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WO2018173590A1 - Magnetic sensor unit and magnetic field direction detection method using same - Google Patents

Magnetic sensor unit and magnetic field direction detection method using same Download PDF

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Publication number
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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Prior art keywords
magnetic field
magnetoresistive elements
magnetoresistive
magnetoresistive element
sensor unit
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PCT/JP2018/005903
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French (fr)
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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Publication of WO2018173590A1 publication Critical patent/WO2018173590A1/en

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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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Abstract

[Problem] To provide a magnetic sensor unit and magnetic field direction detection method using the same that are capable of accurately detecting the magnetic field direction of an external magnetic field without using correction values for each magnetic sensor and while taking into consideration the influence of the uniaxial magnetic anisotropy of magnetoresistive elements. [Solution] This magnetic sensor unit 1 is provided with a plurality of magnetoresistive elements 11-18 that are arranged along at least two different directions and are magnetized by an external magnetic field and a calculation unit 40 for determining the magnetic field direction of the external magnetic field using the voltages between the ends of the magnetoresistive elements 11-18 and the strengths of the anisotropic magnetic fields of the magnetoresistive elements 11-18. The calculation unit 40 is provided with a magnetization direction calculation unit 41 for using the voltages and the resistance values of the magnetoresistive elements 11-18 to determine the magnetization directions of the magnetoresistive elements 11-18 and a magnetic field direction calculation unit 42 for using the magnetic field directions and the strengths of the anisotropic magnetic fields to calculate the magnetic field direction of the external magnetic field.

Description

磁気センサユニット及びそれを用いた磁界方向検出方法Magnetic sensor unit and magnetic field direction detection method using the same
本発明は、磁気センサユニット及びそれを用いた磁界方向検出方法に関する。 The present invention relates to a magnetic sensor unit and a magnetic field direction detection method using the same.
例えばモータの回転子の回転位置を検出する装置として、磁気式エンコーダが知られている。この磁気式エンコーダに用いられる磁気センサは、少なくとも異なる２方向に沿って配置され、外部磁界によって磁化される複数の磁気抵抗素子を有する。前記磁気センサでは、前記外部磁界の磁界方向の変化を、前記複数の磁気抵抗素子を用いて検出する。　 For example, 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. *
ところで、前記磁気式エンコーダに前記磁気センサを用いた場合、前記磁気センサから出力される信号にノイズ等の誤差が含まれる可能性がある。そのため、例えば特許文献１に開示されるように、磁気式エンコーダを工場から出荷した後、所定のオフセット値を用いて、磁気センサの出力信号を補正する。　 By the way, when the magnetic sensor is used in the magnetic encoder, an error such as noise may be included in the signal output from the magnetic sensor. Therefore, as disclosed in Patent Document 1, for example, after the magnetic encoder is shipped from the factory, the output signal of the magnetic sensor is corrected using a predetermined offset value. *
なお、前記特許文献１に開示されている構成では、前記磁気式エンコーダの工場出荷後に、前記磁気センサから出力される出力信号における理想状態からのズレ量を用いて、前記オフセット値が補正される。これにより、磁気式エンコーダの工場出荷後に、前記オフセット値を調整した環境とは異なる環境下で前記磁気式エンコーダが使用された場合でも、前記センサの検出誤差を小さくすることができる。 In the configuration disclosed in Patent Document 1, after the factory shipment of the magnetic encoder, the offset value is corrected using an amount of deviation from an ideal state in the output signal output from the magnetic sensor. . Thereby, even if the magnetic encoder is used in an environment different from the environment in which the offset value is adjusted after the factory shipment of the magnetic encoder, the detection error of the sensor can be reduced.
特開２０１１－４７８２４号公報JP 2011-47824 A
ところで、前記磁気センサの出力信号の誤差には、磁気的な誤差が含まれる。この磁気的な誤差は、前記磁気センサの磁気抵抗素子が有する一軸磁気異方性の影響が大きい。また、この磁気抵抗素子が有する一軸磁気異方性は、磁気センサの出力信号の誤差にも大きく影響する。　 Incidentally, 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. *
すなわち、前記磁気抵抗素子が有する一軸磁気異方性によって、外部磁界によって磁化される前記磁気抵抗素子の磁化方向が影響を受ける。これにより、前記磁気抵抗素子の抵抗値が変化するため、前記磁気抵抗素子から、実際の出力信号とは異なる出力信号が出力される。そうすると、前記磁気センサによって、外部磁界の磁界方向の変化を精度良く検出できない。　 That is, the uniaxial magnetic anisotropy of the magnetoresistive element affects the magnetization direction of the magnetoresistive element that is magnetized by an external magnetic field. Thereby, 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. *
これに対し、上述の特許文献１に開示されるように、オフセット値を用いて磁気センサの出力信号を補正する方法が考えられる。しかしながら、前記特許文献１に開示されている構成では、前記オフセット値を磁気式エンコーダの工場出荷時に求めて設定する必要がある。しかも、前記オフセット値は、磁気センサ毎にそれぞれ異なるため、各磁気センサで前記オフセット値を求めて設定する必要がある。　 On the other hand, as disclosed in Patent Document 1 described above, a method of correcting the output signal of the magnetic sensor using an offset value is conceivable. However, in the configuration disclosed in Patent Document 1, it is necessary to obtain and set the offset value at the time of factory shipment of the magnetic encoder. Moreover, since the offset value is different for each magnetic sensor, it is necessary to obtain and set the offset value for each magnetic sensor. *
本発明の目的は、磁気センサ毎に補正値を用いることなく、前記一軸磁気異方性の影響を考慮して外部磁界の磁界方向を精度良く検出可能な磁気センサユニット及びそれを用いた磁界方向検出方法を提供することにある。 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.
本発明の一実施形態に係る磁気センサユニットは、少なくとも異なる２方向に沿って配置され、外部磁界によって磁化される複数の磁気抵抗素子と、前記複数の磁気抵抗素子に対して電圧を印加する電源部と、前記電源部によって前記複数の磁気抵抗素子に対して電圧を印加した場合に、各磁気抵抗素子の両端における電圧を検出する電圧検出部と、前記電圧検出部によって検出された電圧と、前記各磁気抵抗素子の異方性磁界の強さとを用いて、前記外部磁界の磁界方向を求める演算部と、を備える。前記演算部は、前記外部磁界の磁界方向及び前記各磁気抵抗素子が有する一軸磁気異方性によって決まる前記各磁気抵抗素子の磁化方向を、前記電圧検出部によって検出された電圧と前記各磁気抵抗素子の抵抗値とを用いて求める磁化方向算出部と、前記磁化方向と前記異方性磁界の強さとを用いて、前記外部磁界の前記磁界方向を算出する磁界方向算出部と、を有する。　 A magnetic sensor unit according to an embodiment of the present invention 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. *
本発明の一実施形態に係る磁気センサユニットを用いた磁界方向検出方法は、少なくとも異なる２方向に沿って配置され、外部磁界によって磁化される複数の磁気抵抗素子と、前記複数の磁気抵抗素子に対して電圧を印加する電源部と、を備えた磁気センサユニットを用いた磁界方向検出方法である。この磁界方向検出方法は、前記複数の磁気抵抗素子の両端におけるそれぞれの電圧を検出する電圧検出工程と、前記電圧検出工程で検出した前記電圧と各磁気抵抗素子の抵抗値とを用いて、前記複数の磁気抵抗素子の磁化方向を求める磁化方向算出工程と、前記磁化方向算出工程で算出した前記磁化方向と前記各磁気抵抗素子の異方性磁界の強さとを用いて、前記外部磁界の磁界方向を求める磁界方向算出工程と、を有する。 A magnetic field direction detection method using a magnetic sensor unit according to an embodiment of the present invention 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.
本発明の一実施形態に係る磁気センサユニット及びそれを用いた磁界方向検出方法によれば、磁気センサ毎に補正値を用いることなく、前記一軸磁気異方性の影響を考慮して外部磁界の磁界方向を精度良く検出することができる。 According to the magnetic sensor unit and the magnetic field direction detection method using the magnetic sensor unit according to the embodiment of the present invention, 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.
図１は、実施形態に係る磁気センサユニットの構成を模式的に示す図である。FIG. 1 is a diagram schematically illustrating a configuration of a magnetic sensor unit according to the embodiment. 図２は、外部磁界に対して磁気センサを配置した状態を模式的に示す図である。FIG. 2 is a diagram schematically showing a state in which the magnetic sensor is arranged with respect to the external magnetic field. 図３は、磁気抵抗素子によって構成される回路の回路図である。FIG. 3 is a circuit diagram of a circuit constituted by magnetoresistive elements. 図４は、磁気抵抗素子の一軸磁気異方性がＸ軸方向の場合において、外部磁界の磁界方向と磁気抵抗素子の磁化方向との関係を示す図である。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. 図５は、磁気抵抗素子の一軸磁気異方性がＹ軸方向の場合において、外部磁界の磁界方向と磁気抵抗素子の磁化方向との関係を示す図である。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. 図６は、外部磁界の強さと磁気抵抗素子の磁化との関係を示す図である。FIG. 6 is a diagram showing the relationship between the strength of the external magnetic field and the magnetization of the magnetoresistive element. 図７は、磁気センサユニットの動作を示すフローチャートである。FIG. 7 is a flowchart showing the operation of the magnetic sensor unit. 図８は、その他の実施形態に係る磁気センサユニットの図１相当図である。FIG. 8 is a view corresponding to FIG. 1 of a magnetic sensor unit according to another embodiment. 図９は、その他の実施形態に係る磁気センサユニットの磁気抵抗素子によって構成される回路の図３相当図である。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.
以下、図面を参照し、本発明の実施の形態を詳しく説明する。なお、図中の同一または相当部分については同一の符号を付してその説明は繰り返さない。また、各図中の構成部材の寸法は、実際の構成部材の寸法及び各構成部材の寸法比率等を忠実に表したものではない。　 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same or an equivalent part in a figure, and the description is not repeated. Moreover, the dimension of the structural member in each figure does not faithfully represent the actual dimension of the structural member, the dimensional ratio of each structural member, or the like. *
なお、以下の説明において、磁界の方向とは、Ｎ極からＳ極に向かって生じる磁界の向きを意味し、以下では、磁界の方向を単に磁界方向ともいう。また、磁化方向は、磁気抵抗素子が外部磁界によって磁化される方向を意味する。具体的には、前記磁化方向は、磁化された磁気抵抗素子において、Ｎ極からＳ極に向かう磁界の向きを意味する。　 In the following description, 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. *
（磁気センサユニット）

　図１は、本発明の実施形態に係る磁気センサユニット１の構成を模式的に示す図である。磁気センサユニット１は、外部磁界の変化を複数の磁気抵抗素子１１～１８によって検出可能な磁気センサ１０を有する。図２に示すように、磁気センサ１０は、例えば磁界（外部磁界）を生じる磁石２に対向して配置され、磁石２が生じる磁界の方向の変化を検出する。なお、図２において、破線で示す矢印は、磁石２が生じる磁界を示す。このように、外部磁界の磁界方向の変化を検出可能な磁気センサ１０は、例えば、モータの回転子の回転位置を検出するロータリーエンコーダなどに用いられる。　 (Magnetic sensor unit)

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. As shown in FIG. 2, 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. In FIG. 2, an arrow indicated by a broken line indicates a magnetic field generated by the magnet 2. Thus, 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.
図１に示すように、磁気センサユニット１は、磁気センサ１０と、電源部２０と、電圧検出部３０と、演算部４０とを備える。磁気センサ１０は、複数の磁気抵抗素子１１～１８を有する。すなわち、磁気センサユニット１は、複数の磁気抵抗素子１１～１８を有する。　 As shown in FIG. 1, 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. *
磁気抵抗素子１１～１８は、ＮｉＦｅなどの強磁性薄膜金属によって構成されている。よって、磁気抵抗素子１１～１８は、外部磁界によって磁化される。複数の磁気抵抗素子１１～１８は、例えば図示しない基板上に配置されている。以下の説明において、平面視とは、基板の表面（平面）を、該表面に対して法線方向から見た場合を意味する。なお、図１には、基板上における複数の磁気抵抗素子１１～１８の配置が、平面視で模式的に表されている。　 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. In the following description, the plan view means a case where the surface (plane) of the substrate is viewed from the normal direction with respect to the surface. In FIG. 1, the arrangement of the plurality of magnetoresistive elements 11 to 18 on the substrate is schematically shown in plan view. *
複数の磁気抵抗素子１１～１８は、平面視で同一方向に並ぶ一対の磁気抵抗素子を、４組含む。すなわち、本実施形態の磁気センサユニット１は、８つの磁気抵抗素子１１～１８を有する。８つの磁気抵抗素子１１～１８は、平面視で、同一方向に並ぶ一対の第１磁気抵抗素子１１及び第８磁気抵抗素子１８と、同一方向に並ぶ一対の第２磁気抵抗素子１２及び第７磁気抵抗素子１７と、同一方向に並ぶ一対の第３磁気抵抗素子１３及び第６磁気抵抗素子１６と、同一方向に並ぶ一対の第４磁気抵抗素子１４及び第５磁気抵抗素子１５とを含む。なお、図１における各磁気抵抗素子１１～１８における白抜き矢印は、各磁気抵抗素子１１～１８の一軸磁気異方性の方向を意味する。　 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. *
一対の第１磁気抵抗素子１１及び第８磁気抵抗素子１８と、一対の第２磁気抵抗素子１２及び第７磁気抵抗素子１７と、一対の第３磁気抵抗素子１３及び第６磁気抵抗素子１６と、一対の第４磁気抵抗素子１４及び第５磁気抵抗素子１５とは、それぞれ、平面視で異なる方向に沿って配置されている。すなわち、一対の第１磁気抵抗素子１１及び第８磁気抵抗素子１８が並ぶ方向と、一対の第２磁気抵抗素子１２及び第７磁気抵抗素子１７が並ぶ方向と、一対の第３磁気抵抗素子１３及び第６磁気抵抗素子１６が並ぶ方向と、一対の第４磁気抵抗素子１４及び第５磁気抵抗素子１５が並ぶ方向とは、平面視で異なる方向である。本実施形態では、平面視で、上述の各方向の間隔は、４５度である。　 A pair of first magnetoresistive element 11 and eighth magnetoresistive element 18, a pair of second magnetoresistive element 12 and seventh magnetoresistive element 17, a pair of third magnetoresistive element 13 and sixth magnetoresistive element 16, 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. In the present embodiment, the interval in each direction described above is 45 degrees in plan view. *
具体的には、一対の第１磁気抵抗素子１１及び第８磁気抵抗素子１８が並ぶ方向と、一対の第３磁気抵抗素子１３及び第６磁気抵抗素子１６が並ぶ方向とは、平面視で４５度異なる。一対の第３磁気抵抗素子１３及び第６磁気抵抗素子１６が並ぶ方向と、一対の第２磁気抵抗素子１２及び第７磁気抵抗素子１７が並ぶ方向とは、平面視で４５度異なる。一対の第２磁気抵抗素子１２及び第７磁気抵抗素子１７が並ぶ方向と、一対の第４磁気抵抗素子１４及び第５磁気抵抗素子１５が並ぶ方向とは、平面視で４５度異なる。一対の第４磁気抵抗素子１４及び第５磁気抵抗素子１５が並ぶ方向と、一対の第１磁気抵抗素子１１及び第８磁気抵抗素子１８が並ぶ方向とは、平面視で４５度異なる。　 Specifically, 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. *
これにより、一対の第１磁気抵抗素子１１及び第８磁気抵抗素子１８が並ぶ方向と、一対の第２磁気抵抗素子１２及び第７磁気抵抗素子１７が並ぶ方向とは、平面視で９０度異なる。また、一対の第３磁気抵抗素子１３及び第６磁気抵抗素子１６が並ぶ方向と、一対の第４磁気抵抗素子１４及び第５磁気抵抗素子１５が並ぶ方向とは、平面視で９０度異なる。すなわち、複数の磁気抵抗素子１１～１８は、平面視で直交する２方向に沿って配置された磁気抵抗素子を含む。　 Thus, 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. . In addition, 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. *
８つの磁気抵抗素子１１～１８のうち、平面視で異なる２方向に沿って配置された２つの磁気抵抗素子は、電気的に直列に接続されている。詳しくは、第１磁気抵抗素子１１から第８磁気抵抗素子１８のうち、平面視で、配置された方向が９０度異なる２つの磁気抵抗素子は、電気的に直列に接続されている。　 Of the eight 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. *
具体的には、第１磁気抵抗素子１１と第２磁気抵抗素子１２とが電気的に直列に接続されている。第３磁気抵抗素子１３と第４磁気抵抗素子１４とが電気的に直列に接続されている。第５磁気抵抗素子１５と第６磁気抵抗素子１６とが電気的に直列に接続されている。第７磁気抵抗素子１７と第８磁気抵抗素子１８とが電気的に直列に接続されている。　 Specifically, the 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. *
電気的に直列に接続された２つの磁気抵抗素子は、互いに電気的に並列に接続されている。すなわち、第１磁気抵抗素子１１及び第２磁気抵抗素子１２と、第３磁気抵抗素子１３及び第４磁気抵抗素子１４と、第５磁気抵抗素子１５及び第６磁気抵抗素子１６と、第７磁気抵抗素子１７及び第８磁気抵抗素子１８とは、電気的に並列に接続されている。これにより、８つの磁気抵抗素子１１～１８によって、図３に示す回路５０が構成される。　 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. Thus, the circuit 50 shown in FIG. 3 is constituted by the eight magnetoresistive elements 11 to 18. *
なお、図１及び図３におけるＲ１からＲ８は、それぞれ、第１磁気抵抗素子１１から第８磁気抵抗素子１８の抵抗値である。具体的には、Ｒ１は第１磁気抵抗素子１１の抵抗値であり、Ｒ２は第２磁気抵抗素子１２の抵抗値であり、Ｒ３は第３磁気抵抗素子１３の抵抗値であり、Ｒ４は第４磁気抵抗素子１４の抵抗値である。また、Ｒ５は第５磁気抵抗素子１５の抵抗値であり、Ｒ６は第６磁気抵抗素子１６の抵抗値であり、Ｒ７は第７磁気抵抗素子１７の抵抗値である。Ｒ８は第８磁気抵抗素子１８の抵抗値である。　 Note that 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. Specifically, R 1 is the resistance value of the first magnetoresistive element 11, R 2 is the resistance value of the second magnetoresistive element 12, and 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 15, R 6 is the resistance value of the sixth magnetoresistive element 16, and R 7 is the resistance value of the seventh magnetoresistive element 17. R 8 is the resistance value of the eighth magnetoresistive element 18.
図１に示すように、例えば、第１磁気抵抗素子１１及び第８磁気抵抗素子１８をＸ軸に沿って配置した場合、平面視でＸ軸に対する外部磁界の角度をθとすると、Ｒ１からＲ８は下式によって表される。なお、第１磁気抵抗素子１１及び第８磁気抵抗素子１８には、Ｘ軸方向に電流を流し、第２磁気抵抗素子１２及び第７磁気抵抗素子１７には、平面視でＸ軸に対して９０度の方向、すなわちＹ軸方向に電流を流し、第３磁気抵抗素子１３及び第６磁気抵抗素子１６には、平面視でＸ軸に対して４５度の方向に電流を流し、第４磁気抵抗素子１４及び第５磁気抵抗素子１５には、平面視でＸ軸に対して１３５度の方向に電流を流す。

　Ｒ１＝Ｒ０－ΔＲｓｉｎ２（θ）

　Ｒ２＝Ｒ０－ΔＲｓｉｎ２（π／２－θ）

　Ｒ３＝Ｒ０－ΔＲｓｉｎ２（π／４－θ）

　Ｒ４＝Ｒ０－ΔＲｓｉｎ２（π／４＋θ）

　Ｒ５＝Ｒ０－ΔＲｓｉｎ２（π／４＋θ）

　Ｒ６＝Ｒ０－ΔＲｓｉｎ２（π／４－θ）

　Ｒ７＝Ｒ０－ΔＲｓｉｎ２（π／２－θ）

　Ｒ８＝Ｒ０－ΔＲｓｉｎ２（θ）

　ここで、Ｒ０は無磁界中の磁気抵抗素子１１～１８の抵抗値であり、ΔＲは外部磁界が変化した場合における磁気抵抗素子１１～１８の抵抗値の変化量である。　 As shown in FIG. 1, for example, when the first magnetoresistive element 11 and the eighth magnetoresistive element 18 are arranged along the X axis, when the angle of the external magnetic field with respect to the X axis is θ in plan view, 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 −ΔR sin 2 (θ)

R 2 = R 0 −ΔR sin 2 (π / 2−θ)

R 3 = R 0 -ΔRsin 2 (π / 4-θ)

R 4 = R 0 −ΔR sin 2 (π / 4 + θ)

R 5 = R 0 −ΔR sin 2 (π / 4 + θ)

R 6 = R 0 −ΔR sin 2 (π / 4−θ)

R 7 = R 0 −ΔRsin 2 (π / 2−θ)

R 8 = R 0 −ΔR sin 2 (θ)

Here, R 0 is the resistance value of the magnetoresistive elements 11 to 18 in the absence of a magnetic field, and ΔR is the change amount of the resistance value of the magnetoresistive elements 11 to 18 when the external magnetic field changes.
電源部２０は、図３に示すように、回路５０に対し、所定の電圧Ｖｐを印加する。すなわち、電源部２０は、直列に接続された２つの磁気抵抗素子に対し、それぞれ、所定の電圧Ｖｐを印加する。すなわち、電源部２０は、直列に接続された第１磁気抵抗素子１１及び第２磁気抵抗素子１２に対して所定の電圧Ｖｐを印加する。電源部２０は、直列に接続された第３磁気抵抗素子１３及び第４磁気抵抗素子１４に対して所定の電圧Ｖｐを印加する。電源部２０は、直列に接続された第５磁気抵抗素子１５及び第６磁気抵抗素子１６に対して所定の電圧Ｖｐを印加する。電源部２０は、直列に接続された第７磁気抵抗素子１７及び第８磁気抵抗素子１８に対して所定の電圧Ｖｐを印加する。　 As shown in FIG. 3, 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. *
電圧検出部３０は、直列に接続された２つの磁気抵抗素子の中間電位を検出する。すなわち、電圧検出部３０は、第１磁気抵抗素子１１と第２磁気抵抗素子１２との中間電位ＶＢ－、第３磁気抵抗素子１３と第４磁気抵抗素子１４との中間電位ＶＡ－、第５磁気抵抗素子１５と第６磁気抵抗素子１６との中間電位ＶＡ＋、第７磁気抵抗素子１７と第８磁気抵抗素子１８との中間電位ＶＢ＋をそれぞれ検出する。電圧検出部３０は、これらの中間電位の差（ＶＢ＋－ＶＢ－、ＶＡ＋－ＶＡ－）を検出する。これにより、磁気抵抗素子１１～１８の両端の電圧を容易に且つ精度良く検出することができる。　 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.
演算部４０は、電圧検出部３０で検出された磁気抵抗素子１１～１８の両端の電圧と、磁気抵抗素子１１～１８の抵抗値と、磁気抵抗素子１１～１８の異方性磁界の強さとを用いて、外部磁界の磁界方向を求める。具体的には、演算部４０は、磁化方向算出部４１と、磁界方向算出部４２とを備える。　 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. Specifically, the calculation unit 40 includes a magnetization direction calculation unit 41 and a magnetic field direction calculation unit 42. *
磁化方向算出部４１は、前記外部磁界の磁界方向と磁気抵抗素子１１～１８が有する一軸磁気異方性とによって決まる磁気抵抗素子１１～１８の磁化方向を、算出する。磁化方向算出部４１は、磁気抵抗素子１１～１８の磁化方向を、電圧検出部３０によって検出された磁気抵抗素子１１～１８の両端の電圧と、磁気抵抗素子１１～１８の抵抗値とを用いて求める。　 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. Ask. *
既述のように、磁気抵抗素子１１～１８は、外部磁界によって磁化される。しかしながら、磁気抵抗素子１１～１８が一軸磁気異方性を有するため、磁気抵抗素子１１～１８の磁化方向は、前記一軸磁気異方性の影響を受ける。　 As described above, 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. *
外部磁界の磁界方向、磁気抵抗素子１１～１８の磁化方向、磁気抵抗素子１１～１８の一軸磁気異方性の関係を図４及び図５に示す。図４は、磁気抵抗素子１１～１８の一軸磁気異方性ＫがＸ軸方向の場合に、外部磁界の磁界方向と、磁気抵抗素子１１～１８の磁化Ｍｓの方向との関係を模式的に示す。図５は、磁気抵抗素子１１～１８の一軸磁気異方性ＫがＹ軸方向の場合に、外部磁界の磁界方向と、磁気抵抗素子１１～１８の磁化Ｍｓの方向との関係を模式的に示す。　 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. 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. Show. 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. *
図４及び図５に示すように、磁気抵抗素子１１～１８の一軸磁気異方性Ｋによって、外部磁界によって磁化される磁気抵抗素子１１～１８の磁化Ｍｓの方向（磁化方向）は影響を受ける。　 As shown in FIGS. 4 and 5, 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. . *
図４に示す場合において、第１磁気抵抗素子１１及び第８磁気抵抗素子１８の抵抗値Ｒ１，Ｒ８は、以下の（式１）、（式２）によって表される。θ１は、Ｘ軸と第１磁気抵抗素子１１の磁化方向とがなす角度である。

（式１）Ｒ１＝Ｒ０－ΔＲｓｉｎ２（θ１）

（式２）Ｒ８＝Ｒ０－ΔＲｓｉｎ２（θ１）
In the case shown in FIG. 4, 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). θ 1 is an angle formed by the X axis and the magnetization direction of the first magnetoresistive element 11.

(Formula 1) R 1 = R 0 −ΔR sin 2 (θ 1 )

(Formula 2) R 8 = R 0 −ΔR sin 2 (θ 1 )
また、図４に示す場合において、第４磁気抵抗素子１４及び第５磁気抵抗素子１５の抵抗値Ｒ４，Ｒ５は、以下の（式３）、（式４）によって表される。

（式３）Ｒ４＝Ｒ０－ΔＲｓｉｎ２（π／４＋θ１）

（式４）Ｒ５＝Ｒ０－ΔＲｓｉｎ２（π／４＋θ１）
In the case shown in FIG. 4, 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).

(Formula 3) R 4 = R 0 −ΔR sin 2 (π / 4 + θ 1 )

(Formula 4) R 5 = R 0 −ΔR sin 2 (π / 4 + θ 1 )
図５に示す場合において、第２磁気抵抗素子１２及び第７磁気抵抗素子１７の抵抗値Ｒ２，Ｒ７は、以下の（式５）、（式６）式によって表される。θ２は、Ｘ軸と第１磁気抵抗素子１１の磁化Ｍｓの方向とがなす角度である。

（式５）Ｒ２＝Ｒ０－ΔＲｓｉｎ２（π／２－θ２）

（式６）Ｒ７＝Ｒ０－ΔＲｓｉｎ２（π／２－θ２）
In the case shown in FIG. 5, 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). θ 2 is an angle formed by the X axis and the direction of the magnetization Ms of the first magnetoresistive element 11.

(Formula 5) R 2 = R 0 −ΔR sin 2 (π / 2−θ 2 )

(Formula 6) R 7 = R 0 −ΔR sin 2 (π / 2−θ 2 )
また、図５に示す場合において、第３磁気抵抗素子１３及び第６磁気抵抗素子１６の抵抗Ｒ３，Ｒ６は、以下の（式７）、（式８）によって表される。

（式７）Ｒ３＝Ｒ０－ΔＲｓｉｎ２（π／４－θ２）

（式８）Ｒ６＝Ｒ０－ΔＲｓｉｎ２（π／４－θ２）
In the case shown in FIG. 5, 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).

(Formula 7) R 3 = R 0 −ΔR sin 2 (π / 4−θ 2 )

(Formula 8) R 6 = R 0 −ΔR sin 2 (π / 4−θ 2 )
上述の（式１）から（式８）の各式における抵抗値Ｒ１からＲ８は、外部磁界による磁気抵抗素子１１～１８の磁化が磁気抵抗素子１１～１８の一軸磁気異方性によって影響を受けている場合の抵抗値である。　 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.
磁化方向算出部４１は、電圧検出部３０によって検出された中間電位ＶＢ－，ＶＢ＋，ＶＡ－，ＶＡ＋（または中間電圧ＶＢ，ＶＡ）を、以下の（式９）及び（式１０）にそれぞれ代入することにより、θ１，θ２を求める。なお、以下の（式９）及び（式１０）において、Ｒ１からＲ８に上述の（式１）から（式８）の各式を代入することにより、磁化方向θ１，θ２の関係式が得られる。

（式９）

Figure JPOXMLDOC01-appb-I000001
 （式１０）

Figure JPOXMLDOC01-appb-I000002
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), θ 1 and θ 2 are obtained. In the following (Expression 9) and (Expression 10), the relationship between the magnetization directions θ 1 and θ 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)

Figure JPOXMLDOC01-appb-I000001
(Formula 10)

Figure JPOXMLDOC01-appb-I000002
磁界方向算出部４２は、磁化方向算出部４１によって算出されたθ１，θ２と、磁気抵抗素子１１～１８の異方性磁界の強さとを用いて、図４及び図５におけるφ、すなわち外部磁界の磁界方向を求める。なお、φは、磁気抵抗素子１１～１８に流れる電流の方向（電流方向）に対する外部磁界の磁界方向の角度である。　 The magnetic field direction calculation unit 42 uses the θ 1 and θ 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, φ in FIG. 4 and FIG. Obtain the magnetic field direction of the external magnetic field. Note that φ 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).
前記異方性磁界の強さは、磁気抵抗素子１１～１８において、磁化困難方向に外部磁界を与えて、磁化が飽和したときの磁場の強さを意味する。磁気抵抗素子１１～１８を磁化容易方向及び磁化困難方向に磁化させた場合、図６に示すような外部磁界の強さＨと磁化Ｍとの関係が得られる。前記異方性磁界の強さは、磁気抵抗素子１１～１８を磁化困難方向に磁化させた際に、磁化が飽和磁化Ｍｓに達したときの磁場の強さＨａである。なお、前記異方性磁界の強さは、例えば、実測によって求められる。　 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. When the magnetoresistive elements 11 to 18 are magnetized in the easy magnetization direction and the hard magnetization direction, the relationship between the external magnetic field strength H and the magnetization M as shown in FIG. 6 is obtained. 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. *
ところで、外部磁界によって磁化される磁気抵抗素子１１～１８に生じる単位体積当たりのエネルギーＦは、磁気異方性エネルギー及び外部磁界のエネルギーを考慮すると、下式によって求められる。

（式１１）Ｆ＝Ｋｓｉｎ２（θ）－ＭｓＨｃｏｓ（φ－θ）
By the way, 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.

(Formula 11) F = Ksin 2 (θ) −MsH cos (φ−θ)
上式の両辺をＫで割ると、

（式１２）ｆ＝Ｆ／Ｋ＝ｓｉｎ２（θ）－２ｈｃｏｓ（φ－θ）

　ここで、

　　ｈ（換算磁界）＝Ｈ／Ｈａ

　　Ｈａ＝２Ｋ／Ｍｓより、ＭｓＨ／Ｋ＝２Ｈ（Ｍｓ／（２Ｋ））＝２Ｈ／Ｈａ＝２ｈ

　　φ：外部磁界の磁界方向（ｒａｄ）

　　θ：各磁気抵抗素子の磁化方向（ｒａｄ）

　　Ｈ：外部磁界の強さ（Ａ／ｍ）

　　Ｈａ：各磁気抵抗素子の異方性磁界の強さ（Ａ／ｍ）
Dividing both sides of the above equation by K,

(Formula 12) f = F / K = sin 2 (θ) −2hcos (φ−θ)

here,

h (converted magnetic field) = H / Ha

From Ha = 2K / Ms, MsH / K = 2H (Ms / (2K)) = 2H / Ha = 2h

φ: Magnetic field direction of external magnetic field (rad)

θ: Magnetization direction (rad) of each magnetoresistive element

H: Strength of external magnetic field (A / m)

Ha: Strength of anisotropic magnetic field of each magnetoresistive element (A / m)
上述の（式１２）にｆ＝０を代入して、φについて解くことにより、下式が得られる。

（式１３）φ＝ａｒｃｃｏｓ（ｓｉｎ２θ／（２ｈ））＋θ
By substituting f = 0 into the above (formula 12) and solving for φ, the following formula is obtained.

(Expression 13) φ = arccos (sin 2 θ / (2h)) + θ
よって、換算磁界ｈ及び磁化方向θ１，θ２を用いて、外部磁界の磁界方向φを求めることができる。なお、換算磁界ｈは、外部磁界の強さＨと異方性磁界の強さＨａとによって決まる。そのため、異方性磁界の強さＨａの値と磁化方向θ１，θ２とが決まれば、外部磁界の磁界方向φを求めることができる。　 Therefore, the magnetic field direction φ of the external magnetic field can be obtained using the converted magnetic field h and the magnetization directions θ 1 and θ 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 θ 1 and θ 2 are determined, the magnetic field direction φ of the external magnetic field can be obtained.
なお、（式１３）から分かるように、換算磁界ｈが小さいほど、すなわち、外部磁界の強さＨが異方性磁界の強さＨａに近いほど、外部磁界の磁界方向φの算出結果に対する異方性磁界の影響が大きい。　 As can be seen from (Equation 13), the smaller the converted magnetic field h, that is, the closer the strength H of the external magnetic field is to the strength Ha of the anisotropic magnetic field, the more different the calculation result of the magnetic field direction φ of the external magnetic field. The influence of the isotropic magnetic field is large. *
磁界方向算出部４２は、上述の（式１３）に、異方性磁界の強さＨａの値と磁化方向θ１，θ２とを代入することにより、外部磁界の磁界方向φを算出する。なお、磁界方向算出部４２は、磁化方向θ１，θ２のいずれか一方の値を用いて、外部磁界の磁界方向φを算出してもよいし、磁化方向θ１，θ２の両方の値を用いて外部磁界の磁界方向φをそれぞれ算出した後、それらの平均値を外部磁界の磁界方向としてもよい。　 The magnetic field direction calculation unit 42 calculates the magnetic field direction φ of the external magnetic field by substituting the value Ha of the anisotropic magnetic field and the magnetization directions θ 1 and θ 2 into the above (Equation 13). Incidentally, the magnetic field direction calculation unit 42, the magnetization direction theta 1, with one value of theta 2, may calculate the magnetic field direction φ of the external magnetic field, the magnetization direction theta 1, both theta 2 After calculating the magnetic field direction φ of the external magnetic field using the values, the average value thereof may be used as the magnetic field direction of the external magnetic field.
既述のように、磁気センサユニット１の複数の磁気抵抗素子１１～１８は、それぞれ、一軸磁気異方性を有する。そのため、複数の磁気抵抗素子１１～１８は、外部磁界によって磁化される際に、外部磁界の磁界方向とは異なる方向に磁化される。よって、磁気センサユニット１の磁気抵抗素子１１～１８の磁化方向を検出しても、外部磁界の磁界方向を精度良く求めることはできない。　 As described above, 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. *
これに対し、本実施形態の構成では、外部磁界によって磁化された各磁気抵抗素子１１～１８の磁化方向θ１，θ２と、各磁気抵抗素子１１～１８の異方性磁界の強さＨａとを用いて、外部磁界の磁界方向φを求める。これにより、磁気抵抗素子１１～１８の一軸磁気異方性を考慮して、外部磁界の磁界方向φを求めることができる。　 On the other hand, in the configuration of this embodiment, the magnetization directions θ 1 and θ 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. Are used to determine the magnetic field direction φ of the external magnetic field. Accordingly, the magnetic field direction φ of the external magnetic field can be obtained in consideration of the uniaxial magnetic anisotropy of the magnetoresistive elements 11 to 18.
しかも、上述の構成では、磁気抵抗素子１１～１８の一軸磁気異方性を考慮した外部磁界の磁界方向φを演算によって求めることができる。よって、従来のように、磁気抵抗素子１１～１８の一軸磁気異方性を考慮した補正値を用意する必要がない。　 In addition, in the above-described configuration, the magnetic field direction φ 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. *
したがって、上述の構成により、複数の磁気抵抗素子１１～１８を用いて、外部磁界の磁界方向φを容易に且つ精度良く検出することができる。　 Therefore, with the above-described configuration, the magnetic field direction φ of the external magnetic field can be easily and accurately detected using the plurality of magnetoresistive elements 11 to 18. *
また、本実施形態では、複数の磁気抵抗素子１１～１８は、平面視で直交する２方向に沿って配置された磁気抵抗素子（例えば第１磁気抵抗素子１１及び第２磁気抵抗素子１２など）を含む。これにより、直交する２方向に沿って配置された２つの磁気抵抗素子を用いて、外部磁界の磁界方向φを精度良く検出することができる。すなわち、前記２つの磁気抵抗素子を用いることにより、外部磁界の磁界方向φと前記２つの磁気抵抗素子の磁化方向θ１，θ２との関係を、三角関数を用いた式によって規定できる。よって、この式を用いることにより、磁気抵抗素子１１～１８の一軸磁気異方性を考慮した外部磁界の磁界方向φを演算によって精度良く求めることができる。　 In the present embodiment, 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. Thus, the magnetic field direction φ 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 φ of the external magnetic field and the magnetization directions θ 1 and θ 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 φ 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.
（磁気センサユニットの動作）

　次に、上述の構成を有する磁気センサユニット１の動作を、図７を用いて説明する。図７は、磁気センサユニット１の動作を示すフローチャートである。　 (Operation of magnetic sensor unit)

Next, the operation of the magnetic sensor unit 1 having the above-described configuration will be described with reference to FIG. FIG. 7 is a flowchart showing the operation of the magnetic sensor unit 1.
図７に示すように、まず、ステップＳ１において、電圧検出部３０によって、磁気抵抗素子１１～１８の両端の電圧を検出する。すなわち、電圧検出部３０によって、第１磁気抵抗素子１１と第２磁気抵抗素子１２との中間電位ＶＢ－、第３磁気抵抗素子１３と第４磁気抵抗素子１４との中間電位ＶＡ－、第５磁気抵抗素子１５と第６磁気抵抗素子１６との中間電位ＶＡ＋、第７磁気抵抗素子１７と第８磁気抵抗素子１８との中間電位ＶＢ＋を、それぞれ検出する。具体的には、電圧検出部３０は、これらの中間電位の差（ＶＢ＋－ＶＢ－、ＶＡ＋－ＶＡ－）を検出することにより、磁気抵抗素子１１～１８の両端の電圧を検出することができる。　 As shown in FIG. 7, first, in 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.
次に、ステップＳ２において、演算部４０の磁化方向算出部３１が、ステップＳ１で検出された磁気抵抗素子１１～１８の両端に作用する電圧を用いて、下式からθ１，θ２を算出する。なお、下式は、既述の（式９）及び（式１０）である。

（式９）

Figure JPOXMLDOC01-appb-I000003
 （式１０）

Figure JPOXMLDOC01-appb-I000004
Next, in step S2, the magnetization direction calculation unit 31 of the calculation unit 40 calculates θ 1 and θ 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)

Figure JPOXMLDOC01-appb-I000003
(Formula 10)

Figure JPOXMLDOC01-appb-I000004
続くステップＳ３では、ステップＳ２で求めたθ１，θ２と、予め求められている異方性磁界の強さＨａとを用いて、下式からφを求める。なお、下式は、既述の（式１３）である。

（式１３）φ＝ａｒｃｃｏｓ（ｓｉｎ２θ／（２ｈ））＋θ
In subsequent step S3, φ is obtained from the following equation using θ 1 and θ 2 obtained in step S2 and the strength Ha of the anisotropic magnetic field obtained in advance. The following expression is the above-described (Expression 13).

(Expression 13) φ = arccos (sin 2 θ / (2h)) + θ
これにより、磁気抵抗素子１１～１８に流れる電流の電流方向に対する外部磁界の磁界方向φを求めることができる。よって、電圧検出部３０によって検出される磁気抵抗素子１１～１８の両端における電圧と、磁気抵抗素子１１～１８の異方性磁界の強さＨａとを用いて、外部磁界の磁界方向φを算出できる。　 Thereby, the magnetic field direction φ 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 φ 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. *
ここで、ステップＳ１が、電圧検出工程に対応する。ステップＳ２が磁化方向算出工程に対応する。ステップＳ３が磁界方向算出工程に対応する。　 Here, 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. *
（その他の実施形態）

　以上、本発明の実施の形態を説明したが、上述した実施の形態は本発明を実施するための例示に過ぎない。よって、上述した実施の形態に限定されることなく、その趣旨を逸脱しない範囲内で上述した実施の形態を適宜変形して実施することが可能である。　 (Other embodiments)

While the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified and implemented without departing from the spirit of the invention.
前記実施形態では、磁気センサユニット１は、８つの磁気抵抗素子１１～１８を有する。しかしながら、磁気センサユニットは、平面視で異なる２方向に沿って配置された磁気抵抗素子を有していればよい。すなわち、磁気センサユニットにおいて、平面視で同一方向に並ぶ一対の磁気抵抗素子が、９０度の間隔で２組、配置されていてもよい。よって、磁気センサユニットは、少なくとも４つの磁気抵抗素子を有していればよい。　 In the embodiment, the magnetic sensor unit 1 has eight magnetoresistive elements 11 to 18. However, the magnetic sensor unit should just have the magnetoresistive element arrange | positioned along two different directions by planar view. That is, in the magnetic sensor unit, two pairs of magnetoresistive elements arranged in the same direction in plan view may be arranged at an interval of 90 degrees. Therefore, the magnetic sensor unit only needs to have at least four magnetoresistive elements. *
図８に、４つの磁気抵抗素子１１，１２，１７，１８を備えた磁気センサユニット１０１の構成を模式的に示す。磁気センサユニット１０１は、外部磁界の変化を複数の磁気抵抗素子１１，１２，１７，１８によって検出可能な磁気センサ１１０を有する。　 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. *
複数の磁気抵抗素子１１，１２，１７，１８は、平面視で同一方向に並ぶ一対の磁気抵抗素子を、２組含む。すなわち、４つの磁気抵抗素子１１，１２，１７，１８は、平面視で、同一方向に並ぶ一対の第１磁気抵抗素子１１及び第８磁気抵抗素子１８と、同一方向に並ぶ一対の第２磁気抵抗素子１２及び第７磁気抵抗素子１７とを含む。一対の第１磁気抵抗素子１１及び第８磁気抵抗素子１８と、一対の第２磁気抵抗素子１２及び第７磁気抵抗素子１７とは、それぞれ、平面視で異なる方向に沿って配置されている。磁気センサユニット１０１では、平面視で、上述の各方向の間隔は、９０度である。　 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. *
第１磁気抵抗素子１１と第２磁気抵抗素子１２とが電気的に直列に接続されている。第７磁気抵抗素子１７と第８磁気抵抗素子１８とが電気的に直列に接続されている。第１磁気抵抗素子１１及び第２磁気抵抗素子１２と、第７磁気抵抗素子１７及び第８磁気抵抗素子１８とは、電気的に並列に接続されている。　 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. *
これにより、４つの磁気抵抗素子１１，１２，１７，１８によって、図９に示す回路１５０が構成される。なお、図８及び図９におけるＲ１，Ｒ２，Ｒ７，Ｒ８は、それぞれ、第１磁気抵抗素子１１、第２磁気抵抗素子１２、第７磁気抵抗素子１７及び第８磁気抵抗素子１８の抵抗値である。また、前記実施形態の図４及び図５に示す場合において、Ｒ１，Ｒ２，Ｒ７，Ｒ８は、前記実施形態の（式１）、（式５）、（式６）、（式２）で表される。

　電圧検出部３０は、第１磁気抵抗素子１１と第２磁気抵抗素子１２との中間電位ＶＢ、第７磁気抵抗素子１７と第８磁気抵抗素子１８との中間電位ＶＡをそれぞれ検出する。　 As a result, the circuit 150 shown in FIG. 9 is configured by the four magnetoresistive elements 11, 12, 17, and 18. Note that 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. In the case shown in FIGS. 4 and 5 of the embodiment, 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.
なお、その他の構成は、前記実施形態における磁気センサユニット１と同様なので、詳しい説明を省略する。　 In addition, since the other structure is the same as that of the magnetic sensor unit 1 in the said embodiment, detailed description is abbreviate | omitted. *
磁化方向算出部４１は、電圧検出部３０によって検出された中間電位ＶＢ，ＶＡを、以下の（式１４）及び（式１５）にそれぞれ代入することにより、θ１，θ２を求める。なお、以下の（式１４）及び（式１５）において、Ｒ１，Ｒ２，Ｒ７，Ｒ８に上述の（式１）、（式５）、（式６）、（式２）の各式を代入することにより、磁化方向θ１，θ２の関係式が得られる。

（式１４）

Figure JPOXMLDOC01-appb-I000005
 （式１５）

Figure JPOXMLDOC01-appb-I000006
The magnetization direction calculation unit 41 obtains θ 1 and θ 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. In the following (Formula 14) and (Formula 15), R 1 , R 2 , R 7 , R 8 are represented by the above (Formula 1), (Formula 5), (Formula 6), and (Formula 2), respectively. By substituting the equation, the relational expression of the magnetization directions θ 1 and θ 2 can be obtained.

(Formula 14)

Figure JPOXMLDOC01-appb-I000005
(Formula 15)

Figure JPOXMLDOC01-appb-I000006
磁界方向算出部４２は、前記実施形態の（式１３）に、異方性磁界の強さＨａの値と磁化方向算出部４１で求めた磁化方向θ１，θ２とを代入することにより、外部磁界の磁界方向φを算出する。　 The magnetic field direction calculation unit 42 substitutes the value of the anisotropic magnetic field intensity Ha and the magnetization directions θ 1 and θ 2 obtained by the magnetization direction calculation unit 41 into (Equation 13) of the above embodiment. The magnetic field direction φ of the external magnetic field is calculated.
これにより、各磁気抵抗素子１１，１２，１７，１８の一軸磁気異方性を考慮して、外部磁界の磁界方向φを求めることができる。　 Thereby, the magnetic field direction φ 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. *
前記実施形態では、磁気センサユニット１は、平面視で同一方向に並ぶ一対の磁気抵抗素子を、４組有する。しかしながら、磁気センサユニットは、第１磁気抵抗素子１１、第２磁気抵抗素子１２、第３磁気抵抗素子１３及び第４磁気抵抗素子１４のみを有していてもよい。この場合には、電圧検出部２０によって、磁気抵抗素子１１～１４の両端における電圧を検出することにより、前記実施形態と同様の方法によって、外部磁界の磁界方向φを算出することができる。　 In the embodiment, the magnetic sensor unit 1 has four pairs of magnetoresistive elements arranged in the same direction in plan view. However, 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. In this case, by detecting the voltage at both ends of the magnetoresistive elements 11 to 14 by the voltage detection unit 20, the magnetic field direction φ of the external magnetic field can be calculated by the same method as in the above embodiment. *
前記実施形態では、磁気センサユニット１は、磁気抵抗素子１１～１８の両端の電圧を検出するために、電気的に直列に接続された一対の磁気抵抗素子の中間電位を検出する。しかしながら、磁気センサユニットは、磁気抵抗素子１１～１８の両端の電圧を検出可能な構成であれば、例えば他の構成によって磁気抵抗素子１１～１８の両端の電圧を検出してもよい。　 In the 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. However, 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. *
前記実施形態では、磁気抵抗素子１１～１８の磁化方向θ１，θ２及び外部磁界の磁界方向φを、図１に示すＸ軸を基準として規定しているが、この限りではなく、例えばＹ軸など、Ｘ軸以外を基準として、磁化方向θ１，θ２及び磁界方向φを規定してもよい。 In the above-described embodiment, the magnetization directions θ 1 and θ 2 of the magnetoresistive elements 11 to 18 and the magnetic field direction φ of the external magnetic field are defined with reference to the X axis shown in FIG. The magnetization directions θ 1 and θ 2 and the magnetic field direction φ may be defined with reference to axes other than the X axis.
本発明は、複数の磁気抵抗素子を有する磁気センサユニットに利用可能である。 The present invention is applicable to a magnetic sensor unit having a plurality of magnetoresistive elements.

１、１０１　磁気センサユニット

１０、１１０　磁気センサ

１１　第１磁気抵抗素子

１２　第２磁気抵抗素子

１３　第３磁気抵抗素子

１４　第４磁気抵抗素子

１５　第５磁気抵抗素子

１６　第６磁気抵抗素子

１７　第７磁気抵抗素子

１８　第８磁気抵抗素子

２０　電源部

３０　電圧検出部

４０　演算部

５０、１５０　回路

θ１、θ２　磁気抵抗素子の磁化方向

φ　外部磁界の磁界方向

Ｈ　外部磁界の強さ

Ｍｓ　磁気抵抗素子の磁化

Ｒ１～Ｒ８　磁気抵抗素子の抵抗値
1, 101 Magnetic sensor unit

10, 110 Magnetic sensor

11 First magnetoresistive element

12 Second magnetoresistive element

13 Third magnetoresistive element

14 Fourth magnetoresistive element

15 Fifth magnetoresistive element

16 6th magnetoresistive element

17 7th magnetoresistive element

18 Eighth magnetoresistive element

20 Power supply

30 Voltage detector

40 Calculation unit

50, 150 circuits

Magnetization direction of θ 1 , θ 2 magnetoresistive element

φ Magnetic field direction of external magnetic field

H Strength of external magnetic field

Ms Magnetization of magnetoresistive element

R 1 to R 8 magnetoresistive element resistance values

Claims (6)

  1. 磁気センサユニットであって、少なくとも異なる２方向に沿って配置され、外部磁界によって磁化される複数の磁気抵抗素子と、前記複数の磁気抵抗素子に対して電圧を印加する電源部と、前記電源部によって前記複数の磁気抵抗素子に対して電圧を印加した場合に、各磁気抵抗素子の両端における電圧を検出する電圧検出部と、前記電圧検出部によって検出された電圧と、前記各磁気抵抗素子の異方性磁界の強さとを用いて、前記外部磁界の磁界方向を求める演算部と、を備え、前記演算部は、前記外部磁界の磁界方向及び前記各磁気抵抗素子が有する一軸磁気異方性によって決まる前記各磁気抵抗素子の磁化方向を、前記電圧検出部によって検出された電圧と前記各磁気抵抗素子の抵抗値とを用いて求める磁化方向算出部と、前記磁化方向と前記異方性磁界の強さとを用いて、前記外部磁界の前記磁界方向を算出する磁界方向算出部と、を有する、磁気センサユニット。 A magnetic sensor unit, which is arranged along at least two different directions and is magnetized by an external magnetic field, a power supply unit for applying a voltage to the plurality of magnetoresistive elements, and the power supply unit When a voltage is applied to the plurality of magnetoresistive elements, a voltage detecting unit that detects voltages at both ends of each magnetoresistive element, a voltage detected by the voltage detecting unit, and a A calculation unit that determines the magnetic field direction of the external magnetic field using the strength of the anisotropic magnetic field, and the calculation unit includes the magnetic field direction of the external magnetic field and the uniaxial magnetic anisotropy of each magnetoresistive element A magnetization direction calculating unit for obtaining a magnetization direction of each of the magnetoresistive elements determined by a voltage detected by the voltage detecting unit and a resistance value of each of the magnetoresistive elements, and the magnetization method Wherein by using the strength of the anisotropy field, having a magnetic field direction calculation unit for calculating the magnetic field direction of the external magnetic field, the magnetic sensor unit with.
  2. 請求項１に記載の磁気センサユニットにおいて、前記複数の磁気抵抗素子のうち異なる２方向に沿って配置された２つの磁気抵抗素子は、電気的に直列に接続され、前記電圧検出部は、前記直列に接続された２つの磁気抵抗素子の中間電位を検出する、磁気センサユニット。 2. The magnetic sensor unit according to claim 1, wherein two magnetoresistive elements arranged along two different directions among the plurality of magnetoresistive elements are electrically connected in series, and the voltage detection unit A magnetic sensor unit that detects an intermediate potential between two magnetoresistive elements connected in series.
  3. 請求項１または２に記載の磁気センサユニットにおいて、前記異なる２方向は、直交する２方向である、磁気センサユニット。 3. The magnetic sensor unit according to claim 1, wherein the two different directions are two directions orthogonal to each other.
  4. 請求項１から３のいずれか一つに記載の磁気センサユニットにおいて、前記複数の磁気抵抗素子は、少なくとも異なる４方向に沿って配置されている、磁気センサユニット。 4. The magnetic sensor unit according to claim 1, wherein the plurality of magnetoresistive elements are arranged along at least four different directions. 5.
  5. 少なくとも異なる２方向に沿って配置され、外部磁界によって磁化される複数の磁気抵抗素子と、前記複数の磁気抵抗素子に対して電圧を印加する電源部と、を備えた磁気センサユニットを用いた磁界方向検出方法であって、前記複数の磁気抵抗素子の両端におけるそれぞれの電圧を検出する電圧検出工程と、前記電圧検出工程で検出した前記電圧と各磁気抵抗素子の抵抗値とを用いて、前記複数の磁気抵抗素子の磁化方向を求める磁化方向算出工程と、前記磁化方向算出工程で算出した前記磁化方向と前記各磁気抵抗素子の異方性磁界の強さとを用いて、前記外部磁界の磁界方向を求める磁界方向算出工程と、を有する、磁気センサユニットを用いた磁界方向検出方法。 A magnetic field using a magnetic sensor unit including a plurality of magnetoresistive elements arranged along at least two different directions and magnetized by an external magnetic field, and a power supply unit that applies a voltage to the plurality of magnetoresistive elements. In the direction detection method, 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 detection method using a magnetic sensor unit.
  6. 請求項５に記載の磁気センサユニットを用いた磁界方向検出方法において、前記磁界方向算出工程では、（１）式を用いて、前記外部磁界の前記磁界方向を算出する、磁気センサユニットを用いた磁界方向検出方法。

    φ＝ａｒｃｃｏｓ（ｓｉｎ２θ／（２ｈ））＋θ　　（１）

    ｈ＝Ｈ／Ｈａ

    φ：外部磁界の磁界方向（ｒａｄ）

    θ：各磁気抵抗素子の磁化方向（ｒａｄ）

    Ｈ：外部磁界の強さ（Ａ／ｍ）

    Ｈａ：各磁気抵抗素子の異方性磁界の強さ（Ａ／ｍ）     6. The magnetic field direction detection method using the magnetic sensor unit according to claim 5, wherein the magnetic field direction calculation step uses a magnetic sensor unit that calculates the magnetic field direction of the external magnetic field using equation (1). Magnetic field direction detection method.

    φ = arccos (sin 2 θ / (2h)) + θ (1)

    h = H / Ha

    φ: Magnetic field direction of external magnetic field (rad)

    θ: Magnetization direction (rad) of each magnetoresistive element

    H: Strength of external magnetic field (A / m)

    Ha: Strength of anisotropic magnetic field of each magnetoresistive element (A / m)
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