CN116263318A - Angle sensor device and angle detection device - Google Patents

Abstract

The magnetic field generator includes an N pole and an S pole disposed at positions sandwiching the rotation axis. The first magnetic sensor and the second magnetic sensor are respectively disposed so as to sandwich the rotary shaft outside the outer peripheral surface of the magnetic field generator. The first detection circuit of the first magnetic sensor and the third detection circuit of the second magnetic sensor are configured such that the detection signals of the first and third detection circuits are maximized when the first magnetic field component in the X direction is applied. The second detection circuit of the first magnetic sensor and the fourth detection circuit of the second magnetic sensor are configured such that the detection signals of the second and fourth detection circuits are maximized when the second magnetic field component in the-Y direction is applied.

Description

Angle sensor device and angle detection device

Technical Field

The present invention relates to an angle sensor device and an angle detection device that generate a detection value having a correspondence relation with an angle of a detection object based on a magnetic field generated by a magnetic field generator.

Background

In recent years, angle sensor devices that generate an angle detection value having a correspondence relation with an angle of a detection object have been widely used for various applications such as detection of a rotational position of a steering wheel or a power steering motor of an automobile. As the angle sensor device, for example, there is a magnetic angle sensor device using a magnetic sensor. In general, a magnetic field generator for generating a detection target magnetic field whose direction is rotated in conjunction with rotation or linear motion of a target is provided in a magnetic angle sensor device. The magnetic field generator is for example a magnet. The angle of the detection target in the magnetic angle sensor device corresponds to the angle formed by the direction of the detection target magnetic field at the reference position with respect to the reference direction.

In the specification of chinese patent application publication No. 101939623a, a rotation angle inspection device configured such that one sensor device faces a magnet rotor at a predetermined interval is described. The sensor device includes two bridge circuits each including four magnetoresistance effect elements, and is configured to be capable of measuring a periodic variation of magnetic flux in a radial direction and a rotational direction of the magnet rotor as an output voltage.

Japanese patent application laid-open No. 2012-37467 discloses a rotating magnetic field sensor including a magnetic field generating unit that generates a rotating magnetic field, a first detecting unit that detects the rotating magnetic field at a first position, and a second detecting unit that detects the rotating magnetic field at a second position. The first detection unit and the second detection unit each include: two detection circuits including two bridge circuits each composed of four magnetoresistance effect elements; and an arithmetic circuit that generates an angle detection value based on the output signals of the two detection circuits.

In an angle sensor device including a magnetic field generator and a magnetic sensor as described in japanese patent application laid-open No. 101939623a and japanese patent application laid-open No. 2012-37467, correction of a detection signal is generally performed before a product is shipped in order to reduce an error in an angle detection value. However, depending on the accuracy of setting the angle sensor device, the relative positional relationship between the magnetic field generator and the magnetic sensor may deviate. When the relative positional relationship is deviated, the detection signal may deviate, and as a result, an error in the angle detection value may become large.

Further, the technical problem described in japanese patent application laid-open No. 2012-37467 is to reduce the error of the detection angle caused by the noise magnetic field other than the rotating magnetic field, rather than reducing the error of the detection angle caused by the positional displacement of the magnetic field generator and the first and second detection units.

Disclosure of Invention

The invention aims to provide an angle sensor device and an angle detection device, which can reduce errors caused by position deviation of a magnetic field generator and a magnetic sensor.

The present invention provides an angle sensor device, which comprises: a magnetic field generator configured to generate a target magnetic field and to rotate about a rotation axis; the first magnetic sensor and the second magnetic sensor are disposed at a first position and a second position, respectively, on the outer side of the outer peripheral surface of the magnetic field generator, sandwiching the rotation shaft, when viewed from a direction parallel to the rotation shaft. The magnetic field generator includes a plurality of magnetic poles arranged along the rotation axis in the axial direction. The plurality of magnetic poles include two magnetic poles which are arranged so as to sandwich the rotation axis when viewed in a direction parallel to the rotation axis and have magnetization directions opposite to each other.

The first magnetic sensor includes: a first detection circuit and a second detection circuit configured to detect the object magnetic field at the first position and output detection signals, respectively; and a first arithmetic circuit configured to calculate a first angle detection value, which is a detection value of the rotation angle of the magnetic field generator, based on the detection signals of the first detection circuit and the second detection circuit. The second magnetic sensor includes: a third detection circuit and a fourth detection circuit configured to detect the object magnetic field at the second position and output detection signals, respectively; and a second arithmetic circuit configured to calculate a second angle detection value, which is a detection value of the rotation angle, based on the detection signals of the third detection circuit and the fourth detection circuit.

The first detection circuit and the third detection circuit are each configured to have sensitivity in a first direction, and are configured to have a maximum detection signal when a first magnetic field component in a specific one direction parallel to the first direction is applied. The second detection circuit and the fourth detection circuit are each configured to have sensitivity in the second direction, and are each configured to have a maximum detection signal when a second magnetic field component in a specific one direction parallel to the second direction is applied.

In the angle sensor device according to the present invention, the second position may be a position rotated 180 ° about the rotation axis from the first position when viewed from a direction parallel to the rotation axis.

In the angle sensor device of the present invention, the magnetic field generator may intersect with an imaginary plane perpendicular to the rotation axis as a whole when viewed from a direction perpendicular to the rotation axis. The distance from the first position to the virtual plane and the distance from the second position to the virtual plane may be equal to each other.

In the angle sensor device according to the present invention, the first position and the second position may be the same position in a direction parallel to the rotation axis. Alternatively, the first position and the second position may be different positions from each other in a direction parallel to the rotation axis.

In the angle sensor device according to the present invention, the magnetic field generator may include an odd number of two magnetic poles as the plurality of magnetic poles.

The angle sensor device of the present invention may further include a substrate on which the first magnetic sensor and the second magnetic sensor are mounted. The substrate may have a first surface and a second surface at both ends in a direction parallel to the rotation axis. The first magnetic sensor may be mounted on the first surface. The second magnetic sensor may be mounted on the first surface or the second surface.

The angle sensor device of the present invention may further include a first substrate on which the first magnetic sensor is mounted and a second substrate on which the second magnetic sensor is mounted.

The angle sensor device of the present invention may further include a processor that generates a corrected detection value based on the first angle detection value and the second angle detection value.

The angle sensor device of the present invention may further include a holder for accommodating the magnetic field generator, the first magnetic sensor, and the second magnetic sensor.

The invention provides an angle detection device, which is provided with an angle sensor device and a shaft for fixing a magnetic field generator.

In the angle sensor device and the angle detection device according to the present invention, the first detection circuit and the third detection circuit are configured to have sensitivity in the same direction, and are configured to have the largest detection signal when the first magnetic field component in the same direction is applied. The second detection circuit and the fourth detection circuit are configured to have sensitivity in the same direction, and are configured to have the largest detection signal when the second magnetic field component in the same direction is applied. Thus, according to the present invention, errors caused by positional displacement of the magnetic field generator and the magnetic sensor can be reduced.

Other objects, features and advantages of the present invention will become more fully apparent from the following description.

Drawings

Fig. 1 is a perspective view showing an angle sensor device according to a first embodiment of the present invention.

Fig. 2 is a plan view showing a main part of an angle sensor device according to a first embodiment of the present invention.

Fig. 3 is a side view showing a main part of an angle sensor device according to a first embodiment of the present invention.

Fig. 4 is an explanatory diagram showing the definition of directions and angles in the first embodiment of the present invention.

Fig. 5 is a block diagram showing the configuration of the first and second magnetic sensors in the first embodiment of the present invention.

Fig. 6 is a circuit diagram showing an example of the configuration of the first detection circuit in the first embodiment of the present invention.

Fig. 7 is a circuit diagram showing an example of the configuration of the second detection circuit in the first embodiment of the present invention.

Fig. 8 is a perspective view showing a part of one of the magnetic detection elements shown in fig. 6 and 7.

Fig. 9 is a characteristic diagram showing the first angle detection value and the error of the detection value in the first state.

Fig. 10 is a characteristic diagram showing the first angle detection value and the error of the detection value in the second state.

Fig. 11 is a characteristic diagram showing the first angle detection value and the error of the detection value in the third state.

Fig. 12 is a characteristic diagram showing the first angle detection value and the error of the detection value in the fourth state.

Fig. 13 is a plan view showing a first modification of the angle sensor device according to the first embodiment of the present invention.

Fig. 14 is a plan view showing a second modification of the angle sensor device according to the first embodiment of the present invention.

Fig. 15 is a side view showing a main part of an angle sensor device according to a second embodiment of the present invention.

Fig. 16 is a side view showing a main part of an angle sensor device according to a third embodiment of the present invention.

Fig. 17 is a plan view showing a main part of an angle sensor device according to a fourth embodiment of the present invention.

Detailed Description

First embodiment

First, a schematic configuration of an angle sensor device and an angle detection device according to a first embodiment of the present invention will be described with reference to fig. 1. Fig. 1 is a perspective view showing an angle sensor device according to the present embodiment. The angle detection device 100 of the present embodiment includes the angle sensor device 1 of the present embodiment. The angle sensor device 1 is in particular a magnetic angle sensor device.

The angle sensor device 1 includes a magnetic field generator 5. The magnetic field generator 5 has a ring shape centered on the rotation axis, and is configured to generate a target magnetic field, which is a magnetic field to be detected, and to rotate around the rotation axis. In the present embodiment, in particular, a cylindrical fixing member 4 is fixed to the inner side of the magnetic field generator 5. The fixing member 4 is fixed to the magnetic field generator 5 by, for example, insert molding or adhesive bonding. A shaft 101 is inserted and fixed inside the fixing member 4. The shaft 101 is fixed to the fixing member 4 by, for example, press fitting or bonding.

The shaft 101 may be, for example, a shaft of a motor not shown, or may be a shaft configured to rotate together with the shaft of the motor. The magnetic field generator 5 and the shaft 101 are integrally formed and rotated by the fixing member 4. The angle detection device 100 of the present embodiment includes a shaft 101 in addition to the angle sensor device 1.

Hereinafter, the angle of the detection target of the angle sensor device 1 and the angle detection device 100 is referred to as a target angle, and is denoted by a symbol θ. The object angle θ of the present embodiment corresponds to the rotation angle θm of the magnetic field generator 5 and the shaft 101.

The angle sensor device 1 further includes the first magnetic sensor 10, the second magnetic sensor 20, and the substrate 6 on which the first magnetic sensor 10 and the second magnetic sensor 20 are mounted. The substrate 6 has a U-shaped planar shape as viewed from a direction parallel to the rotation axis, sandwiching the magnetic field generator 5 and the shaft 101. The first magnetic sensor 10 and the second magnetic sensor 20 are mounted in the vicinity of both ends of the substrate 6 in the longitudinal direction. In fig. 1, symbol 40 denotes a plurality of terminals connected to the substrate 6 by soldering or pressing, for example, in order to take out signals from the substrate 6.

The angle sensor device 1 further includes a holder 7 that accommodates the magnetic field generator 5, the first magnetic sensor 10, and the second magnetic sensor 20. In the present embodiment, in particular, the holder 7 is partitioned into a first housing portion 7a housing the magnetic field generator 5 and a second housing portion 7b housing the first and second magnetic sensors 10,20, which are the substrates 6. The first and second housing portions 7a, 7b of the holder 7 may be covered with a cover, not shown.

The angle sensor device 1 further comprises a connector 8 for connecting the first and second magnetic sensors 10, 20 to the outside of the angle sensor device 1.

Next, the structure of the magnetic field generator 5 and the arrangement of the first and second magnetic sensors 10, 20 will be described in detail with reference to fig. 2 and 3. Fig. 2 shows a top view of the main part of the angle sensor device 1. Fig. 3 is a side view showing a main part of the angle sensor device 1. In fig. 2 and 3, symbol C denotes a rotation axis. In fig. 2 and 3, the fixing member 4 is omitted for convenience.

The magnetic field generator 5 includes a plurality of magnetic poles arranged along the axial direction of the rotation axis C. The plurality of magnetic poles include two magnetic poles, i.e., an N pole and an S pole, which are arranged so as to sandwich the rotation axis C and have opposite magnetization directions, as viewed in a direction parallel to the rotation axis C. The magnetic field generator 5 may also include an odd number of N and S poles as a plurality of magnetic poles. In this embodiment, the magnetic field generator 5 includes a set of N-pole and S-pole.

In fig. 3, symbol PL0 represents a plane intersecting the center of the magnetic field generator 5 in the direction parallel to the rotation axis C, out of imaginary planes perpendicular to the rotation axis C. The magnetic field generator 5 intersects the virtual plane PL0 as a whole when viewed from a direction perpendicular to the rotation axis C (for example, a direction perpendicular to the paper surface).

Here, two positions on the outer side of the outer peripheral surface of the magnetic field generator 5 sandwiching the rotation axis C when viewed from a direction parallel to the rotation axis C are referred to as a first position P1 and a second position P2, respectively. The first magnetic sensor 10 is disposed at a first position P1. The second magnetic sensor 20 is disposed at the second position P2. In the present embodiment, the second position P2 is a position rotated 180 ° around the rotation axis C from the first position P1, particularly when viewed from a direction parallel to the rotation axis C.

As shown in fig. 3, the first position P1 and the second position P2 are the same positions in the direction parallel to the rotation axis C. In the example shown in fig. 3, the virtual plane PL0 intersects the first position P1 and the second position P2. Therefore, the distance from the first position P1 to the virtual plane PL0 and the distance from the second position P2 to the virtual plane PL0 are both 0.

The substrate 6 has a first surface 6a and a second surface 6b at both ends in a direction parallel to the rotation axis C. The first magnetic sensor 10 and the second magnetic sensor 20 are mounted on the first surface 6a, respectively.

The first magnetic sensor 10 detects the object magnetic field at the first position P1, and the second magnetic sensor 20 detects the object magnetic field at the second position P2. Hereinafter, the object magnetic field at the first position P1 is referred to as a first partial magnetic field MFa, and the object magnetic field at the second position P2 is referred to as a second partial magnetic field MFb. When the magnetic field generator 5 rotates about the rotation axis C, the first partial magnetic field MFa rotates about the first position P1, and the second partial magnetic field MFb rotates about the second position P2. In fig. 2, the first partial magnetic field MFa is depicted at a position away from the first position P1 for convenience. Also, in fig. 2, the second partial magnetic field MFb is depicted at a position away from the second position P2 for convenience.

Here, the definition of the direction and angle in the present embodiment will be described with reference to fig. 2 to 4. First, a direction parallel to the rotation axis C shown in fig. 3 and directed upward from the lower side of fig. 3 is referred to as a Z direction. In fig. 2, the Z direction is shown from the depth of fig. 2 toward the near side. Next, two directions perpendicular to the Z direction and orthogonal to each other are referred to as an X direction and a Y direction. In fig. 2 and 3, the X direction is shown as a direction toward the right. In fig. 2, the Y direction is shown as the upward direction, and in fig. 3, the Y direction is shown as the direction from the front of fig. 3 toward the depth. The direction opposite to the X direction is referred to as the-X direction, the direction opposite to the Y direction is referred to as the-Y direction, and the direction opposite to the Z direction is referred to as the-Z direction.

In fig. 4, symbol PL1 represents a virtual plane intersecting the first position P1, out of virtual planes perpendicular to the rotation axis C. Hereinafter, this virtual plane will be referred to as a first reference plane PL1. The first magnetic sensor 10 is configured to actually detect a component in the first partial magnetic field MFa in a direction parallel to the first reference plane PL1. In the following description, the direction of the first partial magnetic field MFa means a direction lying in the first reference plane PL1.

In fig. 4, symbol PL2 represents a virtual plane intersecting the second position P2, out of virtual planes perpendicular to the rotation axis C. Hereinafter, this virtual plane will be referred to as a second reference plane PL2. The second magnetic sensor 20 is configured to actually detect a component in the second partial magnetic field MFb in a direction parallel to the second reference plane PL2. In the following description, the direction of the second partial magnetic field MFb refers to a direction lying in the second reference plane PL2.

In the present embodiment, in particular, the virtual plane PL0, the first reference plane PL1, and the second reference plane PL2 are substantially the same plane.

The directions of the first and second partial magnetic fields MFa, MFb are each set to be directions rotated in the counterclockwise direction in fig. 4. As shown in fig. 4, the angle formed by the direction of the first partial magnetic field MFa with respect to the Y direction is denoted by a symbol θ1, and the angle formed by the direction of the second partial magnetic field MFb with respect to the Y direction is denoted by a symbol θ2. The angles θ1, θ2 are expressed as positive values when viewed in the counterclockwise direction from the Y direction, and the angles θ1, θ2 are expressed as negative values when viewed in the clockwise direction from the Y direction.

Further, when the magnetic field generator 5 and the shaft 101 are viewed from a position separated in the Z direction, if the magnetic field generator 5 and the shaft 101 are rotated in the clockwise direction, the directions of the first and second partial magnetic fields MFa, MFb are each rotated in the counterclockwise direction in fig. 4.

Next, the structure of the first and second magnetic sensors 10, 20 will be described in detail with reference to fig. 5. Fig. 5 is a block diagram showing the configuration of the first and second magnetic sensors 10 and 20.

The first magnetic sensor 10 includes a first detection circuit 11 and a second detection circuit 12. The first detection circuit 11 and the second detection circuit 12 are included in the portions denoted by reference numeral 10 in fig. 1 to 3. The first detection circuit 11 and the second detection circuit 12 are configured to detect the first partial magnetic field MFa and output detection signals S1, S2, respectively.

The second magnetic sensor 20 includes a third detection circuit 21 and a fourth detection circuit 22. The third detection circuit 21 and the fourth detection circuit 22 are included in the portions denoted by reference numeral 20 in fig. 1 to 3. The third detection circuit 21 and the fourth detection circuit 22 are configured to detect the second partial magnetic field MFb and output detection signals S3, S4, respectively.

The first detection circuit 11 and the third detection circuit 21 are each configured to have sensitivity in the first direction, and are configured to maximize the detection signal S1 of the first detection circuit 11 and the detection signal S3 of the third detection circuit 21, respectively, when a first magnetic field component in a specific one direction parallel to the first direction is applied. Hereinafter, a specific direction parallel to the first direction is referred to as a direction D1.

In the present embodiment, in particular, the first direction is a direction parallel to the X direction, and the direction D1 is the X direction. The first detection circuit 11 detects a component of the first partial magnetic field MFa in a direction parallel to the X direction, and generates a detection signal S1 having a correspondence relationship with the sine of the angle θ1. The detection signal S1 may also have a correspondence with the intensity of a component of the first partial magnetic field MFa in a direction parallel to the X direction. In addition, the third detection circuit 21 detects a component of the second partial magnetic field MFb in a direction parallel to the X direction, and generates a detection signal S3 having a correspondence relationship with the sine of the angle θ2. The detection signal S3 may also have a correspondence with the intensity of the component of the second partial magnetic field MFb in the direction parallel to the X direction.

The second detection circuit 12 and the fourth detection circuit 22 are each configured to have sensitivity in the second direction, and are configured to have the largest detection signal S2 of the second detection circuit 12 and the largest detection signal S4 of the fourth detection circuit 22 when a second magnetic field component in a specific one direction parallel to the second direction is applied. Hereinafter, a specific direction parallel to the second direction is referred to as a direction D2.

In this embodiment, in particular, the second direction is a direction parallel to the Y direction, and the direction D2 is a-Y direction. The first direction and the second direction are orthogonal to each other. The direction D1 and the direction D2 are also orthogonal to each other. The second detection circuit 12 detects a component of the first partial magnetic field MFa in a direction parallel to the Y direction, and generates a detection signal S2 having a correspondence relationship with the cosine of the angle θ1. The detection signal S2 may also have a correspondence relationship with the intensity of the component of the first partial magnetic field MFa in the direction parallel to the Y direction. In addition, the fourth detection circuit 22 detects a component of the second partial magnetic field MFb in a direction parallel to the Y direction, and generates a detection signal S4 having a correspondence relationship with the cosine of the angle θ2. The detection signal S4 may also have a correspondence relationship with the intensity of the component of the second partial magnetic field MFb in the direction parallel to the Y direction.

When the magnetic field generator 5 and the shaft 101 shown in fig. 1 to 3 rotate at a predetermined period T, the object angle θ changes at the period T. In this case, the detection signals S1 to S4 each periodically change with the period T. The phases of the detection signal S1 and the detection signal S3 are the same. The phases of the detection signal S2 and the detection signal S4 are the same. The phase of the detection signal S2 differs from the phase of the detection signal S1 by an odd multiple of 1/4 of the period T. The phase of the detection signal S4 differs from the phase of the detection signal S3 by an odd multiple of 1/4 of the period T. The relationship between the phases of the detection signals may be slightly different from the above-described relationship from the viewpoint of the accuracy of the production of the first to fourth detection circuits 11, 12, 21, 22, and the like.

The first magnetic sensor 10 further includes a first arithmetic circuit 13. The first arithmetic circuit 13 generates a first angle detection value θ1s, which is a detection value of the object angle θ, based on the detection signals S1 and S2. The first arithmetic circuit 13 may be integrated with the first and second detection circuits 11 and 12 (the portion indicated by the reference numeral 10 in fig. 1 to 3), or may be separate from the first and second detection circuits 11 and 12.

The second magnetic sensor 20 further includes a second arithmetic circuit 23. The second arithmetic circuit 23 generates a second angle detection value θ2s, which is a detection value of the target angle θ, based on the detection signals S3 and S4. The second arithmetic circuit 23 may be integrated with the third and fourth detection circuits 21 and 22 (the portion denoted by reference numeral 20 in fig. 1 to 3), or may be separate from the third and fourth detection circuits 21 and 22.

The angle sensor device 1 further includes a processor 30. The processor 30 generates a detection value θs in which the object angle θ is corrected, based on the first angle detection value θ1s and the second angle detection value θ2s. The processor 30 may be mounted on the substrate 6 shown in fig. 1, or may not be mounted on the substrate 6 shown in fig. 1. In the case where the processor 30 is mounted on the substrate 6, the processor 30 may be integrated with the first and second arithmetic circuits 13 and 23, or may be separated from the first and second arithmetic circuits 13 and 23. When the processor 30 is not mounted on the substrate 6, the processor 30 may be connected to the first and second arithmetic circuits 13 and 23 via signal lines, not shown, connected to the connector 8 shown in fig. 1.

The first and second arithmetic circuits 13 and 23 can be realized by Application Specific Integrated Circuits (ASIC), for example. The processor 30 can be implemented by an ASIC or a microcomputer, for example.

Next, the configuration of the first to fourth detection circuits 11, 12, 21, 22 will be described. The first to fourth detection circuits 11, 12, 21, 22 each include at least one magnetic detection element. The at least one magnetic detection element may also comprise at least one magneto-resistive effect element. The magneto-resistive effect element may be a GMR (giant magneto-resistive effect) element, a TMR (tunnel magneto-resistive effect) element, or an AMR (anisotropic magneto-resistive effect) element. The at least one magnetic detection element may include at least one element for detecting a magnetic field other than a magnetoresistance effect element, such as a hall element.

Fig. 6 shows an example of a specific configuration of the first detection circuit 11. In this example, the first detection circuit 11 has a wheatstone bridge circuit 14 and a differential detector 15. The wheatstone bridge circuit 14 includes four magnetic detection elements R11, R12, R13, R14, a power supply port V1, a ground port G1, and two output ports E11, E12. The magnetic detection element R11 is provided between the power supply port V1 and the output port E11. The magnetic detection element R12 is disposed between the output port E11 and the ground port G1. The magnetic detection element R13 is disposed between the output port E12 and the ground port G1. The magnetic detection element R14 is provided between the power supply port V1 and the output port E12. A voltage or a current of a predetermined magnitude is applied to the power supply port V1. The ground port G1 is connected to ground.

The third detection circuit 21 has the same structure as the first detection circuit 11. Therefore, in the following description, the same reference numerals as those of the first detection circuit 11 are used for the components of the third detection circuit 21.

Fig. 7 shows an example of a specific configuration of the second detection circuit 12. In this example, the second detection circuit 12 has a wheatstone bridge circuit 24 and a differential detector 25. The wheatstone bridge circuit 24 includes four magnetic detection elements R21, R22, R23, R24, a power supply port V2, a ground port G2, and two output ports E21, E22. The magnetic detection element R21 is provided between the power supply port V2 and the output port E21. The magnetic detection element R22 is disposed between the output port E21 and the ground port G2. The magnetic detection element R23 is disposed between the output port E22 and the ground port G2. The magnetic detection element R24 is disposed between the power supply port V2 and the output port E22. A voltage or a current of a predetermined magnitude is applied to the power supply port V2. The ground port G2 is connected to ground.

The fourth detection circuit 22 has the same structure as the second detection circuit 12. Therefore, in the following description, the same reference numerals as those of the second detection circuit 12 are used for the components of the fourth detection circuit 22.

In the present embodiment, each of the magnetic detection elements R11 to R14 and R21 to R24 includes a plurality of magnetoresistance effect elements (MR elements) connected in series. The plurality of MR elements are, for example, spin valve type MR elements. The spin valve type MR element comprises: a magnetization fixed layer having a magnetization whose direction is fixed; a free layer which is a magnetic layer having a magnetization whose direction is changeable according to a subject magnetic field; and a gap layer disposed between the magnetization fixed layer and the free layer. The spin valve type MR element may be a TMR (tunnel magnetoresistance effect) element or a GMR (giant magnetoresistance effect) element. In the TMR element, the gap layer is a tunnel barrier layer. In the GMR element, the gap layer is a nonmagnetic conductive layer. In the spin valve type MR element, the resistance value varies depending on the angle formed by the magnetization direction of the free layer with respect to the magnetization direction of the magnetization fixed layer, and the resistance value becomes the minimum value when the angle is 0 ° and the resistance value becomes the maximum value when the angle is 180 °. In fig. 6 and 7, solid arrows indicate magnetization directions of magnetization fixed layers in the MR element, and open arrows indicate magnetization directions of free layers in the MR element.

In the first detection circuit 11, the magnetization direction of the magnetization pinned layer in the plurality of MR elements included in the magnetic detection elements R11, R13 is the X direction, and the magnetization direction of the magnetization pinned layer in the plurality of MR elements included in the magnetic detection elements R12, R14 is the-X direction. In this case, the potential difference of the output ports E11, E12 varies according to the sine of the angle θ1. The differential detector 15 outputs a signal corresponding to the potential difference of the output ports E11, E12 as the detection signal S1. Therefore, the detection signal S1 has a correspondence relationship with the sine of the angle θ1. The detection signal S1 is maximum when the X-direction magnetic field component is applied to the first detection circuit 11, and is minimum when the-X-direction magnetic field component is applied to the first detection circuit 11.

In the second detection circuit 12, the magnetization direction of the magnetization pinned layer in the plurality of MR elements included in the magnetic detection elements R21, R23 is the-Y direction, and the magnetization direction of the magnetization pinned layer in the plurality of MR elements included in the magnetic detection elements R22, R24 is the Y direction. In this case, the potential difference of the output ports E21, E22 varies according to the cosine of the angle θ1. The differential detector 25 outputs a signal corresponding to the potential difference of the output ports E21, E22 as the detection signal S2. Therefore, the detection signal S2 has a correspondence relationship with the cosine of the angle θ1. The detection signal S2 is maximum when the magnetic field component in the-Y direction is applied to the second detection circuit 12, and is minimum when the magnetic field component in the Y direction is applied to the second detection circuit 12.

In the third detection circuit 21, the potential difference of the output ports E11, E12 varies according to the sine of the angle θ2. The differential detector 15 outputs a signal corresponding to the potential difference of the output ports E11, E12 as the detection signal S3. Therefore, the detection signal S3 has a correspondence relationship with the sine of the angle θ2. The detection signal S3 is maximum when the X-direction magnetic field component is applied to the third detection circuit 21, and minimum when the-X-direction magnetic field component is applied to the third detection circuit 21.

In the fourth detection circuit 22, the potential difference of the output ports E21, E22 varies according to the cosine of the angle θ2. The differential detector 25 outputs a signal corresponding to the potential difference of the output ports E21, E22 as the detection signal S4. Therefore, the detection signal S4 has a correspondence relationship with the cosine of the angle θ2. The detection signal S4 is maximum when the magnetic field component in the-Y direction is applied to the fourth detection circuit 22, and is minimum when the magnetic field component in the Y direction is applied to the fourth detection circuit 22.

In addition, the magnetization directions of the magnetization pinned layers in the plurality of MR elements in the first to fourth detection circuits 11, 12, 21, 22 may be slightly deviated from the above-described directions from the viewpoint of precision in manufacturing the MR elements, and the like.

An example of the structure of the magnetic detection element will be described with reference to fig. 8. Fig. 8 is a perspective view showing a part of one magnetic detection element in the first and second detection circuits 11 and 12 shown in fig. 6 and 7. In this example, one magnetic detection element has a plurality of lower electrodes 41, a plurality of MR elements 50, and a plurality of upper electrodes 42. The plurality of lower electrodes 41 are disposed on a substrate, not shown. Each lower electrode 41 has an elongated shape. A gap is formed between two lower electrodes 41 adjacent in the longitudinal direction of the lower electrodes 41. As shown in fig. 8, MR elements 50 are disposed on the upper surface of the lower electrode 41 in the vicinity of both ends in the longitudinal direction. The MR element 50 includes a free layer 51, a gap layer 52, a magnetization fixed layer 53, and an antiferromagnetic layer 54, which are laminated in this order from the lower electrode 41 side. The free layer 51 is electrically connected to the lower electrode 41. The antiferromagnetic layer 54 is made of an antiferromagnetic material, and exchange coupling is generated between the antiferromagnetic layer and the magnetization fixed layer 53, thereby fixing the magnetization direction of the magnetization fixed layer 53. The plurality of upper electrodes 42 are disposed on the plurality of MR elements 50. Each of the upper electrodes 42 has an elongated shape, and is disposed on two lower electrodes 41 adjacent in the longitudinal direction of the lower electrode 41, and the antiferromagnetic layers 54 of the two adjacent MR elements 50 are electrically connected to each other. With this structure, the magnetic detection element shown in fig. 8 has a plurality of MR elements 50 connected in series with a plurality of lower electrodes 41 and a plurality of upper electrodes 42.

The arrangement of the layers 51 to 54 in the MR element 50 may be reversed from the arrangement shown in fig. 8. The magnetization pinned layer 53 may be a so-called self-pinning pinned layer (Synthetic Ferri Pinned layer, SFP layer). The self-pinned fixed layer has a laminated ferromagnetic (ferri) structure in which a ferromagnetic layer, a nonmagnetic intermediate layer, and a ferromagnetic layer are laminated, and the two ferromagnetic layers are antiferromagnetically coupled. In the case where the magnetization pinned layer 53 is a self-pinned layer, the antiferromagnetic layer 54 may be omitted.

Next, a method for calculating the first and second angle detection values θ1s and θ2s will be described. The first arithmetic circuit 13 of the first magnetic sensor 10 calculates θ1s in a range of 0 ° or more and less than 360 ° according to the following equation (1), for example. In addition, "atan" means arctangent.

θ1s＝atan(S1/S2)+180°…(1)

The second arithmetic circuit 23 of the second magnetic sensor 20 calculates θ2s in a range of 0 ° or more and less than 360 ° by the following equation (2), for example.

θ2s＝atan(S3/S4)+180°…(2)

Next, a method for calculating the detection value θs will be described. The processor 30 calculates the detection value θs by an operation including a sum of the first angle detection value θ1s and the second angle detection value θ2s. In the present embodiment, the processor 30 calculates θs by, for example, the following equation (3).

θs＝(θ1s+θ2s)/2…(3)

Next, the operation and effects of the angle sensor device 1 and the angle detection device 100 according to the present embodiment will be described. In the present embodiment, when the relative positional relationship between the magnetic field generator 5 and the first and second magnetic sensors 10, 20 is deviated from a predetermined position (designed position), the first to fourth detection circuits 11, 12, 21, 22 are configured such that one of the first angle detection value θ1s and the second angle detection value θ2s increases and the other decreases. Specifically, as described above, the first detection circuit 11 and the third detection circuit 21 are each configured to have sensitivity in the direction parallel to the X direction, and are configured to have maximum detection signals S1, S3 of the first detection circuit 11 and the third detection circuit 21, respectively, when the first magnetic field component in the X direction is applied, and the second detection circuit 12 and the fourth detection circuit 22 are each configured to have sensitivity in the direction parallel to the Y direction, and are configured to have maximum detection signals S2, S4 of the second detection circuit 12 and the fourth detection circuit 22, respectively, when the second magnetic field component in the-Y direction is applied. Thus, according to the present embodiment, the error of the detection value θs caused by the positional displacement of the magnetic field generator 5 and the first and second magnetic sensors 10 and 20 can be reduced.

Here, the deviation of the first and second angle detection values θ1s, θ2s due to the positional deviation of the magnetic field generator 5 and the first and second magnetic sensors 10, 20 will be described. Table 1 shows the deviations of the first and second angle detection values θ1s, θ2s when the rotation angles θm of the magnetic field generator 5 and the shaft 101 are 0 °, 45 °, 90 °, 135 °, 180 °, 225 °, 270 °, and 315 °, respectively. Here, the rotation angle θm in a state where the N pole is located on the-Y direction side of the XZ plane including the rotation axis and the S pole is located on the Y direction side of the XZ plane including the rotation axis is set to 0 °. When the magnetic field generator 5 and the shaft 101 are viewed from a position separated in the Z direction, the magnetic field generator 5 and the shaft 101 rotate in the clockwise direction.

In table 1, "first case" is a case where the magnetic field generator 5 is deviated from the predetermined position in the-Y direction, and "second case" is a case where the magnetic field generator 5 is deviated from the predetermined position in the X direction. The predetermined position is a designed position. In table 1, θ1s or θ2s indicates that the magnetic field generator 5 increases from the state at the predetermined position, θ1s or θ2s indicates that the magnetic field generator 5 decreases from the state at the predetermined position, and "0" indicates that the magnetic field generator 5 does not deviate from the state nor increases nor decreases.

TABLE 1

For example, when the magnetic field generator 5 is deviated from the predetermined position in the-Y direction in a state where the rotation angle θm is 90 ° (first case), the first partial magnetic field MFa is inclined from the-X direction toward the-Y direction, and the second partial magnetic field MFb is inclined from the-X direction toward the Y direction. As a result, the first angle detection value θ1s is larger than 90 °, and the second angle detection value θ2s is smaller than 90 °. When the magnetic field generator 5 is deviated from the predetermined position in the-Y direction (first case) with the rotation angle θm being 180 °, the first partial magnetic field MFa is inclined from the-Y direction toward the X direction, and the second partial magnetic field MFb is inclined from the-Y direction toward the-X direction. As a result, the first angle detection value θ1s is larger than 180 °, and the second angle detection value θ2s is smaller than 180 °.

For example, when the magnetic field generator 5 is deviated from the predetermined position in the X direction in a state where the rotation angle θm is 45 ° (second case), the first partial magnetic field MFa is inclined in the-X direction from the direction rotated by 45 ° from the Y direction toward the-X direction, and the second partial magnetic field MFb is inclined in the Y direction from the direction rotated by 45 ° from the Y direction toward the-X direction. As a result, the first angle detection value θ1s is larger than 45 °, and the second angle detection value θ2s is smaller than 45 °. When the magnetic field generator 5 is deviated from the predetermined position in the X direction (second case) with the rotation angle θm of 135 °, the first partial magnetic field MFa is inclined in the-X direction from the direction rotated by 45 ° from the-X direction toward the-Y direction, and the second partial magnetic field MFb is inclined in the-Y direction from the direction rotated by 45 ° from the-X direction toward the-Y direction. As a result, the first angle detection value θ1s is smaller than 135 °, and the second angle detection value θ2s is larger than 135 °.

As described above, in the present embodiment, even in either the first case or the second case, when one of the first and second angle detection values θ1s and θ2s increases, the other decreases. In the case where the magnetic field generator 5 is deviated from the predetermined position in the-Y direction in the state where the rotation angle θm is 0 ° (first case), the second angle detection value θ2s is changed from 0 ° to an angle close to 360 ° (for example 359 °). In table 1, for convenience, when the second angle detection value θ2s changes as described above, it is considered that the second angle detection value θ2s decreases.

In contrast to the first case, when the magnetic field generator 5 is deviated from the predetermined position in the Y direction, the first angle detection value θ1s decreases and the second angle detection value θ2s increases. In contrast to the second case, when the magnetic field generator 5 is deviated from the predetermined position in the-X direction, the rotation angle θm increased in the second case by the first and second angle detection values θ1s, θ2s decreases, and the rotation angle θm decreased in the second case increases.

As described above, in the present embodiment, even when the relative positional relationship between the magnetic field generator 5 and the first and second magnetic sensors 10 and 20 is deviated, the first and second angle detection values θ1s and θ2s are changed to deviate against each other. Thus, according to the present embodiment, the error of the detection value θs caused by the positional displacement of the magnetic field generator 5 and the first and second magnetic sensors 10 and 20 can be reduced.

Next, the experimental result showing the error reduction of the detection value θs will be described. In the experiment, the error of each of the first angle detection value θ1s and the detection value θs when the magnetic field generator 5 is at different positions was obtained using the manufactured angle sensor device 1. The main parameters of the manufactured angle sensor device 1 are as follows. The outer diameter of the magnetic field generator 5 is 20mm. The inner diameter of the magnetic field generator 5 is 16mm. The first position P1 and the second position P2 are spaced 29mm apart.

In the experiment, the magnetic field generator 5 was rotated in a state in which the rotation center of the magnetic field generator 5 was deviated from the following first to fourth positions, and the first angle detection value θ1s and the detection value θs were obtained. Here, the predetermined position is set to be the midpoint between the first position P1 and the second position P2. The first position is a position offset from the predetermined position by 0.1mm in the X direction. The second position is a position offset from the predetermined position by 0.3mm in the X direction. The third position is a position offset from the predetermined position by 0.1mm in the-Y direction. The fourth position is a position offset from the predetermined position by 0.3mm in the-Y direction. In the experiment, the difference between the rotation angle θm and the first angle detection value θ1s was obtained as the error of the first angle detection value θ1s, and the difference between the rotation angle θm and the detection value θs was obtained as the error of the detection value θs. The error of the first angle detection value θ1s corresponds to the error of the detection value θs in the case where only the first magnetic sensor 10 is used.

Fig. 9 is a characteristic diagram showing errors of the first angle detection value θ1s and the detection value θs in a first state in which the rotation center of the magnetic field generator 5 is deviated to the first position. Fig. 10 is a characteristic diagram showing errors of the first angle detection value θ1s and the detection value θs in the second state in which the rotation center of the magnetic field generator 5 is deviated to the second position. Fig. 11 is a characteristic diagram showing errors of the first angle detection value θ1s and the detection value θs in a third state in which the rotation center of the magnetic field generator 5 is deviated to the third position. Fig. 12 is a characteristic diagram showing errors of the first angle detection value θ1s and the detection value θs in a fourth state in which the rotation center of the magnetic field generator 5 is deviated to the fourth position.

In fig. 9 to 12, the horizontal axis represents the rotation angle θm, and the vertical axis represents the error. In fig. 9 to 12, a plurality of points connected by a broken line represent errors in the first angle detection value θ1s, and a plurality of points connected by a solid line represent errors in the detection value θs. As is clear from fig. 9 to 12, according to the present embodiment, the error of the detection value θs due to the positional shift between the magnetic field generator 5 and the first and second magnetic sensors 10 and 20 is smaller than that in the case where only the first magnetic sensor 10 is used.

The effects of the present embodiment have been described so far by taking the case where the magnetic field generator 5 is statically deviated in a predetermined direction as an example. However, the above description is also applicable to the case where the magnetic field generator 5 periodically fluctuates in the direction orthogonal to the rotation axis C.

Modification example

Next, first and second modifications of the angle sensor device 1 of the present embodiment will be described. First, a first modification of the angle sensor device 1 will be described with reference to fig. 13. In the first modification, the angle sensor device 1 includes a magnetic field generator 105 instead of the magnetic field generator 5 shown in fig. 2 and 3. The magnetic field generator 105 includes three sets of N and S poles. In the magnetic field generator 105, two magnetic poles arranged so as to sandwich the rotation axis C are two magnetic poles having opposite magnetization directions, i.e., an N-pole and an S-pole, as viewed from a direction parallel to the rotation axis C.

Next, a second modification of the angle sensor device 1 will be described with reference to fig. 14. In the second modification, the angle sensor device 1 includes a magnetic field generator 205 instead of the magnetic field generator 5 shown in fig. 2 and 3. The magnetic field generator 205 includes five sets of N and S poles. In the magnetic field generator 205, two magnetic poles arranged so as to sandwich the rotation axis C are two magnetic poles having opposite magnetization directions, i.e., an N-pole and an S-pole, as viewed from a direction parallel to the rotation axis C.

Second embodiment

Next, a second embodiment of the present invention will be described. First, the point where the angle sensor device 1 of the present embodiment is different from the first embodiment will be described with reference to fig. 15. Fig. 15 is a side view showing a main part of the angle sensor device 1 of the present embodiment.

In the present embodiment, the first position P1 and the second position P2 are different positions from each other in the direction parallel to the rotation axis C. Fig. 15 shows a virtual plane PL0 intersecting the center of the magnetic field generator 5 in a direction perpendicular to the rotation axis C and parallel to the rotation axis C. The distance from the first position P1 to the virtual plane PL0 and the distance from the second position P2 to the virtual plane PL0 may be equal to each other. The first magnetic sensor 10 is mounted on the first surface 6a of the substrate 6, and the second magnetic sensor 20 is mounted on the second surface 6b of the substrate 6. Therefore, the first magnetic sensor 10 and the second magnetic sensor 20 are disposed at different positions from each other in the direction parallel to the rotation axis C.

Next, effects of the present embodiment will be described. The magnetic field generator 5 is offset from a predetermined position (designed position) in a direction parallel to the rotation axis C, whereby the relative positional relationship between the virtual plane PL0 and the first and second positions P1 and P2 changes. In the case where the virtual plane PL0 intersects the first position P1 and the second position P2 as in the first embodiment, when the magnetic field generator 5 is deviated from the predetermined position in the direction parallel to the rotation axis C, both the first and second angle detection values θ1s, θ2s deviate from the value in the state where the magnetic field generator 5 is at the predetermined position, and the detection value θs also deviates.

In contrast, in the present embodiment, the first position P1 and the second position P2 are different positions from each other in the direction parallel to the rotation axis C. Therefore, in a state where the magnetic field generator 5 is at the predetermined position, the first and second angle detection values θ1s, θ2s are each deviated from the value in a case where the virtual plane PL0 intersects the first position P1 and the second position P2. When the magnetic field generator 5 is deviated from the predetermined position in the direction parallel to the rotation axis C, one of the first and second angle detection values θ1s and θ2s is deviated more, but the other is deviated less. Thus, according to the present embodiment, the error of the detection value θs caused by the positional deviation of the magnetic field generator 5 in the direction parallel to the rotation axis C can be reduced.

In the case where the influence of the positional deviation of the magnetic field generator 5 in the direction parallel to the rotation axis C on the error of the detection value θs is significantly smaller than the influence of the positional deviation of the magnetic field generator 5 in the direction orthogonal to the rotation axis C on the error of the detection value θs, the first position P1 and the second position P2 may be set to the same position in the direction parallel to the rotation axis C as in the first embodiment.

Other structures, operations, and effects in the present embodiment are the same as those in the first embodiment.

Third embodiment

Next, a third embodiment of the present invention will be described with reference to fig. 16. Fig. 16 is a side view showing a main part of the angle sensor device 1 of the present embodiment.

The angle sensor device 1 of the present embodiment differs from the second embodiment in the following points. The angle sensor device 1 of the present embodiment includes two substrates 61 and 62 instead of the substrate 6 of the second embodiment. The substrate 61 has a first face 61a located at one end in the Z direction and a second face 61b located at one end in the-Z direction. The substrate 62 has a first face 62a at one end in the Z direction and a second face 62b at one end in the-Z direction. The substrates 61 and 62 are arranged so as to sandwich the magnetic field generator 5 and the shaft 101 when viewed from a direction parallel to the rotation axis. The substrates 61 and 62 may be fixed to each other or to another substrate not shown.

The first magnetic sensor 10 is mounted on the first surface 61a of the substrate 61. The second magnetic sensor 20 is mounted on the first surface 62a of the substrate 62. The substrates 61 and 62 are disposed at different positions from each other in a direction parallel to the rotation axis C. Therefore, the first magnetic sensor 10 and the second magnetic sensor 20 are also disposed at different positions from each other in the direction parallel to the rotation axis C.

Other structures, operations, and effects of the present embodiment are the same as those of the second embodiment.

Fourth embodiment

Next, a fourth embodiment of the present invention will be described with reference to fig. 17. Fig. 17 is a plan view showing a main part of the angle sensor device according to the present embodiment. The angle detection device 100 according to the present embodiment is different from the first embodiment in the following description. The angle detection device 100 of the present embodiment includes an angle sensor device 201 instead of the angle sensor device 1 of the first embodiment.

The angle sensor device 201 includes the magnetic field generator 5, the first magnetic sensor 10, the second magnetic sensor 20, and the substrate 6 described in the first embodiment. The angle sensor device 201 further includes a holder 207. In the present embodiment, the holder 207 houses the first and second magnetic sensors 10, 20, but does not house the magnetic field generator 5.

Other structures of the angle sensor device 201 may be the same as those of any of the first to third embodiments. The other structure, operation, and effects of this embodiment are the same as those of any of the first to third embodiments.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, the magnetic field generator 5 is not limited to 1, 3, or 5 sets of N and S poles, and may include 7 or more odd sets of N and S poles.

Based on the above description, various aspects and modifications of the present invention can be implemented. Therefore, the present invention can be implemented in a mode other than the above-described optimal mode within the scope of the appended claims.

Claims (11)

1. An angle sensor device, comprising:

a magnetic field generator configured to generate a target magnetic field and to rotate about a rotation axis; and

the first magnetic sensor and the second magnetic sensor are disposed at a first position and a second position, respectively, on the outer side of the outer peripheral surface of the magnetic field generator, with the rotation shaft interposed therebetween, when viewed from a direction parallel to the rotation shaft,

the magnetic field generator includes a plurality of magnetic poles arranged along an axial direction of the rotation shaft,

the plurality of magnetic poles include two magnetic poles which are arranged so as to sandwich the rotation axis and have magnetization directions opposite to each other as viewed from a direction parallel to the rotation axis,

the first magnetic sensor includes: a first detection circuit and a second detection circuit configured to detect the object magnetic field at the first position and output detection signals, respectively; a first arithmetic circuit configured to calculate a first angle detection value of the magnetic field generator as a detection value of a rotation angle based on detection signals of the first detection circuit and the second detection circuit, respectively,

The second magnetic sensor includes: a third detection circuit and a fourth detection circuit configured to detect the object magnetic field at the second position and output detection signals, respectively; a second arithmetic circuit configured to calculate a second angle detection value as a detection value of the rotation angle based on detection signals of the third detection circuit and the fourth detection circuit,

the first detection circuit and the third detection circuit are each configured to have sensitivity in a first direction, and are each configured to have a maximum detection signal when a first magnetic field component in a specific one direction parallel to the first direction is applied,

the second detection circuit and the fourth detection circuit are each configured to have sensitivity in a second direction, and are each configured to have a maximum detection signal when a second magnetic field component in a specific one direction parallel to the second direction is applied.

2. The angle sensor device according to claim 1, wherein,

the second position is a position rotated 180 ° about the rotation axis from the first position in the axial direction when viewed from a direction parallel to the rotation axis.

3. The angle sensor device according to claim 1, wherein,

the magnetic field generator is arranged such that, when viewed from a direction perpendicular to the rotation axis, the whole thereof intersects with an imaginary plane perpendicular to the rotation axis,

the distance from the first position to the virtual plane and the distance from the second position to the virtual plane are equal to each other.

4. The angle sensor device according to claim 1, wherein,

the first position and the second position are the same positions in a direction parallel to the rotation axis.

5. The angle sensor device according to claim 1, wherein,

the first position and the second position are positions different from each other in a direction parallel to the rotation axis.

6. The angle sensor device according to claim 1, wherein,

the magnetic field generator includes an odd number of the two poles as the plurality of poles.

7. The angle sensor device according to claim 1, wherein,

further comprises a substrate on which the first magnetic sensor and the second magnetic sensor are mounted,

the substrate has a first surface and a second surface at both ends in a direction parallel to the rotation axis,

The first magnetic sensor is mounted on the first surface,

the second magnetic sensor is mounted on the first surface or the second surface.

8. The angle sensor device according to claim 1, wherein,

the device further comprises:

a first substrate on which the first magnetic sensor is mounted;

and a second substrate on which the second magnetic sensor is mounted.

9. The angle sensor device according to claim 1, wherein,

the method further includes generating a corrected detection value based on the first angle detection value and the second angle detection value.

10. The angle sensor device according to claim 1, wherein,

the magnetic field generator, the first magnetic sensor, and the second magnetic sensor are housed in a holder.

11. An angle detection device is characterized by comprising:

the angle sensor device of claim 1; and

Fixing the shaft of the magnetic field generator.

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