Magnetic sensors and sensor systems

Abstract

The purpose of the present disclosure is to reduce the harmonic components included in the output signal. The magnetic sensor (1) includes a detection magnetoresistive element (11) and a cancellation magnetoresistive element (12). The inclination angle formed by the magnetic sensitivity direction of the cancellation magnetoresistive element (12) relative to the magnetic sensitivity direction of the detection magnetoresistive element (11) is within a predetermined range. The predetermined range is defined by reference to n×α / 3 or n×α / 3+α / 2, where α is the rotation angle of the rotor corresponding to one cycle of the first harmonic included in the output signal (V1, V2) of the detection magnetoresistive element (11), and n is a natural number equal to or greater than 1.

Description

Technical Field

[0001] The present disclosure relates generally to magnetic sensors and sensor systems, and more particularly to magnetic sensors and sensor systems including magnetoresistive elements. Background Art

[0002] Patent document 1 discloses a rotation angle sensor (sensor system) using two magnetic sensors. The rotation angle sensor of patent document 1 includes two magnetic sensors and a signal processing IC part (processing circuit). On a printed wiring board, the two magnetic sensors are arranged at corresponding positions to form an angle θ of 90 degrees between the two. In addition, a magnet fixed to the rotor is arranged on the printed wiring board to face the two magnetic sensors.

[0003] In the rotation angle sensor of Patent Document 1, a magnetic field generated by a magnet rotating together with a rotor is detected by two magnetic sensors. Therefore, a sine wave as an X component is detected by one magnetic sensor, and a cosine wave as a Y component is detected by the other magnetic sensor.

[0004] Reference List

[0005] Patent Literature

[0006] Patent Document 1: JP 2007-155668 A Summary of the invention

[0007] The rotation angle sensor of Patent Document 1 may cause erroneous detection due to the presence of harmonic components in the output signal of the magnetic sensor. Therefore, there is a growing demand for reducing the harmonic components of the output signal.

[0008] It is therefore an object of the present disclosure to provide a magnetic sensor and a sensor system having the ability to reduce harmonic components included in an output signal.

[0009] A magnetic sensor according to one aspect of the present disclosure is used to detect the rotation angle of a rotor. The magnetic sensor includes a detection magnetoresistive element and a cancellation magnetoresistive element. The inclination angle formed by the magnetic sensitivity direction of the cancellation magnetoresistive element relative to the magnetic sensitivity direction of the detection magnetoresistive element is within a predetermined range. The predetermined range is defined by reference to n×α / 3 or n×α / 3+α / 2, where α is a rotation angle corresponding to one period of a first harmonic included in an output signal of the detection magnetoresistive element, and n is a natural number equal to or greater than 1.

[0010] According to another aspect of the present disclosure, a sensor system includes: the magnetic sensor described above; and a processing circuit. The processing circuit performs signal processing on an output signal of the magnetic sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1is a block diagram showing a configuration of a magnetic sensor and a sensor system according to an exemplary embodiment;

[0012] Figure 2 is a plan view showing an exemplary arrangement of magnetoresistive elements forming a magnetic sensor;

[0013] Figure 3A and Figure 3B shows the waveforms of a pair of output signals of a detection magnetoresistive element as a constituent element of a magnetic sensor;

[0014] Figure 4A and Figure 4B shows waveforms of another pair of output signals of a detection magnetoresistive element as a constituent element of the magnetic sensor;

[0015] Figure 5A and Figure 5B shows the waveforms of a pair of output signals of a cancelling magnetoresistive element as a constituent element of the magnetic sensor;

[0016] Fig. 6A and Figure 6B shows waveforms of another pair of output signals of a cancelling magnetoresistive element as a constituent element of the magnetic sensor;

[0017] Fig. 7A and Figure 7B shows the waveform of a signal obtained after performing a differential operation on a pair of output signals of a detection magnetoresistive element and a cancel magnetoresistive element which are constituent elements of the magnetic sensor;

[0018] Fig. 8A and Figure 8B shows the waveform of a signal obtained after performing a differential operation on another pair of output signals of a detection magnetoresistive element and a cancel magnetoresistive element which are constituent elements of the magnetic sensor;

[0019] Fig. 9 is a block diagram of a processing circuit as a constituent element of a sensor system according to a first variation of the exemplary embodiment; and

[0020] Fig.10 is a plan view showing an exemplary arrangement of magnetoresistive elements forming a magnetic sensor according to a second modification of the exemplary embodiment. DETAILED DESCRIPTION

[0021] [Example]

[0022] (1) Overview

[0023] Will refer to Figure 1 and Figure 2 An overview of a magnetic sensor 1 and a sensor system 10 including the magnetic sensor 1 according to an exemplary embodiment is described.

[0024] For example, the magnetic sensor 1 and the sensor system 10 according to this embodiment can be used to detect a rotor 200 such as a steering shaft for a vehicle (see Figure 2 ). Specifically, for example, as the magnetic field generated by the magnet coupled to the rotor 200 via the transmission device changes its strength, the resistance values ​​of the first detection magnetoresistors 131 to 134 and the second detection magnetoresistors 141 to 144 to be described later also change. Then, the rotation angle of the rotor 200 can be detected by detecting the change in the resistance values ​​of the first detection magnetoresistors 131 to 134 and the second detection magnetoresistors 141 to 144.

[0025] The magnetic sensor 1 according to this embodiment includes the following Figure 1 The detection magnetoresistive element 11 and the cancellation magnetoresistive element 12 are shown. In this embodiment, each of the detection magnetoresistive element 11 and the cancellation magnetoresistive element 12 may be implemented as, for example, an anisotropic magnetoresistive (AMR) element.

[0026] The detection magnetoresistive element 11 includes a first detection bridge circuit 13 and a second detection bridge circuit 14. The first detection bridge circuit 13 outputs a cosine wave signal. The second detection bridge circuit 14 outputs a sine wave signal. The cancellation magnetoresistive element 12 includes a first cancellation bridge circuit 15 and a second cancellation bridge circuit 16. The first cancellation bridge circuit 15 outputs a cosine wave signal. The second cancellation bridge circuit 16 outputs a sine wave signal.

[0027] The first detection bridge circuit 13 includes four first detection magnetoresistive patterns 135 to 138. The second detection bridge circuit 14 includes four second detection magnetoresistive patterns 145 to 148. The first cancellation bridge circuit 15 includes four first cancellation magnetoresistive patterns 155 to 158. The second cancellation bridge circuit 16 includes four second cancellation magnetoresistive patterns 165 to 168.

[0028] The inclination angle β1 formed by the magnetic sensitivity direction M2 of the canceling magnetoresistive element 12 relative to the magnetic sensitivity direction M1 of the detecting magnetoresistive element 11 falls within a predetermined range. The predetermined range is defined by reference to n×α / 3 or n×α / 3+α / 2, where α is the first harmonic W11, W21 included in the output signals V1, V2 of the detecting magnetoresistive element 11 (see Figure 3A and Figure 4A), and n is a natural number equal to or greater than 1. In this embodiment, each of the detection magnetoresistive element 11 and the cancellation magnetoresistive element 12 is implemented as an AMR. Therefore, the rotation angle α corresponding to one cycle of the first harmonic W11, W21 of the rotor 200 is 180 degrees. In addition, in this embodiment, the reference of the predetermined range can be, for example, 60 degrees. As used herein, "magnetic sensitive direction" refers to the direction in which the reaction (sensitivity) to the magnetic flux becomes the largest. For example, if each magnetoresistive pattern has a Figure 2 As shown in the meandering shape, the direction in which the meandering shape extends is the magnetic sensitivity direction.

[0029] The sensor system 10 according to this embodiment includes the magnetic sensor 1 described above and Figure 1 The processing circuit 2 shown in FIG. 2 performs signal processing on the output signals V1 , V2 , V3 , V4 of the magnetic sensor 1 .

[0030] In the magnetic sensor 1 and the sensor system 10 according to this embodiment, the inclination angle β1 formed by the magnetic sensitivity direction M2 of the cancel magnetoresistive element 12 relative to the magnetic sensitivity direction M1 of the detection magnetoresistive element 11 falls within a predetermined range. Therefore, performing a differential operation between the output signals V1, V2 of the detection magnetoresistive element 11 and the output signals V3, V4 of the cancel magnetoresistive element 12 can reduce the harmonic components included in the output signals V1, V2. In this case, the output signals V1, V2 include the third harmonic, the fourth harmonic, the fifth harmonic, etc. as harmonic components. In addition, the influence caused by the third harmonic is the most significant, so the magnetic sensor 1 and the sensor system 10 to be described below remove the third harmonic components included in the output signals V1, V2.

[0031] (2) Configuration

[0032] Next, refer to Figure 1 and Figure 2 The configuration of the sensor system 10 according to this embodiment is described. The sensor system 10 according to this embodiment includes Figure 1 The magnetic sensor 1 and the processing circuit 2 are shown.

[0033] (2.1) Magnetic sensor

[0034] The magnetic sensor 1 includes: Figure 1 The detection magnetoresistance element 11 and the cancellation magnetoresistance element 12 are shown. The detection magnetoresistance element 11 is an element for detecting the rotation angle of the rotor 200. The cancellation magnetoresistance element 12 is an element for removing the harmonic components included in the output signals (first output signals) V1 and V2 of the detection magnetoresistance element 11. In this embodiment, the harmonic components may be, for example, the third harmonic components included in the output signals V1 and V2.

[0035] The detection magnetoresistive element 11 includes a first detection bridge circuit 13 and a second detection bridge circuit 14 .

[0036] For example, the first detection bridge circuit 13 may be implemented as a plurality of (eg, Figure 1 4 in the example shown) is a full-bridge circuit consisting of the first detection magnetoresistors 131 to 134. Specifically, the first series circuit is formed by connecting the respective first ends of the first detection magnetoresistors 131, 133 together, and the second series circuit is formed by connecting the respective first ends of the first detection magnetoresistors 132, 134 together. Then, the first series circuit and the second series circuit are electrically connected in parallel between the reference potential Vc and the ground GND. In other words, the respective second ends of the first detection magnetoresistors 131, 132 are electrically connected to the reference potential Vc, and the respective second ends of the first detection magnetoresistors 133, 134 are electrically connected to the ground GND. In this case, for example, each of the first detection magnetoresistors 131 to 134 has a resistance value that changes with changes in the magnetic field generated by the magnet coupled to the rotor 200 via the transmission device. Furthermore, in this first detection bridge circuit 13, two cosine wave signals having phases different from each other by 180 degrees are outputted from the connection node between the first detection magnetoresistors 131, 133 and the connection node between the first detection magnetoresistors 132, 134, respectively. Specifically, in this first detection bridge circuit 13, a +cos signal (cosine wave signal) is outputted from the connection node between the first detection magnetoresistors 131, 133, and a –cos signal (cosine wave signal) is outputted from the connection node between the first detection magnetoresistors 132, 134.

[0037] For example, the second detection bridge circuit 14 may be implemented as a plurality of (eg, Figure 14 in the example shown) second detection magnetoresistors 141 to 144 are formed into a full bridge circuit. Specifically, the first series circuit is formed by connecting the respective first ends of the second detection magnetoresistors 141 and 143 together, and the second series circuit is formed by connecting the respective first ends of the second detection magnetoresistors 142 and 144 together. Then, the first series circuit and the second series circuit are electrically connected in parallel between the reference potential Vc and the ground GND. In other words, the respective second ends of the second detection magnetoresistors 141 and 142 are electrically connected to the reference potential Vc, and the respective second ends of the second detection magnetoresistors 143 and 144 are electrically connected to the ground GND. The second detection bridge circuit 14 is arranged to limit a rotation angle of 45 degrees relative to the first detection bridge circuit 13. Therefore, in this second detection bridge circuit 14, two sinusoidal wave signals with a phase difference of 180 degrees from each other are output from the connection node between the second detection magnetoresistors 141 and 143 and the connection node between the second detection magnetoresistors 142 and 144, respectively. Specifically, in this second detection bridge circuit 14, a +sin signal (sine wave signal) is output from a connection node between the second detection magnetoresistors 141, 143, and a -sin signal (sine wave signal) is output from a connection node between the second detection magnetoresistors 142, 144. In other words, the detection magnetoresistance element 11 includes a first detection bridge circuit 13 for outputting a cosine wave signal and a second detection bridge circuit 14 for outputting a sine wave signal.

[0038] Meanwhile, the cancel magnetoresistive element 12 includes a first cancel bridge circuit 15 and a second cancel bridge circuit 16 .

[0039] For example, the first offset bridge circuit 15 may be implemented as a plurality of (eg, Figure 14) in the example shown in the figure, a full bridge circuit consisting of the first offset magnetic resistors 151 to 154. Specifically, the first series circuit is formed by connecting the respective first ends of the first offset magnetic resistors 151 and 153 together, and the second series circuit is formed by connecting the respective first ends of the first offset magnetic resistors 152 and 154 together. Then, the first series circuit and the second series circuit are electrically connected in parallel between the reference potential Vc and the ground GND. In other words, the respective second ends of the first offset magnetic resistors 151 and 152 are electrically connected to the reference potential Vc, and the respective second ends of the first offset magnetic resistors 153 and 154 are electrically connected to the ground GND. The first offset bridge circuit 15 is arranged to limit a rotation angle of 60 degrees relative to the first detection bridge circuit 13. Therefore, in this first offset bridge circuit 15, two cosine wave signals with a phase difference of 180 degrees from each other are output from the connection node between the first offset magnetic resistors 151 and 153 and the connection node between the first offset magnetic resistors 152 and 154, respectively. Specifically, in this first cancellation bridge circuit 15 , a +cos signal is output from a connection node between the first cancellation magnetic resistors 151 , 153 , and a −cos signal is output from a connection node between the first cancellation magnetic resistors 152 , 154 .

[0040] For example, the second compensation bridge circuit 16 may be implemented as a plurality of (eg, Figure 14) in the example shown in the figure, a full bridge circuit consisting of second compensation magnetic resistors 161 to 164. Specifically, the first series circuit is formed by connecting the respective first ends of the second compensation magnetic resistors 161, 163 together, and the second series circuit is formed by connecting the respective first ends of the second compensation magnetic resistors 162, 164 together. Then, the first series circuit and the second series circuit are electrically connected in parallel between the reference potential Vc and the ground GND. In other words, the respective second ends of the second compensation magnetic resistors 161, 162 are electrically connected to the reference potential Vc, and the respective second ends of the second compensation magnetic resistors 163, 164 are electrically connected to the ground GND. The second compensation bridge circuit 16 is arranged to limit a rotation angle of 60 degrees relative to the second detection bridge circuit 14. In addition, the second compensation bridge circuit 16 is arranged to limit a rotation angle of 45 degrees relative to the first compensation bridge circuit 15. Therefore, in this second cancellation bridge circuit 16, two sinusoidal wave signals that are 180 degrees out of phase with each other are output from the connection node between the second cancellation magnetic resistors 161, 163 and the connection node between the second cancellation magnetic resistors 162, 164, respectively. Specifically, in this second cancellation bridge circuit 16, a +sin signal is output from the connection node between the second cancellation magnetic resistors 161, 163, and a -sin signal is output from the connection node between the second cancellation magnetic resistors 162, 164. In other words, the cancellation magnetic resistance element 12 includes a first cancellation bridge circuit 15 for outputting a cosine wave signal and a second cancellation bridge circuit 16 for outputting a sine wave signal.

[0041] Figure 2 1 is a plan view showing an exemplary arrangement of the detection magnetoresistive element 11 and the cancellation magnetoresistive element 12 forming a part of the magnetic sensor 1 according to this embodiment. The first detection magnetoresistive elements 131 to 134 forming a part of the detection magnetoresistive element 11 respectively have first detection magnetoresistive patterns 135 to 138 mounted on one surface of the board 100. The second detection magnetoresistive elements 141 to 144 forming a part of the detection magnetoresistive element 11 respectively have second detection magnetoresistive patterns 145 to 148 mounted on one surface of the board 100. Meanwhile, the first cancellation magnetoresistive elements 151 to 154 forming a part of the cancellation magnetoresistive element 12 respectively have first detection magnetoresistive patterns 155 to 158 mounted on one surface of the board 100. The second cancellation magnetoresistive elements 161 to 164 forming a part of the cancellation magnetoresistive element 12 respectively have second cancellation magnetoresistive patterns 165 to 168 mounted on one surface of the board 100.

[0042] Each of the first detection magnetoresistance patterns 135 to 138 and the second detection magnetoresistance patterns 145 to 148 may be configured as a metal pattern containing, for example, an iron-nickel alloy. Each of the first detection magnetoresistance patterns 135 to 138 and the second detection magnetoresistance patterns 145 to 148 may have, for example, a meandering shape. As used herein, a "meandering shape" refers to a shape that includes a plurality of straight line portions arranged in one direction, and in which each first end or each second end of each pair of adjacent straight line portions is alternately connected. The magnetically sensitive direction of each of the first detection magnetoresistance patterns 135 to 138 and the second detection magnetoresistance patterns 145 to 148 is parallel to the direction in which a plurality of straight line portions forming a magnetoresistance pattern are arranged side by side.

[0043] Each of the first offset magnetic resistance patterns 155 to 158 and the second offset magnetic resistance patterns 165 to 168 may be configured as a metal pattern including, for example, an iron-nickel alloy. Each of the first offset magnetic resistance patterns 155 to 158 and the second offset magnetic resistance patterns 165 to 168 may have, for example, a meandering shape. The magnetic sensitive direction of each of the first offset magnetic resistance patterns 155 to 158 and the second offset magnetic resistance patterns 165 to 168 is parallel to the direction in which a plurality of straight line portions forming the magnetic resistance pattern are arranged side by side.

[0044] The first detection magnetoresistive patterns 135 to 138 and the second detection magnetoresistive patterns 145 to 148 are arranged on one surface of the board 100 along a circumference C1 of a circle whose center is as shown in FIG. Figure 2 The point P1 shown as the rotation center of the rotor 200 is defined. On the other hand, the first and second offset reluctance patterns 155 to 158 and 165 to 168 are arranged on one surface of the plate 100 along the circumference C1 of a circle whose center is defined as shown in FIG. Figure 2 In other words, the first detection bridge circuit 13, the second detection bridge circuit 14, the first cancellation bridge circuit 15 and the second cancellation bridge circuit 16 are arranged along the circumference C1 of the same circle.

[0045] The four first detection magnetoresistive patterns 135 to 138 forming the first detection bridge circuit 13 are arranged along the circumference C1. Specifically, each of the first detection magnetoresistive patterns 136 and 137 is arranged so that its magnetic sensitivity direction forms an inclination angle of 90 degrees with respect to the magnetic sensitivity direction of the first detection magnetoresistive pattern 135. At the same time, the first detection magnetoresistive pattern 138 is arranged so that its magnetic sensitivity direction is aligned with the magnetic sensitivity direction of the first detection magnetoresistive pattern 135.

[0046] The four second detection magnetoresistance patterns 145 to 148 forming the second detection bridge circuit 14 are arranged along the circumference C1. Specifically, the second detection magnetoresistance pattern 145 is arranged so that its magnetic sensitivity direction forms an inclination of 45 degrees relative to the magnetic sensitivity direction of the first detection magnetoresistance pattern 135. The second detection magnetoresistance pattern 146 is arranged so that its magnetic sensitivity direction forms an inclination of 45 degrees relative to the magnetic sensitivity direction of the first detection magnetoresistance pattern 136. The second detection magnetoresistance pattern 147 is arranged so that its magnetic sensitivity direction forms an inclination of 45 degrees relative to the magnetic sensitivity direction of the first detection magnetoresistance pattern 137. The second detection magnetoresistance pattern 148 is arranged so that its magnetic sensitivity direction forms an inclination of 45 degrees relative to the magnetic sensitivity direction of the first detection magnetoresistance pattern 138. Therefore, the magnetic sensitivity direction of each of the second detection magnetoresistance patterns 146 and 147 defines an inclination of 90 degrees relative to the magnetic sensitivity direction of the second detection magnetoresistance pattern 145. At the same time, the magnetically sensitive direction of the second detecting magnetoresistive pattern 148 is aligned with the magnetically sensitive direction of the second detecting magnetoresistive pattern 145 .

[0047] The four first offset magnetoresistive patterns 155 to 158 forming the first offset bridge circuit 15 are arranged along the circumference C1. Specifically, the first offset magnetoresistive pattern 155 is arranged so that its magnetic sensitivity direction forms an inclination of 60 degrees relative to the magnetic sensitivity direction of the first detection magnetoresistive pattern 135. The first offset magnetoresistive pattern 156 is arranged so that its magnetic sensitivity direction forms an inclination of 60 degrees relative to the magnetic sensitivity direction of the first detection magnetoresistive pattern 136. The first offset magnetoresistive pattern 157 is arranged so that its magnetic sensitivity direction forms an inclination of 60 degrees relative to the magnetic sensitivity direction of the first detection magnetoresistive pattern 137. The first offset magnetoresistive pattern 158 is arranged so that its magnetic sensitivity direction forms an inclination of 60 degrees relative to the magnetic sensitivity direction of the first detection magnetoresistive pattern 138. Therefore, the magnetic sensitivity direction of each of the first offset magnetoresistive patterns 156 and 157 defines an inclination of 90 degrees relative to the magnetic sensitivity direction of the first offset magnetoresistive pattern 155. At the same time, the magnetically sensitive direction of the first offset magnetic resistance pattern 158 is aligned with the magnetically sensitive direction of the first offset magnetic resistance pattern 155 .

[0048] The four second offset magnetoresistive patterns 165 to 168 forming the second offset bridge circuit 16 are arranged along the circumference C1. Specifically, the second offset magnetoresistive pattern 165 is arranged so that its magnetic sensitivity direction forms an inclination of 60 degrees relative to the magnetic sensitivity direction of the second detection magnetoresistive pattern 145. The second offset magnetoresistive pattern 166 is arranged so that its magnetic sensitivity direction forms an inclination of 60 degrees relative to the magnetic sensitivity direction of the second detection magnetoresistive pattern 146. The second offset magnetoresistive pattern 167 is arranged so that its magnetic sensitivity direction forms an inclination of 60 degrees relative to the magnetic sensitivity direction of the second detection magnetoresistive pattern 147. The second offset magnetoresistive pattern 168 is arranged so that its magnetic sensitivity direction forms an inclination of 60 degrees relative to the magnetic sensitivity direction of the second detection magnetoresistive pattern 148. Therefore, the magnetic sensitivity direction of each of the second offset magnetoresistive patterns 166 and 167 defines an inclination of 90 degrees relative to the magnetic sensitivity direction of the second offset magnetoresistive pattern 165. At the same time, the magneto-sensitive direction of the second offset magneto-resistance pattern 168 is aligned with the magneto-sensitive direction of the second offset magneto-resistance pattern 165 .

[0049] In this embodiment, the magnetic sensitive direction of the first detection bridge circuit 13 composed of the four first detection magnetoresistive patterns 135 to 138 is assumed to be, for example, the magnetic sensitive direction M1 of the first detection magnetoresistive pattern 135. In addition, the magnetic sensitive direction of the second detection bridge circuit 14 composed of the four second detection magnetoresistive patterns 145 to 148 is assumed to be, for example, the magnetic sensitive direction of the second detection magnetoresistive pattern 145. In addition, the magnetic sensitive direction of the detection magnetoresistive element 11 composed of the first detection bridge circuit 13 and the second detection bridge circuit 14 is assumed to be, for example, the magnetic sensitive direction M1 of the first detection magnetoresistive pattern 135.

[0050] On the other hand, the magnetic sensitive direction of the first cancellation bridge circuit 15 composed of the four first cancellation magnetoresistive patterns 155 to 158 is assumed to be, for example, the magnetic sensitive direction M2 of the first cancellation magnetoresistive pattern 155. In addition, the magnetic sensitive direction of the second cancellation bridge circuit 16 composed of the four second cancellation magnetoresistive patterns 165 to 168 is assumed to be, for example, the magnetic sensitive direction of the second cancellation magnetoresistive pattern 165. In addition, the magnetic sensitive direction of the cancellation magnetoresistive element 12 composed of the first cancellation bridge circuit 15 and the second cancellation bridge circuit 16 is assumed to be, for example, the magnetic sensitive direction M2 of the first cancellation magnetoresistive pattern 155. Therefore, the inclination angle β1 formed by the magnetic sensitive direction M2 of the cancellation magnetoresistive element 12 with respect to the magnetic sensitive direction M1 of the detection magnetoresistive element 11 is the inclination angle β1 formed by the magnetic sensitive direction M2 of the first cancellation magnetoresistive pattern 155 with respect to the magnetic sensitive direction M1 of the first detection magnetoresistive pattern 135, and may be, for example, 60 degrees. It is to be noted that the inclination angle β1 is not necessarily 60 degrees, but may fall within a predetermined range including 60 degrees as a reference angle. Specifically, the predetermined range is suitably a range of 60 degrees ± 10 degrees, and more suitably a range of 60 degrees ± 5 degrees.

[0051] (2.2) Processing circuit

[0052] The processing circuit 2 performs signal processing on the output signal of the magnetic sensor 1. Figure 1 As shown, the processing circuit 2 includes multiple (for example, Figure 1 6 in the example shown) differential amplifiers 21 to 26, a plurality of (eg, Figure 1 2 in the example shown) A / D converters 27, 28 and an arithmetic unit 29.

[0053] The differential amplifier 21 includes a first input terminal, a second input terminal and an output terminal. The first input terminal is a non-inverting input terminal and is electrically connected to a connection node between the first detection magnetic resistors 131 and 133 of the first detection bridge circuit 13. The second input terminal is an inverting input terminal and is electrically connected to a connection node between the first detection magnetic resistors 132 and 134 of the first detection bridge circuit 13. The differential amplifier 21 differentially amplifies the +cos signal provided to its first input terminal and the -cos signal provided to its second input terminal, thereby generating a cos signal with doubled amplitude. The differential amplifier 21 outputs the cos signal thus generated through its output terminal (hereinafter referred to as "output signal V1").

[0054] The differential amplifier 22 includes a first input terminal, a second input terminal and an output terminal. The first input terminal is a non-inverting input terminal and is electrically connected to a connection node between the second detection magnetic resistors 141 and 143 of the second detection bridge circuit 14. The second input terminal is an inverting input terminal and is electrically connected to a connection node between the second detection magnetic resistors 142 and 144 of the second detection bridge circuit 14. The differential amplifier 22 differentially amplifies the +sin signal provided to its first input terminal and the –sin signal provided to its second input terminal, thereby generating a sin signal with doubled amplitude. The differential amplifier 22 outputs the sin signal thus generated through its output terminal (hereinafter referred to as "output signal V2").

[0055] The differential amplifier 23 includes a first input terminal, a second input terminal and an output terminal. The first input terminal is a non-inverting input terminal and is electrically connected to a connection node between the first offset magnetic resistors 151 and 153 of the first offset bridge circuit 15. The second input terminal is an inverting input terminal and is electrically connected to a connection node between the first offset magnetic resistors 152 and 154 of the first offset bridge circuit 15. The differential amplifier 23 differentially amplifies the +cos signal provided to its first input terminal and the -cos signal provided to its second input terminal, thereby generating a cos signal with doubled amplitude. The differential amplifier 23 outputs the cos signal thus generated through its output terminal (hereinafter referred to as "output signal V3").

[0056] The differential amplifier 24 includes a first input terminal, a second input terminal and an output terminal. The first input terminal is a non-inverting input terminal and is electrically connected to a connection node between the second offset magnetic resistors 161 and 163 of the second offset bridge circuit 16. The second input terminal is an inverting input terminal and is electrically connected to a connection node between the second offset magnetic resistors 162 and 164 of the second offset bridge circuit 16. The differential amplifier 24 differentially amplifies the +sin signal provided to its first input terminal and the –sin signal provided to its second input terminal, thereby generating a sin signal with doubled amplitude. The differential amplifier 24 outputs the sin signal thus generated through its output terminal (hereinafter referred to as "output signal V4").

[0057] The differential amplifier 25 includes a first input terminal, a second input terminal, and an output terminal. The first input terminal is a non-inverting input terminal, and receives the output signal V1 from the differential amplifier 21. The second input terminal is an inverting input terminal, and receives the output signal V3 from the differential amplifier 23. The differential amplifier 25 differentially amplifies the output signal V1 supplied to its first input terminal and the output signal V3 supplied to its second input terminal, thereby generating an output signal V5 and transmitting the output signal V5 through its output terminal.

[0058] The differential amplifier 26 includes a first input terminal, a second input terminal, and an output terminal. The first input terminal is a non-inverting input terminal, and receives the output signal V2 from the differential amplifier 22. The second input terminal is an inverting input terminal, and receives the output signal V4 from the differential amplifier 24. The differential amplifier 26 differentially amplifies the output signal V2 provided to its first input terminal and the output signal V4 provided to its second input terminal, thereby generating an output signal V6 and transmitting the output signal V6 through its output terminal.

[0059] The A / D converter 27 converts the analog signal (cos signal) supplied from the differential amplifier 25 into a digital signal at a predetermined sampling rate and outputs the digital signal obtained thereby.

[0060] The A / D converter 28 converts the analog signal (sin signal) supplied from the differential amplifier 26 into a digital signal at a predetermined sampling rate and outputs the digital signal obtained thereby.

[0061] The arithmetic unit 29 performs predetermined arithmetic processing on the two digital signals (i.e., the cos signal and the sin signal) respectively provided from the A / D converters 27 and 28. Specifically, the arithmetic unit 29 performs an inverse tangent operation on the two digital signals to obtain an angle. In this case, if the rotation angle of the rotor 200 is θ, the angle calculated by the inverse tangent operation is 2θ+30. Therefore, the arithmetic unit 29 can obtain the rotation angle θ by subtracting 30 from the calculated angle and then multiplying the result by 1 / 2.

[0062] The processing circuit 2 is implemented as, for example, a microcomputer including a processor and a memory. That is, the processing circuit 2 is implemented as a computer system including a processor and a memory. The computer system performs the functions of the processing circuit 2 by causing the processor to execute an appropriate program. The program may be stored in the memory in advance. Alternatively, the program may also be downloaded via a telecommunication line such as the Internet or distributed later after being stored in a non-transitory storage medium such as a memory card.

[0063] It should be noted that in the following description, the output signals V1, V2 of the differential amplifiers 21, 22 will sometimes be referred to as "the output signals V1, V2 of the detection magnetoresistive element 11" below. Similarly, the output signals V3, V4 of the differential amplifiers 23, 24 will be referred to as "the output signals V3, V4 of the cancellation magnetoresistive element 12" below.

[0064] (3) Difference operation

[0065] Next, refer to FIG. 3A to FIG. 8B How the processing circuit 2 performs the differential operation is described. Figure 3A The waveform of the first harmonic W11 of the output signal V1 of the differential amplifier 21 is shown. Figure 3B The waveform of the third harmonic W12 is shown. Figure 4A The waveform of the first harmonic W21 of the output signal V2 of the differential amplifier 22 is shown. Figure 4B The waveform of the third harmonic W22 is shown. Figure 5A The waveform of the first harmonic W31 of the output signal V3 of the differential amplifier 23 is shown. Figure 5B The waveform of the third harmonic W32 is shown. Fig. 6A The waveform of the first harmonic W41 of the output signal V4 of the differential amplifier 24 is shown. Figure 6B The waveform of the third harmonic W42 is shown. Fig. 7A The waveform of the first harmonic W51 after differential amplification of the output signals V1 and V3 is shown. Figure 7B The waveform of the third harmonic W52 is shown. Fig. 8A The waveform of the first harmonic W61 after differential amplification of the output signals V2 and V4 is shown. Figure 8B The waveform of the third harmonic W62 is shown.

[0066] The output signal V1 of the differential amplifier 21 is given by the following formula (1), where θ is the rotation angle of the rotor 200 and a is a coefficient:

[0067] V1=cos(2θ)+a×{-sin(6θ)} (1)

[0068] This formula (1) can be rewritten as the following formula (2):

[0069] V1=cos(2θ)+a×cos{3×2×(45-θ)} (2)

[0070] In formula (2), the first term is related to the first harmonic W11 (see Figure 3A ) corresponds to, and the second term corresponds to the third harmonic W12 (see Figure 3B ) corresponding to.

[0071] In addition, the output signal V2 of the differential amplifier 22 is given by the following formula (3):

[0072] V2=sin(2θ)+a×cos(6θ) (3)

[0073] This formula (3) can be rewritten as the following formula (4):

[0074] V2=cos{2×(θ-45)}+a×cos{3×2×(45-θ-45)} (4)

[0075] In formula (4), the first term is related to the first harmonic W21 (see Figure 4A ) corresponds to, and the second term corresponds to the third harmonic W22 (see Figure 4B ) corresponding to.

[0076] In addition, the output signal V3 of the differential amplifier 23 is given by the following formula (5):

[0077] V3=cos{2×(θ-60)}+a×cos{3×2×(45-θ-60)} (5)

[0078] In formula (5), the first term is related to the first harmonic W31 (see Figure 5A ) and the second term corresponds to the third harmonic W32 (see Figure 5B ) corresponding to.

[0079] In addition, the output signal V4 of the differential amplifier 23 is given by the following formula (6):

[0080] V4=cos{2×(θ-105)}+a×cos{3×2×(45-θ-105)} (6)

[0081] In formula (6), the first term is related to the first harmonic W41 (see Fig. 6A ) and the second term corresponds to the third harmonic W42 (see Figure 6B ) corresponding to.

[0082] The processing circuit 2 obtains the output signal V5 by causing the differential amplifier 25 to differentially amplify the output signals V1 and V3. In addition, the processing circuit 2 also obtains the output signal V6 by causing the differential amplifier 26 to differentially amplify the output signals V2 and V4. The output signal V5 is given by the following formula (7) and the output signal V6 is given by the following formula (8):

[0083]

[0084]

[0085] In this case, the amplitudes of the output signals V5 and V6 have been doubled by amplifying the amplitudes of the output signals V1 , V2 , V3 , and V4 .

[0086] like Fig. 7A and Figure 7B As shown, for the output signal V5 of the differential amplifier 25, only the first harmonic W51 remains, and the third harmonic W52 has become zero. Fig. 8A and Figure 8B As shown, for the output signal V5 of the differential amplifier 26, only the first harmonic W61 remains, and the third harmonic W62 has become zero. As can be seen, the magnetic sensor 1 and the sensor system 10 according to this embodiment can remove (or at least reduce) the third harmonic included in the output signals V1 and V2.

[0087] (4) Variant

[0088] Please note that the above embodiment is only one exemplary embodiment of the various embodiments of the present disclosure and should not be interpreted as limiting. On the contrary, the embodiment can be easily modified in various ways according to design choices or any other factors without departing from the scope of the present disclosure. Next, the variations of the embodiments will be listed one by one.

[0089] In the sensor system 10 according to the present disclosure, its processing circuit 2 includes, for example, a computer system. The computer system may include a processor and a memory as main hardware components. The functions of the sensor system 10 according to the present disclosure may be performed by causing the processor to execute a program stored in the memory of the computer system. The program may be pre-stored in the memory of the computer system. Alternatively, the program may also be downloaded via a telecommunications line or distributed later after being recorded in a non-temporary storage medium (e.g., a memory card, a CD, or a hard drive) readable by the computer system. The processor of the computer system may be implemented as a single or multiple electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). These electronic circuits may be integrated together on a single chip or distributed on multiple chips when appropriate. The multiple chips may be integrated together in a single device or distributed in multiple devices without restriction.

[0090] In addition, in the above-described embodiment, a plurality of components of the sensor system 10 are housed in a single housing. However, this is not a necessary configuration for the sensor system 10. Alternatively, these components of the sensor system 10 may be distributed in a plurality of different housings. Also alternatively, some functions of the sensor system 10 (e.g., the functions of the processing circuit 2) may also be implemented as a server system or a cloud computing system.

[0091] (4.1) First variant

[0092] In the above embodiment, the processing circuit 2 performs a differential operation on the first output signals V1 and V2 of the detection magnetoresistive element 11 and the second output signals V3 and V4 of the cancellation magnetoresistive element 12, and then amplifies the result of the differential operation. Fig. 9 As shown, the processing circuit 2A can amplify the first output signals V1, V2 and the second output signals V3, V4, and then perform a differential operation on the amplified first output signals V1, V2 and the second output signals V3, V4. Fig. 9 A sensor system 10 according to a first modification is described. The sensor system 10 according to the first modification has the same configuration as that of the sensor system 10 according to the above-described embodiment, except for the processing circuit 2A. Therefore, corresponding constituent elements of this first modification having the same functions as those of any constituent elements of the embodiment will be designated by the same reference numerals as those of the arbitrary constituent elements, and descriptions thereof will be omitted herein.

[0093] The sensor system 10 according to the first variant includes a magnetic sensor 1 and a processing circuit 2A. The processing circuit 2A includes: a plurality of (for example, Fig. 9 4 in the example shown in ) differential amplifiers 21 to 24; a plurality of (for example, Fig. 94 in the example shown in FIG. 4 ) A / D converters 27A, 27B, 28A, 28B; and an arithmetic unit 29A.

[0094] The differential amplifier 21 differentially amplifies the +cos signal and the –cos signal provided from the first detection bridge circuit 13 to provide an output signal V1. The differential amplifier 22 differentially amplifies the +sin signal and the –sin signal provided from the second detection bridge circuit 14 to provide an output signal V2. The differential amplifier 23 differentially amplifies the +cos signal and the –cos signal provided from the first cancellation bridge circuit 15 to provide an output signal V3. The differential amplifier 24 differentially amplifies the +sin signal and the –sin signal provided from the second cancellation bridge circuit 16 to provide an output signal V4.

[0095] The A / D converter 27A converts the output signal V1 of the differential amplifier 21 into a digital signal. The A / D converter 27B converts the output signal V2 of the differential amplifier 22 into a digital signal. The A / D converter 28A converts the output signal V3 of the differential amplifier 23 into a digital signal. The A / D converter 28B converts the output signal V4 of the differential amplifier 24 into a digital signal.

[0096] The arithmetic unit 29A performs a predetermined type of arithmetic processing on the 4 digital signals provided from the A / D converters 27A, 27B, 28A, and 28B. Specifically, the arithmetic unit 29A performs an inverse tangent operation on the 2 digital signals provided from the A / D converters 27A and 27B to obtain a first angle. In addition, the arithmetic unit 29A performs an inverse tangent operation on the 2 digital signals provided from the A / D converters 28A and 28B to obtain a second angle. In this case, each of the first angle and the second angle obtained by the inverse tangent operation does not include a third harmonic component and is converted into a fourth harmonic component. In addition, in this first variation, the third harmonic with a period of 60 degrees is converted into a fourth harmonic with a period of 45 degrees by the inverse tangent operation. Therefore, for the first angle, the arithmetic unit 29A obtains the third angle by multiplying the first angle by 1 / 2. For the second angle, the arithmetic unit 29A subtracts 22.5 from the second angle and then multiplies the remainder by 1 / 2 to obtain the fourth angle. Then, the arithmetic unit 29A can obtain the rotation angle θ by calculating the average value of the third angle and the fourth angle. At this time, the harmonic component can be removed (or at least reduced) by calculating the sum of the third angle and the fourth angle. That is, in the sensor system 10 according to the first variant, the processing circuit 2A amplifies the first output signal V1, V2 of the detection magnetoresistive element 11 and the second output signal V3, V4 of the offset magnetoresistive element 12, and then performs a differential operation on the amplified first output signal V1, V2 and the second output signal V3, V4. This allows the harmonic components (third harmonic components, etc.) included in the first output signals V1, V2 of the detection magnetoresistive element 11 to be reduced.

[0097] (4.2) Second variant

[0098] In the above embodiment, the first detection bridge circuit 13, the second detection bridge circuit 14, the first cancellation bridge circuit 15 and the second cancellation bridge circuit 16 are arranged along the circumference C1 of the same circle. Figure 2 Alternatively, the center P11 of the first detection bridge circuit 13A, the center P12 of the second detection bridge circuit 14A, the center P13 of the first cancellation bridge circuit 15A, and the center P14 of the second cancellation bridge circuit 16A may be offset from each other, as shown in FIG. Fig.10 As shown. Fig.10A sensor system 10 according to a second modification is described. The sensor system 10 according to the second modification has the same configuration as that of the sensor system 10 according to the embodiment, except for the arrangement of the first detection bridge circuit 13A, the second detection bridge circuit 14A, the first cancellation bridge circuit 15A, and the second cancellation bridge circuit 16A. Therefore, corresponding constituent elements of this second modification having the same functions as those of any constituent elements of the sensor system 10 according to the embodiment will be designated by the same reference numerals as those of the arbitrary constituent elements, and descriptions thereof will be omitted herein.

[0099] The sensor system 10 according to the second variation includes a magnetic sensor 1 and a processing circuit 2. The magnetic sensor 1 includes a detection magnetoresistive element 11 and a cancellation magnetoresistive element 12. The detection magnetoresistive element 11 includes a first detection bridge circuit 13A and a second detection bridge circuit 14A. The cancellation magnetoresistive element 12 includes a first cancellation bridge circuit 15A and a second cancellation bridge circuit 16A.

[0100] The first detection bridge circuit 13A has four first detection magnetic resistance patterns 135A to 138A. Fig.10 The second detection bridge circuit 14A has four second detection magnetic resistance patterns 145A to 148A, as shown in FIG. Fig.10 As shown. Four first detection magnetic resistance patterns 135A to 138A are mounted on one surface of the board 100A and have a square shape in a plan view. Four second detection magnetic resistance patterns 145A to 148A are mounted on one surface of the board 100A and have a square shape in a plan view.

[0101] The first offset bridge circuit 15A has four first offset magnetic resistance patterns 155A to 158A. Fig.10 The second compensation bridge circuit 16A has four second compensation magnetic resistance patterns 165A to 168A, as shown in FIG. Fig.10 As shown. Four first offset magnetic resistance patterns 155A to 158A are mounted on one surface of the board 100A and have a square shape in a plan view. Four second offset magnetic resistance patterns 165A to 168A are mounted on one surface of the board 100A and have a square shape in a plan view.

[0102] The first detection bridge circuit 13A, the second detection bridge circuit 14A, the first cancellation bridge circuit 15A, and the second cancellation bridge circuit 16A are arranged so that their respective centers P11, P12, P13, and P14 are offset from each other. As used herein, the "center of the bridge circuit" refers to the center of the magnetic resistance pattern in a plan view when the magnetic resistance pattern forming the bridge circuit is mounted on a board. For example, in the first detection bridge circuit 13A, Fig.10 The center P11 shown is the "center of the bridge circuit."

[0103] In the sensor system 10 according to the second modification, the center P11 of the first detection bridge circuit 13A, the center P12 of the second detection bridge circuit 14A, the center P13 of the first cancellation bridge circuit 15A, and the center P14 of the second cancellation bridge circuit 16A are offset from each other. This allows the bridge circuits 13A to 16A to be arranged on a single board 100A so that the magnetic resistance patterns 135A to 168A of each of these bridge circuits 13A to 16A are arranged together in their designated areas.

[0104] (4.3) Other variants

[0105] Next, other modifications of the above-described embodiment will be listed one by one.

[0106] In the above embodiment, both the detection magnetoresistive element 11 and the cancellation magnetoresistive element 12 are implemented as anisotropic magnetoresistive (AMR) elements. However, this is only an example and should not be construed as a limitation. Alternatively, one of the detection magnetoresistive element 11 or the cancellation magnetoresistive element 12 may be implemented as an anisotropic magnetoresistive element, and the other may be implemented as a tunneling magnetoresistive (TMR) element or a giant magnetoresistive (GMR) element. Also alternatively, both the detection magnetoresistive element 11 and the cancellation magnetoresistive element 12 may be implemented as tunneling magnetoresistive elements or giant magnetoresistive elements. Please note that if the detection magnetoresistive element 11 is implemented as a TMR element or a GMR element, then 2θ in formulas (1), (2), (3), (7) and (8) needs to be replaced by θ, 6θ in formulas (1) and (3) needs to be replaced by 3θ, and "2" in formulas (2) and (4) needs to be deleted. On the other hand, if the cancel magnetoresistive element 12 is implemented as a TMR element or a GMR element, "2" in equations (5) and (6) needs to be deleted. Furthermore, the arithmetic unit 29 is required to perform arithmetic processing of multiplying by 1 / 2.

[0107] In the above embodiment, the first detection magnetoresistance patterns 135 to 138, the second detection magnetoresistance patterns 145 to 148, the first offset magnetoresistance patterns 155 to 158, and the second offset magnetoresistance patterns 165 to 168 are all connected in full bridge. Alternatively, for example, the first detection magnetoresistance pattern and the second detection magnetoresistance pattern may be connected in full bridge, and the first offset magnetoresistance pattern and the second offset magnetoresistance pattern may be connected in half bridge, or vice versa. If the first detection magnetoresistance pattern and the second detection magnetoresistance pattern are connected in half bridge, the differential amplifiers 21 and 22 may be omitted. On the other hand, if the first offset magnetoresistance pattern and the second offset magnetoresistance pattern are connected in half bridge, the differential amplifiers 23 and 24 may be omitted.

[0108] In the above-described embodiment, the first detection magnetoresistance patterns 135 to 138, the second detection magnetoresistance patterns 145 to 148, the first offset magnetoresistance patterns 155 to 158, and the second offset magnetoresistance patterns 165 to 168 are mounted on a single board 100. Alternatively, the first detection magnetoresistance patterns 135 to 138, the second detection magnetoresistance patterns 145 to 148, the first offset magnetoresistance patterns 155 to 158, and the second offset magnetoresistance patterns 165 to 168 may be mounted on a plurality of different boards. For example, the first detection magnetoresistance patterns 135 to 138 and the second detection magnetoresistance patterns 145 to 148 may be mounted on a first board, and the first offset magnetoresistance patterns 155 to 158 and the second offset magnetoresistance patterns 165 to 168 may be mounted on a second board. In this case, the first board and the second board may be placed one above the other or arranged side by side laterally. Also alternatively, the first and second detection magnetoresistance patterns 135 to 138 and 145 to 148 may be mounted on one surface of the board, and the first and second cancellation magnetoresistance patterns 155 to 158 and 165 to 168 may be mounted on another surface of the board.

[0109] In the above embodiment, the inclination angle β1 formed by the magnetic sensitivity direction of the canceling magnetoresistive element 12 relative to the magnetic sensitivity direction of the detecting magnetoresistive element 11 is 60 degrees. However, the inclination angle β1 is not necessarily 60 degrees, but may also be a multiple of 60 degrees. In other words, the inclination angle β1 needs to satisfy n×α / 3, where α is the rotation angle of the rotor 200 corresponding to one cycle of the primary harmonic included in the output signals V1, V2 of the detecting magnetoresistive element 11, and n is a natural number equal to or greater than 1. For example, if the detecting magnetoresistive element 11 is implemented as an AMR element, α is 180 degrees. In this case, the inclination angle β1 may be a multiple of 60 degrees.

[0110] Alternatively, the inclination angle β1 formed by the magnetic sensitivity direction of the canceling magnetoresistive element 12 relative to the magnetic sensitivity direction of the detecting magnetoresistive element 11 may also be 30 degrees. In this case, the harmonic components included in the output signals V1 and V2 and the harmonic components included in the output signals V3 and V4 have opposite phases. Therefore, the processing circuit 2 needs to add the output signals V1 and V3 together and add the output signals V2 and V4 together. In addition, the inclination angle β1 is not necessarily 30 degrees, but only needs to satisfy n×α / 3+α / 2, where n is a natural number equal to or greater than 1.

[0111] (Summary)

[0112] As can be seen from the above description, the magnetic sensor (1) according to the first aspect is used to detect the rotation angle of the rotor (200). The magnetic sensor (1) includes a detection magnetoresistive element (11) and a cancellation magnetoresistive element (12). The inclination angle (β1) formed by the magnetic sensitivity direction (M2) of the cancellation magnetoresistive element (12) relative to the magnetic sensitivity direction (M1) of the detection magnetoresistive element (11) falls within a predetermined range. The predetermined range is defined by reference to n×α / 3 or n×α / 3+α / 2, where α is a rotation angle corresponding to one period of the first harmonic (W11, W21) included in the output signal (V1, V2) of the detection magnetoresistive element (11), and n is a natural number equal to or greater than 1.

[0113] This aspect can reduce the harmonic components included in the output signal (V1, V2) of the detection magnetoresistive element (11).

[0114] In the magnetic sensor (1) according to the second aspect which can be implemented in combination with the first aspect, each of the detection magnetoresistive element (11) and the cancellation magnetoresistive element (12) is an anisotropic magnetoresistive element.

[0115] This aspect can reduce the harmonic components included in the output signal (V1, V2) of the detection magnetoresistive element (11).

[0116] In the magnetic sensor (1) according to the third aspect which can be implemented in combination with the first aspect or the second aspect, the detection magnetoresistive element (11) has four detection magnetoresistive patterns (135 to 138, 145 to 148). The four detection magnetoresistive patterns (135 to 138, 145 to 148) are full-bridge connected.

[0117] This aspect can improve the detection accuracy of the magnetoresistive element (11).

[0118] In the magnetic sensor (1) according to the fourth aspect which can be implemented in combination with any one of the first to third aspects, the cancel magnetoresistive element (12) has four cancel magnetoresistive patterns (155 to 158, 165 to 168). The four cancel magnetoresistive patterns (155 to 158, 165 to 168) are full-bridge connected.

[0119] This aspect can improve the detection accuracy of the magnetoresistive element (11).

[0120] In the magnetic sensor (1) according to the fifth aspect which can be implemented in combination with any one of the first to fourth aspects, the magnetoresistive element (11) includes: a first detection bridge circuit (13A) for outputting a cosine wave signal; and a second detection bridge circuit (14A) for outputting a sine wave signal. The first detection bridge circuit (13A) and the second detection bridge circuit (14A) are arranged so that their respective centers (P11, P12) are offset from each other.

[0121] This aspect allows the first detection bridge circuit (13A) and the second detection bridge circuit (14A) to be arranged on the same plane so that each of the first detection bridge circuit (13A) and the second detection bridge circuit (14A) has a magnetoresistive pattern commonly arranged in a designated area.

[0122] In the magnetic sensor (1) according to the sixth aspect which can be implemented in combination with the fifth aspect, the cancel magnetoresistive element (12) includes: a first cancel bridge circuit (15A) for outputting a cosine wave signal; and a second cancel bridge circuit (16A) for outputting a sine wave signal. The first detection bridge circuit (13A), the second detection bridge circuit (14A), the first cancel bridge circuit (15A) and the second cancel bridge circuit (16A) are arranged so that their respective centers (P11, P12, P13, P14) are offset from each other.

[0123] This aspect allows the first detection bridge circuit (13A), the second detection bridge circuit (14A), the first cancellation bridge circuit (15A) and the second cancellation bridge circuit (16A) to be arranged on the same plane so that each of the first detection bridge circuit (13A), the second detection bridge circuit (14A), the first cancellation bridge circuit (15A) and the second cancellation bridge circuit (16A) has a magnetic resistance pattern arranged together in a designated area.

[0124] In the magnetic sensor (1) according to the seventh aspect which can be implemented in combination with any one of the first to fourth aspects, the magnetoresistive element (11) includes: a first detection bridge circuit (13) for outputting a cosine wave signal; and a second detection bridge circuit (14) for outputting a sine wave signal. The cancel magnetoresistive element (12) includes: a first cancel bridge circuit (15) for outputting a cosine wave signal; and a second cancel bridge circuit (16) for outputting a sine wave signal. The first detection bridge circuit (13), the second detection bridge circuit (14), the first cancel bridge circuit (15) and the second cancel bridge circuit (16) are arranged along the circumference (C1) of a circle.

[0125] This aspect can more effectively reduce the harmonic components included in the output signal (V1, V2) of the detection magnetoresistive element (11).

[0126] In the magnetic sensor (1) according to the eighth aspect which can be implemented in combination with any one of the first to seventh aspects, the detection magnetoresistive element (11) and the cancellation magnetoresistive element (12) are mounted on the same board (100, 100A).

[0127] This aspect allows more accurate arrangement of the detection magnetoresistive element (11) and the cancellation magnetoresistive element (12), compared to a case where the detection magnetoresistive element (11) and the cancellation magnetoresistive element (12) are mounted on two different boards.

[0128] A sensor system (10) according to a ninth aspect comprises: a magnetic sensor (1) according to any one of the first to eighth aspects; and a processing circuit (2, 2A). The processing circuit (2, 2A) performs signal processing on an output signal (V1, V2, V3, V4) of the magnetic sensor (1).

[0129] This aspect can reduce the harmonic components included in the output signal (V1, V2) of the detection magnetoresistive element (11).

[0130] In the sensor system (10) according to the tenth aspect which can be implemented in combination with the ninth aspect, the processing circuit (2) performs a differential operation on the first output signal (V1, V2) of the detection magnetoresistive element (11) and the second output signal (V3, V4) of the cancellation magnetoresistive element (12), and then amplifies the result of the differential operation.

[0131] This aspect can reduce the harmonic components included in the first output signal (V1, V2) of the detection magnetoresistive element (11).

[0132] In a sensor system (10) according to the eleventh aspect which can be implemented in combination with the ninth aspect, a processing circuit (2A) amplifies a first output signal (V1, V2) of a detection magnetoresistive element (11) and a second output signal (V3, V4) of a cancellation magnetoresistive element (12), and then performs a differential operation on the amplified first output signal (V1, V2) and the second output signal (V3, V4).

[0133] This aspect can reduce the harmonic components included in the first output signal (V1, V2) of the detection magnetoresistive element (11).

[0134] Note that the constituent elements according to the second aspect to the eighth aspect are not essential constituent elements for the magnetic sensor (1) but may be omitted where appropriate.

[0135] Note that the constituent elements according to the tenth aspect or the eleventh aspect are not essential constituent elements for the sensor system (10) but may be omitted as appropriate.

[0136] Reference numerals list

[0137] 1 Magnetic sensor

[0138] 11 Detection of magnetoresistive elements

[0139] 12. Offset magnetoresistive element

[0140] 13, 13A first detection bridge circuit

[0141] 135 to 138 detect the magnetic resistance pattern

[0142] 14, 14A second detection bridge circuit

[0143] 145 to 148 detect the magnetic resistance pattern

[0144] 15, 15A first offset bridge circuit

[0145] 155 to 158 offset magnetic resistance pattern

[0146] 16, 16A second offset bridge circuit

[0147] 155 to 158 offset magnetic resistance pattern

[0148] 100, 100A board

[0149] 2, 2A processing circuit

[0150] Circumference of C1 circle

[0151] M1 detects the magnetic sensitivity direction of the magnetoresistive element

[0152] M2 offsets the magnetic sensitivity direction of the magnetoresistive element

[0153] P11, P12, P13, P14 Center

[0154] V1, V2 output signal (first output signal)

[0155] V3, V4 output signal (second output signal)

[0156] W11, W21 first harmonic

[0157] β1 inclination angle.

Claims

1. A magnetic sensor for detecting a rotation angle of a rotor, the magnetic sensor comprising: Detecting magnetoresistive elements; as well as To cancel the magnetoresistive element, an inclination angle formed by the magneto-sensitive direction of the cancel magneto-resistance element with respect to the magneto-sensitive direction of the detection magneto-resistance element is within a predetermined range defined by reference to n×α / 3 or n×α / 3+α / 2, where α is a rotation angle corresponding to one cycle of a first harmonic included in an output signal of the detection magneto-resistance element, and n is a natural number equal to or greater than 1, The detection magnetoresistive element comprises: A first detection bridge circuit is configured to output a cosine wave signal; and The second detection bridge circuit is configured to output a sine wave signal, The magnetic resistance canceling element comprises: A first cancellation bridge circuit configured to output a cosine wave signal; and The second canceling bridge circuit is configured to output a sine wave signal, The first detection bridge circuit includes a plurality of first detection magnetic resistance patterns. The second detection bridge circuit includes a plurality of second detection magnetoresistive patterns. The first compensation bridge circuit includes a plurality of first compensation magnetic resistance patterns, The second compensation bridge circuit includes a plurality of second compensation magnetic resistance patterns, The plurality of first detection magnetoresistance patterns, the plurality of first cancellation magnetoresistance patterns, the plurality of second detection magnetoresistance patterns, and the plurality of second cancellation magnetoresistance patterns are arranged along the circumference of the same circle in the order of first detection magnetoresistance patterns, first cancellation magnetoresistance patterns, second detection magnetoresistance patterns, and second cancellation magnetoresistance patterns.

2. The magnetic sensor according to claim 1, wherein: The first detection bridge circuit, the second detection bridge circuit, the first cancellation bridge circuit, and the second cancellation bridge circuit are arranged so that respective centers are identical to each other.

3. The magnetic sensor according to claim 1 or 2, wherein: Each of the detection magnetoresistive element and the cancellation magnetoresistive element is an anisotropic magnetoresistive element.

4. The magnetic sensor according to claim 1 or 2, wherein: The first detection bridge circuit includes four first detection magnetic resistance patterns, and the four first detection magnetic resistance patterns are full-bridge connected, and The second detection bridge circuit includes four second detection magnetoresistance patterns, and the four second detection magnetoresistance patterns are full-bridge connected.

5. The magnetic sensor according to claim 1 or 2, wherein: The first compensation bridge circuit includes four first compensation magnetic resistance patterns, and the four first compensation magnetic resistance patterns are full-bridge connected, and The second cancellation bridge circuit includes four second cancellation magnetic resistance patterns, and the four second cancellation magnetic resistance patterns are full-bridge connected.

6. The magnetic sensor according to claim 1 or 2, wherein: The first detection bridge circuit, the second detection bridge circuit, the first cancellation bridge circuit, and the second cancellation bridge circuit are arranged along the circumference of a circle.

7. The magnetic sensor according to claim 1 or 2, wherein: The detection magnetoresistive element and the cancellation magnetoresistive element are mounted on the same board.

8. A sensor system comprising: The magnetic sensor according to any one of claims 1 to 7; as well as The processing circuit is configured to perform signal processing on the output signal of the magnetic sensor.

9. The sensor system of claim 8, wherein: The processing circuit is configured to perform a differential operation on a first output signal of the detection magnetoresistive element and a second output signal of the cancellation magnetoresistive element and then amplify a result of the differential operation.

10. The sensor system of claim 8, wherein: The processing circuit is configured to amplify a first output signal of the detection magnetoresistive element and a second output signal of the cancellation magnetoresistive element, and then perform a differential operation on the amplified first output signal and the amplified second output signal.

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