JP2019143991A - Magnetic sensor system and magnetic scale - Google Patents

Abstract

To achieve high detection accuracy concerning a magnetic sensor system including a magnetic scale and a magnetic sensor.SOLUTION: A magnetic sensor system 1 includes: a magnetic scale 2 for generating an external magnetic field; and a magnetic sensor 3 for detecting an applied magnetic field being a part of an external magnetic field. The magnetic scale 2 includes: multiple main magnets 11-13 for generating a main magnetic field; and multiple sub-magnets 21-24, 31-38 for generating a sub-magnetic field. When an angle made by a direction of an applied magnetic field with respect to a reference direction is defined as an applied magnetic field angle, an ideal change of an applied magnetic field angle with respect to a change of a relative position of the magnetic scale 2 with respect to the magnetic sensor 3 is expressed as an ideal straight line. A sub-magnetic field corrects a main magnetic field so as to allow the maximum deviation from an ideal straight line in a characteristic curve expressing a change of an applied magnetic field angle with respect to a change of a relative position to be smaller compared with a case where an external magnetic field consists of only a main magnetic field.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a magnetic sensor system including a magnetic scale and a magnetic sensor, and a magnetic scale used in the magnetic sensor system.

  A magnetic sensor system including a magnetic scale and a magnetic sensor is used, for example, to detect the position of a movable object whose position changes in a linear direction or a rotational direction. A magnetic sensor system used for detecting the position of a movable object is configured such that the relative position of the magnetic scale with respect to the magnetic sensor changes within a predetermined range in response to a change in the position of the movable object. .

  The magnetic scale includes, for example, a plurality of magnets arranged along a linear direction or a rotational direction. The magnetization directions of the plurality of magnets are set so as to be switched alternately. When the relative position of the magnetic scale with respect to the magnetic sensor changes, the direction of the magnetic field generated by the magnetic scale and applied to the magnetic sensor rotates. For example, the magnetic sensor generates a detection value having a correspondence relationship with an angle formed by the direction of the applied magnetic field with respect to the reference direction (hereinafter referred to as an applied magnetic field angle).

  Patent Document 1 describes a position detection device including a magnetic sensing element and a plurality of magnetic members whose magnetic pole surfaces are arranged to face the magnetic sensing element. The magnetic sensing element corresponds to the magnetic sensor. The plurality of magnetic members correspond to the plurality of magnets. In this position detection apparatus, adjacent magnetic members are arranged so that the magnetic pole surfaces on the side facing the magnetic sensing element are opposite to each other and are spaced apart from each other.

Japanese Patent No. 5013146

  In the magnetic sensor system, in order to realize high detection accuracy, it is desirable that the change in the applied magnetic field angle with respect to the change in the relative position of the magnetic scale is linear.

  However, in practice, the change in the applied magnetic field angle with respect to the change in the relative position of the magnetic scale is not linear, and as a result, an error may occur in the detection value of the magnetic sensor.

  The shape of the characteristic curve representing the change in the applied magnetic field angle with respect to the change in the relative position of the magnetic scale changes depending on the arrangement pitch of the plurality of magnets in the magnetic scale and the size of the interval between the magnetic scale and the magnetic sensor.

  The present invention has been made in view of the above problems, and an object of the present invention is a magnetic sensor system including a magnetic scale and a magnetic sensor, which can realize high detection accuracy, and the magnetic sensor. It is to provide a magnetic scale used in the system.

  The magnetic sensor system of the present invention includes the magnetic scale of the present invention and a magnetic sensor. The magnetic scale generates an external magnetic field having a spatial distribution of intensity and direction. The magnetic sensor detects an applied magnetic field that is a part of the external magnetic field, and generates a detection value corresponding to applied magnetic field information that is information that the applied magnetic field has.

  The magnetic scale includes a plurality of main magnets that generate a main magnetic field and a plurality of submagnets that generate a sub-magnetic field. The plurality of main magnets are arranged at intervals along a first direction which is a linear direction or a rotational direction. The external magnetic field is a combination of a main magnetic field and a sub magnetic field.

  The relative position of the magnetic scale with respect to the magnetic sensor can be changed within a predetermined range along the first direction. When the ideal change in the applied magnetic field information with respect to the change in the relative position is regarded as an ideal characteristic, the sub magnetic field has a change in the applied magnetic field information with respect to the change in the relative position as compared with the case where the external magnetic field is composed only of the main magnetic field. The main magnetic field is corrected so that the characteristic to be expressed approaches the ideal characteristic.

  In the magnetic sensor system and the magnetic scale of the present invention, the plurality of submagnets may be arranged at positions different from the plurality of main magnets along the first direction. In this case, the plurality of submagnets may be arranged such that two or more submagnets exist between two adjacent main magnets among the plurality of main magnets.

  In the magnetic sensor system and the magnetic scale of the present invention, the magnetic sensor may be located at a position away from the magnetic scale in the second direction. In this case, each of the plurality of main magnets and the plurality of submagnets may have magnetization in a direction parallel to the second direction.

  Further, in the magnetic sensor system and the magnetic scale of the present invention, when the external magnetic field consists only of the main magnetic field, the component of the unidirectional component of the applied magnetic field with respect to the change in the relative position when n is an integer of 2 or more The curve representing the change in intensity may include an ideal component that draws a sine curve and at least one harmonic component corresponding to the (2n-1) th order harmonic of the ideal component. Moreover, the some submagnet may comprise the group of 1 or more sets of submagnets. Each set of sub-magnets may be for correcting the main magnetic field so that one harmonic component is reduced.

  Further, the plurality of main magnets may be arranged at a constant interval D along the first direction. In this case, when m is an integer greater than or equal to 1, each of the sub magnets in each set is a position between two adjacent main magnets of the plurality of main magnets, May be arranged at a position different from that of the main magnet by m × {1 / (2n−1)} × D in the first direction.

  Moreover, the magnetization directions of two adjacent main magnets among the plurality of main magnets may be opposite to each other. Moreover, the direction of the magnetization of the submagnet arrange | positioned in the position where m becomes 1 among each group of submagnets may be the same as the magnetization direction of the main magnet nearest to the submagnet.

  Further, among the secondary magnets in each set, the direction of magnetization of the secondary magnet arranged at a position where m is 2 or more is opposite to the direction of magnetization of each of the two secondary magnets in the same set on both sides of the secondary magnet. It may be.

  In the magnetic sensor system of the present invention, the range of the detection value may be a range in which the relative position can be uniquely specified.

  In the magnetic sensor system and the magnetic scale of the present invention, the applied magnetic field information may be an angle formed by the direction of the applied magnetic field with respect to the reference direction. Alternatively, the applied magnetic field information may be the intensity of a component in one direction of the applied magnetic field.

  According to the magnetic sensor system and the magnetic scale of the present invention, the main magnetic field generated by the plurality of main magnets is corrected by the sub-magnetic field generated by the plurality of sub-magnets, thereby achieving high detection accuracy in the magnetic sensor system. There is an effect that it can be realized.

1 is a perspective view showing a schematic configuration of a magnetic sensor system according to a first embodiment of the present invention. It is explanatory drawing for demonstrating the reference direction in the 1st Embodiment of this invention. It is explanatory drawing for demonstrating arrangement | positioning and the direction of magnetization of a main magnet and a submagnet in the 1st Embodiment of this invention. It is a perspective view which shows the 1st example of the magnetic sensor in the 1st Embodiment of this invention. It is a circuit diagram which shows the structure of the 1st example of the magnetic sensor in the 1st Embodiment of this invention. It is a perspective view which shows the 2nd example of the magnetic sensor in the 1st Embodiment of this invention. It is a circuit diagram which shows the structure of the 2nd example of the magnetic sensor in the 1st Embodiment of this invention. It is a characteristic view which shows the main magnetic flux density corresponding to the main magnetic field in the 1st Embodiment of this invention. It is a characteristic view which shows the 1st sub magnetic flux density corresponding to the 1st sub magnetic field component in the 1st Embodiment of this invention. It is a characteristic view which shows the 2nd sub magnetic flux density corresponding to the 2nd sub magnetic field component in the 1st Embodiment of this invention. It is a characteristic view which shows the applied magnetic flux density corresponding to the applied magnetic field in the 1st Embodiment of this invention. It is a perspective view which shows the magnetic scale of a 1st comparative example. It is a characteristic view which shows the applied magnetic flux density of the 1st comparative example corresponding to the applied magnetic field of a 1st comparative example. It is a characteristic view which shows the detection value characteristic curve of the 1st comparative example. It is a characteristic view which shows the angle error of the 1st comparative example. It is a characteristic view which shows the detection value characteristic curve in the 1st Example of the 1st Embodiment of this invention. It is a characteristic view which shows the angle error in the 1st Example of the 1st Embodiment of this invention. It is a perspective view which shows the magnetic scale which concerns on the 2nd Embodiment of this invention. It is a perspective view which shows the magnetic scale which concerns on the 3rd Embodiment of this invention. It is a perspective view which shows the magnetic sensor system which concerns on the 4th Embodiment of this invention. It is explanatory drawing for demonstrating arrangement | positioning and the direction of magnetization of a main magnet and a submagnet in the 4th Embodiment of this invention. It is a circuit diagram which shows the structure of the 1st example of the magnetic sensor in the 5th Embodiment of this invention. It is a perspective view which shows the 2nd example and magnetic scale of the magnetic sensor in the 5th Embodiment of this invention. It is a characteristic view which shows the applied magnetic flux density of the 2nd comparative example corresponding to the applied magnetic field of a 2nd comparative example. It is a characteristic view which shows the applied magnetic flux density corresponding to the applied magnetic field in the 5th Embodiment of this invention.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, a schematic configuration of a magnetic sensor system according to a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the magnetic sensor system 1 according to the present embodiment includes a magnetic scale 2 and a magnetic sensor 3. The magnetic scale 2 generates an external magnetic field having a spatial distribution of intensity and direction. The magnetic sensor 3 detects an applied magnetic field that is a part of the external magnetic field, and generates a detection value θs corresponding to applied magnetic field information that is information that the applied magnetic field has. In the present embodiment, the applied magnetic field information is an angle formed by the direction of the applied magnetic field with respect to the reference direction. Hereinafter, an angle formed by the direction of the applied magnetic field with respect to the reference direction is referred to as an applied magnetic field angle and is represented by the symbol θM. The detected value θs has a corresponding relationship with the applied magnetic field angle θM. The reference direction will be described later.

  The magnetic scale 2 includes a plurality of main magnets that generate a main magnetic field, a plurality of submagnets that generate a submagnetic field, a substrate 61 that supports the plurality of main magnets and the plurality of submagnets, a plurality of main magnets, and a plurality of submagnets. And a protection part 62 that protects the secondary magnet. The protection unit 62 is shown in FIG. 3 described later. The protection part 62 is made of, for example, resin and covers the plurality of main magnets and the plurality of sub magnets. The external magnetic field is a combination of a main magnetic field and a sub magnetic field. The plurality of main magnets and the plurality of submagnets have, for example, a rectangular parallelepiped shape.

  In the present embodiment, the magnetic scale 2 is a linear scale. The substrate 61 has a plate shape that is long in one direction. The substrate 61 has an upper surface 61a and a lower surface 61b. The plurality of main magnets and the plurality of submagnets are disposed on the upper surface 61 a of the substrate 61. The magnetic sensor 3 is disposed so as to face the upper surface 61 a of the substrate 61.

  Here, as shown in FIG. 1, an X direction, a Y direction, and a Z direction are defined. In the present embodiment, the direction perpendicular to the upper surface 61a of the substrate 61 and from the lower surface 61b to the upper surface 61a is defined as the Z direction. Further, two directions perpendicular to the Z direction and orthogonal to each other are defined as an X direction and a Y direction. In addition, a direction opposite to the X direction is defined as -X direction, a direction opposite to the Y direction is defined as -Y direction, and a direction opposite to the Z direction is defined as -Z direction.

  In the present embodiment, a direction parallel to the X direction is referred to as a first direction and is represented by reference numeral X1. The first direction X1 is a linear direction. The first direction X1 includes an X direction and a −X direction. The plurality of main magnets are arranged at intervals along the first direction X1. The plurality of submagnets are arranged at positions different from the plurality of main magnets along the first direction X1.

  Here, the positions of the plurality of main magnets and the plurality of submagnets in the first direction X1 are defined as follows. First, a straight line that is located on the upper surface 61a of the substrate 61 and extends in the first direction X1 and that is in contact with the plurality of main magnets and the plurality of submagnets is defined as a position reference line. Then, among the position reference lines, the position of the midpoint of the line segment that overlaps each of the plurality of main magnets and the plurality of submagnets is defined as the position in the first direction X1 of each of the plurality of main magnets and the plurality of submagnets. To do.

  In the present embodiment, the Z direction corresponds to the second direction in the present invention. The magnetic sensor 3 is located away from the magnetic scale 2 in the Z direction (second direction). Each of the plurality of main magnets and the plurality of submagnets has magnetization in a direction parallel to the Z direction (second direction). The arrangement of the plurality of main magnets and the plurality of sub magnets and the direction of magnetization will be described in detail later.

  The relative position of the magnetic scale 2 with respect to the magnetic sensor 3 can be changed within a predetermined range along the first direction X1. Hereinafter, the relative position of the magnetic scale 2 with respect to the magnetic sensor 3 is referred to as a relative position P2. In the present embodiment, one of the magnetic scale 2 and the magnetic sensor 3 moves linearly in the X direction or the −X direction in conjunction with a movable object (not shown). As a result, the relative position P2 changes in the X direction or the -X direction. The applied magnetic field angle θM changes as the relative position P2 changes.

  The magnetic sensor system 1 according to the present embodiment can be used as a position detection device for detecting the relative position P2. The detected value θs has a corresponding relationship with the relative position P2. When the magnetic sensor system 1 is used as a position detection device, the range of the detection value θs may be a range in which the relative position P2 can be uniquely specified. Such a range of the detected value θs is a range in which the detected value θs does not become the same value at a plurality of relative positions P2. This is, for example, a range narrower than 0 ° to 360 °. In order to make the range of the detected value θs narrower than 0 ° to 360 °, a predetermined range in which the relative position P2 can be changed (hereinafter referred to as a movable range) is set to 0 ° to 360 ° of the detected value θs. The range of the detected value θs actually generated by the magnetic sensor 3 is limited to a range narrower than 0 ° to 360 °, and the relative position corresponding to the limited range of the detected value θs. Only the range of P2 may be the range of the relative position P2 that can be detected. Alternatively, the movable range may be a range narrower than the range in which the detection value θs is 0 ° to 360 °. Accordingly, the relative position P2 can be uniquely specified by the detected value θs.

  Next, a reference direction in the present embodiment will be described with reference to FIG. Here, the reference position where the magnetic sensor 3 detects the applied magnetic field is referred to as a reference position PR. The reference position PR is a position in the magnetic sensor 3. The XZ plane including the reference position PR is referred to as a reference plane P. As shown in FIG. 2, in the reference plane P, the direction DM of the applied magnetic field rotates around the reference position PR. In the following description, the direction DM of the applied magnetic field refers to a direction located in the reference plane P.

  The reference direction DR is located in the reference plane P. In the present embodiment, the Z direction is the reference direction DR. The angle formed by the direction DM of the applied magnetic field with respect to the reference direction DR, that is, the applied magnetic field angle θM, is represented by a positive value when viewed counterclockwise from the reference direction DR, and is viewed clockwise from the reference direction DR. When a negative value is used.

  Next, the arrangement of the plurality of main magnets and the plurality of submagnets and the direction of magnetization will be described with reference to FIG. First, the arrangement of a plurality of main magnets and a plurality of submagnets will be described. In the present embodiment, the magnetic scale 2 includes three main magnets 11, 12, and 13 as a plurality of main magnets. The main magnets 11, 12, and 13 are arranged at a constant interval D in this order along the first direction X1.

  The plurality of submagnets constitute one or more sets of submagnets. In the present embodiment, the magnetic scale 2 includes, as a plurality of submagnets, four submagnets 21, 22, 23, and 24 that constitute the first set, and eight submagnets 31 that constitute the second set, 32, 33, 34, 35, 36, 37, 38.

  The submagnets 21 to 24 and 31 to 38 are arranged such that two or more submagnets exist between two adjacent main magnets of the main magnets 11, 12, and 13. In the present embodiment, submagnets 31, 21, 32, 33, 22, and 34 are arranged in this order in the X direction between the main magnet 11 and the main magnet 12. Between the main magnet 12 and the main magnet 13, submagnets 35, 23, 36, 37, 24, and 38 are arranged in this order in the X direction.

  Each of the submagnets 21 to 24 and 31 to 38 is a position between two adjacent main magnets of the main magnets 11, 12, and 13, and the closer main magnet of the two main magnets. Are arranged at different positions in the first direction X1 by m × {1 / (2n−1)} × D. Hereinafter, this requirement is referred to as a first requirement. n is an integer of 2 or more, and varies depending on the set of submagnets. In the first set, n is 2, and in the second set, n is 3. m is an integer of 1 or more, and varies depending on the position of the sub magnet.

  The positional relationship between the first set of submagnets 21 to 24 and the main magnets 11, 12, and 13 is specifically as follows. For the secondary magnet 21, the above-mentioned closer main magnet is the main magnet 11. For the secondary magnets 22 and 23, the above-mentioned main magnet is the main magnet 12. For the sub-magnet 24, the above-mentioned main magnet is the main magnet 13. Any of the secondary magnets 21 to 24 is located at a position where n is 2 and m is 1 in the first requirement, that is, the above-mentioned closer main magnet is D / 3 in the X direction or the −X direction. Are placed in different positions only. Further, the distance between the submagnets 21 and 22 and the distance between the submagnets 23 and 24 in the first direction X1 are D / 3.

  The positional relationship between the second set of submagnets 31 to 38 and the main magnets 11, 12, and 13 is specifically as follows. For the sub-magnet 31, the closer main magnet is the main magnet 11. For the sub-magnets 34 and 35, the above-mentioned main magnet is the main magnet 12. For the submagnet 38, the above-mentioned main magnet is the main magnet 13. The submagnets 31, 34, 35, and 38 each have a position where n is 3 and m is 1 in the first requirement, that is, the near main magnet is the X direction or the -X direction. Are arranged at different positions by D / 5.

  In addition, for the secondary magnet 32, the above-mentioned main magnet is the main magnet 11. For the secondary magnets 33 and 36, the above-mentioned main magnet is the main magnet 12. For the secondary magnet 37, the above-mentioned near main magnet is the main magnet 13. The submagnets 32, 33, 36, and 37 all have a position where n is 3 and m is 2 in the first requirement, that is, the closer main magnet is the X direction or the -X direction. Are arranged at different positions by 2D / 5.

  Further, in the first direction X1, the interval between the submagnets 31, 32, the interval between the submagnets 32, 33, the interval between the submagnets 33, 34, the interval between the submagnets 35, 36, the interval between the submagnets 36, 37, and the submagnet. The distance between the magnets 37 and 38 is D / 5.

  Next, the magnetization directions of the plurality of main magnets and the plurality of submagnets will be described. The directions of magnetization of two main magnets adjacent to each other among the plurality of main magnets, that is, the main magnets 11, 12, 13 are opposite to each other. In FIG. 2, the arrows drawn on the main magnets 11, 12, and 13 indicate the magnetization directions of the main magnets 11, 12, and 13. In FIG. 2, the magnetization direction of the main magnets 11 and 13 is the Z direction, and the magnetization direction of the main magnet 12 is the −Z direction.

  Moreover, the arrow drawn on the submagnets 21-24 and 31-38 in FIG. 3 represents the direction of magnetization of the submagnets 21-24, 31-38. Of each set of submagnets, the direction of magnetization of the submagnet arranged at a position where m is 1 is the same as the direction of magnetization of the main magnet closest to the submagnet. Hereinafter, this requirement is referred to as a second requirement. This second requirement applies to all the submagnets 21 to 24 of the first set and some of the submagnets 31, 34, 35, and 38 of the second set. As shown in FIG. 2, the magnetization directions of the submagnets 21 and 31 are the same as the magnetization direction of the main magnet 11 (Z direction). The magnetization directions of the sub magnets 22, 23, 34, and 35 are the same as the magnetization direction of the main magnet 12 (−Z direction). The magnetization directions of the submagnets 24 and 38 are the same as the magnetization direction of the main magnet 13 (Z direction).

  Further, among the secondary magnets in each set, the direction of magnetization of the secondary magnet arranged at a position where m is 2 or more is opposite to the direction of magnetization of each of the two secondary magnets in the same set on both sides of the secondary magnet. It is. Hereinafter, this requirement is referred to as a third requirement. The third requirement applies to the other partial magnets 32, 33, 36, and 37 of the second set. As shown in FIG. 2, the direction of magnetization of the secondary magnet 32 is the direction opposite to the direction of magnetization of the secondary magnets 31 and 33 (−Z direction). The direction of magnetization of the submagnet 33 is the direction opposite to the direction of magnetization of the submagnets 32 and 34 (Z direction). The direction of magnetization of the submagnet 36 is the direction opposite to the direction of magnetization of the submagnets 35 and 37 (Z direction). The direction of magnetization of the submagnet 37 is the direction opposite to the direction of magnetization of the submagnets 36 and 38 (−Z direction).

  Hereinafter, first and second examples of the magnetic sensor 3 will be described. First, a first example of the magnetic sensor 3 will be described with reference to FIGS. 4 and 5. FIG. 4 is a perspective view showing a first example of the magnetic sensor 3. FIG. 5 is a circuit diagram showing a configuration of the first example of the magnetic sensor 3.

  As shown in FIGS. 4 and 5, in the first example, the magnetic sensor 3 includes a first detection unit 71, a second detection unit 72, a third detection unit 73, and a fourth detection. Part 74. Each of the first to fourth detection units 71 to 74 includes at least one magnetoresistance effect element. Each of the first to fourth detection units 71 to 74 may include a plurality of magnetoresistance effect elements connected in series. The first to fourth detection units 71 to 74 are arranged in this order in the Z direction. In FIG. 4, the first to fourth detection units 71 to 74 are drawn larger than the actual size for easy understanding. Further, the arrangement of the first to fourth detection units 71 to 74 is not limited to the example shown in FIG. For example, the first to fourth detection units 71 to 74 may be stacked in the Y direction.

  As shown in FIG. 5, in the first example, the magnetic sensor 3 further includes two power supply ports V11 and V12, two ground ports G11 and G12, and two output ports E11 and E12. Yes. The first detection unit 71 is provided between the power supply port V11 and the output port E11. The second detection unit 72 is provided between the power supply port V12 and the output port E12. The third detection unit 73 is provided between the output port E11 and the ground port G11. The fourth detection unit 74 is provided between the output port E12 and the ground port G12. A power supply voltage having a predetermined magnitude is applied to the power supply ports V11 and V12. The ground ports G11 and G12 are connected to the ground.

  The magnetoresistive effect element is, for example, a spin valve type magnetoresistive effect element. The spin-valve magnetoresistive element includes a magnetization fixed layer whose magnetization direction is fixed, a free layer that is a magnetic layer whose magnetization direction changes according to the direction DM of the applied magnetic field, a magnetization fixed layer, and a free layer. And a nonmagnetic layer disposed therebetween. The spin valve magnetoresistive element may be a TMR element or a GMR element. In the TMR element, the nonmagnetic layer is a tunnel barrier layer. In the GMR element, the nonmagnetic layer is a nonmagnetic conductive layer. In the spin-valve magnetoresistive effect element, the resistance value changes according to the angle formed by the magnetization direction of the free layer with respect to the magnetization direction of the magnetization fixed layer, and the resistance value is minimum when this angle is 0 °. When the angle is 180 °, the resistance value becomes the maximum value. In FIG. 4, the arrows drawn on the first to fourth detection units 71 to 74 represent the directions of magnetization of the magnetization fixed layers of the magnetoresistive effect elements included therein. In FIG. 5, solid arrows indicate the magnetization directions of the magnetization fixed layer of the magnetoresistive effect element, and white arrows indicate the magnetization directions of the free layer of the magnetoresistive effect element.

  The magnetization direction of the magnetization fixed layer of the magnetoresistive effect element included in the first detection unit 71 is the Z direction, and the magnetization direction of the magnetization fixed layer of the magnetoresistance effect element included in the third detection unit 73 is , -Z direction. In this case, the potential of the output port E11 changes according to the cosine of the applied magnetic field angle θM.

  The magnetization direction of the magnetization fixed layer of the magnetoresistive effect element included in the second detection unit 72 is the X direction, and the magnetization direction of the magnetization fixed layer of the magnetoresistive effect element included in the fourth detection unit 74 is , -X direction. In this case, the potential of the output port E12 changes according to the sine of the applied magnetic field angle θM.

  The magnetic sensor 3 further includes an angle calculation unit 75. The angle calculation unit 75 can be realized by, for example, an application specific integrated circuit (ASIC) or a microcomputer. The angle calculation unit 75 generates a detection value θs having a corresponding relationship with the applied magnetic field angle θM based on the potential of the output port E11 and the potential of the output port E12. Specifically, for example, the angle calculation unit calculates θs by the following equation (1). “Atan” represents an arc tangent.

  θs = atan (Sb / Sa) (1)

  In the expression (1), Sa is a signal normalized so that the maximum value and the minimum value of the potential of the output port E11 are 1 and −1, respectively. Sb is a signal normalized so that the maximum value and the minimum value of the potential of the output port E12 are 1 and −1, respectively. Sa and Sb are generated by the angle calculation unit 75.

  Within the range of θs between 0 ° and less than 360 °, the solution of θs in Equation (1) has two values that differ by 180 °. However, it is possible to determine which of the two solutions of θs in Equation (1) is the true value of θs by the positive / negative combination of Sa and Sb. The angle calculation unit obtains θs within a range of 0 ° or more and less than 360 ° based on the determination of Expression (1) and the positive / negative combination of Sa and Sb.

  Next, a second example of the magnetic sensor 3 will be described with reference to FIGS. FIG. 6 is a perspective view showing a second example of the magnetic scale 2 and the magnetic sensor 3. FIG. 7 is a circuit diagram showing a configuration of the second example of the magnetic sensor 3.

  As shown in FIGS. 6 and 7, in the second example, the magnetic sensor 3 includes a first detector 81 including a first Hall element H1 and a third Hall element H3, and a second Hall. A second detection unit 82 including the element H2 and the fourth Hall element H4, a substrate 83 made of a nonmagnetic material and having an upper surface 83a, and a yoke 84 made of a magnetic material are included. The upper surface 83a is parallel to the XZ plane. In FIG. 6, the substrate 83, the yoke 84, and the Hall elements H1 to H4 are drawn larger than the actual size for easy understanding.

  The first to fourth Hall elements H1 to H4 are embedded in the substrate 83 in such a posture that the magnetosensitive surface is parallel to the upper surface 83a in the vicinity of the upper surface 83a. The first and third Hall elements H1, H3 are arranged in the Z direction. The second and fourth Hall elements H2 and H4 are arranged in the X direction.

  The yoke 84 has a disk shape. The yoke 84 is disposed on the upper surface 83a of the substrate 83 so as to stride over each of the first to fourth Hall elements H1 to H4.

  As shown in FIG. 7, the first detection unit 81 further includes a power supply port V21, a ground port G21, two output ports E21 and E22, and a difference detector 85. The second detection unit 82 further includes a power port V22, a ground port G22, two output ports E23 and E24, and a difference detector 86. Each of the first to fourth Hall elements H1 to H4 has a power supply terminal Ha, a ground terminal Hc, and two output terminals Hb and Hd.

  In the first detection unit 81, the power supply terminals Ha of the first and third Hall elements H1, H3 are connected to the power supply port V21. The ground terminals Hc of the first and third Hall elements H1, H3 and the output terminals Hd of the first and third Hall elements H1, H3 are connected to the ground port G21. The output terminal Hb of the first Hall element H1 is connected to the output port E21. The output terminal Hb of the third Hall element H3 is connected to the output port E22. A power supply voltage having a predetermined magnitude is applied to the power supply port V21. The ground port G21 is connected to the ground.

  In the second detection unit 82, the power supply terminals Ha of the second and fourth Hall elements H2, H4 are connected to the power supply port V22. The ground terminals Hc of the second and fourth Hall elements H2, H4 and the output terminals Hd of the second and fourth Hall elements H2, H4 are connected to the ground port G22. The output terminal Hb of the second Hall element H2 is connected to the output port E23. The output terminal Hb of the fourth Hall element H4 is connected to the output port E24. A power supply voltage having a predetermined magnitude is applied to the power supply port V22. The ground port G22 is connected to the ground.

  The yoke 84 receives an applied magnetic field and generates an output magnetic field. The output magnetic field includes an output magnetic field component in a direction parallel to the Y direction, and changes in accordance with the applied magnetic field. Specifically, when the yoke 84 receives a component in the Z direction of the applied magnetic field, the yoke 84 generates an output magnetic field component in the Y direction in the vicinity of the first Hall element H1, and in the vicinity of the third Hall element H3. Generates an output magnetic field component in the -Y direction. When the yoke 84 receives a component of the applied magnetic field in the −Z direction, the direction of the output magnetic field component is opposite to that when the yoke 84 receives the component of the applied magnetic field in the Z direction.

  The first and third Hall elements H1 and H3 detect the output magnetic field component in the Y direction or −Y direction generated in the vicinity of the first and third Hall elements H1 and H3, and thereby the Z direction of the applied magnetic field. Alternatively, a component in the −Z direction is detected. The potential difference between the output ports E21 and E22 varies depending on the component in the Z direction or −Z direction of the applied magnetic field. The difference detector 85 outputs a signal corresponding to the potential difference between the output ports E21 and E22 as the first detection signal S1.

  Further, when the yoke 84 receives a component in the X direction of the applied magnetic field, the yoke 84 generates an output magnetic field component in the Y direction in the vicinity of the second Hall element H2, and −Y in the vicinity of the fourth Hall element H4. Generates an output magnetic field component in the direction. When the yoke 84 receives the component of the applied magnetic field in the −X direction, the direction of the output magnetic field component is opposite to that when the yoke 84 receives the component of the applied magnetic field in the X direction.

  The second and fourth Hall elements H2 and H4 detect the output magnetic field component in the Y direction or −Y direction generated in the vicinity of the second and fourth Hall elements H2 and H4, and thereby the X direction of the applied magnetic field. Alternatively, a component in the −X direction is detected. The potential difference between the output ports E23 and E24 changes according to the component of the applied magnetic field in the X direction or -X direction. The difference detector 86 outputs a signal corresponding to the potential difference between the output ports E23 and E24 as the second detection signal S2.

  As shown in FIG. 7, in the second example, the magnetic sensor 3 further includes an angle calculation unit 87. The angle calculation unit 87 can be realized by, for example, an ASIC or a microcomputer. The angle calculator 87 generates a detection value θs that has a corresponding relationship with the applied magnetic field angle θM, based on the first and second detection signals S1 and S2. Specifically, for example, the angle calculation unit 87 calculates θs by the following equation (2).

  θs = atan (S2 / S1) (2)

  When θs is in the range of 0 ° to less than 360 °, the solution of θs in Equation (2) has two values that differ by 180 °. However, it is possible to determine which of the two solutions of θs in Equation (2) is the true value of θs by the positive / negative combination of S1 and S2. The angle calculation unit 87 obtains θs within the range of 0 ° or more and less than 360 ° by determining the combination of the expression (2) and the positive / negative combination of S1 and S2.

  Next, the operation and effect of the magnetic sensor system 1 according to the present embodiment will be described. In the present embodiment, main magnets 11 to 13 generate a main magnetic field. When the external magnetic field is composed only of the main magnetic field, the curve representing the change in the intensity of the unidirectional component of the applied magnetic field with respect to the change in the relative position P2 is an ideal component that draws a sine curve and (2n-1) And at least one harmonic component corresponding to the next harmonic. Note that n is the same as n in the first requirement described above, and is an integer of 2 or more.

  Hereinafter, a curve representing a change in intensity of a component in one direction of the applied magnetic field with respect to a change in the relative position P2 is referred to as an applied magnetic field characteristic curve. In addition, the component in the first direction X1 of the applied magnetic field is referred to as a first component, and the component in the direction parallel to the Z direction (second direction) of the applied magnetic field is referred to as a second component.

  Both the curve representing the change in the intensity of the first component of the applied magnetic field with respect to the change in the relative position P2 and the curve representing the change in the intensity of the second component of the applied magnetic field with respect to the change in the relative position P2 are both applied magnetic fields. Corresponds to the characteristic curve. When the external magnetic field is composed only of the main magnetic field, the curve indicating the change in the intensity of the first component of the applied magnetic field with respect to the change in the relative position P2 and the intensity of the second component of the applied magnetic field with respect to the change in the relative position P2. Each of the curves representing the change includes an ideal component and at least one harmonic component.

  FIG. 8 is a characteristic diagram showing a main magnetic flux density that is a magnetic flux density corresponding to the main magnetic field at the reference position PR. The main magnetic flux density is a general term for the magnetic flux density Bmx and the magnetic flux density Bmx. The magnetic flux density Bmx is a magnetic flux density corresponding to the first component of the applied magnetic field when the external magnetic field consists only of the main magnetic field. The magnetic flux density Bmz is a magnetic flux density corresponding to the second component of the applied magnetic field when the external magnetic field consists only of the main magnetic field. FIG. 8 shows Bmx and Bmz.

Note that FIG. 8 is obtained by simulation by setting the distance between the protection unit 62 of the magnetic scale 2 and the magnetic sensor 3 to 2.5 mm and the total volume of the plurality of main magnets and the plurality of submagnets to 600 mm ^3. . In FIG. 8, the horizontal axis represents the relative position P2, and the vertical axis represents the values of the magnetic flux densities Bmx and Bmz. The unit of the horizontal axis is -1 when the positions of the main magnet 13 and the reference position PR in the first direction X1 coincide with each other, and the first direction X1 of each of the main magnet 11 and the reference position PR. Is an arbitrary unit with a value of 1 when the positions coincide. The vertical axis represents the magnetic flux density corresponding to the magnetic field in the X direction or the Z direction as a positive value, and represents the magnetic flux density corresponding to the magnetic field in the −X direction or the −Z direction as a negative value.

  As shown in FIG. 8, the curves representing changes in the magnetic flux densities Bmx and Bmz with respect to the change in the relative position P2 are both an ideal component that draws a sine curve and the (2n−1) -order harmonics of this ideal component. And at least one harmonic component corresponding to. Both of the curves representing changes in the magnetic flux densities Bmx and Bmz with respect to the change in the relative position P2 correspond to the applied magnetic field characteristic curve when the external magnetic field is composed only of the main magnetic field.

  As described above, the angle formed by the direction DM of the applied magnetic field with respect to the reference direction DR, that is, the applied magnetic field angle θM changes as the relative position P2 changes. An ideal change in the applied magnetic field angle θM with respect to the change in the relative position P2 is represented by a straight line. Hereinafter, this straight line is referred to as an ideal straight line. When the external magnetic field is composed only of the main magnetic field, as described above, since the curves representing the changes in the magnetic flux densities Bmx and Bmx with respect to the change in the relative position P2 both include at least one harmonic component, A characteristic curve representing a change in applied magnetic field angle θM with respect to a change in position P2 (hereinafter referred to as an angle characteristic curve) deviates from an ideal straight line. As a result, an error occurs in the detected value θs generated by the magnetic sensor 3. Hereinafter, the error of the detected value θs is referred to as an angle error.

  On the other hand, in this Embodiment, the magnetic scale 2 contains the submagnets 21-24 and 31-38 which generate | occur | produce a submagnetic field in addition to the main magnets 11,12,13. When the ideal change in the applied magnetic field information with respect to the change in the relative position P2 is regarded as an ideal characteristic, the sub magnetic field changes the change in the applied magnetic field information with respect to the change in the relative position P2 as compared with the case where the external magnetic field is composed only of the main magnetic field. The main magnetic field is corrected so that the characteristic to be expressed approaches the ideal characteristic.

  Particularly in the present embodiment, the change in the applied magnetic field information with respect to the change in the relative position P2 is the change in the applied magnetic field angle θM with respect to the change in the relative position P2. The ideal characteristic is an ideal change of the applied magnetic field angle θM with respect to the change of the relative position P2, and is represented by the ideal straight line. Further, the characteristic representing the change in the applied magnetic field angle θM with respect to the change in the relative position P2 is represented by an angle characteristic curve. The sub-magnetic field corrects the main magnetic field so that the maximum deviation of the angle characteristic curve from the ideal straight line is small.

  Further, in the present embodiment, in particular, each set of sub-magnets is for correcting the main magnetic field so that one harmonic component in the applied magnetic field characteristic curve is reduced. The first set of secondary magnets 21 to 24 reduces a harmonic component (hereinafter referred to as a third harmonic component) corresponding to the third harmonic in the applied magnetic field characteristic curve. The second set of submagnets 31 to 38 reduces a harmonic component (hereinafter referred to as a fifth harmonic component) corresponding to the fifth harmonic in the applied magnetic field characteristic curve. Hereinafter, the magnetic field generated by the first set of submagnets 21 to 24 is referred to as a first submagnetic field component, and the magnetic field generated by the second set of submagnets 31 to 38 is referred to as a second submagnetic field component. The sub magnetic field is a combination of the first sub magnetic field component and the second sub magnetic field component. The above first to third requirements are that the submagnets 21 to 24 are configured so that the third harmonic component is reduced by the first submagnetic field component and the fifth harmonic component is reduced by the second submagnetic field component. , 31 to 38 and requirements for defining the magnetization direction.

  Hereinafter, it will be described with reference to FIGS. 8 to 11 that the third harmonic component and the fifth harmonic component are reduced by the first and second sub-magnetic field components.

  FIG. 9 is a characteristic diagram showing a first sub-magnetic flux density that is a magnetic flux density corresponding to the first sub-magnetic field component at the reference position PR. FIG. 10 is a characteristic diagram showing a second sub-magnetic flux density that is a magnetic flux density corresponding to the second sub-magnetic field component at the reference position PR. FIG. 11 is a characteristic diagram showing an applied magnetic flux density that is a magnetic flux density corresponding to the applied magnetic field. 9 to 11 are obtained by simulation. The simulation conditions in FIGS. 9 to 11 are the same as the simulation conditions in FIG.

  The first sub magnetic flux density is a general term for the magnetic flux density Bsx1 and the magnetic flux density Bsz1. The magnetic flux density Bsx1 is a magnetic flux density corresponding to the first component of the applied magnetic field when the external magnetic field is composed of only the first sub-magnetic field component. The magnetic flux density Bsz1 is a magnetic flux density corresponding to the second component of the applied magnetic field when the external magnetic field is composed of only the first sub-magnetic field component. FIG. 9 shows Bs1x and Bs1z. In FIG. 9, the horizontal axis represents the relative position P2, and the vertical axis represents the values of the magnetic flux densities Bs1x and Bs1z. The positive and negative meanings of the vertical axis are the same as those in FIG.

  The second sub magnetic flux density is a generic name of the magnetic flux density Bsx2 and the magnetic flux density Bsz2. The magnetic flux density Bsx2 is a magnetic flux density corresponding to the first component of the applied magnetic field when the external magnetic field is composed of only the second sub-magnetic field component. The magnetic flux density Bsz2 is a magnetic flux density corresponding to the second component of the applied magnetic field when the external magnetic field is composed of only the second sub-magnetic field component. FIG. 10 shows Bs2x and Bs2z. In FIG. 10, the horizontal axis represents the relative position P2, and the vertical axis represents the values of the magnetic flux densities Bs2x and Bs2z. The positive and negative meanings of the vertical axis are the same as those in FIG.

  The applied magnetic flux density is a general term for the magnetic flux density Bx and the magnetic flux density Bz. The magnetic flux density Bs is a magnetic flux density corresponding to the first component of the applied magnetic field. The magnetic flux density Bsz2 is a magnetic flux density corresponding to the second component of the applied magnetic field. FIG. 11 shows Bx and Bz. In FIG. 11, the horizontal axis represents the relative position P2, and the vertical axis represents the values of the magnetic flux densities Bx and Bz. The positive and negative meanings of the vertical axis are the same as those in FIG. The magnetic flux density Bx is a combination of magnetic flux densities Bmx, Bs1x, and Bs2x. The magnetic flux density Bz is a combination of the magnetic flux densities Bmz, Bs1z, and Bs2z.

  As shown in FIG. 11, the curves representing changes in the magnetic flux densities Bx and Bz with respect to changes in the relative position P2 are curves representing changes in the magnetic flux densities Bmx and Bmz with respect to changes in the relative position P2 shown in FIG. Compared to, the curve is closer to a sine curve. This is because the third harmonic component and the fifth harmonic component of the magnetic flux density Bx are reduced by the action of the magnetic flux densities s1x and Bs2x and the magnetic flux density Bmz by the action of the magnetic flux densities Bs1z and Bs2z. 3 represents that the third harmonic component and the fifth harmonic component of the magnetic flux density Bz are reduced. From this, it can be seen that according to the present embodiment, the third and fifth harmonic components are reduced by the first and second sub-magnetic field components.

  In the present embodiment, the third and fifth harmonic components are reduced by the first and second sub-magnetic field components, so that the angular characteristics are compared with the case where the external magnetic field is composed only of the main magnetic field. The maximum deviation of the curve from the ideal straight line becomes smaller.

  Next, an angle characteristic curve in the example of the present embodiment (hereinafter referred to as the first example) will be specifically described in comparison with the magnetic sensor system of the first comparative example. The magnetic sensor system 1 according to the first embodiment is the magnetic sensor system 1 defined by the simulation conditions in FIGS. The magnetic sensor system of the first comparative example includes the magnetic scale 202 of the first comparative example in which all the submagnets are removed from the magnetic scale 2 in the first embodiment. FIG. 12 shows a magnetic scale 202 of the first comparative example. The arrangement and magnetization directions of the main magnets 11 to 13 in the magnetic scale 202 of the first comparative example are the same as those of the magnetic scale 2 in the first embodiment. Other configurations of the magnetic sensor system of the first comparative example are the same as those of the magnetic sensor system 1 of the first embodiment.

Next, an applied magnetic field based on an external magnetic field generated by the magnetic scale 202 of the first comparative example (hereinafter referred to as an applied magnetic field of the first comparative example) will be described. FIG. 13 is a characteristic diagram showing the applied magnetic flux density of the first comparative example, which is the magnetic flux density corresponding to the applied magnetic field of the first comparative example. The applied magnetic flux density of the first comparative example is a general term for the magnetic flux density Bcx and the magnetic flux density Bcz. The magnetic flux density Bcx is a magnetic flux density corresponding to the component in the first direction of the applied magnetic field of the first comparative example. The magnetic flux density Bcz is a magnetic flux density corresponding to a component in a direction parallel to the second direction of the applied magnetic field of the first comparative example. FIG. 13 shows Bcx and Bcz. In FIG. 13, the horizontal axis represents the relative position P2, and the vertical axis represents the values of the magnetic flux densities Bcx and Bcz. The positive and negative meanings of the vertical axis are the same as those in FIG. FIG. 13 is obtained by simulation by setting the distance between the protection unit 62 of the magnetic scale 202 and the magnetic sensor 3 to 2.5 mm and the total volume of the main magnets 11 to 13 to 600 mm ³ .

  The applied magnetic field of the first comparative example corresponds to the applied magnetic field when the external magnetic field consists only of the main magnetic field. The magnetic flux density Bcx corresponds to the first component of the applied magnetic field when the external magnetic field consists only of the main magnetic field. The magnetic flux density Bcz corresponds to the second component of the applied magnetic field when the external magnetic field consists only of the main magnetic field. Each of the curves representing changes in the magnetic flux densities Bcx and Bcz with respect to the change in the relative position P2 is an ideal component that draws a sine curve, and at least one harmonic corresponding to the (2n-1) th order harmonic of the ideal component. Contains ingredients. Both of the curves representing changes in the magnetic flux densities Bcx and Bcz with respect to the change in the relative position P2 correspond to the applied magnetic field characteristic curve when the external magnetic field is composed only of the main magnetic field.

  Next, the angle characteristic curve of the first comparative example will be described. Here, instead of the angle characteristic curve, a description will be given using a characteristic curve representing a change in the detected value θs with respect to a change in the relative position P2 (hereinafter referred to as a detected value characteristic curve). FIG. 14 is a characteristic diagram showing a detection value characteristic curve of the first comparative example. The detected value θs shown in FIG. 14 is obtained by simulation based on the applied magnetic field of the first comparative example. The simulation conditions in FIG. 14 are the same as the simulation conditions in FIG. In FIG. 14, the horizontal axis represents the relative position P2, and the vertical axis represents the detected value θs. In FIG. 14, a straight line denoted by reference numeral 91 represents a straight line representing an ideal change in the detected value θs with respect to a change in the relative position P2, and a curve denoted by reference numeral 92 represents a detected value characteristic curve. Hereinafter, the value of the detected value θs on the straight line representing the ideal change of the detected value θs with respect to the change of the relative position P2 is referred to as an ideal value of the detected value. In FIG. 14, the ideal value of the detected value when the positions of the main magnet 13 and the reference position PR in the first direction X1 coincide with each other is 0 °, and the first values of the main magnet 11 and the reference position PR are the first values. The ideal value of the detected value when the positions in the direction X1 coincide is 360 °.

  As shown in FIG. 14, the detected value characteristic curve (reference numeral 92) is deviated from the straight line denoted by reference numeral 91. The detected value is substantially the same as the angle characteristic curve, and the straight line denoted by reference numeral 91 is substantially the same as the ideal straight line. Therefore, in the first comparative example, it can be said that the angle characteristic curve deviates from the ideal straight line.

  Next, the angle error of the first comparative example will be described. FIG. 15 is a characteristic diagram showing the angle error of the first comparative example. The angle error shown in FIG. 15 is calculated based on the detected value θs and the ideal value of the detected value shown in FIG. In FIG. 15, the value obtained by subtracting the value obtained by subtracting the ideal value of the detected value at the relative position P2 from the detected value θs at the arbitrary relative position P2 by 360 ° is expressed as a percentage. It was an error. In FIG. 15, the horizontal axis represents the relative position P2, and the vertical axis represents the angle error.

  14 and 15 show a movable range ST in the magnetic sensor system of the first comparative example. The movable range ST shown in FIGS. 14 and 15 is matched to the movable range in the magnetic sensor system 1 of the first embodiment. The movable range in the magnetic sensor system 1 of the first embodiment will be described later. The angle error shown in FIG. 15 is calculated based on the detected value θs in the movable range ST shown in FIG. 14 and the ideal value of the detected value.

  Next, the angle characteristic curve in the first embodiment will be described. Here, the detection value characteristic curve is used instead of the angle characteristic curve. FIG. 16 is a characteristic diagram showing a detected value characteristic curve in the first embodiment. The detected value θs shown in FIG. 16 is obtained by simulation based on the applied magnetic field in the first embodiment. In FIG. 16, the horizontal axis represents the relative position P2, and the vertical axis represents the detected value θs. In FIG. 16, a straight line denoted by reference numeral 93 represents a straight line representing an ideal change in the detected value θs with respect to a change in relative position, and a curve denoted by reference numeral 94 represents a detected value characteristic curve. In FIG. 16, the ideal value of the detected value when the positions of the main magnet 13 and the reference position PR in the first direction X1 coincide with each other is set to 0 °, and the first values of the main magnet 11 and the reference position PR are the first. The ideal value of the detected value when the positions in the direction X1 coincide is 360 °.

  16 and 17 show the movable range ST in the magnetic sensor system 1 of the first embodiment. The movable range ST in FIG. 16 is a range in which the detected value θs is 0 ° to 360 °. The angle error shown in FIG. 17 is calculated based on the detected value θs in the movable range ST shown in FIG. 16 and the ideal value of the detected value.

  As shown in FIG. 16, the maximum deviation of the detected value characteristic curve (reference numeral 94) in the first embodiment from the straight line denoted by reference numeral 93 is the detected value characteristic in the first comparative example shown in FIG. The curve (symbol 92) is smaller than the maximum deviation from the straight line denoted by reference numeral 91. As described above, the detected value characteristic curve is substantially the same as the angle characteristic curve, and the straight line denoted by reference numeral 93 is substantially the same as the ideal straight line. Accordingly, the results shown in FIGS. 14 and 16 show that the maximum deviation of the angular characteristic curve in the first example from the ideal straight line is larger than the maximum deviation of the angular characteristic curve in the first comparative example from the ideal straight line. Is also small.

  Next, the angle error in the first embodiment will be described. FIG. 17 is a characteristic diagram showing angular errors in the first embodiment. The angle error shown in FIG. 17 is calculated based on the detected value θs and the ideal value of the detected value shown in FIG. The calculation method of the angle error is the same as the calculation method of the angle error shown in FIG. The angle error shown in FIG. 17 is a percentage obtained by dividing the value obtained by subtracting the ideal value of the detected value at the relative position P2 from the detected value θs at the arbitrary relative position P2 by 360 °. It is a thing. In FIG. 17, the horizontal axis represents the relative position P2, and the vertical axis represents the angle error. As shown in FIGS. 15 and 17, according to the first embodiment, the maximum value of the angle error can be reduced as compared with the first comparative example. The maximum value of the angle error corresponds to the maximum deviation of the angle characteristic curve from the ideal straight line.

  As described above, according to the magnetic sensor system 1 according to the present embodiment and the magnetic scale 2 used therefor, the angle characteristic curve has a maximum from the ideal straight line as compared with the case where the external magnetic field is composed only of the main magnetic field. The deviation can be reduced, and as a result, high detection accuracy can be realized in the magnetic sensor system 1.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 18 is a perspective view showing the magnetic scale 2 according to the present embodiment. The configuration of the magnetic scale 2 according to the present embodiment is the same as that of the first embodiment except that the second set of submagnets 31 to 38 in the first embodiment is not provided. . The arrangement and magnetization directions of the main magnets 11 to 13 and the first set of submagnets 21 to 24 in the present embodiment are the same as those in the first embodiment. The external magnetic field in the present embodiment is a combination of the main magnetic field generated by the main magnets 11 to 13 and the first sub magnetic field component generated by the first set of sub magnets 21 to 24.

  As described in the first embodiment, the first set of submagnets 21 to 24 is for correcting the main magnetic field so that the third harmonic component is reduced. In the present embodiment, the third-order harmonic component is reduced, so that the maximum deviation of the angle characteristic curve from the ideal straight line can be reduced as compared with the case where the external magnetic field is composed only of the main magnetic field.

  In the present embodiment, the effects based on the second set of submagnets 31 to 38 described in the first embodiment cannot be obtained. Other configurations, operations, and effects in the present embodiment are the same as those in the first embodiment.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 19 is a perspective view showing the magnetic scale 2 according to the present embodiment. In addition to the four submagnets 21 to 24 constituting the first set and the eight submagnets 31 to 38 constituting the second set, the magnetic scale 2 according to the present embodiment is a plurality of submagnets. , 12 sub-magnets 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52 constituting the third set are included. Other configurations of the magnetic scale 2 according to the present embodiment are the same as those of the first embodiment.

  The arrangement and magnetization directions of the main magnets 11 to 13 and the sub magnets 21 to 24 and 31 to 38 are the same as those in the first embodiment. Hereinafter, the arrangement of the submagnets 41 to 52 and the direction of magnetization will be described with reference to FIG. First, the arrangement of the submagnets 41 to 52 will be described. In the present embodiment, submagnets 41, 31, 42, 21, 32, 43, 44, 33, 22, 45, 34, and 46 are arranged in this order in the X direction between the main magnet 11 and the main magnet 12. Has been placed. Between the main magnet 12 and the main magnet 13, submagnets 47, 35, 48, 23, 36, 49, 50, 37, 24, 51, 38, 52 are arranged in this order in the X direction.

  Each of the submagnets 41 to 52 satisfies the first requirement regarding the arrangement of the submagnets described in the first embodiment, similarly to the submagnets 21 to 24 and 31 to 38. That is, each of the submagnets 41 to 52 is a position between two adjacent main magnets of the main magnets 11, 12, and 13, and is the closest main magnet of the two main magnets. In the first direction X1, they are arranged at different positions by m × {1 / (2n−1)} × D. D, m, and n are as described in the first embodiment. In the third set, n is 4.

  The positional relationship between the third set of submagnets 41 to 52 and the main magnets 11, 12, and 13 is specifically as follows. For the sub-magnet 41, the closer main magnet is the main magnet 11. For the secondary magnets 46 and 47, the above-mentioned main magnet is the main magnet 12. For the sub-magnet 52, the above-mentioned near main magnet is the main magnet 13. The submagnets 41, 46, 47, 52 are all in the X direction or −X with respect to the position where n is 4 and m is 1 in the first requirement. It is arranged at a position different by D / 7 in the direction.

  In addition, for the secondary magnet 42, the closer main magnet is the main magnet 11. For the submagnets 45 and 48, the above-mentioned main magnet is the main magnet 12. For the sub-magnet 51, the closer main magnet is the main magnet 13. The submagnets 42, 45, 48 and 51 all have a position where n is 4 and m is 2 in the first requirement, that is, the closer main magnet is in the X direction or -X. They are arranged at different positions in the direction by 2D / 7.

  In addition, for the secondary magnet 43, the above-mentioned closer main magnet is the main magnet 11. For the submagnets 445 and 49, the above-mentioned main magnet is the main magnet 12. For the secondary magnet 50, the above-mentioned main magnet is the main magnet 13. The submagnets 43, 44, 49, and 50 are all located at a position where n is 4 and m is 3 in the first requirement, that is, the above-mentioned closer main magnet is in the X direction or the −X direction. Are arranged at different positions by 3D / 7.

  Further, in the first direction X1, the interval between the submagnets 41, 42, the interval between the submagnets 42, 43, the interval between the submagnets 43, 44, the interval between the submagnets 44, 45, the interval between the submagnets 45, 46, The interval between the magnets 47 and 48, the interval between the submagnets 48 and 49, the interval between the submagnets 49 and 50, the interval between the submagnets 50 and 51, and the interval between the submagnets 51 and 52 are D / 7.

  Next, the magnetization direction of the submagnets 41 to 52 will be described. Each of the submagnets 41 to 52 satisfies the second or third requirement related to the direction of magnetization of the submagnet described in the first embodiment, similarly to the submagnets 21 to 24 and 31 to 38. The second requirement is that the magnetization direction of the secondary magnet arranged at the position where m is 1 among the secondary magnets in each set is the same as the magnetization direction of the primary magnet closest to the secondary magnet. Is. The second requirement applies to the submagnets 41, 46, 47, and 52 of the third set. The magnetization direction of the submagnet 41 is the same direction (Z direction) as the magnetization direction of the main magnet 11. The magnetization directions of the submagnets 46 and 47 are the same as the magnetization direction of the main magnet 12 (−Z direction). The magnetization direction of the submagnet 52 is the same direction (Z direction) as the magnetization direction of the main magnet 13.

  The third requirement is that the direction of magnetization of the secondary magnets arranged at positions where m is 2 or more among the secondary magnets of each set is the same as that of the two secondary magnets of the same set on both sides of the secondary magnet. This is opposite to the direction of magnetization. The third requirement applies to the submagnets 42 to 45 and 48 to 51 other than the submagnets 41, 46, 47, and 52 in the third set. The magnetization direction of the submagnet 42 is the opposite direction (−Z direction) to the magnetization direction of the submagnets 41 and 43. The direction of magnetization of the submagnet 43 is the direction opposite to the direction of magnetization of the submagnets 42 and 44 (Z direction). The direction of magnetization of the submagnet 44 is the direction opposite to the direction of magnetization of the submagnets 43 and 45 (−Z direction). The direction of magnetization of the submagnet 45 is the direction opposite to the direction of magnetization of the submagnets 44 and 46 (Z direction). The magnetization direction of the secondary magnet 48 is the direction opposite to the magnetization direction of the secondary magnets 47 and 49 (Z direction). The magnetization direction of the submagnet 49 is opposite to the magnetization direction of the submagnets 48 and 50 (−Z direction). The magnetization direction of the secondary magnet 50 is the direction opposite to the magnetization direction of the secondary magnets 49 and 51 (Z direction). The direction of magnetization of the submagnet 51 is the direction opposite to the direction of magnetization of the submagnets 50 and 52 (−Z direction).

  In the present embodiment, the third set of sub-magnets 41 to 52 includes a harmonic component (hereinafter referred to as 7) corresponding to the seventh harmonic of the ideal component in the applied magnetic field characteristic curve described in the first embodiment. Called the second harmonic component). Hereinafter, the magnetic field generated by the third set of submagnets 41 to 52 is referred to as a third submagnetic field component. The sub magnetic field in the present embodiment includes a first sub magnetic field component generated by the first set of sub magnets 21 to 24, and a second sub magnetic field component generated by the second set of sub magnets 31 to 38. , And the third sub-magnetic field component are combined. Further, the first to third requirements in the present embodiment are that the third harmonic component is reduced by the first sub-magnetic field component, the fifth harmonic component is reduced by the second sub-magnetic field component, and the third This is a requirement for defining the positions and the magnetization directions of the submagnets 21 to 24, 31 to 38, and 41 to 52 so that the seventh harmonic component is reduced by the submagnetic field component. In the present embodiment, when the third to fifth harmonic components and the seventh harmonic component are reduced by the first to third sub magnetic field components, the external magnetic field is composed only of the main magnetic field. As a result, the maximum deviation of the angle characteristic curve from the ideal straight line can be reduced, and as a result, higher detection accuracy can be realized in the magnetic sensor system 1.

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

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 20 is a perspective view showing the magnetic sensor system 1 according to the present embodiment. FIG. 21 is an explanatory diagram for explaining the arrangement and magnetization directions of the main magnet and the sub-magnet in the present embodiment.

  The magnetic sensor system 1 according to the present embodiment includes a magnetic scale 102 that generates an external magnetic field, instead of the magnetic scale 2 in the first embodiment. The magnetic scale 102 includes a plurality of main magnets that generate a main magnetic field, a plurality of submagnets that generate a submagnetic field, and a substrate 161 that supports the plurality of main magnets and the plurality of submagnets. In the present embodiment, the substrate 161 has a ring shape.

  The substrate 161 has an upper surface 161a and a lower surface 161b. The plurality of main magnets and the plurality of submagnets are disposed on the upper surface 161 a of the substrate 161. The magnetic sensor 3 is disposed so as to face the upper surface 161 a of the substrate 161.

  The magnetic scale 102 rotates in a rotation direction R about a predetermined center axis C in conjunction with a movable object (not shown) that rotates. Thereby, the relative position of the magnetic scale 102 with respect to the magnetic sensor 3 changes within a predetermined range along the rotation direction R. The rotation direction R includes the clockwise direction in FIG. 21 and the counterclockwise direction in FIG. The rotation direction R corresponds to the first direction in the present invention.

  The plurality of main magnets are arranged at intervals along the rotation direction R (first direction). The plurality of sub-magnets are arranged at positions different from the plurality of main magnets along the rotation direction R (first direction). Each of the plurality of main magnets and the plurality of submagnets has a first end face closest to the central axis C and a second end face farthest from the central axis C. The distances from the central axis C to the first end faces of the plurality of main magnets are the same value CR1, and the distances from the central axis C to the second end faces of the plurality of main magnets are the same value CR2.

  Here, the definition of the position in the rotation direction R of each of the plurality of main magnets and the plurality of submagnets will be described. First, the position reference circle is defined as follows. The position reference circle is a circle located on the upper surface 161a of the substrate 161, the center of which is located on the central axis C, and the radius is the average value of CR1 and CR2. In the position reference circle, the position of the midpoint of the line segment that overlaps each of the plurality of main magnets and the plurality of submagnets is set as the position in the rotation direction R of each of the plurality of main magnets and the plurality of submagnets. The interval between any two of the plurality of main magnets and the plurality of sub-magnets is represented by the length of an arc connecting the positions of the two magnets along the position reference circle.

  In the present embodiment, the magnetic sensor 3 is located away from the magnetic scale 102 in the direction parallel to the central axis C. The direction parallel to the central axis C corresponds to the second direction in the present invention.

  In the present embodiment, as shown in FIGS. 20 and 21, the X direction, the Y direction, and the Z direction are defined. In this embodiment, a direction parallel to the central axis C and extending from the lower surface 161b of the substrate 161 toward the upper surface 161a is defined as a Z direction, and a direction opposite to the Z direction is defined as a -Z direction. In FIG. 21, the Z direction is a direction from the back toward the front. The relationship between the X direction, the Y direction, and the Z direction and the direction related to the magnetic sensor 3 such as the reference direction is the same as that in the first embodiment.

  Next, with reference to FIG. 21, the arrangement of the plurality of main magnets and the plurality of submagnets and the direction of magnetization will be described. First, the arrangement of a plurality of main magnets and a plurality of submagnets will be described. In the present embodiment, the magnetic scale 102 includes two main magnets 111 and 112 as a plurality of main magnets. The main magnets 111 and 112 are arranged at an interval D along the rotation direction R (first direction). Particularly in the present embodiment, the interval D is equal to ½ of the circumference of the position reference circle.

  In the present embodiment, the magnetic scale 102 includes, as a plurality of submagnets, four submagnets 121, 122, 123, and 124 that form the first set, and eight submagnets that form the second set. 131, 132, 133, 134, 135, 136, 137, and 138.

  Here, the first region and the second region are defined as follows. The first region is a region on the upper surface 161 a of the substrate 161, and is a region that proceeds from the main magnet 111 in the counterclockwise direction in FIG. 21 to the main magnet 112. The second region is a region on the upper surface 161a of the substrate 161, and is a region from the main magnet 112 to the main magnet 111 in the counterclockwise direction in FIG. The first region and the second region both correspond to “between two adjacent main magnets among the plurality of main magnets” in the present invention.

  In the first region, the secondary magnets 131, 121, 132, 133, 122, and 134 are arranged in this order from the vicinity of the main magnet 111 in the counterclockwise direction in FIG. In the second region, the secondary magnets 135, 123, 136, 137, 124, and 138 are arranged in this order from the vicinity of the main magnet 112 in the counterclockwise direction in FIG.

  The magnetic scale 102 is a scale in which the magnetic scale 2 (see FIG. 1) according to the first embodiment, which is a linear scale, is deformed into a ring shape so that the position of the main magnet 11 and the position of the main magnet 13 coincide. It corresponds to. The main magnet 111 corresponds to the main magnet 11 and the main magnet 13 in the first embodiment. The main magnet 112 corresponds to the main magnet 12 in the first embodiment.

  The first region corresponds to between the main magnet 11 and the main magnet 12 in the first embodiment. The submagnets 131, 121, 132, 133, 122, and 134 arranged in the first area correspond to the submagnets 31, 21, 32, 33, 22, and 34 in the first embodiment, respectively. The positional relationship between the main magnets 111 and 112 and the submagnets 131, 121, 132, 133, 122, and 134 is basically the main magnets 11 and 12 and the submagnets 31, 21, and 32 in the first embodiment. , 33, 22 and 34 are the same as the positional relationship.

  The second region corresponds to between the main magnet 12 and the main magnet 13 in the first embodiment. The submagnets 135, 123, 136, 137, 124, and 138 arranged in the second region correspond to the submagnets 35, 23, 36, 37, 24, and 38 in the first embodiment, respectively. The positional relationship between the main magnets 112 and 111 and the submagnets 135, 123, 136, 137, 124, and 138 is basically the main magnets 12 and 13 and the submagnets 35, 23, and 36 in the first embodiment. , 37, 24, 38.

  Hereinafter, the arrangement of the sub magnets 121 to 124 and 131 to 138 will be specifically described. Each of the submagnets 121 to 124 and 131 to 138 is the same as the submagnets 21 to 24 and 31 to 38 in the first embodiment, and is the first related to the arrangement of the submagnets described in the first embodiment. Meet the requirements. That is, each of the submagnets 121 to 124 and 131 to 138 has a rotation direction R (first direction) in the first region or the second region, which is closer to the main magnet 111 or 112. ) Are arranged at different positions by m × {1 / (2n−1)} × D. m and n are as described in the first embodiment. In the first set, n is 2, and in the second set, n is 3.

  The positional relationship between the first set of submagnets 121 to 124 and the main magnets 111 and 112 is that the main magnets 111 and 112 are arranged along the rotation direction R (first direction) and the main magnet closer to the submagnet 124. Except for the point that the magnet becomes the main magnet 111, the positional relationship between the submagnets 21 to 24 and the main magnets 11 to 13 described in the first embodiment is the same. That is, each of the submagnets 121 to 124 is the position where n is 2 and m is 1 in the first requirement, that is, the closer main magnet 111, 112 is the main magnet of FIG. Are arranged at different positions by D / 3 in the clockwise or counterclockwise direction.

  Further, in the rotation direction R (first direction), the distance between the submagnets 121 and 122 and the distance between the submagnets 123 and 124 are each D / 3.

  The positional relationship between the second set of submagnets 131 to 138 and the main magnets 111 and 112 is that they are arranged along the rotation direction R (first direction) and closer to the submagnets 137 and 138. The main magnet 111 is the same as the positional relationship between the sub-magnets 31 to 38 and the main magnets 11 to 13 described in the first embodiment except that the main magnet 111 becomes the main magnet 111. That is, the submagnets 131, 134, 135, and 138 are all located at positions where n is 3 and m is 1 in the first requirement, that is, the closer main magnets 111 and 112. Are arranged at different positions by D / 5 in the clockwise or counterclockwise direction in FIG. Further, the submagnets 132, 133, 136, and 137 are all located at a position where n is 3 and m is 2, that is, the main magnet 111, 112 that is closer to the main magnet. Are arranged at different positions by 2D / 5 in the clockwise direction or counterclockwise direction in FIG.

  In the rotation direction R (first direction), the interval between the submagnets 131 and 132, the interval between the submagnets 132 and 133, the interval between the submagnets 133 and 134, the interval between the submagnets 135 and 136, and the interval between the submagnets 136 and 137 The intervals between the submagnets 137 and 138 are D / 5.

  Next, the magnetization directions of the plurality of main magnets and the plurality of submagnets will be described. The directions of magnetization of the plurality of main magnets, that is, the main magnets 111 and 112 are opposite to each other. In FIG. 21, circle symbols drawn in the vicinity of the main magnets 111 and 112 indicate the magnetization directions of the main magnets 111 and 112. In the present embodiment, the magnetization direction of main magnet 111 is the same as the magnetization direction (Z direction) of main magnet 11 in the first embodiment. The direction of magnetization of the main magnet 112 is the same as the direction of magnetization (−Z direction) of the main magnet 12 in the first embodiment.

  In FIG. 21, circle symbols drawn in the vicinity of the submagnets 121 to 124 and 131 to 138 indicate the magnetization directions of the submagnets 121 to 124 and 131 to 138. Each of the submagnets 121 to 124 and 131 to 138 satisfies the second or third requirement related to the magnetization direction of the submagnet described in the first embodiment. The second requirement is that the magnetization direction of the secondary magnet arranged at the position where m is 1 among the secondary magnets in each set is the same as the magnetization direction of the primary magnet closest to the secondary magnet. Is. This second requirement applies to all the submagnets 121 to 124 of the first set and some of the submagnets 131, 134, 135, and 138 of the second set. The magnetization directions of the submagnets 121 to 124, 131, 134, 135, and 138 are the same as the magnetization directions of the submagnets 21 to 24, 31, 34, 35, and 38 in the first embodiment, respectively. That is, as shown in FIG. 21, the magnetization directions of the submagnets 121, 124, 131, and 138 are the Z direction, and the magnetization directions of the submagnets 122, 123, 134, and 135 are the -Z direction. .

  The third requirement is that the direction of magnetization of the secondary magnets arranged at positions where m is 2 or more among the secondary magnets of each set is the same as that of the two secondary magnets of the same set on both sides of the secondary magnet. This is opposite to the direction of magnetization. This third requirement applies to the other part of the secondary magnets 132, 133, 136, and 137. The magnetization directions of the submagnets 132, 133, 136, and 137 are the same as the magnetization directions of the submagnets 32, 33, 36, and 37 in the first embodiment, respectively. That is, as shown in FIG. 21, the magnetization direction of the submagnets 132 and 137 is the -Z direction, and the magnetization direction of the submagnets 133 and 136 is the Z direction.

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

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. The magnetic sensor system 1 according to the present embodiment is different from the first embodiment in the following points. The magnetic sensor system 1 according to the present embodiment includes a magnetic sensor 103 instead of the magnetic sensor 3 in the first embodiment. The magnetic sensor 103 detects an applied magnetic field that is a part of an external magnetic field, and generates a detection value corresponding to applied magnetic field information that is information that the applied magnetic field has. In the present embodiment, the applied magnetic field information is the intensity of the component in one direction of the applied magnetic field. The detected value has a corresponding relationship with the intensity of the component in one direction of the applied magnetic field. Hereinafter, the detected value is represented by the symbol M.

  The external magnetic field is generated by the magnetic scale 2 as in the first embodiment. The configuration of the magnetic scale 2 is the same as that of the first embodiment. The positional relationship between the magnetic scale 2 and the magnetic sensor 103 is the same as the positional relationship between the magnetic scale 2 and the magnetic sensor 3 in the first embodiment.

  FIG. 22 is a circuit diagram showing a configuration of the first example of the magnetic sensor 103. FIG. 23 is a perspective view showing a second example of the magnetic sensor 103 and the magnetic scale 2. The applied magnetic field information in the present embodiment is, in particular, the intensity of the component in the direction parallel to the Z direction of the applied magnetic field. The component of the applied magnetic field in the direction parallel to the Z direction is the same as the second component of the applied magnetic field in the first embodiment. The detection value M has a correspondence relationship with the intensity of the component in the direction parallel to the Z direction of the applied magnetic field.

  The magnetic sensor system 1 according to the present embodiment can be used as a position detection device for detecting the relative position of the magnetic scale 2 with respect to the magnetic sensor 103. Hereinafter, the relative position of the magnetic scale 2 with respect to the magnetic sensor 103 is referred to as a relative position P2. The detected value M has a correspondence relationship with the relative position P2. When the magnetic sensor system 1 is used as a position detection device, the range of the detection value M may be a range in which the relative position P2 can be uniquely specified. Such a range of the detection value M is a range in which the detection value M does not have the same value at a plurality of relative positions P2. A specific example of the range of the detection value M will be described later.

  Next, first and second examples of the magnetic sensor 103 will be described. First, a first example of the magnetic sensor 103 will be described with reference to FIG. In the first example, the magnetic sensor 103 includes a first detection unit 171, a second detection unit 172, a power supply port V11, a ground port G11, and an output port E11. Although not shown, the first and second detection units 171 and 172 are arranged in this order in the Z direction.

  As shown in FIG. 22, the first detection unit 171 is provided between the power supply port V11 and the output port E11. The second detection unit 172 is provided between the output port E11 and the ground port G11. A power supply voltage having a predetermined magnitude is applied to the power supply port V11. The ground port G11 is connected to the ground.

  The configurations of the detection units 171 and 172 are the same as those of the detection units 71 and 73 shown in FIG. That is, each of the detectors 171 and 172 includes at least one magnetoresistive element. In FIG. 22, solid arrows indicate the direction of magnetization of the magnetization fixed layer of the magnetoresistive effect element, and white arrows indicate the direction of magnetization of the free layer of the magnetoresistive effect element.

  The magnetization direction of the magnetization fixed layer of the magnetoresistive effect element included in the first detection unit 171 is the Z direction, and the magnetization direction of the magnetization fixed layer of the magnetoresistive effect element included in the second detection unit 172 is , -Z direction. In this case, the potential of the output port E11 changes according to the intensity of the component in the direction parallel to the Z direction of the applied magnetic field.

  The magnetic sensor 103 generates a detection value M having a correspondence relationship with the intensity of the component in the direction parallel to the Z direction of the applied magnetic field, based on the potential of the output port E11. The detection value M may be the potential itself, or may be a signal normalized so that the maximum value and the minimum value of the potential are 1 and −1, respectively.

  Next, a second example of the magnetic sensor 103 will be described with reference to FIG. In the second example, the magnetic sensor 103 includes a Hall element H101. The Hall element H101 is arranged in such a posture that the magnetosensitive surface is parallel to the XY plane. In FIG. 23, the Hall element H101 is drawn larger than the actual size in order to facilitate understanding.

  Although not shown, the magnetic sensor 103 further includes a power supply port and a ground port. The Hall element H101 has a power supply terminal, a ground terminal, and two output terminals. The power supply terminal of the Hall element H101 is connected to the power supply port. The ground terminal of the Hall element H101 is connected to the ground port. A power supply voltage having a predetermined magnitude is applied to the power supply port. The ground port is connected to the ground.

  The Hall element H101 detects a component of the applied magnetic field in a direction parallel to the Z direction. The potential difference between the two output terminals of the Hall element H101 changes according to the component of the applied magnetic field in the direction parallel to the Z direction.

  The magnetic sensor 103 generates a detection value M having a correspondence relationship with the intensity of the component of the applied magnetic field in the direction parallel to the Z direction based on the potential difference between the two output terminals of the Hall element H101. The detection value M may be the potential difference itself, or may be a signal normalized so that the maximum value and the minimum value of the potential difference are 1 and −1, respectively.

  Next, the operation and effect of the magnetic sensor system 1 according to the present embodiment will be described. As described in the first embodiment, the main magnets 11 to 13 of the magnetic scale 2 generate a main magnetic field, and the sub magnets 21 to 24 and 31 to 38 of the magnetic scale 2 generate a sub magnetic field. When the ideal change in the applied magnetic field information with respect to the change in the relative position P2 is regarded as an ideal characteristic, the sub magnetic field changes the change in the applied magnetic field information with respect to the change in the relative position P2 as compared with the case where the external magnetic field is composed only of the main magnetic field. The main magnetic field is corrected so that the characteristic to be expressed approaches the ideal characteristic.

  Particularly in the present embodiment, the change in the applied magnetic field information with respect to the change in the relative position P2 is a change in the intensity of the component in the direction parallel to the Z direction of the applied magnetic field with respect to the change in the relative position P2. The ideal characteristic is an ideal change in the intensity of the component in the direction parallel to the Z direction of the applied magnetic field with respect to the change in the relative position P2, and is represented by a sine curve. Hereinafter, this sine curve is referred to as an ideal sine curve. In the present embodiment, a characteristic curve representing a change in intensity of a component in a direction parallel to the Z direction of the applied magnetic field with respect to a change in the relative position P2 is referred to as an applied magnetic field characteristic curve. The sub magnetic field corrects the main magnetic field so that the maximum deviation of the applied magnetic field characteristic curve from the ideal sine curve becomes small.

  Similar to the first embodiment, the first set of submagnets 21 to 24 reduces the third harmonic component in the applied magnetic field characteristic curve, and the second set of submagnets 31 to 38 applies the applied magnetic field. The fifth harmonic component in the characteristic curve is reduced. Thereby, in this Embodiment, compared with the case where an external magnetic field consists only of a main magnetic field, the maximum deviation of the applied magnetic field characteristic curve from an ideal sine curve becomes small. As a result, according to the present embodiment, high detection accuracy can be realized in the magnetic sensor system 1.

  Next, the applied magnetic field characteristic curve in the example of the present embodiment (hereinafter referred to as the second example) will be specifically described in comparison with the magnetic sensor system of the second comparative example. The magnetic sensor system 1 of the second example is a magnetic sensor system 1 in which the magnetic sensor system 1 according to the present embodiment is defined under the same conditions as the simulations in FIGS. 8 to 11 of the first embodiment. is there.

  The magnetic sensor system of the second comparative example includes the magnetic scale 202 of the second comparative example in which all the submagnets are removed from the magnetic scale 2 in the second embodiment. The magnetic scale 202 of the second comparative example is the same as the magnetic scale 202 of the first comparative example shown in FIG. Hereinafter, an applied magnetic field based on an external magnetic field generated by the magnetic scale 202 of the second comparative example is referred to as an applied magnetic field of the second comparative example.

  FIG. 24 is a characteristic diagram showing the applied magnetic flux density of the second comparative example, which is the magnetic flux density corresponding to the applied magnetic field of the second comparative example. FIG. 24 is obtained by simulation. The simulation conditions in FIG. 24 are the same as the simulation conditions in FIG. 13 of the first embodiment. FIG. 24 shows the applied magnetic flux density Bcz of the second comparative example. In FIG. 24, the horizontal axis represents the relative position P2, and the vertical axis represents the value of the applied magnetic flux density Bcz. The applied magnetic flux density Bcz of the second comparative example is a magnetic flux density corresponding to a component in a direction parallel to the Z direction of the applied magnetic field of the second comparative example, and the magnetic flux in the first embodiment shown in FIG. It is the same as the density Bcz.

  The applied magnetic field of the second comparative example corresponds to the applied magnetic field when the external magnetic field consists only of the main magnetic field. The applied magnetic flux density Bcz corresponds to a component in a direction parallel to the Z direction of the applied magnetic field when the external magnetic field is composed only of the main magnetic field. The curve representing the change in the applied magnetic flux density Bcz with respect to the change in the relative position P2 includes an ideal component that draws a sine curve and at least one harmonic component corresponding to the (2n-1) th order harmonic of the ideal component. It is out. A curve representing a change in applied magnetic flux density Bcz with respect to a change in relative position P2 corresponds to the applied magnetic field characteristic curve in the case where the external magnetic field is composed only of the main magnetic field.

  Next, the applied magnetic field characteristic curve in the second embodiment will be specifically described. FIG. 25 is a characteristic diagram showing an applied magnetic flux density that is a magnetic flux density corresponding to the applied magnetic field of the second embodiment. FIG. 25 is obtained by simulation. The simulation conditions in FIG. 25 are the same as the simulation conditions in FIG. 11 of the first embodiment. FIG. 25 shows the applied magnetic flux density Bz. In FIG. 25, the horizontal axis represents the relative position P2, and the vertical axis represents the value of the applied magnetic flux density Bz. The applied magnetic flux density Bz is a magnetic flux density corresponding to the component in the direction parallel to the Z direction of the applied magnetic field of the second embodiment, and is the same as the magnetic flux density Bz in the first embodiment shown in FIG. .

  As shown in FIG. 25, the curve representing the change in the applied magnetic flux density Bz with respect to the change in the relative position P2 is sine compared to the curve representing the change in the applied magnetic flux density Bcz with respect to the change in the relative position P2 shown in FIG. The curve is close to the curve. This is because, in the first embodiment, the curve representing the change in the magnetic flux density Bz with respect to the change in the relative position P2 shown in FIG. 11 shows the change in the magnetic flux density Bmz with respect to the change in the relative position P2 shown in FIG. The reason is that the curve is closer to a sine curve than the curve to be represented. As in the first embodiment, the result is that the first sub-magnetic field component generated by the first set of sub-magnets 21 to 24 and the second set of sub-magnets 31-38 generated by the second set. This shows that the third-order harmonic component and the fifth-order harmonic component of the applied magnetic field characteristic curve are reduced by the sub-magnetic field component.

  Next, with reference to FIG. 25, a specific example of the range of detection values M that can uniquely identify the relative position P2 will be described. FIG. 25 shows the movable range ST in the magnetic sensor system 1 of the second embodiment. The movable range is a predetermined range in which the relative position P2 can be changed. FIG. 24 shows the movable range ST in the magnetic sensor system of the second comparative example. The movable range ST shown in FIG. 24 is matched to the movable range ST shown in FIG.

  In the example shown in FIG. 25, the movable range ST is a range in which the intensity of the component in the direction parallel to the Z direction of the applied magnetic field increases from the minimum value to the maximum value as the relative position P2 increases. Thereby, the relative position P2 can be uniquely specified. The movable range ST may be a range narrower than the range shown in FIG. Alternatively, the movable range ST is the range shown in FIG. 25, but the range of the detection value M actually generated by the magnetic sensor 103 may be limited to a range corresponding to a range narrower than the movable range ST.

  The magnetic sensor system 1 according to the present embodiment may include the magnetic scale 2 according to the second or third embodiment instead of the magnetic scale 2 according to the first embodiment. The magnetic scale 102 according to the fourth embodiment may be provided. Further, the magnetic sensor 103 according to the present embodiment may generate a detection value having a correspondence relationship with the intensity of the applied magnetic field component in one direction other than the direction parallel to the Z direction on the XZ plane.

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

  In addition, this invention is not limited to said each embodiment, A various change is possible. As long as the requirements of the claims are satisfied, the numbers, shapes, and directions of magnetization of the plurality of main magnets and the plurality of submagnets are not limited to the examples shown in the embodiments, and are arbitrary. For example, in the fourth embodiment, the plurality of main magnets and the plurality of submagnets may have the magnetization in the radial direction of the position reference circle. In this case, the magnetic sensor 3 may be arranged on the outer side in the radial direction of the position reference circle with respect to the magnetic scale 102.

  Further, the magnetic sensor system and the magnetic scale of the present invention are not limited to the position detection device, and can also be used as a device for detecting the speed and acceleration of change in the relative position of the magnetic scale with respect to the magnetic sensor. In this case, for example, the magnetic scale includes a plurality of main magnets and a plurality of pitches from the position of the main magnet 11 to the position of the main magnet 13 of the magnetic scale 2 in the first embodiment as one pitch. A secondary magnet may be included.

  DESCRIPTION OF SYMBOLS 1 ... Magnetic sensor system, 2 ... Magnetic scale, 3 ... Magnetic sensor, 11-13 ... Main magnet, 21-24, 31-38 ... Sub magnet, 61 ... Board | substrate, 62 ... Protection part, 71 ... 1st detection part 72... Second detector 73. Third detector 74. Fourth detector 81. First detector 82. Second detector 83 83 Substrate 84 Yoke 85 , 86... Differential detector, 87... Angle calculation unit, H1 to H4. Hall element, R1 to R4.

Claims (21)

A magnetic sensor system comprising a magnetic scale for generating an external magnetic field having a spatial distribution of intensity and direction, and a magnetic sensor,
The magnetic sensor detects an applied magnetic field that is a part of the external magnetic field, and generates a detection value corresponding to applied magnetic field information that is information that the applied magnetic field has,
The magnetic scale includes a plurality of main magnets that generate a main magnetic field, and a plurality of submagnets that generate a sub-magnetic field,
The plurality of main magnets are arranged at intervals along a first direction which is a linear direction or a rotational direction,
The external magnetic field is a combination of the main magnetic field and the sub magnetic field,
The magnetic scale can change a relative position with respect to the magnetic sensor within a predetermined range along the first direction.
When the ideal change in the applied magnetic field information with respect to the change in the relative position is an ideal characteristic, the sub-magnetic field is applied with respect to the change in the relative position as compared with the case where the external magnetic field is composed only of the main magnetic field. A magnetic sensor system, wherein the main magnetic field is corrected so that a characteristic representing a change in magnetic field information approaches the ideal characteristic.   The magnetic sensor system according to claim 1, wherein the plurality of submagnets are arranged at positions different from the plurality of main magnets along the first direction.   3. The magnetism according to claim 2, wherein the plurality of submagnets are arranged such that two or more submagnets exist between two adjacent main magnets of the plurality of main magnets. Sensor system. The magnetic sensor is located away from the magnetic scale in a second direction;
4. The magnetic sensor system according to claim 1, wherein each of the plurality of main magnets and the plurality of sub-magnets has magnetization in a direction parallel to the second direction. 5. . When n is an integer of 2 or more and the external magnetic field is composed only of the main magnetic field, a curve representing a change in intensity of a component in one direction of the applied magnetic field with respect to a change in the relative position is a sine curve And at least one harmonic component corresponding to the (2n-1) th order harmonic of the ideal component,
The plurality of sub magnets constitute one or more sets of sub magnets,
5. The magnetic sensor system according to claim 1, wherein each set of sub-magnets is used to correct the main magnetic field so that one harmonic component is reduced. The plurality of main magnets are arranged at a constant interval D along the first direction,
When m is an integer equal to or greater than 1, each of the sub magnets in each set is a position between two adjacent main magnets of the plurality of main magnets, The magnetic sensor system according to claim 5, wherein the magnetic sensor system is disposed at a position different from the near main magnet by m × {1 / (2n−1)} × D in the first direction. The directions of magnetization of two adjacent main magnets of the plurality of main magnets are opposite to each other,
The direction of magnetization of a submagnet arranged at a position where m is 1 among the submagnets of each set is the same as the direction of magnetization of a main magnet closest to the submagnet. 6. The magnetic sensor system according to 6.   Of each set of secondary magnets, the direction of magnetization of the secondary magnets arranged at the position where m is 2 or more is opposite to the direction of magnetization of each of the two secondary magnets of the same set on both sides of the secondary magnet. The magnetic sensor system according to claim 7, wherein there is a magnetic sensor system.   The magnetic sensor system according to claim 1, wherein the range of the detected value is a range in which the relative position can be uniquely specified.   The magnetic sensor system according to claim 1, wherein the applied magnetic field information is an angle formed by the direction of the applied magnetic field with respect to a reference direction.   The magnetic sensor system according to claim 1, wherein the applied magnetic field information is intensity of a component in one direction of the applied magnetic field. A magnetic scale that generates an external magnetic field having a spatial distribution of intensity and direction, and a detected value corresponding to applied magnetic field information that is information that the applied magnetic field detects by detecting an applied magnetic field that is a part of the external magnetic field A magnetic scale for use in a magnetic sensor system comprising:
A plurality of main magnets that generate a main magnetic field, and a plurality of submagnets that generate a sub-magnetic field,
The plurality of main magnets are arranged at intervals along a first direction which is a linear direction or a rotational direction,
The external magnetic field is a combination of the main magnetic field and the sub magnetic field,
The magnetic scale can change a relative position with respect to the magnetic sensor within a predetermined range along the first direction.
When the ideal change in the applied magnetic field information with respect to the change in the relative position is an ideal characteristic, the sub-magnetic field is applied with respect to the change in the relative position as compared with the case where the external magnetic field is composed only of the main magnetic field. A magnetic scale, wherein the main magnetic field is corrected so that a characteristic representing a change in magnetic field information approaches the ideal characteristic.   The magnetic scale according to claim 12, wherein the plurality of submagnets are arranged at positions different from the plurality of main magnets along the first direction.   14. The magnetism according to claim 13, wherein the plurality of submagnets are arranged such that two or more submagnets exist between two adjacent main magnets of the plurality of main magnets. scale. The magnetic sensor is located away from the magnetic scale in a second direction;
The magnetic scale according to claim 12, wherein each of the plurality of main magnets and the plurality of submagnets has magnetization in a direction parallel to the second direction. When n is an integer of 2 or more and the external magnetic field is composed only of the main magnetic field, a curve representing a change in intensity of a component in one direction of the applied magnetic field with respect to a change in the relative position is a sine curve And at least one harmonic component corresponding to the (2n-1) th order harmonic of the ideal component,
The plurality of sub magnets constitute one or more sets of sub magnets,
16. The magnetic scale according to claim 12, wherein each set of submagnets is for correcting the main magnetic field so that one harmonic component is reduced. The plurality of main magnets are arranged at a constant interval D along the first direction,
When m is an integer equal to or greater than 1, each of the sub magnets in each set is a position between two adjacent main magnets of the plurality of main magnets, The magnetic scale according to claim 16, wherein the magnetic scale is arranged at a position different from the closer main magnet by m × {1 / (2n−1)} × D in the first direction. The directions of magnetization of two adjacent main magnets of the plurality of main magnets are opposite to each other,
The direction of magnetization of a submagnet arranged at a position where m is 1 among the submagnets of each set is the same as the direction of magnetization of a main magnet closest to the submagnet. The magnetic scale according to 17.   Of each set of secondary magnets, the direction of magnetization of the secondary magnets arranged at the position where m is 2 or more is opposite to the direction of magnetization of each of the two secondary magnets of the same set on both sides of the secondary magnet. The magnetic scale according to claim 18, wherein there is a magnetic scale.   The magnetic scale according to claim 12, wherein the applied magnetic field information is an angle formed by the direction of the applied magnetic field with respect to a reference direction.   20. The magnetic scale according to claim 12, wherein the applied magnetic field information is intensity of a component in one direction of the applied magnetic field.

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