Magnetic sensor device, magnetic sensor system, and correction method

Abstract

The invention provides a magnetic sensor device, a magnetic sensor system and a correction method. The magnetic sensor device includes a magnetic sensor, a magnetic field generator, and a processor. The processor is configured to generate a first sensitivity, which is a sensitivity of the magnetic sensor when the intensity of the additional magnetic field is changed within a first range, generate a second sensitivity, which is a sensitivity of the magnetic sensor when the intensity of the additional magnetic field is changed within a second range, and determine the intensity of the additional magnetic field based on the detection signal, the first sensitivity, and the second sensitivity. A detection value having a correspondence relationship with a magnetic field component, which is a component in a predetermined direction of the target magnetic field, is generated.

Description

Technical Field

[0001] The present invention relates to a magnetic sensor device including a magnetic field generator for measuring the sensitivity of a magnetic sensor, a magnetic sensor system including the magnetic sensor device, and a method for correcting a detection signal of the magnetic sensor. Background Art

[0002] In recent years, magnetic sensors that detect external magnetic fields have been used in various applications. In some applications, magnetic sensors that utilize magnetic detection elements are sometimes used. For example, magnetoresistive elements are used as magnetic detection elements.

[0003] Magnetic sensors can sometimes experience an offset in their detection signals due to interference magnetic fields and other factors. Furthermore, the sensitivity of magnetic sensors can vary depending on individual sensor differences and the operating environment. These offsets and sensitivity variations can cause detection errors in magnetic sensors. Therefore, it is desirable to be able to correct for these offsets and sensitivities in magnetic sensors.

[0004] International Publication No. 2014 / 141631 discloses a correction device that corrects geomagnetic data based on a correction coefficient.

[0005] Japanese Patent Application Laid-Open Nos. 2020-060457 and 2020-094883 disclose a magnetic sensor device including a magnetic sensor and a magnetic field generating unit for measuring the main axis sensitivity and other axis sensitivity of the magnetic sensor.

[0006] For example, in a magnetic sensor that generates three detection signals corresponding to three directions, correcting the offsets of the three detection signals may require complex calculations, as disclosed in International Publication No. 2014 / 141631. This may increase the load on the processor. Summary of the Invention

[0007] An object of the present invention is to provide a magnetic sensor device, a magnetic sensor system, and a calibration method capable of reducing detection errors of a magnetic sensor by a simple method.

[0008] A magnetic sensor device according to one embodiment of the present invention includes: a magnetic sensor configured to detect a magnetic field component (a component in a predetermined direction) of an object magnetic field at a reference position and output a detection signal; a magnetic field generator configured to generate an additional magnetic field for measuring the sensitivity of the magnetic sensor in the predetermined direction; and a processor configured to receive an input of the detection signal. The processor is configured to generate a first sensitivity (a sensitivity of the magnetic sensor) when the intensity of the additional magnetic field is varied within a first range, and a second sensitivity (a sensitivity of the magnetic sensor) when the intensity of the additional magnetic field is varied within a second range, and to generate a detection value corresponding to the magnetic field component based on the detection signal, the first sensitivity, and the second sensitivity.

[0009] A magnetic sensor system according to one embodiment of the present invention includes the magnetic sensor device of the present invention and an external processor. The detection signal includes a first signal, a second signal, and a third signal corresponding to components of the target magnetic field at a reference position in three different directions. In an orthogonal coordinate system defined by three axes representing the values ​​of the first to third signals, when the coordinates of a group representing the values ​​of the first to third signals at a certain time are set as measurement points, the external processor generates data for the center coordinates of an imaginary sphere having a spherical surface that approximates the distribution of multiple measurement points at multiple time points. The processor of the magnetic sensor device uses this data to correct the offset of each of the first to third signals.

[0010] One embodiment of the present invention relates to a calibration method for calibrating a detection signal of a magnetic sensor configured to detect a magnetic field component, i.e., a component in a predetermined direction of an object magnetic field, at a reference position. In the calibration method, an additional magnetic field is applied to the magnetic sensor to measure its sensitivity in the predetermined direction. The intensity of the additional magnetic field is varied within a first range to generate a first sensitivity, i.e., a sensitivity of the magnetic sensor. The intensity of the additional magnetic field is varied within a second range to generate a second sensitivity, i.e., a sensitivity of the magnetic sensor. Based on the first and second sensitivities, a first value corresponding to the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor is generated. Based on the detection signal, a second value corresponding to the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor is generated. The detection signal offset is corrected based on the first and second values.

[0011] According to the present invention, the detection error of the magnetic sensor can be reduced by a simple method.

[0012] Other objects, features and advantages of the present invention will become more apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a perspective view showing a magnetic sensor device according to the first embodiment of the present invention.

[0014] Figure 2 This is a functional block diagram showing the configuration of the magnetic sensor device according to the first embodiment of the present invention.

[0015] Figure 3 It is a plan view showing the magnetic sensor device according to the first embodiment of the present invention.

[0016] Figure 4 1 is a circuit diagram showing the circuit configurations of first and second detection circuits in the first embodiment of the present invention.

[0017] Figure 5It is a perspective view showing a part of one resistor portion in the first embodiment of the present invention.

[0018] Figure 6 It is a perspective view showing a magnetoresistive effect element according to the first embodiment of the present invention.

[0019] Figure 7 This is a circuit diagram showing the circuit configuration of the third detection circuit in the first embodiment of the present invention.

[0020] Figure 8 It is a perspective view showing a part of the third detection circuit in the first embodiment of the present invention.

[0021] Figure 9 It is a plan view showing a portion of the third detection circuit in the first embodiment of the present invention.

[0022] Figure 10 It is a side view showing a part of the third detection circuit in the first embodiment of the present invention.

[0023] Figure 11 This is a characteristic diagram showing an example of the relationship between the first magnetic field component and the first detection signal in the first embodiment of the present invention.

[0024] Figure 12 This is a characteristic diagram showing an example of the relationship between the third magnetic field component and the third detection signal in the first embodiment of the present invention.

[0025] Figure 13 This is a characteristic diagram showing an example of the relationship between the third magnetic field component and sensitivity change in the first embodiment of the present invention.

[0026] Figure 14 This is a flowchart showing the calibration method according to the first embodiment of the present invention.

[0027] Figure 15 This is a characteristic diagram showing the linearity of the third detection signal in the first embodiment of the present invention.

[0028] Figure 16 This is a functional block diagram showing the configuration of a magnetic sensor system according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0029] [First embodiment]

[0030] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figures 1 to 3 A magnetic sensor device 100 according to a first embodiment of the present invention will be described. Figure 1 1 is a perspective view showing the magnetic sensor device 100 according to this embodiment. Figure 21 is a functional block diagram showing the configuration of the magnetic sensor device 100 according to this embodiment. Figure 3 1 is a plan view showing the magnetic sensor device 100 according to this embodiment.

[0031] The magnetic sensor device 100 includes a magnetic sensor 1 configured to detect a target magnetic field as a detection target magnetic field and output at least one detection signal; a processor 2 configured to receive at least one detection signal; and a magnetic field generator 70 configured to generate at least one additional magnetic field for measuring the sensitivity of the magnetic sensor 1. The target magnetic field may be the Earth's magnetism, a magnetic field generated by a magnet, or a magnetic field generated by wiring through which current flows. In this embodiment, the target magnetic field is a magnetic field other than the Earth's magnetism. An example in which the target magnetic field is the Earth's magnetism is described in the second embodiment.

[0032] like Figure 1 As shown, the magnetic sensor 1 has the form of a first chip. In addition, the processor 2 has the form of a second chip different from the first chip. The magnetic sensor 1 and the processor 2 both have a rectangular parallelepiped shape. The magnetic sensor 1 has an upper surface 1a and a lower surface 1b located on opposite sides of each other, and four side surfaces connecting the upper surface 1a and the lower surface 1b. The outer surface of the processor 2 includes an upper surface 2a and a lower surface 2b located on opposite sides of each other, and four side surfaces connecting the upper surface 2a and the lower surface 2b. The magnetic sensor 1 can also be mounted on the upper surface 2a with the lower surface 1b facing the upper surface 2a of the processor 2.

[0033] The magnetic sensor 1 has a plurality of electrode pads provided on the upper surface 1a. The processor 2 has a plurality of electrode pads provided on the upper surface 2a. The plurality of electrode pads of the magnetic sensor 1 are connected to the plurality of electrode pads of the processor 2 using, for example, a plurality of bonding wires.

[0034] Here, refer to Figure 1 and Figure 3 The reference coordinate system of this embodiment is described. The reference coordinate system is an orthogonal coordinate system based on the magnetic sensor 1. The X direction, Y direction, and Z direction are defined in the reference coordinate system. Figure 3 As shown, the X direction, Y direction, and Z direction are orthogonal to each other. In addition, the direction opposite to the X direction is referred to as the -X direction, the direction opposite to the Y direction is referred to as the -Y direction, and the direction opposite to the Z direction is referred to as the -Z direction.

[0035] Hereinafter, in the reference coordinate system, a position forward in the Z direction relative to the reference position is referred to as "upper," and a position opposite to "upper" relative to the reference position is referred to as "lower." Furthermore, regarding the components of the magnetic sensor 1, the surface located at one end in the Z direction is referred to as the "upper surface," and the surface located at the end in the -Z direction is referred to as the "lower surface." Furthermore, the expression "when viewed from the Z direction" refers to viewing the object from a position away from the Z direction.

[0036] The magnetic sensor 1 includes a first detection circuit 10 that generates at least one first detection signal, a second detection circuit 20 that generates at least one second detection signal, and a third detection circuit 30 that generates at least one third detection signal. Each of the first to third detection circuits 10, 20, and 30 includes at least one magnetic detection element. In this embodiment, each of the first to third detection circuits 10, 20, and 30 includes a plurality of magnetoresistive elements (hereinafter referred to as MR elements) as at least one magnetic detection element.

[0037] At least one first detection signal, at least one second detection signal, and at least one third detection signal correspond to components in three different directions of the target magnetic field at a reference position (e.g., the position where the magnetic sensor 1 is located). In this embodiment, at least one first detection signal corresponds to a first magnetic field component MFx, which is a component of the target magnetic field parallel to the X direction. At least one second detection signal corresponds to a second magnetic field component MFy, which is a component of the target magnetic field parallel to the Y direction. At least one third detection signal corresponds to a third magnetic field component MFz, which is a component of the target magnetic field parallel to the Z direction.

[0038] The first detection circuit 10 is configured to detect the first magnetic field component MFx and output at least one first detection signal. The second detection circuit 20 is configured to detect the second magnetic field component MFy and output at least one second detection signal. The third detection circuit 30 is configured to detect the third magnetic field component MFz and output at least one third detection signal.

[0039] The magnetic field generator 70 includes a first coil 71 configured to generate a first additional magnetic field, a second coil 72 configured to generate a second additional magnetic field, and a third coil 73 configured to generate a third additional magnetic field. The first additional magnetic field is used to measure the sensitivity of the first detection circuit 10. The second additional magnetic field is used to measure the sensitivity of the second detection circuit 20. The third additional magnetic field is used to measure the sensitivity of the third detection circuit 30. The first through third additional magnetic fields can each be a static magnetic field or an alternating current magnetic field.

[0040] exist Figure 3In the example shown, the first coil 71 is arranged so as to overlap with the first detection circuit 10 when viewed from the Z direction. The second coil 72 is arranged so as to overlap with the second detection circuit 20 when viewed from the Z direction. The third coil 73 is arranged so as to include the third detection circuit 30 inside the third coil 73 when viewed from the Z direction. In addition, as long as the first to third additional magnetic fields can be used to measure the sensitivity of the first to third detection circuits 10, 20, 30, the first to third coils 71 to 73 may also be arranged Figure 3 Locations other than those shown.

[0041] The first to third coils 71 to 73 may be arranged between the upper surface 1a of the magnetic sensor 1 and the lower surface 2b of the processor 2. The first to third coils 71 to 73 may be provided on the magnetic sensor 1 as the first chip or on the processor 2 as the second chip. When the first to third coils 71 to 73 are provided on the processor 2, they may be arranged closer to the upper surface 2a than to the lower surface 2b.

[0042] The processor 2 includes a computing unit 41, a control unit 42, a drive unit 43, and a storage unit 44. The computing unit 41 performs various calculations based on at least one first detection signal, at least one second detection signal, and at least one third detection signal. The drive unit 43 controls the magnetic field generator 70 to generate and vary the first, second, and third additional magnetic fields. The control unit 42 controls the computing unit 41, the drive unit 43, and the storage unit 44. The storage unit 44 may also store various data described below.

[0043] The processor 2 may be formed of, for example, an application-specific integrated circuit (ASIC).

[0044] The magnetic sensor device 100 may include a processor not shown in the figure that is not integrated with the magnetic sensor 1 instead of the processor 2. The processor not shown in the figure may also include the functions of the processor 2. The processor not shown in the figure may be configured by, for example, an ASIC or a microcomputer.

[0045] Next, refer to Figures 4 to 6 The configurations of the first and second detection circuits 10 and 20 will be described. Figure 4 2 is a circuit diagram showing the circuit configuration of the first and second detection circuits 10 and 20 .

[0046] Figure 5 It is a perspective view showing a part of one resistor portion. Figure 6 It is a perspective view showing an MR element.

[0047] like Figure 4As shown, the first detection circuit 10 includes a power supply port V1, a ground port G1, output ports E11 and E12, and resistors R11, R12, R13, and R14. The plurality of MR elements of the first detection circuit 10 constitute resistors R11 to R14.

[0048] Resistor R11 is provided between power port V1 and output port E11. Resistor R12 is provided between output port E11 and ground port G1. Resistor R13 is provided between output port E12 and ground port G1. Resistor R14 is provided between power port V1 and output port E12. A predetermined voltage or current is applied to power port V1. Ground port G1 is grounded.

[0049] The second detection circuit 20 includes a power supply port V2, a ground port G2, output ports E21 and E22, and resistors R21, R22, R23, and R24. The plurality of MR elements of the second detection circuit 20 constitute resistors R21 to R24.

[0050] Resistor R21 is provided between power port V2 and output port E21. Resistor R22 is provided between output port E21 and ground port G2. Resistor R23 is provided between output port E22 and ground port G2. Resistor R24 ​​is provided between power port V2 and output port E22. A predetermined voltage or current is applied to power port V2. Ground port G2 is grounded.

[0051] Here, multiple MR elements are described. The MR element can be a spin valve MR element or an AMR (anisotropic magnetoresistance) element. In this embodiment, the MR element is particularly a spin valve MR element. A spin valve MR element includes a magnetization pinned layer having a fixed magnetization direction, a free layer having a magnetization direction that can change according to the magnetic field applied to the magnetic sensor 1, and a gap layer arranged between the magnetization pinned layer and the free layer. A spin valve MR element can be a TMR (tunnel magnetoresistance) element or a GMR (giant magnetoresistance) element. In a TMR element, the gap layer is a tunnel barrier layer. In a GMR element, the gap layer is a non-magnetic conductive layer. In a spin valve MR element, the resistance value changes depending on the angle between the magnetization direction of the free layer and the magnetization direction of the magnetization pinned layer. When the angle is 0°, the resistance value is minimum, and when the angle is 180°, the resistance value is maximum. The free layer has shape anisotropy such that the easy magnetization axis is perpendicular to the magnetization direction of the fixed magnetization layer. Alternatively, a magnet that applies a bias magnetic field to the free layer can be used as a means for setting the easy magnetization axis in a predetermined direction for the free layer.

[0052] Figure 5A portion of any resistor section among the resistor sections R11 to R14 of the first detection circuit 10 and the resistor sections R21 to R24 of the second detection circuit 20 is shown. Figure 5 This figure shows an example of connecting CPP (Current Perpendicular-to-Plane) type MR elements in series. An arbitrary resistor portion includes a plurality of lower electrodes 61, a plurality of MR elements 50, and a plurality of upper electrodes 62. The plurality of lower electrodes 61 are arranged on a substrate (not shown). Each lower electrode 61 has an elongated shape. A gap is formed between two adjacent lower electrodes 61 in the longitudinal direction of the lower electrodes 61. Figure 5 As shown, MR elements 50 are arranged on the upper surface of the lower electrode 61 near both ends in the longitudinal direction.

[0053] like Figure 6 As shown, the MR element 50 includes an antiferromagnetic layer 51, a magnetization pinned layer 52, a gap layer 53, and a free layer 54, which are stacked in order from the lower electrode 61 side. The antiferromagnetic layer 51 is electrically connected to the lower electrode 61. The antiferromagnetic layer 51 is made of an antiferromagnetic material and generates exchange coupling with the magnetization pinned layer 52, thereby fixing the magnetization direction of the magnetization pinned layer 52.

[0054] like Figure 5 As shown, a plurality of upper electrodes 62 are arranged on a plurality of MR elements 50. Each upper electrode 62 has an elongated shape and electrically connects the free layers 54 of two adjacent MR elements 50 arranged on two adjacent lower electrodes 61 in the longitudinal direction of the lower electrodes 61. With such a structure, Figure 5 The arbitrary resistor portion shown includes a plurality of MR elements 50 connected in series by a plurality of lower electrodes 61 and a plurality of upper electrodes 62 .

[0055] Alternatively, the magnetization pinned layer 52 may be a so-called self-pinned pinned layer (Synthetic FerriPinned layer, SFP layer). A self-pinned pinned layer has a laminated ferrite structure composed of a ferromagnetic layer, a nonmagnetic intermediate layer, and a ferromagnetic layer, and couples the two ferromagnetic layers antiferromagnetically. If the magnetization pinned layer 52 is a self-pinned pinned layer, the antiferromagnetic layer 51 may be omitted.

[0056] In addition, the layers 51 to 54 in the MR element 50 may be arranged in a vertical direction. Figure 6 The configuration shown is the opposite.

[0057] Furthermore, any resistor section may include multiple groups of MR elements 50 connected in parallel. Multiple groups may also be connected in series. Furthermore, the MR element 50 may be a CIP (Current In-Plane) type MR element.

[0058] exist Figure 4 In FIG, each of the resistors R11 to R14 and R21 to R24 is schematically shown as one MR element 50. Figure 4 In FIG, the solid arrow indicates the magnetization direction of the magnetization fixed layer 52 of the MR element 50. Figure 4 In the example shown, the magnetization fixed layer 52 of the MR element 50 in each of the resistor sections R11 and R13 is magnetized in the X direction. The magnetization fixed layer 52 of the MR element 50 in each of the resistor sections R12 and R14 is magnetized in the -X direction.

[0059] The magnetization direction of the magnetization fixed layer 52 of the MR element 50 in each of the resistor sections R21 and R23 is the Y direction. The magnetization direction of the magnetization fixed layer 52 of the MR element 50 in each of the resistor sections R22 and R24 is the -Y direction.

[0060] The potential difference between output port E11 and output port E12 corresponds to the first magnetic field component MFx. The first detection circuit 10 generates a first detection signal S1 corresponding to the potential difference between output port E11 and output port E12. Alternatively, the first detection circuit 10 may generate two signals corresponding to the potentials of output ports E11 and E12, respectively, as two first detection signals, instead of the first detection signal S1.

[0061] The potential difference between output port E21 and output port E22 corresponds to the second magnetic field component MFy. The second detection circuit 20 generates a second detection signal S2 corresponding to the potential difference between output port E21 and output port E22. Alternatively, the second detection circuit 20 may generate two signals corresponding to the potentials of output ports E21 and E22, respectively, as two second detection signals, instead of the second detection signal S2.

[0062] Next, refer to Figures 7 to 10 The configuration of the third detection circuit 30 will be described. Figure 7 3 is a circuit diagram showing the circuit configuration of the third detection circuit 30 . Figure 8 It is a perspective view showing a part of the third detection circuit 30 . Figure 9 It is a plan view showing a portion of the third detection circuit 30 . Figure 10 It is a side view showing a part of the third detection circuit 30 .

[0063] like Figure 7As shown, the third detection circuit 30 includes a power supply port V3, a ground port G3, output ports E31 and E32, and resistors R31, R32, R33, and R34. The plurality of MR elements 50 of the third detection circuit 30 constitute resistors R31 to R34.

[0064] Resistor R31 is provided between power port V3 and output port E31. Resistor R32 is provided between output port E31 and ground port G3. Resistor R33 is provided between output port E32 and ground port G3. Resistor R34 is provided between power port V3 and output port E32. A predetermined voltage or current is applied to power port V3. Ground port G3 is grounded.

[0065] The third detection circuit 30 may also be provided with at least one magnetic yoke made of a soft magnetic material. When viewed from the Z direction, the at least one magnetic yoke has a shape that is longer in the Y direction. In addition, the at least one magnetic yoke may be configured to generate a magnetic field component detected by the plurality of MR elements 50 of the third detection circuit 30 based on the magnetic field applied to the third detection circuit 30. That is, the at least one magnetic yoke may be configured to receive the third magnetic field component MFz and generate an output magnetic field. In this embodiment, in particular, the output magnetic field includes an output magnetic field component in a direction parallel to the X direction, that is, an output magnetic field component that changes according to the third magnetic field component MFz as the above-mentioned magnetic field component.

[0066] like Figures 8 to 10 As shown, in this embodiment, the third detection circuit 30 includes a plurality of magnetic yokes 55 arranged along the X-direction as at least one magnetic yoke. Each of the plurality of magnetic yokes 55 has, for example, a rectangular parallelepiped shape that is elongated in the Y-direction. The plurality of magnetic yokes 55 have the same shape. Each of the plurality of magnetic yokes 55 has a first end face 55a and a second end face 55b located at opposite ends parallel to the X-direction. In each of the plurality of magnetic yokes 55, the first end face 55a is located at one end in the -X-direction, and the second end face 55b is located at one end in the X-direction.

[0067] like Figure 8 and Figure 9 As shown, in the third detection circuit 30, a plurality of MR elements 50 are arranged in a row along the first end surface 55a, and a plurality of MR elements 50 are arranged in a row along the second end surface 55b. Hereinafter, the plurality of MR elements 50 arranged along the first end surface 55a are denoted by reference numeral 50A, and the plurality of MR elements 50 arranged along the second end surface 55b are denoted by reference numeral 50B. In the third detection circuit 30, the plurality of MR elements 50A and the plurality of MR elements 50B are arranged so that the rows of MR elements 50A arranged in a row and the rows of MR elements 50B arranged in a row are alternately arranged in a direction parallel to the X direction. Figure 9 and Figure 10As shown in FIG. 1 , when viewed from the Z direction, the plurality of MR elements 50A and the plurality of MR elements 50B may not overlap with the plurality of magnetic yokes 55. Figure 10 As shown, the plurality of MR elements 50A and the plurality of MR elements 50B may be arranged near the bottom surfaces of the plurality of yokes 55 .

[0068] Although not shown in the figure, the third detection circuit 30 further includes a plurality of first lower electrodes, a plurality of second lower electrodes, a plurality of first upper electrodes, and a plurality of second upper electrodes. Figure 9 In FIG. 1 , reference numeral 80 denotes a wiring portion composed of a plurality of first lower electrodes, a plurality of second lower electrodes, a plurality of first upper electrodes, and a plurality of second upper electrodes. Similar to the plurality of MR elements 50 in the first and second detection circuits 10 and 20 , the plurality of MR elements 50A are connected in series via a plurality of first lower electrodes and a plurality of first upper electrodes. Similar to the plurality of MR elements 50 in the first and second detection circuits 10 and 20 , the plurality of MR elements 50B are connected in series via a plurality of second lower electrodes and a plurality of second upper electrodes.

[0069] Resistor sections R31 and R32 are each composed of a plurality of MR elements 50A. Resistor sections R33 and R34 are each composed of a plurality of MR elements 50B. In both MR elements 50A and 50B, the magnetization direction of the magnetization fixed layer 52 is parallel to the X direction.

[0070] exist Figure 7 In FIG, each of the resistors R31 to R34 is schematically shown as a diagram showing one MR element 50A or 50B. Figure 7 In FIG, the solid arrow indicates the magnetization direction of the magnetization fixed layer 52. Figure 7 In the example shown, the magnetization direction of the magnetization fixed layer 52 in each of the resistor portions R31 and R34 is the X direction. The magnetization direction of the magnetization fixed layer 52 in each of the resistor portions R32 and R33 is the -X direction.

[0071] Next, refer to Figure 7 The at least one third detection signal generated by the third detection circuit 30 is described. Figure 7 In FIG. 1 , as a diagram showing a plurality of yokes 55 corresponding to the plurality of MR elements 50A of the resistor section R31 and the plurality of MR elements 50B of the resistor section R34, one yoke 55 is schematically shown. Figure 7 In FIG. 1 , another yoke 55 is schematically shown as a diagram showing the plurality of yokes 55 corresponding to the plurality of MR elements 50A of the resistor portion R32 and the plurality of MR elements 50B of the resistor portion R33 .

[0072] In the absence of the third magnetic field component MFz, the magnetization direction of the free layer 54 of the MR element 50 becomes parallel to the Y direction, even in the absence of an output magnetic field component parallel to the X direction. In the presence of the third magnetic field component MFz in the Z direction, the output magnetic field component experienced by the MR element 50A in resistors R31 and R32 is oriented in the X direction, while the output magnetic field component experienced by the MR element 50B in resistors R33 and R34 is oriented in the -X direction. In this case, the magnetization direction of the free layer 54 of the MR element 50A in resistors R31 and R32 tilts from parallel to the Y direction toward the X direction, while the magnetization direction of the free layer 54 of the MR element 50B in resistors R33 and R34 tilts from parallel to the Y direction toward the -X direction. As a result, the resistance values ​​of the MR element 50A in resistor R31 and the MR element 50B in resistor R33 and R34 decrease compared to the absence of the output magnetic field component, and the resistance values ​​of the resistors R31 and R33 also decrease. Furthermore, compared to a state in which no output magnetic field component exists, the resistance values ​​of the MR element 50A in the resistor section R32 and the MR element 50B in the resistor section R34 increase, and the resistance values ​​of the resistor sections R32 and R34 also increase.

[0073] When the third magnetic field component MFz in the -Z direction exists, the direction of the output magnetic field component and the change in the resistance value of the resistors R31 to R34 are opposite to those in the case where the third magnetic field component MFz in the Z direction exists.

[0074] The amount of change in the resistance value of MR element 50 depends on the strength of the output magnetic field component applied to MR element 50. As the strength of the output magnetic field component increases, the amount of increase or decrease in the resistance value of MR element 50 increases. As the strength of the output magnetic field component decreases, the amount of increase or decrease in the resistance value of MR element 50 decreases. The strength of the output magnetic field component depends on the strength of the third magnetic field component MFz.

[0075] Thus, when the direction and intensity of the third magnetic field component MFz change, the resistance values ​​of the resistors R31 to R34 change in such a way that as the resistance values ​​of the resistors R31 and R33 increase, the resistance values ​​of the resistors R32 and R34 decrease, or as the resistance values ​​of the resistors R31 and R33 decrease, the resistance values ​​of the resistors R32 and R34 increase. Figure 7 The potential of each of the output ports E31 and E32 shown changes.

[0076] The potential difference between output port E31 and output port E32 corresponds to the third magnetic field component MFz. The third detection circuit 30 generates a third detection signal S3 corresponding to the potential difference between output port E31 and output port E32. Alternatively, the third detection circuit 30 may generate two signals corresponding to the potentials of output ports E31 and E32, respectively, as two third detection signals, instead of the third detection signal S3.

[0077] Next, refer to Figure 2 and Figure 3 The magnetic field generator 70 will be described. As described above, the magnetic field generator 70 includes the first to third coils 71 to 73 .

[0078] The first coil 71 is configured to apply a component of the first additional magnetic field parallel to the X direction to the first detection circuit 10. In the following description, the term "first additional magnetic field" refers to the component of the first additional magnetic field applied to the first detection circuit 10 parallel to the X direction. The driver 43 controls the direction and intensity of the first additional magnetic field by controlling the direction and magnitude of the current flowing through the first coil 71. In this embodiment, the first coil 71 has a first end 71a and a second end 71b that serve as input and output terminals for the current flowing through the first coil 71. The first and second ends 71a and 71b are connected to the driver 43 of the processor 2. When current flows from the first end 71a to the second end 71b, the first additional magnetic field in the X direction is applied to the first detection circuit 10. Furthermore, when current flows from the second end 71b to the first end 71a, the first additional magnetic field in the -X direction is applied to the first detection circuit 10. The storage unit 44 of the processor 2 may also store data indicating the correspondence between the current flowing through the first coil 71 and the first additional magnetic field.

[0079] The second coil 72 is configured to apply a component of the second additional magnetic field parallel to the Y direction to the second detection circuit 20. In the following description, the term "second additional magnetic field" refers to the component of the second additional magnetic field applied to the second detection circuit 20 parallel to the Y direction. The driver 43 controls the direction and intensity of the second additional magnetic field by controlling the direction and magnitude of the current flowing through the second coil 72. In this embodiment, the second coil 72 has a first end 72a and a second end 72b as input and output terminals for the current flowing through the second coil 72. The first and second ends 72a and 72b are connected to the driver 43 of the processor 2. When current flows from the first end 72a to the second end 72b, a second additional magnetic field in the Y direction is applied to the second detection circuit 20. Furthermore, when current flows from the second end 72b to the first end 72a, a second additional magnetic field in the -Y direction is applied to the second detection circuit 20. The storage unit 44 of the processor 2 may also store data indicating the correspondence between the current flowing through the second coil 72 and the second additional magnetic field.

[0080] The third coil 73 is configured to apply a component of the third additional magnetic field parallel to the Z direction to the third detection circuit 30. In the following description, the term "third additional magnetic field" refers to the component of the third additional magnetic field applied to the third detection circuit 30 parallel to the Z direction. The driver 43 controls the direction and intensity of the third additional magnetic field by controlling the direction and magnitude of the current flowing through the third coil 73. In this embodiment, the third coil 73 has a first end 73a and a second end 73b as input and output terminals for the current flowing through the third coil 73. The first and second ends 73a and 73b are connected to the driver 43 of the processor 2. When current flows from the first end 73a to the second end 73b, a third additional magnetic field in the Z direction is applied to the third detection circuit 30. Furthermore, when current flows from the second end 73b to the first end 73a, a third additional magnetic field in the -Z direction is applied to the third detection circuit 30. The storage unit 44 of the processor 2 may also store data indicating the correspondence between the current flowing through the third coil 73 and the third additional magnetic field.

[0081] Next, a description will be given of the processor 2. The processor 2 is configured to execute detection value generation processing, sensitivity correction processing, offset correction processing using an offset value, offset correction processing using an additional magnetic field, and nonlinear correction processing.

[0082] First, the detection value generation process will be described. This process generates three detection values ​​corresponding to the first to third magnetic field components MFx, MFy, and MFz, respectively. The processor 2 receives inputs from the first detection circuit 10, the second detection circuit 20, and the third detection circuit 30. The first to third detection signals S1 to S3 are converted from analog signals to digital signals by analog-to-digital converters (not shown) and then input to the processor 41.

[0083] As described above, the first detection signal S1 corresponds to the first magnetic field component MFx. Figure 11 is a characteristic diagram showing an example of the relationship between the first magnetic field component MFx and the first detection signal S1. Figure 11 In FIG, the horizontal axis represents the intensity of the first magnetic field component MFx, and the vertical axis represents the magnitude of the first detection signal S1. Figure 11 In the following description, the intensity of the magnetic field or magnetic field component is represented by the value of the magnetic flux density corresponding to the intensity of the magnetic field or magnetic field component.

[0084] In addition, Figure 11 In the figure, a positive value indicates the intensity of the first magnetic field component MFx when the intensity of the first magnetic field component MFx is in the X direction, and a negative value indicates the intensity of the first magnetic field component MFx when the intensity of the first magnetic field component MFx is in the -X direction. Figure 11 As shown, the magnitude of the first detection signal S1 varies according to the strength of the first magnetic field component MFx. The calculation unit 41 is configured to generate a first detection value corresponding to the first magnetic field component MFx based on the first detection signal S1 when the first magnetic field component MFx is applied to the first detection circuit 10.

[0085] Here, the definition of the sensitivity of the first detection circuit 10 is explained. The sensitivity of the first detection circuit 10 is the ratio of the change of the first detection signal S1 to the change of the first magnetic field component MFx. The sensitivity of the first detection circuit 10 can be determined based on the following formula: Figure 11 The correspondence between the first magnetic field component MFx and the first detection signal S1 is obtained. The storage unit 44 of the processor 2 may also store data indicating the correspondence between the first magnetic field component MFx and the first detection signal S1, as well as data indicating the sensitivity of the first detection circuit 10. This data may be data acquired before shipment or use of the magnetic sensor device 100, treating the first additional magnetic field as the first magnetic field component MFx. The calculation unit 41 may also generate the first detection value through a calculation including, for example, multiplying the first detection signal S1 by the sensitivity of the first detection circuit 10.

[0086] As described above, the second detection signal S2 corresponds to the second magnetic field component MFy. Although not shown, the relationship between the second magnetic field component MFy and the second detection signal S2 is similar to the relationship between the first magnetic field component MFx and the first detection signal S1. The calculation unit 41 generates a second detection value corresponding to the second magnetic field component MFy based on the second detection signal S2 when the second magnetic field component MFy is applied to the second detection circuit 20.

[0087] Similar to the sensitivity of the first detection circuit 10, the sensitivity of the second detection circuit 20 is the ratio of the change in the second detection signal S2 to the change in the second magnetic field component MFy. The sensitivity of the second detection circuit 20 can be calculated based on the correspondence between the second magnetic field component MFy and the second detection signal S2. The storage unit 44 of the processor 2 may also store data indicating the correspondence between the second magnetic field component MFy and the second detection signal S2, as well as data indicating the sensitivity of the second detection circuit 20. This data may be data acquired before shipment or use of the magnetic sensor device 100, treating the second additional magnetic field as the second magnetic field component MFy. The calculation unit 41 may also generate the second detection value through a calculation including, for example, multiplying the second detection signal S2 by the sensitivity of the second detection circuit 20.

[0088] In addition, as described above, the third detection signal S3 and the third magnetic field component MFz have a corresponding relationship. Figure 12 : is a characteristic diagram showing an example of the relationship between the third magnetic field component MFz and the third detection signal S3. Figure 12 In FIG, the horizontal axis represents the intensity of the third magnetic field component MFz, and the vertical axis represents the magnitude of the third detection signal S3. Figure 12 In the figure, a positive value indicates the intensity of the third magnetic field component MFz when the intensity of the third magnetic field component MFz is in the Z direction, and a negative value indicates the intensity of the third magnetic field component MFz when the intensity of the third magnetic field component MFz is in the -Z direction. Figure 12 As shown, the magnitude of the third detection signal S3 varies according to the strength of the third magnetic field component MFz. The calculation unit 41 generates a third detection value corresponding to the third magnetic field component MFz based on the third detection signal S3 when the target magnetic field is applied to the magnetic sensor 1.

[0089] Similar to the sensitivity of the first detection circuit 10, the sensitivity of the third detection circuit 30 is the ratio of the change in the third detection signal S3 to the change in the third magnetic field component MFz. Figure 12 The corresponding relationship between the third magnetic field component MFz and the third detection signal S3 is obtained. Figure 11 and Figure 12As will be appreciated, in this embodiment, the sensitivity of the third detection circuit 30 is lower than that of the first detection circuit 10. The storage unit 44 of the processor 2 may also store data indicating the correspondence between the third magnetic field component MFz and the third detection signal S3, as well as data indicating the sensitivity of the third detection circuit 30. This data may be data obtained before shipment or use of the magnetic sensor device 100, treating the third additional magnetic field as the third magnetic field component MFz. The calculation unit 41 may also generate the third detection value through, for example, a calculation including multiplying the third detection signal S3 by the sensitivity of the third detection circuit 30.

[0090] The calculation unit 41 is configured to output the generated first to third detection values ​​to the outside of the magnetic sensor device 100 .

[0091] Next, the sensitivity correction process will be described. This process corrects the sensitivity of each of the first to third detection circuits 10, 20, and 30. First, the process of correcting the sensitivity of the first detection circuit 10 will be described. The control unit 42 of the processor 2 controls the first coil 71 of the magnetic field generator 70 using the driver 43 to generate and vary the first additional magnetic field. The control unit 42 generates data correlating the first detection signal S1 and the intensity of the first additional magnetic field, or the intensity of the first magnetic field component MFx, when the first additional magnetic field is varied. The intensity of the first magnetic field component MFx can be determined based on the magnitude of the current flowing through the first coil 71. The control unit 42 then stores this generated data in the memory unit 44 of the processor 2 as data indicating the correspondence between the first magnetic field component MFx and the first detection signal S1. Furthermore, the control unit 42 calculates the sensitivity of the first detection circuit 10 based on the data indicating the correspondence between the first magnetic field component MFx and the first detection signal S1, and updates the sensitivity data of the first detection circuit 10 stored in the memory unit 44.

[0092] Next, the process of correcting the sensitivity of the second detection circuit 20 will be described. The control unit 42 of the processor 2 controls the second coil 72 of the magnetic field generator 70 using the driver 43 to generate and vary the second additional magnetic field. The control unit 42 generates data correlating the second detection signal S2 with the intensity of the second additional magnetic field, i.e., the intensity of the second magnetic field component MFy, when the second additional magnetic field is varied. The intensity of the second magnetic field component MFy can be determined based on the magnitude of the current flowing through the second coil 72. The control unit 42 then stores this generated data in the memory unit 44 of the processor 2 as data indicating the correspondence between the second magnetic field component MFy and the second detection signal S2. Furthermore, the control unit 42 calculates the sensitivity of the second detection circuit 20 based on the data indicating the correspondence between the second magnetic field component MFy and the second detection signal S2, and updates the sensitivity data of the second detection circuit 20 stored in the memory unit 44.

[0093] Next, the process of correcting the sensitivity of the third detection circuit 30 will be described. The control unit 42 of the processor 2 controls the third coil 73 of the magnetic field generator 70 using the driver 43 to generate and change the third additional magnetic field. The control unit 42 generates data that correlates the third detection signal S3 and the intensity of the third additional magnetic field when the third additional magnetic field is changed. The intensity of the third additional magnetic field can be determined based on the magnitude of the current flowing through the third coil 73. The control unit 42 then stores the generated data in the memory unit 44 of the processor 2 as data indicating the correspondence between the third additional magnetic field and the third detection signal S3. Furthermore, the control unit 42 calculates the sensitivity of the third detection circuit 30 based on the data indicating the correspondence between the third additional magnetic field and the third detection signal S3, and updates the sensitivity data of the third detection circuit 30 stored in the memory unit 44.

[0094] Furthermore, when an AC magnetic field is used as the first to third additional magnetic fields, error components having frequencies below the frequency of the AC magnetic field can be removed, thereby more accurately correcting the sensitivity of each of the first to third detection circuits 10 , 20 , and 30 .

[0095] Next, the offset correction process using the offset value will be described. The offset correction process corrects the offsets of each of the first to third detection signals S1 to S3. The storage unit 44 of the processor 2 may be configured to store a first offset value, which is the offset value of the first detection signal S1; a second offset value, which is the offset value of the second detection signal S2; and a third offset value, which is the offset value of the third detection signal S3. The first to third offset values ​​are each updated through the update process described below.

[0096] The control unit 42 of the processor 2 may also control the calculation unit 41 to correct the offsets of the first to third detection signals S1 to S3 using the first to third offset values. The calculation unit 41 corrects the first detection signal S1 by, for example, subtracting the first offset value from the first detection signal S1. Similarly, the calculation unit 41 corrects the second detection signal S2 by, for example, subtracting the second offset value from the second detection signal S2, and corrects the third detection signal S3 by subtracting the third offset value from the third detection signal S3.

[0097] Next, the offset correction process using the additional magnetic field is described. Here, the third detection circuit 30 is used as an example for description. First, the parameters related to the sensitivity of the third detection circuit 30 are described. One of the parameters related to sensitivity is sensitivity change. The sensitivity change is a parameter that represents the sensitivity when the intensity of the third magnetic field component MFz is within a specified range, and the amount of change in sensitivity from the intensity of the third magnetic field component MFz within a reference range. The sensitivity when the intensity of the third magnetic field component MFz is within the reference range may also be, for example, the sensitivity when the intensity of the third magnetic field component MFz is within a range including 0.

[0098] Figure 13 This is a characteristic diagram showing an example of the relationship between the third magnetic field component MFz and sensitivity change. Figure 13 In FIG, the horizontal axis represents the third magnetic field component MFz, and the vertical axis represents the sensitivity change. Figure 13 As shown, the absolute value of the sensitivity change is minimum when the intensity of the third magnetic field component MFz is within a predetermined range including 0. Furthermore, the absolute value of the sensitivity change increases as the intensity of the third magnetic field component MFz becomes less than 0, and increases as the intensity of the third magnetic field component MFz becomes greater than 0. When the sensitivity of the third detection circuit 30 is a positive value, the sensitivity of the third detection circuit 30 is maximum when the intensity of the third magnetic field component MFz is within a predetermined range including 0. Figure 13 The memory unit 44 of the processor 2 may store data indicating the correspondence between the third magnetic field component MFz and the sensitivity of the third detection circuit 30, or may store data indicating the correspondence between the third magnetic field component MFz and the sensitivity of the third detection circuit 30 in addition to or in place of the data. Figure 13 The data showing the correspondence between the third magnetic field component MFz and the sensitivity change may be data acquired before shipment or use of the magnetic sensor device 100 using the third additional magnetic field.

[0099] Processor 2 uses Figure 13 The sensitivity characteristics shown in FIG. 3 are used to correct the offset of the third detection signal S3 using the third additional magnetic field. Figure 14The following outlines a correction method for correcting the offset of the third detection signal S3 using a third additional magnetic field. The following description of the correction method includes the description of the correction method of this embodiment. In the correction method, the control unit 42 of the processor 2 first controls the driver 43 to apply a third additional magnetic field to the third detection circuit 30. The driver 43 is controlled to vary the intensity of the third additional magnetic field within a first range. Simultaneously, the calculation unit 41 is controlled to generate a first sensitivity, i.e., a sensitivity of the third detection circuit 30 within the first range (step S11).

[0100] Next, the control unit 42 controls the driving unit 43 to change the intensity of the third additional magnetic field within the second range, and controls the calculation unit 41 to generate the second sensitivity of the third detection circuit 30 within the second range (step S12 ).

[0101] Next, the control unit 42 controls the calculation unit 41 to generate a first value corresponding to the intensity of the third magnetic field component MFz based on the first sensitivity and the second sensitivity (step S13 ).

[0102] Next, the control unit 42 controls the driving unit 43 to stop applying the third additional magnetic field to the third detection circuit 30 (step S14). Next, the control unit 42 controls the computing unit 41 to generate a second value corresponding to the intensity of the third magnetic field component MFz based on the third detection signal S3 (step S15).

[0103] Next, the control unit 42 controls the calculation unit 41 to correct the offset of the third detection signal S3 based on the first value and the second value (step S16). Step S16 includes a first step in which the control unit 42 controls the calculation unit 41 to generate an offset value; a second step in which the control unit 42 updates the offset value stored in the storage unit 44 based on the generated offset value; and a third step in which the control unit 42 uses the updated offset value to correct the offset of the third detection signal S3.

[0104] The above series of steps are executed by the processor 2. Therefore, the processor 2 can also be called a correction device that performs offset correction processing using an additional magnetic field. In addition, step S15 can also be executed before step S11.

[0105] Furthermore, in the above series of steps, the first step from step S11 to step S16 is also a method for generating the offset value of the third detection signal S3. Furthermore, in the above series of steps, the second step from step S11 to step S16 is also a method for updating the offset value of the third detection signal S3.

[0106] Next, the correction method will be described in more detail by giving specific examples of the first range and the second range. Here, the sensitivity of the third detection circuit 30 is a positive value. In addition, when X is set to an arbitrary positive number, the range of the intensity of the third additional magnetic field is -XmT to 0mT as the first range, and the range of the intensity of the third additional magnetic field is 0mT to XmT as the second range. In addition, from the perspective of improving the accuracy of the judgment, it is preferred that X is smaller. The first sensitivity of the third detection circuit 30 is generated by changing the intensity of the third additional magnetic field in the range of -XmT to 0mT. The second sensitivity of the third detection circuit 30 is generated by changing the intensity of the third additional magnetic field in the range of 0mT to XmT. When the intensity of the third magnetic field component MFz detected by the third detection circuit 30 is a positive value, the first sensitivity is greater than the second sensitivity, and when the intensity of the third magnetic field component MFz detected by the third detection circuit 30 is a negative value, the first sensitivity is less than the second sensitivity. In addition, when the intensity of the third magnetic field component MFz detected by the third detection circuit 30 is 0, the first sensitivity is equal to the second sensitivity. In this way, it is possible to utilize Figure 13 The sensitivity characteristics shown determine the intensity of the third magnetic field component MFz.

[0107] Furthermore, when the sensitivity of the third detection circuit 30 is negative, the first sensitivity is greater than the second sensitivity when the intensity of the third magnetic field component MFz is negative, and when the intensity of the third magnetic field component MFz is positive, the first sensitivity is less than the second sensitivity. Furthermore, similarly to the case where the sensitivity of the third detection circuit 30 is positive, when the intensity of the third magnetic field component MFz is zero, the first sensitivity and the second sensitivity are equal.

[0108] When the first sensitivity is equal to the second sensitivity, the value generated based on the first and second sensitivities, that is, the first value representing the intensity of the third magnetic field component MFz, can also be set to 0. In this case, because the intensity of the third magnetic field component MFz is 0, when there is no offset in the third detection signal S3, the value generated based on the third detection signal S3, that is, the second value representing the intensity of the third magnetic field component MFz, also becomes 0. However, when the third detection signal S3 is offset, the second value becomes a value other than 0 (for example, 1.2 mT). In this case, the size of the third detection signal S3 corresponding to the second value becomes the offset value. The size of the third detection signal S3 corresponding to the second value can be determined, for example, by referring to the data maintained in the storage unit 44, that is, the data representing the corresponding relationship between the third magnetic field component MFz and the third detection signal S3.

[0109] In the above description, the determination of whether the intensity of the third magnetic field component MFz is positive or negative is based on the magnitude relationship between the first sensitivity and the second sensitivity. This determination is actually equivalent to determining whether the direction of the third magnetic field component MFz is the Z direction or the -Z direction.

[0110] The offset correction process using the third additional magnetic field is performed before or during use of the magnetic sensor device 100 .

[0111] The first and second ranges described above are merely examples. The first and second ranges can be modified in various ways as long as the intensity of the third magnetic field component MFz can be determined. For example, the boundary between the first and second ranges may not be zero. Alternatively, the first and second ranges may be discontinuous.

[0112] So far, the offset correction process using the additional magnetic field has been described using the third detection circuit 30 as an example. The above description also applies to the first detection circuit 10 and the second detection circuit 20.

[0113] Next, the nonlinear correction process will be described. Here, the third detection circuit 30 is used as an example for description. First, the definition of the linearity of the third detection signal S3 will be described. The linearity uses a characteristic curve (refer to Figure 12 ), and an approximate straight line of the characteristic curve. In other words, linearity is the value obtained by dividing the residual difference between the value on the approximate straight line and the value on the characteristic curve for each of the multiple intensities of the third magnetic field component MFz by the variable range of the third detection signal S3. It can be said that the smaller the linearity value, the better the linearity.

[0114] Figure 15 is a characteristic diagram showing the linearity of the third detection signal S3. Figure 15 In FIG, the horizontal axis represents the intensity of the third magnetic field component MFz, and the vertical axis represents the linearity of the third detection signal S3. Figure 15 As shown, the absolute value of the linearity increases as the absolute value of the intensity of the third magnetic field component MFz increases. The storage unit 44 of the processor 2 may also store data indicating the correspondence between the intensity of the third magnetic field component MFz and the linearity of the third detection signal S3. This data may be data acquired before shipment or use of the magnetic sensor device 100, with the third additional magnetic field being considered the third magnetic field component MFz.

[0115] The storage unit 44 may further store a correction coefficient for correcting the nonlinearity of the change in the third detection signal S3 with respect to the change in the intensity of the third magnetic field component MFz. Figure 15As shown, because the linearity varies depending on the strength of the third magnetic field component MFz, the correction coefficient also varies depending on the strength of the third magnetic field component MFz. The correction coefficient may also be data acquired before shipment or use of the magnetic sensor device 100, considering the third additional magnetic field as the third magnetic field component MFz.

[0116] The control unit 42 of the processor 2 may control the calculation unit 41 so as to correct the third detection signal using the correction coefficient so that the characteristic curve approaches an approximate straight line.

[0117] So far, the nonlinear correction process has been described by taking the third detection circuit 30 as an example. The above description is also applicable to the first detection circuit 10 and the second detection circuit 20.

[0118] Furthermore, when the target magnetic field is an AC magnetic field, the first to third detection signals S1 to S3 are distorted by the AC magnetic field. However, by performing nonlinear correction processing on the first to third detection signals S1 to S3, the distortion of each of the first to third detection signals S1 to S3 can be corrected. This reduces the detection errors of the first to third detection circuits 10, 20, and 30.

[0119] Next, the functions and effects of the magnetic sensor device 100, magnetic sensor system 200, and calibration method according to this embodiment will be described. In this embodiment, as described above, a first sensitivity (the sensitivity of the third detection circuit 30) is generated when the intensity of the third additional magnetic field is varied within a first range, and a second sensitivity (the sensitivity of the third detection circuit 30) is generated when the intensity of the third additional magnetic field is varied within a second range. Based on the third detection signal S3, the first sensitivity, and the second sensitivity, a third detection value corresponding to the intensity of the third magnetic field component MFz is generated. Specifically, the third detection value is generated using the third detection signal S3 that has been calibrated based on the first sensitivity and the second sensitivity.

[0120] In this embodiment, an offset value is generated based on the first and second sensitivities, and this offset value is used to correct the offset of the third detection signal S3. As described in the second embodiment, the offset of the third detection signal S3 can also be corrected by using the center coordinates of an imaginary sphere. However, improving the calculation accuracy of the center coordinates of the imaginary sphere requires data from a large number of measurement points, which increases the computational load.

[0121] In contrast, this embodiment allows for the correction of the offset in the third detection signal S3 by using a relatively simple method, namely, the use of the first and second sensitivities. Furthermore, obtaining the center coordinates of the imaginary sphere and acquiring multiple measurement points requires a predetermined movement of the magnetic sensor device 100. In contrast, this embodiment eliminates the need for such predetermined movements. Consequently, this embodiment allows for the simple reduction of detection errors in the third detection circuit 30 caused by the offset in the third detection signal S3.

[0122] Furthermore, in this embodiment, the third detection circuit 30 includes multiple magnetic yokes 55. If the multiple magnetic yokes 55 are magnetized in a predetermined direction due to, for example, an interfering magnetic field, the third detection signal S3 may be offset. However, according to this embodiment, as described above, this offset in the third detection signal S3 can be corrected using a simple method.

[0123] Furthermore, when the plurality of magnetic yokes 55 are magnetized in a predetermined direction, there may be variations in the sensitivity of the third detection circuit 30. In contrast, according to this embodiment, the sensitivity of the third detection circuit 30 can be corrected using the third additional magnetic field.

[0124] The above description of the third detection circuit 30 also applies to the first detection circuit 10. In this embodiment, a first sensitivity (the sensitivity of the first detection circuit 10) is generated when the intensity of the first additional magnetic field varies within a first range, and a second sensitivity (the sensitivity of the first detection circuit 10) is generated when the intensity of the first additional magnetic field varies within a second range. Based on the first detection signal S1, the first sensitivity, and the second sensitivity, a first detection value corresponding to the intensity of the first magnetic field component MFx is generated. Specifically, the first detection value is generated using the first detection signal S1 that has been corrected based on the first sensitivity and the second sensitivity. According to this embodiment, the detection error of the first detection circuit 10 caused by the offset of the first detection signal S1 can be reduced through a simple method.

[0125] Furthermore, the above description of the third detection circuit 30 also applies substantially to the second detection circuit 20. In this embodiment, a first sensitivity, which indicates the sensitivity of the second detection circuit 20 when the intensity of the second additional magnetic field varies within a first range, and a second sensitivity, which indicates the sensitivity of the second detection circuit 20 when the intensity of the second additional magnetic field varies within a second range, are generated. Based on the second detection signal S2, the first sensitivity, and the second sensitivity, a second detection value corresponding to the intensity of the second magnetic field component MFy is generated. Specifically, the second detection value is generated using the second detection signal S2 that has been corrected based on the first sensitivity and the second sensitivity. According to this embodiment, the detection error of the second detection circuit 20 caused by the offset of the second detection signal S2 can be reduced using a simple method.

[0126] [Second embodiment]

[0127] Next, the second embodiment of the present invention will be described. Figure 16 The structure of the magnetic sensor system 200 of this embodiment will be briefly described. The magnetic sensor system 200 includes the magnetic sensor device 100 of this embodiment and an external processor 201, which serves as a so-called host processor. The structure of the magnetic sensor device 100 of this embodiment is the same as that of the magnetic sensor device 100 of the first embodiment. In particular, in this embodiment, the target magnetic field of the magnetic sensor 1 of the magnetic sensor device 100 is the Earth's magnetism.

[0128] The hardware constituting the external processor 201 is different from the hardware constituting the processor 2. The external processor 201 is constituted by, for example, a microcomputer.

[0129] Next, the operation of the external processor 201 will be described. The configuration is such that the first to third detection signals S1 to S3 are input from the processor 2 to the external processor 201. Here, in the reference coordinate system described in the first embodiment, the coordinates (S1, S2, S3) of the group representing the values ​​of the first to third detection signals S1 to S3 at a certain timing are set as measurement points. If multiple measurement points at multiple timings are obtained when using the magnetic sensor device 100 and the multiple measurement points are plotted in the reference coordinate system, the distribution of the multiple measurement points can be approximated by a spherical surface. In this embodiment, the spherical surface that approximates the distribution of the multiple measurement points is called an approximate spherical surface. The multiple measurement points are distributed on the approximate spherical surface or near the approximate spherical surface.

[0130] External processor 201 generates the center coordinates and radius of a hypothetical sphere having an approximate spherical surface through calculations using the first to third detection signals S1 to S3. The center coordinates and radius of the hypothetical sphere can be obtained, for example, by using four measurement points and a spherical surface equation to determine an approximate spherical surface containing the four measurement points. Alternatively, the center coordinates and radius of the hypothetical sphere can be obtained by using five or more measurement points, a spherical surface equation, and the least squares method to determine an approximate spherical surface that best approximates the five or more measurement points.

[0131] As described above, the multiple measurement points are distributed on or near a spherical surface. If no offset occurs, the center coordinates of the virtual sphere during use of the magnetic sensor device 100 will be consistent or approximately consistent with the center coordinates of the virtual sphere immediately after the magnetic sensor device 100 begins to be used. However, if the first to third detection signals S1 to S3 are offset due to interference other than geomagnetism, the center coordinates of the virtual sphere will deviate from their initial values ​​(e.g., the center coordinates of the virtual sphere at the time of shipment).

[0132] The processor 2 of the magnetic sensor device 100 uses the data of the center coordinates of the imaginary sphere to correct the offsets of the first to third detection signals S1 to S3 respectively, so that the center coordinates of the imaginary sphere in use are consistent with the initial values ​​of the center coordinates of the imaginary sphere. Here, the center coordinates of the imaginary sphere are expressed as (cx, cy, cz). The offset of the first detection signal S1 can be corrected, for example, by subtracting cx from the first detection signal S1. Similarly, the offset of the second detection signal S2 can be corrected, for example, by subtracting cy from the second detection signal S2. Similarly, the offset of the third detection signal S3 can be corrected, for example, by subtracting cz from the third detection signal S3. The external processor 201 actually calculates the offset caused by interference other than geomagnetism. The offset corrected by the processor 2 can also be caused by interference other than geomagnetism. The offset caused by interference other than geomagnetism includes the offset caused by the interfering magnetic field and the offset caused by the MR element 50.

[0133] In this embodiment, the data of the center coordinates of the virtual sphere generated by the external processor 201 is input to the processor 2. The storage unit 44 of the processor 2 updates the offset values ​​of the first to third detection signals S1 to S3 using the data of the center coordinates of the virtual sphere.

[0134] Next, the operation of processor 2 in this embodiment will be described. As in the first embodiment, processor 2 generates first and second sensitivities using first to third additional magnetic fields, thereby detecting the magnetic field applied to first to third detection circuits 10, 20, and 30. In this case, by comparing the intensities of the components of the magnetic field applied to first to third detection circuits 10, 20, and 30 in a predetermined direction, as detected using the first and second sensitivities, with the intensities of the components of the magnetic field applied to first to third detection circuits 10, 20, and 30 in the predetermined direction, as detected without using the first to third additional magnetic fields, it is possible to detect offsets in first to third detection signals S1 to S3.

[0135] After detecting the offsets of the first to third detection signals S1 to S3 , the processor 2 may output a command signal to the external processor 201 to generate the center coordinates and radius of an imaginary sphere having a substantially spherical surface.

[0136] Next, the operation and effects of the magnetic sensor system 200 of this embodiment will be described. According to this embodiment, the offsets of the first to third detection signals S1 to S3 can be easily detected by the processor 2. Therefore, according to this embodiment, the load on the external processor 201 can be reduced.

[0137] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the magnetic sensor 1 of this embodiment may not include any of the first to third detection circuits 10 , 20 , and 30 .

[0138] In addition, the first coil 71 and the second coil 72 may be arranged so as to overlap with both the first and second detection circuits 10 and 20. In addition, the first to third coils 71 to 73 may be arranged above the magnetic sensor 1.

[0139] Alternatively, the target magnetic field may be an AC magnetic field. In this case, the first to third detection circuits 10, 20, and 30 of the magnetic sensor 1 are connected to the processor 2 using AC coupling capacitors. In this case, by using the AC magnetic field as the additional magnetic field, the processor 2 generates the first and second sensitivities, enabling detection of the static magnetic field applied to the magnetic sensor 1.

[0140] As described above, the magnetic sensor device of the present invention includes: a magnetic sensor configured to detect a magnetic field component, i.e., a component in a predetermined direction of a target magnetic field, and output a detection signal; a magnetic field generator configured to generate an additional magnetic field for measuring the sensitivity of the magnetic sensor in the predetermined direction; and a processor configured to receive an input of the detection signal. The processor is configured to generate a first sensitivity, i.e., the sensitivity of the magnetic sensor when the intensity of the additional magnetic field is varied within a first range, and a second sensitivity, i.e., the sensitivity of the magnetic sensor when the intensity of the additional magnetic field is varied within a second range, and to generate a detection value corresponding to the magnetic field component based on the detection signal, the first sensitivity, and the second sensitivity.

[0141] In the magnetic sensor device of the present invention, the sensitivity of the magnetic sensor may be changed according to the intensity of the component in a predetermined direction of the magnetic field applied to the magnetic sensor.

[0142] In the magnetic sensor device of the present invention, the processor may determine that the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor is zero when the first sensitivity and the second sensitivity are equal.

[0143] In the magnetic sensor device of the present invention, the processor may use the first sensitivity and the second sensitivity to determine whether the direction of the component of the predetermined direction of the magnetic field applied to the magnetic sensor is the first direction or the second direction opposite to the first direction.

[0144] Furthermore, in the magnetic sensor device of the present invention, the processor may be configured to further store data indicating a correspondence relationship between the intensity of a component in a predetermined direction of a magnetic field applied to the magnetic sensor and the sensitivity of the magnetic sensor.

[0145] In the magnetic sensor device of the present invention, the magnetic field generator may include a coil. The strength of the additional magnetic field may vary depending on the magnitude of the current flowing through the coil. The processor may also be configured to store data indicating the correspondence between the magnitude of the current flowing through the coil and the strength of the additional magnetic field.

[0146] Furthermore, in the magnetic sensor device of the present invention, the magnetic field generator may be configured to generate an AC magnetic field as the additional magnetic field.

[0147] Furthermore, in the magnetic sensor device of the present invention, the processor may correct the detection signal based on the first sensitivity and the second sensitivity. The processor may also be configured to further maintain an offset value for the detection signal. The processor may also use the offset value to correct the detection signal. The processor may also generate a first value representing the intensity of a component in a specified direction of the magnetic field applied to the magnetic sensor based on the first sensitivity and the second sensitivity at a specified timing, and generate a second value representing the intensity of a component in a specified direction of the magnetic field applied to the magnetic sensor based on the detection signal at the specified timing, and update the offset value based on the first and second values. The specified timing may be before use of the magnetic sensor device. Alternatively, the specified timing may be during use of the magnetic sensor device.

[0148] Furthermore, in the magnetic sensor device of the present invention, the processor may be configured to further maintain a correction coefficient that corrects the nonlinearity of changes in the detection signal relative to changes in the intensity of the component of the magnetic field applied to the magnetic sensor in a predetermined direction. The processor may also use the correction coefficient to correct the detection signal. The correction coefficient may also vary depending on the intensity of the component of the magnetic field applied to the magnetic sensor in the predetermined direction. The processor may also generate the correction coefficient by varying the intensity of the additional magnetic field.

[0149] In the magnetic sensor device of the present invention, the magnetic sensor may include a magnetic detection element and a yoke made of a soft magnetic material. The yoke may be configured to generate an output magnetic field component detected by the magnetic detection element based on a component in a predetermined direction of a magnetic field applied to the magnetic sensor.

[0150] Furthermore, in the magnetic sensor device of the present invention, the magnetic sensor may include a magnetoresistive effect element.

[0151] In the magnetic sensor device of the present invention, the magnetic sensor and the processor may each have an upper surface and a lower surface facing opposite sides. The magnetic sensor may be mounted on the processor with the lower surface of the magnetic sensor facing the upper surface of the processor. The magnetic field generator may include a coil. The coil may be positioned between the upper surface of the magnetic sensor and the lower surface of the processor.

[0152] The magnetic sensor system of the present invention includes the magnetic sensor device of the present invention and an external processor. The detection signal includes a first signal, a second signal, and a third signal that correspond to components of the target magnetic field at a reference position in three different directions. In an orthogonal coordinate system defined by three axes representing the values ​​of the first to third signals, when the coordinates of a group representing the values ​​of the first to third signals at a certain time are set as measurement points, the external processor generates data for the center coordinates of an imaginary sphere having a spherical surface that approximates the distribution of multiple measurement points at multiple time points. The processor of the magnetic sensor device uses this data to correct the offset of each of the first to third signals.

[0153] In the magnetic sensor system of the present invention, the offset corrected by the processor of the magnetic sensor device may also be caused by disturbances other than the Earth's magnetism.

[0154] The calibration method of the present invention is a method for calibrating a detection signal of a magnetic sensor configured to detect a component in a predetermined direction of a target magnetic field, i.e., a magnetic field component. In the calibration method of the present invention, an additional magnetic field is applied to the magnetic sensor to measure its sensitivity in the predetermined direction. The intensity of the additional magnetic field is varied within a first range to generate a first sensitivity of the magnetic sensor. The intensity of the additional magnetic field is varied within a second range to generate a second sensitivity of the magnetic sensor. Based on the first sensitivity and the second sensitivity, a first value corresponding to the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor is generated. A second value corresponding to the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor is generated based on the detection signal. The offset of the detection signal is corrected based on the first and second values.

[0155] In the magnetic sensor device and magnetic sensor system of the present invention, a first sensitivity (the sensitivity of the magnetic sensor when the intensity of the applied magnetic field is varied within a first range) and a second sensitivity (the sensitivity of the magnetic sensor when the intensity of the applied magnetic field is varied within a second range) are generated. A detection value corresponding to the magnetic field component is generated based on a detection signal, the first sensitivity, and the second sensitivity. In the correction method of the present invention, a first value corresponding to the intensity of the component in a predetermined direction of the magnetic field applied to the magnetic sensor is generated based on the first sensitivity and the second sensitivity, a second value corresponding to the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor is generated based on the detection signal, and the offset of the detection signal is corrected based on the first and second values.

[0156] As will be apparent from the above description, the present invention can be implemented in various forms and variations. Therefore, within the scope of the claims and equivalents, the present invention can be implemented in forms other than the best form described above.

Claims

1. A magnetic sensor device, characterized in that have: a magnetic sensor configured to detect a magnetic field component in a predetermined direction as a component of a target magnetic field and output a detection signal; a magnetic field generator configured to generate an additional magnetic field for measuring the sensitivity of the magnetic sensor in the predetermined direction; as well as a processor configured to receive the detection signal as input, The processor is configured as follows: generating a first sensitivity, the first sensitivity being the sensitivity of the magnetic sensor when the intensity of the additional magnetic field is varied within a first range; generating a second sensitivity, the second sensitivity being the sensitivity of the magnetic sensor when the intensity of the additional magnetic field is varied within a second range; A detection value corresponding to the magnetic field component is generated based on the detection signal, the first sensitivity, and the second sensitivity.

2. The magnetic sensor device according to claim 1, wherein The sensitivity of the magnetic sensor changes according to the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor.

3. The magnetic sensor device according to claim 1, wherein The processor determines that the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor is zero when the first sensitivity and the second sensitivity are equal.

4. The magnetic sensor device according to claim 1, wherein The processor determines whether the direction of the predetermined-direction component of the magnetic field applied to the magnetic sensor is a first direction or a second direction opposite to the first direction, using the first sensitivity and the second sensitivity.

5. The magnetic sensor device according to claim 1, wherein The processor is further configured to store data indicating a correspondence between the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor and the sensitivity of the magnetic sensor.

6. The magnetic sensor device according to claim 1, wherein The magnetic field generator comprises a coil, The strength of the additional magnetic field varies depending on the magnitude of the current flowing through the coil.

7. The magnetic sensor device according to claim 6, wherein The processor is further configured to store data indicating a correspondence between the magnitude of the current flowing through the coil and the intensity of the additional magnetic field.

8. The magnetic sensor device according to claim 1, wherein The magnetic field generator is configured to generate an alternating current magnetic field as the additional magnetic field.

9. The magnetic sensor device according to claim 1, wherein The processor corrects the detection signal based on the first sensitivity and the second sensitivity.

10. The magnetic sensor device according to claim 9, wherein The processor is further configured to maintain an offset value of the detection signal, The processor corrects the detection signal using the offset value.

11. The magnetic sensor device according to claim 10, wherein The processor generates a first value representing the intensity of the component in the specified direction of the magnetic field applied to the magnetic sensor based on the first sensitivity and the second sensitivity at the specified timing, generates a second value representing the intensity of the component in the specified direction of the magnetic field applied to the magnetic sensor based on the detection signal at the specified timing, and updates the offset value based on the first value and the second value.

12. The magnetic sensor device according to claim 11, wherein The predetermined timing is before use of the magnetic sensor device.

13. The magnetic sensor device according to claim 11, wherein The predetermined timing is when the magnetic sensor device is in use.

14. The magnetic sensor device according to claim 1, wherein The processor is further configured to hold a correction coefficient for correcting nonlinearity of a change in the detection signal with respect to a change in the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor. The processor corrects the detection signal using the correction coefficient.

15. The magnetic sensor device according to claim 14, wherein The correction coefficient changes according to the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor. The processor varies the intensity of the additional magnetic field to generate the correction coefficient.

16. The magnetic sensor device according to claim 1, wherein The magnetic sensor includes a magnetic detection element and a yoke made of a soft magnetic body. The yoke is configured to generate an output magnetic field component detected by the magnetic detection element based on the component in the predetermined direction of the magnetic field applied to the magnetic sensor.

17. The magnetic sensor device according to claim 1, wherein The magnetic sensor includes a magnetoresistive effect element.

18. The magnetic sensor device according to claim 1, wherein The magnetic sensor and the processor respectively have an upper surface and a lower surface facing opposite sides to each other, The magnetic sensor is mounted on the processor in a posture where the lower surface of the magnetic sensor faces the upper surface of the processor. The magnetic field generator comprises a coil, The coil is disposed between the upper surface of the magnetic sensor and the lower surface of the processor.

19. A magnetic sensor system, characterized in that: have: The magnetic sensor device according to claim 1; and External processor, The detection signal includes a first signal, a second signal, and a third signal corresponding to components of the target magnetic field in three different directions at a reference position. In an orthogonal coordinate system defined by three axes for representing the values ​​of the first to third signals, when coordinates of a group representing the values ​​of the first to third signals at a certain timing are set as measurement points, the external processor generates data having center coordinates of a virtual sphere having a spherical surface that approximates the distribution of the plurality of measurement points at the plurality of timings. The processor of the magnetic sensor device corrects offsets of each of the first to third signals using the data of the center coordinates.

20. The magnetic sensor system according to claim 19, wherein The offset corrected by the processor of the magnetic sensor device is caused by interference other than geomagnetism.

21. A calibration method, characterized in that: The correction method corrects a detection signal of a magnetic sensor configured to detect a magnetic field component as a component of a target magnetic field in a predetermined direction. In the correction method, applying an additional magnetic field for measuring the sensitivity of the magnetic sensor in the predetermined direction to the magnetic sensor, and varying the intensity of the additional magnetic field within a first range to generate a first sensitivity as the sensitivity of the magnetic sensor; while varying the intensity of the additional magnetic field within a second range and generating a second sensitivity as the sensitivity of the magnetic sensor, generating a first value corresponding to the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor based on the first sensitivity and the second sensitivity; generating a second value corresponding to the intensity of the component in the predetermined direction of the magnetic field applied to the magnetic sensor based on the detection signal; An offset of the detection signal is corrected based on the first value and the second value.

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