JP6915642B2 - Position detection system - Google Patents

Description

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

The applicant has so far provided a magnetic sensing element and a plurality of magnetic members arranged in a row so as to face the magnetic sensing element, and uniquely specified the position of the magnetic sensing element with respect to the plurality of magnetic members. We have proposed a possible magnetic position detector (see, for example, Patent Document 1).

Patent No. 501146

By the way, since the angle detection range of the magnetic sensing element is generally limited to 0 ° to 360 °, in the magnetic position detecting device of Patent Document 1, the detection target is more than the arrangement pitch of a plurality of magnetic members. It is a necessary condition that the amount of movement of the object is small. Therefore, when the amount of movement of the object to be detected is large, the arrangement pitch of the plurality of magnetic members must be increased.

The present invention has been made in view of such problems, and an object of the present invention is to provide a position detection system capable of more accurately detecting the position of a moving object while having a compact configuration.

A position detection system as an embodiment of the present invention includes a first magnet, a first soft ferromagnet, and a magnetic detector. The first magnet has a magnetization magnetized in the first direction and forms a first magnetic field containing the first field line. The first soft ferromagnetic material extends along a second direction orthogonal to the first direction, is movable straight along the second direction with respect to the first magnet, and has a first direction. A third outer edge portion at a first distance from the first magnet in a third direction orthogonal to both the second direction and a third outer edge portion at a different position from the first outer edge portion in the second direction. It has a first outer edge including a second outer edge portion at a second distance from the first magnet in the direction of. The magnetic detector is provided so that the position relative to the first magnet is kept constant and the first magnetic field line passes through itself in the first direction when the first soft ferromagnet is stationary. There is.

In the position detection system as one embodiment of the present invention, the direction of the first magnetic field line in the first magnetic field applied by the first magnet to the magnetic detection unit is linearly moved by the first soft ferromagnetic material. It is substantially orthogonal to the second direction. Therefore, the accuracy of detecting the position of the first soft ferromagnet by the magnetic detector is not easily affected by the relative position between the magnetic detector and the first soft ferromagnet. Further, the position of the first soft ferromagnet with respect to the magnetic detector is detected without the first magnet moving with respect to the magnetic detector.

According to the position detection system of the present invention, the accuracy of detecting the position of the first soft ferromagnet by the magnetic detector is a change in the relative position between the magnetic detector, the first soft ferromagnet and the first magnet. Is not easily affected by. Therefore, even when the size is reduced, the position of the first soft ferromagnet can be accurately detected. Since the first magnet does not move with respect to the magnetic detector, the amount of movement of the first soft ferromagnet in the second direction can be increased without increasing the size of the first magnet. Therefore, according to the position detection system of the present invention, the position of a moving object can be detected more accurately even though the configuration is compact. Further, according to the position detection system of the present invention, the first magnet does not move with respect to the magnetic detector, and the direction of the magnetic field generated by the first magnet changes due to the movement of the first soft ferromagnet. Is detected by the magnetic detector. Therefore, the magnetic field strength required for detection by the magnetic detector can be stably obtained. Therefore, the amount of movement of the first soft ferromagnet in the second direction can be increased without increasing the size of the first magnet. Therefore, according to the position detection system of the present invention, the position of a moving object can be detected more accurately even though the configuration is compact.

It is the schematic which shows the whole structure example of the position detection system as 1st Embodiment. It is a perspective view which shows the partial structure of the position detection system shown in FIG. 1 schematically. It is a front view which shows the partial structure of the position 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 side view which shows the partial structure of the position detection system shown in FIG. 1 schematically. It is a circuit diagram which shows the circuit structure of the magnetic sensor shown in FIG. It is an exploded perspective view which shows the main part structure of the magnetic sensor shown in FIG. 4 in an enlarged manner. It is explanatory drawing for demonstrating the behavior of the position detection system shown in FIG. It is another explanatory diagram for demonstrating the behavior of the position detection system shown in FIG. It is a perspective view which shows typically the partial configuration example of the position detection system as the 2nd Embodiment. 9 is a front view schematically showing a partial configuration example of the position detection system shown in FIG. 9A. FIG. 5 is a first explanatory diagram schematically showing changes in magnetic field lines during the operation of the position detection system shown in FIG. 9. FIG. 2 is a second explanatory diagram schematically showing changes in magnetic field lines during the operation of the position detection system shown in FIG. 9. FIG. 3 is a third explanatory diagram schematically showing changes in magnetic field lines during the operation of the position detection system shown in FIG. 9. FIG. 5 is a characteristic diagram showing the relationship between the amount of movement of the magnetic yoke and the output from the sensor unit in the position detection system shown in FIG. It is a perspective view which shows typically the partial configuration example of the position detection system as the 3rd Embodiment. FIG. 6 is a front view schematically showing a partial configuration example of the position detection system shown in FIG. 14A. FIG. 14 is another perspective view schematically showing a partial configuration example of the position detection system shown in FIG. 14A. It is a perspective view which shows the partial configuration example of the position detection system as a modification of this invention schematically. It is a front view which shows typically the partial configuration example of the position 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 position detection system in which a magnetic field is formed by one magnet and the position of one magnetic yoke in the uniaxial direction is detected.
2. Second Embodiment An example of a position detection system that forms a magnetic field with one magnet and detects the position in the uniaxial direction of two magnetic yokes that move linearly in synchronization.
3. 3. Third Embodiment An example of a position detection system that forms a magnetic field with two magnets and detects the uniaxial position of two magnetic yokes that move linearly in synchronization.
4. Modification example

<1. First Embodiment>
[Position detection system configuration]
First, the configuration of the position detection system 1 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 position detection system 1. Further, FIG. 2 is a perspective view showing the main components of the position detection system 1, and FIG. 3 is a front view showing the main components of the position detection system 1. Note that FIG. 2 shows only the magnetic yoke 10 and the magnet 6 described later, and FIG. 3 shows only the magnetic yoke 10, the magnet 6 and the sensor unit 3 described later.

As shown in FIG. 1, the position detection system 1 includes a magnetic yoke 10 fixed to a moving body as an object to be measured, and a detection module 2 for detecting the position of the magnetic yoke 10 in the X-axis direction. ing. The position detection system 1 is a specific example corresponding to the "position detection system" of the present invention.

(Magnetic yoke 10)
The magnetic yoke 10 is a plate-shaped member that extends so as to have the X-axis direction as the longitudinal direction and has a thickness in the Y-axis direction orthogonal to the X-axis direction. The magnetic yoke 10 is provided so as to be movable linearly in the + X direction and the −X direction along the X axis with respect to the detection module 2 including the magnet 6. The magnetic yoke 10 has an outer edge 11 facing the sensor unit 3 and the magnet 6 in the detection module 2 in the Z-axis direction. The Z-axis direction is orthogonal to both the X-axis direction and the Y-axis direction. The outer edge 11 is located at a distance of 11D (FIG. 2) from, for example, the magnet 6 in the Z-axis direction. Here, the outer edge 11 is not flat and has a concave-convex shape including, for example, a convex portion 11T and a concave portion 11U. More specifically, the outer edge 11 has a shape in which the distance 11D from the magnet 6 in the Z-axis direction periodically fluctuates in the X-axis direction so as to draw a sinusoidal curve, that is, a continuous curved surface. The convex portion 11T is a first outer edge portion at a first distance D1 from the magnet 6 in the Z-axis direction. Further, the concave portion 11U is a second outer edge portion located at a position different from the convex portion 11T in the X-axis direction and at a second distance D2 from the magnet 6 in the Z-axis direction. Here, the first distance D1 is the minimum value of the distance 11D, and the second distance D2 is the maximum value of the distance 11D. The length from the convex portion 11T to the concave portion 11U in the X-axis direction corresponds to the half-period length 0.5T of the sinusoidal curve drawn by the outer edge 11. The magnetic yoke 10 contains a soft ferromagnet such as permalloy as a main component.

Here, the movable length L10 (FIG. 3) of the magnetic yoke 10 in the X-axis direction is preferably equal to or less than the length 1T of one cycle in the X-axis direction of the outer edge 11. This is because the absolute position of the magnetic yoke 10 as a moving body in the X-axis direction can be easily specified. The start point and the end point of the movable length L10 may be the same as or different from the position of the convex portion 11T and the position of the concave portion 11U in the X-axis direction.

The magnetic yoke 10 can bring about a periodic change of the magnetic field line 6L (described later) of the magnetic field from the magnet 6 applied to the sensor unit 3 by its own moving motion along the X axis. The magnetic yoke 10 is a specific example corresponding to the "first soft ferromagnet" 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. 4, 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. 4 is a perspective view schematically showing an outline of a partial configuration of the detection module 2 shown in FIG. Here, the sensor unit 3 is a specific example corresponding to the "magnetic detector unit" of the present invention. Further, the magnet 6 is a specific example corresponding to the "first magnet" of the present invention.

(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 line 6L (described later) of the magnetic field due to the movement of the magnetic yoke 10 in the + X direction or the movement in the −X direction, and outputs the first signal S1 to the arithmetic circuit 4. It has become. Similarly, the magnetic sensor 32 detects a change in the magnetic field line 6L of the magnetic field due to the movement of the magnetic yoke 10 and outputs a second signal S2 to the arithmetic circuit 4.

As shown in FIG. 4, the magnetic sensor 31 has a detection axis J31 along the X-axis direction, and the magnetic sensor 32 has a detection axis J32 along the Z-axis direction so as to be substantially orthogonal to the detection axis J31. Have. Therefore, the phase of the first signal S1 and the phase of the second signal S2 are different from each other. For example, when the first signal S1 represents a change in resistance value according to sinθ with respect to the amount of movement ΔX (see FIGS. 2 and 3) of the magnetic yoke 10 in the X-axis direction, the second signal S2 follows cosθ. It represents the change in resistance value.

FIG. 5 is a side view schematically showing a partial configuration of the detection module 2. As shown in FIG. 5, the sensor unit 3 is provided between the magnet 6 and the magnetic yoke 10 in the Z-axis direction in which the magnet 6 and the magnetic yoke 10 face each other. They are arranged apart from both sides. Further, the center position CP3 of the sensor unit 3 in the Y-axis direction and the center position CP10 of the magnetic yoke 10 in the Y-axis direction are different in the Y-axis direction. In particular, in the present embodiment, the sensor unit 3 is provided at a position deviated from the position where it overlaps with the magnetic yoke 10 in the Z-axis direction.

FIG. 6 is a circuit diagram of the sensor unit 3. As shown in FIG. 6, 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 arrows with the reference numerals JS1 in FIG. 6 schematically represent 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 external magnetic field, and the resistance values of the MR elements 23B and 23D all change in the signal magnetic field. It means that the MR elements 23A and 23C change (decrease or increase) in the opposite direction to the MR elements 23A and 23C. 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 magnetic yoke 10 of the position detection system 1 moves, the resistance values of the MR elements 23A and 23C increase and the resistance values of the MR elements 23B and 23D 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. 7 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. 7, 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 exhibit magnetization in a specific 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 a magnetic field formed by the magnet 6 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 movement amount ΔX of the magnetic yoke 10 with respect to the sensor unit 3, the movement amount ΔX of the magnetic yoke 10 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. It has an angle calculation unit 46 and a position calculation unit 47.

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 position between the magnetic sensor 31 and the magnetic sensor 32 and the magnetic yoke 10, and corrects the difference. Includes a compensation circuit.

The angle calculation unit 46 and the position calculation unit 47 are IC circuits that calculate the magnitude of the movement amount ΔX along the X-axis direction of the magnetic yoke 10 based on the first signal S1 and the second signal S2. .. The angle calculation unit 46 calculates a change in the angle of the magnetic field line 6L based on the first signal S1 and the second signal S2. The position calculation unit 47 calculates the movement amount ΔX of the magnetic yoke 10 based on the information on the change in the angle of the magnetic field line 6L by the angle calculation unit 46, and outputs a third signal S3 including information on the movement amount ΔX to the outside. It is designed to do.

(Magnet 6)
The magnet 6 is located on the opposite side of the magnetic yoke 10 with the sensor unit 3 interposed therebetween. The magnet 6 applies a magnetic field including magnetic field lines 6L toward the magnetic yoke 10 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. 5, the magnetic field applied by the magnet 6 to the sensor unit 3 has a magnetic field line 6L in the direction along the Y axis at a position passing through the sensor unit 3. The direction of the magnetic field line 6L changes periodically due to the linear movement of the magnetic yoke 10 in the X-axis direction. When the magnetic yoke 10 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 a direction along the Y axis substantially orthogonal to the moving direction of the magnetic yoke 10. .. The direction along the Y-axis here is not limited to a direction that is completely parallel to the Y-axis, that is, 0 °, and means, for example, a direction that forms an angle of ± 30 ° or less with respect to the Y-axis. 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 Y axis, for example, but it may be tilted at an angle of ± 30 ° or less with the 0 ° as the center. Further, the larger the amplitude in the direction of the fluctuating magnetic field lines 6L is, the better, but it is substantially about ± 5 °. Here, in a state where the recess 11U of the magnetic yoke 10 is closest to the magnet 6, the direction of the magnetic field line 6L substantially coincides with the Y-axis direction at the position where it passes through the sensor unit 3. The magnetizing direction J6 of the magnet 6 may substantially coincide with, for example, the Y-axis direction.

[Operation and operation of position detection system 1]
In the position detection system 1 of the present embodiment, the movement amount ΔX of the magnetic yoke 10 in the X-axis direction can be detected by the detection module 2 including the sensor unit 3, the calculation circuit 4, and the magnet 6.

In the position detection system 1, as the magnetic yoke 10 moves straight along the X-axis direction, the convex portion 11T of the magnetic yoke 10 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. 8A, when the convex portion 11T of the magnetic yoke 10 is close to the magnet 6, the magnetic field line 6L1 generated by the magnet 6 is slightly tilted with respect to the Y-axis direction. It has a vector V1. On the other hand, when the convex portion 11T of the magnetic yoke 10 is away from the magnet 6, that is, when the concave portion 11U is close to the magnet 6, the magnetic field line 6L0 generated by the magnet 6 is substantially in the Y-axis direction. It has a matching vector V0. Therefore, as the magnetic yoke 10 moves straight along the X-axis direction, that is, with the continuous change in the relative position of the convex portion 11T with respect to the magnet 6, as shown in FIG. 8B, the vector V of the magnetic field line 6L becomes Precession will be carried out. In FIG. 8B, the convex portion T moves in the order of the convex portion 11T1, the convex portion 11T2, and the convex portion 11T3. At this time, the cycle of approaching the convex portion 11T 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 outputs a first signal S1 and a second signal S2 containing the component Bx along the X-axis direction and the component Bz along the Z-axis direction, respectively. Using the first signal S1 and the second signal S2, the movement amount ΔX of the magnetic yoke 10 and the absolute position in the X-axis direction can be obtained by the arithmetic circuit 4.

[Effect of position detection system 1]
As described above, according to the position detection system 1 of the present embodiment, the magnetic yoke 10 can move linearly with respect to the sensor unit 3 and the magnet 6 along the X-axis direction, and the first distance D1 from the magnet 6 can be moved. It has an outer edge 11 including a convex portion 11T located in the magnet 6 and a concave portion 11U located at a second distance D2 from the magnet 6. 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 movement of the magnetic yoke 10. Here, the vector V of the magnetic field line 6L at the position where the magnetic field line 6L passes through the sensor unit 3 is oriented in the Y-axis direction substantially orthogonal to the X-axis direction which is the moving direction of the magnetic yoke 10. Therefore, it is possible to suppress the influence of the accuracy of the relative positions of the magnetic yoke 10, 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 position detection system 1 of the present embodiment, the movement amount of the magnetic yoke 10 and the absolute position of the magnetic yoke 10 can be accurately obtained even when the size is reduced.

However, for example, as in the position detection system as a reference example shown in FIGS. 16A to 16C, the magnet 1006 is along the Z-axis direction in which the magnet 1006 and the outer edge 1011 of the magnetic yoke 1010 face each other. When the magnetic field lines 1006L are generated, the relative positions of the magnetic yoke 1010, the sensor unit 1003, and the magnet 1006 have a great influence on the detection accuracy of the sensor unit 1003. Specifically, when the relative positions of the magnetic yoke 1010, the sensor unit 1003, and the magnet 1006 are appropriate, as shown in FIG. 14B, the waveform of the first signal S1001 and the second signal S1001 The waveform of signal S1002 is good. However, when the relative positions of the magnetic yoke 1010, the sensor unit 1003, and the magnet 1006 are slightly displaced in the Z-axis direction, the waveform of the first signal S1001 is distorted, for example, as shown in FIG. 14 (A). Or, as shown in FIG. 14C, the waveform of the second signal S1002 is distorted. Further, in the position detection system of such a reference example, the detection accuracy tends to decrease due to the deviation of the relative position of the magnetic yoke 1010 in the Z-axis direction.

On the other hand, according to the position detection system 1 of the present embodiment, the allowable range of the relative positions of the magnetic yoke 10, the sensor unit 3, and the magnet 6 is wider than that of the position detection system as the reference example. Therefore, even when the size is reduced, it is easy to avoid a decrease in position detection accuracy due to a deviation in the arrangement position of the magnetic yoke 10, the sensor unit 3, and the magnet 6.

Further, according to the position detection system 1 of the present embodiment, the magnetic yoke 10 is fixed to the moving body as the object to be measured and the magnetic yoke 10 is moved, so that the magnet is moved, for example. Magnetic powder such as iron powder does not easily adhere to the magnet. If magnetic powder adheres to the magnet, it affects the direction of the magnetic field lines formed by the magnet, and there is a concern that the detection accuracy in the sensor unit may deteriorate. According to the position detection system 1 of the present embodiment, since it is not necessary to move the magnet 6, it can be installed inside the detection module 2 and it is possible to prevent magnetic powder from adhering to the magnet 6. Therefore, it is possible to eliminate the concern that the detection accuracy deteriorates due to the adhesion of the magnetic powder to the magnet 6.

Further, according to the position detection system 1 of the present embodiment, since the relative position between the sensor unit 3 and the magnet 6 is held constant, the minimum operating magnetic field strength required for the sensor unit 3 is stable. The sensor unit 3 is excellent in operational stability.

Further, according to the position detection system 1 of the present embodiment, since the magnet 6 does not move with respect to the sensor unit 3, that is, the distance between the sensor unit 3 and the magnet 6 is constant, the moving object as the object to be measured. The detection sensitivity of the sensor unit 3 does not decrease depending on the moving range of the sensor unit 3. When the moving range of the moving body as the object to be measured is wide, it can be dealt with by enlarging the movable length L10 (FIG. 3) of the magnetic yoke 10 in the X-axis direction. The movable length L10 in the X-axis direction can be adjusted by changing the uneven shape (period in the X-axis direction) of the magnetic yoke 10.

<2. Second Embodiment>
Next, the configuration of the position detection system 1A as the second embodiment of the present invention will be described with reference to FIGS. 9A and 9B. The position detection system 1 of the first embodiment is provided with one magnet 6 for one magnetic yoke 10 and one sensor unit 3. On the other hand, in the position detection system 1A of the second embodiment, as shown in FIGS. 9A and 9B, two magnetic yokes 10 and 20 magnetic yokes 20 are provided for one sensor unit 3 and one magnet 6. Is arranged. That is, the position detection system 1A forms a magnetic field with one magnet 6 and detects the positions of the two magnetic yokes 10 and 20 that move linearly in synchronization in the X-axis direction. Except for this point, the position detection system 1A has substantially the same configuration as the position detection system 1 of the first embodiment. FIG. 9A is a perspective view showing two magnetic yokes 10 and 20 and a magnet 6 in the position detection system 1A, and FIG. 9B shows two magnetic yokes 10 and 20 and a sensor unit 3 in the position detection system 1A. It is a front view showing the magnet 6. The position detection system 1A is a specific example corresponding to the "position detection system" of the present invention, and the magnetic yoke 20 is a specific example corresponding to the "second soft ferromagnet" of the present invention.

As shown in FIGS. 9A and 9B, in the position detection system 1A, the magnetic yoke 10 and the magnetic yoke 20 are arranged so as to face each other in the Y-axis direction. The magnetic yoke 20 is a plate-shaped member that extends along the X-axis direction so as to be parallel to the magnetic yoke 10 and has a thickness in the Y-axis direction. The magnetic yoke 20 is provided so as to be able to move straight in the + X direction and the −X direction in synchronization with the magnetic yoke 10 with respect to the detection module 2 including the magnet 6. The magnetic yoke 20 is fixed to a moving body common to the magnetic yoke 10.

The magnetic yoke 20 has an outer edge 12 facing the sensor unit 3 and the magnet 6 in the detection module 2 in the Z-axis direction. The outer edge 12 is located at a distance of 12D (FIG. 9A) from, for example, the magnet 6 in the Z-axis direction. Here, the outer edge 12 is not flat and has a concave-convex shape including, for example, a convex portion 12T and a concave portion 12U, similarly to the outer edge 11 of the magnetic yoke 10. More specifically, the outer edge 12 has a shape in which the distance 12D from the magnet 6 in the Z-axis direction periodically fluctuates in the X-axis direction so as to draw a sinusoidal curve, that is, a continuous curved surface. The convex portion 12T is a third outer edge portion at a third distance D3 from the magnet 6 in the Z-axis direction. Further, the concave portion 12U is a fourth outer edge portion located at a position different from the convex portion 12T in the X-axis direction and at a fourth distance D4 from the magnet 6 in the Z-axis direction. Here, the third distance D3 is the minimum value of the distance 12D, and the fourth distance D4 is the maximum value of the distance 12D. In the position detection system 1A of the present embodiment, the first distance D1 and the third distance D3 are equal, and the second distance D2 and the fourth distance D4 are equal. Further, the length from the convex portion 12T to the concave portion 12U in the X-axis direction corresponds to the half-period length 0.5T of the sinusoidal curve drawn by the outer edge 12. In the position detection system 1A of the present embodiment, one cycle of the sine curve drawn by the outer edge 11 and one cycle of the sine curve drawn by the outer edge 12 are equal to each other (1T). However, as shown in FIG. 9B, the phase of the curve drawn by the outer edge 11 and the phase of the curve drawn by the outer edge 12 are different by 0.5 period (0.5T).

Like the magnetic yoke 10, the magnetic yoke 20 contains a soft ferromagnet such as permalloy as a main component.

The magnetic yoke 10 and the magnetic yoke 20 can bring about a periodic change of the magnetic field line 6L of the magnetic field from the magnet 6 applied to the sensor unit 3 by the integral movement operation along the X axis. The magnet 6 may be arranged between the magnetic yoke 10 and the magnetic yoke 20 in the Y-axis direction, as shown in FIGS. 10 to 12 described later.

Subsequently, with reference to FIGS. 10 to 13, changes in the magnetic field lines 6L during operation of the position detection system 1A shown in FIGS. 9A and the like will be described.

FIG. 10 shows a state in which the convex portion 11T of the magnetic yoke 10 and the concave portion 12U of the magnetic yoke 20 reach the central position CP3 of the sensor unit 3 in the X-axis direction in the position detection system 1A (hereinafter referred to as “first state”). .) Is represented. The position of the magnetic yokes 10 and 20 in the first state of FIG. 10 is defined as the reference position 0T.

In FIG. 11, in the position detection system 1A, the midpoint in the X-axis direction between the convex portion 11T and the concave portion 11U, that is, the midpoint in the X-axis direction between the convex portion 12T and the concave portion 12U is located at the center position CP3 of the sensor unit 3. It represents the reached state (hereinafter referred to as "second state"). The movement amount ΔX of the magnetic yokes 10 and 20 in the second state of FIG. 11 is 0.25T (1/4 period).

FIG. 12 shows a state in which the concave portion 11U of the magnetic yoke 10 and the convex portion 12T of the magnetic yoke 20 reach the central position CP3 of the sensor unit 3 in the X-axis direction in the position detection system 1A (hereinafter referred to as “third state”). .) Is represented. The movement amount ΔX of the magnetic yokes 10 and 20 in the third state of FIG. 12 is 0.5 T (1/2 cycle).

(A), (B) and (C) of FIG. 10 are a front view, a top view and a top view showing the magnetic yokes 10 and 20, the sensor unit 3 and the magnet 6 of the position detection system 1A in the first state, respectively. It is a side view.

11 (A), (B) and (C) are front views, top views and top views showing the magnetic yokes 10 and 20, the sensor unit 3 and the magnet 6 of the position detection system 1A in the second state, respectively. It is a side view.

(A), (B) and (C) of FIG. 12 are a front view, a top view and a top view showing the magnetic yokes 10 and 20, the sensor unit 3 and the magnet 6 of the position detection system 1A in the third state, respectively. It is a side view.

Further, FIG. 13A is a characteristic diagram showing the relationship between the component Bx of the magnetic field line 6L detected by the sensor unit 3 and the movement amount ΔX of the magnetic yokes 10 and 20 in the X-axis direction. Further, FIG. 13B is a characteristic diagram showing the relationship between the component Bz of the magnetic field line 6L detected by the sensor unit 3 and the movement amount ΔX of the magnetic yokes 10 and 20 in the X-axis direction.

As shown in FIG. 10, in the first state, the vector V0 of the magnetic field line 6L passing through the sensor unit 3 does not include the component Bx in the X-axis direction, and only the component By in the Y-axis direction and the component Bz in the Z-axis direction. including. However, in the first state, the component Bz of the vector V0 is in the + Z direction. Therefore, as shown in FIG. 13, the component Bx becomes 0 at the reference position of the movement amount ΔX = 0T. On the other hand, at the reference position of the movement amount ΔX = 0T, the component Bz has the maximum value HZ.

As shown in FIG. 11, in the second state in which the magnetic yokes 10 and 20 have moved 0.25 T in the + X direction from the first state, the vector V0.25 of the magnetic field line 6L passing through the sensor unit 3 is in the Z-axis direction. The component Bz of the above is not included, and only the component Bx in the X-axis direction and the component By in the Y-axis direction are included. However, in the second state, the component Bx of the vector V0.25 is in the + X direction. Therefore, as shown in FIG. 13, at the position of the movement amount ΔX = 0.25T, the component Bx becomes the maximum value HX and the component Bz becomes 0.

As shown in FIG. 12, in the third state in which the magnetic yokes 10 and 20 have moved 0.5 T in the + X direction from the first state, the magnetic field lines passing through the sensor unit 3 are the same as in the first state of FIG. The vector V0.5 of 6L does not include the component Bx in the X-axis direction, but contains only the component By in the Y-axis direction and the component Bz in the Z-axis direction. However, in the first state of FIG. 10, the component Bz of the vector V0 is in the + Z direction, whereas in the third state of FIG. 12, the component Bz of the vector V0.5 is in the −Z direction. Therefore, as shown in FIG. 13, at the position of the movement amount ΔX = 0.5T, the component Bx becomes 0 and the component Bz becomes the minimum value LZ.

As described above, also in the position detection system 1A of the second embodiment, the magnetic yoke 10, using the first signal S1 and the second signal S2 including the change of the component Bx and the change of the component Bz, respectively, The amount of movement ΔX along the X-axis direction of 20 can be obtained. Therefore, the same effect as that of the position detection system 1 of the first embodiment can be expected.

Moreover, since the position detection system 1A of the second embodiment has two magnetic yokes 10 and 20s adjacent to each other in the Y-axis direction orthogonal to the X-axis direction which is the moving direction, the first. The influence of the positional deviation of the sensor unit 3 and the magnet 6 in the Y-axis direction on the detection accuracy is further reduced as compared with the embodiment of. This is the amplitude of the component Bx along the X-axis direction, which is the moving direction in the magnetic field generated from the magnet 6, and the Bz along the Z-axis direction in the magnetic field generated from the magnet 6, as compared with the case of one magnetic yoke. This is because the amplitudes of the components are doubled and the S / N ratio is improved.

Further, by arranging the sensor unit 3 between the magnetic yoke 10 and the magnetic yoke 20, for example, when the sensor unit 3 is displaced in the direction away from the magnetic yoke 10 along the Y-axis direction, the sensor unit 3 is inevitable. The magnetic yoke 20 approaches the magnetic yoke 20 along the Y-axis direction. Therefore, even if the magnetic flux density of the magnetic field extending to the sensor unit 3 decreases as the distance from the magnetic yoke 10 decreases, the magnetic flux density of the magnetic field extending to the sensor unit 3 is complemented by the magnetic yoke 20 approaching the sensor unit 3. It becomes. Therefore, according to the position detection system 1A 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 magnetic yokes 10 and 20 in the Y-axis direction.

<3. Third Embodiment>
Next, the configuration of the position detection system 1B as the third embodiment of the present invention will be described with reference to FIGS. 14A to 14C. The position detection system 1A of the second embodiment is provided with one magnet 6 for two magnetic yokes 10 and 20 and one sensor unit 3. On the other hand, in the position detection system 1B of the third embodiment, as shown in FIGS. 14A and 14B, two magnetic yokes 10 and two magnetic yokes 20 and two magnets 6A are provided for one sensor unit 3. And the magnet 6B is arranged. That is, the position detection system 1B forms a magnetic field by the two magnets 6A and 6B, and detects the positions of the two magnetic yokes 10 and 20 that move linearly in synchronization in the X-axis direction. Except for this point, the position detection system 1B has substantially the same configuration as the position detection system 1A of the second embodiment. FIG. 14A is a perspective view showing two magnetic yokes 10 and 20 and two magnets 6A and 6B in the position detection system 1B, and FIG. 14B is a perspective view showing two magnetic yokes 10 and 20 in the position detection system 1B. , Is a front view showing the sensor unit 3 and the two magnets 6A and 6B. Further, FIG. 14C is a perspective view showing the sensor unit 3 and the two magnets 6A and 6B in the position detection system 1B. The position detection system 1B is a specific example corresponding to the "position detection system" of the present invention, and the magnet 6A and the magnet 6B correspond to the "first magnet" and the "second magnet" of the present invention, respectively. This is a concrete example of how to do it.

As shown in FIGS. 14A and 14B, in the position detection system 1B, the magnets 6A and 6B are arranged so as to be spaced apart from each other along the X-axis direction in which the magnetic yokes 10 and 20 move. The sensor unit 3 is arranged between the magnet 6A and the magnet 6B in the X-axis direction, and the magnet 6A, the magnet 6B, and the magnetic yoke 10 in the Z-axis direction in which the magnet 6A and the magnet 6B and the magnetic yokes 10 and 20 face each other. It is arranged between 20 and 20. As shown in FIG. 14C, both the magnet 6A and the magnet 6B are magnetized along the Y-axis direction, and generate a magnetic field including the magnetic field line 6AL and the magnetic field line 6BL, respectively. The magnetic field lines 6AL and the magnetic field lines 6BL each have vectors that are substantially parallel to each other in the direction along the Y-axis at the position where they pass through the sensor unit 3.

The magnet 6A and the magnet 6B may be arranged between the magnetic yoke 10 and the magnetic yoke 20 in the Y-axis direction.

As described above, the position detection system 1B of the third embodiment can be expected to have the same effect as the position detection system 1 of the first embodiment and the position detection system 1A of the second embodiment. .. Further, in the position detection system 1B of the third 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 field lines 6BL pass through the sensor unit 3. The magnetic field line 6AL and the magnetic field line 6BL are made to have a vector in the direction along the Y axis. Therefore, an unstable region in which the magnetic field line 6AL and the magnetic field line 6BL repel each other is generated in the vicinity of the sensor unit 3, and when the convex portion 11T of the magnetic yoke 10 passes in the vicinity of the unstable region, for example, the vector of the magnetic field line 6AL The direction and the direction of the vector of the field line 6BL will change sensitively. Therefore, in the position detection system 1B of the third embodiment, the output in the sensor unit 3 is larger than that of the position detection system 1 of the first embodiment and the position detection system 1A of the second embodiment. Change is obtained.

<4. 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 each of the above embodiments, the outer edges of the first soft ferromagnet and the second soft ferromagnet are curved so as to draw a sinusoidal curve, but the present invention is limited to this. Not done. For example, it may be a rectangular outer edge.

Further, in the third embodiment, two magnetic yokes and two magnets are arranged for one sensor unit. For example, one magnetic yoke and two magnets are arranged for one sensor unit. And may be arranged.

Further, in each drawing in each of the above-described embodiments, the outer edge of one magnetic yoke has one convex portion and one concave portion, but the present invention is not limited thereto. For example, as in the position detection system 1C as a modification shown in FIG. 15, the outer edges 11 and 12 of the magnetic yokes 10C and 20C are repeatedly arranged with a plurality of convex portions and a plurality of concave portions alternately in the X-axis direction. It may be what is done.

Further, the movable length of the magnetic yoke in the X-axis direction may be longer than the length of one cycle in the X-axis direction of the outer edge thereof.

Further, in the above-described embodiment and the like, the magnetic detection unit is provided with two magnetic detection elements, 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. You may be prepared. 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 of 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 is in close proximity to a first magnetic detector having a first detection axis and a second magnetic detector having a second detection axis orthogonal to the first detection axis. A plurality of arranged magnetic detector element pairs may be provided. When the above-mentioned two-axis magnetic detection elements are arranged at a plurality of locations and when the above-mentioned magnetic detection element pairs are arranged at a plurality of locations, the arrangement pitch thereof is in the moving direction of the soft ferromagnet. For example, it is desirable that it matches the arrangement pitch of the convex portion of the soft ferromagnet.

1,1A to 1C ... Position detection system, 10,20 ... Magnetic yoke, 11,12 ... Outer edge, 11T, 12T ... Convex part, 11U, 12U ... Concave part, 2 ... Detection module, 3 ... Sensor part, 31,32 ... Magnetic sensor, 4 ... calculation circuit, 46 ... angle calculation unit, 47 ... position calculation unit, 6, 6A, 6B ... magnet, 6L ... magnetic field lines, 7 ... substrate.

Claims (14)

A first magnet having a magnetized magnetism in the first direction and forming a first magnetic field containing a first field line,
It extends along a second direction orthogonal to the first direction, can move straight along the second direction with respect to the first magnet, and can move straight along the first direction and the second direction. The third outer edge portion at a first distance from the first magnet in a third direction orthogonal to both directions and a position different from the first outer edge portion in the second direction. A first soft ferromagnetic material having a first outer edge having a concavo-convex shape including a second outer edge portion at a second distance from the first magnet in the direction of
The magnetism provided so that the first magnetic field line passes through itself in the first direction while the relative position with respect to the first magnet is maintained constant and the first soft ferromagnet is stationary. a detection unit,
Arranged so as to face the first soft ferromagnet in the first direction, extend along the second direction, and with respect to the first magnet, said in the second direction. It can move straight in synchronization with the first soft ferromagnet, and has a third outer edge portion at a third distance from the first magnet in the third direction and the third in the second direction. A second soft ferromagnetism having a second outer edge having a concavo-convex shape including a fourth outer edge portion at a position different from the outer edge portion of the magnet and at a fourth distance from the first magnet in the third direction. With the body
With
The first outer edge of the first soft ferromagnet periodically fluctuates in the second direction with the first length as one cycle in the distance from the first magnet in the third direction. Has a shape to
The second outer edge of the second soft ferromagnet periodically has a distance from the first magnet in the third direction with the first length as one cycle in the second direction. Has a fluctuating shape
A position detection system in which the phase of the first outer edge and the phase of the second outer edge are different by 0.5 period. The first aspect of the first soft ferromagnet has a shape in which the distance from the first magnet in the third direction periodically fluctuates in the second direction. Position detection system. The position detection system according to claim 2, wherein the movable length of the first soft ferromagnet in the second direction is equal to or less than the length of one cycle in the second direction of the first outer edge. .. The position detection system according to claim 2 or 3, wherein the first outer edge includes a continuous first curve. The position according to any one of claims 1 to 4, wherein the magnetic detector is provided between the first magnet and the first soft ferromagnet in the third direction. Detection system. The first center position of the magnetic detector in the first direction and the second center position of the first soft ferromagnet in the first direction are different in the first direction. The position detection system according to any one of claims 1 to 5. The first outer edge includes a continuous first curved surface, and the second outer edge includes a continuous second curved surface.
The position detection system according to any one of claims 1 to 6. As the first soft ferromagnet moves in the second direction, the direction of the first magnetic field line fluctuates periodically.
The position detection system according to any one of claims 1 to 7 , wherein the magnetic detector detects the direction of the first magnetic field line that fluctuates periodically. A first magnet having a magnetized magnetism in the first direction and forming a first magnetic field containing a first field line,
It extends along a second direction orthogonal to the first direction, can move straight along the second direction with respect to the first magnet, and can move straight along the first direction and the second direction. The third outer edge portion at a first distance from the first magnet in a third direction orthogonal to both directions and a position different from the first outer edge portion in the second direction. A first soft ferromagnetic material having a first outer edge having a concavo-convex shape including a second outer edge portion at a second distance from the first magnet in the direction of
The magnetism provided so that the first magnetic field line passes through itself in the first direction while the relative position with respect to the first magnet is maintained constant and the first soft ferromagnet is stationary. With the detector
To said magnetic detection unit, and a second magnet forming a second magnetic field including the second magnetic force lines passing through the magnetic detection portion in the first direction
Position detection system comprising a. The magnetic detection unit, the first soft between the ferromagnetic member and the first magnet or the first claim is disposed between the soft ferromagnetic body and the second magnet 9, The described position detection system. The position detection system according to claim 9 or 10 , wherein the first magnet and the second magnet are adjacent to each other in the second direction. The position detection system according to claim 11 , wherein the magnetic detection unit is arranged between the first magnet and the second magnet in the second direction. 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 position detection system according to any one of claims 12. 13. The position detection system according to claim 13, wherein the first detection axis substantially coincides with the second direction, and the second detection axis substantially coincides with the third direction.

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