⁇ 2 can be obtained by substituting the expressions (Expression 1) to (Expression 8) described above for R 1 to R 8. The formula is obtained. (Formula 9) (Formula 10)
  • the magnetic field direction calculation unit 42 uses the ⁇ 1 and ⁇ 2 calculated by the magnetization direction calculation unit 41 and the intensity of the anisotropic magnetic field of the magnetoresistive elements 11 to 18, that is, ⁇ in FIG. 4 and FIG. Obtain the magnetic field direction of the external magnetic field.
  • ⁇ is the angle of the magnetic field direction of the external magnetic field with respect to the direction of current flowing in the magnetoresistive elements 11 to 18 (current direction).
  • the strength of the anisotropic magnetic field means the strength of the magnetic field when the magnetization is saturated by applying an external magnetic field in the magnetization difficulty direction in the magnetoresistive elements 11 to 18.
  • the strength of the anisotropic magnetic field is the strength Ha of the magnetic field when the magnetization reaches the saturation magnetization Ms when the magnetoresistive elements 11 to 18 are magnetized in the magnetization difficult direction.
  • the strength of the anisotropic magnetic field can be obtained by actual measurement, for example. *
  • the energy F per unit volume generated in the magnetoresistive elements 11 to 18 magnetized by the external magnetic field is obtained by the following equation in consideration of the magnetic anisotropy energy and the energy of the external magnetic field.
  • F Ksin 2 ( ⁇ ) ⁇ MsH cos ( ⁇ )
  • the magnetic field direction ⁇ of the external magnetic field can be obtained using the converted magnetic field h and the magnetization directions ⁇ 1 and ⁇ 2 .
  • the converted magnetic field h is determined by the strength H of the external magnetic field and the strength Ha of the anisotropic magnetic field. Therefore, if the value Ha of the anisotropic magnetic field and the magnetization directions ⁇ 1 and ⁇ 2 are determined, the magnetic field direction ⁇ of the external magnetic field can be obtained.
  • the magnetic field direction calculation unit 42 calculates the magnetic field direction ⁇ of the external magnetic field by substituting the value Ha of the anisotropic magnetic field and the magnetization directions ⁇ 1 and ⁇ 2 into the above (Equation 13).
  • the magnetic field direction calculation unit 42, the magnetization direction theta 1, with one value of theta 2 may calculate the magnetic field direction ⁇ of the external magnetic field, the magnetization direction theta 1, both theta 2
  • the average value thereof may be used as the magnetic field direction of the external magnetic field.
  • the plurality of magnetoresistive elements 11 to 18 of the magnetic sensor unit 1 each have uniaxial magnetic anisotropy. Therefore, when the plurality of magnetoresistive elements 11 to 18 are magnetized by the external magnetic field, they are magnetized in a direction different from the magnetic field direction of the external magnetic field. Therefore, even if the magnetization directions of the magnetoresistive elements 11 to 18 of the magnetic sensor unit 1 are detected, the magnetic field direction of the external magnetic field cannot be obtained with high accuracy.
  • the magnetization directions ⁇ 1 and ⁇ 2 of the magnetoresistive elements 11 to 18 magnetized by the external magnetic field and the intensity Ha of the anisotropic magnetic field of the magnetoresistive elements 11 to 18 are obtained.
  • the magnetic field direction ⁇ of the external magnetic field can be obtained in consideration of the uniaxial magnetic anisotropy of the magnetoresistive elements 11 to 18.
  • the magnetic field direction ⁇ of the external magnetic field that takes into account the uniaxial magnetic anisotropy of the magnetoresistive elements 11 to 18 can be obtained by calculation. Therefore, unlike the prior art, there is no need to prepare a correction value considering the uniaxial magnetic anisotropy of the magnetoresistive elements 11-18.
  • the magnetic field direction ⁇ of the external magnetic field can be easily and accurately detected using the plurality of magnetoresistive elements 11 to 18.
  • the plurality of magnetoresistive elements 11 to 18 are magnetoresistive elements arranged along two directions orthogonal to each other in plan view (for example, the first magnetoresistive element 11 and the second magnetoresistive element 12). including.
  • the magnetic field direction ⁇ of the external magnetic field can be detected with high accuracy using the two magnetoresistive elements arranged along the two orthogonal directions. That is, by using the two magnetoresistive elements, the relationship between the magnetic field direction ⁇ of the external magnetic field and the magnetization directions ⁇ 1 and ⁇ 2 of the two magnetoresistive elements can be defined by an equation using a trigonometric function. Therefore, by using this equation, the magnetic field direction ⁇ of the external magnetic field in consideration of the uniaxial magnetic anisotropy of the magnetoresistive elements 11 to 18 can be accurately obtained by calculation.
  • FIG. 7 is a flowchart showing the operation of the magnetic sensor unit 1.
  • step S1 the voltage detector 30 detects the voltages across the magnetoresistive elements 11 to 18. That is, the voltage detection unit 30 causes the intermediate potential V B ⁇ between the first magnetoresistive element 11 and the second magnetoresistive element 12, the intermediate potential V A ⁇ between the third magnetoresistive element 13 and the fourth magnetoresistive element 14, intermediate potential V a + of the fifth magneto resistance element 15 and the sixth magnetoresistance element 16, a seventh magnetoresistance element 17 an intermediate potential V B + the eighth magnetoresistance element 18, respectively detected. Specifically, the voltage detector 30 detects the voltage across the magnetoresistive elements 11 to 18 by detecting the difference between these intermediate potentials (V B + ⁇ V B ⁇ , V A + ⁇ V A ⁇ ). can do.
  • step S2 the magnetization direction calculation unit 31 of the calculation unit 40 calculates ⁇ 1 and ⁇ 2 from the following equations using the voltages acting on both ends of the magnetoresistive elements 11 to 18 detected in step S1. To do.
  • the following expressions are (Expression 9) and (Expression 10) described above. (Formula 9) (Formula 10)
  • ⁇ is obtained from the following equation using ⁇ 1 and ⁇ 2 obtained in step S2 and the strength Ha of the anisotropic magnetic field obtained in advance.
  • the magnetic field direction ⁇ of the external magnetic field with respect to the current direction of the current flowing through the magnetoresistive elements 11 to 18 can be obtained. Therefore, the magnetic field direction ⁇ of the external magnetic field is calculated using the voltages at both ends of the magnetoresistive elements 11 to 18 detected by the voltage detector 30 and the strength Ha of the anisotropic magnetic field of the magnetoresistive elements 11 to 18. it can. *
  • step S1 corresponds to a voltage detection step.
  • step S2 corresponds to a magnetization direction calculation step.
  • Step S3 corresponds to a magnetic field direction calculation step.
  • the magnetic sensor unit 1 has eight magnetoresistive elements 11 to 18.
  • the magnetic sensor unit should just have the magnetoresistive element arrange
  • FIG. 8 schematically shows a configuration of a magnetic sensor unit 101 including four magnetoresistive elements 11, 12, 17, and 18.
  • the magnetic sensor unit 101 includes a magnetic sensor 110 that can detect a change in an external magnetic field by a plurality of magnetoresistive elements 11, 12, 17, and 18.
  • the plurality of magnetoresistive elements 11, 12, 17, and 18 include two pairs of magnetoresistive elements arranged in the same direction in plan view. That is, the four magnetoresistive elements 11, 12, 17, and 18 are a pair of second magnetic elements aligned in the same direction as the pair of first and eighth magnetoresistive elements 11 and 18 aligned in the same direction in plan view.
  • the resistor element 12 and the seventh magnetoresistive element 17 are included.
  • the pair of first magnetoresistive element 11 and the eighth magnetoresistive element 18 and the pair of second magnetoresistive element 12 and the seventh magnetoresistive element 17 are respectively arranged along different directions in plan view. In the magnetic sensor unit 101, the interval in each direction described above is 90 degrees in plan view. *
  • the first magnetoresistive element 11 and the second magnetoresistive element 12 are electrically connected in series.
  • the seventh magnetoresistive element 17 and the eighth magnetoresistive element 18 are electrically connected in series.
  • the first magnetoresistive element 11 and the second magnetoresistive element 12, and the seventh magnetoresistive element 17 and the eighth magnetoresistive element 18 are electrically connected in parallel.
  • the circuit 150 shown in FIG. 9 is configured by the four magnetoresistive elements 11, 12, 17, and 18.
  • R 1 , R 2 , R 7 , and R 8 in FIGS. 8 and 9 are the first magnetoresistive element 11, the second magnetoresistive element 12, the seventh magnetoresistive element 17, and the eighth magnetoresistive element 18, respectively. Resistance value.
  • R 1 , R 2 , R 7 , and R 8 are the same as (Equation 1), (Equation 5), (Equation 6), (Equation) of the embodiment. 2).
  • Voltage detector 30 detects the first magnetoresistance element 11 an intermediate potential V B of the second magnetoresistance element 12, a seventh magnetoresistance element 17 an intermediate potential V A of the eighth magnetoresistance element 18, respectively.
  • the magnetization direction calculation unit 41 obtains ⁇ 1 and ⁇ 2 by substituting the intermediate potentials V B and V A detected by the voltage detection unit 30 into the following (Equation 14) and (Equation 15), respectively.
  • R 1 , R 2 , R 7 , R 8 are represented by the above (Formula 1), (Formula 5), (Formula 6), and (Formula 2), respectively.
  • the relational expression of the magnetization directions ⁇ 1 and ⁇ 2 can be obtained.
  • the magnetic field direction calculation unit 42 substitutes the value of the anisotropic magnetic field intensity Ha and the magnetization directions ⁇ 1 and ⁇ 2 obtained by the magnetization direction calculation unit 41 into (Equation 13) of the above embodiment.
  • the magnetic field direction ⁇ of the external magnetic field is calculated.
  • the magnetic field direction ⁇ of the external magnetic field can be obtained in consideration of the uniaxial magnetic anisotropy of each of the magnetoresistive elements 11, 12, 17, and 18.
  • the magnetic sensor unit 1 has four pairs of magnetoresistive elements arranged in the same direction in plan view.
  • the magnetic sensor unit may have only the first magnetoresistive element 11, the second magnetoresistive element 12, the third magnetoresistive element 13, and the fourth magnetoresistive element 14.
  • the magnetic field direction ⁇ of the external magnetic field can be calculated by the same method as in the above embodiment.
  • the magnetic sensor unit 1 detects an intermediate potential between a pair of magnetoresistive elements electrically connected in series in order to detect voltages across the magnetoresistive elements 11 to 18.
  • the magnetic sensor unit may detect the voltages at both ends of the magnetoresistive elements 11 to 18 by another configuration, for example, as long as the voltage at both ends of the magnetoresistive elements 11 to 18 can be detected.
  • the magnetization directions ⁇ 1 and ⁇ 2 of the magnetoresistive elements 11 to 18 and the magnetic field direction ⁇ of the external magnetic field are defined with reference to the X axis shown in FIG.
  • the magnetization directions ⁇ 1 and ⁇ 2 and the magnetic field direction ⁇ may be defined with reference to axes other than the X axis.
  • the present invention is applicable to a magnetic sensor unit having a plurality of magnetoresistive elements.

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  • Measuring Magnetic Variables (AREA)

Abstract

[Problème] Proposer une unité de capteur magnétique et un procédé de détection de direction de champ magnétique l'utilisant capables de détecter avec précision la direction d'un champ magnétique externe sans utiliser de valeurs de correction pour chaque capteur magnétique et tout en prenant en compte l'influence de l'anisotropie magnétique uniaxiale d'éléments magnétorésistifs. [Solution] L'unité de capteur magnétique 1 de l'invention est pourvue d'une pluralité d'éléments magnétorésistifs 11-18 agencés le long d'au moins deux directions différentes et aimantés par un champ magnétique externe et d'une unité de calcul 40 servant à déterminer la direction du champ magnétique externe à l'aide des tensions entre les extrémités des éléments magnétorésistifs 11-18 et les intensités des champs magnétiques anisotropes des éléments magnétorésistifs 11-18. L'unité de calcul 40 est pourvue d'une unité de calcul de direction d'aimantation 41 pour utiliser les tensions et les valeurs de résistance des éléments magnétorésistifs 11-18 afin de déterminer les directions d'aimantation des éléments magnétorésistifs 11-18 et d'une unité de calcul de direction de champ magnétique 42 pour utiliser les directions de champ magnétique et les intensités des champs magnétiques anisotropes afin de calculer la direction du champ magnétique externe.
PCT/JP2018/005903 2017-03-23 2018-02-20 Unité de capteur magnétique et procédé de détection de direction de champ magnétique l'utilisant WO2018173590A1 (fr)

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JP2002350136A (ja) * 2001-05-22 2002-12-04 Hitachi Metals Ltd 方位計
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WO2010113820A1 (fr) * 2009-03-30 2010-10-07 日立金属株式会社 Dispositif de détection d'angle de rotation
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3024218B2 (ja) * 1994-08-23 2000-03-21 松下電器産業株式会社 磁気信号検出装置
JP2002350136A (ja) * 2001-05-22 2002-12-04 Hitachi Metals Ltd 方位計
JP2005197364A (ja) * 2004-01-05 2005-07-21 Mitsubishi Electric Corp 磁界検出素子、磁界検出器、磁界検出方法および磁界検出素子の製造方法
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JP2008209311A (ja) * 2007-02-27 2008-09-11 Tdk Corp 磁気センサ、磁気方位センサ、磁界検出方法および磁気方位検出方法
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