JP2006317203A - Sensor module, and angle detector using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angle detector capable of enhancing detection precision of a rotation angle, by making proper a fixed magnetization direction of a pin layer constituting a magnetoresistance element, in particular, in a fundamental state such as a completely stopped state and an idling state. <P>SOLUTION: All the magnetization directions of the pin layers in the plurality of magnetoresistance elements G1-G8 are inclined by 45° from a direction of an external magnetic field H crossed with axis O of a throttle valve shaft 4, under the completely stopped state where an engine is stopped and the idling state where the engine is operated but an automobile is stopped 8 (those are called as the fundamental state). A phenomenon that the magnetization of the each pin layer is fluctuated under the fundamental state by the external magnetic field H is prevented thereby to manufacture a throttle position sensor of excellent detection precision. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sensor module used for, for example, a throttle position sensor and the like, and in particular in a basic state such as an idling state, the rotational angle detection accuracy is improved by optimizing the fixed magnetization direction of the pinned layer constituting the magnetoresistive element. The present invention relates to a sensor module that can be improved and an angle detection device using the same.

  Patent Documents 1 and 2 below disclose inventions related to a throttle position sensor. In Patent Document 1, a Hall element is used as an element for detecting the rotation angle of a rotating body. On the other hand, in Patent Document 2, a ferromagnetic magnetoresistive element is used. Patent Document 2 does not describe the structure of the ferromagnetic magnetoresistive element in detail.

Since both Patent Documents 1 and 2 are non-contact type throttle position sensors, there is no sliding portion unlike a contact type throttle position sensor, and it is expected that durability and the like can be improved.
Japanese Patent No. 2546096 JP-A-5-322510

  By the way, when a non-contact type throttle position sensor is used, a magnet for applying a rotating magnetic field to the rotation angle detecting element is attached to the rotating body facing the rotation angle detecting element such as a magnetoresistive effect element. Yes.

  In a throttle position sensor used as a part of an electronic fuel injection device such as an automobile, when a driver steps on an accelerator pedal, the throttle valve opens in conjunction with it, and the amount of air flowing into the cylinder increases. The throttle position sensor linked to the throttle valve detects the opening / closing angle of the throttle valve, and sends data indicating the opening / closing angle to the control device. The control device analyzes and feeds back a large number of data including this data, thereby adjusting the opening / closing angle of the throttle valve so that an appropriate amount of air is always sent to the cylinder.

  When the driver is stepping on the accelerator pedal as described above, it is while the vehicle is running, and the time that the driver is stepping on the accelerator pedal is not so long in the day. That is, most of the time is when the engine of the automobile is turned off (completely stopped state) or when the engine is running but the accelerator pedal is not depressed while the automobile is stopped (idling state). In the complete stop state and the idling state (hereinafter, these two states are referred to as a basic state), the throttle valve is in a closed state. The external magnetic field from the magnet continues to be applied.

  The rotation angle detecting element has, for example, a four-layer structure of an antiferromagnetic layer, a pinned layer, a nonmagnetic material layer, and a free layer as a basic structure. When a spin valve thin film element with variable resistance is used, the external magnetic field is always applied to the pinned layer and the free layer even in the basic state. At this time, the magnetization of the pinned layer should not fluctuate under the influence of the external magnetic field, but since the external magnetic field continues to be applied from the same direction for a long time, the magnetization of the pinned layer fluctuates by the external magnetic field, The phenomenon that the magnetization of the pinned layer follows the direction of the external magnetic field is likely to occur. Such a phenomenon remarkably occurred particularly when used at a high temperature. This is because the fixed magnetization intensity of the pinned layer is reduced by reducing the exchange coupling magnetic field generated between the antiferromagnetic layer and the pinned layer. As described above, the magnetization direction of the pinned layer fluctuates, so that the detection accuracy of the rotation angle in the throttle position sensor is lowered.

  In both Patent Documents 1 and 2, a plurality of rotation angle detection elements are provided. If the number of rotation angle detection elements is one, the output voltage is too small or it is difficult to perform accurate angle detection due to waveform distortion. Therefore, the detection accuracy can be improved by providing a plurality of rotation angle detection elements. Has been done. However, when a plurality of the rotation angle detection elements are provided as described above, it is necessary to reduce the influence of the external magnetic field on all the pin layers in the same manner.

  Accordingly, the present invention solves the above-described conventional problems, and in particular, in a basic state such as a complete stop state and an idling state, the rotation angle is optimized by optimizing the fixed magnetization direction of the pinned layer constituting the magnetoresistive element. An object of the present invention is to provide an angle detection device capable of improving the detection accuracy of the above.

The present invention is a sensor module comprising at least two or more magnetoresistive elements for rotating together with a drive shaft and detecting a rotation angle of a rotating body to which a magnet is attached,
The magnetoresistive element includes at least a pinned layer whose magnetization direction is fixed in one direction, a free layer that faces the pinned layer via a nonmagnetic material layer and receives an external magnetic field from the magnet, and changes in magnetization direction Have
In the basic state, the magnetization direction of each pinned layer is characterized by being inclined by 45 degrees with respect to the direction of the external magnetic field intersecting the axis of the drive shaft.

  The basic state usually means the posture state that is the longest in time. In the present invention, in such a basic state, the magnetization direction of each pinned layer of the plurality of magnetoresistive elements and the direction of the external magnetic field from the magnet are shifted by 45 degrees, so that the external magnetic field in all the pinned layers is Thus, the phenomenon in which the magnetization of the pinned layer fluctuates due to the influence of the external magnetic field can be similarly suppressed in all the pinned layers, and the detection accuracy can be improved as compared with the conventional case.

  The present invention further includes a first magnetoresistive element for generating a SIN signal and a second magnetoresistive element for generating a COS signal, the first magnetoresistive element of the first magnetoresistive element The magnetization direction of the pinned layer is preferably orthogonal to the magnetization direction of the pinned layer of the second magnetoresistive effect element. Thereby, detection accuracy can be improved more.

  The sensor module may be further equipped with the magnet.

  The angle detection device according to the present invention includes the above-described sensor module (without magnets) and the magnet and the rotating body, or includes the above-described sensor module (with magnets) and the rotating body. It is characterized by.

  The angle detection device is used for in-vehicle use, and the basic state refers to a state where the engine is turned off and an idling state.

  The angle detection device is, for example, a throttle position sensor for detecting an opening / closing angle of a throttle valve, or an accelerator position sensor for detecting an accelerator amount of an accelerator pedal from a rotation angle of the rotating body. .

  In the present invention, in the basic state, the magnetization direction of each pinned layer of the plurality of magnetoresistive elements is inclined by 45 degrees with respect to the direction of the external magnetic field from the magnet, so that The influence can be uniformly weakened, and the phenomenon that the magnetization of the pinned layer fluctuates due to the influence of the external magnetic field can be similarly suppressed in all the pinned layers, so that the detection accuracy can be improved as compared with the conventional case.

  FIG. 1 is a schematic configuration diagram (partial cross-sectional view) for explaining an in-vehicle sensor provided with a throttle position sensor according to the present embodiment, and FIG. 2 shows a relationship between a magnet and a magnetoresistive effect element in a basic state. 3 is a partial plan view of the throttle position sensor, FIG. 3 is a block configuration diagram showing the configuration of the throttle position sensor in FIG. 2, and FIG. 4a is a different form from FIG. FIG. 4B is a block diagram of the throttle position sensor shown in FIG. 4A, and FIG. 5 is a partial side view of the accelerator module provided with the accelerator position sensor of the present embodiment. It is. In the plan views of FIGS. 2 and 4a, the rotary plate 20, the mounting plate 18 and the like constituting the throttle position sensor 10 are omitted in the drawing, and only the positional relationship between the magnet 24 and the substrate 21 to which the magnetoresistive effect element is attached. Is shown from directly above.

  In the figure, the Z1-Z2 direction indicates the height direction. The X1-X2 direction indicates the width direction, the Y1-Y2 direction indicates the length direction, and one direction has a relationship orthogonal to the remaining two directions.

  The in-vehicle sensor 1 shown in FIG. 1 is shown in a cross-sectional view cut from a plane direction parallel to a plane composed of two directions of the Z1-Z2 direction and the X1-X2 direction, except for the throttle valve 3. The throttle valve 3 and the accelerator 5 are shown in partial side views.

  The on-vehicle sensor 1 includes a throttle valve 3, an intake passage 2, and a throttle position sensor 10. The vehicle-mounted sensor 1 constitutes a part of an electronic fuel injection device.

  As shown in FIG. 1, the in-vehicle sensor 1 is provided with a disk-like throttle valve 3 in an intake passage 2 between an intake port (not shown) and the engine. The throttle valve 3 adjusts the flow rate of air flowing into the engine.

  The throttle valve 3 is rotatably supported with respect to a drive shaft (throttle valve shaft) 4. The diameter of the throttle valve 3 is slightly smaller than the intake passage 2. The throttle valve 3 is in a fully open state when the surface of the throttle valve 3 is parallel to the air inflow direction (arrow direction shown in the figure), and is in a posture perpendicular to the air inflow direction. However, the throttle valve 3 is fully closed.

  A link member (not shown) is provided at one end (end in the Z1 direction) of the throttle valve shaft, and the link member and the lever portion 6 of the accelerator 5 are connected by a wire (not shown). . A biasing member (not shown) is attached to the other end (end in the Z2 direction) of the throttle valve shaft, and the throttle valve shaft moves the biasing member in the direction of closing the throttle valve 3. It is energized by. When the accelerator pedal 7 of the accelerator 5 is depressed, the wire is pulled against the urging direction of the urging member in conjunction with this, and the throttle valve shaft can be rotated to open the throttle valve 3. It is said that.

  The throttle position sensor 10 is provided with, for example, a disk-shaped rotating plate 20, and a through hole 20 a for inserting the throttle valve shaft 4 is provided at the center of the upper surface of the rotating plate 20. Since the rotating plate 20 is attached to the throttle valve shaft 4, the rotating plate 20 rotates together with the rotation of the throttle valve shaft 4. The throttle valve shaft 4 is supplied with a driving force from a driving unit 19 composed of a gear or the like. The throttle position sensor 10 is provided with a substrate (fixing member) 21 at a position facing the rotary plate 20 in the height direction (Z1-Z2 direction in the drawing). Resistance effect elements G1 to G8 are provided (sensor module). The planar shape of the substrate 21 is, for example, a quadrangular shape as shown in FIG. 2a, and a CPU that calculates the opening / closing angle of the throttle valve 3 from the voltage change from the magnetoresistive element on the back surface 21b of the substrate 21. A semiconductor device (not shown) such as a memory is mounted.

  As shown in FIG. 1, the substrate 21 is provided in a lower housing 10 b that constitutes an outer frame of the throttle position sensor 10. The lower housing 10b is formed in a concave shape, and the substrate 21 is attached to the surface in the concave portion. The lower housing 10b is provided with a plate-like attachment plate 18 for attaching the rotating plate 20 above the substrate 21 (in the Z1 direction in the drawing) provided in the lower housing 10b. A mounting portion 20 d of the rotating plate 20 is mounted in a through hole provided in the mounting plate 18, and the rotating plate 20 is rotatably supported by the mounting plate 18. The center of the through hole formed in the mounting plate 18 coincides with the axis O of the throttle valve shaft 4 in the height direction (Z1-Z2 direction in the drawing). As described above, the lower housing 10 b provided with the substrate 21 having the magnetoresistive effect element is engaged with the upper housing 10 a constituting the outer frame of the throttle position sensor 10.

  As shown in FIG. 1, the rotating plate 20 and the substrate 21 face each other in the height direction (Z direction in the drawing), and the rotating plate 20 and the substrate 21 are separated from each other by a predetermined distance. As shown in FIG. 1, a ring-shaped magnet 24 is attached to the outer periphery of the rotating plate 20. For example, as shown in FIG. 2, the magnet 24 has a ring shape when viewed from a plane (XY plane). The magnet 24 is not limited to a ring shape. For example, the shape may be a shape other than a hollow shape such as a rectangle. For example, the magnet 24 may be attached to the lower surface of the rotating plate 20 (the surface facing the substrate 21). A plurality of the magnets 24 may be provided.

  As shown in FIG. 2, eight magnetoresistive elements G <b> 1 to G <b> 8 are provided on the surface 21 a of the substrate 21 at a position facing the rotating plate 20 in the height direction (Z direction in the drawing).

  The magnetoresistive elements G1 to G8 have a structure called a spin valve thin film element, and the basic film structure is a structure in which an antiferromagnetic layer, a pin layer, a nonmagnetic material layer, and a free layer are stacked. The antiferromagnetic layer is formed of an antiferromagnetic material such as an IrMn alloy or a PtMn alloy. The pinned layer is formed of a ferromagnetic material such as a CoFe alloy. The nonmagnetic material layer is formed of a nonmagnetic material such as Cu. The free layer is formed of a soft magnetic material such as a NiFe alloy. The antiferromagnetic layer and the pinned layer are formed in contact with each other, and an exchange coupling magnetic field (Hex) is generated at the interface between the antiferromagnetic layer and the pinned layer by heat treatment, and the magnetization of the pinned layer is fixed in a predetermined direction.

  As shown in FIG. 2, the pin layers of the magnetoresistive elements G1 and G4 are in the X2 direction, the pin layers of the magnetoresistive elements G2 and G3 are in the X1 direction, and the pin layers of the magnetoresistive elements G5 and G8 are In the Y1 direction shown in the figure, the pinned layers of the magnetoresistive elements G6 and G7 are fixed in magnetization in the Y2 direction shown. The magnetization of the free layer is aligned in one direction by a bias magnetic field from a bias layer (not shown). The magnetizations of the free layers of the magnetoresistive elements G1 to G8 are aligned in the direction orthogonal to the magnetization direction of the pinned layers of the magnetoresistive elements G1 to G8. The magnetization of the free layer is not as strongly magnetized as the pinned layer, so that the magnetization can be easily changed under the influence of an external magnetic field. In addition, the spin valve thin film elements G1 to G8 are mainly formed with an electrode layer for passing a current through three layers of a pinned layer, a nonmagnetic material layer, and a free layer. The magnetoresistive elements G1 to G8 may be spin valve thin film elements in which the antiferromagnetic layer is not formed. In such a spin valve thin film element, the magnetization of the pinned layer is fixed by the uniaxial anisotropy of the pinned layer itself. The above-described configuration of the spin-valve type thin film element is only an example, and a spin-valve type thin-film element formed with a configuration other than the above may naturally be used.

  As shown in FIG. 3, the throttle position sensor 10 includes a sensor unit 11 and a signal processing unit 12 that processes an output signal output from the sensor unit 11. The left side of the alternate long and short dash line in FIG. 3 indicates the sensor unit 11, and the right side indicates the signal processing unit 12.

  Each of the magnetoresistive effect elements G1 to G8 forms a group A1 (hereinafter, referred to as a first magnetoresistive effect element group A1) as the first magnetoresistive effect element G1 to G4. The bridge circuit WB1 is configured. Further, the magnetoresistive effect elements G5 to G8 form a group A2 (hereinafter referred to as a second magnetoresistive effect element group A2) as the second magnetoresistive effect element, and constitute the second bridge circuit WB2. . The first bridge circuit WB1 includes a circuit in which the magnetoresistive effect element G1 and the magnetoresistive effect element G2 are connected in series, and a circuit in which the magnetoresistive effect element G3 and the magnetoresistive effect element G4 are connected in series. Are connected in parallel. Similarly, the second bridge circuit WB2 includes a circuit in which the magnetoresistive effect element G5 and the magnetoresistive effect element G6 are connected in series, and a circuit in which the magnetoresistive effect element G7 and the magnetoresistive effect element G8 are connected in series. Are connected in parallel.

  One end of the first bridge circuit WB1 and the second bridge circuit WB2 connected in parallel is connected to the power source Vcc, and the other end is grounded to the ground GND.

  When the driver depresses the accelerator pedal 7 and the throttle valve 4 is opened, the rotating body 20 rotates, and thereby the free layer forming the magnetoresistive effect elements G1 to G8 by the rotating magnetic field from the magnet 24. The direction of magnetization is changed. Thereby, the resistance values of the magnetoresistive elements G1 to G8 change according to the angle formed by the magnetization direction of the free layer and the magnetization direction of the pinned layer. Therefore, the phases of the magnetoresistive effect element G1 and the magnetoresistive effect element G2 constituting the first bridge circuit WB1 and the magnetoresistive effect element G3 and the magnetoresistive effect element G4 are mutually shifted in phase. Two sinusoidal signals that are 180 degrees apart are output. At the same time, the phases of the magnetoresistive effect element G5 and the magnetoresistive effect element G6 and the connection part of the magnetoresistive effect element G7 and G8 constituting the second bridge circuit are 180. Two signals with different sine waves are output.

  At this time, since the magnetization direction of the pinned layers of the magnetoresistive effect elements G1 to G4 and the magnetization direction of the pinned layers of the magnetoresistive effect elements G5 to G8 are orthogonal to each other, 2 is output from the first bridge circuit WB1. If two signals are a + sin signal and a −sin signal, the two signals output from the second bridge circuit WB2 are a + cos signal and a −cos signal.

  As shown in this embodiment, when a sinusoidal signal output from a connection portion between the magnetoresistive effect element G3 and the magnetoresistive effect element G4 of the first bridge circuit WB1 is a + sin signal, the magnetoresistive effect element A -sin signal is output from the connection between G1 and the magnetoresistive element G2. In addition, a + cos signal is output from a connection portion between the magnetoresistive effect element G5 and the magnetoresistive effect element G6 of the second bridge circuit WB2, and a connection portion between the magnetoresistive effect element G7 and the magnetoresistive effect element G8 is −. A cos signal is output.

  The signal processing unit 12 mainly includes a control unit 15, a first signal conversion unit 12 </ b> A and a second signal conversion unit 12 </ b> B, a signal adjustment unit 13, and a first function calculation unit 14.

  The control means 15 includes a semiconductor device such as a CPU and a memory means, and has a function of supervising a series of signal processing in the signal adjustment means 13, the first function calculation means 14, and the like. The first signal converting means 12A generates a SIN signal by taking the difference between the two types of + sin signal and −sin signal output from the first bridge circuit WB1, and outputs the amplified signal as A It has a function of converting to digital data by / D conversion. Similarly, the second signal conversion unit 12B generates a COS signal by taking the difference between the two types of + cos signal and −cos signal output from the first bridge circuit WB1, and also outputs an amplified signal. Has a function of A / D converting the signal into a digital data signal.

  Here, for example, A1, A2, B1 and B2 are amplitude coefficients, a1, a2, b1 and b2 are offset coefficients, the + sin signal is + A1 · sin θ + a1, the −sin signal is −A2 · sin θ−a2, and the + cos signal. Is expressed as + B1 · cos θ + b1 and the −cos signal is expressed as −B2 · cos θ−b2, the SIN signal generated by the first signal converting means 12A is (+ A1 · sin θ + a1) − (− A2 · sin θ−a2). ) = (A1 + A2) · sin θ + (a1 + a2). Similarly, the COS signal generated by the second signal converting means 12B is (+ B1 · cos θ + b1) − (− B2 · cos θ−b2) = (B1 + B2) · cos θ + (b1 + b2).

  The signal adjusting means 13 has a function of performing offset adjustment and gain adjustment of the SIN signal and the COS signal, and matching the reference (0 point) and amount (amplitude amount) of the amplitude direction of both signals. That is, in the above example, the gain adjustment means that the amplitude coefficient of the SIN signal and the COS signal is set to the same value by setting A1 + A2 = B1 + B2, and the offset adjustment means that a1 + a2 = b1 + b2 = 0. This means that the deviation of the amplitude reference from the origin position (0 point) is eliminated.

The first function calculation means 14 is software for calculating function values such as sin, cos, tan, tan ⁻¹ = arctan, sinh, cosh, exp, log, for example, a well-known CORDIC (Coordinate Rotation Digital Computer) algorithm. The TAN process for calculating the tangent value (tan = SIN signal / COS signal) by dividing the digital data of the SIN signal by the digital data of the COS signal, Atan processing for calculating a rotation angle φ of the rotating plate 20 by calculating an arctangent value (arctan (SIN signal / COS signal)) from a value obtained by the TAN processing.

  FIG. 2 shows the magnetization direction of the magnet 24 in the basic state of the throttle position sensor 10. As shown in FIG. 2, the magnet 24 has an N pole on the upper left side and an S pole on the lower right side in the figure, and the external magnetic field H is inclined 45 degrees with respect to both the X1 direction and the Y2 direction. Has arisen in the direction.

  As described above, each pinned layer of the magnetoresistive effect elements G1 to G8 is fixed in magnetization in the direction parallel to the illustrated X1-X2 direction or in the direction parallel to the illustrated Y1-Y2 direction. The magnetization direction of each pinned layer and the direction of the external magnetic field H have a 45 degree relationship.

  First, the “basic state” will be described. The “basic state” in this embodiment means both the state where the engine of the automobile is turned off (completely stopped state) and the state where the engine is running but the automobile is stopped (idling state). ing. In both of these states, the throttle valve 4 is closed because the driver has not depressed the accelerator pedal 7. Here, normally, when the accelerator pedal 7 is depressed from the idling state, the throttle valve 4 is smoothly opened in conjunction with it. Strictly speaking, since the valve 4 is in an open state, it is not in a completely closed state, but in this embodiment, the state of the throttle valve 4 in the completely stopped state and the idling state is “closed state”. ". Further, when the throttle valve 4 is in a different state between the complete stop state and the idling state, for example, the opening / closing angle of the throttle valve 4 in the idling state is larger than the opening / closing angle of the throttle valve 4 in the complete stop state. If there is a difference, either the complete stop state or the idling state is determined as the basic state, or the opening / closing angle of the throttle valve 4 in the complete stop state and the throttle valve 4 in the idling state An opening / closing angle in the middle of the opening / closing angle can be determined as the basic state.

  Next, the external magnetic field H will be considered. As shown in FIG. 2, the N pole and S pole of the magnet 24 and the axis O of the throttle valve shaft 4 are on the lines inclined 45 degrees from the X2 direction and the Y1 direction, respectively. The external magnetic field H (or may be expressed as magnetic lines of force) intersecting with each other is generated in linear directions inclined 45 degrees from the X2 direction and the Y1 direction, respectively. By the way, considering the direction of any external magnetic field generated from the magnet 24, the direction of the external magnetic field varies depending on the location. For example, an external magnetic field that does not intersect the axis O shown in FIG. 2 (an external magnetic field generated at a position away from the axis O in the Y1-Y2 direction, etc.) is generated in a curved line and is inclined by 45 degrees from the X2 direction and the Y1 direction, respectively. Not facing the straight line direction. In this embodiment, in the basic state, the magnetization direction of each pinned layer and the direction of the external magnetic field H are shifted by 45 degrees. However, as described above, the direction of the external magnetic field is linear depending on the location. When the magnet 24 and the magnetoresistive elements G1 to G8 are viewed from directly above, a linear external magnetic field H intersecting the axis O of the throttle valve shaft 4 is applied. The reference direction in the basic state is used, and in the basic state, the direction of the external magnetic field H in the reference direction and the magnetization direction of the pinned layer 22 are shifted by 45 degrees. Alternatively, even if it is defined that the linear direction passing through the N pole of the magnet 24, the axis O, and the S pole of the magnet 24 and the magnetization direction of the pinned layer 22 are shifted by 45 degrees, it is the same.

  The magnetoresistive elements G1 to G4 in which the magnetization of the pinned layer is fixed in a direction parallel to the illustrated X1-X2 direction, and the magnetism in which the magnetization of the pinned layer is fixed in a direction parallel to the illustrated Y1-Y2 direction. It is preferable that the resistance effect elements G5 to G8 have a point-symmetrical relationship with the axis O as the axis of symmetry. The magnetoresistive effect element G1 and the magnetoresistive effect element G8 are point-symmetric with respect to the axis O, and the magnetoresistive effect element G1 and the magnetoresistive effect element G8 are point-symmetric with respect to the axis O. The magnetoresistive effect element G2 and the magnetoresistive effect element G6 are point-symmetric with respect to the axis O, and the magnetoresistive effect element G3 and the magnetoresistive effect element G7 have the axis O about the axis of symmetry. The magnetoresistive effect element G4 and the magnetoresistive effect element G5 are in point symmetry with the axis O as the axis of symmetry. Thereby, the influence of the external magnetic field H on the first magnetoresistive element group A1 and the second magnetoresistive element group A2 can be made substantially the same.

  As described above, in the basic state, by setting the magnetization direction A of each pinned layer to be inclined by 45 degrees from the direction of the external magnetic field H, the influence of the external magnetic field H on each pinned layer is similarly weakened. Therefore, the phenomenon that the fixed magnetization of the pinned layer fluctuates due to the external magnetic field H can be appropriately suppressed. Therefore, in the present embodiment, the detection accuracy of the throttle position sensor 10 can be accurately maintained.

  In the embodiment of FIG. 2, the magnetization direction of each pinned layer is not the same as the direction of the external magnetic field H. Therefore, in the basic state, the magnetization of each pinned layer may be slightly fluctuated due to the influence of the external magnetic field H. There is. However, for example, when the magnetization of the pinned layer is directed in a direction orthogonal to the external magnetic field H, the influence of the external magnetic field H on the pinned layer is the strongest, and the magnetization of the pinned layer is in the direction of the external magnetic field H. Then, there is a risk of tilting up to 90 degrees from a predetermined direction. In the embodiment shown in FIG. 2, since there are a plurality of magnetoresistive elements G1 to G8, and not all the pinned layers are magnetized in the same direction, the magnetization direction of all the pinned layers is in the same direction. The magnetization cannot be controlled so that the external magnetic field H is applied. On the other hand, for example, when the external magnetic field H is applied in a direction parallel to the X1-X2 direction, the pinned layers of the magnetoresistive elements G1 to G4 can maintain the predetermined magnetization direction appropriately, but the pins of the magnetoresistive elements G5 to G8 Since the magnetization direction of the layer is orthogonal to the direction of the external magnetic field H, the magnetization of the pinned layers of the magnetoresistive elements G5 to G8 is aligned with the direction of the external magnetic field H, and from the Y1-Y2 direction. The possibility of tilting in the X1-X2 direction is increased. Then, as described above, the first bridge circuit WB1 is formed by the four magnetoresistive elements G1 to G4 constituting the first magnetoresistive element group A1, and the output signal (+ sin) is generated from the first bridge circuit WB1. Signal, -sin signal), a second bridge circuit WB2 is formed by the four magnetoresistive elements G5 to G8 constituting the second magnetoresistive element group A2, and an output signal is output from the second bridge circuit WB2. When (+ COS signal, -COS signal) is taken out, the + COS signal and -COS signal have a larger waveform distortion (error signal) than that of the + sin signal and -sin signal, which makes the throttle valve accurate. The open / close angle of 4 cannot be detected. On the other hand, when the magnetization directions of all the pinned layers are inclined 45 degrees from the direction of the external magnetic field H as in the embodiment of FIG. 2, only a specific pinned layer is very strong and is affected by the external magnetic field H. Accordingly, the phenomenon that the direction of the external magnetic field H is made can be avoided, and the influence of the external magnetic field H can be similarly reduced for all the pinned layers. For this reason, the phenomenon that the magnetization of the pinned layer fluctuates due to the external magnetic field H can be appropriately suppressed, and therefore the opening / closing angle of the throttle valve 4 can be detected with high accuracy.

  FIG. 4a is an alternative embodiment to FIG. In FIG. 4 a, two magnetoresistive elements 40 and 41 are provided on the substrate 21. The element structure of the magnetoresistive effect elements 40 and 41 is not different from the magnetoresistive effect elements G1 to G8 of FIG. 2, so please refer to that.

  The magnetization direction D of the pinned layer of the magnetoresistive effect element 40 is oriented in the X2 direction shown in the figure, and the magnetization direction E of the pinned layer of the magnetoresistive effect element 41 is oriented in the X1 direction shown in the figure, The magnetization directions D and E are in an antiparallel state.

  In the basic state, the magnetoresistive elements 40 and 41 in FIG. 4 a are inclined 45 degrees with respect to the direction of the external magnetic field H generated from the magnet 24 in the basic state. . For this reason, the influence of the external magnetic field H on each pinned layer of the magnetoresistive effect elements 40 and 41 can be similarly reduced, and the magnetization of the pinned layer fluctuates due to the influence of the external magnetic field from the magnet 24. The phenomenon can be appropriately suppressed. As shown in FIG. 4 b, the magnetoresistive elements 40 and 41 are connected in series. For example, a power supply Vcc is connected to the magnetoresistive element 41 and a ground GND is connected to the magnetoresistive element 40. A voltage is output from a connection portion between the magnetoresistive effect element 40 and the magnetoresistive effect element 41, and the opening / closing angle of the throttle valve 4 is controlled by a control unit configured by the semiconductor device 23 based on the voltage value. Detected.

  When the driver depresses the accelerator pedal 7 and the throttle valve 4 is opened, the rotating body 20 rotates, whereby the rotating external magnetic field from the magnet 24 causes the free layers of the magnetoresistive effect elements 40 and 41 to rotate. The magnetization direction varies, and the resistance value changes based on the relationship between the fixed magnetization direction of the pinned layer and the magnetization direction of the free layer of the magnetoresistive effect elements 40 and 41. As a result, the voltage value output from the connecting portion between the magnetoresistive effect element 40 and the magnetoresistive effect element 41 varies, and the opening / closing angle of the throttle valve 4 is detected based on the voltage change by the control. The In FIG. 4B, since the magnetization directions D and E of the pinned layers of the magnetoresistive effect elements 40 and 41 are opposite to each other, the resistance change of the magnetoresistive effect element 40 and the resistance change of the magnetoresistive effect element 41 are in opposite phases. (The phase is 180 ° different), so that when the resistance value of the magnetoresistive effect element 40 is minimized, the resistance value of the magnetoresistive effect element 41 is maximized, and the resistance value of the magnetoresistive effect element 40 is maximized. Then, the resistance value of the magnetoresistive effect element 41 has a minimum relationship. Therefore, a large resistance change can be obtained as compared with the case where only one magnetoresistance effect element is provided, and the opening / closing angle of the throttle valve 4 can be detected with high accuracy by the control unit.

  As shown in FIG. 4a, it is preferable that the distance L1 from the axis O to the magnetoresistive element 40 and the distance L2 from the axis O to the magnetoresistive element 41 are the same. In addition, the center F of the magnetoresistive element 40 where the center line in the width direction (X1-X2 direction in the drawing) of the magnetoresistive effect element 40 and the center line in the length direction (Y1-Y2 direction in the drawing) intersect, It is preferable that the center G of the magnetoresistive effect element 41 at which the center line in the width direction of the magnetoresistive effect element 41 intersects the center line in the length direction is point symmetric with respect to the axis O as an axis of symmetry in the basic state. . Thereby, the influence of the external magnetic field on the magnetoresistive effect elements 40 and 41 can be made the same, and the detection accuracy can be improved.

  Incidentally, as shown in FIG. 1, the throttle position sensor 10 in the present embodiment is configured to include all of these components such as a substrate 21, a magnetoresistive effect element, a magnet 24, and a rotating plate 20. Here, whether or not the throttle valve shaft 4 is a component of the throttle position sensor 10 is arbitrary. Further, when the substrate 21 having the magnetoresistive element and the lower housing 10b including the substrate 21 are manufactured and sold as a sensor module, whether or not the magnet 24 is set and sold in the sensor module. Is optional. When the magnet 24 is not sold as a set in the sensor module, when a set manufacturer who has purchased the sensor module actually uses the sensor module for the throttle position sensor 10, the magnet 24 is installed in the throttle position sensor 10 later. Will be attached. At this time, it is necessary to attach the magnet 24 so that the external magnetic field H generated from the magnet 24 in the basic state and the magnetization direction of the pinned layer of the magnetoresistive element are inclined by 45 degrees. At this time, since the magnetization direction of the pinned layer cannot be seen, the attachment method of the magnet 24 (whether the N pole or the S pole is placed on the side) is displayed in advance, for example, the visible position of the sensor module. It is preferable to display such as “N pole side” and “S pole side”.

  The structure of the throttle position sensor 10 may be used as an accelerator position sensor 50 at the end of the lever 6 of the accelerator 5 opposite to the accelerator pedal 7 (FIG. 5). The accelerator position sensor 50 is for detecting the amount of accelerator when the driver steps on the accelerator pedal 7. When the accelerator pedal is depressed and the lever 6 is pressed, the accelerator position sensor 50 The provided rotating body rotates. At this time, as in the case of FIG. 1, the external magnetic field H from the magnet 24 becomes a rotating magnetic field, and the magnetization direction of the free layer constituting the magnetoresistive effect element varies with the rotating magnetic field. A resistance change based on the magnetization direction of the free magnetic layer and the fixed magnetization direction of the pinned magnetic layer is regarded as a voltage change, thereby detecting how much the rotating body has rotated, and from there, the accelerator pedal 7 Detect accelerator amount. The basic state in the accelerator position sensor 50 is not different from the basic state in the throttle position sensor 10. That is, the basic state in the accelerator position sensor 50 means both a state where the automobile engine is turned off (completely stopped state) and a state where the engine is running but the automobile is stopped (idle state). Yes. In both of these states, the driver does not depress the accelerator pedal 7 (the feet may be on the pedal 7). 2 and 4, the embodiment shown in FIG. 5 also has a relationship in which the magnetization directions of all the pinned layers of the plurality of magnetoresistive elements are inclined 45 degrees from the direction of the external magnetic field H in the basic state. By doing so, it is possible to appropriately reduce the phenomenon that the magnetization of each pinned layer fluctuates under the influence of the external magnetic field H in the basic state, and it is possible to provide the accelerator position sensor 50 with excellent detection accuracy. become.

  The angle detection device having the same structure as the throttle position sensor 10 in the present embodiment may be used as a form other than the throttle position sensor 10 and the accelerator position sensor 50. In particular, when used for in-vehicle use, the basic state refers to the complete stop state and the idling state. When the angle detection device is used for purposes other than on-vehicle use, the basic state is usually defined as the posture state that is the longest in terms of time.

Schematic configuration diagram (partial sectional view) for explaining an in-vehicle sensor provided with a throttle position sensor of the present embodiment, A partial plan view of the throttle position sensor showing a relationship between a magnet and a magnetoresistive effect element in a basic state, The block block diagram which shows the structure of the throttle position sensor in FIG. FIG. 2 is a partial plan view of the throttle position sensor, showing a relationship between the magnet and the magnetoresistive element in a basic state, which is different from FIG. Block diagram of the throttle position sensor shown in FIG. The partial side view of the accelerator module provided with the accelerator position sensor of this Embodiment,

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 In-vehicle sensor 3 Throttle valve 4 Throttle valve shaft 5 Accelerator 7 Accelerator pedal 10 Throttle position sensor 20 Rotary plate 21 Substrate 40, 41, G1-G8 Magnetoresistive element 24 Magnet 50 Accelerator position sensor O Axis center

Claims (7)

A sensor module comprising at least two or more magnetoresistive elements for rotating together with a drive shaft and detecting a rotation angle of a rotating body to which a magnet is attached,
The magnetoresistive element includes at least a pinned layer whose magnetization direction is fixed in one direction, a free layer that faces the pinned layer via a nonmagnetic material layer and receives an external magnetic field from the magnet, and changes in magnetization direction Have
In a basic state, the magnetization direction of each pinned layer is inclined 45 degrees with respect to the direction of the external magnetic field intersecting with the axis of the drive shaft.   A first magnetoresistive element for generating a SIN signal and a second magnetoresistive element for generating a COS signal, the magnetization direction of the pinned layer of the first magnetoresistive element The sensor module according to claim 1, wherein is perpendicular to the magnetization direction of the pinned layer of the second magnetoresistive element.   The sensor module according to claim 1, wherein the sensor module is further equipped with the magnet.   An angle detection comprising the sensor module according to claim 1 and the magnet and a rotating body, or the sensor module according to claim 3 and the rotating body. apparatus.   The angle detection device according to claim 4, wherein the angle detection device is used for in-vehicle use, and the basic state refers to a state where the engine is turned off and an idling state.   The angle detection device according to claim 4, wherein the angle detection device is a throttle position sensor for detecting an opening / closing angle of a throttle valve.   The angle detection device according to claim 4, wherein the angle detection device is an accelerator position sensor for detecting an accelerator amount of an accelerator pedal from a rotation angle of the rotating body.

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