JP6601458B2 - Angle sensor and angle sensor system - Google Patents

Description

  The present invention relates to an angle sensor and an angle sensor system including a state determination device.

  In recent years, an angle sensor that generates an angle detection value having a corresponding relationship with an angle to be detected has been widely used in various applications such as detection of a rotational position of a steering wheel or a power steering motor in an automobile. An example of the angle sensor is a magnetic angle sensor. In an angle sensor system in which a magnetic angle sensor is used, a magnetic field generator that generates a rotating magnetic field whose direction rotates in conjunction with the rotation or linear motion of an object is generally provided. The magnetic field generator is, for example, a magnet. The angle of the detection target in the magnetic angle sensor has a corresponding relationship with the angle formed by the direction of the rotating magnetic field at the reference position with respect to the reference direction.

  As an angle sensor, one that has a detection signal generation unit that generates a plurality of detection signals having different phases and generates an angle detection value by calculation using the plurality of detection signals is known. In the magnetic angle sensor, the detection signal generation unit includes a plurality of magnetic detection elements. Each of the plurality of magnetic detection elements is disposed between, for example, a magnetization fixed layer whose magnetization direction is fixed, a free layer whose magnetization direction changes according to the direction of the rotating magnetic field, and the magnetization fixed layer and the free layer. In addition, a spin valve magnetoresistive element (hereinafter also referred to as an MR element) having a nonmagnetic layer is included.

  In the angle sensor, when a failure due to a failure of the detection signal generation unit or the like occurs, an error exceeding the allowable range may occur in the angle detection value. For this reason, the angle sensor is required to have a function capable of detecting a failure. Hereinafter, an error occurring in the detected angle value is referred to as an angle error.

  In Patent Document 1, in a rotation angle detection device that detects a rotation angle based on two-phase signals that are 90 ° out of phase with each other, a failure of the rotation angle detection device is detected by monitoring the sum of squares of the two-phase signals. The technology to do is described. Further, Patent Document 1 discloses a rotation angle detection device that detects a rotation angle based on signals of three or more phases whose phases are evenly shifted, and monitors the total sum of signals of three or more phases to monitor the rotation angle detection device. Techniques for detecting faults are described.

  In Patent Document 2, in a rotation angle detection device that detects a rotation angle based on first and second sine wave signals having phase differences other than 90 ° and 180 °, the first and second sine wave signals and A technique for detecting a failure of the rotation angle detection device based on these phase differences is described.

JP 2012-21842 A JP-A-2015-59790

  Each of the plurality of techniques described in Patent Documents 1 and 2 performs an operation using a plurality of detection signals, and generates a determination value indicating whether or not a failure has occurred in the rotation angle detection device, This is a technique for determining that a failure has occurred in the rotation angle detection device when the determination value exceeds a predetermined range. The determination value is ideally a constant ideal value regardless of the angle of the detection target when no failure occurs in the rotation angle detection device, and is different from the ideal value when a failure occurs in the rotation angle detection device. Value.

  By the way, in the angle sensor having a function of determining whether or not the angle sensor is malfunctioning using the determination value as described above, an angle error occurs even when the angle sensor does not malfunction, The determination value may be different from the ideal value. This may occur, for example, when at least one of the center value, the amplitude, and the phase is deviated from a desired value in at least one of the plurality of detection signals.

  Further, for example, in a magnetic angle sensor, when the direction of the rotating magnetic field changes at a constant angular velocity and the angle of the detection target changes at a predetermined cycle, each waveform of the plurality of detection signals is ideally And sinusoidal curves (including sine and cosine waveforms). However, the waveform of each detection signal may be distorted from a sine curve. The cause of the distortion of the waveform of each detection signal is, for example, that the free layer of the MR element has magnetic anisotropy in the magnetization direction of the magnetization fixed layer of the MR element, or the magnetization direction of the magnetization fixed layer of the MR element rotates. It may be fluctuated by the influence of a magnetic field or the like. If the waveform of each detection signal is distorted, the determination value may be different from the ideal value even when the angle sensor has not failed.

  If the determination value becomes a value different from the ideal value even when no failure has occurred in the angle sensor, there arises a problem that the accuracy of determination as to whether or not the angle sensor has failed is reduced.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an angle sensor and an angle sensor system that can accurately determine the state of the angle sensor such as whether or not a failure has occurred. .

  The angle sensor of the present invention includes a detection signal generation unit that generates a plurality of detection signals each having a corresponding relationship with the angle of the detection target, and an angle detection value that has a corresponding relationship with the angle of the detection target based on the plurality of detection signals. The angle detection part which produces | generates, and the state determination apparatus are provided. The state determination device includes a determination value generation unit that generates a determination value used to determine whether or not the angle sensor is in a predetermined state, and whether or not the angle sensor is in a predetermined state based on the determination value. A discriminating unit for discriminating.

  The angle detection unit performs a common correction process for converting a plurality of pre-correction signals corresponding to a plurality of detection signals into a plurality of common post-correction signals used for generating an angle detection value and a determination value. A correction processing unit is included. The determination value generation unit generates a determination value based on the plurality of common corrected signals. In the common correction process, the angle error generated in the angle detection value is reduced compared to the case where the angle detection value is generated using a plurality of pre-correction signals without the common correction process, and the common correction process is performed. Compared to the case where determination values are generated using a plurality of pre-correction signals, the plurality of pre-correction signals are converted into a plurality of common post-correction signals so that the range of variation of the determination values according to the angle of the detection target is reduced It is a process to convert.

  In the angle sensor of the present invention, the predetermined state may be a state in which the angle sensor is not out of order.

  In the angle sensor of the present invention, the plurality of common corrected signals may be first and second common corrected signals. When the angle of the detection target changes at a predetermined cycle, each of the first and second common corrected signals includes an ideal component that periodically changes so as to draw an ideal sine curve. The phase difference between the ideal component of the first common corrected signal and the ideal component of the second common corrected signal is 90 °. The amplitudes of the first common corrected signal and the second common corrected signal are equal. In this case, the determination value generation unit may generate a determination value by performing an operation including obtaining the sum of the square of the first common corrected signal and the square of the second common corrected signal.

  In the angle sensor of the present invention, the angle of the detection target may be an angle formed by the direction of the rotating magnetic field at the reference position with respect to the reference direction. In this case, the detection signal generation unit may include a plurality of detection circuits that generate a plurality of detection signals. Each of the plurality of detection circuits may include at least one magnetic detection element that detects a rotating magnetic field. In this case, the at least one magnetic sensing element may include a plurality of magnetoresistive elements connected in series. Each of the plurality of magnetoresistive elements is arranged between a magnetization fixed layer whose magnetization direction is fixed, a free layer whose magnetization direction changes according to the direction of the rotating magnetic field, and between the magnetization fixed layer and the free layer You may have a nonmagnetic layer.

  In the angle sensor of the present invention, the common correction process may include a process of correcting offsets of a plurality of pre-correction signals.

  In the angle sensor of the present invention, the common correction process may include a process of normalizing the amplitudes of a plurality of pre-correction signals.

  In the angle sensor of the present invention, the plurality of pre-correction signals may be the first and second pre-correction signals, and the plurality of common post-correction signals are the first and second common post-correction signals. There may be. When the angle of the detection target changes at a predetermined cycle, each of the first and second pre-correction signals and the first and second common post-correction signals changes periodically to draw an ideal sine curve. Contains ideal ingredients. In this case, the common correction processing includes the ideal component of the first common corrected signal and the second component regardless of the phase difference between the ideal component of the first pre-correction signal and the ideal component of the second pre-correction signal. Processing may be included in which the phase difference of the ideal component of the common corrected signal is set to 90 °, and the amplitudes of the first common corrected signal and the second common corrected signal are made equal.

  Further, in the angle sensor of the present invention, when the angle of the detection target changes at a predetermined cycle, each of the plurality of detection signals includes an ideal component that periodically changes to draw an ideal sine curve, and an ideal component And an error component corresponding to the third harmonic of. In this case, the angle detection unit further includes a conversion processing unit that performs conversion processing for converting the plurality of detection signals into a plurality of pre-correction signals with reduced error components compared to each of the plurality of detection signals. Also good.

  Further, in the angle sensor of the present invention, when the detection target angle changes at a predetermined cycle, each of the plurality of pre-correction signals includes an ideal component and an ideal component that periodically change so as to draw an ideal sine curve. And an error component corresponding to the third harmonic relative to the component. In this case, the common correction process may include a process of reducing an error component included in each of the plurality of signals after common correction compared to each of the plurality of signals before correction.

  In the angle sensor of the present invention, the angle detection unit further uses a plurality of common corrected signals for calculation for generating an angle detection value, but not for generating a determination value. A non-common correction processing unit that performs non-common correction processing for conversion into the angle calculation signal and the second angle calculation signal may be included. The non-common correction process is a process for reducing an angle error generated in the angle detection value as compared with the case where the angle detection value is generated using a plurality of signals after common correction without performing the non-common correction process. Also good. In this case, the angle error reduced by the non-common correction process may include at least one of the first angle error component and the second angle error component. When the angle of the detection target changes at a predetermined cycle, the first angle error component changes at a cycle equal to the predetermined cycle, and the second angle error component has a cycle that is ½ of the predetermined cycle. Change. In this case, the angle error reduced by the non-common correction process may include a third angle error component. When the angle of the detection target changes at a predetermined cycle, the third angle error component changes at a quarter of the predetermined cycle.

  The angle sensor system of the present invention includes the angle sensor of the present invention and a physical information generating unit that generates physical information having a correspondence relationship with the angle to be detected. The detection signal generation unit detects physical information and generates a plurality of detection signals.

  In the angle sensor system of the present invention, the physical information generation unit may be a magnetic field generation unit that generates a rotating magnetic field as physical information. In this case, the angle of the detection target may be an angle formed by the direction of the rotating magnetic field at the reference position with respect to the reference direction.

  In the angle sensor system of the present invention, the physical information generating unit may change the relative position with respect to the angle sensor so that the angle of the detection target changes. In this case, the relative position of the physical information generation unit with respect to the angle sensor may change so as to rotate about the central axis. Alternatively, the relative position of the physical information generation unit with respect to the angle sensor may change linearly.

  In the angle sensor and the angle sensor system of the present invention, the angle detection value is generated and the determination value is generated by using a plurality of signals after common correction obtained by the common correction processing. Thereby, according to this invention, there exists an effect that it becomes possible to discriminate | determine the state of an angle sensor accurately.

1 is a perspective view showing a schematic configuration of an angle sensor system according to a first embodiment of the present invention. It is explanatory drawing which shows the definition of the direction and angle in the 1st Embodiment of this invention. It is a circuit diagram which shows the structure of the detection signal generation part of the angle sensor which concerns on the 1st Embodiment of this invention. It is a functional block diagram which shows the structure of the angle detection part and state determination apparatus of an angle sensor which concern on the 1st Embodiment of this invention. It is a functional block diagram which shows the structure of the common correction process part of the angle detection part in the 1st Embodiment of this invention. It is a functional block diagram which shows the structure of the non-common correction process part of the angle detection part in the 1st Embodiment of this invention. It is a perspective view which shows a part of one magnetic detection element in FIG. It is a circuit diagram which shows the structure of the detection signal generation part of the angle sensor which concerns on the 2nd Embodiment of this invention. It is a functional block diagram which shows the structure of the angle detection part and state determination apparatus of an angle sensor which concern on the 2nd Embodiment of this invention. It is a functional block diagram which shows the structure of the common correction process part of the angle detection part in the 2nd Embodiment of this invention. It is a functional block diagram which shows the structure of the non-common correction process part of the angle detection part in the 3rd Embodiment of this invention. It is a circuit diagram which shows the structure of the detection signal generation part of the angle sensor which concerns on the 4th Embodiment of this invention. It is a functional block diagram which shows the structure of the angle detection part and state determination apparatus of angle sensor which concern on the 4th Embodiment of this invention. It is explanatory drawing which shows the structure of the outline of the angle sensor system which concerns on the 5th Embodiment of this invention. It is explanatory drawing which shows the structure of the outline of the angle sensor system which concerns on the 6th Embodiment of this invention.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the schematic configuration of the angle sensor system according to the first embodiment of the present invention will be described with reference to FIG. The angle sensor system according to the present embodiment includes the angle sensor 1 according to the present embodiment and a physical information generation unit 5.

  The angle sensor 1 according to the present embodiment generates an angle detection value θs having a correspondence relationship with the angle θ of the detection target. The physical information generating unit 5 generates physical information having a correspondence relationship with the angle θ of the detection target of the angle sensor 1. The physical information generating unit 5 changes its relative position with respect to the angle sensor 1 so that the angle θ of the detection target changes. The angle sensor 1 according to the present embodiment is a magnetic angle sensor, and the physical information generating unit 5 in the present embodiment is a magnetic field generating unit that generates a rotating magnetic field MF as physical information. FIG. 1 shows a columnar magnet 6 as an example of the magnetic field generator. The magnet 6 has an N pole and an S pole that are arranged symmetrically about a virtual plane including the central axis of the cylinder.

  The angle sensor 1 according to the present embodiment detects a rotating magnetic field MF generated by a magnet 6. The relative position of the magnet 6 with respect to the angle sensor 1 changes so as to rotate about the central axis C. This is realized, for example, by rotating one of the angle sensor 1 and the magnet 6 around a predetermined central axis C in conjunction with an operating body (not shown) that performs a rotating operation. Alternatively, the magnet 6 and the angle sensor 1 may rotate in opposite directions, or the magnet 6 and the angle sensor 1 may rotate in the same direction at different angular velocities. When the relative position of the magnet 6 with respect to the angle sensor 1 changes, the direction of the rotating magnetic field MF detected by the angle sensor 1 rotates about the central axis C.

  The angle θ of the detection target is an angle formed by the direction of the rotating magnetic field MF at the reference position with respect to the reference direction. The reference position is located in a virtual plane (hereinafter referred to as a reference plane) parallel to one end face of the magnet 6. In this reference plane, the direction of the rotating magnetic field MF generated by the magnet 6 rotates around the reference position. The reference direction is located in the reference plane and intersects the reference position. In the following description, the direction of the rotating magnetic field MF at the reference position refers to the direction located in the reference plane. The angle sensor 1 is disposed so as to face the one end surface of the magnet 6. As will be described later in other embodiments, the magnetic field generator is not limited to the magnet 6 shown in FIG.

  The angle sensor 1 includes a detection signal generation unit 2 that generates a plurality of detection signals each having a corresponding relationship with the angle θ of the detection target. The detection signal generation unit 2 detects a rotating magnetic field MF as physical information and generates a plurality of detection signals. Particularly in the present embodiment, the detection signal generation unit 2 generates first to third detection signals S11, S12, and S13 as a plurality of detection signals. In this case, the detection signal generation unit 2 includes a first detection circuit 10 that generates the first detection signal S11, a second detection circuit 20 that generates the second detection signal S12, and a third detection signal S13. And a third detection circuit 30 for generating. In FIG. 1, for ease of understanding, the first to third detection circuits 10, 20, and 30 are drawn separately, but the first to third detection circuits 10, 20, and 30 are integrated. May be. In FIG. 1, the first to third detection circuits 10, 20, and 30 are stacked in a direction parallel to the central axis C, but the stacking order is not limited to the example shown in FIG. Each of the first to third detection circuits 10, 20, and 30 includes at least one magnetic detection element that detects the rotating magnetic field MF.

  Here, with reference to FIG. 1 and FIG. 2, the definition of the direction and angle in this Embodiment is demonstrated. First, the direction parallel to the central axis C shown in FIG. 1 and from the bottom to the top in FIG. In FIG. 2, the Z direction is represented as a direction from the back to the front in FIG. Next, two directions perpendicular to the Z direction and orthogonal to each other are defined as an X direction and a Y direction. In FIG. 2, the X direction is represented as a direction toward the right side, and the Y direction is represented as a direction toward the upper side. In addition, a direction opposite to the X direction is defined as -X direction, and a direction opposite to the Y direction is defined as -Y direction.

  The reference position PR is a position where the angle sensor 1 detects the rotating magnetic field MF. The reference direction DR is the X direction. As described above, the angle θ of the detection target is an angle formed by the direction DM of the rotating magnetic field MF at the reference position PR with respect to the reference direction DR. The direction DM of the rotating magnetic field MF is assumed to rotate counterclockwise in FIG. The angle θ is represented by a positive value when viewed counterclockwise from the reference direction DR, and is represented by a negative value when viewed clockwise from the reference direction DR.

  Next, the configuration of the detection signal generation unit 2 will be described in detail with reference to FIG. FIG. 3 is a circuit diagram showing a configuration of the detection signal generation unit 2. As described above, the detection signal generation unit 2 includes the first detection circuit 10, the second detection circuit 20, and the third detection circuit 30. The detection signal generation unit 2 further includes a power supply port V and a ground port G. A power supply voltage of a predetermined magnitude such as 5 V is applied between the power supply port V and the ground port G.

  When the direction DM of the rotating magnetic field MF rotates with a predetermined period T, the angle θ of the detection target changes with the predetermined period T. In this case, all of the first to third detection signals S11, S12, and S13 periodically change with a signal period equal to the predetermined period T. The first to third detection signals S11, S12, and S13 have different phases.

  The first detection circuit 10 has a pair of magnetic detection elements R11 and R12 connected in series and an output port E10. One end of the magnetic detection element R11 is connected to the power supply port V. The other end of the magnetic detection element R11 is connected to one end of the magnetic detection element R12 and the output port E10. The other end of the magnetic detection element R12 is connected to the ground port G. The output port E10 outputs a first detection signal S11 corresponding to the potential at the connection point of the magnetic detection elements R11 and R12.

  The second detection circuit 20 has a pair of magnetic detection elements R21 and R22 connected in series and an output port E20. One end of the magnetic detection element R21 is connected to the power supply port V. The other end of the magnetic detection element R21 is connected to one end of the magnetic detection element R22 and the output port E20. The other end of the magnetic detection element R22 is connected to the ground port G. The output port E20 outputs a second detection signal S12 corresponding to the potential at the connection point of the magnetic detection elements R21 and R22.

  The third detection circuit 30 has a pair of magnetic detection elements R31 and R32 connected in series, and an output port E30. One end of the magnetic detection element R31 is connected to the power supply port V. The other end of the magnetic detection element R31 is connected to one end of the magnetic detection element R32 and the output port E30. The other end of the magnetic detection element R32 is connected to the ground port G. The output port E30 outputs a third detection signal S13 corresponding to the potential at the connection point of the magnetic detection elements R31 and R32.

  In the present embodiment, each of the magnetic detection elements R11, R12, R21, R22, R31, and R32 includes a plurality of magnetoresistive elements (MR elements) connected in series. Each of the plurality of MR elements is, for example, a spin valve type MR element. This spin-valve MR element includes a magnetization fixed layer whose magnetization direction is fixed, a free layer that is a magnetic layer whose magnetization direction changes according to the direction DM of the rotating magnetic field MF, and a magnetization fixed layer and a free layer. And a nonmagnetic layer disposed therebetween. The spin valve MR element may be a TMR element or a GMR element. In the TMR element, the nonmagnetic layer is a tunnel barrier layer. In the GMR element, the nonmagnetic layer is a nonmagnetic conductive layer. In a spin-valve MR element, the resistance value changes according to 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 this angle is 0 °. When the angle is 180 °, the resistance value becomes the maximum value. In FIG. 3, an arrow drawn so as to overlap with the magnetic detection element represents the direction of magnetization of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element.

  In the first detection circuit 10, the magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R11 is a direction rotated by 60 ° counterclockwise from the X direction. Hereinafter, this direction is referred to as a first direction D1. The magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R12 is opposite to the first direction D1. In the first detection circuit 10, the potential at the connection point of the magnetic detection elements R11 and R12 changes according to the intensity of the component in the first direction D1 of the rotating magnetic field MF. Accordingly, the first detection circuit 10 detects the intensity of the component in the first direction D1 of the rotating magnetic field MF, and outputs a signal representing the intensity as the first detection signal S11. The intensity of the component in the first direction D1 of the rotating magnetic field MF has a corresponding relationship with the angle θ of the detection target.

  In the second detection circuit 20, the magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R21 is the X direction. Hereinafter, this direction is referred to as a second direction D2. The magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R22 is the direction opposite to the second direction D2, that is, the −X direction. In the second detection circuit 20, the potential at the connection point of the magnetic detection elements R21 and R22 changes according to the intensity of the component in the second direction D2 of the rotating magnetic field MF. Accordingly, the second detection circuit 20 detects the intensity of the component in the second direction D2 of the rotating magnetic field MF, and outputs a signal representing the intensity as the second detection signal S12. The intensity of the component in the second direction D2 of the rotating magnetic field MF has a corresponding relationship with the angle θ of the detection target.

  In the third detection circuit 30, the magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R31 is a direction rotated by 60 ° clockwise from the X direction. Hereinafter, this direction is referred to as a third direction D3. The magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R32 is opposite to the third direction D3. In the third detection circuit 30, the potential at the connection point of the magnetic detection elements R31 and R32 changes according to the intensity of the component in the third direction D3 of the rotating magnetic field MF. Therefore, the third detection circuit 30 detects the intensity of the component in the third direction D3 of the rotating magnetic field MF, and outputs a signal representing the intensity as the third detection signal S13. The intensity of the component in the third direction D3 of the rotating magnetic field MF has a corresponding relationship with the angle θ of the detection target.

  Note that the magnetization direction of the magnetization fixed layer in the plurality of MR elements in the detection circuits 10, 20, and 30 may be slightly deviated from the above-mentioned direction from the viewpoint of the accuracy of manufacturing the MR element.

  Here, an example of the configuration of the magnetic detection element will be described with reference to FIG. FIG. 7 is a perspective view showing a part of one magnetic detection element in the detection signal generation unit 2 shown in FIG. In this example, one magnetic detection element has a plurality of lower electrodes 62, a plurality of MR elements 50, and a plurality of upper electrodes 63. The plurality of lower electrodes 62 are arranged on a substrate (not shown). Each lower electrode 62 has an elongated shape. A gap is formed between two lower electrodes 62 adjacent to each other in the longitudinal direction of the lower electrode 62. As shown in FIG. 7, MR elements 50 are arranged on the upper surface of the lower electrode 62 in the vicinity of both ends in the longitudinal direction. The MR element 50 includes a free layer 51, a nonmagnetic layer 52, a magnetization fixed layer 53, and an antiferromagnetic layer 54, which are stacked in order from the lower electrode 62 side. The free layer 51 is electrically connected to the lower electrode 62. The antiferromagnetic layer 54 is made of an antiferromagnetic material and causes exchange coupling with the magnetization fixed layer 53 to fix the magnetization direction of the magnetization fixed layer 53. The plurality of upper electrodes 63 are disposed on the plurality of MR elements 50. Each upper electrode 63 has an elongated shape, and is disposed on two lower electrodes 62 adjacent to each other in the longitudinal direction of the lower electrode 62 to electrically connect the antiferromagnetic layers 54 of the two adjacent MR elements 50. To do. With such a configuration, the magnetic detection element shown in FIG. 7 includes a plurality of MR elements 50 connected in series by a plurality of lower electrodes 62 and a plurality of upper electrodes 63. The arrangement of the layers 51 to 54 in the MR element 50 may be upside down from the arrangement shown in FIG.

  As described above, when the detection target angle θ changes with the predetermined period T, the first to third detection signals S11, S12, and S13 are all periodically with a signal period equal to the predetermined period T. Change. When the angle θ of the detection object changes with a predetermined period T, each of the detection signals S11, S12, and S13 draws an ideal sine curve (including a sine waveform and a cosine waveform). It includes an ideal component that changes periodically and an error component other than the ideal component. The detection signals S11, S12, and S13 are such that the phases of their ideal components are different from each other and have a predetermined phase relationship. In the present embodiment, in particular, in the detection signals S11 and S12, the phases of their ideal components differ from each other by 60 °. In the detection signals S12 and S13, the phases of these ideal components differ from each other by 60 °. In the detection signals S11 and S13, the phases of these ideal components differ from each other by 120 °.

  Causes of error components of the detection signals S11, S12, and S13 are that the free layer 51 of the MR element 50 has magnetic anisotropy in the magnetization direction of the magnetization fixed layer 53 of the MR element 50, and the magnetization of the MR element 50. For example, the magnetization direction of the fixed layer 53 may vary due to the influence of the rotating magnetic field MF or the like. The error component due to these causes is mainly an error component corresponding to the third harmonic with respect to the ideal component.

  Next, with reference to FIG. 4, portions other than the detection signal generation unit 2 of the angle sensor 1 will be described. In addition to the detection signal generation unit 2, the angle sensor 1 includes the angle detection unit 3 and the state determination device 4 illustrated in FIG. FIG. 4 is a functional block diagram illustrating configurations of the angle detection unit 3 and the state determination device 4. The angle detection unit 3 generates an angle detection value θs having a correspondence relationship with the angle θ of the detection target based on the plurality of detection signals generated by the detection signal generation unit 2. The angle detection unit 3 and the state determination device 4 can be realized by, for example, an application specific integrated circuit (ASIC) or a microcomputer.

  The state determination device 4 includes a determination value generation unit 41 that generates a determination value used to determine whether or not the angle sensor 1 is in a predetermined state, and the angle sensor 1 is in a predetermined state based on the determination value. And a determination unit 42 for determining whether or not. In the present embodiment, in particular, the predetermined state is a state in which the angle sensor 1 has not failed. Therefore, the state determination device 4 detects a failure of the angle sensor 1. Hereinafter, a state in which the angle sensor 1 is not malfunctioning is referred to as a normal state.

  The angle detection unit 3 includes a conversion processing unit 31, a common correction processing unit 32, a non-common correction processing unit 33, and an angle calculation unit 34. The conversion processing unit 31 performs conversion processing for converting a plurality of detection signals into a plurality of pre-correction signals in which error components are reduced compared to each of the plurality of detection signals. The common correction processing unit 32 converts a plurality of pre-correction signals corresponding to a plurality of detection signals into a plurality of common post-correction signals used for generating the angle detection value θs and the determination value. I do. The non-common correction processing unit 33 uses a plurality of common corrected signals for the first angle calculation signal SC and the first angle calculation signal SC that are used for calculation for generating the angle detection value θs but are not used for generation of the determination value. A non-common correction process is performed for conversion into the angle calculation signal SD of 2. The angle calculation unit 34 calculates the detected angle value θs using the first and second angle calculation signals SC and SD.

  The determination value generation unit 41 generates a determination value based on a plurality of common corrected signals. In the common correction process, the angle error generated in the angle detection value θs is reduced compared to the case where the angle detection value θs is generated using a plurality of pre-correction signals without performing the common correction process, and the common correction process is performed. Compared to the case where determination values are generated using multiple uncorrected signals, the multiple variations of the uncorrected signals are corrected in common so that the variation range of the determined values according to the angle θ of the detection target is smaller. This is a process of converting into a post signal.

  In the present embodiment, the plurality of detection signals are the first to third detection signals S11, S12, and S13. The angle detection unit 3 further includes input ports P10, P20, and P30 to which detection signals S11, S12, and S13 are input, respectively.

  In the present embodiment, the plurality of pre-correction signals are the first pre-correction signal S1 and the second pre-correction signal S2. The conversion processing unit 31 includes two calculation units 31A and 31B. The calculation unit 31A performs a calculation for obtaining the sum of the first detection signal S11 and the second detection signal S12 input from the input ports P10 and P20 to generate the first pre-correction signal S1. The calculation unit 31B performs a calculation for obtaining the sum of the third detection signal S13 and the second detection signal S12 input from the input ports P30 and P20 to generate the second pre-correction signal S2. When the angle θ of the detection target changes with a predetermined period T, each of the first and second pre-correction signals S1 and S2 includes an ideal component that periodically changes so as to draw an ideal sine curve.

Hereinafter, the conversion processing in the conversion processing unit 31 will be specifically described. Here, it is assumed that each of the first to third detection signals S11, S12, and S13 includes an ideal component and an error component corresponding to the third harmonic with respect to the ideal component. First, the ideal component of the second detection signal S12 is cos θ. In this case, the error component of the second detection signal S12 can be expressed as a ₁ · cos 3θ. The first to third detection signals S11, S12, and S13 can be expressed by the following equations (1), (2), and (3), respectively. Note that the center value of each of the first to third detection signals S11, S12, and S13 is 0.

S11 = cos (θ−60 °) + a ₁ · cos {3 (θ−60 °)}
= Cos (θ-60 °) -a ₁ · cos 3θ (1)
S12 = cos θ + a ₁ · cos 3θ (2)
S13 = cos (θ + 60 °) + a ₁ · cos {3 (θ + 60 °)}
= Cos (θ + 60 °) −a ₁ · cos 3θ (3)

  The first and second pre-correction signals S1 and S2 are expressed by the following equations (1) to (3) using the first to third detection signals S11, S12, and S13, respectively. 4) and (5).

S1 = S11 + S12
= Cos (θ−60 °) −a ₁ · cos 3θ + cos θ + a ₁ · cos 3θ
= 2 cos (θ-30 °) · cos (-30 °)
= 1.73 cos (θ-30 °) (4)
S2 = S13 + S12
= Cos (θ + 60 °) −a ₁ · cos 3θ + cos θ + a ₁ · cos 3θ
= 2cos (θ + 30 °) ・ cos (30 °)
= 1.73 cos (θ + 30 °) (5)

  As shown in Expression (4), the error component of the first detection signal S11 and the error component of the second detection signal S12 are canceled when the first pre-correction signal S1 is generated. As a result, the first pre-correction signal S1 is a signal with a reduced error component compared to each of the first and second detection signals S11 and S12. Further, as shown in Expression (5), the error component of the second detection signal S12 and the error component of the third detection signal S13 are canceled when the second pre-correction signal S2 is generated. As a result, the second pre-correction signal S2 is a signal with a reduced error component compared to each of the second and third detection signals S12 and S13.

  Next, the configuration and operation of the common correction processing unit 32 and the content of the common correction processing will be described in detail with reference to FIG. FIG. 5 is a functional block diagram showing the configuration of the common correction processing unit 32. In the present embodiment, the plurality of common corrected signals are the first common corrected signal SA and the second common corrected signal SB. When the angle θ of the detection target changes with a predetermined period T, each of the first and second common corrected signals SA and SB includes an ideal component that periodically changes to draw an ideal sine curve. . The phase difference between the ideal component of the first common corrected signal SA and the ideal component of the second common corrected signal SB is 90 °. The amplitudes of the first common corrected signal SA and the second common corrected signal SB are equal. The common correction processing in the present embodiment is processing for converting the first and second pre-correction signals S1 and S2 into the first and second common post-correction signals SA and SB as described above.

  As shown in FIG. 5, the common correction processing unit 32 includes an offset correction unit 321, a normalization unit 322, and a phase difference correction unit 323. The offset correction unit 321 performs processing for correcting the offsets of the first and second pre-correction signals S1 and S2 to generate the signals S1a and S2a. Hereinafter, this processing is referred to as offset correction processing. The signals S1a and S2a are obtained by the following equations (6) and (7), respectively.

_{S1a = S1- (S1 max + S1} min) / 2 ... (6)
_{S2a = S2- (S2 max + S2} min) / 2 ... (7)

In Equation (6), S1 _max and S1 _min represent the maximum value and the minimum value of the first pre-correction signal S1, respectively. In Equation (7), S2 _max and S2 _min represent the maximum value and the minimum value of the second pre-correction signal S2, respectively. The maximum value S1 _max and the minimum value S1 _min can be obtained from the waveform of the first pre-correction signal S1 for at least one period. The maximum value S2 _max and the minimum value S2 _min can be obtained from the waveform of the second pre-correction signal S2 for at least one period. The waveforms of the first and second pre-correction signals S1 and S2 for at least one cycle can be generated before the angle sensor 1 is shipped or used.

  The normalization unit 322 performs processing for generating the signals S1b and S2b by normalizing the amplitudes of the first and second pre-correction signals S1 and S2. Hereinafter, this processing is referred to as normalization processing. The normalization process is performed using the signals S1a and S2a. The signals S1b and S2b are obtained by the following equations (8) and (9), respectively.

S1b = S1a / S1 _amp (8)
S2b = S2a / S2 _amp (9)

In Expression (8), S1 _amp represents the amplitude of the first pre-correction signal S1. In Expression (9), S2 _amp represents the amplitude of the second pre-correction signal S2. The amplitude S1 _amp can be obtained from the waveform of the first pre-correction signal S1 for at least one period. The amplitude S2 _amp can be obtained from the waveform of the second pre-correction signal S2 for at least one period.

  The phase difference correction unit 323 includes the ideal component of the first common corrected signal SA and the first component regardless of the phase difference between the ideal component of the first pre-correction signal S1 and the ideal component of the second pre-correction signal S2. The phase difference of the ideal component of the second common corrected signal SB is set to 90 °, and the amplitudes of the first common corrected signal SA and the second common corrected signal SB are made equal. Hereinafter, this process is referred to as a phase difference correction process. Specifically, the phase difference correction unit 323 first generates signals SAp and SBp by the following equations (10) and (11).

SAp = S1b + S2b (10)
SBp = S1b−S2b (11)

  Next, the phase difference correction unit 323 normalizes the amplitudes of the signals SAp and SBp by the following equations (12) and (13). As a result, the signals SAp and SBp become the first common corrected signal SA and the second common corrected signal SB, respectively.

SA = SAp / SAp _amp (12)
SB = SBp / SBp _amp (13)

In Expression (12), SAp _amp represents the amplitude of the signal SAp. In Expression (13), SBp _amp represents the amplitude of the signal SBp. The amplitude SAp _amp can be obtained from the waveform of the signal SAp for at least one period. The amplitude SBp _amp can be obtained from the waveform of the signal SBp for at least one period. The waveforms of the signals SAp and SBp for at least one cycle can be generated before the angle sensor 1 is shipped or used.

  As described above, when the ideal component of the second detection signal S12 is cos θ, the ideal component of the first common corrected signal SA is cos θ, and the ideal component of the second common corrected signal SB is sin θ. Become.

  Next, the configuration and operation of the non-common correction processing unit 33 and the contents of the non-common correction processing will be described in detail with reference to FIG. FIG. 6 is a functional block diagram showing the configuration of the non-common correction processing unit 33. The non-common correction processing in the present embodiment is angle detection as compared with the case where the angle detection value θs is generated using the first and second common corrected signals SA and SB without performing the non-common correction processing. This is a process for reducing the angle error that occurs in the value θs. The angle error reduced by the non-common correction process includes at least one of the first angle error component and the second angle error component. When the angle θ to be detected changes at a predetermined cycle T, the first angle error component changes at a cycle equal to the predetermined cycle T, and the second angle error component is 1/2 of the predetermined cycle T. It changes with period.

  As shown in FIG. 6, the non-common correction processing unit 33 includes a first amplitude difference generation unit 331, calculation units 332A and 332B, a second amplitude difference generation unit 333, and an offset generation unit 334. It is out. The first amplitude difference generation unit 331 adjusts the amplitudes of the first and second common corrected signals SA and SB to generate signals SAa and SBa. The signals SAa and SBa are obtained by the following equations (14) and (15), respectively.

SAa = SA / (1-C1) (14)
SBa = SB / (1 + C1) (15)

  Expressions (14) and (15) include a correction parameter C1. The correction parameter C1 is 0 or a value close to 0. When the correction parameter C1 is 0, the amplitudes of the signals SAa and SBa are equal. However, when the correction parameter C1 is other than 0, the amplitudes of the signals SAa and SBa are not equal. The correction parameter C1 is expressed by the following equation (16), for example.

  C1 = β · sin (s) (16)

  Β and s in Expression (16) will be described later.

  Arithmetic units 332A and 332B generate signals SCp and SDp by the following equations (17) and (18), respectively.

SCp = SAa−SBa (17)
SDp = SAa + SBa (18)

  Second amplitude difference generation section 333 adjusts the amplitudes of signals SCp and SDp to generate signals SCq and SDq. The signals SCq and SDq are obtained by the following equations (19) and (20), respectively.

SCq = SCp / {SCp _amp · (1-C2)} (19)
SDq = SDp / {SDp _amp · (1 + C2)} (20)

In Equation (19), SCp _amp represents the amplitude of the signal SCp. In Expression (20), SDp _amp represents the amplitude of the signal SDp. The amplitude SCp _amp can be obtained from the waveform of the signal SCp for at least one period. The amplitude SDp _amp can be obtained from the waveform of the signal SDp for at least one period. The waveforms of the signals SCp and SDp for at least one cycle can be generated before the angle sensor 1 is shipped or used.

  Expressions (19) and (20) include a correction parameter C2. The correction parameter C2 is 0 or a value close to 0.

  When the correction parameters C1 and C2 are both 0, the equations (17) to (20) are used to set the phase difference between the signals SCq and SDq to 90 ° and to make the amplitudes of the signals SCq and SDq equal. Represents an operation. When the correction parameter C1 is other than 0, the phase difference between the signals SCq and SDq does not become an accurate 90 °, but becomes a value close to 90 °. When the correction parameter C2 is other than 0, the amplitudes of the signals SCq and SDq are not equal.

  The correction parameter C2 is expressed by the following equation (21), for example.

  C2 = β · cos (s) (21)

  Β and s in equation (21) are the same as β and s in equation (16), respectively.

  The offset generation unit 334 adjusts the offsets of the signals SCp and SDp to generate the first and second angle calculation signals SC and SD. The first and second angle calculation signals SC and SD are obtained by the following equations (22) and (23), respectively.

SC = SCq + C3 (22)
SD = SDq-C4 (23)

  Expression (22) includes a correction parameter C3. Expression (23) includes a correction parameter C4. The correction parameters C3 and C4 are 0 or a value close to 0, respectively. When the correction parameter C3 is 0, no offset occurs in the first angle calculation signal SC. However, when the correction parameter C3 is other than 0, an offset occurs in the first angle calculation signal SC. When the correction parameter C4 is 0, no offset occurs in the second angle calculation signal SD, but when the correction parameter C4 is other than 0, an offset occurs in the second angle calculation signal SD. The correction parameters C3 and C4 are expressed by, for example, the following formulas (24) and (25), respectively.

C3 = SCq _amp · α · sin (t) (24)
C4 = SDq _amp · α · cos (t) (25)

In Expression (24), SCq _amp represents the amplitude of the signal SCq. In Expression (25), SDq _amp represents the amplitude of the signal SDq. The amplitude SCq _amp can be obtained from the waveform of the signal SCq for at least one period. The amplitude SDq _amp can be obtained from the waveform of the signal SDq for at least one period. The waveforms of the signals SCq and SDq for at least one cycle can be generated before the angle sensor 1 is shipped or used.

  Α and t in the equations (24) and (25) will be described later.

  Next, angle calculation in the angle calculation unit 34 will be described. The angle calculation unit 34 calculates the detected angle value θs using the first and second angle calculation signals SC and SD generated by the non-common correction processing unit 33. Specifically, for example, the angle calculation unit 34 calculates θs by the following equation (26). “Atan” represents an arc tangent.

  θs = atan (SD / SC) −φ (26)

  In Expression (26), φ represents the phase difference between the angle obtained by the calculation of atan (SD / SC) and the detected angle value θs. As described above, when the ideal component of the second detection signal S12 is cos θ, φ is, for example, 45 °.

  Within the range of θs between 0 ° and less than 360 °, the solution of θs in Equation (26) has two values that differ by 180 °. However, it is possible to determine which of the two solutions of θs in Equation (26) is the true value of θs by the combination of positive and negative of SC and SD. The angle calculation unit 34 obtains θs within a range of 0 ° or more and less than 360 ° by determining the combination of the expression (26) and the positive / negative of SC and SD described above.

  Next, the relationship between the first and second angle error components and the correction parameters C1 to C4 will be described. As described above, when the angle θ to be detected changes with a predetermined period T, the first angle error component changes with a period equal to the predetermined period T, and the second angle error component has a predetermined period. It changes with a period of 1/2 of T. Here, the first angle error component is defined as α · cos (θ−t), and the second angle error component is defined as β · cos {2 (θ−s / 2)}. α corresponds to the amplitude of the first angular error component. t corresponds to the phase of the first angular error component. β corresponds to the amplitude of the second angular error component. s corresponds to the phase of the second angular error component. α and β are values of 0 or more, respectively. α, t, β, and s can be obtained, for example, by obtaining an angle error waveform for at least one period of the detected angle value θs and performing Fourier transform on the angle error waveform.

The first angle error component includes a first component and a second component. The phase difference between the first component and the second component is 90 °. The amplitude of the first component is α · sin (t), and the amplitude of the second component is α · cos (t). The amplitude of the first component changes depending on the value of the correction parameter C3. Therefore, the first component can be reduced by adjusting the value of the correction parameter C3 according to the amplitude of the first component. Specifically, as shown in the equation (24), the product of the amplitude α · sin (t) of the first component and the amplitude SCq _{amp of the} signal SCq is used as the correction parameter C3, whereby the first Components can be reduced.

The amplitude of the second component changes depending on the value of the correction parameter C4. Therefore, the second component can be reduced by adjusting the value of the correction parameter C4 according to the amplitude of the second component. Specifically, as shown in the equation (25), the product of the amplitude α · cos (t) of the second component and the amplitude SDq _{amp of the} signal SDq is set as the correction parameter C4, so that the second Components can be reduced.

  If the first angle error component is sufficiently small, the correction parameters C3 and C4 may be set to 0, respectively.

  The second angle error component includes a third component and a fourth component. The phase difference between the third component and the fourth component is 45 °. The amplitude of the third component is β · sin (s), and the amplitude of the fourth component is β · cos (s). The amplitude of the third component changes depending on the value of the correction parameter C1. Therefore, the third component can be reduced by adjusting the value of the correction parameter C1 according to the amplitude of the third component. Specifically, as shown in Expression (16), the third component can be reduced by setting the amplitude β · sin (s) of the third component as the correction parameter C1.

  The amplitude of the fourth component changes depending on the value of the correction parameter C2. Therefore, the fourth component can be reduced by adjusting the value of the correction parameter C2 according to the amplitude of the fourth component. Specifically, as shown in Expression (21), the fourth component can be reduced by setting the amplitude β · cos (s) of the fourth component to the correction parameter C2.

  If the second angle error component is sufficiently small, the correction parameters C1 and C2 may be set to 0, respectively.

  Next, the operation of the state determination device 4 will be described with reference to FIG. The determination value generation unit 41 generates a determination value dLr based on the first and second common corrected signals SA and SB. In the present embodiment, in particular, the determination value generation unit 41 performs an operation including obtaining the sum of the square of the first common corrected signal SA and the square of the second common corrected signal SB. The value dLr is generated. The “calculation including obtaining the sum of the square of the first common corrected signal SA and the square of the second common corrected signal SB” includes the square of the first common corrected signal SA, 2 after obtaining the sum of the squares of the two common corrected signals SB and multiplying a predetermined coefficient or adding or subtracting a predetermined value.

  Hereinafter, the calculation for generating the determination value dLr will be specifically described. First, the determination value generation unit 41 performs an operation represented by the following equation (27) to generate an initial determination value Lr.

Lr = SA ² + SB ² (27)

  Next, the determination value generation unit 41 performs a calculation represented by the following equation (28) to generate a determination value dLr.

  dLr = Lr−Lrav (28)

  Lrav in Expression (28) is an average value of the initial determination value Lr when the angle θ of the detection target changes from 0 ° to 360 ° when the angle sensor 1 is in a normal state. The average value Lrav is determined according to the measurement result obtained by measuring the initial determination value Lr before shipping the angle sensor 1 which is not in failure, for example.

  When the first and second common corrected signals SA and SB are both composed only of ideal components and the angle sensor 1 is not in failure, the determination value dLr is composed only of ideal value components. This ideal value component is a constant value, specifically 0, regardless of the angle θ of the detection target.

  When the first and second common corrected signals SA and SB are both composed only of ideal components and the angle sensor 1 is not broken, the determination value dLr is different from the ideal value component. Can be. When the determination value dLr becomes a value different from the ideal value component, the determination value dLr may vary according to the angle θ of the detection target.

  The determination unit 42 determines whether or not the angle sensor 1 is in a predetermined state based on the determination value dLr. Specifically, the determination unit 42 determines that the angle sensor 1 is in a normal state when the determination value dLr is within a predetermined determination range, and otherwise the angle sensor 1 fails. A signal indicating the determination result is output. The determination range is a range from −LTH to LTH, where LTH is a predetermined positive value. The determination range is set before shipment of the angle sensor 1 that is not out of order.

  As described above, in the present embodiment, the first and second pre-correction signals having a correspondence relationship with the first to third detection signals S11, S12, and S13 by the common correction process in the common correction processing unit 32. S1 and S2 are converted into first and second common corrected signals SA and SB, and the first and second common corrected signals SA and SB are used to generate the angle detection value θs and the determination value dLr. Generate. Particularly in the present embodiment, the common correction process includes an offset correction process, a normalization process, and a phase difference correction process. Thereby, according to the present embodiment, at least one of the center value, the amplitude, and the phase is deviated from a desired value in at least one of the first and second pre-correction signals S1 and S2. Thus, the angle error in the normal state can be reduced, and the variation range of the determination value dLr according to the angle θ of the detection target can be reduced. Thereby, according to this Embodiment, the state of the angle sensor 1 can be discriminate | determined accurately. Hereinafter, the fluctuation range of the determination value dLr corresponding to the angle θ of the detection target is referred to as the fluctuation range of the determination value dLr.

  In the present embodiment, the first to third detection signals S11, S12, and S13 are converted into error components by the conversion process in the conversion processing unit 31 as compared with the first to third detection signals S11, S12, and S13. Are converted into first and second pre-correction signals S1 and S2. Also according to this embodiment, the angular error in the normal state can be reduced and the fluctuation range of the determination value dLr can be reduced.

  In the present embodiment, the angle correction and the variation range of the determination value dLr are simultaneously reduced by the common correction process performed by one common correction processing unit 32. Therefore, according to the present embodiment, the configuration of the angle sensor 1 is simplified as compared with the case where the processing for reducing the angle error and the processing for reducing the fluctuation range of the determination value dLr are performed separately. Can do.

  In the present embodiment, the angle detection unit 3 includes a non-common correction processing unit 33. The non-common correction processing unit 33 converts the first and second common corrected signals SA and SB into first and second angle calculation signals SC and SD. The first and second common corrected signals SA and SB are two signals having a phase difference between their ideal components of 90 ° and an equal amplitude. However, depending on the values of the correction parameters C1 to C4, the first and second angle calculation signals SC and SD are not necessarily two signals having an ideal component having a phase difference of 90 ° and an equal amplitude. . Therefore, if the determination value dLr is generated using the first and second angle calculation signals SC and SD, the determination value dLr is calculated using the first and second common corrected signals SA and SB. There is a possibility that the fluctuation range of the determination value dLr may be larger than when it is generated. In the present embodiment, the first and second angle calculation signals SC and SD are used for calculation for generating the angle detection value θs, but are not used for generation of the determination value dLr. Thereby, according to the present embodiment, it is possible to further reduce the angle error while reducing the fluctuation range of the determination value dLr.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The angle sensor 1 according to the present embodiment includes a detection signal generation unit 102 and an angle detection unit 103 instead of the detection signal generation unit 2 and the angle detection unit 3 in the first embodiment.

  First, the detection signal generation unit 102 will be described with reference to FIG. FIG. 8 is a circuit diagram illustrating a configuration of the detection signal generation unit 102. The detection signal generation unit 102 generates first to fourth detection signals S21, S22, S23, and S24 each having a corresponding relationship with the angle θ of the detection target. The detection signal generation unit 102 generates a first detection circuit 110 that generates a first detection signal S21, a second detection circuit 120 that generates a second detection signal S22, and a third detection signal S23. A third detection circuit 130 and a fourth detection circuit 140 that generates a fourth detection signal S24 are included. Each of the first to fourth detection circuits 110, 120, 130, and 140 includes at least one magnetic detection element that detects the rotating magnetic field MF. The detection signal generation unit 102 further includes a power supply port V and a ground port G. A power supply voltage of a predetermined magnitude such as 5 V is applied between the power supply port V and the ground port G.

  When the direction DM of the rotating magnetic field MF rotates with a predetermined period T, the angle θ of the detection target changes with the predetermined period T. In this case, all of the first to fourth detection signals S21, S22, S23, and S24 periodically change with a signal period equal to the predetermined period T. The first to fourth detection signals S21, S22, S23, and S24 have different phases.

  The first detection circuit 110 has a pair of magnetic detection elements R111 and R112 connected in series, and an output port E110. One end of the magnetic detection element R111 is connected to the power supply port V. The other end of the magnetic detection element R111 is connected to one end of the magnetic detection element R112 and the output port E110. The other end of the magnetic detection element R112 is connected to the ground port G. The output port E110 outputs a first detection signal S21 corresponding to the potential at the connection point of the magnetic detection elements R111 and R112.

  The second detection circuit 120 has a pair of magnetic detection elements R121 and R122 connected in series, and an output port E120. One end of the magnetic detection element R121 is connected to the power supply port V. The other end of the magnetic detection element R121 is connected to one end of the magnetic detection element R122 and the output port E120. The other end of the magnetic detection element R122 is connected to the ground port G. The output port E120 outputs a second detection signal S22 corresponding to the potential at the connection point of the magnetic detection elements R121 and R122.

  The third detection circuit 130 has a pair of magnetic detection elements R131 and R132 connected in series, and an output port E130. One end of the magnetic detection element R131 is connected to the power supply port V. The other end of the magnetic detection element R131 is connected to one end of the magnetic detection element R132 and the output port E130. The other end of the magnetic detection element R132 is connected to the ground port G. The output port E130 outputs a third detection signal S23 corresponding to the potential at the connection point of the magnetic detection elements R131 and R132.

  The fourth detection circuit 140 has a pair of magnetic detection elements R141 and R142 connected in series, and an output port E140. One end of the magnetic detection element R141 is connected to the power supply port V. The other end of the magnetic detection element R141 is connected to one end of the magnetic detection element R142 and the output port E140. The other end of the magnetic detection element R142 is connected to the ground port G. The output port E140 outputs a fourth detection signal S24 corresponding to the potential at the connection point of the magnetic detection elements R141 and R142.

  The configuration of each of the magnetic detection elements R111, R112, R121, R122, R131, R132, R141, and R142 is the magnetic detection elements R11, R12, and R21 in the first embodiment except for the magnetization direction of the magnetization fixed layer. , R22, R31, R32 are the same as the respective configurations.

  In the first detection circuit 110, the magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R111 is the X direction. Hereinafter, this direction is referred to as a first direction D11. The magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R112 is the direction opposite to the first direction D11, that is, the −X direction. In the first detection circuit 110, the potential at the connection point of the magnetic detection elements R111 and R112 changes according to the intensity of the component in the first direction D11 of the rotating magnetic field MF. Therefore, the first detection circuit 110 detects the intensity of the component in the first direction D11 of the rotating magnetic field MF, and outputs a signal representing the intensity as the first detection signal S21. The intensity of the component in the first direction D11 of the rotating magnetic field MF has a corresponding relationship with the angle θ of the detection target.

  In the second detection circuit 120, the magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R121 is the −X direction. Hereinafter, this direction is referred to as a second direction D12. The magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R122 is the direction opposite to the second direction D12, that is, the X direction. In the second detection circuit 120, the potential at the connection point of the magnetic detection elements R121 and R122 changes according to the intensity of the component in the second direction D12 of the rotating magnetic field MF. Therefore, the second detection circuit 120 detects the intensity of the component in the second direction D12 of the rotating magnetic field MF, and outputs a signal representing the intensity as the second detection signal S22. The intensity of the component in the second direction D12 of the rotating magnetic field MF has a corresponding relationship with the angle θ of the detection target.

  In the third detection circuit 130, the magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R131 is the Y direction. Hereinafter, this direction is referred to as a third direction D13. The magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R132 is the direction opposite to the third direction D13, that is, the −Y direction. In the third detection circuit 130, the potential at the connection point of the magnetic detection elements R131 and R132 changes according to the intensity of the component in the third direction D13 of the rotating magnetic field MF. Therefore, the third detection circuit 130 detects the intensity of the component in the third direction D13 of the rotating magnetic field MF, and outputs a signal representing the intensity as the third detection signal S23. The intensity of the component in the third direction D13 of the rotating magnetic field MF has a corresponding relationship with the angle θ of the detection target.

  In the fourth detection circuit 140, the magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R141 is the −Y direction. Hereinafter, this direction is referred to as a fourth direction D14. The magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R142 is the direction opposite to the fourth direction D14, that is, the Y direction. In the fourth detection circuit 140, the potential at the connection point of the magnetic detection elements R141 and R142 changes according to the intensity of the component in the fourth direction D14 of the rotating magnetic field MF. Therefore, the fourth detection circuit 140 detects the intensity of the component in the fourth direction D14 of the rotating magnetic field MF, and outputs a signal representing the intensity as the fourth detection signal S24. The intensity of the component in the fourth direction D14 of the rotating magnetic field MF has a corresponding relationship with the angle θ of the detection target.

  Note that the magnetization direction of the magnetization fixed layer in the plurality of MR elements in the detection circuits 110, 120, 130, and 140 may be slightly deviated from the above-described direction from the viewpoint of the accuracy of manufacturing the MR element.

  When the angle θ of the detection target changes at a predetermined period T, each of the detection signals S21, S22, S23, and S24 includes an ideal component and an error component. The detection signals S21, S22, S23, and S24 are such that their ideal components have different phases and have a predetermined phase relationship. In the present embodiment, in particular, in the detection signals S21 and S22, the phases of their ideal components differ from each other by 180 °. In the detection signals S21 and S23, the phases of these ideal components are 90 ° different from each other. In the detection signals S23 and S24, the phases of these ideal components differ from each other by 180 °.

  Next, the angle detection unit 103 will be described with reference to FIG. FIG. 9 is a functional block diagram illustrating configurations of the angle detection unit 103 and the state determination device 4. Based on the first to fourth detection signals S21, S22, S23, and S24 generated by the detection signal generation unit 102, the angle detection unit 103 generates an angle detection value θs that has a corresponding relationship with the angle θ of the detection target. To do. The configuration and operation of the state determination device 4 are the same as those in the first embodiment. The angle detection unit 103 and the state determination device 4 can be realized by, for example, an application specific integrated circuit (ASIC) or a microcomputer.

  The angle detection unit 103 includes input ports P110, P120, P130, and P140, a conversion processing unit 131, a common correction processing unit 132, a non-common correction processing unit 133, and an angle calculation unit 134. The first to fourth detection signals S21, S22, S23, and S24 are input to the input ports P110, P120, P130, and P140, respectively.

  The conversion processing unit 131 includes two calculation units 131A and 131B. The calculation unit 131A performs a calculation for obtaining a difference between the first detection signal S21 and the second detection signal S22 input from the input ports P110 and P120, and generates the first pre-correction signal S1. The calculation unit 131B performs a calculation for obtaining a difference between the third detection signal S23 and the fourth detection signal S24 input from the input ports P130 and P140, and generates a second pre-correction signal S2. The first and second pre-correction signals S1 and S2 are obtained by the following equations (29) and (30), respectively.

S1 = S21-S22 (29)
S2 = S23−S24 (30)

  When each of the detection signals S21, S22, S23, and S24 includes an error component corresponding to the third harmonic relative to the ideal component, in the calculations shown in the equations (29) and (30), the detection signals S21, S22, S23, Each error component of S24 is not canceled out. In the present embodiment, when the angle θ of the detection target changes with a predetermined period T, each of the first and second pre-correction signals S1 and S2 includes the third harmonic with respect to the ideal component in addition to the ideal component. The error component corresponding to is included.

  The common correction processing unit 132 generates the angle detection value θs and the determination value for the first and second pre-correction signals S1 and S2 having a correspondence relationship with the first to fourth detection signals S21, S22, S23, and S24. A common correction process is performed to convert the first and second common corrected signals SA and SB used for dLr generation.

  The configurations and operations of the non-common correction processing unit 133 and the angle calculation unit 134 are the same as those of the non-common correction processing unit 33 and the angle calculation unit 34 in the first embodiment. In other words, the non-common correction processing unit 133 uses the first and second common corrected signals SA and SB for calculation for generating the angle detection value θs, but not for generating the determination value dLr. Non-common correction processing for converting the first and second angle calculation signals SC and SD is performed. The angle calculator 134 calculates the detected angle value θs using the first and second angle calculation signals SC and SD.

  Next, the configuration and operation of the common correction processing unit 132 and the content of the common correction processing in the present embodiment will be described in detail with reference to FIG. FIG. 10 is a functional block diagram showing the configuration of the common correction processing unit 132. As shown in FIG. 10, the common correction processing unit 132 includes an offset correction unit 1321, a normalization unit 1322, a phase difference correction unit 1323, and an error component reduction unit 1324. The operations of the offset correction unit 1321 and the normalization unit 1322 are the same as the operations of the offset correction unit 321 and the normalization unit 322 in the first embodiment.

  The phase difference correction unit 1323 performs phase difference correction processing. Specifically, the phase difference correction unit 1323 first generates signals SAp and SBp according to the following equations (31) and (32) using the signals S1b and S2b generated by the normalization unit 1322.

SAp = S1b-S2b (31)
SBp = S1b + S2b (32)

  Next, the phase difference correction unit 1323 normalizes the amplitudes of the signals SAp and SBp to generate the signals SAq and SBq. The signals SAq and SBq are obtained by the following equations (33) and (34), respectively.

SAq = SAp / SAp _max (33)
SBq = SBp / SBp _max (34)

  The error component reduction unit 1324 performs a process of reducing the error component included in each of the first and second common post-correction signals SA and SB compared to each of the first and second pre-correction signals S1 and S2. . Error component reduction section 1324 converts signals SAq and SBq into first and second common corrected signals SA and SB.

  Among the error components included in each of the first and second pre-correction signals S1 and S2, the error component reduced by the error component reduction unit 1324 is an error component corresponding to the third harmonic with respect to the ideal component, Further, it is an error component that distorts the waveform of the first pre-correction signal S1 and the waveform of the second pre-correction signal S2 in the same way. Hereinafter, this error component is referred to as a first third harmonic error component. The first third harmonic error component becomes a factor that increases the angle error and a factor that increases the fluctuation range of the determination value dLr.

Here, the ideal component of the signal SAq is cos θ, and the ideal component of the signal SBq is sin θ. The signals SAq and SBq can be expressed by the following equations (35) and (36), respectively. “A ₁ · cos 3θ” in the equation (35) is a first third harmonic error component of the signal SAq, and “A ₁ · sin (3θ−180 °)” in the equation (36) This is the first third harmonic error component of SBq.

SAq = cos θ + A ₁ · cos 3θ (35)
SBq = sin θ + A ₁ · sin (3θ−180 °) (36)

  The error component reduction unit 1324 generates the first common corrected signal SA by subtracting the estimated value of the first third harmonic error component of the signal SAq from the signal SAq. In addition, the error component reduction unit 1324 generates the second common corrected signal SB by subtracting the estimated value of the first third harmonic error component of the signal SBq from the signal SBq. The first and second common corrected signals SA and SB are obtained by the following equations (37) and (38), respectively.

SA = SAq−F ₁ · cos 3θq (37)
SB = SBq−F ₁ · sin (3θq−180 °) (38)

The value F ₁ in the equations (37) and (38) can be obtained, for example, from the fluctuation component of the sum of the square of the signal SAq and the square of the signal SBq. Hereinafter, the sum of the square of the signal SAq and the square of the signal SBq is referred to as a square sum signal. The square sum signal can be expressed by the following equation (39) using signals SAq and SBq expressed by equations (35) and (36).

SAq ² + SBq ² = (cos θ + A ₁ · cos 3θ) ²
+ {Sin θ + A ₁ · sin (3θ−180 °)} ²
= Cos ² θ + 2A ₁ · cos θ · cos 3θ + A ₁ ² · cos ² 3θ
+ Sin ² θ−2A ₁ · sin θ · sin 3θ + A ₁ ² · sin ² 3θ
= 1 + A ₁ ²
+ A ₁ {cos (−2θ) + cos4θ}
−A ₁ {cos (−2θ) −cos4θ}
= 1 + A ₁ ² + 2A ₁ · cos 4θ (39)

From equation (39), the fluctuation component of the sum of squares signal is “2A ₁ · cos 4θ”. Therefore, the value A ₁ can be obtained from the waveform of the sum-of-squares signal corresponding to at least a quarter of the angle θ of the detection target. In the present embodiment, the value A ₁ obtained in this way is set as a value F ₁ . The waveform of the square sum signal can be generated before shipment or use of the angle sensor 1.

  Further, θq in the equations (37) and (38) is calculated by the following equation (40) using the signals SAq and SBq.

  θq = atan (SBq / SAq) (40)

  When θq is in the range of 0 ° to less than 360 °, the solution of θq in Equation (40) has two values that differ by 180 °. However, according to the positive / negative combination of SAq and SBq, it is possible to determine which of the two solutions of θq in Expression (40) is the true value of θq. The error component reduction unit 1324 obtains θq within a range of 0 ° or more and less than 360 ° based on the determination of the expression (40) and the positive / negative combination of SAq and SBq.

  The error component reduction unit 1324 obtains θq from the signals SAq and SBq using Expression (40), and substitutes θq into Expressions (37) and (38) to substitute the first and second common corrected signals SA, SB may be generated.

  Alternatively, the error component reducing unit 1324 may generate the first and second common corrected signals SA and SB as follows without obtaining θq. When Expressions (37) and (38) are modified, the following Expressions (41) and (42) are obtained.

SA = SAq−F ₁ (4 cos ³ θq− ³ cos θq) (41)
SB = SBq−F ₁ (4 sin ³ θq− ³ sin θq) (42)

  The error component reduction unit 1324 may generate the first common corrected signal SA by replacing cos θq in Equation (41) with the signal SAq. Further, the error component reduction unit 1324 may generate the second common corrected signal SB by replacing sin θq in the equation (42) with the signal SBq.

  As described above, in the present embodiment, the error component reduction unit 1324 causes the first and second common post-correction signals SA and SB to be compared with each of the first and second pre-correction signals S1 and S2. The first third harmonic error component included in each is reduced. Thereby, according to the present embodiment, the angle error in the normal state can be further reduced, and the fluctuation range of the determination value dLr can be further reduced.

  Other configurations, 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. In the angle sensor 1 according to the present embodiment, the configuration of the non-common correction processing unit 133 is different from that of the second embodiment. FIG. 11 is a functional block diagram illustrating the configuration of the non-common correction processing unit 133. As illustrated in FIG. 11, the non-common correction processing unit 133 includes an error component reduction unit 1330, a first amplitude difference generation unit 1331, arithmetic units 1332A and 1332B, a second amplitude difference generation unit 1333, An offset generation unit 1334 is included.

  In the present embodiment, the angle error reduced by the non-common correction process includes a third angle error component. When the angle θ to be detected changes at a predetermined period T, the third angle error component changes at a quarter of the predetermined period T. Each of the first and second common corrected signals SA and SB includes an error component that causes a third angular error component. This error component is an error component that cannot be reduced by the error component reduction unit 1324 shown in FIG. 10 in the second embodiment.

  Hereinafter, the error component that causes the third angle error component will be described in detail. This error component occurs in the signals SAq and SBq in the same phase, and does not cause a change in the square sum signal described in the second embodiment. For example, this error component has a magnetic anisotropy in the same direction in the free layer of the MR element included in each of the first to fourth detection circuits 110, 120, 130, and 140 (see FIG. 8). This occurs when the positional relationship between the magnet 6 (see FIG. 1) and the detection signal generation unit 102 (see FIG. 8) is shifted.

Here, the ideal component of the first common corrected signal SA is cos θ, and the ideal component of the second common corrected signal SB is sin θ. When each of the first and second common corrected signals SA and SB includes an error component that generates a third angular error component, the first and second common corrected signals SA and SB are respectively It is expressed by equations (43) and (44). In Expressions (43) and (44), A ₂ represents the amplitude of the third angular error component when expressed in radians, and δ represents the phase of the third angular error component.

SA = cos {θ−A ₂ · sin (4θ−δ)}
= Cos θ · cos {A ₂ · sin (4θ−δ)}
+ Sin θ · sin {A ₂ · sin (4θ−δ)} (43)
SB = sin {θ−A ₂ · sin (4θ−δ)}
= Sin θ · cos {A ₂ · sin (4θ−δ)}
−cos θ · sin {A ₂ · sin (4θ−δ)} (44)

By the way, when the angle x expressed in radians is sufficiently small, cosx and sinx can be approximated as 1 and x, respectively. In the present embodiment, the value of A ₂ is a small value that can approximate cos (A ₂ · sin 4θ) and sin (A ₂ · sin 4θ) to 1 and A ₂ · sin 4θ, respectively. When this approximation is applied to the equations (43) and (44), the first and second common corrected signals SA and SB are expressed by the following equations (45) and (46), respectively.

SA≈cos θ + sin θ · A ₂ · sin (4θ−δ)
_{= Cosθ- (A 2/2)} {cos (5θ-δ) -cos (-3θ + δ)}
_{= Cosθ + (A 2/2} ) cos (3θ-δ) - (A 2/2) cos (5θ-δ)
... (45)
SB≈sin θ−cos θ · A ₂ · sin (4θ−δ)
_{= Sinθ- (A 2/2)} {sin (5θ-δ) -sin (-3θ + δ)}
_{= Sinθ- (A 2/2)} sin (3θ-δ) - (A 2/2) sin (5θ-δ)
... (46)

  The first common corrected signal SA has an error component corresponding to the third harmonic with respect to the ideal component of the first common corrected signal SA and a fifth harmonic with respect to the ideal component of the first common corrected signal SA. Corresponding error components. The second common corrected signal SB has an error component corresponding to the third harmonic with respect to the ideal component of the second common corrected signal SB and a fifth harmonic with respect to the ideal component of the second common corrected signal SB. Corresponding error components. Hereinafter, an error component corresponding to the third harmonic included in each of the first and second common corrected signals SA and SB is referred to as a second third harmonic error component. An error component corresponding to the fifth harmonic contained in each of the first and second common corrected signals SA and SB is referred to as a fifth harmonic error component.

In the formula _{(45) "(A 2/} 2) cos (3θ-δ)" is a second third harmonic error component of the first common corrected signal SA. In the formula _{(45) "- (A 2} /2) cos (5θ-δ)" is the fifth harmonic error component of the first common corrected signal SA. In the formula _{(46) "- (A 2} /2) sin (3θ-δ)" is a second third harmonic error component of the second common corrected signal SB. In the formula _{(45) "- (A 2} /2) sin (5θ-δ)" is the fifth harmonic error component of the second common corrected signal SB.

  The error component reducing unit 1330 performs a process of correcting the first and second common corrected signals SA and SB so as to generate the signals SAe and SBe so that the third angle error component is reduced. The error component reduction unit 1330 combines the first common corrected signal SA and the correction value CA to generate a signal SAe. Further, the error component reducing unit 1330 combines the second common corrected signal SB and the correction value CB to generate a signal SBe. The signals SAe and SBe are obtained by the following equations (47) and (48), respectively.

SAe = SA + CA (47)
SBe = SB + CB (48)

  Further, the correction values CA and CB are represented by, for example, the following formulas (49) and (50), respectively.

CA = −F ₂ · cos (3θa−δ) (49)
CB = −F ₂ · sin (3θa−180 ° −δ) (50)

F ₂ in the equations (49) and (50) can be determined based on the amplitude A ₂ of the third angular error component. In the present embodiment, the amplitude A ₂ of the third angle error component is set to a value F ₂ . The amplitude A ₂ of the third angle error component can be obtained from the waveform of the angle error. The waveform of the angle error can be generated before the angle sensor 1 is shipped or used.

  Further, θa in the equations (49) and (50) is calculated by the following equation (51) using the first and second common corrected signals SA and SB.

  θa = atan (SB / SA) (51)

  Within the range of θa between 0 ° and less than 360 °, the solution of θa in equation (51) has two values that differ by 180 °. However, it is possible to determine which of the two solutions of θa in Equation (51) is the true value of θa by the positive / negative combination of SA and SB. The error component reduction unit 1330 obtains θa within a range of 0 ° or more and less than 360 ° based on the determination of Expression (51) and the positive / negative combination of SA and SB.

  The error component reduction unit 1330 obtains θa from the first and second common corrected signals SA and SB using the equation (51), substitutes this θa into the equations (49) and (50), and corrects the correction value CA. , CB may be obtained.

  Alternatively, the error component reduction unit 1330 may obtain the correction values CA and CB as follows without obtaining θa. When formulas (49) and (50) are modified, the following formulas (52) and (53) are obtained.

CA = −F ₂ (cos 3θa · cos (−δ) −sin 3θa · sin (−δ))
= -F ₂ cos δ (4 cos ³ θa- ³ cos θa)
+ F ₂ sin δ (4 sin ³ θa− ³ sin θa) (52)
CB = F ₂ (sin3θa · cos (−δ) + cos3θa · sin (−δ))
= −F ₂ cos δ (4 sin ³ θa− ³ sin θa)
-F ₂ sin δ (4 cos ³ θa- ³ cos θa) (53)

  The error component reduction unit 1330 replaces cos θa in the equations (52) and (53) with the first common corrected signal SA, and replaces sin θa in the equations (52) and (53) with the second common corrected signal SB. Thus, the correction values CA and CB may be obtained.

In the correction values CA and CB shown in equations (49) and (50), the amplitude of the correction value CA and the amplitude of the correction value CB are the same value F ₂ , and the period of the correction value CA and the correction value CB The period is the same value as 1/3 of the predetermined period T. In the present embodiment, the period of the correction value CA and the period of the correction value CB may be the same value that is 1/5 of the predetermined period T. In this case, the correction values CA and CB are expressed by the following formulas (54) and (55), respectively.

CA = F ₂ · cos (5θa−δ) (54)
CB = −F ₂ · sin (5θa−180 ° −δ) (55)

  Next, the operation of the non-common correction processing unit 133 other than the error component reduction unit 1330 will be described. The operation of the first amplitude difference generation unit 1331 is the same as that of the first amplitude difference generation unit 331 in the first embodiment except for the following points. In the present embodiment, the first amplitude difference generation unit 1331 adjusts the amplitudes of the signals SAe and SBe to generate the signals SAa and SBa. The operations of the arithmetic units 1332A and 1332B, the second amplitude difference generation unit 1333, and the offset generation unit 1334 are respectively the arithmetic units 332A and 332B, the second amplitude difference generation unit 333, and the offset generation unit in the first embodiment. This is the same as the operation at 334.

As described above, according to this embodiment, the third angle error component can be reduced by the error component reduction unit 1330. In the present embodiment, although the first common post-correction signal SA includes the second third harmonic error component and the fifth harmonic error component, the correction value CA is one cycle. It can be a variable value. Similarly, although the second common corrected signal SB includes the second third harmonic error component and the fifth harmonic error component, the correction value CB is a value that changes in one cycle. It's okay. Amplitude and amplitude of the correction value CB of the correction value CA is the same value F _2. The period of the correction value CA and the period of the correction value CB are the same value of 1/3 or 1/5 of the predetermined period T. Thus, according to the present embodiment, it is possible to reduce the third angle error component with a simple process.

  If the determination value dLr is generated using the signals SAe and SBe generated by the error component reduction unit 1330, the determination value dLr is calculated using the first and second common corrected signals SA and SB. There is a possibility that the fluctuation range of the determination value dLr may be larger than when it is generated. In the present embodiment, the error component reduction unit 1330 is included in the non-common correction processing unit 133 instead of the common correction processing unit 132. Thereby, according to the present embodiment, it is possible to further reduce the angle error while reducing the fluctuation range of the determination value dLr.

  Other configurations, operations, and effects in the present embodiment are the same as those in the first or second embodiment.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. The angle sensor 1 according to the present embodiment includes a detection signal generation unit 202 and an angle detection unit 203 instead of the detection signal generation unit 2 and the angle detection unit 3 in the first embodiment.

  First, the detection signal generation unit 202 will be described with reference to FIG. FIG. 12 is a circuit diagram illustrating a configuration of the detection signal generation unit 202. The detection signal generation unit 202 generates first and second detection signals S31 and S32 each having a corresponding relationship with the angle θ of the detection target. The detection signal generation unit 202 includes a first detection circuit 210 that generates a first detection signal S31 and a second detection circuit 220 that generates a second detection signal S32. Each of the first and second detection circuits 210 and 220 includes at least one magnetic detection element that detects the rotating magnetic field MF. The detection signal generation unit 202 further includes a power supply port V and a ground port G. A power supply voltage of a predetermined magnitude such as 5 V is applied between the power supply port V and the ground port G.

  When the direction DM of the rotating magnetic field MF rotates with a predetermined period T, the angle θ of the detection target changes with the predetermined period T. In this case, both the first and second detection signals S31 and S32 periodically change with a signal period equal to the predetermined period T. The first and second detection signals S31 and S32 have different phases.

  The first detection circuit 210 has a pair of magnetic detection elements R211 and R212 connected in series, and an output port E210. One end of the magnetic detection element R211 is connected to the power supply port V. The other end of the magnetic detection element R211 is connected to one end of the magnetic detection element R212 and the output port E210. The other end of the magnetic detection element R212 is connected to the ground port G. The output port E210 outputs a first detection signal S31 corresponding to the potential at the connection point of the magnetic detection elements R211 and R212.

  The second detection circuit 220 includes a pair of magnetic detection elements R221 and R222 connected in series, and an output port E220. One end of the magnetic detection element R221 is connected to the power supply port V. The other end of the magnetic detection element R221 is connected to one end of the magnetic detection element R222 and the output port E220. The other end of the magnetic detection element R222 is connected to the ground port G. The output port E220 outputs a second detection signal S32 corresponding to the potential at the connection point of the magnetic detection elements R221 and R222.

  The configuration of each of the magnetic detection elements R211, R212, R221, and R222 is the same as that of each of the magnetic detection elements R11, R12, R21, R22, R31, and R32 in the first embodiment except for the magnetization direction of the magnetization fixed layer. The configuration is the same.

  In the first detection circuit 210, the magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R211 is the X direction. Hereinafter, this direction is referred to as a first direction D21. The magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R212 is opposite to the first direction D21, that is, in the −X direction. In the first detection circuit 210, the potential at the connection point of the magnetic detection elements R211 and R212 changes according to the intensity of the component in the first direction D21 of the rotating magnetic field MF. Accordingly, the first detection circuit 210 detects the intensity of the component in the first direction D21 of the rotating magnetic field MF, and outputs a signal representing the intensity as the first detection signal S31. The intensity of the component in the first direction D21 of the rotating magnetic field MF has a corresponding relationship with the angle θ of the detection target.

  In the second detection circuit 220, the magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R221 is the Y direction. Hereinafter, this direction is referred to as a second direction D22. The magnetization direction of the magnetization fixed layer in the plurality of MR elements included in the magnetic detection element R222 is the direction opposite to the second direction D22, that is, the −Y direction. In the second detection circuit 220, the potential at the connection point of the magnetic detection elements R221 and R222 changes according to the intensity of the component in the second direction D22 of the rotating magnetic field MF. Accordingly, the second detection circuit 220 detects the intensity of the component in the second direction D22 of the rotating magnetic field MF, and outputs a signal representing the intensity as the second detection signal S32. The intensity of the component in the second direction D22 of the rotating magnetic field MF has a corresponding relationship with the angle θ of the detection target.

  Note that the magnetization direction of the magnetization fixed layer in the plurality of MR elements in the detection circuits 210 and 220 may be slightly deviated from the above-mentioned direction from the viewpoint of the accuracy of manufacturing the MR element.

  When the angle θ of the detection target changes at a predetermined period T, each of the detection signals S31 and S32 includes an ideal component and an error component. The detection signals S31 and S32 are those in which the phases of their ideal components are different from each other and have a predetermined phase relationship. Particularly in the present embodiment, the detection signals S31 and S32 are such that the phases of their ideal components differ from each other by 90 °.

  Next, the angle detection unit 203 will be described with reference to FIG. FIG. 13 is a functional block diagram illustrating configurations of the angle detection unit 203 and the state determination device 4. Based on the first and second detection signals S31 and S32 generated by the detection signal generation unit 202, the angle detection unit 203 generates an angle detection value θs that has a corresponding relationship with the angle θ of the detection target. The configuration and operation of the state determination device 4 are the same as those in the first embodiment. The angle detection unit 203 and the state determination device 4 can be realized by, for example, an application specific integrated circuit (ASIC) or a microcomputer.

  The angle detection unit 203 includes input ports P210 and P220, a common correction processing unit 231, a non-common correction processing unit 232, and an angle calculation unit 233. The first and second detection signals S31 and S32 are input to the input ports P210 and P220, respectively.

  The configuration and operation of the common correction processing unit 231 are the same as those of the common correction processing unit 132 shown in FIG. 10 in the second embodiment. In the present embodiment, the first and second detection signals S31 and S32 themselves are a plurality of pre-correction signals. Therefore, the common correction processing unit 231 uses the first and second detection signals S31 and S32 as the first and second common corrected signals SA, used for generation of the angle detection value θs and generation of the determination value dLr. A common correction process for converting to SB is performed.

  The configuration and operation of the non-common correction processing unit 232 may be the same as the non-common correction processing unit 133 in the second embodiment or the same as the non-common correction processing unit 133 in the third embodiment. There may be. The configuration and operation of the angle calculator 233 are the same as those of the angle calculator 34 in the first embodiment.

  Other configurations, operations, and effects in the present embodiment are the same as those in the second or third embodiment.

[Fifth Embodiment]
Next, an angle sensor system according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 14 is an explanatory diagram showing a schematic configuration of the angle sensor system according to the present embodiment. Similar to the first embodiment, the physical information generation unit 5 in the present embodiment is a magnetic field generation unit that generates a rotating magnetic field as physical information. FIG. 14 shows a magnet 7 in which one or more sets of N poles and S poles are alternately arranged in a ring shape as an example of the magnetic field generation unit. In the example shown in FIG. 14, the paper surface in FIG. 14 is the XY plane, and the direction perpendicular to the paper surface is the Z direction.

  The angle sensor 1 according to the present embodiment detects the direction of the rotating magnetic field generated from the outer periphery of the magnet 7. The relative position of the magnet 7 with respect to the angle sensor 1 changes so as to rotate about the central axis. This is realized, for example, by rotating the magnet 7 around a predetermined central axis parallel to the Z direction in conjunction with an operating body (not shown) that rotates. When the relative position of the magnet 7 with respect to the angle sensor 1 changes, the direction of the rotating magnetic field detected by the angle sensor 1 rotates about the central axis (Z direction). In the example shown in FIG. 14, the magnet 7 rotates in the clockwise direction, and the direction of the rotating magnetic field detected by the angle sensor 1 rotates in the counterclockwise direction.

  The configuration of the angle sensor 1 according to the present embodiment may be the same as any one of the first to fourth embodiments. The plurality of detection circuits included in the angle sensor 1 are arranged at the same position in the rotation direction of the magnet 7.

  Other configurations, operations, and effects in the present embodiment are the same as those in any of the first to fourth embodiments.

[Sixth Embodiment]
Next, an angle sensor system according to a sixth embodiment of the present invention will be described with reference to FIG. FIG. 15 is an explanatory diagram showing a schematic configuration of the angle sensor system according to the present embodiment. Similar to the first embodiment, the physical information generation unit 5 in the present embodiment is a magnetic field generation unit that generates a rotating magnetic field as physical information. FIG. 15 shows a magnet 8 in which a plurality of sets of N poles and S poles are alternately arranged in a straight line as an example of the magnetic field generator. In the example shown in FIG. 15, the paper surface in FIG. 15 is the XY plane, and the direction perpendicular to the paper surface is the Z direction. The N pole and S pole of the magnet 8 are arranged so as to be aligned in the X direction.

  The angle sensor 1 according to the present embodiment detects the direction of the rotating magnetic field generated from the outer periphery of the magnet 8. The relative position of the magnet 8 with respect to the angle sensor 1 changes linearly. This is realized by, for example, one of the angle sensor 1 and the magnet 8 moving linearly in the X direction in conjunction with an operating body (not shown). When the relative position of the magnet 8 with respect to the angle sensor 1 changes, the direction of the rotating magnetic field detected by the angle sensor 1 rotates around the Z direction.

  The configuration of the angle sensor 1 according to the present embodiment may be the same as any one of the first to fourth embodiments. The plurality of detection circuits included in the angle sensor 1 are arranged at the same position in the X direction.

  Other configurations, operations, and effects in the present embodiment are the same as those in any of the first to fourth embodiments.

  In addition, this invention is not limited to said each embodiment, A various change is possible. For example, the present invention can be applied not only to a magnetic angle sensor but also to an entire angle sensor and an angle sensor system including an optical angle sensor. In the case of an angle sensor system including an optical angle sensor and an optical scale, the physical information is optical information that varies depending on the relative position of the optical scale with respect to the angle sensor. In this case, the angle of the detection target is, for example, the angle when the relative position of the optical scale with respect to the angle sensor is expressed as an angle with one pitch of the optical scale being 360 °.

  DESCRIPTION OF SYMBOLS 1 ... Angle sensor, 2 ... Detection signal generation part, 3 ... Angle detection part, 4 ... State discrimination | determination apparatus, 5 ... Physical information generation part, 6 ... Magnet, 10 ... 1st detection circuit, 20 ... 2nd detection circuit , 30 ... third detection circuit, 31 ... conversion processing unit, 32 ... common correction processing unit, 33 ... non-common correction processing unit, 34 ... angle calculation unit, 41 ... determination value generation unit, 42 ... discrimination unit.

Claims (17)

A detection signal generation unit that generates a plurality of detection signals each having a corresponding relationship with the angle of the detection target;
An angle detection unit that generates an angle detection value having a correspondence relationship with the angle of the detection target based on the plurality of detection signals;
An angle sensor including a state determination device,
The state determination device includes a determination value generation unit that generates a determination value used for determining whether or not the angle sensor is in a predetermined state, and the angle sensor is in a predetermined state based on the determination value. And a determination unit for determining whether or not
The angle detection unit converts a plurality of pre-correction signals corresponding to the plurality of detection signals into a plurality of common post-correction signals used for generating the angle detection value and the determination value. A common correction processing unit that performs processing and the plurality of common corrected signals are used for calculation for generating the angle detection value, but are not used for generation of the determination value. And a non-common correction processing unit that performs non-common correction processing for conversion into a second angle calculation signal, and an angle calculation unit that calculates the detected angle value using the first and second angle calculation signals. Including
The determination value generation unit generates the determination value based on the plurality of common corrected signals,
In the common correction process, an angle error generated in the angle detection value is reduced as compared with a case where the angle detection value is generated using the plurality of pre-correction signals without performing the common correction process, and the common correction process is performed. Compared to the case where the determination value is generated using the plurality of pre-correction signals without performing correction processing, the plurality of the variation of the determination value according to the angle of the detection target is reduced. A process of converting a signal before correction into the plurality of signals after common correction;
The non-common correction process is to reduce an angle error generated in the angle detection value compared to a case where the angle detection value is generated using the plurality of common corrected signals without the non-common correction process. An angle sensor characterized by the following processing.
  The angle sensor according to claim 1, wherein the predetermined state is a state in which the angle sensor has not failed. The plurality of common corrected signals are first and second common corrected signals,
When the angle of the detection target changes at a predetermined cycle, each of the first and second common corrected signals includes an ideal component that periodically changes to draw an ideal sine curve,
The phase difference between the ideal component of the first common corrected signal and the ideal component of the second common corrected signal is 90 °,
The amplitudes of the first common corrected signal and the second common corrected signal are equal,
The determination value generation unit generates the determination value by performing an operation including obtaining a sum of a square of the first common corrected signal and a square of the second common corrected signal. The angle sensor according to claim 1 or 2. The angle of the detection target is an angle formed by the direction of the rotating magnetic field at the reference position with respect to the reference direction,
The detection signal generation unit includes a plurality of detection circuits that generate the plurality of detection signals,
4. The angle sensor according to claim 1, wherein each of the plurality of detection circuits includes at least one magnetic detection element that detects the rotating magnetic field. 5. The at least one magnetic sensing element includes a plurality of magnetoresistive effect elements connected in series,
Each of the plurality of magnetoresistive elements includes a magnetization fixed layer whose magnetization direction is fixed, a free layer whose magnetization direction changes according to the direction of the rotating magnetic field, and between the magnetization fixed layer and the free layer The angle sensor according to claim 4, further comprising a nonmagnetic layer disposed on the surface.   The angle sensor according to claim 1, wherein the common correction process includes a process of correcting offsets of the plurality of pre-correction signals.   The angle sensor according to claim 1, wherein the common correction process includes a process of normalizing amplitudes of the plurality of pre-correction signals. The plurality of pre-correction signals are first and second pre-correction signals,
The plurality of common corrected signals are first and second common corrected signals,
When the angle of the detection target changes at a predetermined cycle, the first and second pre-correction signals and the first and second common post-correction signals each cycle so as to draw an ideal sine curve. Contains ideal components that change over time,
The common correction processing includes the ideal component of the first common post-correction signal regardless of the phase difference between the ideal component of the first pre-correction signal and the ideal component of the second pre-correction signal. And a phase difference of the ideal component of the second common corrected signal is set to 90 °, and the amplitudes of the first common corrected signal and the second common corrected signal are made equal to each other. An angle sensor according to any one of claims 1 to 7. When the angle of the detection target changes at a predetermined cycle, each of the plurality of detection signals includes an ideal component that periodically changes to draw an ideal sine curve and a third harmonic with respect to the ideal component. Corresponding error components,
The angle detection unit further includes a conversion processing unit that performs conversion processing for converting the plurality of detection signals into the plurality of pre-correction signals in which the error component is reduced compared to each of the plurality of detection signals. An angle sensor according to any one of claims 1 to 8, wherein When the angle of the detection target changes at a predetermined cycle, each of the plurality of pre-correction signals has an ideal component that periodically changes so as to draw an ideal sine curve, and a third harmonic with respect to the ideal component. And an error component corresponding to
9. The process according to claim 1, wherein the common correction process includes a process of reducing the error component included in each of the plurality of common corrected signals as compared with each of the plurality of pre-correction signals. An angle sensor according to claim 1. The angular error reduced by the non-common correction process includes at least one of a first angular error component and a second angular error component;
When the angle of the detection target changes at a predetermined cycle, the first angle error component changes at a cycle equal to the predetermined cycle, and the second angle error component is 1 of the predetermined cycle. The angle sensor according to any one of claims 1 to 10, wherein the angle sensor changes at a period of / 2. The angular error reduced by the non-common correction process includes a third angular error component,
12. The third angle error component changes in a quarter of the predetermined period when the angle of the detection target changes in a predetermined period . angle sensor according to. An angle sensor according to claim 1;
A physical information generating unit that generates physical information having a correspondence relationship with the angle of the detection target;
The angle sensor system, wherein the detection signal generation unit detects the physical information and generates the plurality of detection signals. The physical information generating unit is a magnetic field generating unit that generates a rotating magnetic field as the physical information,
14. The angle sensor system according to claim 13, wherein the angle of the detection target is an angle formed by a direction of the rotating magnetic field at a reference position with respect to a reference direction. The physical information generating unit is configured so that the angle of the detection target is changed, the angle sensor system according to claim 13 or 14, wherein the relative position with respect to the angle sensor is changed. The angle sensor system according to claim 15, wherein a relative position of the physical information generation unit with respect to the angle sensor changes so as to rotate about a central axis. The angle sensor system according to claim 15, wherein a relative position of the physical information generation unit with respect to the angle sensor changes linearly.

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