Position Sensing System for Motors

Abstract

To provide a position detection system for a motor capable of expanding a detection area.SOLUTION: In a motor (300) including a coil (301) and a driving magnet (302) applying a driving magnetic field to the coil (301), a magnetized face (302a) arranged along a magnetizing direction of the driving magnet (302) faces a coil surface (301a), and a driving direction is along the magnetizing direction. The driving direction is a displacement direction of one of the coil 301 and the driving magnet (302) relative to the other. A position detection system (200) for a motor includes a magnetic sensor (100) and a processing circuit (201). The magnetic sensor (100) includes: a substrate (73); a wiring layer (W1) arranged on a substrate surface (73a) being a surface of the substrate (73); and a bias magnet (5) for applying a bias magnetic field to the wiring layer (W1). The magnetic sensor (100) is arranged so that the substrate surface (73a) is parallel to the magnetizing direction and perpendicular to the magnetized face (302a).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a motor position detection system, and more particularly to a motor position detection system used in a motor such as a VCM (Voice Coil Motor) that constitutes a camera module for a mobile device. [Background technology]

[0002] Conventionally, magnetic sensors have been widely used in mobile devices such as mobile phones, smartphones, and tablet terminals for controlling motors such as VCMs and detecting the position of pointing devices.

[0003] For example, in the pointing device described in Patent Document 1, which has a printed circuit board and a ferrite magnet, two Hall elements are placed 6 mm apart on the printed circuit board, and the position of the ferrite magnet relative to the printed circuit board (magnet position) is detected based on the output difference between the two Hall elements. The range in which position can be detected in this way (detection area) is the range in which the change in output difference with respect to magnet position becomes linear, and specifically, the range is from "-2 mm" to "+2 mm" (total of 4 mm) with the position of the ferrite magnet when the distance between the ferrite magnet and each of the two Hall elements is equal as the origin.

[0004] In addition, in a camera module for a mobile device, for example, a positional relationship between a magnet fixed to one of the lens or the camera body and a coil fixed to the other is detected by a magnetic sensor for an autofocus (A / F) VCM. Then, based on the detection result and an image from an image sensor provided in the camera body, A / F is performed by moving the lens via the VCM. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-318459 A Summary of the Invention [Problem to be solved by the invention]

[0006] If the VCM described in Patent Document 1 is used as the above-mentioned autofocus VCM, the following problem occurs. That is, in recent camera modules for smartphones and the like, lenses with longer focal lengths are being adopted as the number of lenses increases to two, three, etc. As the focal length increases, the movement range of the lens for A / F also increases, making it necessary to secure a wider detection area.

[0007] An object of the present disclosure is to provide a motor position detection system capable of expanding the detection area. [Means for solving the problem]

[0008] A motor position detection system according to an embodiment of the present disclosure is used in a motor. The motor includes a coil to which power is supplied and a drive magnet that applies a drive magnetic field to the coil. In the motor, a magnetized surface that is a surface along the magnetization direction of the drive magnet faces the coil surface of the coil, and a drive direction is along the magnetization direction. The drive direction is a direction of displacement of the other of the coil and the drive magnet relative to one of them. The motor position detection system detects the position of the other of the coil and the drive magnet relative to one of them. The motor position detection system includes a magnetic sensor and a processing circuit that processes an output signal of the magnetic sensor. The magnetic sensor is fixed to the coil and disposed in the vicinity of the coil surface and the magnetized surface, and outputs a signal according to the magnetoresistance effect caused by at least the drive magnetic field from the drive magnet. The magnetic sensor includes a substrate, a wiring layer, and a bias magnet. The substrate has a substrate surface. The substrate surface is a surface on which an X-axis and a Y-axis perpendicular to the X-axis are defined. The wiring layer is disposed along the substrate surface and includes a first half-bridge circuit and a second half-bridge circuit. The bias magnet applies a bias magnetic field to the wiring layer. The first half-bridge circuit has a pair of first magnetoresistance effect elements and a first output terminal. The pair of first magnetoresistance effect elements are half-bridge connected to detect a magnetic field along the X-axis. The first output terminal outputs a first output signal from a connection point between the pair of first magnetoresistance effect elements. The second half-bridge circuit has a pair of second magnetoresistance effect elements and a second output terminal. The pair of second magnetoresistance effect elements are half-bridge connected to detect a magnetic field along the Y-axis. The second output terminal outputs a second output signal from a connection point between the pair of second magnetoresistance effect elements. The bias magnet applies a bias magnetic field along the positive direction of the X-axis to one of the pair of first magnetoresistance effect elements and applies a bias magnetic field along the negative direction of the X-axis to the other. The bias magnet applies a bias magnetic field along the positive direction of the Y axis to one of the pair of second magnetoresistance effect elements, and applies a bias magnetic field along the negative direction of the Y axis to the other.The magnetic sensor is disposed such that the substrate surface is parallel to the magnetization direction and perpendicular to the magnetized surface. The processing circuit detects the position of the coil and the drive magnet relative to one of the coil and the drive magnet by determining the direction of a magnetic field obtained by superposing the drive magnetic field applied to the magnetic sensor and the bias magnetic field applied to the wiring layer constituting the magnetic sensor based on at least one of the first output signal and the second output signal. Effect of the Invention

[0009] The motor position detection system according to the present disclosure has an advantage that the detection area can be expanded. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1A is a front view of a motor in which a motor position detection system according to an embodiment of the present disclosure is used, and FIG. 1B is a side view of the same motor. [Diagram 2] FIG. 2 is a side view showing a positional relationship between a magnetic sensor constituting the position detection system and a mounting board for a coil constituting the motor of the above. [Diagram 3] FIG. 3 is a plan view of the magnetic sensor. [Figure 4] FIG. 4 is a schematic diagram showing a state in which the magnetic sensor is used. [Diagram 5] FIG. 5 is a cross-sectional view of a magnetoresistance effect element of the magnetic sensor. [Figure 6] FIG. 6A is an equivalent circuit diagram of a first half-bridge circuit and a third half-bridge circuit of the magnetic sensor of the above embodiment, and FIG. 6B is an equivalent circuit diagram of a second half-bridge circuit and a fourth half-bridge circuit of the magnetic sensor of the above embodiment. [Figure 7] FIG. 7 is a conceptual diagram showing the driving direction of a driving magnet constituting the motor and the direction of a driving magnetic field. [Figure 8]FIG. 8A is an explanatory diagram showing a first output signal from a first half-bridge circuit of the same, and FIG. 8B is an explanatory diagram showing a second output signal from a second half-bridge circuit of the same. [Figure 9] FIG. 9 is an explanatory diagram showing a Lissajous waveform based on the first output signal and the second output signal of the embodiment. [Figure 10] FIG. 10A is a comparative explanatory diagram showing a detection area based on two output signals (Hall sensor two phases) from two conventional Hall sensors, FIG. 10B is an explanatory diagram showing a detection area based on one of the two output signals (GMR sensor one phase) from two GMR sensors, and FIG. 10C is an explanatory diagram showing a detection area based on the calculation results for the two output signals (GMR sensor two phases) in FIG. 10B. [Figure 11] FIG. 11A is a front view showing a first modified example of the motor of the same embodiment, and FIG. 11B is a front view showing a second modified example of the motor of the same embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The figures described in the following embodiments are schematic diagrams, and the ratios of the sizes and thicknesses of the components do not necessarily reflect the actual dimensional ratios. Note that the configurations described in the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0012] (1) Overview A motor position detection system 200 according to an embodiment of the present disclosure is used for a motor 300. The motor 300 is for autofocus (A / F) of a built-in camera (camera module) of a mobile device such as a smartphone. Specifically, the motor 300 is a VCM.

[0013] However, a linear motor other than a VCM may be used as the motor 300. Note that the linear motor referred to in this embodiment is a type of motor whose driving direction (described later) is along a straight line.

[0014] (1-1) Motor The motor 300 includes a coil 301 and a drive magnet 302.

[0015] Power is supplied to the coil 301 from a power circuit, a power cable, etc. (not shown). The drive magnet 302 applies a drive magnetic field to the coil 301.

[0016] When power is supplied to the coil 301 to which the drive magnetic field from the drive magnet 302 is applied, one of the drive magnet 302 and the coil 301 is displaced with respect to the other.

[0017] (1-1-1) Drive Magnet As shown in FIGS. 1A and 1B, the drive magnet 302 in the present embodiment is a magnet with unipolar magnetization having an N pole at one end and an S pole at the other end, and has a plate shape that is long in the magnetization direction.

[0018] Note that, in the case of the magnet with unipolar magnetization as shown in FIG. 1A etc., the magnetization direction in the present embodiment is the direction of the straight line connecting the N pole and the S pole (longitudinal direction).

[0019] (1-1-2) Coil Surface and Magnetized Surface In the motor 300, the magnetized surface 302a of the drive magnet 302 faces the coil surface 301a of the coil 301.

[0020] The magnetized surface 302a in the present embodiment is a surface along the magnetization direction of the drive magnet 302 and is a surface facing the coil surface 301a. The coil surface 301a is a surface along the winding of the coil 301 (a surface perpendicular to the axis of the coil 301).

[0021] The coil surface 301a has, for example, a rectangular shape (or an oblate shape) with the direction parallel to the magnetization direction of the drive magnet 302 (the direction of the straight line connecting the N pole and the S pole) as the length (or major axis) and the direction perpendicular thereto as the width (or minor axis) as shown in FIG. 1A.

[0022] 1A, the length (major axis) of coil surface 301a is about 3 / 4 the length L (e.g., 5 mm) of magnetized surface 302a in the direction (longitudinal direction) parallel to the magnetization direction. Also, the width (minor axis) of coil surface 301a is slightly smaller than the width of magnetized surface 302a in the direction perpendicular to the magnetization direction.

[0023] 1A, the magnetized surface 302a has a rectangular shape elongated in the magnetization direction, and its size is larger than that of the coil surface 301a. Therefore, when the drive magnet 302 is located at the center of the drive area, the coil surface 301a is covered with the magnetized surface 302a.

[0024] In addition, in the direction parallel to the magnetization direction, the center line (the axis of symmetry of the magnetization direction) of the magnetized surface 302a overlaps with the center line (the axis of symmetry of the magnetization direction) of the coil surface 301a. However, the center line of the coil surface 301a may be shifted from the center line of the magnetized surface 302a (see Modification 2).

[0025] The shape of the coil surface 301a is not limited to a rectangle or an oval shape, but may be a circle or a polygon such as a hexagon.

[0026] (1-1-3) Driving direction The driving direction of the drive magnet 302 is along the magnetization direction of the drive magnet 302 as shown in FIG. 1B.

[0027] The driving direction is the direction of displacement of one of the coil 301 and the driving magnet 302 relative to the other.

[0028] As described above, the motor 300 of this embodiment is a VCM for a camera module, with the coil 301 and the drive magnet 302 being fixedly disposed relative to the camera body and the lens, respectively. Therefore, the drive direction in this embodiment is the direction of displacement of the drive magnet 302 relative to the coil 301. However, the coil 301 may be on the lens side and the drive magnet 302 on the camera body side, in which case the drive direction is the direction of displacement of the coil 301 relative to the drive magnet 302.

[0029] In this embodiment, the drive magnet 302 has a long plate shape, and the drive direction is the long direction of the drive magnet 302.

[0030] (1-1-4) Driving area The driving area is a range in which either the coil 301 or the driving magnet 302 can be displaced relative to the other.

[0031] The driving area in this embodiment is a range in which the driving magnet 302 can be displaced relative to the coil 301, and its length is approximately the same as the length of the driving magnet 302. The driving area is, for example, in the range of "-(L / 2)" to "+(L / 2)" with respect to the length L of the driving magnet 302, with the center of the longitudinal direction of the coil surface 301a as a reference. Therefore, for example, the driving area of ​​a driving magnet 302 with a length of 5 mm is "-2.5 mm" to "+2.5 mm", totaling 5 mm. However, the driving area does not have to completely match the length L of the driving magnet 302. The driving area may be, for example, within a range of ±α with respect to the length L. α is an appropriate value, for example, 5%, 10%, etc., and may be determined by experiment or simulation.

[0032] (1-2) Motor position detection system The motor position detection system 200 detects the position of one of a coil 301 and a drive magnet 302 that configure a motor 300 relative to the other. The position detected in this way is the same as the position of the lens relative to the camera body (image sensor) in the camera module.

[0033] In this embodiment, the position of the drive magnet 302 relative to the coil 301 is detected. Then, position information indicating the detection result is notified to a camera module (not shown). The position information is, for example, a coordinate on a coordinate axis (e.g., z-axis) defined along the drive direction, but may also be a moving distance.

[0034] (1-3) Camera module In the camera module, an A / F circuit (not shown) provided in the camera body (not shown) performs A / F via motor 300 based on position information notified from motor position detection system 200 and an image from an image sensor provided in the camera body, thereby moving the lens (not shown) to the focus position.

[0035] (2) Details of the motor position detection system 3, the motor position detection system 200 includes the magnetic sensor 100 and a processing circuit 201. The magnetic sensor 100 detects the magnetoresistance effect caused by a magnetic field, and outputs an output signal according to the detection result. The processing circuit 201 processes the output signal of the magnetic sensor 100.

[0036] (2-1) Sensor placement The magnetic sensor 100 is fixedly disposed relative to the coil 301. The magnetic sensor 100 is also disposed near each of the coil surface 301a of the coil 301 and the magnetized surface 302a of the drive magnet 302.

[0037] (2-1-1) Sensor position in the direction parallel to the magnetization direction (driving direction) The magnetic sensor 100 is disposed at the center of the coil surface 301a in a direction parallel to the magnetization direction when the magnetized surface 302a is viewed from the front.

[0038] (2-1-2) Position in the direction perpendicular to the magnetization direction (driving direction) Moreover, the magnetic sensor 100 is disposed in the center of the coil surface 301a in the direction perpendicular to the magnetization direction when the magnetized surface 302a is viewed from the front.

[0039] That is, the position of the magnetic sensor 100 in this embodiment is the center of the coil surface 301a in two directions parallel and perpendicular to the magnetization direction. Note that the center here refers to the intersection of the diagonals when the shape of the coil surface 301a is rectangular, and the center when the shape is oval, but it may also be near the intersection or center. The vicinity may mean that the distance from the intersection or center is within a threshold range. The threshold may be, for example, 5% or less of the length of the diagonal, 1 / 10 times the major axis of the oval, or any other appropriate value.

[0040] (2-1-3) Number of sensors In this embodiment, as shown in FIG. 1A, only one magnetic sensor 100 is disposed with respect to the coil 301 at the position as described above.

[0041] Although details will be described later, even if there is only one magnetic sensor 100, by arranging the magnetic sensor 100 in the following orientation with respect to the magnetized surface 302a, it is possible to ensure a detection area larger than that described in Patent Document 1. Furthermore, by arranging only one magnetic sensor 100 (the number of sensors is one), no phase shift (phase shift of output signals due to mounting errors or individual differences) occurs, which is likely to occur when arranging two or more magnetic sensors, and therefore detection accuracy is improved.

[0042] (2-1-4) Sensor attitude The magnetic sensor 100 is disposed so that the substrate surface 73a is parallel to the magnetization direction and perpendicular to the magnetized surface 302a.

[0043] Note that the parallel and perpendicular mentioned here do not have to be completely parallel and completely perpendicular. For example, a range of ±θ degrees from completely parallel and completely perpendicular may be considered as parallel and perpendicular. θ is, for example, 5 degrees, 2 degrees, etc., but is not limited to these.

[0044] Furthermore, in this embodiment, the driving direction is parallel to the magnetization direction, and the substrate surface 73a being parallel to the magnetization direction is the same as the substrate surface 73a being parallel to the driving direction.

[0045] 2, in this embodiment, the magnetic sensor 100 is provided on a mounting board 303. That is, the motor 300 further includes a mounting board 303. The mounting board 303 is a board on which the coil 301 is mounted, and has a mounting surface 303a facing the coil surface 301a.

[0046] The magnetic sensor 100 is provided on the mounting board 303 so that the base surface 73a is perpendicular to the mounting surface 303a. This allows the magnetic sensor 100 to be fixed to the coil 301 in the above-mentioned position and with the correct attitude.

[0047] (2-1-5) Sensor function and structure The magnetic sensor 100 detects the magnetoresistance effect caused by the drive magnetic field from the drive magnet 302, and outputs a signal according to the detection result. However, the output signal of the magnetic sensor 100 is also affected by a bias magnetic field from a bias magnet 5 (described later) constituting the magnetic sensor 100.

[0048] The magnetoresistance effect detected by the magnetic sensor 100 is preferably the giant magneto resistive (GMR) effect or the tunnel magneto resistive (TMR) effect, but may also be the anisotropic magneto resistive (AMR) effect. The magnetoresistance effect detected in this embodiment is the GMR effect.

[0049] The magnetic sensor 100 includes a substrate 73, a wiring layer W1, and a bias magnet 5.

[0050] The substrate 73 has a substrate surface 73a. The substrate surface 73a is a surface on which an X-axis and a Y-axis perpendicular to the X-axis are defined. The substrate 73 is usually plate-shaped, but the shape thereof is not limited.

[0051] The wiring layer W1 is disposed along the substrate surface 73a. The bias magnet 5 applies a bias magnetic field to the wiring layer W1.

[0052] The wiring layer W1 includes a first half-bridge circuit 1 and a second half-bridge circuit 2.

[0053] The first half-bridge circuit 1 has a pair of first magnetoresistance effect elements 1P, 1Q and a first output terminal 1T. The pair of first magnetoresistance effect elements 1P, 1Q are half-bridge connected to detect a magnetic field along the X-axis. The first output terminal 1T outputs a first output signal from a connection point between the pair of first magnetoresistance effect elements 1P, 1Q.

[0054] The second half-bridge circuit 2 has a pair of second magnetoresistance effect elements 2P, 2Q and a second output terminal 2T. The pair of second magnetoresistance effect elements 2P, 2Q are half-bridge connected to detect a magnetic field along the Y-axis. The second output terminal 2T outputs a second output signal from a connection point between the pair of second magnetoresistance effect elements 2P, 2Q.

[0055] In addition, the wiring layer W1 in this embodiment further includes a third half-bridge circuit 3 that outputs a third output signal having a phase opposite to that of the first output signal, and a fourth half-bridge circuit 4 that outputs a fourth output signal having a phase opposite to that of the second output signal (see "Details of the magnetic sensor").

[0056] The bias magnet 5 applies a bias magnetic field along the positive direction of the X-axis to one of the pair of first magnetoresistance effect elements 1P, 1Q, and applies a bias magnetic field along the negative direction of the X-axis to the other.

[0057] Moreover, the bias magnet 5 applies a bias magnetic field along the positive direction of the Y axis to one of the pair of second magnetoresistance effect elements 2P, 2Q, and applies a bias magnetic field along the negative direction of the Y axis to the other.

[0058] As described above, the magnetic sensor 100 is disposed so that the substrate surface 73a is parallel to the magnetization direction (driving direction) and perpendicular to the magnetized surface 302a. As a result, the first output signal and the second output signal (see FIGS. 8A and 8B) outputted from the first output terminal 1T and the second output terminal 2T, respectively, in response to the displacement (linear movement along the driving direction) of the driving magnet 302 approach a sine waveform and a cosine waveform, respectively, as the driving magnetic field (see FIG. 7) from the driving magnet 302 and the bias magnetic field (see FIG. 3) from the bias magnet 5 are superimposed on each other (see FIGS. 8A and 8B).

[0059] In detail, in Figure 7, for a driving magnet 302 having a length L of 5 mm in the magnetization direction (z-axis direction), the directions of the driving magnetic field at multiple positions spaced the same distance (1 mm from the magnetized surface 302a) in a direction perpendicular to the magnetization direction (x-axis direction) and 0.2 mm apart in a direction parallel to the magnetization direction (z-axis direction) are shown by white arrows.

[0060] In FIG. 7, a number of marks each having an x ​​inside a circle indicate a number of positions as described above.

[0061] Further, a coordinate system (right-handed system) is defined for the motor 300, which includes the z-axis, x-axis, and y-axis perpendicular to the z-axis and x-axis.

[0062] The z-axis, x-axis, and y-axis defined for the motor 300 correspond to the X-axis, Y-axis, and Z-axis defined for the magnetic sensor 100 (see FIGS. 3 and 5), respectively.

[0063] In other words, in the motor position detection system 200, the magnetic sensor 100 is disposed with respect to the driving magnet 302 in such an orientation that the X-axis, Y-axis, and Z-axis defined as shown in FIG. 5 along the substrate surface 73a correspond to the z-axis, x-axis, and y-axis defined as shown in FIG. 7 along the magnetized surface 302a, respectively.

[0064] By positioning the magnetic sensor 100 in the above-described orientation relative to the drive magnet 302, the magnetic sensor 100 detects a magnetic field that is a superposition of the drive magnetic field as indicated by the white arrow in FIG. 7 and the bias magnetic field as indicated by the dotted line in FIG. 3.

[0065] As shown in FIG. 7, the direction of the driving magnetic field generated by driving magnet 302 changes from the position beyond the end on the N-pole side (the top mark) to the position just before the end on the S-pole side (the bottom mark) in the following ways: approximately the same as the z-axis, midway between the z-axis and the x-axis, approximately the same as the x-axis, midway between the x-axis and the opposite direction of the z-axis, approximately the same as the opposite direction of the z-axis, midway between the opposite direction of the z-axis and the opposite direction of the x-axis, approximately the same as the opposite direction of the x-axis, midway between the z-axis and the opposite direction of the x-axis, and approximately the same as the z-axis.

[0066] Therefore, the signal waveforms of the first output signal and the second output signal output from the first output terminal 1T and the second output terminal 2T, respectively, in response to the displacement of the drive magnet 302 will be as shown by the solid lines in Figures 8A and 8B, respectively.

[0067] In Figures 8A and 8B, the horizontal axis indicates the normalized position (position when the length L of the driving magnet 302 is 1 mm) from a reference point (the center of the driving magnet 302) in the magnetization direction, and the vertical axis indicates the normalized component of the first output signal (value when the length L is 1 mm).

[0068] In Fig. 8A, the waveform of the first output signal shown by the solid line is approximately consistent with the sine waveform shown by the dotted line within the range of positions "-0.5" to "+0.5". Also, in Fig. 8B, the waveform of the second output signal shown by the solid line is approximately consistent with the cosine waveform shown by the dotted line within the range of positions "-0.5" to "+0.5".

[0069] Therefore, when L=5 mm, within a range of "-2.5 mm" to "+2.5 mm" (total of 5 mm) with respect to the reference point, the waveforms of the first output signal and the second output signal will approximately match a sine waveform and a cosine waveform, respectively.

[0070] The waveform shown by the solid line in Fig. 9 is a Lissajous waveform corresponding to the first output signal and the second output signal having the above-mentioned waveforms. This Lissajous waveform is approximately identical to the ideal Lissajous waveform (part of a circle) shown by the dotted line in Fig. 9, with the X component in the range of "0" to "1" and the Y component in the range of "0" to "0.5".

[0071] Therefore, when the motor position detection system 200 in this embodiment is used for a motor 300 (A / F VCM of a camera module) having a drive magnet 302 with L = 5 mm, for example, it is capable of highly accurate position detection within the range of "-2.5 mm" to "+2.5 mm" (total of 5 mm).

[0072] (2-2) Signal Processing The processing circuit 201 determines the direction of a magnetic field formed by superimposing a driving magnetic field applied to the magnetic sensor 100 and a bias magnetic field applied to the wiring layer W1 that constitutes the magnetic sensor 100, based on at least one of the first output signal and the second output signal.

[0073] In this embodiment, the processing circuit 201 uses both the first output signal and the second output signal to determine the direction of such a magnetic field. In detail, the processing circuit 201 performs an arctangent operation on the first output signal and the second output signal, and determines the direction of the magnetic field based on the result of the arctangent operation. This makes it possible to ensure a wider detection area (approximately the same size as the driving area) compared to the case where only one of the first output signal and the second output signal is used.

[0074] Fig. 10B shows the detection area when only one of the first and second output signals (for example, the first output signal) is used (GMR sensor 1-phase), and Fig. 10C shows the detection area when both are used (GMR sensor 2-phase). For comparison, Fig. 10A shows the detection area when two Hall elements are used (Hall sensor 2-phase: corresponding to the background art).

[0075] The detection area for a two-phase Hall sensor is the range obtained by connecting the approximately straight line portions of each of the two phases, as shown in Figure 10A, and specifically, the range is from "-2mm" to "+2mm" (4mm in total) with the driving area being from "-3mm" to "+3mm".

[0076] In contrast, the detection area for a single-phase GMR sensor is the portion of the range from the maximum value to the minimum value of the sine waveform that is located above the cosine waveform, as shown in FIG. 10B. Specifically, for example, the range is from "-2.5 mm" to "+0.5 mm" (3 mm in total) relative to the driving area of ​​"-2.5 mm" to "+2.5 mm".

[0077] The detection area in the case of a two-phase GMR sensor is substantially the entire arctangent (atan) waveform, as shown in FIG. 10C, and specifically, for example, the range from "-2.5 mm" to "+2.5 mm" (5 mm in total) for a driving area of ​​"-2.5 mm" to "+2.5 mm".

[0078] The processing circuit 201 detects the position of one of the coil 301 and the drive magnet 302 relative to the other (in this embodiment, the position of the drive magnet 302 relative to the coil 301) based on the direction of the magnetic field determined as described above.

[0079] This makes it possible to provide a motor position detection system 200 that can expand the detection area.

[0080] According to this embodiment, the waveforms of the first output signal and the second signal output in accordance with the movement of the driving magnetic field applied to the magnetic sensor 100 become waveforms close to an ideal sine wave and waveforms close to an ideal cosine wave due to the bias magnetic field. Therefore, it is possible to accurately determine the direction of the magnetic field applied to the magnetic sensor 100 based on the first output signal and the second output signal.

[0081] Note that, in addition to the first output signal and the second output signal, the processing circuit 201 in the present embodiment can also perform position detection using a third output signal and a fourth output signal (see "Details of the Processing Circuit").

[0082] Hereinafter, in addition to the X-axis and the Y-axis, a Z-axis (right-handed system), which is an axis orthogonal to both the X-axis and the Y-axis, will be further used for explanation. The X-axis, Y-axis, and Z-axis are each virtual axes set on the magnetic sensor 100 (for example, the substrate surface 73a which is the surface of the substrate 73), and are not physical configurations.

[0083] (3) Details of the Magnetic Sensor (3-1) Overall Configuration As shown in FIGS. 3 to 5, the magnetic sensor 100 includes a second protective film 72, a bias magnet 5, a first protective film 71, a wiring layer W1, and a substrate 73. The wiring layer W1 includes a first half-bridge circuit 1, a second half-bridge circuit 2, a third half-bridge circuit 3, and a fourth half-bridge circuit 4. Note that, in FIG. 3, only the wiring layer W1 and the bias magnet 5 are illustrated, and in FIG. 4, only the wiring layer W1 is illustrated.

[0084] The motor position detection system 200 includes a magnetic sensor 100 and a processing circuit 201. The processing circuit 201 obtains the direction of the magnetic field applied to the magnetic sensor 100 based on at least the first output signal and the second output signal.

[0085] (3-2) Bias Magnet As shown in FIGS. 3 and 5, the shape of the bias magnet 5 is a rectangular parallelepiped. The bias magnet 5 is a single member. As the bias magnet 5, for example, a permanent magnet or an electromagnet can be adopted. The bias magnet 5 in the present embodiment is a permanent magnet. The bias magnet 5 is, for example, a ferrite magnet or a neodymium magnet.

[0086] The bias magnet 5 has a plurality of (eight in this embodiment) magnetic poles 50. Four of the eight magnetic poles 50 are arranged on a first plane parallel to both the X-axis and the Y-axis. The remaining four of the eight magnetic poles 50 are arranged on a second plane parallel to the first plane.

[0087] That is, two sets of four magnetic poles 50 are provided, and in each set, the four magnetic poles 50 are provided on the same plane. The magnetic poles 50 belonging to different sets are provided at different positions in the Z-axis direction. The Z coordinates of the four magnetic poles 50 shown in FIG. 3 are greater than the Z coordinates of the remaining four magnetic poles 50.

[0088] The eight magnetic poles 50 are arranged such that adjacent magnetic poles 50 in the X-axis direction have different poles, and adjacent magnetic poles 50 in the Y-axis direction have different poles. Also, the eight magnetic poles 50 are arranged such that adjacent magnetic poles 50 in the Z-axis direction have different poles. The panels are arranged so that

[0089] (3-3) Base material As shown in FIG. 5, the base material 73 has a plate-like shape. The base material 73 is, for example, an alumina substrate. In this embodiment, one of the two main surfaces of the base material 73 (for example, the side opposite to the side on which the wiring layer W1 is formed) is referred to as the "base material surface 73a." The X-axis and the Y-axis are defined along the base material surface 73a. However, the X-axis and the Y-axis may be defined along the other of the two main surfaces of the base material 73 (the side on which the wiring layer W1 is formed), in which case the other main surface is referred to as the "base material surface 73a."

[0090] (3-4) Wiring layer 5, the wiring layer W1 is formed on a surface of the base material 73 (the other of the two main surfaces that is not the base material surface 73a). In this way, the base material 73 holds the wiring layer W1. The wiring layer W1 of this embodiment includes multiple layers. The multiple layers are electrically connected to each other via through holes.

[0091] 4, the wiring layer W1 includes a first half-bridge circuit 1, a second half-bridge circuit 2, a third half-bridge circuit 3, and a fourth half-bridge circuit 4. The first half-bridge circuit 1 has a pair of first magnetoresistance effect elements 1P, 1Q and a first output terminal 1T. The second half-bridge circuit 2 has a pair of second magnetoresistance effect elements 2P, 2Q and a second output terminal 2T.

[0092] As shown in Fig. 6A, the third half-bridge circuit 3 has a pair of third magnetoresistance effect elements 3P, 3Q and a third output terminal 3T. The pair of third magnetoresistance effect elements 3P, 3Q are half-bridge connected. The pair of third magnetoresistance effect elements 3P, 3Q detect a magnetic field along the X-axis. The third output terminal 3T outputs a third output signal from a connection point between the pair of third magnetoresistance effect elements 3P, 3Q.

[0093] As shown in Fig. 6B, the fourth half-bridge circuit 4 has a pair of fourth magnetoresistance effect elements 4P, 4Q and a fourth output terminal 4T. The pair of fourth magnetoresistance effect elements 4P, 4Q are half-bridge connected. The pair of fourth magnetoresistance effect elements 4P, 4Q detect a magnetic field along the Y-axis. The fourth output terminal 4T outputs a fourth output signal from a connection point between the pair of fourth magnetoresistance effect elements 4P, 4Q.

[0094] Hereinafter, the first magnetoresistance effect elements 1P, 1Q, the second magnetoresistance effect elements 2P, 2Q, the third magnetoresistance effect elements 3P, 3Q, and the fourth magnetoresistance effect elements 4P, 4Q may each be referred to as magnetoresistance effect element Mr0. That is, the magnetic sensor 100 includes multiple (eight) magnetoresistance effect elements Mr0.

[0095] 4, the wiring layer W1 further includes power terminals H10, H20 and reference terminals L10, L20. The power terminals H10, H20 are high-potential side terminals electrically connected to a high-potential side electric circuit of the power supply. The reference terminals L10, L20 are low-potential side terminals electrically connected to a low-potential side electric circuit (a reference potential electric circuit) of the power supply. In this embodiment, the reference terminals L10, L20 are ground terminals electrically connected to a ground potential electric circuit.

[0096] A first terminal of the first magnetoresistance effect element 1P is electrically connected to the reference terminal L20. A second terminal of the first magnetoresistance effect element 1P is electrically connected to a first terminal of the first magnetoresistance effect element 1Q. A second terminal of the first magnetoresistance effect element 1Q is electrically connected to a power supply terminal H10. A first output terminal 1T is electrically connected to a connection point between the pair of first magnetoresistance effect elements 1P and 1Q.

[0097] A first terminal of the second magnetoresistance effect element 2P is electrically connected to a power supply terminal H10. A second terminal of the second magnetoresistance effect element 2P is electrically connected to a first terminal of the second magnetoresistance effect element 2Q. A second terminal of the second magnetoresistance effect element 2Q is electrically connected to a reference terminal L10. The second output terminal 2T is electrically connected to a connection point between the pair of second magnetoresistance effect elements 2P, 2Q.

[0098] A first terminal of the third magnetoresistance effect element 3P is electrically connected to a power supply terminal H20. A second terminal of the third magnetoresistance effect element 3P is electrically connected to a first terminal of the third magnetoresistance effect element 3Q. A second terminal of the third magnetoresistance effect element 3Q is electrically connected to a reference terminal L10. The third output terminal 3T is electrically connected to a connection point between the pair of third magnetoresistance effect elements 3P and 3Q.

[0099] A first terminal of the fourth magnetoresistance effect element 4P is electrically connected to the reference terminal L20. A second terminal of the fourth magnetoresistance effect element 4P is electrically connected to a first terminal of the fourth magnetoresistance effect element 4Q. A second terminal of the fourth magnetoresistance effect element 4Q is electrically connected to the power supply terminal H20. The fourth output terminal 4T is electrically connected to a connection point between the pair of fourth magnetoresistance effect elements 4P and 4Q.

[0100] The first output terminal 1T, the second output terminal 2T, the third output terminal 3T, and the fourth output terminal 4T are electrically connected to the processing circuit 201. For simplification, in Fig. 3 and Fig. 4, only the first output terminal 1T is illustrated as being connected to the processing circuit 201.

[0101] 3, 4, 6A, and 6B, the shape of the magnetoresistive element Mr0 is illustrated as a rectangle when viewed from the Z-axis direction. However, this shape is merely a schematic diagram illustrating the orientation of the magnetoresistive element Mr0, and does not necessarily match the actual shape of the magnetoresistive element Mr0.

[0102] The electrical resistance value of the magnetoresistance effect element Mr0 changes depending on the magnitude of the applied magnetic field. The magnetic sensor 100 outputs the change in the electrical resistance value of the magnetoresistance effect element Mr0 as a voltage signal. The magnetoresistance effect element Mr0 has no sensitivity to magnetic fields in a first direction (a direction along the long side in FIG. 3) and has sensitivity to magnetic fields in a second direction (a direction along the short side in FIG. 3). The sensitivity of the magnetoresistance effect element Mr0 is maximum to magnetic fields in the second direction.

[0103] The pair of first magnetoresistance effect elements 1P, 1Q and the pair of third magnetoresistance effect elements 3P, 3Q are arranged so as to have sensitivity to a magnetic field in a direction along the X-axis. The pair of first magnetoresistance effect elements 1P, 1Q and the pair of third magnetoresistance effect elements 3P, 3Q exhibit the same change in resistance value when a magnetic field in the positive direction of the X-axis and a magnetic field in the negative direction of the X-axis have the same magnetic field magnitude.

[0104] The pair of second magnetoresistance effect elements 2P, 2Q and the pair of fourth magnetoresistance effect elements 4P, 4Q are arranged so as to have sensitivity to a magnetic field in a direction along the Y-axis. The pair of second magnetoresistance effect elements 2P, 2Q and the pair of fourth magnetoresistance effect elements 4P, 4Q exhibit the same change in resistance value when a magnetic field along the positive direction of the Y-axis and a magnetic field along the negative direction of the Y-axis have the same magnetic field magnitude.

[0105] When viewed from the Z-axis direction, with the center of the magnetic sensor 100 as a reference, the magnetoresistance effect elements Mr0 are arranged as follows: the first magnetoresistance effect element 1P and the third magnetoresistance effect element 3P are arranged on the positive side of the Y-axis from the center; the first magnetoresistance effect element 1Q and the third magnetoresistance effect element 3Q are arranged on the negative side of the Y-axis from the center; The second magnetoresistance effect element 2P and the fourth magnetoresistance effect element 4P are disposed on the positive side of the X-axis from the center, and the second magnetoresistance effect element 2Q and the fourth magnetoresistance effect element 4Q are disposed on the negative side of the X-axis from the center.

[0106] As described above, the Z coordinates of the four magnetic poles 50 shown in Fig. 3 are greater than the Z coordinates of the remaining four magnetic poles 50. In other words, of the multiple magnetic poles 50 of the bias magnet 5, the four magnetic poles 50 shown in Fig. 3 face the multiple magnetoresistance effect elements Mr0 and apply a bias magnetic field to the multiple magnetoresistance effect elements Mr0. In Fig. 3, the direction of the bias magnetic field is indicated by an arrow.

[0107] A bias magnetic field along the positive direction of the X-axis is applied to the first magnetoresistance effect element 1P and the third magnetoresistance effect element 3P. A bias magnetic field along the negative direction of the X-axis is applied to the first magnetoresistance effect element 1Q and the third magnetoresistance effect element 3Q.

[0108] A bias magnetic field along the positive direction of the Y-axis is applied to the second magnetoresistance effect element 2P and the fourth magnetoresistance effect element 4P. A bias magnetic field along the negative direction of the Y-axis is applied to the second magnetoresistance effect element 2Q and the fourth magnetoresistance effect element 4Q.

[0109] In this way, the single bias magnet 5 generates a bias magnetic field along the positive direction of the X-axis and a bias magnetic field along the negative direction of the X-axis. Furthermore, the single bias magnet 5 also generates a bias magnetic field along the positive direction of the Y-axis and a bias magnetic field along the negative direction of the Y-axis.

[0110] The magnetoresistance effect element Mr0 in this embodiment is a GMR element. More specifically, the magnetoresistance effect element Mr0 is a CIP (current in plane) type GMR element. However, the magnetoresistance effect element Mr0 may be a TMR element.

[0111] The magnetoresistance effect element Mr0 may be an AMR element, but since GMR elements and TMR elements have higher sensitivity than AMR elements, using a GMR element or TMR element as the magnetoresistance effect element Mr0 can improve the detection accuracy of the motor position detection system 200.

[0112] The magnetoresistance effect element Mr0 has no sensitivity in a predetermined direction, and has isotropic sensitivity in a direction intersecting the predetermined direction.

[0113] The bias magnet 5 applies a magnetic field (bias magnetic field) having an intensity equal to or less than half the anisotropic magnetic field of each of the magnetoresistance effect elements Mr0 to each of the multiple (eight) magnetoresistance effect elements Mr0, including the pair of first magnetoresistance effect elements 1P, 1Q and the pair of second magnetoresistance effect elements 2P, 2Q, thereby making it possible to suppress distortion of the output waveform of each of the multiple magnetoresistance effect elements Mr0.

[0114] (3-5) Protective film 5, the first protective film 71 covers the wiring layer W1. The bias magnet 5 is mounted on the surface of the first protective film 71. The second protective film 72 covers the bias magnet 5.

[0115] (4) Details of the processing circuit The processing circuit 201 (see FIG. 3) includes a computer system having one or more processors and a memory. The functions of the processing circuit 201 are realized by the processor of the computer system executing a program recorded in the memory of the computer system. The program may be recorded in the memory, or may be provided via a telecommunication line such as the Internet, or may be provided by recording it on a non-transitory recording medium such as a memory card.

[0116] The processing circuit 201 determines the direction of the magnetic field (magnetic field obtained by superposing the driving magnetic field and the bias magnetic field) applied to the magnetic sensor 100 based on the first output signal, the second output signal, the third output signal, and the fourth output signal. The first output signal, the second output signal, the third output signal, and the fourth output signal are signals output from the first output terminal 1T, the second output terminal 2T, the third output terminal 3T, and the fourth output terminal 4T, respectively. In other words, the first output signal, the second output signal, the third output signal, and the fourth output signal are signals output from the first half-bridge circuit 1, the second half-bridge circuit 2, the third half-bridge circuit 3, and the fourth half-bridge circuit 4, respectively.

[0117] 3 and 6A, the first half-bridge circuit 1 and the third half-bridge circuit 3 have the same sensitivity direction of the magnetoresistance element Mr0 and the same direction of the applied bias magnetic field, but the relationship between the high potential side and the low potential side is opposite to each other. Therefore, the third output signal is a signal of opposite phase to the first output signal.

[0118] 3 and 6B, the sensitivity direction of the magnetoresistance element Mr0 and the direction of the applied bias magnetic field are the same, but the relationship between the high potential side and the low potential side is opposite to each other. Therefore, the fourth output signal is a signal of opposite phase to the second output signal.

[0119] (5) Detection of magnetic field direction The magnetic sensor 100 is placed near the drive magnet 302. The north and south poles of the drive magnet 302 form a magnetic field. The direction of the magnetic field applied to the magnetic sensor 100 changes with the linear movement of the drive magnet 302 along the magnetization direction. The processing circuit 201 determines the direction of the magnetic field applied to the magnetic sensor 100 based on the output of the magnetic sensor 100.

[0120] As the position of the drive magnet 302 relative to the coil 301 changes parallel to the magnetization direction, the first output signal, the second output signal, the third output signal, and the fourth output signal each change in a sine wave or cosine wave manner.

[0121] The phases of the first output signal and the second output signal correspond to the direction of the magnetic field applied to the magnetic sensor 100. That is, the processing circuit 201 can determine the direction of the magnetic field applied to the magnetic sensor 100 based on the first output signal and the second output signal. More specifically, the processing circuit 201 can determine the direction of the magnetic field applied to the magnetic sensor 100 in the range of "-L / 2" to "+L / 2" with respect to the length L (e.g., 5 mm) of the driving magnet 302.

[0122] As another example, the processing circuit 201 may perform position detection based on the third output signal and the fourth output signal in addition to the first output signal and the second output signal.

[0123] Specifically, the processing circuit 201 generates a first differential signal which is a differential signal between the first output signal and the third output signal. The waveform of the first differential signal is a waveform in which the amplitude is doubled in the first output signal. Furthermore, the processing circuit 201 generates a second differential signal which is a differential signal between the second output signal and the fourth output signal. The waveform of the second differential signal is a waveform in which the amplitude is doubled in the second output signal.

[0124] The processing circuit 201 determines a common phase between the first differential signal as a sine wave and the second differential signal as a cosine wave based on the first differential signal and the second differential signal, and can detect the position of the drive magnet 302 relative to the coil 301 (i.e., the position of the lens relative to the camera body) based on the determined phase. The first differential signal and the second differential signal have twice the amplitude compared to the first output signal and the second output signal, so that position detection can be performed with higher accuracy.

[0125] (6) Variation 1 As described above, in the motor position detection system 200 of the embodiment, even if the position of the magnetic sensor 100 is shifted from the center of the coil surface 301a in the direction perpendicular to the magnetization direction, the effect on the detection accuracy (size of the detection area) is small.

[0126] Therefore, in motor position detection system 200 of Modification 1, as shown in FIG. 11A, magnetic sensor 100 is disposed outside coil surface 301a in a direction perpendicular to the magnetization direction when magnetized surface 302a is viewed from the front.

[0127] The magnetic sensor 100 may be spaced from the coil 301 in a direction perpendicular to the magnetization direction, for example, to a distance approximately equal to the length L (eg, 5 mm) of the drive magnet 302 in the magnetization direction.

[0128] The position of the magnetic sensor 100 in the direction perpendicular to the magnetization direction is the center of the coil surface 301a, as in the embodiment. Other matters may be the same as in the embodiment.

[0129] According to the first modification, it is possible to improve the degree of freedom in arranging the magnetic sensor 100 while maintaining the detection accuracy.

[0130] (7) Variation 2 In the motor position detection system 200 of the second variant, the magnetic sensor 100 is provided outside the coil surface 301a and inside the magnetized surface (302a) in the direction perpendicular to the magnetization direction when viewing the magnetized surface 302a from the front, as shown in FIG. 11B.

[0131] Therefore, the driving magnet 302 of the second modification has a larger size (width) in the direction perpendicular to the magnetization direction than the driving magnet 302 of the embodiment (see FIG. 1A) or the driving magnet 302 of the first modification (see FIG. 11A).

[0132] That is, in the second modification, the size (width) of the magnetized surface 302a is larger than the size (minor axis) of the coil surface 301a in the direction perpendicular to the magnetization direction, to the extent that the magnetic sensor 100 is located inside the magnetized surface 302a.

[0133] 11B, in the second modification, the center line of the magnetized surface 302a is shifted toward the magnetic sensor 100 from the center line of the coil surface 301a in the direction parallel to the magnetization direction. This makes the size (width) of the magnetized surface 302a smaller than when the two center lines overlap. However, the center line of the magnetized surface 302a may coincide with the center line of the coil surface 301a.

[0134] According to the second modification, it is possible to further improve the detection accuracy.

[0135] (8) Other modifications The driving magnet 302 is not limited to a single-pole magnetized magnet as shown in FIG. 1A etc., but may be a multi-pole magnetized magnet in which N poles and S poles are arranged alternately.

[0136] Furthermore, the application of the motor position detection system is not limited to detecting the position of a detection target (the position of the drive magnet 302 relative to the coil 301 in this embodiment and modifications 1 and 2). The magnetic sensor 100 may be used, for example, to detect the moving distance of a detection target.

[0137] Furthermore, the magnetic sensor 100 may be used in, for example, a rotary motor (not shown) having a coil and a rotor, and may detect the rotation angle and rotation speed of one of the coil and the rotor relative to the other. The rotor is a ring-shaped magnetized multi-pole magnet in which N poles and S poles are alternately arranged along the circumferential direction. In the case of the rotor, the direction along the arrangement of the magnetic poles (circumferential direction) is the magnetization direction (driving direction).

[0138] (9) Summary The motor position detection system (200) according to the first aspect is used in a motor (300). The motor (300) includes a coil (301) to which power is supplied, and a drive magnet (302) that applies a drive magnetic field to the coil (301). In the motor (300), a magnetized surface (302a) that is a surface along the magnetization direction of the drive magnet (302) faces a coil surface (301a) of the coil (301), and a drive direction is along the magnetization direction. The drive direction is a direction of displacement of one of the coil (301) and the drive magnet (302) relative to the other. The motor position detection system (200) detects the position of the other of the coil (301) and the drive magnet (302) relative to one of them.

[0139] The motor position detection system (200) includes a magnetic sensor (100) and a processing circuit (201) for processing an output signal of the magnetic sensor (100). The magnetic sensor (100) is fixed to the coil (301) and disposed in the vicinity of the coil surface (301a) and the magnetized surface (302a), and outputs a signal according to the magnetoresistance effect caused by at least the driving magnetic field from the driving magnet (302).

[0140] The magnetic sensor (100) includes a substrate (73), a wiring layer (W1), and a bias magnet (5). The substrate (73) has a substrate surface (73a). The substrate surface (73a) is a plane on which an X-axis and a Y-axis perpendicular to the X-axis are defined. The wiring layer (W1) is disposed along the substrate surface (73a) and includes a first half-bridge circuit (1) and a second half-bridge circuit (2). The bias magnet (5) applies a bias magnetic field to the wiring layer (W1).

[0141] The first half-bridge circuit (1) has a pair of first magnetoresistance effect elements (1P, 1Q) and a first output terminal (1T). The pair of first magnetoresistance effect elements (1P, 1Q) are half-bridge connected and detect a magnetic field along the X-axis. The first output terminal (1T) outputs a first output signal from a connection point between the pair of first magnetoresistance effect elements (1P, 1Q). The second half-bridge circuit (2) has a pair of second magnetoresistance effect elements (2P, 2Q) and a second output terminal (2T). The pair of second magnetoresistance effect elements (2P, 2Q) are half-bridge connected and detect a magnetic field along the Y-axis. The second output terminal (2T) outputs a second output signal from a connection point between the pair of second magnetoresistance effect elements (2P, 2Q).

[0142] The bias magnet (5) applies a bias magnetic field along the positive direction of the X-axis to one of the pair of first magnetoresistance effect elements (1P, 1Q) and applies a bias magnetic field along the negative direction of the X-axis to the other. The bias magnet (5) also applies a bias magnetic field along the positive direction of the Y-axis to one of the pair of second magnetoresistance effect elements (2P, 2Q) and applies a bias magnetic field along the negative direction of the Y-axis to the other.

[0143] The magnetic sensor (100) is disposed such that the substrate surface (73a) is parallel to the magnetization direction and perpendicular to the magnetized surface (302a). The processing circuit (201) detects the position of one of the coil (301) and the drive magnet (302) relative to the other by determining the direction of a magnetic field obtained by superposing the drive magnetic field applied to the magnetic sensor (100) and the bias magnetic field applied to the wiring layer (W1) constituting the magnetic sensor (100) based on at least one of the first output signal and the second output signal.

[0144] According to this aspect, it is possible to provide a motor position detection system capable of expanding the detection area.

[0145] In addition, since the device described in Patent Document 1 uses two Hall elements, a phase shift between output signals is likely to occur due to errors in the mounting position when mounting each Hall element on a printed circuit board or individual differences between the Hall elements, which may result in a decrease in the accuracy of position detection.

[0146] In the motor position detection system (200) according to the second aspect, in the first aspect, only one magnetic sensor (100) is provided for the coil (301), and is arranged in the center of the coil surface (301a) in a direction parallel to the magnetization direction when viewing the magnetized surface (302a) from the front.

[0147] According to this aspect, it is possible to improve the detection accuracy and further expand the detection area.

[0148] Specifically, by using only one magnetic sensor (100), there is no phase shift (phase shift of the output signal due to mounting errors or individual differences) that tends to occur when using two or more magnetic sensors as in Patent Document 1. This improves the detection accuracy.

[0149] Furthermore, if the position of the magnetic sensor (100) deviates from the center of the coil surface (301a) in the direction parallel to the magnetization direction, a drift of the detection area occurs, and one end of the detection area enters a non-linear region of the output waveform, resulting in a decrease in detection accuracy at that end (in other words, the detection area becomes narrower). In contrast, even if the position of the magnetic sensor (100) deviates from the center of the coil surface (301a) in the direction perpendicular to the magnetization direction, there is little effect on detection accuracy (size of the detection area).

[0150] In other words, the decrease in detection accuracy (reduction in detection area) due to the positional deviation of the magnetic sensor (100) from the center of the coil surface (301a) is significant in the direction parallel to the magnetization direction and is minor in the direction perpendicular to the magnetization direction.

[0151] Therefore, in the present embodiment, by setting the position of the magnetic sensor (100) to the center of the coil surface (301a) with respect to the direction parallel to the magnetization direction, the detection accuracy can be improved as compared with the case where the sensor position is deviated from the center of the coil surface (301a).

[0152] In the motor position detection system (200) according to the third aspect, in the second aspect, the magnetic sensor (100) is arranged at the center of the coil surface (301a) with respect to the direction perpendicular to the magnetization direction when the magnetized surface (302a) is viewed from the front.

[0153] According to this aspect, further improvement in detection accuracy can be achieved.

[0154] In the motor position detection system (200) according to the fourth aspect, in the second aspect, the magnetic sensor (100) is arranged outside the coil surface (301a) with respect to the direction perpendicular to the magnetization direction when the magnetized surface (302a) is viewed from the front.

[0155] According to this aspect, it is possible to improve the degree of freedom in arrangement while maintaining the detection accuracy.

[0156] In the motor position detection system (200) according to the fifth aspect, in the fourth aspect, the magnetic sensor (100) is provided inside the magnetized surface (302a) with respect to the direction perpendicular to the magnetization direction when the magnetized surface (302a) is viewed from the front.

[0157] According to this aspect, since the position of the magnetic sensor (100) is outside the coil surface (301a) and inside the magnetized surface (302a), further improvement in detection accuracy can be achieved.

[0158] In the motor position detection system (200) according to the sixth aspect, in any one of the first to fifth aspects, the processing circuit (201) performs an arctangent operation on the first output signal and the second output signal, and obtains the direction of the magnetic field based on the result of the arctangent operation.

[0159] According to this aspect, the detection area can be further expanded.

[0160] In a motor position detection system (200) according to a seventh aspect, in any one of the first to sixth aspects, the motor (300) further includes a mounting board (303). The mounting board (303) is a board on which the coil (301) is mounted, and has a mounting surface (303a) facing a coil surface (301a) of the coil (301). The magnetic sensor (100) is provided on the mounting board (303) such that the base surface (73a) is perpendicular to the mounting surface (303a).

[0161] According to this embodiment, the magnetic sensor (100) can be fixed at an appropriate position and in an appropriate attitude relative to the coil (301).

[0162] A motor position detection system (200) according to an eighth aspect is any one of the first to seventh aspects, wherein the magnetoresistance effect is a giant magnetoresistance (GMR) effect.

[0163] According to this aspect, it is possible to improve the detection accuracy.

[0164] In a motor position detection system (200) according to a ninth aspect, in any one of the first to seventh aspects, the magnetoresistance effect is a tunnel magnetoresistance (TMR) effect.

[0165] According to this aspect, it is possible to improve the detection accuracy. [Explanation of symbols]

[0166] 1 First half-bridge circuit 1P,1Q First magnetoresistance effect element 1T 1st output terminal 2 Second half-bridge circuit 2P,2Q Second magnetoresistance effect element 2T 2nd output terminal 5 Bias Magnets 73 Base material 73a Base material side 100 Magnetic Sensor 200 Position Sensing System for Motors 201 Processing circuit 300 Motor 301 Coil 301a Coil surface 302 Drive magnet 302a Magnetized surface 303 Mounting Board 303a Mounting surface Mr0 magnetoresistance effect element W1 wiring layer

Claims

1. A motor position detection system for detecting a position of the coil and the drive magnet relative to one of the coil and the drive magnet, the system being used in a motor comprising a coil to which electric power is supplied and a drive magnet that applies a drive magnetic field to the coil, a magnetized surface that is a surface along the magnetization direction of the drive magnet facing a coil surface of the coil, and a drive direction that is a direction of displacement of the other of the coil and the drive magnet relative to one of the coil and the drive magnet being along the magnetization direction, a magnetic sensor that is fixed to the coil and disposed in the vicinity of the coil surface and the magnetized surface, and outputs a signal corresponding to a magnetoresistance effect caused by at least the driving magnetic field from the driving magnet; a processing circuit for processing an output signal of the magnetic sensor; The magnetic sensor includes: A substrate having a substrate surface that is a plane on which an X axis and a Y axis perpendicular to the X axis are defined; a wiring layer disposed along a surface of the substrate and including a first half-bridge circuit and a second half-bridge circuit; a bias magnet that applies a bias magnetic field to the wiring layer; The first half-bridge circuit includes: A pair of first magnetoresistance effect elements connected in a half bridge configuration to detect a magnetic field along the X-axis; a first output terminal that outputs a first output signal from a connection point between the pair of first magnetoresistance effect elements; The second half-bridge circuit includes: A pair of second magnetoresistance effect elements connected in a half bridge configuration to detect a magnetic field along the Y-axis; a second output terminal that outputs a second output signal from a connection point between the pair of second magnetoresistance effect elements; The bias magnet is A bias magnetic field is applied to one of the pair of first magnetoresistance effect elements along a positive direction of the X-axis, and a bias magnetic field is applied to the other of the pair of first magnetoresistance effect elements along a negative direction of the X-axis; A bias magnetic field is applied to one of the pair of second magnetoresistance effect elements along the positive direction of the Y axis, and a bias magnetic field is applied to the other of the pair of second magnetoresistance effect elements along the negative direction of the Y axis; the magnetic sensor is disposed such that the substrate surface is parallel to the magnetization direction and perpendicular to the magnetized surface; the processing circuit detects the position of one of the coil and the drive magnet relative to the other by determining the direction of a magnetic field obtained by superimposing the drive magnetic field applied to the magnetic sensor and the bias magnetic field applied to a wiring layer constituting the magnetic sensor based on at least one of the first output signal and the second output signal. Position sensing system for motors.

2. Only one magnetic sensor is provided for the coil, and is disposed at the center of the coil surface in a direction parallel to the magnetization direction when the magnetized surface is viewed from the front.

2. The position sensing system for a motor according to claim 1.

3. the magnetic sensor is disposed at the center of the coil surface in a direction perpendicular to the magnetization direction when the magnetized surface is viewed from the front; 3. The position sensing system for a motor according to claim 2.

4. the magnetic sensor is disposed outside the coil surface in a direction perpendicular to the magnetization direction when the magnetized surface is viewed from the front.

3. The position sensing system for a motor according to claim 2.

5. the magnetic sensor is provided inside the magnetized surface in a direction perpendicular to the magnetization direction when the magnetized surface is viewed from the front, 5. A position sensing system for a motor according to claim 4.

6. the processing circuit performs an arctangent operation on the first output signal and the second output signal, and determines the direction of the magnetic field based on a result of the arctangent operation. A position detection system for a motor according to any one of claims 1 to 5.

7. the motor further includes a mounting board on which the coil is mounted, the mounting board having a mounting surface facing the coil surface of the coil, The magnetic sensor is provided on the mounting board such that the base surface is perpendicular to the mounting surface. A position detection system for a motor according to any one of claims 1 to 6.

8. The magnetoresistance effect is a giant magnetoresistance effect. A position detection system for a motor according to any one of claims 1 to 7.

9. The magnetoresistance effect is a tunnel magnetoresistance effect. A position detection system for a motor according to any one of claims 1 to 7.

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