Magnetic sensor

Abstract

To provide a magnetic sensor having good linearity in an output signal regardless of a direction of an external magnetic field to be applied, an electric control device using the same, a method for correcting the output signal of the magnetic sensor, and a method for manufacturing the magnetic sensor.SOLUTION: A signal correction section calculates inverse distortion capable of reducing, to half as a correction value, a maximum value of a distortion error included in a signal output from a magnetic detection section by applying, to a magnetoresistive effect element, a magnetic field from a first intersection direction in which the distortion error included in the signal output from the magnetic detection section indicates a maximum value by adding, to the magnetoresistive effect element, a magnetic field in an intersection direction which obliquely intersects a sensitivity axis and is a direction different from the sensitivity axis, and generates a corrected signal by correcting the signal by adding, to the signal output from the magnetic detection section, the correction value of inverse distortion, in common to all intersection directions which include both a second intersection in which the distortion error included in the signal output from the magnetic detection section indicates a minimum value and the first intersection direction, and in which the magnetic field intersects at an angle of more than 0° and less than 90° with respect to a direction of the sensitivity axis.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a magnetic sensor, an electric control device using the same, a method for correcting an output signal of the magnetic sensor, and a method for manufacturing the magnetic sensor. [Background technology]

[0002] In recent years, position detection devices for detecting the position, amount of movement (amount of change), orientation, etc., of a moving object due to linear movement have been used in various applications. A known position detection device is one that includes a magnetic sensor unit that outputs a signal in response to an applied magnetic field. An example of the magnetic sensor unit is a laminate having a free layer and a magnetization fixed layer, and includes a magnetoresistance effect element (MR element) whose resistance changes with the change in the direction of the magnetization easy axis of the free layer in response to an external magnetic field.

[0003] The magnetoresistance effect element of the magnetic sensor unit has a sensitivity axis parallel to the magnetization direction of the magnetization fixed layer, and when an external magnetic field in a direction along the sensitivity axis is applied to the magnetoresistance effect element, a signal corresponding to the magnetic field strength of the external magnetic field is output. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-117184 A Summary of the Invention [Problem to be solved by the invention]

[0005] Depending on the environment in which the position detection device is used, an external magnetic field that is inclined and intersects with the sensitivity axis (hereinafter, sometimes referred to as an "oblique magnetic field") may be applied to the magnetoresistance effect element. In this case, distortion due to higher-order harmonic components such as third-order harmonic components contained in the signal output from the magnetic sensor unit becomes large. This causes a problem in that the linearity of the output signal from the magnetic sensor unit deteriorates when an oblique magnetic field is applied to the magnetoresistance effect element.

[0006] In view of the above problems, the present invention aims to provide a magnetic sensor having good linearity in its output signal regardless of the direction of an applied external magnetic field, an electrical control device using the same, a method for correcting the output signal of the magnetic sensor, and a method for manufacturing the magnetic sensor. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a magnetic sensor comprising a magnetic detection unit that outputs a signal upon application of a magnetic field, and a signal correction unit that corrects the signal output from the magnetic detection unit, wherein the magnetic detection unit includes a magnetoresistive effect element having a predetermined sensitivity axis, and the signal correction unit corrects the signal using a correction value that can reduce distortion error contained in the signal output from the magnetic detection unit when the magnetic field in a cross direction that is inclined and intersects with the sensitivity axis is applied to the magnetoresistive effect element, thereby generating a correction signal.

[0008] In the magnetic sensor, the magnetic detection unit may include the magnetoresistance effect element having the sensitivity axis on a first axis. The magnetoresistance effect element may include a first magnetoresistance effect element and a second magnetoresistance effect element, the sensitivity axis of the first magnetoresistance effect element is parallel to the first axis, the sensitivity axis of the second magnetoresistance effect element is parallel to the second axis, the first axis and the second axis are orthogonal to each other, and the intersecting direction may be a direction that intersects both the first axis and the second axis at an angle.

[0009] In the magnetic sensor, the signal correction unit may add an inverse distortion of the distortion error as the correction value to the signal, or may correct the signal by the following formula (1) to generate the corrected signal. V'=V+V 3 ×a ···(1) In the formula (1), V represents "the signal output from the magnetic detection unit", V' represents "the correction signal", and a represents "the correction coefficient".

[0010] The present invention provides an electric control device comprising the above-mentioned magnetic sensor. The present invention provides a method for correcting a signal output from a magnetic detection unit in a magnetic sensor including a magnetoresistive element having a predetermined sensitivity axis and a magnetic detection unit that outputs a signal when a magnetic field is applied to the magnetoresistive element, the correction method comprising the steps of: acquiring the signal output from the magnetic detection unit; and correcting the signal acquired in the step so as to reduce distortion error contained in the signal when the magnetic field in a direction intersecting the sensitivity axis is applied to the magnetoresistive element.

[0011] The present invention provides a method for manufacturing a magnetic sensor including a magnetoresistive element having a predetermined sensitivity axis, a magnetic detection unit that outputs a signal when a magnetic field is applied to the magnetoresistive element, and a signal correction unit that corrects the signal output from the magnetic detection unit, the method comprising the steps of: applying a test magnetic field to the magnetic detection unit in a direction intersecting the sensitivity axis of the magnetoresistive element; and determining a correction value capable of reducing distortion error included in the test signal based on the test signal output from the magnetic detection unit in response to the application of the test magnetic field. Effect of the Invention

[0012] According to the present invention, it is possible to provide a magnetic sensor having excellent linearity in its output signal regardless of the direction of an applied external magnetic field, an electrical control device using the same, a method for correcting the output signal of the magnetic sensor, and a method for manufacturing the magnetic sensor. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a magnetic sensor according to an embodiment of the present invention. [Figure 2A] FIG. 2A is a circuit diagram showing a schematic configuration of a magnetic detection unit in one embodiment of the present invention. [Figure 2B] FIG. 2B is a circuit diagram showing a schematic configuration of another aspect of the magnetic detection unit in one embodiment of the present invention. [Diagram 3] FIG. 3 is a perspective view showing a schematic configuration of a magnetoresistance effect element in one embodiment of the present invention. [Figure 4] FIG. 4 is a block diagram showing a schematic configuration of another aspect of the magnetic sensor according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a graph showing the results of Test Example 1. [Figure 6] FIG. 6 is a graph showing the results of Test Example 2. [Figure 7] FIG. 7 is a graph showing the results of Test Example 3. [Figure 8] FIG. 8 is a graph showing the results of Test Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A magnetic sensor according to an embodiment of the present invention will be described with reference to the drawings. Note that in this embodiment, a current sensor will be described as an example of the magnetic sensor, but the magnetic sensor according to the embodiment is not limited to a current sensor.

[0015] In describing this embodiment, "first axis and second axis" are defined in some drawings as necessary. Here, the first axis is parallel to the sensitivity axis of the magnetoresistance effect element. The second axis is perpendicular to the first axis. In this specification and drawings, the first axis may be referred to as the "X axis" and the second axis may be referred to as the "Y axis". In this specification, "orthogonal" refers to two target lines, axes, directions, etc. intersecting at a perfect 90°, as well as being nearly perpendicular, i.e., intersecting at a slight deviation from 90° (intersection angle within 90°±5°), and "parallel" refers to two target lines, axes, directions, etc. intersecting at a perfect parallel state, as well as being nearly parallel (intersection angle within 5° or less).

[0016] 1, the magnetic sensor 1 according to this embodiment includes a magnetic detection unit 2 that outputs a signal S when a magnetic field is applied, and a signal processing unit 3 that processes the signal S output from the magnetic detection unit 2. The magnetic sensor 1 according to this embodiment may be one in which the magnetic detection unit 2 and the signal processing unit 3 are integrally (monolithically) formed into a one-chip, or one in which the magnetic detection unit 2 and the signal processing unit 3 are resin-sealed into a one-chip, or one in which the magnetic detection unit 2 and the signal processing unit 3 are separately and independently resin-sealed.

[0017] As shown in FIG. 2A and FIG. 2B, the magnetic detection unit 2 may include, for example, a plurality of element units 20 (for example, first to fourth element units 21 to 24), but may include one element unit 20. When a plurality of element units 20 are included, the magnetic detection unit 2 may be configured with a Wheatstone bridge circuit C including the plurality of element units 20 (a full bridge circuit including the first to fourth element units 21 to 24 (see FIG. 2A) or a half bridge circuit including the first element unit 21 and the second element unit 22 (see FIG. 2B)). The Wheatstone bridge circuit C shown in FIG. 2A includes a power supply port V, a ground port G, two output ports E1 and E2, and the first to fourth element units 21 to 24. One end of each of the first element unit 21 and the fourth element unit 24 is connected to the power supply port V. The other end of the first element unit 21 is connected to one end of the second element unit 22 and the output port E1. The other end of fourth element portion 24 is connected to one end of third element portion 23 and output port E2. The other ends of second element portion 22 and third element portion 23 are connected to ground port G. A power supply voltage of a predetermined magnitude is applied to power supply port V, and ground port G is connected to ground.

[0018] In this embodiment, as shown in Fig. 3, the element unit 20 includes a plurality of magnetoresistance effect elements 40 connected in series. Each of the plurality of magnetoresistance effect elements 40 is, for example, a spin-valve type magnetoresistance effect element. In this embodiment, the element unit 20 has a plurality of magnetoresistance effect elements 40 each having a substantially oval shape in a plan view, which are connected via a first lead electrode 51 and a second lead electrode 52 (see Fig. 3).

[0019] The spin-valve magnetoresistance effect element 40 includes an antiferromagnetic layer 41, a magnetization fixed layer 42, a nonmagnetic layer 43, and a free layer 44, which are stacked in this order from the substrate side (not shown). In the embodiment shown in FIG. 3, the free layer 44 is electrically connected to a first lead electrode 51, and the antiferromagnetic layer 41 is electrically connected to a second lead electrode 52. The antiferromagnetic layer 41 is made of an antiferromagnetic material, and plays a role in fixing the direction of magnetization of the magnetization fixed layer 42 by generating exchange coupling between the antiferromagnetic layer 41 and the magnetization fixed layer 42. The magnetoresistance effect element 40 may have a configuration in which the free layer 44, the nonmagnetic layer 43, the magnetization fixed layer 42, and the antiferromagnetic layer 41 are stacked in this order from the substrate side. The antiferromagnetic layer 41 may be omitted by forming the magnetization pinned layer 42 as a so-called self-pinned pinned layer (Synthetic Ferri Pinned Layer, SFP layer) having a laminated ferri structure of ferromagnetic layer / non-magnetic intermediate layer / ferromagnetic layer, and antiferromagnetically coupling both ferromagnetic layers. In the embodiment shown in FIG. 3, the magnetoresistance effect element 40 may include a cap layer located between the free layer 44 and the first lead electrode 51, or may include an underlayer located between the antiferromagnetic layer 41 and the second lead electrode 52. The spin-valve type magnetoresistance effect element 40 may be a TMR element or a GMR element. In the TMR element, the nonmagnetic layer 43 is a tunnel barrier layer. In the GMR element, the nonmagnetic layer 43 is a nonmagnetic conductive layer. In the spin-valve magnetoresistance effect element 40, the resistance value changes depending on the angle that the magnetization direction of the free layer 44 makes with respect to the magnetization direction of the magnetization fixed layer 42, and when this angle is 0°, the resistance value is at its minimum and when it is 180°, the resistance value is at its maximum.

[0020] In this embodiment, the magnetization direction of the magnetization fixed layer 42 of the magnetoresistance effect element 40 is fixed in a direction parallel to the X-axis. In the embodiment shown in FIG. 2A, the magnetization direction of the magnetization fixed layer 42 of the magnetoresistance effect element 40 of the first element unit 21 and the third element unit 23 is the "+X direction", and the magnetization direction of the magnetization fixed layer 42 of the magnetoresistance effect element 40 of the second element unit 22 and the fourth element unit 24 is the "-X direction". In FIG. 2A, the magnetization directions of the magnetization fixed layer 42 of the magnetoresistance effect element 40 of the first to fourth element units 21 to 24 are indicated by arrows. The magnetization direction of the magnetization fixed layer 42 of the magnetoresistance effect element 40 of the first to fourth element units 21 to 24 is parallel to the minor axis direction or the short side direction of the magnetoresistance effect element 40 having a substantially oval or rectangular shape in a plan view. That is, the sensitivity axes of the magnetoresistance effect elements 40 of the first to fourth element portions 21 to 24 are parallel to the X-axis.

[0021] In this embodiment, the magnetization direction of the free layer 44 of the magnetoresistance effect element 40 in the initial state (a state in which a magnetic field to be detected in the magnetic detection unit 2 is not applied) is parallel to the Y axis. In the embodiment shown in FIG. 2A, the magnetization easy axis direction of the free layer 44 of the magnetoresistance effect element 40 of the first element unit 21 and the fourth element unit 24 is the "-Y direction", and the magnetization easy axis direction of the free layer 44 of the magnetoresistance effect element 40 of the second element unit 22 and the third element unit 23 is the "+Y direction". In this embodiment, the magnetization easy axis direction of the free layer 44 of the magnetoresistance effect element 40 of the first to fourth element units 21 to 24 is parallel to the major axis direction of the magnetoresistance effect element 40 having a substantially oval shape in a plan view. Note that the magnetization easy axis directions of the free layer 44 of the magnetoresistance effect element 40 of the first to fourth element units 21 to 24 may all be the "+Y direction" or the "-Y direction". If the shape of the magnetoresistance effect element 40 in a planar view is a shape that is elongated in a direction parallel to the Y direction in a planar view, for example, an approximately oval shape or an approximately rectangular shape, the easy axis direction of magnetization of the free layer 44 is likely to be the "+Y direction" or the "-Y direction" due to shape magnetic anisotropy. However, instead of or in addition to shape magnetic anisotropy, a bias magnetic field generating unit such as a hard magnet (not shown) may be provided to apply a bias magnetic field to the free layer 44, so that the easy axis direction of magnetization of the free layer 44 is the "+Y direction" or the "-Y direction".

[0022] In the magnetic detection unit 2, the potential difference between the output ports E1 and E2 changes as a magnetic field is applied to each of the magnetoresistance effect elements 40 of the first to fourth element units 21 to 24, and a differential detector (not shown) outputs a signal S corresponding to the potential difference between the output ports E1 and E2 to the signal processing unit 3 as a signal representing the magnetic field strength.

[0023] The signal processing unit 3 may include an A / D (analog-to-digital) conversion unit 31 that converts the analog signal output from the magnetic detection unit 2 into a digital signal, and a calculation unit 32 that performs calculations on the digital signal converted by the A / D conversion unit 31.

[0024] The signal S (analog signal) output from the magnetic detection unit 2 is converted into a digital signal by the A / D conversion unit 31, and the digital signal is input to the calculation unit 32. The calculation unit 32 performs a correction process to correct the digital signal converted from the analog signal by the A / D conversion unit 31 to generate a correction signal, and performs calculation processing based on the correction signal. The calculation unit 32 is composed of, for example, a microcomputer, an ASIC (Application Specific Integrated Circuit), etc. In this embodiment, the calculation unit 32 or the signal processing unit 3 including the calculation unit 32 constitutes the signal correction unit.

[0025] In the magnetic sensor 1 having the above configuration, when a magnetic field parallel to the sensitivity axis (X-axis) of the magnetoresistance effect element 40 of the magnetic detection unit 2 is applied to the magnetoresistance effect element 40, the signal S output from the magnetic detection unit 2 does not substantially contain a distortion error due to a higher harmonic component such as a third harmonic component. Note that "substantially does not contain a distortion error" means that even if the signal S contains a distortion error, the distortion error is allowed to be included to an extent that does not cause an error in the physical quantity, orientation, etc. obtained based on the signal S. On the other hand, when a magnetic field (oblique magnetic field) that is inclined and intersects with the sensitivity axis (X-axis) of the magnetoresistance effect element 40 (intersects with the X-axis at an angle greater than 0° and less than 90°) and is parallel to the XY plane is applied, the signal S output from the magnetic detection unit 2 contains a distortion error due to a higher harmonic component such as a third harmonic component. The distortion error included in this signal S is a distortion error that causes an unacceptable error in the physical quantity, orientation, etc. obtained based on the signal S. The magnitude of the distortion error contained in the signal S depends on the intersection angle of the oblique magnetic field with the sensitivity axis (X-axis). Therefore, when the oblique magnetic field is applied to the magnetoresistance effect element 40, the output signal from the magnetic sensor 1 changes depending on the angle of the oblique magnetic field with the sensitivity axis (X-axis), and the linearity of the output signal from the magnetic sensor 1 may deteriorate.

[0026] In the magnetic sensor 1 according to this embodiment, even when the above-mentioned oblique magnetic field is applied to the magnetoresistance effect element 40, the signal S output from the magnetic detection unit 2 is corrected by the calculation unit 32 of the signal processing unit 3, and a corrected signal S' is output. Therefore, the linearity of the output signal from the magnetic sensor 1 can be improved.

[0027] The signal correction process in the calculation unit 32 will now be described. The calculation unit 32 corrects the signal S output from the magnetic detection unit 2 using a predetermined correction value, and generates a corrected signal S'.

[0028] The correction value is a correction value capable of reducing distortion error included in the signal S when a magnetic field (oblique magnetic field) that is parallel to the XY plane and obliquely intersects with the sensitivity axis (X-axis) of the magnetoresistance effect element 40 (intersects with the X-axis at an angle greater than 0° and less than 90°) is applied to the magnetoresistance effect element 40. Specifically, the calculation unit 32 may generate the correction signal S' by correcting the signal S using, for example, the following formula (1). V'=V+V 3 ×a ···(1) In the above formula (1), V represents "signal S output from magnetic detection unit 2," V' represents "correction signal S'," and a represents "correction coefficient (correction value)."

[0029] When the oblique magnetic field intersects the sensitivity axis (X-axis) of the magnetoresistance effect element 40 at 45°, the distortion error included in the signal S output from the magnetic detection unit 2 is at a maximum value. Therefore, in the above formula (1), it is preferable to set "a" representing the correction coefficient as a value capable of reducing by half the distortion error included in the signal S when an oblique magnetic field intersecting the sensitivity axis (X-axis) of the magnetoresistance effect element 40 at 45° is applied to the magnetoresistance effect element 40. In other words, the signal S is corrected by adding an inverse distortion due to the third harmonic component so that the distortion error included in the signal S when a magnetic field parallel to the sensitivity axis (X-axis) is applied to the magnetoresistance effect element 40 and the distortion error included in the signal S when a magnetic field intersecting the sensitivity axis (X-axis) at 45° is applied to the magnetoresistance effect element 40 are the same as the distortion error included in the signal S when a magnetic field parallel to the sensitivity axis (X-axis) is applied to the magnetoresistance effect element 40, and a correction signal S' is generated. By setting a correction coefficient (correction value) capable of reducing by half the distortion error contained in the signal S when a diagonal magnetic field intersecting at 45° is applied to the magnetoresistance effect element 40, and generating the correction signal S' by the above formula (1), it is possible to stabilize the distortion error contained in the signal S regardless of the angle at which the magnetic field applied to the magnetoresistance effect element 40 intersects with the sensitivity axis (X-axis) of the magnetoresistance effect element 40. Therefore, it is possible to improve the linearity of the output signal from the magnetic sensor 1 regardless of the angle of the magnetic field applied to the magnetoresistance effect element 40 with respect to the sensitivity axis (X-axis). When correcting the signal S by adding the inverse distortion due to the third harmonic component, it is desirable to make the distortion error contained in the signal S when a magnetic field parallel to the sensitivity axis (X-axis) is applied to the magnetoresistance effect element 40 identical to the distortion error contained in the signal S when a magnetic field intersecting the sensitivity axis (X-axis) at 45° is applied to the magnetoresistance effect element 40; however, the signal S may be corrected by adding the inverse distortion due to the third harmonic component so as to reduce the distortion error contained in the signal S at least when a magnetic field intersecting the sensitivity axis (X-axis) at 45° is applied to the magnetoresistance effect element 40.

[0030] As shown in FIG. 4, the magnetic sensor 1 according to the present embodiment may include a magnetic detection unit 2 including a first magnetic detection unit 2A and a second magnetic detection unit 2B, and a signal processing unit 3. The first magnetic detection unit 2A may have a first magnetoresistance effect element 40 whose sensitivity axis is parallel to the X-axis, and the second magnetic detection unit 2B may have a second magnetoresistance effect element 40 whose sensitivity axis is parallel to the Y-axis. The first magnetic detection unit 2A is for detecting a magnetic field parallel to the X-axis, and the second magnetic detection unit 2B is for detecting a magnetic field parallel to the Y-axis. However, when a magnetic field that is inclined and crosses both the X-axis and the Y-axis is applied to the magnetoresistance effect elements 40 of the first magnetic detection unit 2A and the second magnetic detection unit 2B, distortion errors included in the signals S output from each of the first magnetic detection unit 2A and the second magnetic detection unit 2B are superimposed, which may further deteriorate the linearity of the output signal from the magnetic sensor 1. The magnetic sensor 1 of this embodiment corrects the signal S output from each of the first magnetic detection unit 2A and the second magnetic detection unit 2B when an oblique magnetic field is applied using a correction value that can reduce the distortion error contained in the signal S to generate a corrected signal S', thereby achieving good linearity of the output signal from the magnetic sensor 1 regardless of the angle of the magnetic field applied to the magnetoresistance effect element 40 with respect to the sensitivity axis.

[0031] The magnetic sensor 1 according to this embodiment can be manufactured, for example, as follows. First, the first lead electrode 51, the second lead electrode 52, and the magnetoresistance effect element 40 are formed on a substrate. When forming the magnetoresistance effect element 40, the magnetization of the magnetization fixed layer 42 is fixed in a direction parallel to the minor axis direction of the magnetoresistance effect element 40, which has a substantially oval shape in a plan view.

[0032] Next, a test magnetic field that intersects the sensitivity axis (magnetization direction of the magnetization fixed layer 42) of the magnetoresistive element 40 at 45° is applied to the magnetoresistive element 40, and a test signal output from the magnetic detection unit 2 in response to the application of the test magnetic field is obtained. This test signal contains a distortion error due to a third harmonic component associated with the application of the oblique magnetic field. Therefore, a correction coefficient (correction value) capable of reducing the distortion error by half is obtained. Then, a signal processing unit 3 is created that stores the correction coefficient (correction value) thus obtained. In this way, the magnetic sensor 1 according to this embodiment can be manufactured.

[0033] The magnetic sensor 1 according to the present embodiment may be included in an electric control device. Examples of the electric control device according to the present embodiment include a magnetic field intensity sensor, a gaussmeter, an electronic compass, and a linear encoder. As described above, the magnetic sensor 1 according to the present embodiment can output a signal with good linearity regardless of the angle of the magnetic field applied to the magnetoresistance effect element 40 with respect to the sensitivity axis. Therefore, the magnetic sensor 1 according to the present embodiment is particularly useful as a sensor for detecting a direction in an electronic compass, which is used in an environment where a 360° magnetic field can be applied in the XY plane.

[0034] The above-described embodiments are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. In addition, the dimensions and layout of each element disclosed in the above embodiment are examples and are not limited to these. EXAMPLES

[0035] The present invention will be described in more detail below by way of examples, but the present invention is not limited to the following examples in any way.

[0036] [Test Example 1] In the magnetic sensor 1 having the configuration shown in FIG. 1 and including the magnetic detection unit 2 (see FIG. 2A) including the magnetoresistance effect element 40 (see FIG. 3), a signal S output from the magnetic detection unit 2 when a magnetic field parallel to the sensitivity axis (X-axis) of the magnetoresistance effect element 40 is applied was obtained by simulation. The results are shown in FIG. 5. In the graph shown in FIG. 5, the horizontal axis represents the standardized magnetic field strength (Standardized Magnetic Field) applied to the magnetoresistance effect element 40, and the vertical axis represents the output (Vout) of the magnetoresistance effect element 40 and the distortion error (Delta) due to the third harmonic component. As a result, the signal S did not include the distortion error due to the third harmonic component (Delta=0) and showed good linearity (see FIG. 5).

[0037] [Test Example 2] In the magnetic sensor 1 of Test Example 1, a signal S output from the magnetic detection unit 2 when a magnetic field intersecting the sensitivity axis (X-axis) of the magnetoresistance effect element 40 at 45° is applied was obtained by simulation. The results are shown in FIG. 6. In the graph shown in FIG. 6, the horizontal axis represents the standardized magnetic field strength (Standardized Magnetic Field) applied to the magnetoresistance effect element 40, and the vertical axis represents the output (Vout) of the magnetoresistance effect element 40 and the distortion error (Delta) due to the third harmonic component. As a result, the signal S includes a distortion error due to the third harmonic component, and the linearity is deteriorated compared to the signal S obtained in Test Example 1 (see FIG. 6).

[0038] [Test Example 3] A correction coefficient (correction value) capable of reducing the distortion error contained in the signal S obtained in the second test example by half was obtained, and the signal S obtained in the first test example was corrected using the above formula (1) to obtain a corrected signal S'. Similarly, the signal S obtained in the second test example was corrected to obtain a corrected signal S'. The results are shown in Figs. 7 and 8. In the graphs shown in Figs. 7 and 8, the horizontal axis represents the standardized magnetic field strength (Standardized Magnetic Field) applied to the magnetoresistance effect element 40, and the vertical axis represents the output (Vout) of the magnetoresistance effect element 40 and the distortion error (Delta) due to the third harmonic component.

[0039] As a result, the corrected signal S' obtained by correcting the signal S obtained in the test example 1 contained a distortion error due to the third harmonic component, and the corrected signal S' obtained by correcting the signal S obtained in the test example 2 contained a distortion error due to the third harmonic component (see FIG. 7). However, the corrected signal S' obtained by correcting the signal S obtained in the test example 2 showed better linearity than the signal S obtained in the test example 2 (see FIG. 8).

[0040] The maximum value MAX of the distortion error Er1 contained in the signal S obtained in the test example 1 Er1 (=0) and the maximum value MAX of the distortion error Er2 contained in the signal S obtained in Test Example 2 Er2 Difference (MAX Er1 -MAX Er2 ) and the maximum value MAX of the distortion error Er1' contained in the corrected signal S' obtained by correcting the signal S obtained in the test example 1. Er1’ and the maximum value MAX of the distortion error Er2' contained in the corrected signal S' obtained by correcting the signal S obtained in the test example 2. Er2’ Difference (MAX Er1’ -MAX Er2’ ) and the absolute value ABS' of the absolute value ABS were obtained and compared. As a result, the absolute value ABS' was 0.003% of the absolute value ABS. From this result, it was found that by correcting the signal S output from the magnetic detection unit 2 when an oblique magnetic field, preferably an oblique magnetic field inclined at 45° to the sensitivity axis (X-axis) is applied to the magnetoresistance effect element 40, using a correction value (correction coefficient a) capable of reducing distortion error contained in the signal S, the linearity of the output signal from the magnetic sensor 1 can be improved regardless of the angle of the magnetic field applied to the magnetoresistance effect element 40 with respect to the sensitivity axis. [Explanation of symbols]

[0041] 1...Magnetic sensor 2...Magnetic detection unit 2A…First magnetic detection unit 2B: Second magnetic detection unit 21...First element section 22...Second element section 23...Third element section 24…Fourth element section 3. Signal processing section 32...Arithmetic section 40...Magnetoresistance effect element 42...Magnetization fixed layer 44…free layer

Claims

[Claim 1] A magnetic detection unit that outputs a signal when a magnetic field is applied; a signal correction unit that corrects the signal output from the magnetic detection unit, the magnetic detection unit includes a magnetoresistance effect element having a predetermined sensitivity axis, The signal correction unit calculating, as a correction value, an inverse distortion capable of reducing by half the maximum value of the distortion error included in the signal output from the magnetic detection unit when the magnetic field is applied to the magnetoresistive element from a first intersecting direction in which the magnetic field in the intersecting direction, which is inclined with respect to the sensitivity axis and is a direction different from the sensitivity axis, indicates a maximum value of the distortion error included in the signal output from the magnetic detection unit when the magnetic field is applied to the magnetoresistive element from a first intersecting direction; a correction value for the inverse distortion is added to the signal output from the magnetic detection unit to correct the signal, the correction value being common to all intersecting directions in which the magnetic field intersects with the direction of the sensitivity axis at an angle greater than 0° and less than 90°, the intersecting direction including both a second intersecting direction in which the distortion error included in the signal output from the magnetic detection unit exhibits a minimum value and the first intersecting direction, thereby generating a correction signal; Magnetic sensor.

Images