JP2012127736A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor capable of accurately detecting, as an angle, a direction of a magnetic field with influence of intensity of the magnetic field eliminated.SOLUTION: A first sensor part 120 includes one or more magnetoresistance effect elements to be magnetically saturated by a magnetic field to be measured and outputs angle signals V1 and V2 in accordance with a direction of the magnetic field. A magnetoresistance effect element 30 of a second sensor part 130 is not magnetically saturated by the magnetic field B to be measured, and therefore, it may detect intensity of the magnetic field in an unsaturated region of its characteristic, namely, in a region where an output voltage is linearly changed against intensity change of the magnetic field. In a magnetic sensor of this invention, since a calculated value of an angle is corrected in accordance with an intensity signal V3, an angle error depending upon the intensity H of the magnetic field B to be measured may be reduced, so that a direction of the magnetic field may be accurately detected as an angle.

Description

  The present invention relates to a magnetic sensor using a magnetoresistive effect element.

  Magnetic sensors using magnetoresistive elements are used in various fields in the industry. For example, in the field of automobiles, they are used for detecting the rotation angle and speed of a steering wheel. As a magnetic sensor, as disclosed in Patent Documents 1 and 2, a bridge circuit composed of a magnetoresistive element is generally used. In the bridge circuit, the magnetoresistive effect element operates in the magnetization saturation region so that an output error caused by variation in characteristics during manufacture does not occur.

  In this type of magnetic sensor, it is known that an error in sensor response with respect to the direction of a magnetic field to be measured changes depending on the strength of the magnetic field. This becomes a problem particularly when there is an error in the mounting position of the magnetic sensor that generates the magnetic field. According to the inventor's estimation, for example, when the strength of the magnetic field is reduced from 300 (Oe) to 200 (Oe), the angle error is about 0.6 (deg.) To 1.1 (deg.), Which is about twice. It is known that there may be an increase.

  Patent Document 1 discloses a technique for compensating for an error in the magnetization direction between pinned layers of different magnetoresistive elements, in which the difference between them should be exactly 90 degrees, while Patent Document 2 discloses Discloses a technique for compensating for an error in an angle calculated from an arctangent function caused by waveform distortion.

  However, none of them disclose a technique for compensating the angle error according to the strength of the magnetic field.

Japanese Patent No. 4194484 Japanese Patent No. 4194485

  An object of the present invention is to provide a magnetic sensor that can accurately detect the direction of the magnetic field as an angle while eliminating the influence of the strength of the magnetic field.

1. 1st aspect In order to solve the subject mentioned above, the magnetic sensor which concerns on this invention contains a 1st sensor part and a 2nd sensor part, and detects the direction of the magnetic field which is a measuring object as an angle.

  The first sensor unit includes one or more magnetoresistive elements that are saturated with magnetization by the magnetic field, and outputs an angle signal corresponding to the direction of the magnetic field.

  According to the magnetic sensor of the present invention, the first sensor unit includes one or more magnetoresistive elements that are magnetized and saturated by the magnetic field to be measured, and outputs an angle signal corresponding to the direction of the magnetic field.

  The second sensor unit includes one or more magnetoresistive effect elements that are not magnetized by the magnetic field, and outputs an intensity signal corresponding to the intensity of the magnetic field. The magnetic sensor according to the present invention is characterized in that the angle is obtained based on the angle signal and the intensity signal in order to obtain the angle with high accuracy.

  According to this configuration, since the magnetoresistive effect element of the second sensor unit does not saturate magnetization due to the magnetic field to be measured, the second sensor unit has an unsaturated region in its characteristics, that is, a change in the strength of the magnetic field. In contrast, the strength of the magnetic field can be detected in a region where the output voltage changes linearly. On the other hand, since the magnetoresistive effect element of the first sensor unit operates in a saturation region where there is substantially no change in output voltage as described above, the strength of the magnetic field is different from the second sensor unit. Cannot be detected. That is, the magnetic sensor according to the present invention has a characteristic configuration in which the first sensor unit exclusively for detecting the direction of the magnetic field is combined with the second sensor unit for detecting the strength of the magnetic field.

  Since the magnetic sensor according to the present invention obtains an angle based on the angle signal and the intensity signal, an angle corrected according to the intensity signal is obtained to reduce an angle error depending on the intensity of the magnetic field to be measured. The direction of the magnetic field can be accurately detected as an angle.

2. Second Mode A magnetic sensor according to the present invention includes a first sensor unit, a second sensor unit, an angle calculation unit, and an attachment position analysis unit, and detects the direction of a magnetic field that is a measurement target.

  The first sensor unit includes one or more magnetoresistive elements that are saturated with magnetization by the magnetic field, and outputs an angle signal corresponding to the direction of the magnetic field. The angle calculation unit calculates an angle based on the angle signal.

  According to the magnetic sensor of the present invention, the first sensor unit includes one or more magnetoresistive effect elements that are magnetized and saturated by the magnetic field to be measured, and outputs an angle signal corresponding to the direction of the magnetic field. The angle calculation unit can calculate the angle based on the angle signal and detect the direction of the magnetic field.

  The magnetic sensor according to the present invention is characterized in that the second sensor unit includes one or more magnetoresistive effect elements that are not magnetized and saturated by the magnetic field, and outputs an intensity signal corresponding to the intensity of the magnetic field. is there.

  According to this configuration, the magnetoresistive effect element of the second sensor unit does not saturate magnetization due to the magnetic field to be measured, and therefore detects the strength of the magnetic field in the unsaturated region as in the first embodiment. be able to.

  A further feature of the magnetic sensor according to the present invention is that the mounting position analysis unit includes a magnetic force distribution recording unit that records a spatial distribution of the magnetic field direction and intensity, and the angle and the intensity based on the spatial distribution. The point is to specify the position in the space from the signal.

  Therefore, by specifying the position in the space where the error of the calculation angle of the angle calculation unit is minimized in advance, the positional error from the current position of the magnetic sensor specified using the direction and intensity of the magnetic field as a clue. Can be detected and the position or positional error can be corrected accordingly.

  As described above, according to the present invention, it is possible to provide a magnetic sensor that can eliminate the influence of the strength of the magnetic field and can accurately detect the direction of the magnetic field as an angle.

It is a top view of the magnetic sensor which concerns on this invention. It is a side view of the magnetic sensor which concerns on this invention. It is a circuit diagram of the 1st sensor part. It is sectional drawing of a TMR element. It is a graph which shows the change of the output voltage of the 1st sensor part with respect to the change of the direction of the magnetic field which is a measuring object. It is a graph which shows the change of the error of the detected angle with respect to the intensity | strength change of the magnetic field which is a measuring object. It is a graph which shows the change of the output voltage of a magnetoresistive effect element with respect to the intensity | strength change of this magnetic field when the direction of the magnetic field which is a measuring object is made constant. It is an electrical block diagram of the magnetic sensor which concerns on this invention. It is an electrical block diagram of the magnetic sensor which concerns on other embodiment. It is an electrical block diagram of the magnetic sensor which concerns on other embodiment. It is an electrical block diagram of the magnetic sensor which concerns on this invention of another aspect. It is a schematic diagram of the magnetic flux and magnetic force spatial distribution in the example of FIG. It is a top view of the magnetic sensor which concerns on other embodiment. It is sectional drawing of IC package containing a magnetoresistive effect element. It is sectional drawing of the IC package containing a magnetoresistive effect element based on other embodiment. It is sectional drawing of the IC package containing the magnetoresistive effect element based on further another embodiment. FIG. 17 is a plan view of the IC package shown in FIG. 16. It is the external appearance of the rotation speed detection apparatus to which the magnetic sensor which concerns on this invention is applied. It is a fragmentary sectional view along the BB line of FIG. FIG. 20 is a schematic diagram of a spatial distribution of magnetic force and angle error in the example of FIG. 19.

  FIG. 1 is a plan view of a magnetic sensor according to the present invention, and FIG. 2 is a side view of the magnetic sensor. 1 and 2 show the appearance of a rotation angle sensor applied to a handle or the like.

  The circular rotating shaft 4 is, for example, an axis that interlocks with the rotation of the handle, and rotates in the direction R around the position o. An N-pole side magnet 41 and an S-pole side magnet 42 are formed on the circular end surface of the rotating shaft 4 so as to be divided into two. In the N-pole side magnet 41 and the S-pole side magnet 42, the magnetic field B rotates with the rotation of the rotary shaft 4 around the position indicated by the symbol o. This magnetic field B is a measurement target of the magnetic sensor according to the present invention.

  The magnetic sensor substrate 5 is installed on the base 51 so that the plate surface faces the surface 43 of the magnets 41 and 42. The magnetic sensor substrate 5 is a substantially rectangular substrate, and nine magnetoresistive elements 11 to 14, 21 to 24, and 30 are mounted on the plate surface. Among these, the magnetoresistive effect elements 11 to 14 and 21 to 24 are used to detect the direction of the rotating magnetic field B, that is, the angle formed by the magnetic flux at the center o.

  On the other hand, the remaining one magnetoresistive element 30 is located substantially at the center o and is used for detecting the strength of the magnetic field B. The magnetoresistive effect element 30 is preferably arranged as close as possible to these in order to detect the strength of the magnetic field B received by the other magnetoresistive effect elements 11 to 14 and 21 to 24. In any of the magnetoresistive effect elements 11 to 14, 21 to 24, and 30, the film surface of the free layer is substantially the same as the surface 43 of the magnets 41 and 42 in order to detect the component of the magnetic field B in the XY plane in the figure. Are fixed so that they are parallel to each other.

  The magnetoresistive effect elements 11 to 14 and 21 to 24 constitute a first sensor unit for detecting an angle with a TMR element. Instead of the TMR element, the first sensor unit may be configured using a GMR element. A circuit diagram of the first sensor unit is shown in FIG. The first sensor unit includes first and second bridge circuits 1 and 2 including first to fourth TMR elements 11 to 14 and 21 to 24, respectively.

  In the first bridge circuit 1, a first TMR element 11 and a second TMR element 12, and a third TMR element 13 and a fourth TMR element 14 are connected in series, and these series circuits are parallel to each other. Become connected. The connection end of the first TMR element 11 and the third TMR element 13 is connected to the power supply terminal Vcc, and the connection end of the second TMR element 12 and the fourth TMR element 14 is connected to the ground terminal GND. Yes.

  The connection end of the first TMR element 11 and the second TMR element 12 is connected to the output terminal T12, and the connection end of the third TMR element 13 and the fourth TMR element 14 is connected to the output terminal T11. Yes. The potential of the output terminal T11 with respect to the output terminal T12 is detected as the first output voltage V1.

  On the other hand, in the second bridge circuit 2, the first to fourth TMR elements 21 to 24 are connected in the same manner as the first bridge circuit 1, and the potential of the output terminal T21 with respect to the output terminal T22 is the second. Is detected as an output voltage V2. Such a circuit configuration is merely an example, and the first sensor unit may be configured by one magnetoresistive element.

  As shown in FIG. 4, each of the TMR elements 11 to 14 and 21 to 24 has a structure in which an antiferromagnetic layer 101, a pinned layer 102, an insulating layer 103, and a free layer 104 are stacked in this order. As is well known, the magnetization direction D2 of the free layer 104 changes according to the external magnetic field, whereas the magnetization direction D1 of the pinned layer 102 is fixed. The arrows attached to the first to fourth TMR elements 11 to 14 and 21 to 24 shown in FIG. 3 indicate the magnetization direction D1 of the pinned layer 102. The insulating layer 103 functions as a tunnel barrier. The magnetoresistive effect element 30 for detecting the intensity may also be a TMR element or a GMR element. However, when the TMR element is employed, it has a layer structure shown in FIG.

  In the first bridge circuit 1, with respect to the magnetization direction of the pinned layer 102, the first TMR element 11 and the fourth TMR element 14, and the second TMR element 12 and the third TMR, which are in an opposing relationship on the circuit diagram. The elements 13 are the same as each other. The magnetization directions of the pinned layers 102 of the first TMR element 11 and the fourth TMR element 14 and the magnetization directions of the pinned layers 102 of the second TMR element 12 and the third TMR element 13 are antiparallel to each other. (The opposite).

  On the other hand, in the second bridge circuit 2, with respect to the magnetization direction of the pinned layer 102, the first TMR element 21 and the fourth TMR element 24, and the second TMR element 22 that are in the opposite relationship on the circuit diagram are similarly shown. And the third TMR element 23 are the same as each other. The magnetization directions of the pinned layers 102 of the first TMR element 21 and the fourth TMR element 24 and the magnetization directions of the pinned layers 102 of the second TMR element 22 and the third TMR element 23 are antiparallel to each other. Are in a relationship.

  As indicated by the arrows in FIG. 3, the TMR elements 11 to 14 of the first bridge circuit 1 and the TMR elements 21 to 24 of the second bridge circuit 2 have a relationship in which the magnetization directions of the pinned layer 102 are orthogonal to each other. It is in.

  As is well known, the characteristic of the TMR element is that the resistance value is minimized when the magnetization direction of the pinned layer 102 and the magnetization direction of the free layer 104 are the same, and the resistance value is maximized when they are antiparallel (the opposite). It is to become. Based on this, changes in resistance values of the TMR elements 11 to 14 and 21 to 24 with respect to the angle θ formed by the rotating magnetic field B shown in FIG. 3 will be described. Note that the angle θ is defined to indicate 0 degree when the direction of the rotating magnetic field B is the same as the magnetization direction of the pinned layer 102 of the first TMR element 11 and the fourth TMR element 14.

  First, when the angle θ is 0 degree, in the first bridge circuit 1, the resistance values of the first TMR element 11 and the fourth TMR element 14 are minimized, and the second TMR element 12 and the third TMR element The resistance value of the element 13 is maximized. On the other hand, in the second bridge circuit 2, the resistance values of the TMR elements 21 to 24 are intermediate values between the maximum value and the minimum value.

  Next, when the angle θ is 90 degrees, that is, when the direction of the external magnetic field B is the same as the magnetization direction of the pinned layer 42 of the TMR elements 22 and 23, each TMR element The resistance values 11 to 14 are intermediate values between the maximum value and the minimum value. On the other hand, in the second bridge circuit 2, the resistance values of the first TMR element 21 and the fourth TMR element 24 are maximized, and the resistance values of the second TMR element 22 and the third TMR element 23 are minimized. .

  Next, when the angle θ is 180 degrees, in the first bridge circuit 1, the resistance values of the first TMR element 11 and the fourth TMR element 14 are maximized, and the second TMR element 12 and the third TMR element 14 The resistance value of the TMR element 13 is minimized. On the other hand, in the second bridge circuit 2, the resistance values of the TMR elements 21 to 24 are intermediate values between the maximum value and the minimum value.

  Finally, when the angle θ is 270 degrees, in the first bridge circuit 1, the resistance values of the TMR elements 11 to 14 are intermediate values between the maximum value and the minimum value. On the other hand, in the second bridge circuit 2, the resistance values of the first TMR element 21 and the fourth TMR element 24 are minimized, and the resistance values of the second TMR element 22 and the third TMR element 23 are maximized. .

  Therefore, as shown in FIG. 5, the output voltage V1 (V) of the first bridge circuit 1 forms a COS function-like waveform with respect to the change in the angle θ, while the output of the second bridge circuit 2 The voltage V2 (V) has a SIN function waveform with respect to the change in the angle θ. The TMR elements 11 to 14 and 21 to 24 all have the same characteristics.

Based on this fact, the angle θ of the detection target can be obtained from the output voltages V1 (V) and V2 (V) by the following formula.
(Formula 1) θ = arctan (V2 / V1)
As described above, the rotation angle sensor shown in FIGS. 1 and 2 can detect the rotation angle of the rotation shaft 4 by detecting the magnetic field B by the TMR elements 11 to 14 and 21 to 24.

  However, as described above, the angle θ thus calculated includes an error depending on the intensity of the magnetic field B. FIG. 6 is a graph showing a change in the detected angle error Δθ with respect to a change in the intensity H of the magnetic field B to be measured.

  As understood from the figure, the angle error Δθ depends on the intensity H of the magnetic field B, and shows a characteristic of a substantially quadratic function that has a minimum value at the intensity Ho.

  The first aspect of the magnetic sensor according to the present invention calculates the angle θ of the magnetic field B by the magnetoresistive effect elements 11 to 14 and 21 to 24 for angle detection, and uses the magnetoresistive effect element 30 for intensity detection to calculate the magnetic field. The intensity H of B is detected and used for correcting the angle θ.

  On the other hand, in the second aspect of the magnetic sensor according to the present invention, the angle θ of the magnetic field B is detected by the magnetoresistive effect elements 11 to 14 and 21 to 24 for angle detection, and the magnetic field B is detected by the magnetoresistive effect element 30. The intensity H is detected, and based on the spatial distribution of the magnetic force of the magnetic field B, the mounting position of the magnetic sensor is adjusted to the position of the optimum intensity Ho that gives the minimum angular error Δθ. In addition, in the application example to the rotation angle sensor shown in FIG. 1, it is necessary to adjust the mounting positions and strengths of the magnets 41 and 42 in advance so that the rotation center o becomes the strength Ho.

  As described above, the magnetic sensor according to the present invention is characterized in that the function is shared by the magnetoresistance effect elements 11 to 14 and 21 to 24 for angle detection and the magnetoresistance effect element 30 for intensity detection. The difference in operation between the magnetoresistive effect elements 11 to 14 and 21 to 24 for angle detection and the magnetoresistive effect element 30 for intensity detection is understood with reference to FIG.

  FIG. 7 is a graph showing changes in the output voltage of the magnetoresistive effect elements 11 to 14, 21 to 24, and 30 with respect to changes in the magnetic field strength H when the direction of the magnetic field B to be measured is made constant. As understood from the figure, the characteristics are the unsaturated region S1 in which the output voltage Vout changes in a substantially linear shape with respect to the magnetic field strength H with the strength Hs as a boundary, and the output voltage Vout is a substantially constant value. It is divided into a saturation region S2 indicating Vs.

  As described above, in order to avoid the influence of the characteristic variation at the time of manufacture, the operating points of the magnetoresistive effect elements 11 to 14 and 21 to 24 for angle detection exist in the saturation region S2. On the other hand, the magnetoresistive effect element 30 for intensity detection has an operating point in the unsaturated region S1 in order to detect the intensity from the output voltage.

  Thus, in order to divide the operating points of the magnetoresistive effect elements 11 to 14, 21 to 24, and 30 according to the purpose, the magnetoresistive effect elements 11 to 14, 21 to 24 for angle detection are separated by the magnetic field B. On the other hand, it is necessary that the magnetoresistance effect element 30 for intensity detection is not saturated with the magnetic field B.

  Various methods are conceivable as specific methods for realizing this. For example, the magnetoresistive effect element 30 for intensity detection is compared with the magnetoresistive effect elements 11 to 14 and 21 to 24 for angle detection. The thickness of the layer and / or the free layer may be increased. Alternatively, the magnetoresistance effect element 30 for intensity detection may have a horizontally long shape extending in the magnetization direction so as to have shape anisotropy in the magnetization direction of the pinned layer. Here, the thickness or length needs to be appropriately determined according to the strength of the magnetic field B. Further, other forms will be described later.

  First, a first aspect of the magnetic sensor according to the present invention will be described. FIG. 8 is an electrical configuration diagram of the magnetic sensor. The magnetic sensor includes the first sensor unit 120, the second sensor unit 130, the angle calculation unit 121, and the angle table reference unit 132 described above.

  The first sensor unit 120 includes the circuit shown in FIG. 3, and outputs the first and second voltages V1 and V2 to the angle calculation unit 121 as angle signals corresponding to the direction of the magnetic field B.

  On the other hand, the second sensor unit 130 includes a circuit in which a magnetoresistive effect element 30 for intensity detection and a normal resistance element 31 are connected in series. The magnetoresistive effect element 30 is connected to the power source Vcc, the resistance element 31 is grounded, and the output voltage V3 from the contact of this series circuit is output to the angle table reference unit 132 as an intensity signal corresponding to the intensity H of the magnetic field B. Is done. Here, the configuration of the second sensor unit 130 is not limited to such a circuit, and two or more magnetoresistive elements may be connected in series, or may be a bridge circuit. May be. In the former case, the voltage difference between both ends of the series circuit is output as the output voltage V3.

  The angle table reference unit 132 is typically composed of a nonvolatile memory, and the angle θo (deg.) Corresponding to the voltages V1 and V2 (V) is recorded and held as a table. This angle θo (deg.) Changes according to the input intensity signal V3, and is output as a value reflecting the corresponding correction amount. That is, the angle table reference unit 132 is a table having not only the angle θ but also the correction amount. Such a table is obtained from numerical values converted into data based on actual measurement.

  FIG. 9 shows the electrical configuration of a magnetic sensor according to another embodiment. Here, portions common to the circuit diagram of the previous embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, unlike the previous embodiment, a signal correction unit 123 is provided in order to correct the angle signals V1 and V2 themselves in the previous stage of the angle calculation unit 121. The signal correction unit 123 is configured by an arithmetic processing circuit, for example, and the correction amount of the angle signals V1 and V2 corresponding to the intensity signal V3 from the second sensor circuit 130 is an approximate expression or a table similar to the previous embodiment. And output to the angle calculator 121 as corrected angle signals V10 and V20. Then, the angle calculation unit 121 can calculate the corrected angle θo according to the following equation.
(Formula 2) θo = arctan (V20 / V10)
FIG. 10 shows an electrical configuration of a magnetic sensor according to still another embodiment. Here, portions common to the circuit diagram of the previous embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, unlike the previous embodiment, a correction amount calculation unit 124 for correcting the angle θ calculated by Expression 1 is provided at a later stage of the angle calculation unit 121. Based on the calculated angle θ and the intensity signal V3 from the second sensor circuit 130, the correction amount calculation unit 124 obtains the corrected angle θo according to an approximate expression or a table similar to the previous embodiment. As an approximate expression, for example, the following expression can be used.
(Formula 3) θo = θ−β (V3) sin4 {θ−dθ}
Here, β (V3) is an amplitude correction amount based on the intensity signal V3, and dθ is a predetermined phase correction amount or a phase correction amount based on the intensity signal V3.

  According to the magnetic sensor of the present invention, the first sensor unit 120 includes one or more magnetoresistive effect elements 11 to 14 and 21 to 24 that are magnetized and saturated by the magnetic field B that is a measurement target. The corresponding angle signals V1 and V2 are output, and the direction of the magnetic field B can be detected as an angle in the saturation region S2 on the characteristics of the magnetoresistive effect element. Therefore, the magnetic sensor according to the present invention can detect the direction of the magnetic field B without being affected by variations in the characteristics of the magnetoresistive effect elements 11 to 14 and 21 to 24.

  In the magnetic sensor according to the present invention, since the magnetoresistive effect element 30 of the second sensor unit 130 is not magnetized and saturated by the magnetic field B to be measured, the second sensor unit 130 is not saturated due to its characteristics. The intensity of the magnetic field B can be detected in the area S1, that is, the area where the output voltage changes with respect to the change in the intensity H of the magnetic field B. On the other hand, the magnetoresistive effect elements 11 to 14 and 21 to 24 of the first sensor unit 120 operate in the saturation region S2 where there is substantially no change in the output voltage as described above. Unlike the sensor unit 130, the intensity H of the magnetic field B cannot be detected. That is, the magnetic sensor according to the present invention has a characteristic configuration in which the first sensor unit 120 for detecting the direction of the magnetic field B is combined with the second sensor unit 130 for detecting the intensity H of the magnetic field B. It has.

  The magnetic sensor according to the present invention obtains the angle θo based on the angle signals V1 and V2 and the intensity signal V3, thereby obtaining an angle corrected according to the intensity signal V3, and the magnetic field B to be measured. The angle error Δθ that depends on the intensity H of the magnetic field B can be reduced, and the direction of the magnetic field B can be accurately detected as an angle.

  Next, a second aspect of the magnetic sensor according to the present invention will be described. FIG. 11 shows an example of the electrical configuration of the magnetic sensor in this embodiment. Here, portions common to FIGS. 8 to 9 are denoted by the same reference numerals, and description thereof is omitted.

  The magnetic sensor of this mode is for correcting the mounting position of the magnetic sensor in addition to the sensing unit M1 including the first and second sensor units 120 and 130 and the angle detection unit 121 similar to the first mode. An attachment position analysis unit M2 is provided. The sensing unit M1 outputs the angle θ calculated by Equation 1 and the intensity signal V3 to the attachment position analysis unit M2.

  The attachment position analysis unit M2 includes an attachment error detection unit 141, a magnetic force distribution recording unit 142, and a position correction amount display unit 143. The attachment position analysis unit M2 is not necessarily provided in a form included in the sensor body, and a part or all of the attachment position analysis unit M2 may be configured as an attachment device that can be attached to the sensor body.

  The magnetic force distribution recording unit 142 is configured by a non-volatile memory or the like, and records the direction of the magnetic field B to be measured and the spatial distribution of intensity. FIG. 12 is a schematic diagram of the direction of the magnetic field B and the spatial distribution of intensity in the case of the rotation angle sensor shown in FIG.

  The magnetic force distribution recording unit 142 records the direction and strength of the magnetic field B as shown in FIG. 12, that is, the magnetic field vector distribution in the XY plane in the drawing for each position. As data recorded in the magnetic force distribution recording unit 142, for example, the direction of the magnetic field vector B at each position (Xi, Yi) when the XY plane is divided into Nx × Ny (pieces) with a constant step size. A recording of components (Hx, Hy) is conceivable. Alternatively, the angle and magnitude of the XY in-plane component of the magnetic field vector B at each position (Xi, Yi) may be recorded. Such magnetic force spatial distribution data can be obtained by computer analysis using a finite element method or the like.

  The attachment error detection unit 141 identifies the position P in the space from the calculated angle θ and the intensity signal V3 based on the spatial distribution recorded in the magnetic force distribution recording unit 142. As a specific example, first, the intensity H of the magnetic field B is calculated from the intensity signal V3, and the direction component (Hix, Hiy) of the magnetic field vector B is calculated from the intensity H and the calculated angle θ. Then, the attachment error detection unit 141 compares the direction components (Hix, Hiy) with the individual direction components (Hx, Hy) recorded in the magnetic force distribution recording unit 142, and these values match or are close to each other. The position (Xi, Yi) indicating is detected. Alternatively, the intensity H and the calculated angle θ may be compared with the angle and size of the recorded magnetic field vector B.

  Since the calculated angle θ includes an angle error Δθ, the spatial distribution data of the magnetic force distribution recording unit 142 is set to a value including the error, or before the comparison process described above. In the stage, it is necessary to correct the calculated angle θ by the method described above.

  Further, in order to match the position (Xi, Yi) on the spatial distribution recorded in the magnetic force distribution recording unit 142 with the actual position on the XY plane, for example, the rotation angle θ = 0 ( deg.), it is necessary to fix the magnets 41 and 42 at predetermined positions.

  After the position is specified, the attachment error detection unit 141 detects the error of the specified position with respect to the reference position where the error Δθ of the calculated angle θ is minimum. In the case of the rotation sensor shown in FIG. 1, the position of the magnets 41 and 42 and the magnetic force are set so that the angle error Δθ is minimized at the center o as described above. Calculates the errors ΔX, ΔY of the current sensor position P with respect to the center o, and outputs them to the position correction amount display unit 143. That is, if the specified position is (Xp, Yp) and the position of the center o on the spatial distribution recorded in the magnetic force distribution recording unit 142 is (Xo, Yo), the error on the X axis ΔX = Xp−Xo, The error on the Y axis is ΔY = Yp−Yo.

  The position correction amount display unit 143 is a liquid crystal display device, for example, and displays the errors ΔX and ΔY in a digital or analog manner. When the magnetic sensor is attached, the attachment position of the sensor substrate 5 can be corrected according to this display.

  As described above, the feature of the second aspect of the magnetic sensor according to the present invention is that the attachment position analysis unit M2 includes the magnetic field distribution recording unit 142 that records the direction of the magnetic field B and the spatial distribution of the strength H. Based on the spatial distribution, the position in the space is specified from the angle θ and the intensity signal V3.

  Therefore, by specifying the position o (Xo, Yo) in the space where the error Δθ of the calculation angle θ of the angle calculation unit is minimized, the magnetic field direction θ and the intensity H are specified as clues. It is possible to detect positional errors ΔX and ΔY from the current position P of the magnetic sensor 5 and correct the positions accordingly.

  In the embodiment described above, the sensor substrate 5 is provided with only one magnetoresistive effect element 30 for intensity detection, but the present invention is not limited to this. For example, as shown in FIG. 13, four strength detecting magnetoresistive elements 32 to 35 may be provided.

  In this embodiment, each of the magnetoresistance effect elements 32 to 35 for strength detection is sandwiched between two magnetoresistance effect elements 11 to 14 and 21 to 24 for angle detection in which the magnetization directions of the pinned layers are the same. It is provided as follows. These are configured as a single IC package as indicated by the dotted frame in the figure. FIG. 14 is a schematic cross-sectional view of an IC package typically including the magnetoresistive elements 12, 13, and 35 as viewed from the side surface in the longitudinal direction. The other IC packages have the same configuration.

As understood from the drawing, the magnetoresistive elements 12 and 13 for angle detection are sandwiched between a pair of magnetic films 36 arranged on both sides thereof so that the magnetization is saturated by the magnetic field B. The magnetic film 36 is made of a soft magnetic material such as NiFe or XFe ₂ O ₄ (X = Mn, Cu, Zn).

  Each pair of the magnetic films 36 sandwiches the magnetoresistive effect elements 12 and 13 and functions as a yoke. Therefore, the intensity H of the magnetic field B received by each of the magnetoresistive elements 12 and 13 increases, and the magnetoresistive elements 12 and 13 can operate in the saturation region S2. In this case, it is necessary to appropriately set the shape and size of the magnetic film 36 and the distance between the magnetoresistive effect elements 12 and 13.

  On the contrary, as shown in FIG. 15, the magnetoresistive element 35 for detecting the intensity is shielded by the magnetic film 39 made of the soft magnetic material so as not to be saturated with the magnetic field B, as shown in FIG. May be.

  The magnetic film 39 is disposed between the magnets 41 and 42 and the magnetoresistive element 35 shown in FIGS. 1 and 2 and functions as a shield against the magnetic field B. Accordingly, the intensity H of the magnetic field B received by the magnetoresistive effect element 35 is reduced, and the operation of the magnetoresistive effect element 35 in the unsaturated region S1 is enabled. In this case, it is necessary to appropriately set the shape and size of the magnetic film 39 and the distance between the magnetoresistive effect element 35 and the like.

  Means for making the operating point of the magnetoresistive element different is not limited to the magnetic films 36 and 39. As shown in FIGS. 16 and 17, a magnet 37 may be provided above the magnetic resistance B so that the strength H of the magnetic field B received by the magnetoresistive element 35 is lowered. At this time, the magnet 37 is fixed at a predetermined position by fixing means such as a metal fitting.

  In fixing the magnet 37, it is desirable to use a position adjusting plate 38 indicated by a dotted line in the drawing as a jig in order to place the magnet 37 directly above the magnetoresistive element 35. The position adjustment plate 38 is a rectangular plate having substantially the same dimensions as the IC package 50, and detection elements 381 are provided at four corners of the plate surface.

  The detection element 381 is a magnetoresistive effect element having the same function as the magnetoresistive effect elements 32 to 35 for intensity detection. That is, the detection element 381 does not saturate due to the magnetic field emitted from the magnet 37, and operates in an unsaturated region in terms of characteristics to detect the intensity.

  The four detection elements 381 are arranged symmetrically with respect to the center of the plate surface, and the magnetoresistive element 35 is arranged at the center of the plate surface. At this time, if the magnet 35 is inclined or the position of the magnet 35 is deviated from the center, a difference is generated in the intensity detected by the four detection elements 381, and this can be detected.

  14 to 17, the magnetic films 36 and 39 or the magnet 37 are used to detect the magnetoresistance effect elements 32 to 35 for strength detection and the magnetoresistance effect elements 11 to 14 and 21 to 24 for angle detection. A difference occurs in the magnetic field strength H. Accordingly, it is desirable that the magnetoresistance effect elements 32 to 35 for detecting the intensity and the magnetoresistance effect elements 11 to 14 and 21 to 24 for detecting the angle have the same configuration and characteristics, and further, the correction value described above. It should be noted that the difference in strength H needs to be compensated based on the magnetic permeability of the magnetic films 36 and 39 or the magnetic force of the magnet 37 in calculating the position and specifying the position.

  The advantage of adopting the configuration shown in FIG. 13 as the sensor substrate 5 is that the magnetoresistance effect elements 32 to 35 for intensity detection and the magnetoresistance effect elements 11 to 14 and 21 to 24 for angle detection are the same. By mounting in an IC package, the mounting area and cost can be reduced, and both can be placed closer to each other. As a result, the above-described correction value calculation and position specification can be performed with high accuracy. It is in the point that can In addition, since the magnetoresistive effect elements 32 to 35 for detecting the strength are arranged at four positions symmetrical with respect to the center of the plate surface of the sensor substrate 5, when the sensor substrate 5 is mounted at an inclination, the magnetoresistive effect A difference arises in each intensity | strength H which the elements 32-35 detected, and the secondary effect that this can be detected is also acquired. This is similar to the effect of the position adjustment plate 38 described above.

  Further, in the configuration shown in FIG. 13, the magnetization directions of the pinned layers of the magnetoresistance effect elements 32 to 35 for detecting the intensity are mutually changed in the same manner as the magnetoresistance effect elements 11 to 14 and 21 to 24 for angle detection. It is good to set in two orthogonal directions. Thereby, the intensity H of the magnetic field B can be immediately calculated by calculating the mean square of the SIN component and the COS component, and the detection angle can be corrected. On the other hand, when the magnetization directions of the pinned layers of the magnetoresistive effect elements 32 to 35 for intensity detection are all in a predetermined direction, the SIN component and the COS component of intensity H are detected when the rotation angle sensor is activated. Therefore, an extra process for rotating the magnets 41 and 42 shown in FIGS. 1 and 2 by at least 90 degrees is required.

  The application range of the magnetic sensor according to the present invention is not limited to the rotation angle sensor shown in FIGS. 18 and 19 show an example in which the magnetic sensor according to the present invention is applied to a rotational speed sensor. This configuration is often used when the configuration in which the sensor substrate 5 is arranged at the end of the shaft shown in FIGS. 1 and 2 cannot be employed due to mechanical limitations.

  In the rotation speed sensor, an annular multipolar magnet 7 is fixed around a cylindrical shaft 6 that rotates in the R direction around the position o via a fitting or the like. The multipolar magnet 7 is provided with N pole magnets 71 and S pole magnets 72 alternately along the circumference, for example, a total of ten.

  The sensor substrate 5 is attached to a mounting base 52 and is arranged so that its plate surface is substantially perpendicular to the rotation surface of the multipolar magnet 7. That is, the film surfaces of the free layer 104 of the magnetoresistive effect elements 11 to 14, 21 to 24, and 30 are substantially parallel to the XZ plane in the drawing. Thereby, the magnetic sensor can detect the direction of the magnetic field which changes with rotation of the multipolar magnet 7 as an angle.

  And a magnetic sensor can correct | amend a calculation angle by providing an electrical structure like FIG. 8 thru | or 10 in a previous example. However, in the case of this example, unlike the previous example, since the three-dimensional distortion of the magnetic field is large due to the multipolar magnet 7, the correction of the calculated angle and the spatial of the magnetic field generated from the multipolar magnet 7 are simultaneous. It is also necessary to correct various distortions by vector calculation.

  On the other hand, if the magnetic sensor has an electrical configuration as shown in FIG. 11 in the previous example, it is possible to adjust the mounting position as described above. In this case, for example, it is conceivable to record the magnetic force spatial distribution in the magnetic force distribution recording unit 142 with respect to the XZ plane indicated by the dotted line 8 in the drawing. FIG. 20 is an example of the spatial distribution.

  In the XZ plane shown in FIG. 20, in addition to the spatial distribution of magnetic force, the distribution of angular errors around the magnet 72 obtained by computer analysis is also described. It should be noted that the intensity of the magnetic field indicated by the dotted line in the figure is a component in the XZ plane of the magnetic field vector B, and thus there is no correlation with the distribution of angular errors on the drawing. I want.

  Based on this error distribution, the installation error detection unit 141 can detect the positional error of the current position P of the substrate 5 with the position of the symbol Po, which is the minimum error, as the target position, for example. Since there are mechanical restrictions on installation, the target position does not necessarily have to be a position that causes a minimum error.

  In both of the present example and the previous example, the correction of the mounting position of the magnetic sensor in the two-dimensional space is illustrated, but the position can be corrected in the same manner in the three-dimensional space. In this case, in order to detect the components (Hx, Hy, Hz) in the three directions of the magnetic field vector, at least two sets of first and second sensor units in which the film surfaces of the magnetoresistive effect element are orthogonal to each other are required. .

  Although the contents of the present invention have been specifically described above with reference to the preferred embodiments, it is obvious that those skilled in the art can take various modifications based on the basic technical idea and teachings of the present invention. It is.

DESCRIPTION OF SYMBOLS 5 Sensor substrate 11-14, 21-24, 30, 32-35 Magnetoresistive element 15, 36 Magnetic film 120 1st sensor part 130 2nd sensor part 121 Angle calculation part 132 Correction table recording part 142 Magnetic field distribution recording Part B Magnetic field V1, V2 Angle signal V3 Strength signal M2 Mounting position analyzer

Claims (9)

A magnetic sensor that includes a first sensor unit and a second sensor unit, and detects a direction of a magnetic field as a measurement target as an angle,
The first sensor unit includes one or more magnetoresistance effect elements that are saturated with magnetization by the magnetic field, and outputs an angle signal corresponding to the direction of the magnetic field,
The second sensor unit includes one or more magnetoresistance effect elements that are not magnetized and saturated with the magnetic field, and outputs an intensity signal corresponding to the intensity of the magnetic field,
The angle is obtained based on the angle signal and the intensity signal.
Magnetic sensor. The magnetic sensor according to claim 1,
An angle calculation unit that calculates an angle based on the angle signal;
Magnetic sensor. The magnetic sensor according to claim 1 or 2,
A table recording unit in which the angle correction amount corresponding to the magnetic field intensity or the angle signal correction amount is recorded;
The angle is a value corrected by the correction amount obtained from the table recording unit based on the intensity signal.
Magnetic sensor. A magnetic sensor that includes a first sensor unit, a second sensor unit, an angle calculation unit, and an attachment position analysis unit, and detects a direction of a magnetic field to be measured,
The first sensor unit includes one or more magnetoresistance effect elements that are saturated with magnetization by the magnetic field, and outputs an angle signal corresponding to the direction of the magnetic field,
The angle calculation unit calculates an angle based on the angle signal,
The second sensor unit includes one or more magnetoresistance effect elements that are not magnetized and saturated with the magnetic field, and outputs an intensity signal corresponding to the intensity of the magnetic field,
The mounting position analysis unit includes a magnetic force distribution recording unit that records the direction of the magnetic field and the spatial distribution of the intensity, and specifies a position in the space from the angle and the intensity signal based on the spatial distribution.
Magnetic sensor. The magnetic sensor according to claim 4,
The position analysis unit detects an error of the specified position with respect to a reference position where the error of the angle calculated by the angle detection unit is minimized;
Magnetic sensor. A magnetic sensor according to any one of claims 1 to 5,
The one or more magnetoresistive elements of the second sensor section have shape anisotropy in the magnetization direction of the pinned layer;
Magnetic sensor. A magnetic sensor according to any one of claims 1 to 5,
The one or more magnetoresistive effect elements of the second sensor portion have a thick free layer compared to the one or more magnetoresistive effect elements of the first sensor portion.
Magnetic sensor. A magnetic sensor according to any one of claims 1 to 5,
The one or more magnetoresistive effect elements of the first sensor unit are sandwiched between soft magnetic materials having a yoke function so that magnetization is saturated by the magnetic field.
Magnetic sensor. A magnetic sensor according to any one of claims 1 to 5,
The one or more magnetoresistive elements of the second sensor section are shielded by a soft magnetic film so as not to saturate magnetization by the magnetic field;
Magnetic sensor.

Images