JP7226624B2 - Rotation detector - Google Patents

Description

The disclosure herein relates to a rotation detection device.

A rotation detection device for detecting the rotation state of a magnetized rotor is known, as disclosed in Japanese Unexamined Patent Application Publication No. 2002-200012. The magnetized rotor has a magnetized surface in which N poles and S poles are alternately magnetized in the rotation direction at a magnetization pitch λ. The rotation detection device includes a sensor chip (substrate) having a detection surface orthogonal to the magnetized surface and a plurality of magnetoresistive elements formed on the detection surface and whose resistance values change as the magnetized rotor rotates. I have.

JP 2010-145166 A

The rotation detector increases the amplitude of the obtained signal by generating a differential signal from outputs of a plurality of elements. For example, in the case of two elements, if the center-to-center distance of the elements is made equal to the magnetization pitch λ, the output phase difference becomes 180° and the differential signal can be increased.

However, if the center-to-center distance cannot be made equal to the magnetization pitch λ due to the miniaturization of the rotation detection device, the differential signal will become small.

The present disclosure has been made in view of such problems, and an object thereof is to provide a rotation detection device capable of increasing a differential signal.

The present disclosure employs the following technical means to achieve the above object. It should be noted that the symbols in parentheses indicate the corresponding relationship with specific means described in the embodiment described later as one aspect, and do not limit the technical scope.

A rotation detection device that is one of the present disclosure includes:
A rotation detection device for detecting the rotation state of a magnetized rotor (10) having a magnetized surface (10 m) in which N and S poles are alternately magnetized in the direction of rotation with a magnetization pitch λ and a magnetization period α. There is
It has a detection surface (21d) orthogonal to the magnetized surface, and a plurality of magnetoresistive effect elements (210) formed on the detection surface and having resistance values that change as the magnetized rotor rotates. As elements, a first element (211), a second element (212) arranged so that the center-to-center distance β from the first element is less than the magnetization pitch λ , a third element (213), and a third element A sensor chip ( 21) and
at least one bias magnet (22) for applying a bias magnetic field to the plurality of magnetoresistive elements;
a first differential section (230) for generating a differential signal from the outputs of the first element and the second element;
A second differential section (231, 232, 233) that generates a differential signal from the outputs of the third element, the fourth element, and the fifth element,
The angle between the reference line (L1) parallel to the direction in which the sensor chip and the magnetized surface face each other and along the detection surface and the magnetic vector of the bias magnetic field acting on the first element is θ1, The angle between the magnetic vector of the bias magnetic field acting on the two elements and the magnetic vector is θ2, the angle between the reference line and the magnetic vector of the bias magnetic field acting on the third element is θ3, and the angle between the reference line and the bias magnetic field acting on the fourth element is θ3. Assuming that the angle with the magnetic vector is θ4 ,
In an environment where no magnetic field different from the bias magnetic field is applied, the magnetic vector acting on the first element is tilted toward the second element with respect to the reference line and θ1>0, and the magnetic vector acting on the second element is the reference. The bias magnet is tilted to the first element side with respect to the line so that θ2<0 and 2×{180°−(β/α)×360°}>(θ1−θ2)>0 is satisfied. The first element and the second element are arranged with respect to
In an environment where no magnetic field different from the bias magnetic field is applied, the magnetic vector acting on the third element is inclined toward the fourth element with respect to the reference line and θ3>0, and the magnetic vector acting on the fourth element is the reference. With respect to the line, the bias magnet is inclined to the third element side so that θ4<0 and 2×{360°−(γ/α)×360°}>(θ3−θ4)>0 is satisfied. A third element and a fourth element are arranged opposite to each other.

According to this rotation detecting device, in an environment where no magnetic field different from the bias magnetic field is applied, the first element and the second element are arranged at positions where the magnetic vector of the bias magnetic field parallel to the reference line acts. In comparison, the differential signal can be increased.

According to this rotation detecting device, the third element and the fourth element are arranged at positions where the magnetic vector of the bias magnetic field parallel to the reference line acts in an environment where no magnetic field different from the bias magnetic field is applied. In comparison, the differential signal can be increased.

FIG. 3 is a plan view showing the positional relationship between the rotation detection device of the first embodiment and a magnetized rotor; 2 is a cross-sectional view taken along line II-II of FIG. 1; FIG. 2 is an enlarged view of the periphery of the rotation detection device in FIG. 1; FIG. 4 is a circuit diagram showing a rotation detection device; FIG. It is a figure for demonstrating rotation direction discrimination|determination. FIG. 4 is a diagram showing the relationship between the rotational position and the direction of the magnetic vector of the rotor magnetic field; FIG. 10 is a diagram showing changes in the direction of the magnetic vector of the rotor magnetic field in one magnetization cycle; FIG. 4 is a diagram showing an example of the arrangement of bias magnets and elements; 9 is a diagram showing magnetic vectors acting on elements in the arrangement shown in FIG. 8. FIG. 9 is a diagram showing output waveforms of elements in the arrangement shown in FIG. 8. FIG. FIG. 10 is a diagram showing another example of the arrangement of bias magnets and elements; 12 is a diagram showing magnetic vectors acting on elements in the arrangement shown in FIG. 11; FIG. 12 is a diagram showing output waveforms of elements in the arrangement shown in FIG. 11; FIG. FIG. 4 is a diagram showing phases of signals; 4 is a diagram showing the relationship between the angle of the magnetic vector of the bias magnetic field and the phase of the signal at the rotational position P1. FIG. FIG. 4 is a diagram showing the positional relationship between a magnetized rotor and first and second elements; 3 is a diagram showing the relationship between the phase difference (θ1−θ2) due to the magnetic vector of the bias magnetic field and the amplitude of the differential signal S1. FIG. FIG. 4 is a diagram showing specific signal waveforms showing the effect of the magnetic vector of the bias magnetic field; FIG. 4 is a diagram showing a specific example of element arrangement with respect to a bias magnet; FIG. 4 is a diagram showing the positional relationship between a magnetized rotor and third, fourth, and fifth elements; 4 is a diagram showing waveforms of signals C, D, and E; FIG. FIG. 4 is a diagram showing waveforms of various signals when the phase difference between signals C and D is 0° to 180°; FIG. 4 is a diagram showing waveforms of various signals when the phase difference between signals C and D is 180°; FIG. 4 is a diagram showing waveforms of various signals when the phase difference between signals C and D is 180° to 360°; FIG. 4 is a diagram showing waveforms of various signals when the phase difference between signals C and D is 360°; 4 is a diagram showing the relationship between the phase difference (θ3−θ4) due to the magnetic vector of the bias magnetic field and the amplitude of the differential signal S2. FIG. FIG. 4 is a diagram showing specific signal waveforms showing the effect of the magnetic vector of the bias magnetic field; It is a figure which shows the influence of an external magnetic field. FIG. 10 is a diagram showing a high-sensitivity element and a low-sensitivity element used in the rotation detection device of the second embodiment; FIG. 4 is a diagram showing a specific example of element arrangement with respect to a bias magnet; FIG. 10 is a diagram showing a modification of the arrangement of elements with respect to the bias magnet; FIG. 10 is a diagram showing a modification of the arrangement of the rotation detection device with respect to the magnetized rotor;

A number of embodiments will be described with reference to the drawings. In several embodiments, functionally and/or structurally corresponding parts are provided with the same reference numerals. Hereinafter, the direction along the rotation axis of the magnetized rotor will be referred to as the Z1-Z2 direction, and one direction orthogonal to the Z1-Z2 direction will be referred to as the Y1-Y2 direction. A direction orthogonal to both the Z1-Z2 direction and the Y1-Y2 direction is indicated as the X1-X2 direction. Unless otherwise specified, the planar shape is defined by the X1-X2 direction and the Y1-Y2 direction.

(First embodiment)
First, based on FIGS. 1 to 5, the schematic configuration of the magnetized rotor and the rotation detection device will be described. FIG. 3 is an enlarged view of a portion of FIG. 1, specifically, the periphery of the rotation detection device. In FIG. 3, which is an enlarged view, the magnetized rotor is shown linearly for the sake of convenience. In FIG. 3, the sealing resin body is omitted for convenience. For the circuit configuration shown in FIG. 4, the description in Japanese Patent Application Laid-Open No. 2017-9411 can be used.

As shown in FIGS. 1 to 3, the magnetized rotor 10 rotates together with the rotating body to be fixed. The magnetized rotor 10 is fixed to a rotating body such as an engine crankshaft or an axle in a vehicle, for example. The magnetized rotor 10 has a magnetized surface 10m. In the present embodiment, the magnetized rotor 10 has a planar, substantially circular plate shape, and as shown in FIG. It is As shown in FIG. 3, on the magnetized surface 10m, the N pole 10n and the S pole 10s are alternately magnetized in the rotational direction with a magnetization pitch λ and a magnetization period α. Note that the magnetization period α=2×λ.

The rotation detection device 20 detects the rotation state of the magnetized rotor 10 . The rotation detection device 20 constitutes a rotation detection system together with the magnetized rotor 10 . The rotation detection device 20 is arranged facing the magnetized surface 10m with a predetermined gap. The rotation detection device 20 has a sensor chip 21 , a bias magnet 22 , a circuit chip 23 , a lead frame 24 and a sealing resin body 25 .

The lead frame 24 is arranged so that the plate thickness direction is substantially parallel to the Z1-Z2 direction. The sensor chip 21 and the circuit chip 23 are fixed on the same side of the lead frame 24 on the island 24a. A bias magnet 22 is fixed to the opposite side of the island 24a. The sensor chip 21 is electrically connected to the circuit chip 23 via bonding wires 26 . The circuit chip 23 is electrically connected to terminals 24 b to 24 d of the lead frame 24 via bonding wires 26 . The terminal 24b is a ground (GND) terminal and is connected to the island 24a. The terminal 24c is a terminal for power supply (Vcc), and the terminal 24d is a terminal for output (Vout).

The sealing resin body 25 integrally seals a part of the lead frame 24 including the sensor chip 21, the bias magnet 22, the circuit chip 23, and the island 24a. Sealing resin body 25 is formed using, for example, an epoxy resin. The sealing resin body 25 is molded by, for example, a transfer molding method. The terminals 24b to 24d extend in the Y2 direction and protrude from the sealing resin body 25 to the outside.

The sensor chip 21 is a semiconductor chip formed with a magnetoresistive effect element 210 whose resistance value changes as the magnetized rotor 10 rotates. The sensor chip 21, as shown in FIG. 3, has a detection surface 21d orthogonal to the magnetized surface 10m. A plurality of magnetoresistive elements 210 are formed on the detection surface 21d. As the magnetoresistive element 210, an anisotropic magnetoresistive element (AMR element), a tunnel magnetoresistive element (TMR element), a giant magnetoresistive element (GMR element), or the like can be used. The sensor chip 21 has a substantially rectangular planar plate shape, and the upper surface opposite to the lower surface facing the lead frame 24 serves as a detection surface 21d.

The sensor chip 21 has a first element 211 , a second element 212 , a third element 213 , a fourth element 214 and a fifth element 215 as magnetoresistive elements 210 . The first element 211, the second element 212, the third element 213, the fourth element 214, and the fifth element 215 are configured as a half bridge circuit in which the magnetoresistive effect elements 210 are connected in series. Each of the first element 211, the second element 212, the third element 213, the fourth element 214, and the fifth element 215 is formed by a pair of magnetoresistive elements 210 arranged in a V shape.

As shown in FIG. 4, the first element 211 is composed of two magnetoresistive elements 210 connected in series between a power supply (Vcc) and ground (GND). The first element 211 detects a change in resistance when the two magnetoresistive elements 210 are affected by the magnetic field as the magnetized rotor 10 rotates. The first element 211 outputs the midpoint voltage A of the two magnetoresistive elements 210 as a signal. The second to fifth elements 212 to 215 also have the same configuration as the first element 211 . The second element 212 is composed of two magnetoresistive elements 210 and outputs a midpoint voltage B. FIG.

The third element 213 is composed of two magnetoresistive elements 210 and outputs a midpoint voltage C. As shown in FIG. The fourth element 214 is composed of two magnetoresistive elements 210 and outputs a midpoint voltage D. FIG. The fifth element 215 is composed of two magnetoresistive elements 210 and outputs a midpoint voltage E. FIG.

As shown in FIG. 3, the first element 211 and the second element 212 are arranged such that the center-to-center distance β of the elements is less than the magnetization pitch λ. The third element 213 and the fourth element 214 are arranged such that the center-to-center distance γ of the elements is less than the magnetization pitch λ. The fifth element 215 is arranged between the third element 213 and the fourth element 214 in the direction in which the third element 213 and the fourth element 214 are arranged.

The bias magnet 22 applies a bias magnetic field to the sensor chip 21, that is, to the plurality of magnetoresistive effect elements 210, thereby increasing the magnetic field detection sensitivity of the sensor chip 21 by a certain amount. In this embodiment, the bias magnet 22 has a substantially rectangular planar plate shape. The N pole 22n and S pole 22s of the bias magnet 22 are arranged side by side in the plane defined by the X1-X2 direction and the Y1-Y2 direction. In this embodiment, the N pole 22n and the S pole 22s are arranged side by side in the Y1-Y2 direction, and the boundary 22b between the N pole 22n and the S pole 22s is substantially orthogonal to the Y1-Y2 direction. A magnetic pole center line 22c passing through the magnetic pole centers of the N pole 22n and the S pole 22s is substantially parallel to the Y1-Y2 direction. The bias magnet 22 is arranged so as to overlap the sensor chip 21 in the projection view in the Z1-Z2 direction. Details of the arrangement of the first element 211, the second element 212, the third element 213, the fourth element 214, the fifth element 215, and the bias magnet 22 will be described later.

The circuit chip 23 is a semiconductor chip in which the processing circuit of the sensor chip 21 is formed. The circuit chip 23 has differential amplifiers 230 to 233 , a threshold generator 234 , comparators 235 and 236 and a determination section 237 . In this embodiment, the sensor chip 21 and the circuit chip 23 are arranged side by side in the Y1-Y2 direction with the circuit chip 23 on the Y2 side.

The differential amplifier 230 calculates (AB), which is the difference between the signals A and B, and outputs it as a differential signal S1. A differential amplifier 230 corresponds to a differential section that generates an actuation signal from the outputs of the first element 211 and the second element 212 . The differential signal S1 has a node at the boundary between the N pole 10n and the S pole 10s, as shown in FIG. 5, and has the maximum or minimum amplitude (that is, peak) at the magnetic pole center.

The differential amplifier 231 calculates (EC), which is the difference between the signals E and C, and outputs the result. The differential amplifier 232 calculates (DE), which is the difference between the signals D and E, and outputs the result. The differential amplifier 233 receives (EC) from the differential amplifier 231 and (DE) from the differential amplifier 232 . The differential amplifier 233 calculates (EC)-(DE) and outputs it as a differential signal S2. That is, the differential signal S2=2E-(C+D). Differential amplifiers 231-233 correspond to a differential section that generates actuation signals from the outputs of the third element 213, the fourth element 214, and the fifth element 215. FIG.

The differential signal S2 is a signal having a phase difference with respect to the differential signal S1. For example, as shown in FIG. 5, the differential signal S2 has a peak at the boundary between the N pole 10n and the S pole 10s and a node at the magnetic pole center.

The threshold generator 234 generates a threshold Vth for binarizing the differential signals S1 and S2. The threshold generator 234 is composed of, for example, two resistors (not shown) connected in series between the power supply and the ground, and the midpoint voltage is used as the threshold Vth.

The comparator 235 compares the differential signal S1 with the threshold value Vth and generates a signal S3 by binarizing the differential signal S1. The comparator 236 compares the differential signal S2 with the threshold value Vth and generates a signal S4 by binarizing the differential signal S2.

Based on the signals S3 and S4 output from the comparators 235 and 236, the determination unit 237 determines whether the direction of rotation of the magnetized rotor 10 is forward or reverse. The determination unit 237 outputs information indicating the rotational position of the magnetized rotor 10 and information indicating the rotational direction of the magnetized rotor 10 to an external device (not shown) via the output terminal 27 (Vout). Information indicating the rotational position is based on either of the signals S3 and S4 described above.

In the case of forward rotation, the amplitude of the differential signal S2 is smaller than the threshold Vth before time T1 and becomes larger than the threshold Vth after time T1, as shown in FIG. 5, for example. Therefore, the signal S4 switches from Lo to Hi at time T1. Further, since the amplitude of the differential signal S1 is greater than the threshold value Vth before and after time T1, the signal S3 becomes Hi at time T1. The determination unit 237 determines that the magnetized rotor 10 is rotating forward when the signal S4 rises from Lo to Hi and the signal S3 is Hi.

In the case of reverse rotation, the amplitude of the differential signal S2 is greater than the threshold Vth before time T1 and less than the threshold Vth after time T1. Therefore, the signal S4 switches from Hi to Lo at time T1. Since the amplitude of the differential signal S1 is greater than the threshold value Vth before and after time T1, the signal S3 becomes Hi at time T1. The determination unit 237 determines that the magnetized rotor 10 is rotating in reverse when the signal S4 falls from Hi to Lo and the signal S3 is Hi.

The rotation detection device 20 has a power terminal 28 (Vcc) and a ground terminal 29 (GND) that are connected to an external device. The rotation detection device 20 is supplied with power from an external device via a power terminal 28 and a ground terminal 29 .

Next, the details of the arrangement of the magnetoresistive element 210 and the bias magnet 22 will be described with reference to FIGS. 3 and 6 to 27. FIG. The magnetized rotor 10 shown in FIGS. 6, 8, 11, 16 and 20 corresponds to FIG. For example, in FIG. 6, rotation in the X2 direction indicates forward rotation, and rotation in the X1 direction indicates reverse rotation. In this embodiment, the angle of the magnetic vector is shown with the counterclockwise direction as the positive direction. It is also assumed that the magnetic vector acting on the element is larger in the bias magnetic field than in the rotor magnetic field. It should be noted that the magnetic vector of the bias magnetic field indicates a state of being unaffected by other magnetic fields including the rotor magnetic field, and the magnetic vector of the composite magnetic field indicates a state of being affected by the rotor magnetic field.

(Relationship between angle of magnetic vector of bias magnetic field and phase of signal)
First, the relationship between the angle of the magnetic vector of the bias magnetic field acting on the element and the phase of the signal will be described with reference to FIGS. 6 to 15. FIG. Hereinafter, as shown in FIG. 6, the magnetic pole center of the N pole 10n is assumed to be a rotational position P1, and the boundary between the N pole 10n and the S pole 10s is assumed to be a rotational position P2 in one magnetization cycle. The magnetic pole center of the S pole 10s is assumed to be a rotational position P3, and the boundary between the S pole 10s and the N pole 10n is assumed to be a rotational position P4. In the case of forward rotation, the positions facing the elements in the magnetized rotor 10 change in the order of P1→P2→P3→P4. 8 to 15, the first element 211 will be described as an example of the element. Also, the reference position of the angle of the magnetic vector is the X1 axis.

As shown in FIG. 6, the direction of the magnetic vector of the magnetized rotor 10 acting on the elements (not shown) is substantially parallel to the Y1-Y2 direction and away from the magnetized surface 10m at the rotational position P1, that is, Y2 direction. At the rotational position P3, the direction is opposite to that at the rotational position P1, that is, the Y1 direction. At the rotational positions P2 and P4, the directions are substantially parallel to the X direction and opposite to each other. Specifically, the X1 direction is at the rotational position P2, and the X2 direction is at the rotational position P4. Therefore, the magnetic vector of the rotor magnetic field rotates 360° during one magnetization cycle, as shown in FIG.

As shown in FIG. 8, when the bias magnet 22 is arranged, the magnetic vector of the bias magnetic field acts on the first element 211 as an element. In FIG. 8, the N pole 22n and the S pole 22s are aligned in the Y1-Y2 direction with the N pole 22n on the Y1 side (the magnetized rotor 10 side), and the bias magnet is arranged such that the boundary 22b is substantially perpendicular to the Y1-Y2 direction. 22 are arranged. Also, the first element 211 is arranged on the boundary 22b, and the direction of the magnetic vector of the bias magnetic field acting on the first element 211 is the Y2 direction.

A magnetic vector of the combined magnetic field of the bias magnetic field and the rotor magnetic field acts on the first element 211 . The direction of the magnetic vector of the rotor magnetic field acting on the first element 211 rotates by 360° during one magnetization cycle as described above. Therefore, the magnetic vector of the synthesized magnetic field changes according to the rotational positions P1 to P4 of the magnetized rotor 10, as shown in FIG.

At the rotational position P1, the direction of the magnetic vector of the rotor magnetic field is the same direction as the magnetic vector of the bias magnetic field, that is, the Y2 direction. Therefore, the magnetic vector of the composite magnetic field is obtained by adding the magnetic vector of the rotor magnetic field to the magnetic vector of the bias magnetic field, and the angle θxy of the magnetic vector of the composite magnetic field is 270°. At the rotational position P2, the direction of the magnetic vector of the rotor magnetic field is the X1 direction. Therefore, the angle θxy of the magnetic vector of the composite magnetic field is larger than 270° and smaller than 360°.

At the rotational position P3, the direction of the magnetic vector of the rotor magnetic field is the opposite direction to the magnetic vector of the bias magnetic field, that is, the Y1 direction. Therefore, the magnetic vector of the composite magnetic field is obtained by subtracting the magnetic vector of the rotor magnetic field from the magnetic vector of the bias magnetic field, and the angle θxy is 270°. At the rotational position P4, the direction of the magnetic vector of the rotor magnetic field is the X2 direction. Therefore, the angle θxy of the magnetic vector of the composite magnetic field is larger than 180° and smaller than 270°.

The output (signal A) of the first element 211 changes according to the rotational positions P1 to P4 as shown in FIG. The output signal has nodes at rotational positions P1 and P3 and peaks at rotational positions P2 and P4. The angle θxy at the node is 270°. The output waveform of the first element 211 becomes a node at rotational positions P1 and P3 where the magnetic vector of the composite magnetic field is in the same direction (Y2 direction) as the magnetic vector of the bias magnetic field.

In FIG. 11, the bias magnet 22 is arranged such that the N pole 22n and the S pole 22s are aligned in the X1-X2 direction with the N pole 22n on the X2 side, and the boundary 22b is substantially perpendicular to the X1-X2 direction. Also, the first element 211 is arranged on the boundary 22b, and the direction of the magnetic vector of the bias magnetic field acting on the first element 211 is the X1 direction. Also in this case, the magnetic vector of the synthesized magnetic field changes according to the rotational positions P1 to P4 of the magnetized rotor 10, as shown in FIG.

At the rotational position P1, the magnetic vector of the rotor magnetic field is in the Y2 direction. Therefore, the angle θxy of the magnetic vector of the composite magnetic field is larger than −90° and smaller than 0°. At the rotational position P2, the magnetic vector of the rotor magnetic field is in the same direction as the magnetic vector of the bias magnetic field, that is, the X1 direction. Therefore, the magnetic vector of the composite magnetic field is obtained by adding the magnetic vector of the rotor magnetic field to the magnetic vector of the bias magnetic field, and the angle θxy of the magnetic vector of the composite magnetic field is 0°.

At the rotational position P3, the magnetic vector of the rotor magnetic field is in the Y1 direction. Therefore, the angle θxy of the magnetic vector of the composite magnetic field is greater than 0° and less than 90°. At the rotational position P4, the magnetic vector of the rotor magnetic field is in the opposite direction to the magnetic vector of the bias magnetic field, that is, the X2 direction. Therefore, the magnetic vector of the composite magnetic field is obtained by subtracting the magnetic vector of the rotor magnetic field from the magnetic vector of the bias magnetic field, and the angle θxy is 0°.

The output (signal A) of the first element 211 changes according to the rotational positions P1 to P4 as shown in FIG. The output signal has nodes at rotational positions P2 and P4 and peaks at rotational positions P1 and P2. The angle θxy at the node is 0°. At rotational positions P2 and P4 where the magnetic vector of the composite magnetic field is in the same direction (X1 direction) as the magnetic vector of the bias magnetic field, the output waveform of the first element 211 becomes a node.

Although not shown, the N pole 22n and the S pole 22s are aligned in the Y1-Y2 direction with the S pole 22s on the Y1 side (the magnetized rotor 10 side), and the direction of the magnetic vector of the bias magnetic field acting on the first element 211. is in the Y1 direction, the signal of the first element 211 has nodes at the rotational positions P1 and P3. The angle θxy at the node is 90°. The output waveform of the first element 211 becomes a node at rotational positions P1 and P3 where the magnetic vector of the composite magnetic field is in the same direction (Y1 direction) as the magnetic vector of the bias magnetic field.

Further, when the N pole 22n and the S pole 22s are arranged in the X1-X2 direction with the S pole 22s on the X2 side, and the direction of the magnetic vector of the bias magnetic field acting on the first element 211 is in the X2 direction, the first element 211 The signal has nodes at rotational positions P2 and P4. The angle at the node is 180°. The output waveform of the first element 211 becomes a node at rotational positions P2 and P4 where the magnetic vector of the composite magnetic field is in the same direction (X2 direction) as the magnetic vector of the bias magnetic field.

Now, as shown in FIG. 14, the phase of the signal is defined. Then, as shown in FIGS. 8 to 10, when the angle of the magnetic vector of the bias magnetic field was 270°, the phase of the signal at the rotational position P1 was 0°. As shown in FIGS. 11 to 13, when the angle of the magnetic vector of the bias magnetic field was 0°, the phase of the rotational position P1 was 270°. Further, as described above, when the angle of the magnetic vector of the bias magnetic field was 90°, the phase of the rotational position P1 was 180°. When the angle of the magnetic vector of the bias magnetic field was 180°, the phase of the rotational position P1 was 90°.

In summary, FIG. 15 shows the relationship between the angle of the magnetic vector of the bias magnetic field acting on the first element 211 (element) and the phase of the signal at the rotational position P1. FIG. 15 shows that changing the angle of the magnetic vector of the bias field can change the phase of the signal. For example, when the angle of the magnetic vector of the bias magnetic field is changed by 90°, the phase of the output signal of the first element 211 can be changed by 90°.

(Arrangement of two elements)
Next, the arrangement of the first element 211, the second element 212, and the bias magnet 22 will be described. As shown in FIG. 16, in the sensor chip 21 of this embodiment, a first element 211 and a second element 212 are formed as two elements on the detection surface 21d. The first element 211 and the second element 212 are arranged side by side in the X1-X2 direction with the first element 211 on the X2 side, and the center-to-center distance between these elements 211 and 212 is β. The center-to-center distance β is the center-to-center distance of the V shape, and is less than the magnetization pitch λ.

Here, a line substantially parallel to the Y1-Y2 direction, which is the direction in which the magnetized surface 10m and the sensor chip 21 face each other, and along the detection surface 21d is defined as a reference line L1. The angle between the reference line L1 and the magnetic vector of the bias magnetic field acting on the first element 211 is θ1, and the angle between the reference line L1 and the magnetic vector of the bias magnetic field acting on the second element 212 is θ2. do. In FIG. 16, the magnetic vector of the bias magnetic field is shown tilted with respect to the reference line L1 in order to make the angles θ1 and θ2 easier to understand.

As described above, in this embodiment, the angle of the magnetic vector is indicated with the counterclockwise direction as the positive direction. Therefore, under an environment where no magnetic field different from the bias magnetic field is applied, if the magnetic vector of the bias magnetic field acting on the first element 211 is tilted toward the second element 212 with respect to the reference line L1, the angle θ1>0. , the angle θ1<0 if the second element 212 is tilted in the opposite direction. On the other hand, if the magnetic vector of the bias magnetic field acting on the second element 212 is tilted toward the first element 211 with respect to the reference line L1, the angle θ2<0. The angle θ2>0.

The first element 211 and the second element 212 are arranged to be shifted in the rotational direction of the magnetized rotor 10, thereby generating a phase difference between the signals A and B (midpoint voltages A and B). The phase difference caused by the arrangement (center-to-center distance β) of the first element 211 and the second element 212 is (β/α)×360° in electrical angle. For example, when β=λ, the phase difference is 180°. Also, when β=λ/2, the phase difference is 90°. Conventionally, the first element and the second element are arranged with respect to the bias magnet so that the angle of the magnetic vector of the bias magnetic field acting on the first element is equal to the angle of the magnetic vector of the bias magnetic field acting on the second element. was placed. For example, the first element and the second element were arranged with respect to the bias magnet such that the magnetic vector in the Y2 direction acts on each of the first element and the second element. Therefore, when β<λ, there is a problem that the amplitude of the differential signal S1 becomes small.

On the other hand, in the present embodiment, considering not only the phase difference caused by the arrangement (center-to-center distance β) but also the phase difference caused by the magnetic vector of the bias magnetic field, the first element 211 and the second element 212 are bias magnets. 22. As described above, since the phases of the signals A and B change by the angle change of the magnetic vector of the bias magnetic field, the phase difference due to the magnetic vector of the bias magnetic field is (θ1-θ2) in electrical angle. Therefore, the phase difference between signals A and B is (β/α)×360°+(θ1−θ2).

FIG. 17 shows the relationship between the phase difference (θ1−θ2) caused by the magnetic vector of the bias magnetic field and the amplitude of the differential signal S1 of the first element 211 and the second element 212. FIG. As shown in FIG. 17, when θ1=θ2, the amplitude of the differential signal S1 is the same as in the conventional configuration. Also, the amplitude of the differential signal S1 becomes maximum when (β/α)×360°+(θ1−θ2)=180° is satisfied. That is, it becomes maximum when (θ1-θ2)=180°-(β/α)×360° is satisfied. Here, it is defined as 180°−(β/α)×360°=θm.

The amplitude of the differential signal S1 increases as (θ1-θ2) increases within the range of 0≤(θ1-θ2)≤θm, and reaches a maximum at (θ1-θ2)=θm. In the range of θm≦(θ1−θ2)≦2×θm, the amplitude decreases as (θ1−θ2) increases, and becomes the same as the amplitude when θ1=θ2 at (θ1−θ2)=2×θm. . Therefore, it is preferable to arrange the first element 211 and the second element 212 with respect to the bias magnet 22 so as to satisfy 0<(θ1−θ2)<2×θm. According to this, the amplitude of the differential signal S1 can be made larger than the conventional one due to the effect of the magnetic vector of the bias magnetic field. In particular, the amplitude of the differential signal S1 can be maximized by arranging the first element 211 and the second element 212 with respect to the bias magnet 22 so as to satisfy (θ1−θ2)=θm.

FIG. 18 shows specific signal waveforms showing the effect of the magnetic vector of the bias magnetic field. The upper part of FIG. 18 shows a reference example, and the lower part shows an example of maximizing the amplitude of the differential signal S1. In the reference example, the directions of the magnetic vectors of the bias magnetic fields acting on the first element 211 and the second element 212 are substantially parallel to each other. Specifically, with the N pole 22n on the Y1 side, the N pole 22n and the S pole 22s are arranged side by side in the Y1-Y2 direction, and the boundary 22b is substantially orthogonal to the Y1-Y2 direction. The directions of the magnetic vectors of the bias magnetic fields acting on the first element 211 and the second element 212 are both in the Y2 direction. That is, θ1=θ2=0°. Also, the center-to-center distance β=λ/2. Therefore, the phase difference between the signals A and B is 90 degrees in electrical angle.

To set the phase difference between the signals A and B to 180° in the same element arrangement as the reference example, (θ1−θ2)=90°. For example, the phase of signal A may be advanced by 45°, or changed by −45°, and the phase of signal B may be retarded by 45°, or changed by +45°. For this reason, in the lower part of FIG. 18, the first element 211 and the second element 212 are arranged at positions where the angle θ1=+45° and the angle θ2=−45°. As a result, the phase difference (θ1−θ2) due to the magnetic vector of the bias magnetic field becomes 90°, and the phase difference between the signals A and B becomes 180° in electrical angle.

3 and 19 show specific examples of the arrangement of the first element 211 and the second element 212 with respect to the bias magnet 22. FIG. In this embodiment, the rectangular plate-shaped bias magnet 22 has a length in the X1-X2 direction of 2.8 mm, a length in the Y1-Y2 direction of 1.4 mm, and a length in the Z1-Z2 direction of 0.65 mm. is employed. In the Z1-Z2 direction, the distance from the surface of the bias magnet 22 on the side of the island 24a to the detection surface 21d of the sensor chip 21 is 0.7 mm. Arrows in FIG. 19 indicate the magnetic field distribution of the bias magnet 22 (magnetic simulation result). FIG. 19 shows the magnetic vector of the bias magnet 22 at a position 0.7 mm away from the surface of the bias magnet 22 in the Z1-Z2 direction, that is, the vector on the same plane as the detection surface 21d.

As shown in FIGS. 3 and 19, in this embodiment, the N pole 22n and the S pole 22s are arranged side by side in the Y direction with the N pole 22n on the Y1 side (the magnetized rotor 10 side). The first element 211 and the second element 212 are arranged at positions overlapping the S pole 22s. The first element 211 and the second element 212 are arranged at positions farther from the magnetized rotor 10 than the boundary 22b. In the X1-X2 direction, the first element 211 and the second element 212 are arranged at positions separated from the magnetic pole center line 22c. The first element 211 is arranged on the X2 side of the magnetic pole center line 22c, and the second element 212 is arranged on the X1 side of the magnetic pole center line 22c. The first element 211 and the second element 212 are arranged line-symmetrically with respect to the magnetic pole center line 22c. As shown in FIG. 19, the direction of the magnetic vector acting on the first element 211 is inclined toward the second element 212 side, and the direction of the magnetic vector acting on the second element 212 is inclined toward the first element 211 side. ing.

(Arrangement of 3 elements)
Next, the arrangement of the third element 213, the fourth element 214, the fifth element 215 and the bias magnet 22 will be described. As shown in FIG. 20, the sensor chip 21 according to the present embodiment has a third element 213, a fourth element 214, and a fifth element 215 as three elements formed on the detection surface 21d. The third element 213 and the fourth element 214 are arranged side by side in the X1-X2 direction with the third element 213 on the X2 side, and the center-to-center distance between these elements 213 and 214 is γ. The center-to-center distance γ is less than the magnetization pitch λ. Also, the fifth element 215 is arranged between the third element 213 and the fourth element 214 in the X1-X2 direction.

Here, the angle between the reference line L1 and the magnetic vector of the bias magnetic field acting on the third element 213 is θ3, and the angle between the reference line L1 and the magnetic vector of the bias magnetic field acting on the fourth element 214 is θ4. and In FIG. 20, the magnetic vector of the bias magnetic field is shown tilted with respect to the reference line L1 in order to make the angles .theta.3 and .theta.4 easier to understand. Under an environment where no magnetic field different from the bias magnetic field is applied, if the magnetic vector of the bias magnetic field acting on the third element 213 is tilted toward the fourth element 214 side with respect to the reference line L1, the angle θ3>0 holds. If the four elements 214 are tilted in the opposite direction, the angle θ3<0. On the other hand, if the magnetic vector of the bias magnetic field acting on the fourth element 214 is tilted toward the third element 213 with respect to the reference line L1, the angle θ4<0. The angle θ4>0.

The third element 213 , the fourth element 214 and the fifth element 215 are arranged to be shifted in the rotational direction of the magnetized rotor 10 . For this reason, as shown in FIG. A difference occurs in the phase of the output signal E (midpoint voltage E).

Here, it is assumed that the fifth element 215 that outputs the signal E is arranged at an intermediate position between the third element 213 and the fourth element 214 . When the phase difference between signals C and D is greater than 0° and less than 180°, signal E and signal (C+D) are in phase as shown in FIG. Therefore, the amplitude of the differential signal S2 (=2E−C−D) increases as the amplitude of the signal (C+D) decreases. When the phase difference between signals C and D is 180°, as shown in FIG. 23, signals C and D have opposite phases and signal (C+D) is constant at zero. Therefore, the amplitude of the differential signal S2 is double that of the signal E. FIG.

When the phase difference between signals C and D is greater than 180° and less than 360°, signal E and signal (C+D) are in opposite phase as shown in FIG. Therefore, the amplitude of the differential signal S2 increases as the amplitude of the signal (C+D) increases. When the phase difference between signals C and D is 360°, as shown in FIG. 25, signal E and signal (C+D) have opposite phases, and signals C and D have the same phase. Therefore, the amplitude of the differential signal S2 is maximized. Thus, in order to increase the differential signal S2, the phase difference between the signals C and D should be brought closer to 360°, more preferably matched.

The phase difference caused by the arrangement (center-to-center distance γ) of signals C and D is (γ/α)×360° in electrical angle. For example, when β=λ/2, the phase difference is 90°. Conventionally, the third element and the fourth element are arranged with respect to the bias magnet so that the angle of the magnetic vector of the bias magnetic field acting on the third element is equal to the angle of the magnetic vector of the bias magnetic field acting on the fourth element. was placed. For example, the third and fourth elements were arranged with respect to the bias magnet such that the Y2 direction magnetic vector acts on each of the third and fourth elements. Therefore, when γ<λ, there is a problem that the amplitude of the differential signal S2 is small.

On the other hand, in the present embodiment, not only the phase difference caused by the arrangement (center-to-center distance γ) but also the phase difference caused by the magnetic vector of the bias magnetic field is taken into consideration, placed against. As described above, since the phases of the signals C and D change by the angle change of the magnetic vector of the bias magnetic field, the phase difference due to the magnetic vector of the bias magnetic field is (θ3-θ4) in electrical angle. Therefore, the phase difference between signals C and D is (γ/α)×360°+(θ3−θ4).

FIG. 26 shows the relationship between the phase difference (θ3−θ4) caused by the magnetic vector of the bias magnetic field and the amplitude of the differential signal S2. When .theta.3=.theta.4, the amplitude of the differential signal S2 is the same as in the conventional configuration. As shown in FIG. 26, the amplitude of the differential signal S2 is maximized when (γ/α)×360°+(θ3−θ4)=360° is satisfied. That is, it becomes maximum when (θ3-θ4)=360°-(γ/α)×360° is satisfied. Here, it is defined as 360°-(γ/α)×360°=θn.

The amplitude of the differential signal S2 increases as (θ3-θ4) increases in the range of 0≦(θ3−θ4)≦θn, and reaches a maximum at (θ3−θ4)=θn. In the range of θm≦(θ3−θ4)≦2×θn, the amplitude decreases as (θ3−θ4) increases, and becomes the same as the amplitude when (θ3−θ4)=2×θm and θ3=θ4. . Therefore, it is preferable to arrange the third element 213 and the fourth element 214 with respect to the bias magnet 22 so as to satisfy 0<(θ3−θ4)<2×θn. According to this, the amplitude of the differential signal S2 can be made larger than the conventional one due to the effect of the magnetic vector of the bias magnetic field. In particular, when the third element 213 and the fourth element 214 are arranged with respect to the bias magnet 22 so as to satisfy (θ3−θ4)=θn, the amplitude of the differential signal S2 can be increased.

FIG. 27 shows specific signal waveforms showing the effect of the magnetic vector of the bias magnetic field. The upper part of FIG. 27 shows a reference example, and the lower part shows an example of maximizing the amplitude of the differential signal S2. In the reference example, the directions of the magnetic vectors of the bias magnetic fields acting on the third element 213 and the fourth element 214 are substantially parallel to each other. Specifically, with the N pole 22n on the Y1 side, the N pole 22n and the S pole 22s are arranged side by side in the Y1-Y2 direction, and the boundary 22b is substantially orthogonal to the Y1-Y2 direction. The directions of the magnetic vectors of the bias magnetic fields acting on the third element 213 and the fourth element 214 are both in the Y2 direction. That is, θ3=θ4=0°. Also, the center-to-center distance γ=λ/2. Therefore, the phase difference between the signals C and D is 90 degrees in electrical angle.

In the same arrangement of elements as in the reference example, (θ3−θ4)=270° to set the phase difference between the signals C and D to 360°. For example, the phase of signal C should be advanced by 135°, that is, changed by −135°, and the phase of signal D should be retarded by 135°, that is, changed by +135°. For this reason, in the lower part of FIG. 27, the third element 213 and the fourth element 214 are arranged at positions where the angle θ3=+135° and the angle θ4=−135°. As a result, the phase difference (.theta.3-.theta.4) due to the magnetic vector of the bias magnetic field becomes 270.degree., and the phase difference between the signals C and D becomes 360.degree. in electrical angle.

3 and 19 show specific examples of the arrangement of the third element 213, the fourth element 214, and the fifth element 215 with respect to the bias magnet 22. FIG. As shown in FIGS. 3 and 19, in this embodiment, the third element 213 and the fourth element 214 are arranged at positions overlapping the S pole 22s. The third element 213 and the fourth element 214 are arranged at positions farther from the magnetized rotor 10 than the boundary 22b. In the X1-X2 direction, the third element 213 and the fourth element 214 are arranged away from the magnetic pole center line 22c. The third element 213 is arranged on the X2 side of the magnetic pole center line 22c, and the fourth element 214 is arranged on the X1 side of the magnetic pole center line 22c. The third element 213 and the fourth element 214 are arranged line-symmetrically with respect to the magnetic pole center line 22c. As shown in FIG. 19, the direction of the magnetic vector acting on the third element 213 is inclined toward the fourth element 214 side, and the direction of the magnetic vector acting on the fourth element 214 is inclined toward the third element 213 side. ing.

The bias magnet 22 has two corners 22r1 and 22r2 on the side opposite to the magnetized rotor 10, that is, on the Y2 side of the boundary 22b. The corner 22r1 is provided on the X2 side, and the corner 22r2 is provided on the X1 side. As shown in FIG. 19, the magnetic vector of the bias magnetic field has a greater inclination with respect to the reference line L1 as it approaches the corners 22r1 and 22r2. The third element 213 is arranged at a position closer to the corner 22r1 than the first element 211 arranged on the X2 side. As a result, θ3>θ1. Also, the fourth element 214 is arranged at a position closer to the corner portion 22r2 than the second element 212 arranged on the X1 side. As a result, θ4<θ2. The absolute value of θ4 is made larger than the absolute value of θ2.

The fifth element 215 is arranged at a position overlapping the N pole 22n. The fifth element 215 is arranged at a position closer to the magnetized rotor 10 than the boundary 22b. The fifth element 215 is arranged at a position closer to the magnetized rotor 10 than the third element 213 and the fourth element 214 are. The fifth element 215 is arranged on the magnetic pole centerline 22c. As a result, the direction of the magnetic vector acting on the fifth element 215 is the Y2 direction. The fifth element 215 is arranged between the third element 213 and the fourth element 214 in the X1-X2 direction. The fifth element 215 is arranged at an intermediate position between the third element 213 and the fourth element 214 . The third element 213, fourth element 214, and fifth element 215 are arranged line-symmetrically with respect to the magnetic pole center line 22c.

Next, the effects of the rotation detection device 20 shown in this embodiment will be described.

In this embodiment, the first element 211 and the second element 212 are arranged with respect to the bias magnet 22 so as to satisfy 0<(θ1−θ2)<2×{180°−(β/α)×360°}. It is Therefore, due to the effect of the magnetic vector of the bias magnetic field, the amplitude of the differential signal S1 can be made larger than before.

In particular, the first element 211 and the second element 212 are arranged with respect to the bias magnet 22 so as to satisfy (β/α)×360°+(θ1−θ2)=180°. As a result, the phase difference between the signals A and B becomes 180 degrees in electrical angle. Therefore, it is possible to maximize the amplitude of the differential signal S1 while satisfying β<λ and downsizing the rotation detecting device 20 .

In this embodiment, a fifth element 215 is arranged between the third element 213 and the fourth element 214 . The third element 213 and the fourth element 214 are arranged with respect to the bias magnet 22 so as to satisfy 0<(θ3−θ4)<2×{360°−(γ/α)×360°}. . According to this, the amplitude of the differential signal S2 can be made larger than before due to the effect of the magnetic vector of the bias magnetic field.

In particular, the third element 213 and the fourth element 214 are arranged with respect to the bias magnet 22 so as to satisfy (γ/α)×360°+(θ3−θ4)=360°. As a result, the phase difference between the signals C and D becomes 360 degrees in electrical angle. Therefore, it is possible to increase the amplitude of the differential signal S2 while satisfying γ<λ and downsizing the rotation detecting device 20 .

Note that the fifth element 215 may be arranged at least between the third element 213 and the fourth element 214 . Preferably, the fifth element 215 is positioned midway between the third element 213 and the fourth element 214 and on the magnetic pole centerline 22c. According to this, the third element 213 and the fourth element 214 are symmetrically arranged with respect to the magnetic pole center line 22c, and the peak of the signal (C+D) and the peak of the signal E coincide. Therefore, the amplitude of the differential signal S2 can be further increased. Especially when (γ/α)×360°+(θ3−θ4)=360° is satisfied, the amplitude of the differential signal S2 can be maximized.

In this embodiment, the fifth element 215 is arranged at a position closer to the magnetized rotor 10 than the boundary 22b. Thereby, detection sensitivity can be improved.

The arrangement of the sensor chip 21 (elements 211 to 215) with respect to the bias magnet 22 can be determined by utilizing the magnetic simulation (magnetic field distribution) shown in FIG. 19, for example. The magnetic field distribution at the position of the detection surface 21d is obtained in an environment where no magnetic field different from the bias magnetic field is applied, and the positions of the elements 211 to 215 can be determined from the result.

In this embodiment, the rotation detecting device 20 has only one bias magnet 22, and the N pole 22n and the S pole 22s are arranged side by side in the direction facing the magnetized surface 10m of the magnetized rotor 10. . According to this, it is possible to reduce the number of parts and downsize the rotation detection device 20 while achieving the above-described effects. Moreover, since the sensor chip 21 can be positioned with respect to one bias magnet 22, the positional accuracy of the elements 211 to 215 with respect to the bias magnet 22 can be improved.

(Second embodiment)
This embodiment can refer to the previous embodiment. Therefore, the description of the parts common to the rotation detection device 20 shown in the preceding embodiment will be omitted.

The rotation detection device 20 of this embodiment includes three elements as the magnetoresistive effect element 210, specifically, a third element 213, a fourth element 214, and a fifth element 215, as in the previous embodiment. And it is configured so that the influence of the external magnetic field can be canceled more effectively.

First, based on FIG. 28, the influence of the external magnetic field on the three elements will be described.

In FIG. 28, the magnetic vector of the bias magnetic field acting on the magnetoresistive effect element 210 is indicated by the dashed arrow, and the magnetic vector of the external magnetic field acting on the magnetoresistive effect element 210 is indicated by the dashed line arrow. The magnetic vector of the combined magnetic field of the bias magnetic field and the external magnetic field is indicated by solid arrows. External magnetic fields having substantially the same magnitude and direction act on the three elements. Δθ represents an angular change from the magnetic vector of the bias magnetic field to the magnetic vector of the composite magnetic field due to the action of the external magnetic field. Δθc indicates the angle change at the third element 213 , Δθd indicates the angle change at the fourth element 214 , and Δθe indicates the angle change at the fifth element 215 .

As noted above, the differential signal S2 of the three elements is 2E-(C+D). Therefore, when the relationship of 2×Δθe=Δθc+Δθd is established for the angle change, the influence of the external magnetic field can be effectively canceled.

However, in the present embodiment, the fifth element 215 is arranged closer to the magnet center 22d, which is the center of the bias magnet 22, than the third element 213 and the fourth element 214 are. The magnet center 22d, ie, the magnet center, is the intersection of the boundary 22b and the magnetic pole centerline 22c. Moreover, since the bias magnet 22 is small due to the integration, it has a magnetic force distribution in the XY plane. Therefore, the magnetic vector of the bias magnetic field is larger in the fifth element 215 than in the third element 213 and the fourth element 214 . Since the magnetic vector of the bias magnetic field acting on the fifth element 215 is large, Δθe also becomes small due to the angular change of the magnetic vector of the composite magnetic field. Therefore, if the magnetoresistive effect elements 210 having the same configuration are used as the three elements, for example, 2×Δθe<Δθc+Δθd.

Next, based on FIG.29 and FIG.30, the structure which can cancel the influence of an external magnetic field effectively is demonstrated.

In this embodiment, as shown in FIG. 29, two types of magnetoresistive effect elements 210 are used. Specifically, a high-sensitivity element 210H shown in FIG. 29(a) and a low-sensitivity element 210L shown in FIG. 29(b) are used.

The magnetoresistive element 210 is formed in a meandering shape (meandering shape) using, for example, Ni--Fe-based material or Ni--Co-based material. In the meander shape, if the extended longitudinal portion is the positive sensitivity portion 210a having positive sensitivity, the folded portion connecting the positive sensitivity portions 210a is substantially orthogonal to the longitudinal direction and is the negative sensitivity portion having negative sensitivity. 210b. The folded portion has a shorter extension length than the longitudinal portion. Although FIG. 29 is a plan view, hatching is applied to distinguish between the positive sensitivity portion 210a and the negative sensitivity portion 210b.

Most of the high sensitivity element 210H is occupied by the high sensitivity section 210a. A plurality of longitudinal portions constituting the positive sensitivity portion 210a are arranged side by side at a predetermined pitch so that their longitudinal directions are substantially parallel to each other. A negative sensitivity portion 210b is provided between both ends of the adjacent positive sensitivity portions 210a. The negative sensitivity portion 210b extends in the lateral direction of the positive sensitivity portion 210a. The other end of the high-sensitivity element 210H is provided at the opposite position in the lateral direction.

In this embodiment, the negative sensitivity part 210b is short-circuited by, for example, Al wiring (not shown). That is, the ends of the adjacent positive sensitivity portions 210a are electrically connected by the Al wiring. Thereby, the high-sensitivity element 210H has substantially the same sensitivity characteristics as a configuration without the negative sensitivity portion 210b.

The low-sensitivity element 210L has a smaller percentage of the positive sensitivity portion 210a than the high-sensitivity element 210H, that is, has a higher percentage of the negative sensitivity portion 210b. Specifically, one end and the other end of the low sensitivity element 210L are arranged on the same side in the short direction. Then, the meandering portion continuing to one end and the meandering portion continuing to the other end are integrally connected on the side opposite to the both ends in the lateral direction. In this way, by providing the meander-shaped portions on both end sides, the ratio of the folded portion, that is, the negative sensitivity portion 210b is increased.

Further, in the low-sensitivity element 210L, the extension length in the lateral direction of the portion connecting the two meandering portions is longer than the folded portion. This also increases the ratio of the negative sensitivity portion 210b. In the low-sensitivity element 210L, unlike the high-sensitivity element 210H, Al wiring is not used for connection. Thus, the low sensitivity element 210L is a less sensitive element than the high sensitivity element 210H.

FIG. 30 shows the arrangement of the magnetoresistive element 210 with respect to the bias magnet 22 in the rotation detection device 20 of this embodiment. The arrangement of the third element 213, fourth element 214 and fifth element 215 is the same as in the previous embodiment (see the three elements shown in FIG. 19). This embodiment differs from the previous embodiment in that a low-sensitivity element 210L is used as the third element 213 and the fourth element 214, and a high-sensitivity element 210H is used as the fifth element 215. FIG.

The third element 213 is configured with the four low-sensitivity elements 210L described above. The four low sensitivity elements 210L are connected in series between power supply (Vcc) and ground (GND). Specifically, two low-sensitivity elements 210L are connected in series on the power supply side (high side), and another two low-sensitivity elements 210L are connected in series on the ground side (low side). A midpoint voltage C is output from a connection point between the second and third low-sensitivity elements 210L.

The two low-sensitivity elements 210L on the high side are provided so that their longitudinal directions are parallel to each other. The two low-sensitivity elements 210L on the low side are provided so that their longitudinal directions are parallel to each other and orthogonal to the longitudinal direction on the high side. One low-sensitivity element 210L on the high side and one low-sensitivity element 210L on the low side are arranged in a V-shape, and the third element 213 has two sets of V-shapes. ing. The fourth element 214 has a configuration similar to that of the third element 213 . A midpoint voltage D is output from the connection point of the second and third low-sensitivity elements 210L.

The fifth element 215 is configured with the four high-sensitivity elements 210H described above. The four sensitive elements 210H are connected in series between power supply (Vcc) and ground (GND). Specifically, two high-sensitivity elements 210H are connected in series on the power supply side (high side), and another two high-sensitivity elements 210H are connected in series on the ground side (low side). A midpoint voltage E is output from the connection point between the second and third high sensitivity elements 210H.

The two high-sensitivity elements 210H on the high side are arranged such that their longitudinal directions are parallel to each other. The two high-sensitivity elements 210H on the low side are provided so that their longitudinal directions are parallel to each other and perpendicular to the longitudinal direction on the high side. One high-side high-sensitivity element 210H and one low-side high-sensitivity element 210H are arranged in a V-shape, and the fifth element 215 has two sets of V-shapes. ing.

As described above, in this embodiment, the fifth element 215 near the magnet center 22d is the high sensitivity element 210H, and the third element 213 and the fourth element 214 far from the magnet center 22d are the low sensitivity elements 210L. . In this way, since the three elements are intentionally made to have different sensitivities, 2×Δθe can be made substantially equal to Δθc+Δθd. Therefore, even if an external magnetic field acts, the fluctuation of the differential signal S2 due to it can be suppressed. That is, the resistance to external magnetic fields can be improved.

In this embodiment, an example in which the fifth element 215 is closer to the magnet center 22d than the third element 213 and the fourth element 214 is shown. When the third element 213 and the fourth element 214 are closer to the magnet center 22d than the fifth element 215, 2×Δθe>Δθc+Δθd. Therefore, the high sensitivity element 210H can be used as the third element 213 and the fourth element 214, and the low sensitivity element 210L can be used as the fifth element 215. FIG.

The configurations of the high-sensitivity element 210H and the low-sensitivity element 210L are not limited to the above examples. The high-sensitivity element 210H should have relatively high sensitivity with respect to the low-sensitivity element 210L, and the low-sensitivity element 210L should have relatively low sensitivity with respect to the high-sensitivity element 210H.

In the present embodiment, an example in which the rotation detection device 20 has only three elements as the magnetoresistive effect elements 210 is shown, but the present invention is not limited to this. As in the previous embodiment, a first element 211 and a second element 212 may be provided in addition to the three elements. As described above, from the midpoint voltage A of the first element 211 and the midpoint voltage B of the second element 211, (AB) is generated as the differential signal S1. Therefore, as the first element 211 and the second element 212 arranged line-symmetrically, it is preferable to use the high-sensitivity element 210H.

The disclosure in this specification is not limited to the illustrated embodiments. The disclosure encompasses the illustrated embodiments and variations thereon by those skilled in the art. For example, the disclosure is not limited to any combination of elements shown in the embodiments. The disclosure can be implemented in various combinations. The disclosed technical scope is not limited to the description of the embodiments. The disclosed technical scope is indicated by the description of the claims, and should be understood to include all modifications within the meaning and range of equivalents to the description of the claims. .

Although an example in which the rotation detection device 20 is sealed with the sealing resin body 25 and molded is packaged, the present invention is not limited to this. For example, a structure in which the sensor chip 21 and the circuit chip 23 are fixed on one surface of a substrate such as a ceramic substrate or a printed circuit board, and the bias magnet 22 is fixed on the back surface of the substrate can also be adopted.

Although an example in which the differential amplifiers 230 to 233 as differential units are formed on the circuit chip 23 has been shown, the present invention is not limited to this. Differential amplifiers 230 - 233 may be integrated into sensor chip 21 .

Although an example in which the rotation detection device 20 has the threshold generation unit 234, the comparators 235 and 236, and the determination unit 237 in the circuit chip 23 is shown, the present invention is not limited to this. The threshold generation unit 234, comparators 235 and 236, and determination unit 237 may be integrated in the sensor chip 21 together with the differential amplifiers 230-233. Further, the rotation detection device 20 does not have the threshold generation unit 234, the comparators 235 and 236, and the determination unit 237. 237 may be used.

Although (EC)-(DE)=2E-(C+D) is shown as the differential signal S2, it is not limited to this. The differential signal S2 may be a differential signal generated from the outputs of the three elements, ie, the third element 213, the fourth element 214, and the fifth element 215. FIG. The influence of the external magnetic field can be canceled at (EC), and the influence of the external magnetic field can be canceled at (DE) as well.

Although an example in which the rotation detection device 20 has the first element 211 and the second element 212, and the third element 213, the fourth element 214, and the fifth element 215 as the magnetoresistive effect elements 210, the present invention is limited to this. not. For example, a configuration having only the first element 211 and the second element 212 may be employed. Alternatively, a structure including only the third element 213, the fourth element 214, and the fifth element 215 may be employed. In either case, information indicating the rotational position of the magnetized rotor 10 can be output.

In the case of the configuration having only the third element 213, the fourth element 214, and the fifth element 215, the differential signal S1 is generated from the outputs of the third element 213 and the fourth element 214, and the third element 213 and the fourth element 214, and the output of the fifth element 215, a differential signal S2 can also be generated. That is, it is also possible to output information indicating the rotational position of the magnetized rotor 10 and information indicating the rotational direction of the magnetized rotor 10 using three elements. However, since the third element 213 and the fourth element 214 are used both as two elements for generating the differential signal S1 and as elements at both ends for generating the differential signal S2, for example, the differential signal S1 , S2 cannot be maximized together. According to the configuration shown in this embodiment, since the first element 211 and the second element 212 and the third element 213 and the fourth element 214 can be individually arranged, the differential signals S1 and S2 can be increased in amplitude.

Further, in addition to the first element 211 and the second element 212, another magnetoresistive element 210 may be provided, and in addition to the third element 213, the fourth element 214, and the fifth element 215, another of magnetoresistive effect elements 210 may be provided. In addition to the first element 211 , the second element 212 , the third element 213 , the fourth element 214 and the fifth element 215 , other magnetoresistive elements 210 may be included.

In this embodiment, an example of supplying the threshold value Vth from the threshold value generator 234 to the comparators 235 and 236 is shown, but the present invention is not limited to this. For example, a threshold value may be set for each of the comparators 235 and 236.

The arrangement of the first element 211 and the second element 212, which are the two elements that generate the differential signal S1, is not limited to the above example. Also, the arrangement of the third element 213, the fourth element 214, and the fifth element 215, which are the three elements that generate the differential signal S2, is not limited to the above example. As shown in FIG. 19, near the magnetic pole center line 22c and near the boundary 22b, the direction of the magnetic vector of the bias magnetic field is substantially along the Y2 direction. Further, at a position farther from the magnetized rotor 10 than the boundary 22b, the magnetic vector is directed toward the magnetic pole center line 22c. Therefore, the first element 211, the second element 212, the third element 213, and the fourth element 214 are positioned farther from the magnetized rotor 10 than the boundary 22b, near the magnetic pole center line 22c and near the boundary 22b. should be placed in a position other than

For example, as in the modified example shown in FIG. may be placed. For example, by making the sensor chip 21 larger than the bias magnet 22, such an arrangement is possible. In FIG. 31 , the third element 213 and the fourth element 214 are arranged at positions that do not overlap the bias magnet 22 . The third element 213 is arranged outside the corner 22r1, and the gradient of the acting magnetic vector is larger than near the corner 22r1. Similarly, the fourth element 214 is arranged outside the corner 22r2, and the gradient of the acting magnetic vector is larger than near the corner 22r2. According to this, even if the center-to-center distance γ cannot be increased, the phase difference between the signals C and D can be brought closer to 360°.

Although an example in which the N pole 22n of the bias magnet 22 is on the magnetized rotor 10 side and the N pole 22n and the S pole 22s are arranged side by side in the Y1-Y2 direction, the present invention is not limited to this. For example, a bias magnet 22 having N poles 22n and S poles 22s arranged side by side in the X1-X2 direction can also be employed. Alternatively, the bias magnet 22 may be arranged such that the N pole 22n and the S pole 22s are aligned, in other words, the magnetic pole center line 22c is inclined with respect to the Y1-Y2 direction and the X1-X2 direction.

Also, by using a plurality of bias magnets 22, the orientation of the magnetic vector of the bias magnetic field acting on each element 211-215 may be optimized. For example, for the third element 213 and the fourth element 214, bias magnets 22 having N poles 22n and S poles 22s arranged in different directions may be used separately.

Although the angle of the magnetic vector is defined with the counterclockwise direction as the positive direction, it is not limited to this. The clockwise direction may be the positive direction. For example, in the case of two elements, the first element 211 is arranged on the X1 side and the second element 212 is arranged on the X2 side.

In the magnetized rotor 10, the outer peripheral end surface (side surface) perpendicular to the rotation axis is the magnetized surface 10m, and the rotation detection device 20 is arranged to face the magnetized surface 10m, but the present invention is not limited to this. As in the modification shown in FIG. 32, one of the annular surfaces may be the magnetized surface 10m instead of the outer peripheral end surface, and the rotation detection device 20 may be arranged to face the magnetized surface 10m.

Reference Signs List 10: Magnetized rotor 10m: Magnetized surface 10n: N pole 10s: S pole 20: Rotation detector 21: Sensor chip 21d: Detection surface 210: Magnetoresistive element 210a: Positive sensitivity part , 210b... negative sensitivity part, 210H... high sensitivity element, 210L... low sensitivity element, 211... first element, 212... second element, 213... third element, 214... fourth element, 215... fifth element, 22 Bias magnet 22b Boundary 22c Magnetic pole center line 22d Magnet center 22n N pole 22r1, 22r2 Corner 22s S pole 23 Circuit chip 230 to 233 Differential amplifier 234 Threshold generation unit 235, 236 Comparator 237 Determination unit 24 Lead frame 24a Island 24b to 24d Terminal 25 Sealing resin body 26 Bonding wire 27 Output terminal 28 Power supply terminal 29... Ground terminal L1... Reference line

Claims (10)

A rotation detection device for detecting the rotation state of a magnetized rotor (10) having a magnetized surface (10 m) in which N and S poles are alternately magnetized in the direction of rotation with a magnetization pitch λ and a magnetization period α. There is
a detection surface (21d) orthogonal to the magnetized surface; and a plurality of magnetoresistive elements (210) formed on the detection surface and whose resistance values change as the magnetized rotor rotates, As the magnetoresistive effect elements, a first element (211), a second element (212) arranged so that the center-to-center distance β from the first element is less than the magnetization pitch λ , and a third element (213 ), a fourth element (214) arranged such that the center-to-center distance γ with the third element is less than the magnetization pitch λ, and a fourth element (214) arranged between the third element and the fourth element a sensor chip (21) containing 5 elements (215) ;
at least one bias magnet (22) for applying a bias magnetic field to the plurality of magnetoresistive elements;
a first differential section (230) for generating a differential signal from the outputs of the first element and the second element;
a second differential section (231, 232, 233) that generates a differential signal from the outputs of the third element, the fourth element, and the fifth element,
The angle between a reference line (L1) parallel to the direction in which the sensor chip and the magnetized surface face each other and along the detection surface and the magnetic vector of the bias magnetic field acting on the first element is θ1 , the angle between the reference line and the magnetic vector of the bias magnetic field acting on the second element is θ2; the angle between the reference line and the magnetic vector of the bias magnetic field acting on the third element is θ3; Assuming that the angle between the reference line and the magnetic vector of the bias magnetic field acting on the fourth element is θ4 ,
In an environment where no magnetic field different from the bias magnetic field is applied, the magnetic vector acting on the first element is tilted toward the second element with respect to the reference line so that θ1>0, and the magnetic vector acts on the second element. the magnetic vector is tilted toward the first element with respect to the reference line and θ2<0, and 2×{180°−(β/α)×360°}>(θ1−θ2)>0 the first element and the second element are positioned relative to the bias magnet to satisfy
In an environment where no magnetic field different from the bias magnetic field is applied, the magnetic vector acting on the third element is tilted toward the fourth element with respect to the reference line so that θ3>0, and the magnetic vector acts on the fourth element. The magnetic vector is tilted toward the third element with respect to the reference line so that θ4<0, and 2×{360°−(γ/α)×360°}>(θ3−θ4)>0 a rotation sensing device wherein said third element and said fourth element are positioned with respect to said bias magnet so as to satisfy a 2. The rotation detecting device according to claim 1, further comprising a determination section (237) that determines the direction of rotation of the magnetized rotor based on the output of the first differential section and the output of the second differential section. The first differential unit outputs a difference between a midpoint voltage of the first element and a midpoint voltage of the second element,
The second differential section includes a first differential amplifier (231) that outputs the difference between the midpoint voltage of the fifth element and the midpoint voltage of the third element, and the midpoint voltage of the fourth element and the A second differential amplifier (232) for outputting the difference between the midpoint voltage of the fifth element and a third differential amplifier (232) for outputting the difference between the output of the first differential amplifier and the output of the second differential amplifier. A rotation sensing device according to claim 1 or claim 2, comprising an amplifier (233). 4. Any one of claims 1 to 3, wherein the first element and the second element are arranged with respect to the bias magnet so as to satisfy (β/α)×360°+(θ1−θ2)=180°. 2. The rotation detection device according to item 1 . 5. Any one of claims 1 to 4, wherein the third element and the fourth element are arranged with respect to the bias magnet so as to satisfy (γ/α)×360°+(θ3−θ4)=360°. 2. The rotation detection device according to item 1 . The rotation detecting device according to any one of claims 1 to 5, wherein the fifth element is arranged at an intermediate position between the third element and the fourth element and on the magnetic pole center line of the bias magnet. . the fifth element is positioned closer to the center (22d) of the bias magnet than the third and fourth elements;
The rotation detecting device according to any one of claims 1 to 6, wherein the sensitivities of the third element and the fourth element are lower than the sensitivity of the fifth element. the third element and the fourth element are arranged closer to the center (22d) of the bias magnet than the fifth element;
The rotation detecting device according to any one of claims 1 to 6, wherein the sensitivity of the fifth element is lower than the sensitivity of the third element and the fourth element. one of the bias magnets;
The rotation detecting device according to any one of claims 1 to 8 , wherein the N pole and S pole of the bias magnet are arranged in the facing direction. 10. The sensor chip according to any one of claims 1 to 9, further comprising a sealing resin body (25) for integrally sealing the sensor chip, the bias magnet, the first differential section, and the second differential section. rotation detection device.

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