JP5454204B2 - Angle sensor - Google Patents

Description

  The present invention relates to an angle sensor that detects a rotation angle of a rotation shaft.

  As a magnetic sensor for detecting an external magnetic field, a magnetoresistive effect element such as a giant magnetoresistive effect element or a magnetic tunnel effect element is used. Magnetoresistive elements have a magnetization direction that is set to a specific direction and is configured so that the magnetization state (for example, the magnetization direction and the strength of magnetization) is not affected by the displacement of the external magnetic field. A layer (pinned magnetic layer) and a magnetization free layer (free magnetic layer) whose magnetization state is displaced by a change in an external magnetic field. When an external magnetic field acts on the magnetoresistive effect element, the magnetization state of the magnetization free layer changes, and the magnetization state between the magnetization state of the magnetization fixed layer in which the magnetization state is fixed and the magnetization free layer in which the magnetization state changes The displacement difference is generated. This displacement difference in the magnetized state appears as a change in magnetoresistance of the magnetoresistive effect element. As an application example of this type of magnetoresistive effect element, for example, in Japanese Patent Application Laid-Open No. 2006-214862, a magnetic track is NS magnetized with a uniform width and strength so as to face the circumferential surface of the magnetic track. A position detection device that detects a rotation angle position of a rotating body based on a magnetic intensity signal output from a magnetoresistive element arranged is disclosed.

JP 2006-214862 A

  However, it is technically difficult to NS magnetize a magnetic track with a uniform width and strength, which causes an increase in cost.

  Therefore, an object of the present invention is to provide a highly accurate angle sensor at low cost.

  In order to solve the above-described problems, an angle sensor according to the present invention has a main surface that is inclined with respect to the axial direction of the rotating shaft, and a rotor that rotates in conjunction with rotation around the axis of the rotating shaft. A magnetic sensor that detects a magnetic field in which the magnetic field strength and the magnetic field direction periodically change due to the surface vibration of the rotor that occurs when the rotor rotates, and that outputs a detection signal including information on the rotation angle of the rotating shaft, and based on the detection signal And a signal processing circuit for calculating a rotation angle of the rotation shaft. Due to the surface vibration of the rotor accompanying the rotation of the rotating shaft, the deflection angle of the magnetic field acting on the magnetic sensor can be increased, so that the detection resolution can be improved. In addition, since the rotor is configured to be shaken when the rotating shaft rotates, the rotor shape can be reduced without reducing the angle detection resolution. Thereby, size reduction of the whole angle sensor is realizable.

  The magnetic sensor includes a magnetoresistive effect element including a magnetization fixed layer whose magnetization direction is fixed and a magnetization free layer whose magnetization direction changes under the action of a magnetic field. Adjust the magnetization direction of the magnetization pinned layer so that the two components perpendicular to the axis direction of the magnetization direction of the magnetization pinned layer are more strongly affected by the magnetic field than the one component parallel to the axis direction of the magnetization direction of the magnetization pinned layer. The magnetic sensor may be disposed at a position between the highest point and the lowest point of the surface shake of the rotor. As a result, the detection signal output from the magnetic sensor has a signal waveform having two local maximums and minimums per rotation of the rotor.

  A magnetic sensor may be arranged at a position shifted from the rotation center of the rotor so that the detection signal becomes a signal that outputs two asymmetric signal waveforms per rotation of the rotation axis, and the magnetization direction axis of the magnetization fixed layer It may be adjusted so that the value of one component parallel to the core direction is greater than zero, or the cross-sectional shape of the rotor cut along a plane parallel to the axial direction is point-symmetric with respect to the rotation center of the rotor You may adjust to shapes other than. Thereby, angle detection accuracy can be improved.

  Adjust the magnetization direction of the magnetization pinned layer so that the two components perpendicular to the axis direction of the magnetization direction of the magnetization pinned layer are more strongly affected by the magnetic field than the one component parallel to the axis direction of the magnetization direction of the magnetization pinned layer. The magnetic sensor may be arranged at a position higher than the highest point of the surface shake of the rotor or a position lower than the lowest point of the face shake of the rotor. Thereby, the detection signal output from the magnetic sensor has a signal waveform having one maximum and one minimum for each rotation of the rotor.

  The magnetization direction of the magnetization fixed layer is adjusted so that one component parallel to the axis direction of the magnetization direction of the magnetization fixed layer is more strongly affected by the magnetic field than the two components orthogonal to the axis direction of the magnetization direction of the magnetization fixed layer. May be. Thereby, the detection signal output from the magnetic sensor has a signal waveform having one maximum and one minimum for each rotation of the rotor.

  According to the present invention, a highly accurate angle sensor can be provided at low cost.

It is a schematic block diagram of the angle sensor concerning this embodiment. It is a schematic block diagram of the angle sensor concerning this embodiment. It is sectional drawing of the magnetoresistive effect element concerning this embodiment. It is explanatory drawing which shows each component of the magnetization direction of a magnetization fixed layer. It is a graph which shows the change of a detection signal. It is a graph which shows the change of a detection signal. It is a graph which shows the change of a detection signal. It is a graph which shows the change of a detection signal. It is a graph which shows the change of a detection signal. It is a block diagram of the rotor concerning this embodiment. It is a schematic block diagram of the angle sensor concerning this embodiment. It is a block diagram of the rotor concerning this embodiment. It is a schematic block diagram of the angle sensor concerning this embodiment. It is a schematic block diagram of the angle sensor concerning this embodiment. It is a schematic block diagram of the angle sensor concerning this embodiment. It is a schematic block diagram of the angle sensor concerning this embodiment. It is a block diagram of the magnetic sensor concerning this embodiment. It is explanatory drawing of the magnetization direction of the magnetization fixed layer concerning this embodiment. It is a block diagram of the magnetic sensor concerning this embodiment. It is explanatory drawing of the magnetization direction of the magnetization fixed layer concerning this embodiment. It is a block diagram of the magnetic sensor concerning this embodiment. It is explanatory drawing of the magnetization direction of the magnetization fixed layer concerning this embodiment.

  Embodiments according to the present invention will be described below with reference to the drawings. About the same member, the same code | symbol shall be attached | subjected and the overlapping description is abbreviate | omitted.

  FIG. 1 shows a schematic configuration of an angle sensor 10 according to the present embodiment. The angle sensor 10 is an angle detection device for detecting a rotation angle (0 deg to 360 deg) within one rotation of the rotary shaft 21 from a predetermined reference position. Examples of the rotating shaft 21 include a steering shaft, but are not limited thereto. The angle sensor 10 is output from the rotor 22 that rotates in conjunction with the rotation of the rotation shaft 21 around the axis, the magnetic sensor 30 that outputs a detection signal including information on the rotation angle of the rotation shaft 21, and the magnetic sensor 30. And a signal processing circuit 40 for calculating the rotation angle of the rotating shaft 21 based on the detected signal. The rotor 22 is a rotating member made of a ferromagnetic material (for example, iron, cobalt, nickel, etc.), and its planar shape (cross-sectional shape cut by a plane perpendicular to the thickness direction of the rotor 22) is, for example, a circle or an ellipse. However, it is not limited to a specific shape, and various shapes can be adopted. The rotor 22 has a first main surface 22 </ b> A and a second main surface 22 </ b> B that is the back surface thereof, and these main surfaces 22 </ b> A and 22 </ b> B are inclined with respect to the axial direction of the rotating shaft 21. The rotor 22 is attached to the rotating shaft 21. The rotor 22 may be fixed to the rotating shaft 21 or may be serrated. Assuming that the axis direction of the rotating shaft 21 is the Z direction, the rotor 22 rotates while being faced in the Z-axis direction as the rotating shaft 21 rotates. In FIG. 1, Z 0 indicates the Z coordinate of the rotation center of the rotor 22, Z 1 indicates the Z coordinate of the highest point of the surface shake of the rotor 22, and Z 2 indicates the Z coordinate of the lowest point of the surface shake of the rotor 22.

  The magnetic sensor 30 includes a magnet 32 that functions as a magnetic field generating unit for generating an external magnetic field 50, and an external magnetic field 50 in which the magnetic field strength and the magnetic field direction periodically change with the surface vibration of the rotor 22 that occurs when the rotor 22 rotates. And a magnetoresistive effect element 31 that detects the change as a voltage change. As a mounting form of the magnetic sensor 30, for example, as shown in FIG. 17, the surface of the printed wiring board 33 so that the line connecting the center point of the magnet 32 and the center point of the magnetoresistive effect element 31 is parallel to the X direction. Alternatively, the magnetoresistive effect element 31 may be disposed, and the magnet 32 may be disposed on the back surface of the printed wiring board 33. In the case of such an arrangement, as shown in FIG. 18, the magnetization direction 63A of the magnetization fixed layer of the magnetoresistive effect element 31 faces an arbitrary direction in the YZ plane. Further, for example, as shown in FIG. 19, the magnetoresistive effect element is formed on the back surface of the printed circuit board 33 so that the line connecting the center point of the magnetoresistive effect element 31 and the center point of the printed circuit board 33 is parallel to the Z direction. 31 may be arranged. In the case of such an arrangement, as shown in FIG. 20, the magnetization direction 63A of the magnetization fixed layer of the magnetoresistive effect element 31 faces an arbitrary direction in the XY plane. Further, for example, as shown in FIG. 21, the magnetoresistive effect element is formed on the surface of the printed wiring board 33 so that a line connecting the center point of the magnetoresistive effect element 31 and the center point of the printed wiring board 33 is parallel to the Y direction. 31 may be disposed (note that the printed wiring board 33 is not shown because it is disposed on the back surface of the magnetoresistive effect element 31). In the case of such an arrangement, as shown in FIG. 22, the magnetization direction 63A of the magnetization fixed layer of the magnetoresistive effect element 31 faces an arbitrary direction in the ZX plane. Further, in order to efficiently collect the external magnetic field 50 generated from the magnet 32, it is preferable to arrange yokes (not shown) on both poles of the magnet 32. As the magnetoresistive effect element 31, a known magnetoresistive effect element such as a giant magnetoresistive (GMR) type, a tunnel magnetoresistive (TMR) type, a ballistic magnetoresistive (BMR) type, an anisotropic magnetoresistive (AMR) type or the like is used. be able to.

  FIG. 3 shows a cross-sectional structure of the magnetoresistive effect element 31. The magnetoresistive element 31 has a structure in which a base layer 61, an antiferromagnetic layer 62, a magnetization fixed layer 63, a nonmagnetic conductive layer 64, a magnetization free layer 65, and a protective layer 66 are laminated. The magnetization direction 63 </ b> A of the magnetization fixed layer 63 is hardly affected by the external magnetic field 50 because it is strongly magnetically coupled with the magnetization direction 62 </ b> A of the antiferromagnetic layer 62. On the other hand, the magnetization direction 65 </ b> A of the magnetization free layer 65 changes so as to follow the magnetic field direction of the external magnetic field 50. It is known that the magnetoresistance of the magnetoresistive effect element 31 changes depending on the magnetic field strength of the external magnetic field 50 detected by the magnetoresistive effect element 31 and the direction of the magnetic field. If the magnetic field strength of the external magnetic field 50 is constant, the magnetoresistance of the magnetoresistive element 31 is an angular difference (ξ) between the magnetization direction 63A of the magnetization fixed layer 63 and the magnetization direction 65A of the magnetization free layer 65. It changes depending on. More specifically, the magnetoresistance of the magnetoresistive effect element 31 has a characteristic that changes in proportion to (1-cosξ), and the magnetization direction 63A of the magnetization fixed layer 63 and the magnetization direction 65A of the magnetization free layer 65 Are the same and parallel to each other, and the magnetoresistance is minimized. When the magnetization direction 63A of the magnetization fixed layer 63 and the magnetization direction 65A of the magnetization free layer 65 are opposite and parallel, the magnetoresistance is maximized. As described above, since the rotor 22 is attached to the rotating shaft 21 so that surface vibration occurs when the rotating shaft 21 rotates, the distance between the edge of the rotor 22 and the magnetic sensor 30, and the magnet 32 to the rotor 22. The direction of the external magnetic field 50 toward the edge of the magnetic field periodically changes, and accordingly, the magnetic field strength and magnetic field direction of the external magnetic field 50 acting on the magnetoresistive effect element 31 change periodically. A sense current is supplied from the printed wiring board 33 to the magnetoresistive effect element 31, and a change in magnetoresistance of the magnetoresistive effect element 31 is detected as a change in output voltage. The output voltage of the magnetoresistive effect element 31 is signal-processed as a detection signal including information on the rotation angle of the rotating shaft 21. As the rotary shaft 21 rotates, the rotor 22 rotates while being shaken in the Z-axis direction, so that the amount of change in the detection signal per unit angle change increases. For this reason, even if the diameter of the rotor 22 is shortened, a practically sufficient angle detection resolution can be obtained, and the angle sensor 10 as a whole can be downsized and the rotor 22 can be rotated at high speed.

  For convenience of explanation, FIG. 1 shows one magnetoresistive element 31. However, since there may be a plurality of rotation angles of the rotary shaft 21 corresponding to one value of the detection signal, as shown in FIG. It is preferable that two magnetic sensors 30 are arranged at an angle θ with respect to the center of the shaft 21 and the rotation angle of the rotation shaft 21 is obtained based on two detection signals having a predetermined phase difference (for example, 90 deg). The detection signal output from the magnetoresistive effect element 31 is affected by various factors such as (1) the magnetization direction 63A of the magnetization fixed layer 63, (2) the position of the magnetic sensor 30, and (3) the shape of the rotor 22. Thus, one rotation or a two-cycle periodic signal is generated per rotation of the rotating shaft 21. When the detection signal becomes a periodic signal having one waveform per one rotation of the rotating shaft 21, two magnetic sensors 30 may be arranged at θ = 90 deg in FIG. When the detection signal is a periodic signal having two waveforms per rotation of the rotating shaft 21, two magnetic sensors 30 may be arranged at θ = 45 deg in FIG. The signal processing circuit 40 holds a data table (or function) indicating the correspondence between the detection signal output from each magnetic sensor 30 and the rotation angle of the rotary shaft 21 in a memory (not shown), respectively. The rotation angle of the rotary shaft 21 is obtained by comparing the detection signal output from the magnetic sensor 30 and the data table (or function).

  Next, the relationship between the magnetization direction 63 </ b> A of the magnetization fixed layer 63 and the detection signal of the magnetic sensor 30 will be described with reference to FIGS. 4 to 9. Px, Py, and Pz shown in FIG. 4 indicate an X component, a Y component, and a Z component of the magnetization direction 63A of the magnetization fixed layer 63, respectively. Since Pz is parallel to the axial direction of the rotating shaft 21, the magnetoresistive component caused by Pz of the magnetoresistive effect element 31 has one maximum and one minimum for each rotation of the rotor 22. On the other hand, since Px and Py are orthogonal to the axial direction of the rotating shaft 21, the magnetoresistive component caused by Px and Py of the magnetoresistive effect element 31 has two maximums and minimums per rotation of the rotor 22.

  The waveform of the detection signal output from the magnetoresistive effect element 31 can be divided into the following three cases.

  First, as a first case, two components (Px, Py) perpendicular to the Z direction of the magnetization direction 63A of the magnetization fixed layer 63 are more than one component (Pz) parallel to the Z direction of the magnetization direction 63A of the magnetization fixed layer 63. Also, the magnetization direction 63A of the magnetization fixed layer 63 is adjusted so as to be strongly influenced by the external magnetic field 50, and the Z coordinate of the magnetic sensor 30 is the highest point (Z1) and the lowest point (Z2) of the surface shake of the rotor 22. ), The detection signal output from the magnetic sensor 30 has a signal waveform having two maximums and two minimums per rotation of the rotor 22.

  Next, as a second case, two components (Px, Py) orthogonal to the Z direction of the magnetization direction 63A of the magnetization fixed layer 63 are one component (Pz) parallel to the Z direction of the magnetization direction 63A of the magnetization fixed layer 63. The magnetization direction 63A of the magnetization fixed layer 63 is adjusted so as to be more strongly affected by the external magnetic field 50, and the Z coordinate of the magnetic sensor 30 is higher than the highest point (Z1) of the surface shake of the rotor 22 or When the position is lower than the lowest point (Z2) of the surface shake of the rotor 22, the detection signal output from the magnetic sensor 30 has a signal waveform having one maximum and one minimum for each rotation of the rotor 22.

  Finally, as a third case, one component (Pz) parallel to the Z direction of the magnetization direction 63A of the magnetization fixed layer 63 is two components (Px, Py) orthogonal to the Z direction of the magnetization direction 63A of the magnetization fixed layer 63. When the magnetization direction 63A of the magnetization fixed layer 63 is adjusted so as to be more strongly affected by the external magnetic field 50, the detection signal output from the magnetic sensor 30 has the maximum and minimum values per rotation of the rotor 22. Each has one signal waveform.

  For example, when the magnetic resistance element 31 is present in a plane using the circular rotor 22 and including the rotation center and having the rotation axis 21 as a normal vector, the magnetoresistance component caused by Pz of the magnetoresistance effect element 31 is Assuming that sinφ is a magnetoresistive component due to Px and Py of the magnetoresistive effect element 31 and sin2φ is a and b are constants, the detection signal output from the magnetoresistive effect element 31 is described as b × sinφ + a × sin2φ. can do. FIG. 5 is a graph showing changes in the detection signal per rotation of the rotor 22 when a = 1 and b = 1 and the Z coordinate of the magnetic sensor 30 is Z0. In this case, the detection signal has a signal waveform having two local maxima and minima across the voltage 0. FIG. 6 is a graph showing changes in the detection signal per rotation of the rotor 22 when a = 0.5, b = 1, and when the Z coordinate of the magnetic sensor 30 is Z0. In this case, the detection signal has a signal waveform having one maximum and one minimum across voltage 0 and an inflection point at voltage 0. FIG. 7 is a graph showing changes in the detection signal per rotation of the rotor 22 when a = 0.25, b = 1, and when the Z coordinate of the magnetic sensor 30 is Z0. In this case, the detection signal has a signal waveform having one maximum and one minimum across the voltage 0. Therefore, it can be seen that the detection signal at one rotation of the rotor 22 changes due to the influence of the Px, Py, and Pz components of the magnetoresistive element 31. That is, in practice, since the position of the magnetoresistive element 31 is also affected, the detection signal is not symmetrical as a result.

  When the detection signal output from the magnetic sensor 30 has a signal waveform having two maximum and minimum values per rotation of the rotor 22, two asymmetric signal waveforms are output as detection signals per rotation of the rotor 22. As described above, it is preferable to adjust the position (Z coordinate) of the magnetic sensor 30, the value of one component (Pz) parallel to the Z direction of the magnetization direction 63A of the magnetization fixed layer 63, or the shape of the rotor 22. Only one of these three factors may be adjusted, or two or three factors may be adjusted. When these factors influence each other, the symmetry of the detection signal with respect to the voltage 0 is lost, and two asymmetric signal waveforms are obtained for each rotation of the rotor 22. For example, one of the two magnetic sensors 30 has a detection signal f (ψ), and the other detection signal is f (ψ + α). Here, ψ represents the rotation angle (0 to 360 deg) of the rotating shaft 21, and α represents the phase difference between the two detection signals. In order to prevent f (ψ + α) = f (β + α) when f (ψ) = f (β) when an arbitrary rotation angle of the rotation shaft 21 is β, two rotations of the rotor 22 are required. It is preferable to use a detection signal having two asymmetric signal waveforms. When the rotation angle of the rotating shaft 21 is detected by giving a predetermined phase difference between the two detection signals output from the two magnetic sensors 30, detection signals having two asymmetric signal waveforms for one rotation of the rotor 22 are obtained. By using it, highly accurate angle detection performance can be obtained. The above description is also applied to the case where two or more waveform signals are output per rotation of the rotating shaft 21. However, in the case where it is not possible to cope with the above description, angle detection can be performed by adding a new angle sensor 10 and increasing the number of combinations. For example, the detection signals of the n number of angle sensors 10 are f (φ), f (φ + α1), f (φ + α2)..., F (φ + αn). The detection signals of the n angle sensors 10 at an arbitrary angle β are f (β), f (β + α1), f (β + α2)..., F (β + αn). If f (φ) = f (β), f (φ + α1) = f (β + α1),... F (φ + αm) ≠ f (β + αm),... F (φ + αn) If at least one different detection signal value exists, such as = f (β + αn), angle detection is possible.

  As an example of f (ψ + α) = f (β + α) when f (ψ) = f (β), for example, the detection signals shown in FIGS. 8 and 9 can be taken up. FIG. 8 is a graph showing changes in the detection signal per rotation of the rotor 22 when a = 1 and b = 0 and the Z coordinate of the magnetic sensor 30 is Z0. FIG. 9 is a graph of detection signals having the same voltage value over a certain period. The detection signals shown in FIGS. 8 and 9 are preferably not suitable for detecting the rotation angle of the rotary shaft 21 by giving a predetermined phase difference between the two detection signals output from the two magnetic sensors 30. Absent. When f (ψ) has two local maxima and minima for each rotation of the rotating shaft 21, it is preferable that the signal waveform does not change the sign of curvature. This is because if the sign of the curvature changes, there are at most two values of f (ψ) corresponding to the same rotation angle, and the angle cannot be detected.

  In order for two asymmetric signal waveforms to be output as detection signals for each rotation of the rotor 22, the position (Z coordinate) of the magnetic sensor 30 is set to a predetermined distance (ΔZ) in the Z direction from the rotation center (Z 0) of the rotor 22. The magnetization direction 63A is adjusted so that the value of one component (Pz) parallel to the Z direction of the magnetization direction 63A of the magnetization fixed layer 63 is greater than zero. Is preferred. As a result, the detection signal is shifted to a position offset with respect to the voltage 0, so that two asymmetric signal waveforms are obtained for each rotation of the rotor 22. However, it is assumed that the Z coordinate of the magnetic sensor 30 is between the highest point (Z1) and the lowest point (Z2) of the surface shake of the rotor 22.

  In order to output two asymmetric signal waveforms as one detection signal for one rotation of the rotor 22, the shape of the rotor 22 and its mounting structure may be devised as shown in FIGS.

  10 and 11, the main surfaces 22 </ b> A and 22 </ b> B of the rotor 22 are deviated from the center point P of the circular rotor 22 with a constant thickness so that the main surfaces 22 </ b> A and 22 </ b> B are inclined with respect to the axial direction of the rotating shaft 21. The example which attaches the rotating shaft 21 to the position Q is shown. In this example, the Z coordinate of the magnetic sensor 30 may be between the highest point (Z1) and the lowest point (Z2) of the surface shake of the rotor 22. Since the attachment position of the rotor 22 to the rotating shaft 21 is eccentric, the detection signal output from the magnetic sensor 30 has two asymmetric signal waveforms for one rotation of the rotor 22.

  12 and 13, the rotation shaft 21 is arranged at the center point R of the elliptical rotor 22 having a constant thickness so that the main surfaces 22A and 22B of the rotor 22 are inclined with respect to the axial direction of the rotation shaft 21. An example of mounting is shown. In this example, the Z coordinate of the magnetic sensor 30 may be between the highest point (Z1) and the lowest point (Z2) of the surface shake of the rotor 22. Since the planar shape of the rotor 22 is an ellipse, the detection signal output from the magnetic sensor 30 has two asymmetric signal waveforms per rotation of the rotor 22.

  As shown in FIGS. 14 to 16, the shape of the cross section obtained by cutting the rotor 22 along a plane parallel to the axial direction of the rotation shaft 21 may be a shape other than the shape that is point-symmetric with respect to the rotation center of the rotor 22. By processing the cross-sectional shape of the rotor 22 into such a shape, the angle of the external magnetic field 50 acting on the magnetic sensor 30 changes unevenly. Therefore, the detection signal output from the magnetic sensor 30 There are two asymmetric signal waveforms per rotation. For example, the cross-sectional shape of the rotor 22 shown in FIG. 14 is processed so as to be line symmetric, and the cross-sectional shape of the rotor 22 shown in FIG. 15 is processed so that the edges on both sides are different. The cross-sectional shape of the rotor 22 shown in FIG. 16 is processed so that the thickness of the rotor 22 changes.

  When the detection signal output from the magnetic sensor 30 has a signal waveform having one maximum and one minimum per rotation of the rotor 22, adjustment for making the detection signal asymmetric is unnecessary.

  According to the angle sensor 10 according to the present embodiment, the deflection angle of the external magnetic field 50 acting on the magnetic sensor 30 can be increased by the surface shake of the rotor 22 accompanying the rotation of the rotating shaft 21, so that the detection resolution can be improved. Further, if the detection signal output from the magnetic sensor 30 has a signal waveform having two maximums and minimums per rotation of the rotor 22, it is assumed that an error has occurred in the position of the magnetic sensor 30 and the shape of the rotor 22. However, since the detection signal only needs to be asymmetric, sufficient detection accuracy can be obtained with low processing accuracy. Further, since the two magnetic sensors 30 may be arranged at an angle of 45 degrees with respect to the rotation shaft 21, the angle sensor 10 can be reduced in size. Further, the angle sensor 10 can be further downsized by downsizing the rotor 22.

  In the present embodiment, when the magnetoresistive effect element 31 is used, the longitudinal direction of the magnetization free layer 65 is a direction orthogonal to the rotation center direction and a direction facing the in-plane direction including the rotation center. preferable. Since the longitudinal direction of the magnetization free layer 65 is perpendicular to the rotation center direction and faces the in-plane direction including the rotation center, the magnetization free layer 65 is not reversed in the longitudinal direction and there is no hysteresis. Improvement of detection accuracy can be expected.

  The angle sensor according to the present invention can be used for detecting the rotation angle of various rotating shafts such as a steering shaft and a torque detector using a rotation angle difference.

DESCRIPTION OF SYMBOLS 10 ... Angle sensor 21 ... Rotating shaft 22 ... Rotor 22A, 22B ... Main surface 30 ... Magnetic sensor 31 ... Magnetoresistive element 32 ... Magnet 33 ... Printed wiring board 40 ... Signal processing circuit 50 ... External magnetic field 61 ... Underlayer 62 ... Antiferromagnetic layer 63 ... magnetization fixed layer 64 ... nonmagnetic conductive layer 65 ... magnetization free layer 66 ... protective layer

Claims (7)

A rotor that has a main surface that is inclined with respect to the axial direction of the rotary shaft, and rotates in conjunction with the rotation of the rotary shaft around the axis;
A magnetic sensor that detects a magnetic field in which the magnetic field strength and the magnetic field direction periodically change in accordance with the surface vibration of the rotor that occurs when the rotor rotates, and outputs a detection signal including information on a rotation angle of the rotation shaft;
A signal processing circuit for calculating a rotation angle of the rotation shaft based on the detection signal;
Bei to give a,
The magnetic sensor includes a magnetoresistive element including a magnetization fixed layer whose magnetization direction is fixed, and a magnetization free layer whose magnetization direction is changed by the action of the magnetic field,
The magnetization fixed so that the two components perpendicular to the axial direction of the magnetization fixed layer are more strongly affected by the magnetic field than one component parallel to the axial direction of the magnetization fixed layer. The magnetization direction of the layer is adjusted,
The said magnetic sensor is an angle sensor arrange | positioned in the position between the highest point and the lowest point of the surface shake of the said rotor . The angle sensor according to claim 1 ,
One component of the position of the magnetic sensor and the magnetization direction of the magnetization fixed layer parallel to the axial direction so that the detection signal is a signal that outputs two asymmetric signal waveforms per rotation of the rotation axis. An angle sensor in which the value or the shape of the rotor is adjusted. The angle sensor according to claim 2 ,
The said magnetic sensor is an angle sensor arrange | positioned in the position shifted | deviated from the rotation center of the said rotor. The angle sensor according to claim 2 ,
An angle sensor, wherein a value of one component parallel to the axial direction of the magnetization direction of the magnetization fixed layer is greater than zero. The angle sensor according to claim 2 ,
The shape of the cross section which cut | disconnected the said rotor by the plane parallel to the said axial direction is an angle sensor other than the shape which becomes point-symmetrical about the rotation center of the said rotor.   A rotor that has a main surface that is inclined with respect to the axial direction of the rotary shaft, and rotates in conjunction with the rotation of the rotary shaft around the axis;
  A magnetic sensor that detects a magnetic field in which the magnetic field strength and the magnetic field direction periodically change in accordance with the surface vibration of the rotor that occurs when the rotor rotates, and outputs a detection signal including information on a rotation angle of the rotation shaft;
  A signal processing circuit for calculating a rotation angle of the rotation shaft based on the detection signal;
  With
  The magnetic sensor includes a magnetoresistive element including a magnetization fixed layer whose magnetization direction is fixed, and a magnetization free layer whose magnetization direction is changed by the action of the magnetic field,
  The magnetization fixed so that the two components perpendicular to the axial direction of the magnetization fixed layer are more strongly affected by the magnetic field than one component parallel to the axial direction of the magnetization fixed layer. The magnetization direction of the layer is adjusted,
  The said magnetic sensor is an angle sensor arrange | positioned in the position higher than the highest point of the surface shake of the said rotor, or the position lower than the lowest point of the face shake of the said rotor.   A rotor that has a main surface that is inclined with respect to the axial direction of the rotary shaft, and rotates in conjunction with the rotation of the rotary shaft around the axis;
  A magnetic sensor that detects a magnetic field in which the magnetic field strength and the magnetic field direction periodically change in accordance with the surface vibration of the rotor that occurs when the rotor rotates, and outputs a detection signal including information on a rotation angle of the rotation shaft;
  A signal processing circuit for calculating a rotation angle of the rotation shaft based on the detection signal;
  With
  The magnetic sensor includes a magnetoresistive element including a magnetization fixed layer whose magnetization direction is fixed, and a magnetization free layer whose magnetization direction is changed by the action of the magnetic field,
  One component of the magnetization direction of the magnetization pinned layer parallel to the axis direction is more strongly affected by the magnetic field than two components of the magnetization direction of the magnetization pinned layer perpendicular to the axis direction. An angle sensor in which the magnetization direction of the layer is adjusted.

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