JP6848943B2 - Rotation detection system - Google Patents

Description

The present invention relates to a rotation detection system that detects the rotation of an object by detecting a change in a magnetic field that accompanies the rotation of the object.

Generally, an encoder, a potentiometer, or the like detects a rotating motion of a rotating body, for example, a magnetic body such as a gear that rotates with the rotating body, a magnetic detection element arranged apart from the magnetic body, and a bias. A rotation detector or the like provided with a bias magnet that generates a magnetic field is used (see, for example, Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 7-55416 International Publication No. 2015/056346 Japanese Unexamined Patent Publication No. 2015-132696

However, the conventional rotation detection device and the like have a structure in which the rotation detection accuracy is easily affected by the positional deviation between the magnetic detection element and the magnetic rotating body.

The present invention has been made in view of such problems, and an object of the present invention is to provide a rotation detection system capable of more accurately detecting the rotation of an object.

A rotation detection system as an embodiment of the present invention includes a magnetic detector, a first soft ferromagnetic rotating body, and a first magnet. The first soft ferromagnetic rotating body can rotate about the rotation axis with respect to the magnetic detector, and has a first outer edge at a first distance from the rotation axis and a first outer edge in its own rotation direction. It includes a second outer edge at a different position and at a second distance from the axis of rotation. The first magnet has a first magnetic field in which the direction of the first magnetic field line passing through the magnetic detector in a state where the first soft ferromagnetic rotating body is stationary with respect to the magnetic detector is the direction along the rotation axis. Is to be given.

In the rotation detection system as one embodiment of the present invention, the direction of the first magnetic field line in the first magnetic field applied to the magnetic detector by the first magnet is the rotation of the first soft ferromagnetic rotating body. It is substantially aligned with the direction along the axis. Therefore, the rotation detection accuracy by the magnetic detection unit is not easily affected by the relative position between the magnetic detection unit and the first soft ferromagnetic rotating body.

According to the rotation detection system of the present invention, the rotation detection accuracy by the magnetic detection unit is not easily affected by the change in the relative positions of the magnetic detection unit, the first soft ferromagnetic rotating body, and the magnet. Therefore, even when the size is reduced, the rotation of the first soft ferromagnetic rotating body can be accurately detected.

It is the schematic which shows the whole structure example of the rotation detection system as 1st Embodiment. It is a perspective view which shows the partial structure of the rotation detection system shown in FIG. 1 schematically. It is a perspective view which shows the partial structure of the detection module shown in FIG. 1 schematically. It is a front view which shows the partial structure of the rotation detection system shown in FIG. 1 schematically. It is a circuit diagram which shows the circuit structure of the magnetic sensor shown in FIG. FIG. 3 is an exploded perspective view showing an enlarged configuration of a main part of the magnetic sensor shown in FIG. It is explanatory drawing for demonstrating the behavior of the rotation detection system shown in FIG. It is another explanatory diagram for demonstrating the behavior of the rotation detection system shown in FIG. It is a schematic side view which shows the partial configuration example of the rotation detection system as a 2nd Embodiment. FIG. 5 is a schematic perspective view showing a partial configuration example of the rotation detection system shown in FIG. 8A. It is a schematic perspective view which shows the partial configuration example of the rotation detection system as the 3rd Embodiment. 9 is a front view schematically showing a partial configuration of the rotation detection system shown in FIG. 9A. 9 is a side view schematically showing a partial configuration of the rotation detection system shown in FIG. 9A. It is a schematic perspective view which shows the partial configuration example of the rotation detection system as 4th Embodiment. It is a front view which shows the partial configuration example of the rotation detection system as a 1st modification. It is a front view which shows the partial configuration example of the rotation detection system as a 2nd modification. It is a front view which shows the partial configuration example of the rotation detection system as a 3rd modification. It is a perspective view which shows the partial structure of the rotation detection system as a 4th modification typically. It is a front view which shows the partial structure of the rotation detection system as a 4th modification typically. It is a perspective view which shows the partial structure of the rotation detection system as a 5th modification typically. It is a front view which shows the partial configuration example of the rotation detection system as a reference example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The explanation will be given in the following order.
1. 1. First Embodiment An example of a rotation detection system in which a magnetic field is formed by one magnet and the rotation angle of one rotation yoke is detected.
2. Second Embodiment An example of a rotation detection system in which a magnetic field is formed by two magnets and the rotation angle of one rotation yoke is detected.
3. 3. Third Embodiment An example of a rotation detection system in which a magnetic field is formed by one magnet and the rotation angles of two rotating yokes that rotate synchronously are detected.
4. Fourth Embodiment An example of a rotation detection system in which a magnetic field is formed by two magnets and the rotation angles of two rotating yokes that rotate synchronously are detected.
5. Modification example

<1. First Embodiment>
[Rotation detection system configuration]
First, the configuration of the rotation detection system as the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a block diagram showing an outline of an overall configuration example of the rotation detection system. FIG. 2 is a perspective view showing the main components of the rotation detection system. Note that FIG. 2 shows only the rotating yoke 11 and the magnet 6, which will be described later.

As shown in FIG. 1, this rotation detection system includes a rotation module 1 as an object to be measured and a detection module 2 that detects the rotation angle of the rotation module 1. This rotation detection system is a specific example corresponding to the "rotation detection system" of the present invention.

(Rotating module 1)
As shown in FIGS. 1 and 2, the rotary module 1 has, for example, a shaft 10 and an annular rotary yoke 11 provided so as to surround the shaft 10. The rotary yoke 11 contains a soft ferromagnet such as permalloy, and is attached directly or indirectly to the shaft 10 inserted through the opening 11K of the rotary yoke 11. The rotary yoke 11 is provided on the detection module 2 so as to be integrally with the shaft 10 so as to be rotatable in the rotation direction Bθ around the rotary shaft 1J. On the peripheral edge of the rotary yoke 11, a plurality of convex portions 1T and concave portions 1U are alternately and periodically arranged at predetermined intervals along the rotation direction Bθ. Due to the rotation operation of the rotation module 1, the convex portion 1T exists at the position closest to the sensor unit 3 (described later) in the detection module 2, and the concave portion 1U exists at the position closest to the sensor unit 3. The states will be repeated alternately. Therefore, the rotation module 1 can bring about a periodic change of the magnetic field lines 6L (described later) of the magnetic field from the magnet 6 applied to the sensor unit 3 by its own rotation operation. The convex portion 1T includes an outer edge OL1 located at a distance r1 from the rotation axis 1J. The recess 1U includes an outer edge OL2 located at a distance r2 from the rotation shaft 1J. Further, the total number of convex portions 1T or the total number of concave portions 1U in the rotary yoke 11 is referred to as the number of teeth of the rotary yoke 11.
The rotating yoke 11 is a specific example corresponding to the "first soft ferromagnetic rotating body" of the present invention. Further, the convex portion 1T is a specific example corresponding to the "first convex portion" of the present invention, and the concave portion 1U is a specific example corresponding to the "first concave portion" of the present invention. Further, the magnet 6 is a specific example corresponding to the "first magnet" of the present invention.

(Detection module 2)
The detection module 2 includes a sensor unit 3, an arithmetic circuit 4, and a magnet 6. Of the detection modules 2, the sensor unit 3 and the arithmetic circuit 4 are provided on the same substrate 7 as shown in FIG. 3, for example, but the present invention is not limited to this, and the sensor unit 3 and the arithmetic circuit 4 are provided on a plurality of different substrates. You may be. Note that FIG. 3 is a perspective view schematically showing an outline of a partial configuration of the detection module 2 shown in FIG.

(Sensor unit 3)
As shown in FIG. 1, the sensor unit 3 has a magnetic sensor 31 and a magnetic sensor 32. The magnetic sensor 31 detects a change in the magnetic field lines 6L of the magnetic field accompanying the rotation of the rotating yoke 11 and outputs the first signal S1 to the arithmetic circuit 4. Similarly, the magnetic sensor 32 detects a change in the magnetic field line 6L of the magnetic field accompanying the rotation of the rotating yoke 11 and outputs a second signal S2 to the arithmetic circuit 4. However, as shown in FIG. 3, since the magnetic sensor 31 has a detection axis J31 and the magnetic sensor 32 has a detection axis J32 substantially orthogonal to the detection axis J31, the phase of the first signal S1 and the first signal S1 The phases of the signal S2 of 2 are different from each other. For example, when the first signal S1 represents a change in resistance value according to sin θ with respect to the rotation angle θ of the rotation yoke 11, the second signal S2 represents a change in resistance value according to cos θ.

FIG. 4 is a front view schematically showing a partial configuration of the detection module. As shown in FIG. 4, the sensor unit 3 is arranged between the outer edge 11G of the rotary yoke 11 and the magnet 6 in the radial direction Br orthogonal to the rotation axis direction Bz. Therefore, the sensor unit 3 is out of the position where it overlaps with the rotation yoke 11 in the rotation axis direction Bz. The rotation axis direction Bz is the extension direction of the rotation axis 1J.

FIG. 5 is a circuit diagram of the sensor unit 3. As shown in FIG. 5, the magnetic sensor 31 is different from the Wheatstone bridge circuit (hereinafter, simply bridge circuit) 24 including, for example, four magneto-resistive effect (MR) elements 23 (23A to 23D). Includes a detector 25. Similarly, the magnetic sensor 32 includes a bridge circuit 27 including four MR elements 26 (26A to 26D) and a difference detector 28.

In the bridge circuit 24, one ends of the MR element 23A and the MR element 23B are connected at the connection point P1, one ends of the MR element 23C and the MR element 23D are connected at the connection point P2, and the other end of the MR element 23A and the MR element are connected. The other end of the 23D is connected at the connection point P3, and the other end of the MR element 23B and the other end of the MR element 23C are connected at the connection point P4. Here, the connection point P3 is connected to the power supply Vcc, and the connection point P4 is grounded. The connection points P1 and P2 are each connected to the input side terminal of the difference detector 25. The difference detector 25 has a potential difference between the connection point P1 and the connection point P2 when a voltage is applied between the connection point P3 and the connection point P4 (voltage drop generated in each of the MR elements 23A and 23D). The difference) is detected and output as the first signal S1 to the arithmetic circuit 4. Similarly, in the bridge circuit 27, one ends of the MR element 26A and the MR element 26B are connected at the connection point P5, one ends of the MR element 26C and the MR element 26D are connected at the connection point P6, and the other end of the MR element 26A. And the other end of the MR element 26D are connected at the connection point P7, and the other end of the MR element 26B and the other end of the MR element 26C are connected at the connection point P8. Here, the connection point P7 is connected to the power supply Vcc, and the connection point P8 is grounded. The connection points P5 and P6 are connected to the input side terminals of the difference detector 28, respectively. The difference detector 28 has a potential difference between the connection point P5 and the connection point P6 when a voltage is applied between the connection point P7 and the connection point P8 (voltage drop generated in each of the MR elements 26A and 26D). The difference) is detected and output as a second signal S2 to the arithmetic circuit 4.

The arrow with the reference numeral JS1 in FIG. 5 schematically represents the direction of magnetization of the magnetization fixing layer SS1 (described later) in each of the MR elements 23A to 23D and 26A to 26D. That is, the resistance values of the MR elements 23A and 23C change (increase or decrease) in the same direction according to the change of the signal magnetic field from the outside, and the resistance values of the MR elements 23B and 23D are all signals. It indicates that the MR elements 23A and 23C change (decrease or increase) in the opposite direction to the change of the magnetic field. Further, the changes in the resistance values of the MR elements 26A and 26C are 90 ° out of phase with respect to the changes in the resistance values of the MR elements 23A to 23D according to the change in the signal magnetic field from the outside. Each of the resistance values of the MR elements 26B and 26D changes in the opposite direction to the MR elements 26A and 26C according to the change of the signal magnetic field. Therefore, for example, when the rotation module 1 rotates, the resistance values of the MR elements 23A and 23C increase and the resistance values of the MR elements 23B and 23C decrease in a certain angle range. At that time, the resistance values of the MR elements 26A and 26C change with a delay (or advance) of, for example, 90 ° from the change of the resistance values of the MR elements 23A and 23C, and the resistance values of the MR elements 26B and 26D are the MR elements. The changes in the resistance values of 23B and 23D are delayed (or advanced) by 90 °.

FIG. 6 shows an example of the sensor stack SS constituting the main parts of the MR elements 23 and 26. The MR elements 23 and 26 all include a sensor stack SS having substantially the same structure. As shown in FIG. 6, the sensor stack SS has a spin valve structure in which a plurality of functional films including a magnetic layer are laminated. Specifically, the sensor stack SS includes a magnetization-fixed layer SS1 having a magnetization JS1 fixed in a certain direction, an intermediate layer SS2 that does not express a specific magnetization direction, and a magnetization JS3 that changes according to the magnetic flux density of the signal magnetic field. The magnetized free layer SS3 having the above is laminated in order. Note that FIG. 6 shows a no-load state in which an external magnetic field such as the magnetic field H1 is not applied. The magnetization fixing layer SS1, the intermediate layer SS2, and the magnetization free layer SS3 may all have a single-layer structure or a multilayer structure composed of a plurality of layers.

The magnetization fixing layer SS1 is made of a ferromagnetic material such as cobalt (Co), a cobalt iron alloy (CoFe), or a cobalt iron boron alloy (CoFeB). An antiferromagnetic layer (not shown) may be provided on the opposite side of the intermediate layer SS2 so as to be adjacent to the magnetization fixing layer SS1. Such an antiferromagnetic layer is made of an antiferromagnetic material such as a platinum manganese alloy (PtMn) or an iridium manganese alloy (IrMn). The antiferromagnetic layer is in a state where, for example, the spin magnetic moment in the forward direction and the spin magnetic moment in the opposite direction completely cancel each other out, and the direction of the magnetization JS1 of the adjacent magnetization fixing layer SS1 is fixed in the positive direction. Acts like.

The intermediate layer SS2 is a non-magnetic tunnel barrier layer made of magnesium oxide (MgO) when the spin valve structure of the sensor stack SS is a magnetic tunnel junction (MTJ), and is a tunnel current based on quantum mechanics. It is thin enough to pass through. The tunnel barrier layer made of MgO can be obtained, for example, by a sputtering treatment using a target made of MgO, an oxidation treatment of a thin film of magnesium (Mg), or a reactive sputtering treatment of sputtering magnesium in an oxygen atmosphere. .. In addition to MgO, the intermediate layer SS2 can also be formed by using oxides or nitrides of aluminum (Al), tantalum (Ta), and hafnium (Hf). The intermediate layer SS2 may be composed of, for example, a platinum group element such as ruthenium (Ru) or gold (Au) or a non-magnetic metal such as copper (Cu). In that case, the spin valve structure functions as a giant magnetoresistive effect (GMR) film.

The magnetization free layer SS3 is a soft ferromagnetic layer, and is composed of, for example, a cobalt iron alloy (CoFe), a nickel iron alloy (NiFe), a cobalt iron boron alloy (CoFeB), or the like.

The current I1 or the current I2, in which the current I10 from the power supply Vcc is divided at the connection point P3, is supplied to the MR elements 23A to 23D of the bridge circuit 24 in the magnetic sensor 31, respectively. The signals e1 and e2 extracted from the connection points P1 and P2 of the bridge circuit 24 flow into the difference detector 25, respectively. Here, the signal e1 represents a resistance change that changes according to Acos (+ γ) + B (both A and B are constants) when the angle formed by the magnetization JS1 and the magnetization JS3 is γ, and the signal e2 represents Acos (−γ). ) Represents a resistance change that changes according to + B. On the other hand, the current I3 or the current I4, in which the current I10 from the power supply Vcc is divided at the connection point P7, is supplied to the MR elements 26A to 26D of the bridge circuit 27 in the magnetic sensor 32, respectively. The signals e3 and e4 extracted from the connection points P5 and P6 of the bridge circuit 27 flow into the difference detector 28, respectively. Here, the signal e3 represents a resistance change that changes according to Asin (+ γ) + B, and the signal e4 represents a resistance change that changes according to Asin (−γ) + B. Further, the first signal S1 from the difference detector 25 and the second signal S2 from the difference detector 28 flow into the arithmetic circuit 4. In the arithmetic circuit 4, the resistance value corresponding to tanγ is calculated. Here, since γ corresponds to the rotation angle θ of the rotation module 1 with respect to the sensor unit 3, the rotation angle θ can be obtained.

(Calculation circuit 4)
As shown in FIG. 1, the arithmetic circuit 4 includes, for example, a low-pass filter (LPF) 42A, 42B, an A / D conversion unit 43A, 43B, filters 44A, 44B, and a waveform shaping unit 45. , And an angle calculation unit 46.

The low-pass filter 42A is connected to the magnetic sensor 31, and the first signal S1 is input from the magnetic sensor 31. The first signal S1 input to the low-pass filter 42A is input to the waveform shaping unit 45 via the A / D conversion unit 43A and the filter 44A. Similarly, the low-pass filter 42B is connected to the magnetic sensor 32, and the second signal S2 is input from the magnetic sensor 32. The second signal S2 input to the low-pass filter 42B is input to the waveform shaping unit 45 via the A / D conversion unit 43B and the filter 44B.

The waveform shaping unit 45 shapes the waveform of, for example, the first signal S1 transmitted from the magnetic sensor 31 and the second signal S2 transmitted from the magnetic sensor 32. The waveform shaping unit 45 performs, for example, a detection circuit that detects a difference in offset voltage, a difference in amplitude, or a difference in the relative angle between the magnetic sensor 31 and the magnetic sensor 32 and the rotary yoke 11, and corrects the difference. Includes a compensation circuit.

The angle calculation unit 46 is an IC circuit that calculates the magnitude of the rotation angle θ of the rotation yoke 11 in the rotation direction Bθ based on the first signal S1 and the second signal S2. The angle calculation unit 46 is adapted to output a third signal S3 including information on the calculated displacement amount (rotation angle θ) to the outside.

(Magnet 6)
The magnet 6 is located on the opposite side of the rotating yoke 11 with the sensor unit 3 interposed therebetween. The magnet 6 applies a magnetic field including magnetic field lines 6L toward the rotating yoke 11 and the sensor unit 3. The sensor unit 3 detects a change in the direction of the magnetic field line 6L by the magnetic sensor 31 and the magnetic sensor 32. As shown in FIG. 4, the magnetic field applied by the magnet 6 to the sensor unit 3 has a magnetic field line 6L in the direction along the rotation axis 1J at a position passing through the sensor unit 3. The direction of the magnetic field lines 6L changes periodically due to the rotation of the rotating yoke 11. When the rotating yoke 11 is stationary with respect to the magnet 6 and the sensor unit 3, the direction of the magnetic field line 6L passing through the sensor unit 3 is the direction along the rotation axis 1J. The direction along the rotation axis 1J is not limited to the direction completely parallel to the rotation axis 1J, that is, 0 °, and means, for example, a direction forming an angle of ± 30 ° or less with respect to the rotation axis 1J. Therefore, the center of the amplitude in the direction of the fluctuating magnetic field line 6L is preferably 0 °, which is exactly the same as the rotation axis 1J, but may be tilted at an angle of ± 30 ° or less with the 0 ° as the center. Further, the amplitude in the direction of the fluctuating magnetic field lines 6L is preferably, for example, about ± 5 °. Here, in a state where the recess 1U of the rotary yoke 11 is closest to the magnet 6, the direction of the magnetic field line 6L substantially coincides with the rotation axis direction Bz at the position where it passes through the sensor unit 3. It is preferable that the magnetizing direction J6 of the magnet 6 substantially coincides with, for example, the rotation axis direction Bz.

[Operation and operation of rotation detection system]
In the rotation detection system of the present embodiment, the rotation angle of the rotation yoke 11 can be detected by the detection module 2 including the sensor unit 3, the calculation circuit 4, and the magnet 6.

In this rotation detection system, as the rotation yoke 11 rotates in the rotation direction Bθ, the convex portion 1T of the rotation yoke 11 approaches or moves away from the magnet 6. Along with such an operation, the vector of the magnetic field line 6L generated by the magnet 6 changes sequentially. Specifically, for example, as shown in FIG. 7A, the magnet 6 is generated when the convex portion 1T of the rotating yoke 11 is away from the magnet 6, that is, when the concave portion 1U is close to the magnet 6. The magnetic field line 6L0 has a vector V0 that substantially coincides with the rotation axis direction Bz. On the other hand, in a state where the convex portion 1T is close to the magnet 6, the magnetic field line 6L1 generated by the magnet 6 has a vector V1 slightly inclined with respect to the rotation axis direction Bz. Therefore, as shown in FIG. 7B, the rotation yoke 11 rotates in the rotation direction Bθ about the rotation axis 1J, that is, with the continuous change of the relative position of the convex portion 1T with respect to the magnet 6, as shown in FIG. 7B. The vector V will perform a precession movement. At this time, the cycle of approaching the convex portion 1T with respect to the magnet 6 coincides with the cycle of change of the vector V of the magnetic field line 6L. The sensor unit 3 includes a Br component along the radial direction Br and a Bθ component along the rotation direction Bθ, which correspond to projection on a plane parallel to the rotation surface (plane orthogonal to the rotation axis 1J) of the rotation yoke 11. The first signal S1 and the second signal S2 are output, respectively. Using the first signal S1 and the second signal S2, the rotation angle and the angular velocity of the rotation yoke 11 are obtained by the arithmetic circuit 4.

[Effect of rotation detection system]
As described above, according to the rotation detection system of the present embodiment, the rotation yoke 11 can rotate about the rotation shaft 1J with respect to the sensor unit 3, and the outer edge OL1 at a distance r1 from the rotation shaft 1J and the rotation shaft. It includes the outer edge OL2 at a distance r2 from 1J. Therefore, the sensor unit 3 can detect a slight fluctuation of the vector V of the magnetic field line 6L of the magnet 6 due to the rotation of the rotating yoke 11. Here, the vector V of the magnetic force line 6L at the position where the magnetic force line 6L passes through the sensor unit 3 is a direction along the rotation axis 1J. Therefore, it is possible to suppress the influence of the accuracy of the relative positions of the rotating yoke 11 and the sensor unit 3 and the magnet 6 on the waveform of the output signal from the sensor unit 3. As a result, according to the rotation detection system of the present embodiment, the rotation of the rotation yoke 11 can be accurately detected even when the rotation detection system is miniaturized.

However, when the magnet 1106 that generates the magnetic field lines 1106L along the radial Br of the rotating body 1011 is arranged as in the rotation detection system as a reference example shown in FIGS. 14A to 14C, for example, The relative positions of the rotating body 1011, the sensor unit 1103, and the magnet 1106 have a great influence on the detection accuracy of the sensor unit 3. Specifically, when the relative positions of the rotating body 1011, the sensor unit 1103, and the magnet 1106 are appropriate, as shown in FIG. 14B, the waveform of the first signal S1 and the second signal S1 The waveform of the signal S2 is good. However, when the relative positions of the rotating body 1011, the sensor unit 1103, and the magnet 1106 are slightly deviated in the radial direction, for example, the waveform of the first signal S1 is distorted as shown in FIG. 14A. This may occur, or the waveform of the second signal S2 may be distorted as shown in FIG. 14 (C). Further, in the rotation detection system of such a reference example, the detection accuracy tends to decrease even if the rotating body 1011 is displaced in the rotation axis direction Bz. The position sensor of Patent Document 1 described above is considered to correspond to the reference example shown in FIGS. 14A to 14C.

On the other hand, according to the rotation detection system of the present embodiment, the allowable range of the relative positions of the rotation yoke 11, the sensor unit 3, and the magnet 6 is wider than that of the rotation detection system as the above reference example. Therefore, it is easy to avoid a decrease in rotation detection accuracy due to a deviation in the arrangement position between the rotation yoke 11 and the sensor unit 3 and the magnet 6. Therefore, even when the size is reduced, the manufacturability is excellent.

<2. Second Embodiment>
Next, the configuration of the rotation detection system as the second embodiment of the present invention will be described with reference to FIGS. 8A and 8B. The rotation detection system of the first embodiment is provided with one magnet 6 for one rotation yoke 11 and one sensor unit 3. On the other hand, the rotation detection system of the second embodiment includes two magnets 6A and 6B for one rotation yoke 11 and one sensor unit 3, as shown in FIGS. 8A and 8B. There is. Except for this point, the rotation detection system of the second embodiment has substantially the same configuration as the rotation detection system of the first embodiment. Note that FIG. 8A is a side view showing the rotation detection system of the second embodiment as viewed from the rotation axis direction Bz. FIG. 8B is a perspective view showing the main components of the rotation detection system of the second embodiment.

As shown in FIGS. 8A and 8B, the magnets 6A and 6B are arranged so as to be separated from each other along the rotation direction Bθ and adjacent to each other. The sensor unit 3 is arranged between the magnet 6A and the magnet 6B in the rotation direction Bθ, and is arranged between the magnet 6A and the magnet 6B and the rotation yoke 11 in the radial direction Br. Both the magnet 6A and the magnet 6B are magnetized along the rotation axis direction Bz, and generate a magnetic field including the magnetic field lines 6AL and the magnetic field lines 6BL, respectively. As shown in FIG. 8B, the magnetic field lines 6AL and the magnetic force lines 6BL have vectors substantially parallel to each other in the direction along the rotation axis 1J at the positions where they pass through the sensor unit 3.

As described above, the same effect as that of the first embodiment can be expected in the second embodiment. Moreover, in the second embodiment, the magnetic field lines 6AL and the magnetic field lines 6BL are generated by the magnets 6A and the magnets 6B arranged adjacent to each other, and the magnetic field lines 6AL and the magnetic force lines 6BL are generated at the positions where the magnetic force lines 6AL and the magnetic force lines 6BL pass through the sensor unit 3. Has a vector in the direction along the axis of rotation 1J. Therefore, an unstable region in which the magnetic field lines 6AL and the magnetic force lines 6BL repel each other is generated in the vicinity of the sensor unit 3, and when the convex portion 1T of the rotating yoke 11 passes in the vicinity of the unstable region, the direction of the vector of the magnetic force lines 6AL. And the direction of the vector of the magnetic field line 6BL changes sensitively. Therefore, in the second embodiment, a larger output change can be obtained in the sensor unit 3 as compared with the first embodiment.

<3. Third Embodiment>
Next, the configuration of the rotation detection system as the third embodiment of the present invention will be described with reference to FIGS. 9A to 9C. FIG. 9A is a schematic perspective view showing a partial configuration example of the rotation detection system as the third embodiment. FIG. 9B is a front view schematically showing a partial configuration of the rotation detection system shown in FIG. 9A. Further, FIG. 9C is a side view schematically showing a partial configuration of the rotation detection system shown in FIG. 9A. The rotation detection system of the first embodiment includes a rotation module 1 in which one rotation yoke 11 is arranged for one sensor unit 3 and one magnet 6. On the other hand, in the rotation detection system of the third embodiment, as shown in FIGS. 9A and 9B, two rotation yokes 11A and 11B are arranged for one sensor unit 3 and one magnet 6. It is equipped with a rotating module 1A. Except for this point, the rotation detection system of the third embodiment has substantially the same configuration as the rotation detection system of the first embodiment. The rotary yoke 11A and the rotary yoke 11B are specific examples corresponding to the "first soft ferromagnetic rotating body" and the "second soft ferromagnetic rotating body" of the present invention, respectively.

The rotary yoke 11A and the rotary yoke 11B are fixedly arranged on the shaft 10 so as to be separated from each other and adjacent to each other in the rotation axis direction Bz. Therefore, the rotary yoke 11A and the rotary yoke 11B can rotate synchronously about the rotation shaft 1J. The sensor unit 3 may be arranged between the rotary yoke 11A and the rotary yoke 11B in the rotation axis direction Bz (see FIG. 9B).

Both the rotary yoke 11A and the rotary yoke 11B have substantially the same configuration as the rotary yoke 11 in the first embodiment. That is, the rotary yoke 11A includes an outer edge OL1 at a distance r1 from the rotary shaft 1J and an outer edge OL2 at a distance r2 from the rotary shaft 1J. The rotary yoke 11A has a plurality of convex portions 1AT including the outer edge OL1 and a plurality of concave portions 1AU including the outer edge OL2 alternately along the rotation direction Bθ. Similarly, the rotary yoke 11B includes an outer edge OL3 at a distance r3 from the rotary shaft 1J and an outer edge OL4 at a distance r4 from the rotary shaft 1J. The rotary yoke 11B has a plurality of convex portions 1BT including the outer edge OL3 and a plurality of concave portions 1BU including the outer edge OL2 alternately along the rotation direction Bθ. As shown in FIG. 9C, in the rotation direction Bθ, the arrangement pitch of the convex portion 1AT and the concave portion 1AU in the rotary yoke 11A and the arrangement pitch of the convex portion 1BT and the concave portion 1BU in the rotary yoke 11B substantially coincide with each other. ing. Moreover, in the rotation axis direction Bz, the concave portion 1BU is located on the extension of the convex portion 1AT and the concave portion 1AU is located on the extension of the convex portion 1BT.

As described above, the same effect as that of the first embodiment can be expected in the third embodiment. Further, since the rotation module 1A of the third embodiment has two rotation yokes 11A and rotation yokes 11B adjacent to each other in the rotation axis direction Bz, the rotation module 1A rotates as compared with the first embodiment. The influence of the positional deviation of the sensor unit 3 and the magnet 6 in the rotation axis direction Bz on the detection accuracy is further reduced. This is because the Bθ component along the rotation direction Bθ in the magnetic field generated from the magnet 6 and the Br component along the radial direction Br in the magnetic field generated from the magnet 6 have a phase difference of 90 ° between the rotation yoke 11A and the rotation yoke 11B. This is because it changes into a sinusoidal shape motivated by the rotation of. Further, since the two rotary yokes 11A and 11B are fixed to the shaft 10 so as to have a constant interval in the rotary axis direction Bz, the sensor unit 3 and the rotary yoke 11A and the rotary yoke 11B are fixed in the rotary axis direction. The misalignment of Bz can be managed by aligning the sensor unit 3 with the shaft 10. Further, by arranging the sensor unit 3 between the rotation yoke 11A and the rotation yoke 11B, for example, when the sensor unit 3 is displaced in the direction away from the rotation yoke 11A along the rotation axis direction Bz, the sensor unit 3 is inevitably The rotation yoke 11B is approached along the rotation axis direction Bz. Therefore, even if the magnetic flux density of the magnetic field extending to the sensor unit 3 decreases as the distance from the rotating yoke 11A decreases, the magnetic flux density of the magnetic field extending to the sensor unit 3 is complemented by the rotating yoke 11B approaching the sensor unit 3. It becomes. Therefore, in the rotation detection module of the present embodiment, it is possible to prevent the detection sensitivity from being lowered due to the influence of the positional deviation between the sensor unit 3 and the rotation module 1A in the rotation axis direction Bz.

<4. Fourth Embodiment>
Next, with reference to FIG. 10, the configuration of the rotation detection system as the fourth embodiment of the present invention will be described. FIG. 10 is a schematic perspective view showing a partial configuration example of the rotation detection system as the fourth embodiment. As shown in FIG. 10, the rotation detection system of the fourth embodiment includes two magnets 6A and 6B and two rotation yokes 11A and 11B for one sensor unit 3. That is, the rotation detection system of the fourth embodiment has a configuration in which the rotation detection system of the second embodiment and the rotation detection system of the third embodiment are combined.

In the fourth embodiment, the same effect as that of the first embodiment can be expected. Further, in the fourth embodiment, a larger output change can be obtained in the sensor unit 3 as compared with the first embodiment, and the rotation axis with respect to the rotation detection accuracy is obtained as compared with the first embodiment. The influence of the misalignment of the sensor unit 3 and the magnet 6 in the direction Bz is further reduced.

<5. Modification example>
Although the present invention has been described above with reference to some embodiments, the present invention is not limited to those embodiments, and various modifications are possible. For example, in the second embodiment described above, the two magnets 6A and 6B are arranged along the rotation direction Bθ of the rotation yoke 11, but the present invention is not limited to this.

(First modification)
In the present invention, for example, as in the rotation detection system as the first modification shown in FIG. 11A, the magnet 6A and the magnet 6B may be arranged so as to be separated and adjacent to each other in the rotation axis direction Bz. .. Also in the first modification, the magnetic field line 6AL generated by the magnet 6A and the magnetic field line 6BL generated by the magnet 6B are in the direction along the rotation axis 1J at the position where they pass through the sensor unit 3. Further, the sensor unit 3 may be arranged between the magnet 6A and the magnet 6B in the rotation axis direction Bz. By arranging the two magnets 6A and 6B in the rotation axis direction Bz in this way, the portion of the magnetic field lines 6AL and 6BL extending in the rotation axis direction Bz is the magnetic field line 6L when only one magnet 6 is arranged. It can be made longer than the portion extending in the rotation axis direction Bz. Therefore, the influence on the rotation detection accuracy due to the relative positional deviation between the sensor unit 3 and the rotation yoke 11 in the rotation axis direction Bz is further reduced. Note that FIG. 11A is an enlarged front view showing a main part of a rotation detection system as a first modification of the present invention.

(Second modification)
In the present invention, for example, as in the rotation detection system as the second modification shown in FIG. 11B, the magnet 6A and the magnet 6B are arranged so as to face each other with the rotation yoke 11 in the rotation axis direction Bz. May be good. Also in the second modification, the magnetic field line 6AL generated by the magnet 6A and the magnetic field line 6BL generated by the magnet 6B are in the direction along the rotation axis 1J at the position where they pass through the sensor unit 3. Further, the sensor unit 3 may be arranged between the magnet 6A and the magnet 6B in the rotation axis direction Bz. The second modification is more advantageous than the first modification when sufficient space cannot be secured in the radial Br. Note that FIG. 11B is an enlarged front view showing a main part of the rotation detection system as a second modification of the present invention.

(Third variant)
In some of the above embodiments, the magnetizing direction of the magnet is set to be along the rotation axis direction Bz, but the present invention is not limited to this. In the present invention, for example, as in the rotation detection system as the third modification shown in FIG. 11C, the magnetizing direction J6A of the magnet 6A and the magnetizing direction J6B of the magnet 6B are in the radial direction orthogonal to the rotation axis direction Bz. It may be set to Br. However, also in this third modification, the magnetic field lines 6AL and 6BL generated by the magnet 6A are in the direction along the rotation axis 1J at the position where they pass through the sensor unit 3. Further, the sensor unit 3 may be arranged between the magnet 6A and the magnet 6B in the rotation axis direction Bz. Note that FIG. 11C is an enlarged front view showing a main part of the rotation detection system as a third modification of the present invention.

(Fourth modification)
Further, in the present invention, the magnets 6 may be provided with yokes 8A and 8B, for example, as in the rotation detection system as the fourth modification shown in FIGS. 12A and 12B. In this fourth modification, a pair of yokes 8A and 8B are arranged so as to sandwich the magnet 6 along the magnetizing direction J6 of the magnet 6. Due to the presence of the yokes 8A and 8B, the direction of the magnetic field lines 6L can be controlled, and the magnetic flux density along the magnetic field lines 6L can be further increased with respect to the sensor unit 3. In particular, the yokes 8A and 8B include vents 8AT and 8BT curved so as to go from the magnet 6 to the sensor unit 3, respectively. Therefore, the magnetic flux density along the magnetic field lines 6L passing through the sensor unit 3 can be further increased. Therefore, in this modified example, higher detection sensitivity can be expected. 12A and 12B are perspective views and front views showing the main parts of the rotation detection system as a fourth modification of the present invention in an enlarged manner, respectively. However, in FIG. 12A, the illustration of the sensor unit 3 is omitted.

(Fifth variant)
Further, in the above embodiment, the planar shape of the rotating yoke 11 in the rotating plane (in the Br−Bθ plane) is a petal shape in which a plurality of convex portions 1T and a plurality of concave portions 1U are alternately arranged. However, the present invention is not limited to this. For example, as in the rotation module 1B shown in FIG. 13, a cam-shaped rotary yoke 51A having only one convex portion 1AT and a cam-shaped rotary yoke 51B having only one convex portion 1BT may be provided. The outer edge OL3A in the convex portion 1AT protrudes in the radial direction Br from the outer edge OL4A in the other portion. Similarly, the outer edge OL3B in the convex portion 1BT protrudes in the radial direction Br from the outer edge OL4B in the other portion. Further, in the rotation direction Bθ, the position of the convex portion 1AT and the position of the convex portion 1BT are different from each other. By providing such cam-shaped rotating yokes 51A and 51B, angle information of 0 ° to 360 ° can be obtained by one rotation of the rotating yokes 51A and 51B, so that the absolute value of the rotation angle of the shaft 10 can be determined. it can. However, in the case of the petal-shaped rotating yoke 11 shown in FIG. 2 and the like, a plurality of convex portions 1T and a plurality of concave portions 1U are included. Therefore, one rotation of the rotary yoke 11 makes it possible to obtain angle information of 0 ° to 360 ° a plurality of times, which makes it difficult to obtain an absolute value of the rotation angle of the shaft 10.

On the other hand, in the case of the petal-shaped rotating yoke 11 shown in FIG. 2 and the like, there is an advantage that a plurality of convex portions 1T and a plurality of concave portions 1U are included. For example, when detecting the rotation angle of a motor with a conventional resolver or the like, it is desirable for control to have a yoke having unevenness several times as many as the number of poles of the motor. Suitable for. Further, in the petal-shaped rotating yoke 11, the number of convex portions (concave portions) can be freely changed according to the number of poles of the motor. Further, in the case of a concave-convex yoke having a continuous contour line like the rotary yoke 11, the minimum resolution is not limited, and an angular output that changes linearly with respect to the rotation angle can be obtained. However, in the case of an encoder, since the minimum resolution of the numerical value of the obtained angle is determined by the width of the reference clock signal, an angle output that changes stepwise with respect to the rotation angle can be obtained.

Further, in the above-described embodiment and the like, two magnetic detection elements are provided, but in the present invention, the number of magnetic detection elements is not limited to two, and may be only one or three or more. May be good. However, when three or more magnetic detector elements are provided, it is desirable that they output signals having different phases.

Further, in the first embodiment, the magnetic sensor 31 and the magnetic sensor 32 including the magnetoresistive sensor, respectively, have been described as examples as the magnetic detection element, but the present invention is not limited thereto. That is, the magnetic detection element of the present invention is not particularly limited as long as it can detect a change in the direction (angle) of the magnetic field, and may be, for example, a Hall element.

Further, the magnetic detection unit of the present invention may include one or more two-axis magnetic detection elements having a first detection axis and a second detection axis orthogonal to each other. Alternatively, the magnetic detector of the present invention brings the first magnetic detector element having the first detection axis and the second magnetic detector element having the second detection axis orthogonal to the first detection axis close to each other. A plurality of arranged magnetic detector element pairs may be provided. When the above-mentioned two-axis magnetic detector elements are arranged at a plurality of locations and when the above-mentioned magnetic detector pair is arranged at a plurality of locations, the arrangement pitch thereof is the rotation direction of the soft ferromagnetic rotating body. Then, for example, it is desirable that it matches the arrangement pitch of the convex portion of the soft ferromagnetic rotating body. Further, in the axial direction of the soft ferromagnetic rotating body, it is desirable that the plurality of two-axis magnetic detection elements or the plurality of magnetic detection element pairs are substantially equidistant from each other with respect to the central surface of the magnet.

1,1A, 1B ... Rotating module, 1T ... Convex, 1U ... Concave, 10 ... Shaft, 11 ... Rotating yoke, 2 ... Detection module, 3 ... Sensor, 31, 32 ... Magnetic sensor, 4 ... Computational circuit, 46 ... angle calculation unit, 6 ... magnet, 6L ... magnetic field line, 7 ... substrate, 8A, 8B ... yoke, Bθ ... rotation direction, Br ... radial direction, Bz ... rotation axis direction, H1 ... magnetic field.

Claims (25)

Magnetic detector and
The rotation is possible with respect to the magnetic detector about the rotation axis, and is at a position different from the first outer edge at a first distance from the rotation axis and the first outer edge in its own rotation direction. A first soft ferromagnetic rotating body including a second outer edge at a second distance from the axis, and
A first magnetic field is applied to the magnetic detector in a state where the first soft ferromagnetic rotating body is stationary and the direction of the first magnetic field line passing through the magnetic detector is along the axis of rotation. The first magnet and
A second magnetic field is applied to the magnetic detector in a state where the first soft ferromagnetic rotating body is stationary and the direction of the second magnetic field line passing through the magnetic detector is along the axis of rotation. Bei example and a second magnet,
A rotation detection system in which the first magnet and the second magnet are separated from each other in the rotation direction of the first soft ferromagnetic rotating body and are adjacent to each other. With the rotation of the first soft ferromagnetic rotating body around the rotation axis, the direction of the first magnetic field line fluctuates periodically.
The rotation detection system according to claim 1, wherein the magnetic detection unit detects the direction of the first magnetic field line that fluctuates periodically. The rotation detection system according to claim 1 or 2, wherein the magnetizing direction of the first magnet substantially coincides with the direction along the rotation axis. The rotation detection system according to any one of claims 1 to 3, wherein the magnetic detection unit is arranged between the first soft ferromagnetic rotating body and the first magnet. The magnetic detector is arranged between the first soft ferromagnetic rotating body and the first magnet, or between the first soft ferromagnetic rotating body and the second magnet. The rotation detection system according to any one of items 1 to 4. The magnetic detector is arranged between the first magnet and the second magnet in the rotation direction of the first soft ferromagnetic rotating body. Any one of claims 1 to 5. rotation detecting system according to. The first soft ferromagnetic rotating body has a first convex portion including the first outer edge and a first concave portion including the second outer edge in a rotation direction of the first soft ferromagnetic rotating body. The rotation detection system according to any one of claims 1 to 6 , wherein a plurality of rotation detection systems are alternately provided along the same line. It is rotatable about the rotation axis in synchronization with the first soft ferromagnetic rotating body, and is at a third outer edge at a third distance from the rotation axis and a fourth distance from the rotation axis. Any of claims 1 to 7 , further comprising a fourth outer edge and a second soft ferromagnetic rotating body adjacent to the first soft ferromagnetic rotating body in a direction along the rotation axis. The rotation detection system according to item 1. The rotation detection system according to claim 8 , wherein the magnetic detector is arranged between the first soft ferromagnetic rotating body and the second soft ferromagnetic rotating body in a direction along the rotation axis. .. The first soft ferromagnetic rotating body has a first convex portion including the first outer edge and a first concave portion including the second outer edge in the rotation direction of the first soft ferromagnetic rotating body. Have multiple alternating along the
The second soft ferromagnetic rotating body has a second convex portion including the third outer edge and a second concave portion including the fourth outer edge in the rotation direction of the second soft ferromagnetic rotating body. Have multiple alternating along
The rotation detection system according to claim 8 or 9. In the rotation direction, the arrangement pitch of the first convex portion and the first concave portion in the first soft ferromagnetic rotating body and the second convex portion in the second soft ferromagnetic rotating body. It substantially coincides with the arrangement pitch with the second recess.
10. The tenth aspect of the present invention, wherein the second concave portion is located on an extension of the first convex portion and the first concave portion is located on an extension of the second convex portion in a direction along the rotation axis. Rotation detection system. From claim 1, the magnetic detection unit includes a first magnetic detection element having a first detection axis and a second magnetic detection element having a second detection axis intersecting the first detection axis. The rotation detection system according to any one of claim 11. Both the first magnet and the second magnet are magnetized in the direction along the rotation axis.
The rotation detection system according to any one of claims 1 to 12. Magnetic detector and
The rotation is possible with respect to the magnetic detector about the rotation axis, and is at a position different from the first outer edge at a first distance from the rotation axis and the first outer edge in its own rotation direction. A first soft ferromagnetic rotating body including a second outer edge at a second distance from the axis, and
The direction of the first magnetic field line passing through the magnetic detector in the state where the first soft ferromagnetic rotating body is stationary while maintaining the stationary state with respect to the magnetic detector is the direction along the rotation axis. A first magnet that applies a first magnetic field to the magnetic detector,
It is rotatable about the rotation axis in synchronization with the first soft ferromagnetic rotating body, and is at a third outer edge at a third distance from the rotation axis and a fourth distance from the rotation axis. With the second soft ferromagnetic rotating body including the fourth outer edge and adjacent to the first soft ferromagnetic rotating body in the direction along the rotation axis.
With
Rotation detection system. The magnetic detector is arranged between the first soft ferromagnetic rotating body and the second soft ferromagnetic rotating body in the direction along the rotation axis.
The rotation detection system according to claim 14. The first soft ferromagnetic rotating body has a first convex portion including the first outer edge and a first concave portion including the second outer edge in the rotation direction of the first soft ferromagnetic rotating body. Have multiple alternating along the
The second soft ferromagnetic rotating body has a second convex portion including the third outer edge and a second concave portion including the fourth outer edge in the rotation direction of the second soft ferromagnetic rotating body. Have multiple alternating along
The rotation detection system according to claim 14 or 15. In the rotation direction, the arrangement pitch of the first convex portion and the first concave portion in the first soft ferromagnetic rotating body and the second convex portion in the second soft ferromagnetic rotating body. It substantially coincides with the arrangement pitch with the second recess.
In the direction along the rotation axis, the second concave portion is located on the extension of the first convex portion, and the first concave portion is located on the extension of the second convex portion.
The rotation detection system according to claim 16. With the rotation of the first soft ferromagnetic rotating body around the rotation axis, the direction of the first magnetic field line fluctuates periodically.
The magnetic detector detects the direction of the first magnetic field line that fluctuates periodically.
The rotation detection system according to any one of claims 14 to 17. The magnetizing direction of the first magnet substantially coincides with the direction along the rotation axis.
The rotation detection system according to any one of claims 14 to 18. The magnetic detector is arranged between the first soft ferromagnetic rotating body and the first magnet.
The rotation detection system according to any one of claims 14 to 19. The magnetic detection unit is further provided with a second magnet that applies a second magnetic field in which the direction of the second magnetic field line passing through the magnetic detection unit is the direction along the rotation axis.
The rotation detection system according to any one of claims 14 to 20. The magnetic detector is arranged between the first soft ferromagnetic rotating body and the first magnet, or between the first soft ferromagnetic rotating body and the second magnet.
The rotation detection system according to claim 21. The first magnet and the second magnet are adjacent to each other in the direction along the rotation axis.
The rotation detection system according to claim 21 or 22. The magnetic detector is arranged between the first magnet and the second magnet in a direction along the rotation axis.
The rotation detection system according to claim 23. Both the first magnet and the second magnet are magnetized in the direction along the rotation axis.
The rotation detection system according to any one of claims 21 to 24.

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