Position detection circuit, position detection system, position detection method and program

Abstract

The purpose of the present disclosure is to improve the resolution of position sensing. A position-sensing circuit (2) comprises a processing circuit (21). A magnet member (3) includes a first track (4) having a plurality of first magnetic poles (40), and a second track (5) having a plurality of second magnetic poles (50). The magnetic pole pitch (P1) of the plurality of first magnetic poles (40) in a sensing direction (D1) differs from the magnetic pole pitch (P2) of the plurality of second magnetic poles (50) in the sensing direction (D1). A magnetic sensor (6) has a first sensor part (61) that senses magnetism generated in the first track (4), and a second sensor part (62) that senses magnetism generated in the second track (5). The processing circuit (21) obtains the position of the magnetic sensor (6) relative to the magnet member (3) on the basis of information pertaining to the phase of output from the first sensor part (61) and the phase of output from the second sensor part (62).

Description

[Technical Field]

[0001] The present disclosure generally relates to position sensing circuits, position sensing systems , position The present invention relates to a position detection method and a program, and more particularly to a position detection circuit and a position detection system that perform position detection using the output of a magnetic sensor. , position The present invention relates to a device detection method and a program. [Background technology]

[0002] The magnetic position detection device (position detection system) described in Patent Document 1 includes a magnetic scale, a magnetic sensing device, and a position calculation device. The magnetic scale is composed of a first magnetic scale and a second magnetic scale provided parallel to the first magnetic scale. The magnetic sensing device moves relatively in the movement direction within the magnetic field formed by the first magnetic scale and the second magnetic scale, and measures changes in the magnetic field during the relative movement using multiple magnetic sensing elements. The position calculation device calculates the absolute position between the magnetic scale and the magnetic sensing elements from the output values ​​of the magnetic sensing elements output from the magnetic sensing device.

[0003] In the magnetic position detection device described in Patent Document 1, the resolution of position detection is determined by the spacing between the multiple magnetic sensing elements. However, in the magnetic position detection device, it is difficult to improve the resolution of position detection due to restrictions on the spacing between the multiple magnetic sensing elements. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 063417 Summary of the Invention

[0005] The present disclosure relates to a position detection circuit and a position detection system that can improve the resolution of position detection. , position The present invention aims to provide a device detection method and program.

[0006] A position detection circuit according to one aspect of the present disclosure includes a processing circuit. The processing circuit processes the output of a magnetic sensor. The magnetic sensor detects a magnetism generated by a magnet member. The magnet member includes a first track having a plurality of first magnetic poles and a second track having a plurality of second magnetic poles. The plurality of first magnetic poles and the plurality of second magnetic poles are each a plurality of magnetic poles in which north poles and south poles are alternately arranged in a predetermined detection direction. The magnetic pole pitch of the plurality of first magnetic poles in the detection direction is different from the magnetic pole pitch of the plurality of second magnetic poles in the detection direction. The magnetic sensor includes: Two a first sensor unit; Two and a second sensor unit. Each of the two first sensor units detects a magnetic field generated in the first track, and each of the two second sensor units detects a magnetic field generated in the second track. At least one of the magnetic sensor and the magnet member moves along the detection direction relative to the other. The two first sensor units include one first sensor unit and the other first sensor unit, and the two second sensor units include one second sensor unit and the other second sensor unit. The processing circuitry Two First sensor section each The phase of the output of Two Second sensor section each The position of the magnetic sensor relative to the magnet member is determined based on information about the phase of the output of the magnetic sensor. The processing circuit determines that at least one of the first sensor units is abnormal when a difference between the output of the one first sensor unit when the one first sensor unit is in a first predetermined position and the output of the other first sensor unit when the other first sensor unit is in the first predetermined position is equal to or greater than a first predetermined value. The processing circuit determines that at least one of the second sensor units is abnormal when a difference between the output of the one second sensor unit when the one second sensor unit is in a second predetermined position and the output of the other second sensor unit when the other second sensor unit is in the second predetermined position is equal to or greater than a second predetermined value. .

[0007] A position detection system according to one aspect of the present disclosure includes the position detection circuit, the magnet member, and the magnetic sensor.

[0009] A position detection method according to one aspect of the present disclosure includes a processing step. In the processing step, an output of a magnetic sensor is processed. The magnetic sensor detects a magnetism generated by a magnet member. The magnet member includes a first track having a plurality of first magnetic poles and a second track having a plurality of second magnetic poles. The plurality of first magnetic poles and the plurality of second magnetic poles are each a plurality of magnetic poles in which north poles and south poles are alternately arranged in a predetermined detection direction. The magnetic pole pitch of the plurality of first magnetic poles in the detection direction is different from the magnetic pole pitch of the plurality of second magnetic poles in the detection direction. The magnetic sensor includes: Two a first sensor unit; Two and a second sensor unit. Each of the two first sensor units detects a magnetic field generated in the first track, and each of the two second sensor units detects a magnetic field generated in the second track.At least one of the magnetic sensor and the magnet member moves along the detection direction relative to the other. The two first sensor units include one first sensor unit and the other first sensor unit, and the two second sensor units include one second sensor unit and the other second sensor unit. In the processing step, Two First sensor section each The phase of the output of Two Second sensor section each The position of the magnetic sensor relative to the magnet member is determined based on information about the phase of the output of the magnetic sensor. In the processing step, it is determined that at least one of the first sensor units is abnormal if a difference between the output of the one first sensor unit when the one first sensor unit is in a first predetermined position and the output of the other first sensor unit when the other first sensor unit is in the first predetermined position is equal to or greater than a first predetermined value. In the processing step, it is determined that at least one of the second sensor units is abnormal if a difference between the output of the one second sensor unit when the one second sensor unit is in a second predetermined position and the output of the other second sensor unit when the other second sensor unit is in the second predetermined position is equal to or greater than a second predetermined value. .

[0010] A program according to one aspect of the present disclosure is a program for causing one or more processors to execute the position detection method. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a plan view of a position detection system according to a first embodiment. [Figure 2] 2A and 2B are circuit diagrams of a magnetic sensor of the position detection system. [Figure 3] 3A and 3B are graphs showing signals processed in the position detection system. [Figure 4] FIG. 4 is a side view of a main part of the magnetic sensor of the position detection system. [Figure 5] FIG. 5 is a flowchart showing an outline of a procedure for position detection by the position detection system. [Figure 6] FIG. 6 is a graph showing a signal processed by the position detection system. [Figure 7] FIG. 7 is a plan view of a position detection system according to a second modification of the first embodiment. [Figure 8] FIG. 8 is a plan view of a position detection system according to a third modification of the first embodiment. [Figure 9] FIG. 9 is a graph showing an example of a detection result of the position detection system. [Figure 10] FIG. 10 is a perspective view of a position detection system according to a fourth modification of the first embodiment. [Figure 11]FIG. 11 is a plan view of the position detection system according to the second embodiment. [Figure 12] FIG. 12 is a plan view of the position detection system, showing a state in which the magnet member has made a half turn from the state in FIG. [Figure 13] 13A to 13C are graphs showing signals processed by the position detection system. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a position detection circuit, a position detection system, and a magnet member according to embodiments will be described with reference to the drawings. However, each of the following embodiments is merely one of various embodiments of the present disclosure. Each of the following embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, each of the drawings described in each of the following embodiments is a schematic diagram, and the ratios of the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios.

[0013] (Embodiment 1) (1) Overview The position detection system 1 detects the position of a detection target using magnetism. The position detection system 1 is used, for example, as a position sensor such as a linear encoder or a rotary encoder. More specifically, the position detection system 1 is used, for example, as a position sensor (encoder) for detecting the position of a motor (linear motor or rotary motor) that drives a camera lens or the like. The position detection system 1 is also used, for example, as a position sensor for detecting the position of a brake pedal, brake lever, or shift lever of an automobile. Alternatively, the position detection system 1 is used as a reader for codes written with a magnetic material. However, the uses of the position detection system 1 are not limited to these. The "position" detected by the position detection system 1 is a concept that includes both the coordinates of the detection target and the rotation angle (orientation of the detection target) of the detection target around a rotation axis (virtual axis) that passes through the detection target. In other words, the position detection system 1 detects at least one of the coordinates of the detection target and the rotation angle of the detection target.

[0014] As shown in Fig. 1, the position detection system 1 of this embodiment includes a position detection circuit 2, a magnet member 3, and a magnetic sensor 6. The position detection circuit 2 includes a processing circuit 21. The processing circuit 21 processes the output of the magnetic sensor 6. The magnetic sensor 6 detects the magnetism generated by the magnet member 3.

[0015] The magnet member 3 includes a first track 4 and a second track 5. The first track 4 has a plurality of first magnetic poles 40. The second track 5 has a plurality of second magnetic poles 50. The plurality of first magnetic poles 40 and the plurality of second magnetic poles 50 are each a plurality of magnetic poles in which N poles and S poles are alternately arranged in a predetermined detection direction D1. The first track 4 and the second track 5 face each other in a direction D2 perpendicular to the detection direction D1. A magnetic pole pitch P1 of the plurality of first magnetic poles 40 in the detection direction D1 is different from a magnetic pole pitch P2 of the plurality of second magnetic poles 50 in the detection direction D1.

[0016] The magnetic sensor 6 has a first sensor unit 61 and a second sensor unit 62. The first sensor unit 61 detects the magnetism generated in the first track 4. The second sensor unit 62 detects the magnetism generated in the second track 5. At least one of the magnetic sensor 6 and the magnet member 3 moves along a detection direction D1 relative to the other.

[0017] The processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 based on information relating to the phase of the output of the first sensor unit 61 and the phase of the output of the second sensor unit 62.

[0018] According to the position detection system 1 and position detection circuit 2 of this embodiment, the resolution of position detection can be improved compared to when the processing circuit 21 performs position detection without using information regarding the phase of the output of the first sensor unit 61 and the phase of the output of the second sensor unit 62.

[0019] Furthermore, the magnetic sensor 6 only needs to have at least two sensor units, the first sensor unit 61 and the second sensor unit 62. This makes it possible to reduce the number of sensor units.

[0020] (2) Composition The position detection system 1, the position detection circuit 2, and the magnet member 3 will be described in more detail below.

[0021] As described above, at least one of the magnetic sensor 6 and the magnet member 3 moves along the detection direction D1 relative to the other. In this embodiment, as an example, a case will be described in which the magnetic sensor 6 moves along the detection direction D1 relative to the magnet member 3. That is, the magnetic sensor 6 of this embodiment is attached to a detection target whose position is to be detected, or is integrally incorporated into the detection target.

[0022] The position detection system 1 of this embodiment is used as an absolute encoder (linear encoder). That is, the position detection system 1 detects the absolute position of the magnetic sensor 6 with respect to the magnet member 3.

[0023] (2-1) Magnet components The shape of the magnet member 3 can be, for example, linear, arcuate, or annular. Typical examples of an arcuate shape are a circular arc and an elliptical arc. Typical examples of an annular shape are a circular ring and an ellipse. In this embodiment, a case where the shape of the magnet member 3 is linear will be described. The magnet member 3 has a length in the detection direction D1. That is, the shape of the magnet member 3 is linear along the detection direction D1.

[0024] In the magnet member 3, the first track 4 and the second track 5 are integrally formed. In FIG. 1, the first track 4 and the second track 5 are illustrated as being in contact with each other, but in reality, the first track 4 and the second track 5 are arranged with a predetermined distance between them. The first track 4 and the second track 5 may also be in contact with each other. The first track 4 and the second track 5 each have a length in the detection direction D1. The first track 4 and the second track 5 are each formed, for example, by printing magnetic ink on a sheet-like substrate.

[0025] The first track 4 and the second track 5 face each other in a direction D2 perpendicular to the detection direction D1. Furthermore, the longitudinal directions of the first track 4 and the second track 5 are both aligned with the detection direction D1. In other words, the second track 5 is arranged parallel to the first track 4.

[0026] The first track 4 has a plurality of first magnetic poles 40. The second track 5 has a plurality of second magnetic poles 50.

[0027] The multiple first magnetic poles 40 and the multiple second magnetic poles 50 are each a plurality of magnetic poles in which north poles and south poles are alternately arranged in the detection direction D1. In FIG. 1, north poles are marked with the letter "N" and south poles are marked with the letter "S." The lengths of the first magnetic poles 40 in the detection direction D1 are equal to each other. The lengths of the second magnetic poles 50 in the detection direction D1 are equal to each other. In the present disclosure, "equal" is not limited to the case where multiple values ​​are strictly equal, but also includes the case where multiple values ​​differ within an allowable error range.

[0028] The magnetic pole pitch P1 of the multiple first magnetic poles 40 in the detection direction D1 is, for example, a value within a range of 0.1 mm to 1 mm. Here, the magnetic pole pitch P1 of the multiple first magnetic poles 40 is defined as follows. That is, when tracing the multiple first magnetic poles 40 toward one side of the detection direction D1 (for example, toward the right if the detection direction D1 is the left-right direction), the magnetic pole pitch P1 is the distance from one end of one side of a certain first magnetic pole 40 to one end of the one side of the first magnetic pole 40 adjacent to this first magnetic pole 40. Note that the magnetic pole pitch P1 may be defined as the average value of the distances between the first magnetic poles 40. In this embodiment, since there are no gaps between the multiple first magnetic poles 40, the magnetic pole pitch P1 is equal to the length of each first magnetic pole 40 in the detection direction D1. There may be gaps between the multiple first magnetic poles 40.

[0029] The magnetic pole pitch P2 of the second magnetic poles 50 in the detection direction D1 is, for example, a value in the range of 0.1 mm to 1 mm. Here, the magnetic pole pitch P2 of the second magnetic poles 50 is defined as follows. That is, when tracing the second magnetic poles 50 toward one side of the detection direction D1 (for example, toward the right if the detection direction D1 is the left-right direction), the magnetic pole pitch P2 is the distance from one end of one side of a certain second magnetic pole 50 to one end of the one side of the second magnetic pole 50 adjacent to this second magnetic pole 50. Note that the magnetic pole pitch P2 may be defined as the average value of the distances between the second magnetic poles 50. In this embodiment, since there are no gaps between the second magnetic poles 50, the magnetic pole pitch P2 is equal to the length of each second magnetic pole 50 in the detection direction D1. There may be gaps between the second magnetic poles 50.

[0030] The magnet member 3 includes a detection region R1 facing the magnetic sensor 6. In this embodiment, the detection region R1 is a rectangular region. The magnetic sensor 6 moves relative to the magnet member 3 along the detection direction D1, at least within the region facing the detection region R1. In this embodiment, the movement range of the magnetic sensor 6 is limited so that at least a portion of the magnetic sensor 6 remains facing the detection region R1. In FIG. 1, the portion of the magnet member 3 outside the detection region R1 is shown by a two-dot chain line, but the portion of the magnet member 3 outside the detection region R1 is also a substantial portion of the magnet member 3.

[0031] Hereinafter, the number of magnetic poles among the multiple first magnetic poles 40 arranged within the detection region R1 will be referred to as the "first magnetic pole number." In this embodiment, the first magnetic pole number is four. Also, below, the number of magnetic poles among the multiple second magnetic poles 50 arranged within the detection region R1 will be referred to as the "second magnetic pole number." In this embodiment, the second magnetic pole number is three. That is, the magnet member 3 has the first magnetic poles 40 of the first magnetic pole number and the second magnetic poles 50 of the second magnetic pole number within the detection region R1. The first magnetic pole number and the second magnetic pole number are different from each other. The first magnetic pole number and the second magnetic pole number are relatively prime.

[0032] Furthermore, the first number of magnetic poles and the second number of magnetic poles are numbers close to each other. As an example, "the first number of magnetic poles and the second number of magnetic poles are numbers close to each other" means that the difference between the first number of magnetic poles and the second number of magnetic poles is smaller than the smaller of the first number of magnetic poles and the second number of magnetic poles. As another example, "the first number of magnetic poles and the second number of magnetic poles are numbers close to each other" means that the difference between the first number of magnetic poles and the second number of magnetic poles is 1 or less, 2 or less, or 3 or less. As another example, "the first number of magnetic poles and the second number of magnetic poles are numbers close to each other" means that the difference between the first number of magnetic poles and the second number of magnetic poles is 50% or less, 40% or less, or 30% or less of the larger of the first number of magnetic poles and the second number of magnetic poles.

[0033] The larger the dimensions of the second magnetic pole 50 relative to the dimensions of the first magnetic pole 40, the greater the influence of the second magnetic pole 50 on the magnetic field around the first magnetic pole 40. Furthermore, the larger the dimensions of the first magnetic pole 40 relative to the dimensions of the second magnetic pole 50, the greater the influence of the first magnetic pole 40 on the magnetic field around the second magnetic pole 50. In this embodiment, the number of first magnetic poles and the number of second magnetic poles are close to each other, so the difference between the dimensions of the first magnetic pole 40 and the second magnetic pole 50 is small. Therefore, the mutual influence between the first magnetic pole 40 and the second magnetic pole 50 can be reduced. This can improve the accuracy of position detection by the position detection system 1.

[0034] It is preferable that two or more first magnetic poles 40 and two or more second magnetic poles 50 are arranged within the detection region R1. In other words, it is preferable that the number of first magnetic poles and the number of second magnetic poles are each two or more. Note that if even a portion of the first magnetic pole 40 or the second magnetic pole 50 is arranged within the detection region R1, that magnetic pole is considered to be arranged within the detection region R1.

[0035] Both ends (first end 401 and second end 402) of the first magnetic pole 40 of the first magnetic pole number in the detection area R1 in the detection direction D1 overlap with both ends of the detection area R1 in the detection direction D1. Both ends (first end 501 and second end 502) of the second magnetic pole 50 of the second magnetic pole number in the detection area R1 in the detection direction D1 overlap with both ends of the detection area R1 in the detection direction D1.

[0036] In this way, the first magnetic poles 40 of the first number of magnetic poles and the second magnetic poles 50 of the second number of magnetic poles in the detection region R1 are arranged so that the positions of their respective first ends 401, 501 in the detection direction D1 are aligned. That is, the first ends 401, 501 of the first magnetic poles 40 of the first number of magnetic poles and the second magnetic poles 50 of the second number of magnetic poles are aligned in a direction D2 perpendicular to the detection direction D1. Furthermore, the first magnetic poles 40 of the first number of magnetic poles and the second magnetic poles 50 of the second number of magnetic poles are arranged so that the positions of their respective second ends 402, 502 in the detection direction D1 are aligned. That is, the second ends 402, 502 of the first magnetic poles 40 of the first number of magnetic poles and the second magnetic poles 50 of the second number of magnetic poles are aligned in a direction D2 perpendicular to the detection direction D1.

[0037] In the following, unless otherwise specified, the description will focus on only the first number (four) of first magnetic poles 40 in the detection region R1 out of the multiple first magnetic poles 40. In the following, unless otherwise specified, the description will focus on only the second number (three) of second magnetic poles 50 in the detection region R1 out of the multiple second magnetic poles 50.

[0038] Here, the four first magnetic poles 40 are distinguished from one another and are referred to as first magnetic poles 41, 42, 43, and 44, respectively. The four first magnetic poles 41, 42, 43, and 44 are arranged in this order in the detection direction D1. In the first track 4 of this embodiment, the first magnetic poles 41 and 43 are north poles, and the first magnetic poles 42 and 44 are south poles.

[0039] Here, the three second magnetic poles 50 are distinguished from one another and are referred to as second magnetic poles 51, 52, and 53, respectively. The three second magnetic poles 51, 52, and 53 are arranged in this order in the detection direction D1. In the second track 5 of this embodiment, the second magnetic poles 51 and 53 are N poles, and the second magnetic pole 52 is a S pole.

[0040] Within the detection region R1, the length of the first track 4 in the detection direction D1 is equal to the length of the second track 5 in the detection direction D1. That is, the relationship P1 × (number of first magnetic poles) = P2 × (number of second magnetic poles) holds among the magnetic pole pitch P1, the first number of magnetic poles (four), the magnetic pole pitch P2, and the second number of magnetic poles (three). The magnetic pole pitch P1 is shorter than the magnetic pole pitch P2.

[0041] (2-2) Magnetic sensor The magnetic sensor 6 includes a first sensor unit 61 and a second sensor unit 62. The first sensor unit 61 and the second sensor unit 62 are movable together in the detection direction D1. The first sensor unit 61 and the second sensor unit 62 are housed in, for example, the same package so that the first sensor unit 61 and the second sensor unit 62 can move together in the detection direction D1. Each of the first sensor unit 61 and the second sensor unit 62 of this embodiment includes an artificial lattice type GMR (Giant Magneto Resistive effect) element 63. More specifically, as shown in FIGS. 2A and 2B , each of the first sensor unit 61 and the second sensor unit 62 includes four GMR elements 63. The four GMR elements 63 are bridge-connected. That is, two series circuits, each consisting of two GMR elements 63, are connected between a power supply (Vcc) and ground (GND). The two series circuits are connected in parallel with each other. A first voltage is output between the two GMR elements 63 in one of the two series circuits. Hereinafter, the first voltage in the first sensor unit 61 will be referred to as a first voltage Vo1, and the first voltage in the second sensor unit 62 will be referred to as a first voltage Vo3. A second voltage is output between the two GMR elements 63 in the other of the two series circuits. Hereinafter, the second voltage in the first sensor unit 61 will be referred to as a second voltage Vo2, and the second voltage in the second sensor unit 62 will be referred to as a second voltage Vo4.

[0042] The four GMR elements 63 of the first sensor unit 61 are aligned in the sensing direction D1, and the spacing between each GMR element 63 is ¼ the magnetic pole pitch P1. The four GMR elements 63 of the second sensor unit 62 are aligned in the sensing direction D1, and the spacing between each GMR element 63 is ¼ the magnetic pole pitch P2. More specifically, the two GMR elements 63 (also referred to as 63A and 63C in FIGS. 2A and 2B) are arranged at a spacing of ½ the magnetic pole pitch P1 (or P2). The two GMR elements 63A and 63C are connected in series. A node N1 between the two GMR elements 63A and 63C is electrically connected to the output terminal of the first voltage Vo1 (or Vo3). Two GMR elements 63 (also referred to as 63B and 63D in FIGS. 2A and 2B) are arranged at an interval of ½ the magnetic pole pitch P1 (or P2). The two GMR elements 63B and 63D are connected in series. A node N2 between the two GMR elements 63B and 63D is electrically connected to the output terminal of the second voltage Vo2 (or Vo4). The GMR element 63B is arranged at a spatially intermediate position relative to the GMR elements 63A and 63C. The GMR element 63C is arranged at a spatially intermediate position relative to the GMR elements 63B and 63D. With this arrangement, in each of the first sensor unit 61 and the second sensor unit 62, the first voltage Vo1 and the second voltage Vo2 are out of phase with each other by P1 / 4 (see the middle part of FIG. 3A). Similarly, the first voltage Vo3 and the second voltage Vo4 are out of phase with each other by P2 / 4 (see the middle part of FIG. 3B). The horizontal axis of the Cartesian coordinate system in the middle of Figures 3A and 3B represents the coordinates of the first sensor unit 61 and the second sensor unit 62 in the detection direction D1, and the vertical axis represents the output (voltage) of the first sensor unit 61 and the second sensor unit 62.

[0043] As shown in FIG. 1, the first sensor unit 61 is disposed adjacent to the first track 4. Here, "adjacent" is a concept that encompasses a state in which multiple components located close to each other are in contact with each other and a state in which they are disposed apart from each other. The first sensor unit 61 detects the magnetism generated in the first track 4. The second sensor unit 62 is disposed adjacent to the second track 5. The second sensor unit 62 detects the magnetism generated in the second track 5.

[0044] As the first sensor unit 61 and the second sensor unit 62 move in the detection direction D1 relative to the magnet member 3, the positional relationship between the first sensor unit 61 and the second sensor unit 62 and the magnet member 3 changes, and the direction of the magnetic field at the positions of the first sensor unit 61 and the second sensor unit 62 changes. The electrical resistance of each GMR element 63 changes in response to the change in the direction of the magnetic field at the first sensor unit 61, and the first voltage Vo1 and the second voltage Vo2 change. Similarly, the electrical resistance of each GMR element 63 changes in response to the change in the direction of the magnetic field at the second sensor unit 62, and the first voltage Vo3 and the second voltage Vo4 change. In short, the first sensor unit 61 and the second sensor unit 62 output the first voltages Vo1 and Vo3 and the second voltages Vo2 and Vo4 corresponding to the positions of the first sensor unit 61 and the second sensor unit 62.

[0045] 3A and 3B, the coordinate axis (horizontal axis) representing the coordinates of the first sensor unit 61 and the second sensor unit 62 in the detection direction D1 and the coordinate axis (vertical axis) representing the output (voltage) of the first sensor unit 61 and the second sensor unit 62 are orthogonal to each other. In this orthogonal coordinate system, the output waveform of each of the first sensor unit 61 and the second sensor unit 62 is sinusoidal. That is, in this orthogonal coordinate system, the waveform of each of the first voltage Vo1 (or Vo3) and the second voltage Vo2 (or Vo4) is sinusoidal.

[0046] 3A illustrates a first magnetic pole 40 having a first number of magnetic poles corresponding to the coordinates of the first sensor unit 61 in the detection direction D1. Here, the coordinates of the first sensor unit 61 in the detection direction D1 refer to, for example, the coordinates of one end of the first sensor unit 61 in the detection direction D1 (the left end in FIG. 3A). Similarly, FIG. 3B illustrates a second magnetic pole 50 having a second number of magnetic poles corresponding to the coordinates of the second sensor unit 62 in the detection direction D1. Here, the coordinates of the second sensor unit 62 in the detection direction D1 refer to, for example, the coordinates of one end of the second sensor unit 62 in the detection direction D1 (the left end in FIG. 3B). The first sensor unit 61 and the second sensor unit 62 move in the detection direction D1 with their coordinates in the detection direction D1 coinciding with each other.

[0047] The magnitude of the outputs from the first sensor unit 61 and the second sensor unit 62 is equal when the magnetic field is oriented in a certain direction and when it is oriented in the opposite direction. While the first sensor unit 61 moves in the detection direction D1 a distance equal to the magnetic pole pitch P1, the direction (angle) of the magnetic field at the first sensor unit 61 changes by 180 degrees, so the first voltage Vo1 and the second voltage Vo2 change by one period. Similarly, while the second sensor unit 62 moves in the detection direction D1 a distance equal to the magnetic pole pitch P2, the direction (angle) of the magnetic field at the second sensor unit 62 changes by 180 degrees, so the first voltage Vo3 and the second voltage Vo4 change by one period.

[0048] (2-2-1) Structure of GMR element 4 shows a schematic structure of the GMR element 63. The GMR element 63 has a substrate 630 and a layered structure 640 formed on the substrate 630. The substrate 630 is, for example, a silicon substrate. This allows for low cost and miniaturization. The layered structure 640 contains, for example, cobalt and iron.

[0049] More specifically, the layered structure 640 is a metal layered structure. Each layer has a thickness of about several nanometers. Each layer contains several tens of atoms stacked in the thickness direction.

[0050] The laminated structure 640 is formed by alternately stacking magnetic layers 641 and non-magnetic layers 642. In other words, the laminated structure 640 has a spin valve structure. The number of layers in the laminated structure 640 is, for example, 10 or more or 20 or more. The magnetic layer 641 is a layer of a ferromagnetic material. The magnetic layer 641 is more easily magnetized than the non-magnetic layer 642. The magnetic layer 641 contains, for example, cobalt and iron. For example, the composition ratio of cobalt is equal to the composition ratio of iron. The non-magnetic layer 642 is a layer of a non-magnetic material. The non-magnetic layer 642 contains, for example, copper.

[0051] Conventionally, nickel has sometimes been used as the magnetic material constituting the magnetic layer 641 of the laminated structure 640. However, it is preferable that the laminated structure 640 does not contain nickel. This is because, when the laminated structure 640 is exposed to heat, nickel may diffuse into copper or other materials in the laminated structure 640, causing the laminated structure 640 to be unable to maintain its structure. Since the laminated structure 640 does not contain nickel, the heat resistance of the laminated structure 640 (magnetic sensor 6) can be improved. Furthermore, since the magnetic layer 641 contains cobalt and iron, the output of the GMR element 63 can be relatively large. It is preferable that the magnetic layer 641 contains only cobalt and iron.

[0052] Furthermore, since the non-magnetic layer 642 contains copper, it is possible to relatively increase the output of the GMR element 63 and to relatively reduce the hysteresis of the change in electrical resistance of the GMR element 63 in response to a change in magnetism. It is preferable that the non-magnetic layer 642 contains only copper.

[0053] (3) Processing circuit As shown in Fig. 1, the position detection circuit 2 of this embodiment includes only a processing circuit 21. The processing circuit 21 includes a computer system having one or more processors and a memory. At least some of the functions of the processing circuit 21 are realized by the processor of the computer system executing a program recorded in the memory of the computer system. The program may be recorded in the memory, or may be provided via a telecommunications line such as the Internet, or may be recorded on a non-transitory recording medium such as a memory card and provided.

[0054] The processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 based on the output of the first sensor unit 61 (first voltage Vo1 and second voltage Vo2) and the output of the second sensor unit 62 (first voltage Vo3 and second voltage Vo4). More specifically, the processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 based on information regarding the phase of the output of the first sensor unit 61 and the phase of the output of the second sensor unit 62. The position of the magnetic sensor 6 may be defined as any one point on the magnetic sensor 6. Here, as an example, the position of the magnetic sensor 6 is defined as the position of one end (the left end in FIG. 1 ) of the first sensor unit 61 in the detection direction D1.

[0055] An outline of the procedure for position detection by the position detection system 1 will be described with reference to FIG. 5. First, each of the first sensor unit 61 and the second sensor unit 62 of the magnetic sensor 6 detects magnetism (step ST1). Next, the processing circuit 21 determines a first determination value J1 based on the output of the first sensor unit 61, and determines a second determination value J2 based on the output of the second sensor unit 62 (step ST2). The first determination value J1 is a value corresponding to the phase of the output of the first sensor unit 61, and the second determination value J2 is a value corresponding to the phase of the output of the second sensor unit 62. Furthermore, the processing circuit 21 determines a third determination value J3 corresponding to the difference between the first determination value J1 and the second determination value J2 (step ST3). Then, the processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 based on the third determination value J3 (step ST4). This will be described in more detail below.

[0056] 3A and 3B, first voltages Vo1 and Vo3 and second voltages Vo2 and Vo4 having sinusoidal waveforms are input to the processing circuit 21. Next, the processing circuit 21 calculates a first determination value J1 using the following (Equation 1), and calculates a second determination value J2 using (Equation 2). (Number 1) J1=arctan(Vo1 / Vo2) (Vo1≧0, Vo2>0), J1=arctan(Vo1 / Vo2)+π (Vo2<0), J1=arctan(Vo1 / Vo2)+2π (Vo1<0, Vo2>0) (Number 2) J2=arctan(Vo3 / Vo4) (Vo3≧0, Vo4>0), J2=arctan(Vo3 / Vo4)+π (Vo4<0), J2=arctan(Vo3 / Vo4)+2π (Vo3<0, Vo4>0) When the first voltage Vo1 is a sine wave and the second voltage Vo2 is a sine wave whose phase is ahead of the first voltage Vo1 by P1 / 4 (here, P1 is normalized to P1=2π), the first judgment value J1 matches the phase of the first voltage Vo1 (the phase is greater than or equal to 0 and less than 2π). When the second voltage Vo2 is viewed as a cosine wave with the same phase as the first voltage Vo1, the first judgment value J1 also matches the phase of the second voltage Vo2 as a cosine wave (the phase is greater than or equal to 0 and less than 2π).

[0057] When the first voltage Vo3 is a sine wave and the second voltage Vo4 is a sine wave whose phase leads the first voltage Vo3 by P2 / 4 (here, P2 is normalized to P2=2π), the second judgment value J2 matches the phase of the first voltage Vo3 (the phase is greater than or equal to 0 and less than 2π). When the second voltage Vo4 is viewed as a cosine wave with the same phase as the first voltage Vo3, the second judgment value J2 also matches the phase of the second voltage Vo4 as a cosine wave (the phase is greater than or equal to 0 and less than 2π).

[0058] The first determination value J1 and the second determination value J2 are illustrated in the lower parts of FIGS. 3A and 3B and the middle part of FIG. 6. In the Cartesian coordinate systems shown in the lower parts of FIGS. 3A and 3B and the middle part of FIG. 6, the coordinate axis (horizontal axis) representing the coordinates of the first sensor unit 61 and the second sensor unit 62 in the detection direction D1 and the coordinate axis (vertical axis) representing the first determination value J1 and the second determination value J2 are mutually orthogonal. In the Cartesian coordinate systems shown in the lower parts of FIGS. 3A and 3B and the middle part of FIG. 6, the first determination value J1 and the second determination value J2 are sawtooth-wave shaped. More specifically, as the coordinate in the detection direction D1 changes across the ends of each magnetic pole (the first magnetic pole 40 and the second magnetic pole 50), the first determination value J1 and the second determination value J2 change linearly. The same waveform is repeated for each interval between the ends of each magnetic pole (magnetic pole pitches P1 and P2). That is, the first determination value J1 monotonically increases (or decreases) within the magnetic pole pitch P1. As a result, the values ​​of any two points of the first determination value J1 are different within the magnetic pole pitch P1. Furthermore, the second determination value J2 monotonically increases (or decreases) within the magnetic pole pitch P2. As a result, the values ​​of any two points of the second determination value J2 are different within the magnetic pole pitch P2.

[0059] Furthermore, the processing circuit 21 determines a value corresponding to the difference between the first determination value J1 and the second determination value J2 as a third determination value J3. That is, the processing circuit 21 determines the position of the magnetic sensor 6 with respect to the magnet member 3 based on the third determination value J3, which is a value corresponding to the difference between the first determination value J1 based on the output of the first sensor unit 61 and the second determination value J2 based on the output of the second sensor unit 62. The third determination value J3 can be determined, for example, by the following (Equation 3). (Number 3) J3=J1-J2+2π The difference between (J1+2π) and the second judgment value J2 in the middle of Fig. 6 is equal to the third judgment value J3 in the bottom of Fig. 6. Note that, for ease of explanation, the third judgment value J3 is calculated using Equation 3 above, but in practice, the third judgment value J3 may be calculated using the following Equation 4. (Number 4) J3=J1-J2 The third determination value J3 may be calculated using either (Equation 3) or (Equation 4). Depending on whether the third determination value J3 is calculated using (Equation 3) or (Equation 4), an arithmetic expression or a data table or the like that indicates the relationship between the third determination value J3 and the position of the magnetic sensor 6 may be set appropriately.

[0060] In the Cartesian coordinate system shown in the lower part of FIG. 6, the coordinate axis (horizontal axis) representing the coordinates of the first sensor unit 61 and the second sensor unit 62 in the detection direction D1 and the coordinate axis (vertical axis) representing the third determination value J3 are orthogonal to each other. In FIG. 6, the dotted lines are auxiliary lines and do not represent the values ​​of the first to third determination values ​​J1 to J3. As shown in the lower part of FIG. 6, when the movement range of the magnetic sensor 6 is limited to the area facing the detection area R1, the third determination value J3 varies depending on the position throughout almost the entire movement range of the magnetic sensor 6. However, the value when the magnetic sensor 6 faces one end of the detection area R1 (the value at the left end of FIG. 6) is the same as the value when the magnetic sensor 6 faces the other end of the detection area R1 (the value at the right end of FIG. 6).

[0061] Therefore, the processing circuit 21 can uniquely determine the position of the magnetic sensor 6 based on the third determination value J3 throughout substantially the entire movement range of the magnetic sensor 6. The position detection system 1 may be configured to restrict movement of the magnetic sensor 6 to a position facing one end or the other end of the detection region R1. By limiting the movement range of the magnetic sensor 6 in this manner, the processing circuit 21 can uniquely determine the position of the magnetic sensor 6 based on the third determination value J3 throughout the entire movement range of the magnetic sensor 6. In other words, the processing circuit 21 can determine a different position as the position of the magnetic sensor 6 for each magnitude of the third determination value J3.

[0062] The processing circuit 21 may store in memory, for example, the relationship between the third determination value J3 and the position of the magnetic sensor 6 in the form of an arithmetic expression or a data table. The processing circuit 21 can determine the position of the magnetic sensor 6 from the third determination value J3 by referring to the arithmetic expression or the data table. That is, the third determination value J3 represented on the vertical axis in the lower part of FIG. 6 may be converted into coordinates (the position of the magnetic sensor 6) represented on the horizontal axis.

[0063] In this way, the processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 based on information about the phase of the output of the first sensor unit 61 (the first voltage Vo1 and the second voltage Vo2) and the phase of the output of the second sensor unit 62 (the first voltage Vo3 and the second voltage Vo4). That is, in the process of converting the first voltage Vo1 and the second voltage Vo2 into the first determination value J1, information about the phase of the first voltage Vo1 and the second voltage Vo2 is held in the first determination value J1. In other words, the first determination value J1 includes information about the phase of the first voltage Vo1 and the second voltage Vo2. Furthermore, in the process of converting the first voltage Vo3 and the second voltage Vo4 into the second determination value J2, information about the phase of the first voltage Vo3 and the second voltage Vo4 is held in the second determination value J2. In other words, the second determination value J2 includes information about the phase of the first voltage Vo3 and the second voltage Vo4. Furthermore, in the process of converting the first determination value J1 and the second determination value J2 into the third determination value J3, information regarding the phases of the first voltages Vo1, Vo3 and the second voltages Vo2, Vo4 is retained in the third determination value J3. In other words, the third determination value J3 includes information regarding the phases of the first voltages Vo1, Vo3 and the second voltages Vo2, Vo4. Then, the processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 based on the third determination value J3.

[0064] It is not necessary for all of the information regarding the phases of the first voltages Vo1 and Vo3 and the second voltages Vo2 and Vo4 to be retained in the first determination value J1, the second determination value J2, or the third determination value J3, but it is sufficient for at least a portion of the information to be retained. For example, the first voltage Vo1 and the second voltage Vo2 may be converted into the first determination value J1 having a period half the period of these voltages, so that only half of the phase information is retained in the first determination value J1.

[0065] As described above, the first determination value J1 and the second determination value J2 change linearly as the coordinates of the first sensor unit 61 and the second sensor unit 62 in the detection direction D1 change between the ends of each magnetic pole (the first magnetic pole 40 and the second magnetic pole 50). That is, the outputs of the first sensor unit 61 and the second sensor unit 62 differ for each position between the ends of the magnetic pole. Furthermore, the first magnetic poles 40 with the first number of magnetic poles and the second magnetic poles 50 with the second number of magnetic poles are arranged within the detection region R1, and the first and second magnetic pole numbers are relatively prime. As a result, throughout substantially the entire detection region R1, the combinations of the first determination value J1 and the second determination value J2 calculated from the outputs of the first sensor unit 61 and the second sensor unit 62 differ from the combinations of the first determination value J1 and the second determination value J2 calculated at other positions. Therefore, the processing circuit 21 can uniquely determine the position of the magnetic sensor 6 in substantially the entire detection region R1 based on the first determination value J1 and the second determination value J2.

[0066] Furthermore, in this manner, the processing circuit 21 converts the outputs of the first sensor unit 61 and the second sensor unit 62 into coordinates (position) of the magnetic sensor 6. In the conversion process, for example, no processing such as binarizing the outputs of the first sensor unit 61 and the second sensor unit 62 is performed. Therefore, even a slight change in the outputs of the first sensor unit 61 and the second sensor unit 62 also changes the coordinates (position) of the magnetic sensor 6 determined by the processing circuit 21. More specifically, the resolution of position detection regarding the position of the magnetic sensor 6 corresponds to the resolution of the outputs of the first sensor unit 61 and the second sensor unit 62. Therefore, it is possible to prevent the resolution of position detection from becoming smaller than the resolution of the outputs of the first sensor unit 61 and the second sensor unit 62.

[0067] Since the output of the first sensor unit 61 and the output of the second sensor unit 62 are sinusoidal, it is easy to match the output of the first sensor unit 61 and the output of the second sensor unit 62 with the position of the magnetic sensor 6. This improves the accuracy of position detection. It is preferable that the output of the first sensor unit 61 and the output of the second sensor unit 62 are close to an accurate sine wave.

[0068] Preferably, the position detection system 1 further includes an output unit 7 (see FIG. 1). The output unit 7 outputs position information indicating the position of the magnetic sensor 6 determined by the processing circuit 21. The output unit 7 may, for example, output the position information to a memory provided inside or outside the position detection system 1, and store the position information. Alternatively, the output unit 7 may output the position information to a presentation unit such as a display or speaker provided inside or outside the position detection system 1, and the presentation unit may present the position information by image or sound.

[0069] (Modification 1 of Embodiment 1) A position detection system 1 according to a first modification of the first embodiment will be described below with reference to Fig. 1. The position detection system 1 of the first modification differs from that of the first embodiment in the processing performed by the processing circuit 21. The same components as those of the first embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

[0070] The first sensor unit 61 corresponds to the first track 4, and the second sensor unit 62 corresponds to the second track 5. The processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 with a resolution corresponding to the resolution of the output of the sensor unit corresponding to the track with the smaller magnetic pole pitch between the first track 4 and the second track 5. In this first modification, the magnetic pole pitch P1 of the first magnetic poles 40 with the first magnetic pole number in the first track 4 is smaller than the magnetic pole pitch P2 of the second magnetic poles 50 with the second magnetic pole number in the second track 5. Therefore, the processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 with a resolution corresponding to the resolution of the output (first voltage Vo1 and second voltage Vo2) of the first sensor unit 61 corresponding to the first track 4.

[0071] The processing circuit 21 performs a first process to determine one or more candidate positions of the magnetic sensor 6 by, for example, referring to a first data table indicating the relationship between the first determination value J1 and the position of the magnetic sensor 6. Furthermore, the processing circuit 21 performs a second process to determine a position corresponding to the second determination value J2 from among the one or more candidate positions of the magnetic sensor 6 by referring to a second data table indicating the relationship between the second determination value J2 and the position of the magnetic sensor 6. The processing circuit 21 uses the position determined by the second process as the final output representing the position of the magnetic sensor 6. That is, in the first process, the position of the magnetic sensor 6 on the first magnetic pole 40 is determined by the first data table, and in the second process, the magnetic pole where the magnetic sensor 6 is located is determined from the first magnetic poles 40 of the first magnetic pole number by the second data table. The position resolution of the magnetic sensor 6 relative to the magnet member 3 is determined by the first process, which is performed based on the output of the first sensor unit 61. That is, the position resolution of the magnetic sensor 6 relative to the magnet member 3 corresponds to the resolution of the output of the first sensor unit 61.

[0072] As a specific example, in FIG. 3, four coordinates exist for each value of the first determination value J1, and the four coordinates are set as candidates for the position of the magnetic sensor 6 by the first process. Furthermore, of the four coordinates, one coordinate corresponding to the second determination value J2 is found by the second process and set as the final output representing the position of the magnetic sensor 6. More specifically, for example, when J1=0 and J2=π, the coordinates corresponding to the first determination value J1 are the coordinates of the left ends of the first magnetic poles 41, 42, 43, and 44, so there are four candidates, and of the four candidates, only the coordinate of the left end of the first magnetic pole 43 corresponds to the second determination value J2. Therefore, the processing circuit 21 sets the coordinate of the left end of the first magnetic pole 43 as the final output representing the position of the magnetic sensor 6.

[0073] The magnetic pole pitch P1 is smaller than the magnetic pole pitch P2. Therefore, as shown in FIGS. 3A and 3B, the period of the first voltage Vo1 and the second voltage Vo2 of the first sensor unit 61 relative to the change in position of the magnetic sensor 6 is shorter than the period of the first voltage Vo3 and the second voltage Vo4 of the second sensor unit 62. Furthermore, when the position of the magnetic sensor 6 changes by a certain distance, the amount of change in the first voltage Vo1 and the second voltage Vo2 of the first sensor unit 61 is larger than the amount of change in the first voltage Vo3 and the second voltage Vo4 of the second sensor unit 62. Since the processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 with a resolution corresponding to the resolution of the output of the first sensor unit 61, the position resolution of the magnetic sensor 6 is relatively high. In other words, the position resolution of the magnetic sensor 6 is higher than when the processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 with a resolution corresponding to the resolution of the output (first voltage Vo3 and second voltage Vo4) of the second sensor unit 62.

[0074] In the first modification, the position of the magnetic sensor 6 is determined using a data table. However, the position of the magnetic sensor 6 may be determined using an arithmetic expression instead of a data table.

[0075] (Modification 2 of Embodiment 1) A position detection system 1 according to Modification 2 of Embodiment 1 will be described below with reference to Fig. 7. The same components as those in Embodiment 1 will be denoted by the same reference numerals and description thereof will be omitted.

[0076] The position detection system 1 of the present modified example 2 differs from that of the first embodiment in the configuration of the magnetic sensor 6. That is, the magnetic sensor 6 has a plurality of first sensor units 61 and a plurality of second sensor units 62. The plurality of first sensor units 61 (two in FIG. 7) are aligned in the detection direction D1. The plurality of second sensor units 62 (two in FIG. 7) are aligned in the detection direction D1.

[0077] The two first sensor units 61 are disposed adjacent to the first track 4. Each of the two first sensor units 61 detects the magnetic field generated in the first track 4. The two second sensor units 62 are disposed adjacent to the second track 5. Each of the two second sensor units 62 detects the magnetic field generated in the second track 5.

[0078] The processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 based on the outputs of the two first sensor units 61 and the two second sensor units 62. The position of the magnetic sensor 6 may be defined as any one point of the magnetic sensor 6. Here, as an example, the position of the magnetic sensor 6 is defined as the position of one end (the left end in FIG. 7) of one of the two first sensor units 61 (the left first sensor unit 61 in FIG. 7) in the detection direction D1.

[0079] The processing circuit 21 determines the third determination value J3 in the same manner as in the first embodiment, for example, based on the output of one first sensor unit 61 (the first sensor unit 61 on the right in FIG. 7 ) and the output of one second sensor unit 62 (the second sensor unit 62 on the right in FIG. 7 ). Furthermore, the processing circuit 21 similarly determines the third determination value J3 based on the output of the other first sensor unit 61 (the first sensor unit 61 on the left in FIG. 7 ) and the output of the other second sensor unit 62 (the second sensor unit 62 on the left in FIG. 7 ). That is, the processing circuit 21 determines two third determination values ​​J3. Furthermore, the processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 based on the two third determination values ​​J3. More specifically, the processing circuit 21 determines the position of the magnetic sensor 6 relative to the magnet member 3 by referring to an arithmetic expression or a data table based on the combination of the two third determination values ​​J3, for example.

[0080] According to the present modified example 2, the accuracy of position detection can be improved compared to when the magnetic sensor 6 has only one first sensor unit 61 and one second sensor unit 62.

[0081] The processing circuit 21 may also compare the outputs of the two first sensor units 61. This allows the processing circuit 21 to determine whether or not the two first sensor units 61 are abnormal. For example, the processing circuit 21 calculates a difference between the output of one first sensor unit 61 when the first sensor unit 61 is in a predetermined position and the output of the other first sensor unit 61 when the other first sensor unit 61 is in the same predetermined position. If the difference is equal to or greater than a predetermined value, the processing circuit 21 determines that at least one of the first sensor units 61 is abnormal. The two first sensor units 61 may also be arranged so that the distance between them is an integer multiple of the magnetic pole pitch P1. If the difference between the outputs of the two first sensor units 61 is equal to or greater than a predetermined value, the processing circuit 21 may determine that at least one of the first sensor units 61 is abnormal.

[0082] Similarly, the processing circuit 21 may compare the outputs of the two second sensor units 62. In this way, the processing circuit 21 may determine whether or not the two second sensor units 62 are abnormal. Alternatively, the two second sensor units 62 may be arranged so that the distance between them is an integer multiple of the magnetic pole pitch P2. Then, the processing circuit 21 may determine that at least one of the second sensor units 62 is abnormal when the difference between the outputs of the two second sensor units 62 is equal to or greater than a predetermined value.

[0083] (Modification 3 of Embodiment 1) A position detection system 1 according to a third modification of the first embodiment will be described below with reference to Fig. 8. The same components as those in the first embodiment are denoted by the same reference numerals and will not be described again. Note that the processing circuit 21 and the output unit 7 are not shown in Fig. 8.

[0084] In the position detection system 1 of the present modified example 3, the shape of the magnet member 3A is different from the shape of the magnet member 3 of the first embodiment. That is, the shape of the magnet member 3A is arc-shaped. More specifically, the shape of the magnet member 3A is arc-shaped. The position detection system 1 of the present modified example 3 is used as an encoder that detects the movement of the magnetic sensor 6 along the shape of the magnet member 3A.

[0085] The first track 4A and the second track 5A of the magnet member 3A are each shaped like an arc. More specifically, the first track 4A and the second track 5A are each shaped like a circular arc. The first track 4A and the second track 5A are concentrically arranged so as to be adjacent to each other in the radial direction. The first track 4A is arranged on the opposite side of the center C1 of the arc, and the second track 5A is arranged on the center C1 side of the arc. The multiple first magnetic poles 40 are aligned in a detection direction D1 that is aligned with the direction of the arc of the magnet member 3A. The multiple second magnetic poles 50 are aligned in the detection direction D1.

[0086] The magnetic pole pitch P1 of the multiple first magnetic poles 40 and the magnetic pole pitch P2 of the multiple second magnetic poles 50 are defined as lengths on the same arc A1 centered on the center C1. That is, the first track 4A and the second track 5A are projected onto the arc A1 in the radial direction (direction D2) of the magnet member 3A. When the multiple first magnetic poles 40 are traced on the arc A1 toward one side of the detection direction D1, the magnetic pole pitch P1 is the distance from one end of a certain first magnetic pole 40 on the one side to one end of the first magnetic pole 40 adjacent to this first magnetic pole 40. The magnetic pole pitch P1 is equal to the length of each first magnetic pole 40 projected onto the arc A1 in the detection direction D1. Furthermore, when tracing multiple second magnetic poles 50 on the arc A1 toward one side of the detection direction D1, the distance from one end of a certain second magnetic pole 50 on the one side to one end of the second magnetic pole 50 adjacent to this second magnetic pole 50 is the magnetic pole pitch P2. The magnetic pole pitch P2 is equal to the length of each second magnetic pole 50 projected onto the arc A1 in the detection direction D1.

[0087] The detection region R1 is an arc-shaped region. The magnet member 3A has a first number of first magnetic poles 40 and a second number of second magnetic poles 50 within the detection region R1.

[0088] The magnetic sensor 6 rotates around the center C1 of the arc of the magnet member 3A, so that the movement direction of the magnetic sensor 6 coincides with the detection direction D1.

[0089] According to the present modification 3, the movement of the magnetic sensor 6 relative to the magnet member 3A is movement along the arc shape of the magnet member 3A. That is, the position detection system 1 can detect the movement of the magnetic sensor 6 along the arc shape.

[0090] FIG. 9 shows an example of the detection result of the position of the magnetic sensor 6 relative to the magnet member 3A, obtained by the position detection system 1 of Modification 3. The horizontal axis of FIG. 9 represents the actual rotation angle of the magnetic sensor 6 around the center C1. The vertical axis of FIG. 9 represents the magnitude of the error in the detection result of the position detection system 1 relative to the value on the horizontal axis. The magnitude of the error in the detection result of the position detection system 1 is within ±0.1°.

[0091] The magnetic sensor 6 may be movable along the detection direction D1 (circumferential direction) to a position facing an area of ​​the magnet member 3A outside the detection area R1. In this case, the processing circuit 21 can detect the relative position of the magnetic sensor 6 based on the output of the first sensor unit 61 and the output of the second sensor unit 62. That is, in this case, the position detection system 1 is used as an incremental encoder that detects the relative position.

[0092] The magnet member 3A may have an annular shape or a circular ring shape.

[0093] (Fourth Modification of First Embodiment) A position detection system 1 according to a fourth modification of the first embodiment will be described below with reference to Fig. 10. The same components as those in the first embodiment are denoted by the same reference numerals and will not be described again. Note that the processing circuit 21 and the output unit 7 are not shown in Fig. 10.

[0094] In the position detection system 1 of the present modification 4, the shape of the magnet member 3B is different from the shape of the magnet member 3 of the first embodiment. That is, the shape of the magnet member 3B is annular. More specifically, the shape of the magnet member 3B is annular. The position detection system 1 of the present modification 4 is used as a rotary encoder.

[0095] The position detection system 1 further includes a holding member 8 that holds the magnet member 3B. The holding member 8 has a first rotor 81, a second rotor 82, and a shaft 83. The first rotor 81 and the second rotor 82 are disk-shaped. The shaft 83 connects the first rotor 81 and the second rotor 82. The first rotor 81, the second rotor 82, and the shaft 83 rotate integrally with the shaft 83 as an axis.

[0096] The first magnetic poles 40 are aligned in a detection direction D1, which is the same direction as the rotation direction of the holding member 8. The first magnetic poles 40 are attached to the outer peripheral surface of the first rotor 81.

[0097] The second magnetic poles 50 are arranged in the detection direction D1. The second magnetic poles 50 are attached to the outer circumferential surface of the second rotor .

[0098] The magnet member 3B has a first number of first magnetic poles 40 and a second number of second magnetic poles 50 within the detection region R1.

[0099] The magnetic sensor 6 is held by a member provided separately from the holding member 8. In this modification, of the magnetic sensor 6 and the magnet member 3B, the magnet member 3B moves (rotates). The processing circuit 21 determines the rotation angle of the magnet member 3B based on the output of the magnetic sensor 6.

[0100] As shown in the fourth modification, the position detection system 1 can be used as a rotary encoder.

[0101] (Other Modifications of the First Embodiment) Other variations of the first embodiment are listed below. The following variations may be implemented in appropriate combinations. The following variations may also be implemented in appropriate combinations with the above-described variations.

[0102] The position detection system 1 uses a magnet member 3. The magnet member 3 can be distributed on the market as a single magnet member 3, independent of other components of the position detection system 1.

[0103] Functions similar to those of the position detection circuit 2 and the position detection system 1 may be embodied as a position detection method, a (computer) program, or a non-transitory recording medium on which the program is recorded.

[0104] A position detection method according to one embodiment includes processing steps. In the processing steps, an output of a magnetic sensor 6 is processed. The magnetic sensor 6 detects a magnetic field generated by a magnet member 3. The magnet member 3 includes a first track 4 having a plurality of first magnetic poles 40 and a second track 5 having a plurality of second magnetic poles 50. The plurality of first magnetic poles 40 and the plurality of second magnetic poles 50 are each a plurality of magnetic poles in which north poles and south poles are alternately arranged in a predetermined detection direction D1. A magnetic pole pitch P1 of the plurality of first magnetic poles 40 in the detection direction D1 is different from a magnetic pole pitch P2 of the plurality of second magnetic poles 50 in the detection direction D1. The magnetic sensor 6 includes a first sensor unit 61 that detects a magnetic field generated by the first track 4 and a second sensor unit 62 that detects a magnetic field generated by the second track 5. At least one of the magnetic sensor 6 and the magnet member 3 moves along the detection direction D1 relative to the other. In the processing step, the position of the magnetic sensor 6 relative to the magnet member 3 is determined based on information relating to the phase of the output of the first sensor unit 61 and the phase of the output of the second sensor unit 62.

[0105] A program according to one aspect is a program for causing one or more processors to execute the position detection method described above.

[0106] The position detection system 1 of the present disclosure includes a computer system. The computer system is primarily composed of a processor and memory as hardware. The processor executes a program stored in the memory of the computer system to realize the functions of the position detection system 1 of the present disclosure. The program may be pre-stored in the memory of the computer system, provided via a telecommunications line, or provided in a non-transitory recording medium readable by the computer system, such as a memory card, optical disk, or hard disk drive. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The integrated circuits, such as ICs and LSIs, are referred to by different names depending on the degree of integration, and include integrated circuits called system LSIs, very large-scale integrations (VLSIs), and ultra-large-scale integrations (ULSIs). Furthermore, field-programmable gate arrays (FPGAs), which are programmed after the LSI is manufactured, or logic devices that allow the reconfiguration of internal connections or internal circuit partitions of the LSI, can also be used as processors. The electronic circuits may be integrated into one chip or distributed across multiple chips. The chips may be integrated into one device or distributed across multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0107] Furthermore, it is not essential for the position detection system 1 that multiple functions are concentrated in one housing, and the components of the position detection system 1 may be distributed across multiple housings. Furthermore, at least some of the functions of the position detection system 1 may be realized by the cloud (cloud computing) or the like.

[0108] Conversely, in the first embodiment, at least some of the functions of the position detection system 1 that are distributed among multiple devices may be integrated into one housing.

[0109] The magnetic sensor 6 may be movable along the detection direction D1 to a position facing a region of the magnet member 3 outside the detection region R1. In this case, the processing circuit 21 can detect the relative position of the magnetic sensor 6 based on the output of the first sensor unit 61 and the output of the second sensor unit 62. That is, in this case, the position detection system 1 is used as an incremental encoder that detects the relative position.

[0110] Furthermore, when the magnetic sensor 6 is located opposite a region of the magnet member 3 that is outside the detection region R1, the processing circuit 21 may detect the relative position of the magnetic sensor 6 based on the output of at least one of the first sensor unit 61 and the second sensor unit 62. On the other hand, when the magnetic sensor 6 is located opposite a region of the magnet member 3 that is outside the detection region R1, the processing circuit 21 may detect the absolute position of the magnetic sensor 6 based on the outputs of both the first sensor unit 61 and the second sensor unit 62.

[0111] It is not essential to calculate the first determination value J1, the second determination value J2, and the third determination value J3. The processing circuit 21 may calculate the position of the magnetic sensor 6 directly from the first voltages Vo1, Vo3 and the second voltages Vo2, Vo4. Alternatively, the processing circuit 21 may calculate the position of the magnetic sensor 6 directly from the first determination value J1 and the second determination value J2. In other words, just as the third determination value J3 differs for each position throughout substantially the entire range of movement of the magnetic sensor 6, the combinations of the first voltages Vo1, Vo3 and the second voltages Vo2, Vo4, and the combinations of the first determination value J1 and the second determination value J2 also differ for each position. Therefore, the processing circuit 21 can uniquely calculate the position of the magnetic sensor 6 throughout substantially the entire range of movement of the magnetic sensor 6 from the combinations of the first voltages Vo1, Vo3 and the second voltages Vo2, Vo4 or the combinations of the first determination value J1 and the second determination value J2.

[0112] Alternatively, the processing circuit 21 may determine the position of the magnetic sensor 6 based on at least one of the first determination value J1 and the second determination value J2 and the third determination value J3.

[0113] The magnetic pole pitch P1 may be defined as the length of each of the multiple first magnetic poles 40 in the sensing direction D1. Alternatively, the magnetic pole pitch P1 may be defined as the average value of the lengths of each of the multiple first magnetic poles 40 in the sensing direction D1.

[0114] The magnetic pole pitch P2 may be defined as the length of each of the plurality of second magnetic poles 50 in the sensing direction D1. Alternatively, the magnetic pole pitch P2 may be defined as the average value of the lengths of each of the plurality of second magnetic poles 50 in the sensing direction D1.

[0115] It is not essential that the number of first magnetic poles and the number of second magnetic poles are close to each other.

[0116] The magnetic sensor 6 is not limited to a sensor including an artificial lattice type GMR element 63. The magnetic sensor 6 may be, for example, a sensor including an SMR (Semiconductor Magneto Resistive) element or an AMR (Anisotropic Magneto Resistive) element.

[0117] The substrate 630 of the GMR element 63 is not limited to a silicon substrate, but may be, for example, a glass-glazed substrate obtained by glazing an alumina substrate with glass.

[0118] (Embodiment 2) (1) Overview A position detection system 1C according to the second embodiment will be described below with reference to Figs. 11 to 13C. The same components as those in the first embodiment are denoted by the same reference numerals and will not be described again. Note that the processing circuit 21 and the output unit 7 are not shown in Figs. 11 and 12.

[0119] The position detection system 1C of this embodiment is used as a rotary encoder that detects the rotational movement of the magnet member 3C or the magnetic sensor 6C. More specifically, the position detection system 1C is used as an absolute rotary encoder. That is, the position detection system 1C detects the absolute rotation angle of the magnetic sensor 6C relative to the magnet member 3C.

[0120] At least one of the magnetic sensor 6C and the magnet member 3C rotates relative to the other. More specifically, at least one of the magnetic sensor 6C and the magnet member 3C rotates 360 degrees relative to the other. In this embodiment, of the magnet member 3C and the magnetic sensor 6C, the magnet member 3C rotates. FIG. 12 shows a state in which the magnet member 3C has rotated 180 degrees from the state in FIG. 11. The rotational movement is movement along the detection direction D1, which is a direction around the virtual axis VA1. More specifically, the rotational movement is movement with the virtual axis VA1 as the rotation axis.

[0121] Since the magnet member 3C rotates 360 degrees relative to the magnetic sensor 6C, the range (detection area) of the magnet member 3C that faces the magnetic sensor 6C is a range that goes around the magnet member 3C.

[0122] (2) Magnet components The first track 4C and the second track 5C of the magnet member 3C are each formed by printing magnetic ink on a sheet-like substrate 30. The thickness direction of the substrate 30 is along the length direction of the imaginary axis VA1 (the depth direction of the paper in FIG. 11). When viewed from the length direction of the imaginary axis VA1, the substrate 30, the first track 4C, and the second track 5C each have an annular shape. More specifically, the substrate 30, the first track 4C, and the second track 5C each have an annular shape.

[0123] The substrate 30, the first track 4C, and the second track 5C surround a common imaginary axis VA1. The centers C1 of the substrate 30, the first track 4C, and the second track 5C coincide with each other. The imaginary axis VA1 passes through the center C1.

[0124] The plurality of first magnetic poles 40 and the plurality of second magnetic poles 50 are each a plurality of magnetic poles in which north poles and south poles are alternately arranged in the detection direction D1 (rotation direction). In Fig. 11, some of the north poles are marked with the letter "N" and some of the south poles are marked with the letter "S." The north poles and south poles are distinguished by the shade of the shading.

[0125] The lengths of the first magnetic poles 40 in the detection direction D1 are equal to each other. The lengths of the second magnetic poles 50 in the detection direction D1 are equal to each other. In the detection direction D1, the length of each of the multiple first magnetic poles 40 (magnetic pole pitch P1) is longer than the length of each of the multiple second magnetic poles 50 (magnetic pole pitch P2). The method of defining the magnetic pole pitches P1 and P2 is the same as in Modification 3 of Embodiment 1, and therefore description thereof will be omitted.

[0126] The number of the first magnetic poles 40 and the number of the second magnetic poles 50 are even numbers. A line SL1 in FIG. 11 is a line that divides the magnet member 3C into two equal parts. The difference between the number of the first magnetic poles 40 and the number of the second magnetic poles 50 is 2. Therefore, the magnet member 3C has a two-fold symmetric shape. In FIG. 11, the number of the first magnetic poles 40 is 64, and the number of the second magnetic poles 50 is 66.

[0127] The magnet member 3C includes a third track 9 in addition to the first track 4C and the second track 5C. The third track 9 has two third magnetic poles 91 and 92. The third magnetic pole 91 is a south magnetic pole, and the third magnetic pole 92 is a north magnetic pole. In other words, the number of pole pairs in the third track 9 is one.

[0128] When viewed in the longitudinal direction of the imaginary axis VA1, the shape of each of the two third magnetic poles 91, 92 is semi-annular. More specifically, the shape of each of the two third magnetic poles 91, 92 is semi-annular. Each of the two third magnetic poles 91, 92 surrounds half of the imaginary axis VA1. The centers C1 of the two third magnetic poles 91, 92, the substrate 30, the first track 4C, and the second track 5C are aligned.

[0129] When viewed from the longitudinal direction of the imaginary axis VA1, the third magnetic pole 91 is disposed outside the third magnetic pole 92. However, when viewed from the longitudinal direction of the imaginary axis VA1, the third magnetic pole 91 may be disposed inside the third magnetic pole 92.

[0130] The third track 9 is fixed to the substrate 30. This allows the third track 9, the first track 4C, and the second track 5C to rotate together in the detection direction D1.

[0131] When viewed in the longitudinal direction of the imaginary axis VA1, the third track 9 is disposed inside the substrate 30, the first track 4C, and the second track 5C. However, the arrangement of the third track 9 is not limited to this. The third track 9 may be disposed outside the substrate 30, the first track 4C, and the second track 5C, or may be disposed between the first track 4C and the second track 5C. The third track 9 may also be disposed on the surface of the substrate 30.

[0132] (3) Magnetic sensor The arrangement of the first sensor unit 61 and the second sensor unit 62 is the same as that of the third modification of the first embodiment (see FIG. 8), and therefore a description thereof will be omitted.

[0133] The magnetic sensor 6C has a determination sensor 65 in addition to the first sensor unit 61 and the second sensor unit 62. That is, the position detection system 1C is provided with the determination sensor 65. The determination sensor 65 has a function as a magnetic sensor (a function to detect magnetism). The determination sensor 65 generates and outputs determination information (output J4: see FIG. 13C) related to a determination of whether the absolute rotation angle of the rotational movement of the magnet member 3C (or the magnetic sensor 6C) is 0 to π (greater than or equal to 0 and less than π). The position where the absolute rotation angle is 0 may be defined arbitrarily. In this embodiment, the rotation angle is set to 0 when the determination sensor 65 is at one end 901 of the third track 9.

[0134] The determination sensor 65, the first sensor unit 61, and the second sensor unit 62 are aligned in the radial direction of the magnet member 3C. The determination sensor 65, the first sensor unit 61, and the second sensor unit 62 are fixed in position relative to one another. The determination sensor 65, the first sensor unit 61, and the second sensor unit 62 are housed in the same package. The determination sensor 65 includes, for example, at least one artificial lattice type GMR element. The structure of the GMR element of the determination sensor 65 may be similar to, for example, the GMR element 63 of the first sensor unit 61 and the second sensor unit 62 (see FIG. 4).

[0135] The determination sensor 65 detects the magnetism generated in the third track 9. When the absolute rotation angle of the rotational movement of the magnet member 3C including the third track 9 is equal to or greater than 0 and less than π, the determination sensor 65 is located on the surface of the third magnetic pole 91 (see FIG. 11). In other cases (when the absolute rotation angle is equal to or greater than π and less than 2π), the determination sensor 65 is located away from the third magnetic pole 91 (see FIG. 12). More specifically, when the absolute rotation angle is equal to or greater than π and less than 2π, the determination sensor 65 is in a state where no magnetic field is applied from the magnet member 3C.

[0136] Therefore, when the absolute rotation angle is equal to or greater than 0 and less than π, the determination sensor 65 outputs a first signal, and when the absolute rotation angle is equal to or greater than π and less than 2π, the determination sensor 65 outputs a second signal. The first signal corresponds to the magnetic field applied from the third magnetic pole 91. The second signal corresponds to the absence of a magnetic field. The second signal is different from the first signal. For example, the first signal is a voltage whose absolute value is equal to or greater than a predetermined value, and the second signal is a voltage whose absolute value is less than the predetermined value. Figure 13C illustrates the output J4 of the determination sensor 65 when the first signal is converted to a high signal and the second signal is converted to a low signal.

[0137] (4) Processing circuit The processing circuit 21 determines the first determination value J1 and the second determination value J2 by ​​the same processing as in embodiment 1. In the following, for simplicity of explanation, the number of first magnetic poles 40 is assumed to be four, and the number of second magnetic poles 50 is assumed to be two. The first determination value J1 and the second determination value J2 in this case are illustrated in FIGS. 13A and 13B.

[0138] 13A and 13B, the horizontal axis represents the absolute rotation angle of the magnet member 3C, and the vertical axis represents the first determination value J1 and the second determination value J2. The first determination value J1 and the second determination value J2 change in a sawtooth waveform.

[0139] As shown in FIG. 13A, when the absolute rotation angle of the magnet member 3C increases from 0 to π and from π to 2π, the first determination value J1 increases linearly from 0 to 2π.

[0140] As shown in Figure 13B, when the absolute rotation angle of the magnet member 3C increases from 0 to π / 2, when it increases from π / 2 to π, when it increases from π to 3π / 2, and when it increases from 3π / 2 to 2π, the second judgment value J2 increases linearly from 0 to 2π.

[0141] The processing circuit 21 calculates the third judgment value J3 by subtracting the second judgment value J2 from the first judgment value J1. As shown in Fig. 13B, when the absolute rotation angle of the magnet member 3C increases from π / 2 to 3π / 2, and when it increases from 3π / 2 to 2π (=0) and then to π / 2, the third judgment value J3 increases linearly from -π to π. Because the magnet member 3C has a two-fold symmetric shape, the third judgment value J3 repeats the same waveform every time the absolute rotation angle of the magnet member 3C changes by π.

[0142] 13C represents the absolute rotation angle of the magnet member 3C, and the vertical axis represents the output J4 of the determination sensor 65. As described above, when the absolute rotation angle of the magnet member 3C is equal to or greater than 0 and less than π, the determination sensor 65 outputs a first signal (High signal), and when the absolute rotation angle is equal to or greater than π and less than 2π, the determination sensor 65 outputs a second signal (Low signal).

[0143] The processing circuit 21 determines the absolute rotation angle of the magnetic sensor 6C relative to the magnet member 3C based on the output J4 of the determination sensor 65 and information regarding the phase of the output of the first sensor unit 61 and the phase of the output of the second sensor unit 62. In this embodiment, the information regarding the phase of the output of the first sensor unit 61 and the phase of the output of the second sensor unit 62 is the third determination value J3. As shown in FIG. 13B , when the absolute rotation angle of the magnet member 3C is in the range from 0 to π, the third determination value J3 corresponds one-to-one with the absolute rotation angle of the magnet member 3C (except for the rotation angles of 0, π / 2, and π). Furthermore, the waveform of the third determination value J3 is the same between the range of the absolute rotation angle of the magnet member 3C from 0 to π and the range of the absolute rotation angle of the magnet member 3C from π to 2π. Therefore, the absolute rotation angle of the magnetic sensor 6C relative to the magnet member 3C can be determined based on the output J4 of the determination sensor 65 and the third determination value J3. Specifically, the processing circuit 21 obtains the absolute rotation angle θ1 of the magnetic sensor 6C relative to the magnet member 3C using the following (Equation 5).

[0144] (Number 5) θ1=J3 / 2(0≦J3≦π, J4=High) θ1=π-|J3 / 2|(-π≦J3<0, J4=High) θ1=π+J3 / 2(0≦J3≦π, J4=Low) θ1=2π-|J3 / 2|(-π≦J3<0, J4=Low)

[0145] (5) Summary As described above, according to the position detection system 1C of this embodiment, the absolute rotation angle of the magnetic sensor 6C relative to the magnet member 3C can be obtained over the range of 0 to 2π.

[0146] (Modification 1 of Embodiment 2) The determination sensor 65 is not limited to a magnetic sensor. If the determination sensor 65 is not a magnetic sensor, the third track 9 can be omitted.

[0147] The determination sensor 65 may be, for example, an optical sensor. The optical sensor has, for example, a light-projecting unit and a light-receiving unit. When the absolute rotation angle of the rotational movement of the magnet member 3C is equal to or greater than 0 and less than π, or when the absolute rotation angle is otherwise, the light projected from the light-projecting unit is received by the light-receiving unit, and the optical sensor accordingly outputs a first signal. On the other hand, when the light projected from the light-projecting unit is blocked by an object (for example, the magnet member 3C), the amount of light received by the light-receiving unit is reduced, and the optical sensor accordingly outputs a second signal.

[0148] The determination sensor 65 may also be a contact-type position sensor. The contact-type position sensor has a brush. When the absolute rotation angle of the rotational movement of the magnet member 3C is equal to or greater than 0 and less than π, or when the absolute rotation angle is otherwise, the brush comes into contact with the conductor, and in response, the contact-type position sensor produces a first output. When the brush comes out of contact with the conductor, in response, the contact-type position sensor produces a second output.

[0149] The determination sensor 65 may also be a capacitance sensor. The capacitance sensor has two conductors. The capacitance between the two conductors differs depending on whether the absolute rotation angle of the rotational movement of the magnet member 3C is greater than or equal to 0 and less than π or otherwise, and the capacitance sensor outputs an output corresponding to the capacitance between the two conductors. More specifically, the capacitance sensor outputs a first output when the absolute rotation angle of the rotational movement of the magnet member 3C is greater than or equal to 0 and less than π or otherwise, and outputs a second output when the absolute rotation angle is greater than or equal to 0 and less than π or otherwise.

[0150] (Modification 2 of Embodiment 2) The difference between the first and second magnetic pole numbers is not limited to 2. When the difference is 2N (N is a natural number greater than or equal to 2), the third determination value J3 repeats the same waveform every time the absolute rotation angle of the magnet member 3C changes by 2π / 2N. Therefore, for example, the output J4 of the determination sensor 65 may be switched every time the absolute rotation angle of the magnet member 3C changes by 2π / 2N. The output J4 of the determination sensor 65 may be expressed as at least 2N values. In this case, the output J4 is an output that can distinguish whether the absolute rotation angle of the magnet member 3C relative to the magnetic sensor 6C is within a first range (here, 0 to 2π / 2N), a second range (here, 2π / 2N to 4π / 2N), a third range (here, 4π / 2N to 6π / 2N), etc. In this case, the processing circuit 21 can determine the absolute rotation angle of the magnet member 3C based on the output J4 of the determination sensor 65 and the third determination value J3.

[0151] (Other Modifications of the Second Embodiment) Other variations of the second embodiment are listed below. The following variations may be implemented in appropriate combinations. The following variations may also be implemented in appropriate combinations with the above-described variations of the second embodiment.

[0152] Each of the modifications of the first embodiment may be applied to the second embodiment as appropriate.

[0153] The position of the first track 4C and the position of the second track 5C may be different in the longitudinal direction of the imaginary axis VA1. For example, the first track 4C and the second track 5C may be arranged similarly to Modification 4 of Embodiment 1 (see FIG. 10). In this case, the third track 9 is attached to the shaft 83, and the first track 4C, the second track 5C, and the third track 9 rotate integrally around the shaft 83.

[0154] In this embodiment, 0 to π has been described as meaning "0 or more and less than π", but "more than or equal to" may be "greater than". There is no technical difference between "more than or equal to" and "greater than". Similarly, "less than" may be "less than or equal to".

[0155] In this embodiment, when the absolute rotation angle of the rotational movement of the magnet member 3C is equal to or greater than 0 and less than π, the determination sensor 65 is located on the surface of the third magnetic pole 91 (see FIG. 11). However, when the absolute rotation angle of the rotational movement of the magnet member 3C is equal to or greater than 0 and less than π, the determination sensor 65 may be located on the surface of the third magnetic pole 92.

[0156] (summary) The above-described embodiments and the like disclose the following aspects.

[0157] The position detection circuit (2) according to the first aspect includes a processing circuit (21). The processing circuit (21) processes the output of a magnetic sensor (6, 6C). The magnetic sensor (6, 6C) detects a magnetic field generated by a magnet member (3, 3A, 3B, 3C). The magnet member (3, 3A, 3B, 3C) includes a first track (4, 4A, 4B, 4C) having a plurality of first magnetic poles (40) and a second track (5, 5A, 5B, 5C) having a plurality of second magnetic poles (50). The plurality of first magnetic poles (40) and the plurality of second magnetic poles (50) are each a plurality of magnetic poles in which north poles and south poles are alternately arranged in a predetermined detection direction (D1). The magnetic pole pitch (P1) of the plurality of first magnetic poles (40) in the detection direction (D1) is different from the magnetic pole pitch (P2) of the plurality of second magnetic poles (50) in the detection direction (D1). The magnetic sensor (6, 6C) has a first sensor unit (61) that detects the magnetic field generated in the first track (4, 4A, 4B, 4C) and a second sensor unit (62) that detects the magnetic field generated in the second track (5, 5A, 5B, 5C). At least one of the magnetic sensor (6, 6C) and the magnet member (3, 3A, 3B, 3C) moves along the detection direction (D1) relative to the other. The processing circuit (21) determines the position of the magnetic sensor (6, 6C) relative to the magnet member (3, 3A, 3B, 3C) based on information regarding the phase of the output of the first sensor unit (61) and the phase of the output of the second sensor unit (62).

[0158] According to the above configuration, the resolution of position detection can be improved compared to when the processing circuit (21) performs position detection without using information regarding the phase of the output of the first sensor unit (61) and the phase of the output of the second sensor unit (62).

[0159] In addition, in the position detection circuit (2) according to the second aspect, in the first aspect, the magnet member (3, 3A, 3B) includes a detection area (R1) facing the magnetic sensor (6). The first number of magnetic poles and the second number of magnetic poles are prime to each other. The first number of magnetic poles is the number of magnetic poles among the multiple first magnetic poles (40) that are arranged within the detection area (R1). The second number of magnetic poles is the number of magnetic poles among the multiple second magnetic poles (50) that are arranged within the detection area (R1).

[0160] According to the above configuration, the absolute position of the magnetic sensor (6) can be detected in a wider range than when the first number of magnetic poles and the second number of magnetic poles are not coprime.

[0161] In the position detection circuit (2) according to the third aspect, in the second aspect, the difference between the first number of magnetic poles and the second number of magnetic poles is smaller than the smaller of the first number of magnetic poles and the second number of magnetic poles.

[0162] According to the above configuration, it is possible to reduce the influence of the second magnetic pole (50) on the magnetic field around the first magnetic pole (40). Also, it is possible to reduce the influence of the first magnetic pole (40) on the magnetic field around the second magnetic pole (50). This improves the accuracy of position detection.

[0163] In addition, in the position detection circuit (2) according to the fourth aspect, in any one of the first to third aspects, the processing circuit (21) determines the position of the magnetic sensor (6, 6C) relative to the magnet member (3, 3A, 3B, 3C) based on a value (third determination value (J3)) corresponding to the difference between the first determination value (J1) based on the output of the first sensor section (61) and the second determination value (J2) based on the output of the second sensor section (62).

[0164] According to the above configuration, the processing circuit (21) can determine the positions of the magnetic sensors (6, 6C) through simple processing.

[0165] In addition, in a position detection circuit (2) according to a fifth aspect, in any one of the first to fourth aspects, the first sensor unit (61) corresponds to the first track (4, 4A, 4B, 4C) and the second sensor unit (62) corresponds to the second track (5, 5A, 5B, 5C). The processing circuit (21) determines the position of the magnetic sensor (6, 6C) relative to the magnet member (3, 3A, 3B, 3C) with a resolution according to the resolution of the output of the sensor unit corresponding to the track with the smaller magnetic pole pitch between the first track (4, 4A, 4B, 4C) and the second track (5, 5A, 5B, 5C).

[0166] According to the above configuration, the resolution can be improved compared to when a resolution corresponding to the output resolution of the sensor unit corresponding to the track with the smaller magnetic pole pitch is adopted, which means that the resolution of position detection can be further improved.

[0167] In addition, in the position detection circuit (2) according to the sixth aspect, in any one of the first to fifth aspects, in a Cartesian coordinate system in which the coordinate axes representing the coordinates of the first sensor unit (61) and the second sensor unit (62) in the detection direction (D1) and the coordinate axes representing the outputs of the first sensor unit (61) and the second sensor unit (62) are orthogonal to each other, the output waveforms of each of the first sensor unit (61) and the second sensor unit (62) are sinusoidal.

[0168] According to the above configuration, it is easy to associate the outputs of the first sensor (61) and the second sensor (62) with the positions of the magnetic sensors (6, 6C), thereby improving the accuracy of position detection.

[0169] In addition, in a position detection circuit (2) according to a seventh aspect, in any one of the first to sixth aspects, the first track (4C) and the second track (5C) each have an annular shape surrounding a common imaginary axis (VA1). At least one of the magnetic sensor (6C) and the magnet member (3C) rotates relative to the other along a detection direction (D1). The detection direction (D1) is a direction around the imaginary axis (VA1). The determination sensor (65) generates determination information (output J4). The determination information is information related to whether the absolute rotation angle of the rotation is between 0 and π. The processing circuit (21) calculates the absolute rotation angle of the magnetic sensor (6C) relative to the magnet member (3C) based on the determination information output from the determination sensor (65) and information related to the phase of the output of the first sensor unit (61) and the phase of the output of the second sensor unit (62).

[0170] According to the above configuration, the absolute rotation angle of the magnetic sensor (6C) relative to the magnet member (3C) can be obtained over the range of 0 to 2π.

[0171] The configurations other than those of the first aspect are not essential for the position detection circuit (2) and can be omitted as appropriate.

[0172] A position detection system (1, 1C) according to an eighth aspect includes a position detection circuit (2) according to any one of the first to sixth aspects, a magnet member (3, 3A, 3B, 3C), and a magnetic sensor (6, 6C).

[0173] According to the above configuration, the resolution of position detection can be improved.

[0174] A position detection system (1C) according to a ninth aspect includes the position detection circuit (2) according to the seventh aspect, a magnet member (3C), a magnetic sensor (6C), and a determination sensor (65). The determination sensor (65) produces a first output when the absolute rotation angle of the rotational movement is between 0 and π, and produces a second output different from the first output in other cases.

[0175] According to the above configuration, the absolute rotation angle of the magnetic sensor (6C) relative to the magnet member (3C) can be obtained over the range of 0 to 2π.

[0176] In a position detection system (1C) according to a tenth aspect, in the ninth aspect, the magnet member (3C) includes a third track (9). The third track (9) has third magnetic poles (91, 92). The magnetic sensor (6C) has a determination sensor (65). The determination sensor (65) detects magnetism generated in the third track (9).

[0177] According to the above configuration, the magnetic sensor (6C) can constitute the determination sensor (65), the first sensor (61), and the second sensor (62).

[0178] In addition, in a position detection system (1C) according to an eleventh aspect, in the ninth or tenth aspect, the difference between the number of first magnetic poles (40) and the number of second magnetic poles (50) is two.

[0179] According to the above configuration, the period of the combined signal (third determination value J3) of the outputs of the first sensor part (61) and the second sensor part (62) can be made longer than when the difference is greater than two.

[0180] In addition, in the position detection system (1) according to the twelfth aspect, in the eighth aspect, the shape of the magnet member (3) is linear.

[0181] According to the above configuration, the position detection system (1) can be used as a linear encoder.

[0182] In addition, in the position detection system (1, 1C) according to the thirteenth aspect, in the eighth aspect, the shape of the magnet member (3A, 3B, 3C) is arc-shaped or annular.

[0183] According to the above configuration, the position detection system (1, 1C) can detect the rotational movement.

[0184] In addition, in a position detection system (1, 1C) according to a fourteenth aspect, in any one of the eighth to thirteenth aspects, the magnetic sensor (6, 6C) includes a plurality of first sensor units (61) and a plurality of second sensor units (62). The plurality of first sensor units (61) are aligned in the detection direction (D1). The plurality of second sensor units (62) are aligned in the detection direction (D1).

[0185] According to the above configuration, the accuracy of position detection can be improved compared to when the magnetic sensor (6, 6C) has only one first sensor portion (61) and one second sensor portion (62).

[0186] In addition, in a position detection system (1, 1C) according to a fifteenth aspect, in any one of the eighth to fourteenth aspects, each of the first sensor section (61) and the second sensor section (62) includes an artificial lattice type GMR element (63).

[0187] According to the above configuration, the output waveform of the GMR element (63) is relatively stable, and therefore the accuracy of position detection can be improved.

[0188] In addition, in a position detection system (1, 1C) according to a sixteenth aspect, in the fifteenth aspect, the GMR element (63) has a layered structure (640) containing cobalt and iron.

[0189] According to the above configuration, the output of the GMR element (63) can be made relatively large.

[0190] The configurations other than the eighth aspect are not essential for the position detection system (1, 1C) and can be omitted as appropriate.

[0191] Moreover, the magnet member (3, 3A, 3B, 3C) according to the seventeenth aspect is used in the position detection system (1, 1C) according to any one of the eighth to sixteenth aspects.

[0192] According to the above configuration, the resolution of position detection can be improved.

[0193] A position detection method according to an eighteenth aspect includes a processing step. In the processing step, an output of a magnetic sensor (6, 6C) is processed. The magnetic sensor (6, 6C) detects a magnetism generated by a magnet member (3, 3A, 3B, 3C). The magnet member (3, 3A, 3B, 3C) includes a first track (4, 4A, 4B, 4C) having a plurality of first magnetic poles (40) and a second track (5, 5A, 5B, 5C) having a plurality of second magnetic poles (50). The plurality of first magnetic poles (40) and the plurality of second magnetic poles (50) are each a plurality of magnetic poles in which north poles and south poles are alternately arranged in a predetermined detection direction (D1). A magnetic pole pitch (P1) of the plurality of first magnetic poles (40) in the detection direction (D1) is different from a magnetic pole pitch (P2) of the plurality of second magnetic poles (50) in the detection direction (D1). The magnetic sensors (6, 6C) have a first sensor unit (61) that detects the magnetism generated in the first tracks (4, 4A, 4B, 4C) and a second sensor unit (62) that detects the magnetism generated in the second tracks (5, 5A, 5B, 5C). At least one of the magnetic sensors (6, 6C) and the magnet members (3, 3A, 3B, 3C) moves along a detection direction (D1) relative to the other. In a processing step, the position of the magnetic sensors (6, 6C) relative to the magnet members (3, 3A, 3B, 3C) is determined based on information regarding the phase of the output of the first sensor unit (61) and the phase of the output of the second sensor unit (62).

[0194] According to the above configuration, the resolution of position detection can be improved.

[0195] A program according to a nineteenth aspect is a program for causing one or more processors to execute the position detection method according to the eighteenth aspect.

[0196] According to the above configuration, the resolution of position detection can be improved.

[0197] Not limited to the above-described aspects, various configurations (including modified examples) of the position detection circuit (2) and the position detection system (1, 1C) according to the embodiment can be realized as a position detection method and a program. [Explanation of symbols]

[0198] 1. 1C position detection system 2 Position detection circuit 21 Processing circuit 3, 3A, 3B, 3C magnet parts 4, 4A, 4B, 4C Track 1 40 1st magnetic pole 5, 5A, 5B, 5C Track 2 50 2nd magnetic pole 6, 6C magnetic sensor 61 First sensor section 62 Second sensor section 63 GMR element 640 Laminated structure 65 Judgment sensor 9. Third Track 91, 92 3rd magnetic pole D1 Detection direction J1 First judgment value J2 Second judgment value J4 output (judgment information) P1 Pole pitch P2 magnetic pole pitch R1 detection area VA1 Virtual axis

Claims

1. a processing circuit for processing an output of a magnetic sensor that detects a magnetic field generated by a magnet member including a first track having a plurality of first magnetic poles and a second track having a plurality of second magnetic poles; the plurality of first magnetic poles and the plurality of second magnetic poles are each a plurality of magnetic poles in which N poles and S poles are alternately arranged in a predetermined detection direction, a magnetic pole pitch of the plurality of first magnetic poles in the detection direction is different from a magnetic pole pitch of the plurality of second magnetic poles in the detection direction; the magnetic sensor has two first sensor units and two second sensor units, each of the two first sensor units detects a magnetism generated in the first track; each of the two second sensor units detects a magnetism generated in the second track; At least one of the magnetic sensor and the magnet member moves along the detection direction relative to the other, the two first sensor units include one first sensor unit and the other first sensor unit, the two second sensor units include one second sensor unit and the other second sensor unit, The processing circuitry determining a position of the magnetic sensor relative to the magnet member based on information regarding a phase of the output of each of the two first sensor units and a phase of the output of each of the two second sensor units; determining that at least one of the first sensor units is abnormal when a difference between the output of the one first sensor unit when the one first sensor unit is in a first predetermined position and the output of the other first sensor unit when the other first sensor unit is in the first predetermined position is equal to or greater than a first predetermined value; determining that at least one of the second sensor units is abnormal when a difference between the output of the one second sensor unit when the one second sensor unit is in a second predetermined position and the output of the other second sensor unit when the other second sensor unit is in the second predetermined position is equal to or greater than a second predetermined value; Position sensing circuit.

2. the magnet member includes a detection area facing the magnetic sensor, a first magnetic pole number, which is the number of magnetic poles among the plurality of first magnetic poles that are arranged within the detection area, and a second magnetic pole number, which is the number of magnetic poles among the plurality of second magnetic poles that are arranged within the detection area, are coprime to each other; 2. The position sensing circuit of claim 1.

3. a difference between the first number of magnetic poles and the second number of magnetic poles is smaller than the smaller of the first number of magnetic poles and the second number of magnetic poles; 3. The position sensing circuit of claim 2.

4. the processing circuit determines a position of the magnetic sensor relative to the magnet member based on a value corresponding to a difference between a first determination value based on the output of the first sensor unit and a second determination value based on the output of the second sensor unit. The position detection circuit according to any one of claims 1 to 3.

5. the first sensor unit corresponds to the first track, and the second sensor unit corresponds to the second track; the processing circuit determines the position of the magnetic sensor relative to the magnet member with a resolution corresponding to the resolution of the output of the sensor unit corresponding to the track having the smaller magnetic pole pitch out of the first track and the second track. The position detection circuit according to any one of claims 1 to 4.

6. In an orthogonal coordinate system in which coordinate axes representing coordinates of the first sensor unit and the second sensor unit in the detection direction and coordinate axes representing the outputs of the first sensor unit and the second sensor unit are orthogonal to each other, output waveforms of the first sensor unit and the second sensor unit are sinusoidal. The position detection circuit according to any one of claims 1 to 5.

7. each of the first track and the second track has an annular shape surrounding a common imaginary axis; At least one of the magnetic sensor and the magnet member rotates relative to the other along the detection direction, which is a direction of rotation around the virtual axis, the processing circuit determines an absolute rotation angle of the magnetic sensor relative to the magnet member based on determination information output from a determination sensor that generates determination information related to whether or not the absolute rotation angle of the rotational movement is between 0 and π, and the information related to the phase of the output of each of the two first sensor units and the phase of the output of each of the two second sensor units; The position detection circuit according to any one of claims 1 to 6.

8. A position detection circuit according to any one of claims 1 to 6; The magnet member; The magnetic sensor, Position sensing system.

9. a position detection circuit according to claim 7; The magnet member; the magnetic sensor; The determination sensor, the determination sensor outputs a first output when the absolute rotation angle of the rotational movement is between 0 and π, and outputs a second output different from the first output in other cases; Position sensing system.

10. the magnet member includes a third track having a third magnetic pole; the magnetic sensor includes the determination sensor that detects the magnetism generated in the third track; The position detection system of claim 9.

11. a difference between the number of the first magnetic poles and the number of the second magnetic poles is 2; 11. A position detection system according to claim 9 or 10.

12. The shape of the magnet member is linear. The position detection system of claim 8 .

13. The shape of the magnet member is arc-shaped or annular. The position detection system of claim 8 .

14. the magnetic sensor includes a plurality of the first sensor units and a plurality of the second sensor units, the plurality of first sensor units are aligned in the detection direction, The plurality of second sensor units are aligned in the detection direction. A position detection system according to any one of claims 8 to 13.

15. each of the first sensor unit and the second sensor unit includes an artificial lattice type GMR element; A position detection system according to any one of claims 8 to 14.

16. the GMR element has a layered structure containing cobalt and iron; 16. The position detection system of claim 15.

17. A method for detecting a magnetic field generated by a magnetic member including a first track having a plurality of first magnetic poles and a second track having a plurality of second magnetic poles, the method comprising: a processing step for processing an output of a magnetic sensor that detects a magnetic field generated by a magnetic member including a first track having a plurality of first magnetic poles and a second track having a plurality of second magnetic poles; the plurality of first magnetic poles and the plurality of second magnetic poles are each a plurality of magnetic poles in which N poles and S poles are alternately arranged in a predetermined detection direction, a magnetic pole pitch of the plurality of first magnetic poles in the detection direction is different from a magnetic pole pitch of the plurality of second magnetic poles in the detection direction; the magnetic sensor has two first sensor units and two second sensor units, each of the two first sensor units detects a magnetism generated in the first track; each of the two second sensor units detects a magnetism generated in the second track; At least one of the magnetic sensor and the magnet member moves along the detection direction relative to the other, the two first sensor units include one first sensor unit and the other first sensor unit, the two second sensor units include one second sensor unit and the other second sensor unit, In the processing step, determining a position of the magnetic sensor relative to the magnet member based on information regarding a phase of the output of each of the two first sensor units and a phase of the output of each of the two second sensor units; determining that at least one of the first sensor units is abnormal when a difference between the output of the one first sensor unit when the one first sensor unit is in a first predetermined position and the output of the other first sensor unit when the other first sensor unit is in the first predetermined position is equal to or greater than a first predetermined value; determining that at least one of the second sensor units is abnormal when a difference between the output of the one second sensor unit when the one second sensor unit is in a second predetermined position and the output of the other second sensor unit when the other second sensor unit is in the second predetermined position is equal to or greater than a second predetermined value; Position sensing method.

18. For causing one or more processors to execute the position detection method according to claim 17, program.

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