JP2018200284A - Detection device and detection system - Google Patents

Abstract

To provide a detection device for accurately detecting a rotational operation of a rotator even when a magnetic field generation part generates a magnetic field having distribution.SOLUTION: A detection device for detecting a change in magnetic flux density accompanied by relative movement of a detected unit comprises: a first magnetic sensor connected between a first terminal which outputs a first detection signal and a first potential; a second magnetic sensor arranged at a position shifted from the first magnetic sensor in the relative movement direction of the detected unit or a direction opposite to the relative movement direction, and connected between the first terminal and a second potential; and a magnetic field application part for applying a magnetic field having magnetic flux density gradually increasing or decreasing in the relative movement direction to the first magnetic sensor and the second magnetic sensor.SELECTED DRAWING: Figure 15

Description

  The present invention relates to a detection device and a detection system.

Conventionally, there has been known a detection device that detects a rotational operation such as a rotational speed of a rotating body using a magnetoresistive element having a magnetic sensing portion formed of a compound semiconductor thin film (see, for example, Patent Document 1).
Patent Document 1 Japanese Patent No. 4240306

  Such a detection device is provided with a magnetic field generator such as a magnet and a plurality of magnetoresistive elements for a rotating body, and detects a change in magnetic flux density due to relative movement of the rotating body, thereby rotating the rotating body. Was accurately detected. However, since the magnetic field generator generates a magnetic field having a distribution in the moving direction of the rotating body, when the rotating body rotates, an eddy current is generated by electromagnetic induction according to the distribution and rotation speed, and an error is detected in the rotation detection result. It was sometimes caused.

  According to a first aspect of the present invention, there is provided a detection device for detecting a change in magnetic flux density accompanying relative movement of a unit to be detected, which is connected between a first terminal that outputs a first detection signal and a first potential. A first magnetic sensor and a second magnet connected between the first terminal and the second potential, and disposed at a position shifted from the first magnetic sensor in a relative movement direction of the detected unit or in a direction opposite to the relative movement direction. A detection device is provided that includes a sensor and a magnetic field application unit that applies a magnetic field in which the magnetic flux density gradually increases or decreases in the relative movement direction to the first magnetic sensor and the second magnetic sensor.

  According to a second aspect of the present invention, there is provided a detection system comprising a detected unit and the detection device of the first aspect provided to face the detected unit.

  The above summary of the present invention does not enumerate all of the features of the present invention. A sub-combination of these feature groups can also be an invention.

The structural example of the detection system 100 which detects rotation operation of the rotary body 10 is shown. 2 shows a more detailed configuration example of the detection system 100 shown in FIG. The structural example of the detection system 100 when the rotary body 10 shown in FIG. 2 moves to a moving direction is shown. The structural example of the detection system 100 when the rotary body 10 shown in FIG. 3 moves to a moving direction is shown. An example of the detection signal which the detection apparatus 110 outputs is shown. The structural example of the detection apparatus 110 is shown. The modification of the detection apparatus 110 is shown. An example of the amplifier circuit 530 corresponding to the detection apparatus 110 of the modification shown in FIG. 7 is shown. The structural example of the detection system 100 provided with the detection apparatus 110 of the modification shown in FIG. 7 is shown. The 1st structural example of the detection apparatus 110 which concerns on this embodiment is shown. The modification of the detection apparatus 110 which concerns on this embodiment is shown. An example in which the magnetic field generation unit 20 according to the present embodiment generates a magnetic field having a magnetic flux density distribution is shown. An example of the offset voltage superimposed on the detection result of the detection apparatus 110 which concerns on this embodiment is shown. An example in which an offset voltage is superimposed on a detection signal output from the detection device 110 is shown. The detection system 100 provided with the 2nd structural example of the detection apparatus 110 which concerns on this embodiment is shown. An example of the relationship between the magnetic flux input into the 1st magnetoresistive element 212 and the 2nd magnetoresistive element 214 which concern on this embodiment, and resistance value is shown. The detection system 100 provided with the 3rd structural example of the detection apparatus 110 which concerns on this embodiment is shown. The 3rd structural example of the detection apparatus 110 which concerns on this embodiment is shown. The 4th structural example of the detection apparatus 110 which concerns on this embodiment is shown. The detection system 100 provided with the 4th structural example of the detection apparatus 110 which concerns on this embodiment is shown. The detection system 100 provided with the 5th structural example of the detection apparatus 110 which concerns on this embodiment is shown. The 5th structural example of the detection apparatus 110 which concerns on this embodiment is shown. The 6th structural example of the detection apparatus 110 which concerns on this embodiment is shown.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 shows a configuration example of a detection system 100 that detects the rotation operation of the rotating body 10. The detection system 100 detects, for example, a rotation operation such as the rotation speed, rotation direction, and rotation speed of the rotating body 10. The detection system 100 arranges a detection device 110 having a magnetoresistive element between the rotating body 10 and the magnet, and detects the rotational operation of the rotating body 10 according to a change in the resistance of the magnetoresistive element. In the present embodiment, the magnetoresistive element is an example of a magnetic sensor. The detection system 100 includes a rotating body 10, a magnetic field generation unit 20, and a detection device 110.

  The rotating body 10 has a convex part and / or a concave part, and rotates around a rotation axis. The rotating body 10 has, for example, a circular cross-sectional shape that is substantially orthogonal to the rotation axis. Further, a part of the cross-sectional shape of the rotating body 10 may be circular. The rotating body 10 is a gear such as a gear, for example. FIG. 1 shows an example in which a rotating body 10 has a disk shape, and concave portions and convex portions are alternately arranged along the rotational movement direction on the circumference of the disk.

  The magnetic field generator 20 generates a predetermined substantially constant magnetic field. The magnetic field generation unit 20 has, for example, a magnet and is arranged so that the N pole or the S pole faces the direction of the rotating body 10. The magnetic field generator 20 is provided on the detection device 110 on the side opposite to the rotating body 10. The magnetic field generation unit 20 is arranged close to the rotating body 10 so that the generated magnetic field reaches the convex portion and / or the concave portion of the rotating body 10. As an example, the magnetic field generation unit 20 is a permanent magnet including a material such as ferrite, samarium cobalt, and neodymium.

  The detection device 110 is provided between the rotator 10 and the magnetic field generator 20 and faces a convex portion and / or a concave portion of the rotator 10. The detection device 110 detects a magnetic flux density that is generated from the magnetic field generation unit 20 and changes at the convex portion and / or the concave portion of the rotating body 10. The detection device 110 detects the rotation operation of the rotating body 10 based on the magnetic flux density that changes according to the rotation of the rotating body 10. Details of such a detection system 100 will be described next.

  FIG. 2 shows a more detailed configuration example of the detection system 100 shown in FIG. In the detection system 100 of FIG. 2, the same reference numerals are given to the substantially same operations as those of the detection system 100 shown in FIG. In FIG. 2, the moving direction of the rotating body 10 is indicated by an arrow. FIG. 2 shows an example in which the detection system 100 further includes a power supply 40.

  The power supply 40 has one terminal of the first potential and the other terminal of the second potential, and supplies the potential difference between the first potential and the second potential to the detection device 110 as a power supply voltage. FIG. 2 shows an example in which the first potential is higher than the second potential. The second potential may be a ground potential (ground potential).

  FIG. 2 shows the first tooth 12 and the second tooth 14 which are part of the gear of the rotating body 10. FIG. 2 shows an example in which the detection device 110 includes a first bridge magnetoresistive element 210, a first terminal 250, a third bridge magnetoresistive element 310, and a third terminal 350.

  The first bridge magnetoresistive element 210 and the third bridge magnetoresistive element 310 detect a change in magnetic flux density accompanying the relative movement of the rotating body 10. 1 and 2 shows an example in which the magnetic field generator 20 and the detection device 110 are fixed and the rotating body 10 rotates. That is, the relative movement of the rotating body 10 is the movement of the rotating body 10 in the circumferential direction. One of the first bridge magnetoresistive element 210 and the third bridge magnetoresistive element 310 may detect the rotational speed and the rotational speed of the rotating body 10. Further, the rotation direction of the rotating body 10 may be detected using the first bridge magnetoresistive element 210 and the third bridge magnetoresistive element 310.

  The first terminal 250 and the third terminal 350 output detection results. The first bridge magnetoresistive element 210 and the third bridge magnetoresistive element 310 receive a power supply voltage from the power supply 40. The first bridge magnetoresistive element 210 includes a first magnetoresistive element 212 and a second magnetoresistive element 214. The first magnetoresistive element 212 is connected between the first terminal 250 and the first potential of the power supply 40. The second magnetoresistive element 214 is connected between the first terminal 250 and the second potential of the power supply 40. That is, the first magnetoresistive element 212 and the second magnetoresistive element 214 are connected to the power supply 40 in series. In this case, the first terminal 250 outputs a voltage obtained by dividing the power supply voltage by the first magnetoresistive element 212 and the second magnetoresistive element 214.

  The magnetoresistive elements such as the first magnetoresistive element 212 and the second magnetoresistive element 214 change the resistance value according to the magnetic flux density accompanying the relative movement of the rotating body 10 from the magnetic field generator 20. For example, the magnetoresistive element is a semiconductor magnetoresistive element, for example, whose resistance value increases as the magnetic flux density of the input magnetic field increases. A semiconductor magnetoresistive element is a semiconductor magnetoresistive element containing a III-V group semiconductor material as an example.

  The first magnetoresistive element 212 and the second magnetoresistive element 214 are arranged along the moving direction of the rotating body 10. The first magnetoresistive element 212 and the second magnetoresistive element 214 may be arranged according to the period of the convex part and / or the concave part of the rotating body 10. For example, as shown in FIG. 2, when the second magnetoresistive element 214 is opposed to the first tooth 12 that is the convex portion of the rotating body 10, the first magnetoresistive element 212 is the first tooth 12 and the second tooth 12. The first magnetoresistive element 212 and the second magnetoresistive element 214 are arranged so as to face each other between the teeth 14. In addition, between the 1st tooth | gear 12 and the 2nd tooth | gear 14 is the recessed part of the rotary body 10, or the intermediate part of two convex parts.

  Since the magnetic field generator 20 faces the rotating body 10, the distance between the first tooth 12 and the magnetic field generator 20 in FIG. 2 can be the minimum distance between the rotating body 10 and the magnetic field generator 20. That is, the region between the tooth surface of the tooth tip perpendicular to the axial direction of the first tooth 12 and the magnetic field generator 20 is a region having the maximum value among changes in magnetic flux density. Here, the tooth surface of the tooth tip is the tooth tip surface. Therefore, as shown in the example of FIG. 2, when the second magnetoresistive element 214 is located in the region, the resistance value of the second magnetoresistive element 214 is within a range in which the resistance value changes according to the input magnetic flux density. Maximum value.

  Further, the distance between the concave portion of the rotator 10 and the magnetic field generator 20 is larger than the distance between the rotator 10 and the magnetic field generator 20. That is, the region between the tooth tip surface perpendicular to the axial direction of the first tooth 12 and the magnetic field generation unit 20 is a region that can be the minimum value among changes in magnetic flux density. That is, when the first magnetoresistive element 212 is located in the region, the resistance value of the first magnetoresistive element 212 becomes the minimum value in a range in which the resistance value changes according to the input magnetic flux density. Therefore, at the position of the rotating body 10 as shown in the example of FIG. 2, the detection device 110 outputs the maximum value in the voltage change range obtained by dividing the power supply voltage from the first terminal 250.

  Similar to the first bridge magnetoresistive element 210, the third bridge magnetoresistive element 310 includes a fifth magnetoresistive element 312 and a sixth magnetoresistive element 314. The fifth magnetoresistive element 312 is connected between the third terminal 350 and the first potential of the power supply 40. The sixth magnetoresistive element 314 is connected between the third terminal 350 and the second potential of the power supply 40. That is, the fifth magnetoresistive element 312 and the sixth magnetoresistive element 314 are connected to the power supply 40 in series. In this case, the third terminal 350 outputs a voltage obtained by dividing the power supply voltage by the fifth magnetoresistive element 312 and the sixth magnetoresistive element 314.

  The fifth magnetoresistive element 312 and the sixth magnetoresistive element 314 are arranged along the moving direction of the rotating body 10 in accordance with the period of the protrusions and / or recesses periodically arranged in the rotating body 10. The fifth magnetoresistive element 312 and the sixth magnetoresistive element 314 are arranged at positions different from the first magnetoresistive element 212 and the second magnetoresistive element 214 in the moving direction of the rotating body 10, respectively.

  For example, the fifth magnetoresistance element 312 is provided between the first magnetoresistance element 212 and the second magnetoresistance element 214 in the moving direction of the rotating body 10. That is, in FIG. 2, the fifth magnetoresistive element 312 is located between the convex portion and the concave portion of the rotating body 10. The sixth magnetoresistive element 314 is provided so as to sandwich the fifth magnetoresistive element 312 and the second magnetoresistive element 214. That is, in FIG. 2, the sixth magnetoresistive element 314 is also located between the convex portion and the concave portion of the rotating body 10.

  Therefore, the magnetic flux density of the fifth magnetoresistive element 312 and the sixth magnetoresistive element 314 is an intermediate magnetic flux density between the magnetic flux densities of the first magnetoresistive element 212 and the second magnetoresistive element 214. For example, when the first magnetoresistive element 212, the fifth magnetoresistive element 312, the second magnetoresistive element 214, and the sixth magnetoresistive element 314 are arranged at equal intervals in the moving direction of the rotating body 10, The resistance values of the magnetoresistive element 312 and the sixth magnetoresistive element 314 are substantially in the middle of the resistance value change range.

  The first magnetoresistive element 212, the fifth magnetoresistive element 312, the second magnetoresistive element 214, and the sixth magnetoresistive element 314 have substantially the same initial resistance value and substantially the same resistance with respect to the magnetic flux density. A magnetoresistive element having a change rate was obtained. Thereby, at the position of the rotating body 10 as shown in the example of FIG. 2, the detection device 110 outputs the intermediate value of the power supply voltage from the third terminal 350. Since the rotating body 10 moves in the moving direction of the arrow shown in FIG. 2 with respect to such a detection device 110, the magnetic flux density input to each magnetoresistive element is the position of the convex portion and / or the concave portion of the rotating body 10. The voltage output from the first terminal 250 and the third terminal 350 is also increased or decreased.

  FIG. 3 shows a configuration example of the detection system 100 when the rotating body 10 shown in FIG. 2 moves in the moving direction. In the detection system 100 of FIG. 3, the same reference numerals are given to the substantially same operations as those of the detection system 100 shown in FIG. FIG. 3 shows an example in which the rotating body 10 has moved to a position where the fifth magnetoresistive element 312 faces the concave portion and the sixth magnetoresistive element 314 faces the first tooth 12 that is a convex portion.

  That is, the resistance value of the fifth magnetoresistive element 312 has a minimum value, and the resistance value of the sixth magnetoresistive element 314 has a maximum value. Therefore, at the position of the rotating body 10 as shown in the example of FIG. 3, the detection device 110 outputs from the third terminal 350 the maximum value in the voltage change range obtained by dividing the power supply voltage. That is, the detection device 110 outputs a voltage substantially the same as the voltage output from the first terminal 250 in the example of FIG. 2 from the third terminal 350 in the example of FIG.

  In FIG. 3, the first magnetoresistive element 212 and the second magnetoresistive element 214 are respectively positioned between the convex part and the concave part of the rotating body 10. That is, the resistance values of the first magnetoresistive element 212 and the second magnetoresistive element 214 are each approximately in the middle of the resistance value change range. Therefore, at the position of the rotating body 10 as shown in the example of FIG. 3, the detection device 110 outputs an intermediate value of the power supply voltage from the first terminal 250.

  FIG. 4 shows a configuration example of the detection system 100 when the rotating body 10 shown in FIG. 3 moves in the movement direction. In the detection system 100 of FIG. 4, the same reference numerals are given to substantially the same operations as those of the detection system 100 shown in FIGS. 2 and 3, and description thereof is omitted. FIG. 4 shows an example in which the rotating body 10 is moved until the fifth magnetoresistive element 312 and the sixth magnetoresistive element 314 are respectively positioned between the convex portion and the concave portion of the rotating body 10.

  That is, the resistance values of the fifth magnetoresistive element 312 and the sixth magnetoresistive element 314 are each approximately in the middle of the resistance value change range. Therefore, at the position of the rotating body 10 as shown in the example of FIG. 4, the detection device 110 outputs an intermediate value of the power supply voltage from the third terminal 350. In other words, the detection device 110 outputs a voltage substantially the same as the voltage output from the first terminal 250 in the example of FIG. 3 from the third terminal 350 in the example of FIG.

  In FIG. 4, the first magnetoresistive element 212 faces the second teeth 14 that are convex portions, and the second magnetoresistive element 214 faces the concave portions. That is, the resistance value of the first magnetoresistive element 212 is the maximum value, and the resistance value of the second magnetoresistive element 214 is the minimum value. Therefore, at the position of the rotator 10 as shown in the example of FIG. 4, the detection device 110 outputs the minimum value in the voltage change range obtained by dividing the power supply voltage from the third terminal 350.

FIG. 5 shows an example of a detection signal output from the detection device 110. The horizontal axis of FIG. 5 indicates time t, and the vertical axis indicates the voltage value V of the detection signal. FIG. 5 shows an example in which the detection signal voltages output from the first terminal 250 and the third terminal 350 are plotted. For example, time t ₁ is an example of a point in time when the position of the rotating body 10 with respect to the detection device 110 is arranged as shown in FIG. In this case, the first terminal 250 outputs the voltage V ₁ that is the maximum value of the voltage change, and the third terminal 350 outputs the voltage V ₂ that is an intermediate value of the voltage change.

Next, at time t ₂ is an example of a time when the position with respect to the detection device 110 of the rotary body 10 is moved to the arrangement shown in FIG. 3 from FIG. In this case, the first terminal 250, the voltage V ₂ which is an intermediate value of the voltage change is output, the third terminal 350, the voltages V ₁ is the maximum value of the voltage change is outputted. Next, at time t ₃ is an example of a time when the position with respect to the detection device 110 of the rotary body 10 is moved to the arrangement shown in FIG. 4 FIG. In this case, the first terminal 250, the voltage V ₃ is the minimum value of the voltage change is output, the third terminal 350 outputs a voltage V ₂ which is an intermediate value of the voltage change.

  As described above, when the rotating body 10 moves at a constant speed around the rotation axis, the detection signals output from the first terminal 250 and the third terminal 350 are sine wave signals. Therefore, the detection device 110 can detect the rotation speed of the rotating body 10 from the period of the detection signal output from the first terminal 250 and / or the third terminal 350. Moreover, the detection apparatus 110 can detect the rotation speed of the rotary body 10 from the detection frequency, such as the peak value of a sine wave signal, for example. Even if the rotating body 10 is not at a constant speed, the detection signal changes as the tooth position is moved by rotation, so that the detection apparatus 110 causes the rotating body 10 to be Can be detected.

  Further, as shown in FIGS. 2 to 4, the first magnetoresistive element 212 becomes the magnetoresistive element that first faces the new gear teeth by the rotation of the rotating body 10, so that the first terminal 250 is detected. The phase of the signal is ahead of the detection signal of the third terminal 350. When the rotating direction of the rotating body 10 is reversed, the magnetoresistive element that first faces the teeth of the new gear by the rotation of the rotating body 10 becomes the sixth magnetoresistive element 314. Therefore, in the case of reverse rotation, the detection signal at the first terminal 250 is delayed in phase from the detection signal at the third terminal 350. Therefore, the detection device 110 can detect the rotation direction of the rotating body 10 by comparing the phases of the detection signals of the first terminal 250 and the third terminal 350.

  FIG. 6 shows a configuration example of the detection device 110. In other words, the detection device 110 includes the substrate 30, and a magnetic sensitive part or the like is formed on the substrate 30. The substrate 30 is a substrate formed of, for example, a semiconductor, glass, ceramic, or the like. The substrate 30 has a first potential terminal 202, a second potential terminal 204, a first bridge magnetoresistive element 210, a first terminal 250, a third bridge magnetoresistive element 310, and a third terminal 350 formed on the surface.

The first potential terminal 202 is connected to one terminal of the power supply 40 and is supplied with the first potential. The second potential terminal 204 is connected to the other terminal of the power supply 40 and is supplied with the second potential. The first terminal 250 outputs the detection signal V _A , and the third terminal 350 outputs the detection signal V _B having a phase different from that of the detection signal V _A.

  The magnetic sensitive parts of the first bridge magnetoresistive element 210 and the third bridge magnetoresistive element 310 are arranged in the moving direction of the rotating body 10. Here, in FIG. 6, the direction indicated by the arrow is the moving direction of the rotating body 10. The first bridge magnetoresistive element 210 and the third bridge magnetoresistive element 310 are provided on the surface of the substrate 30 that should face the rotating body 10.

  The first bridge magnetoresistive element 210 and the third bridge magnetoresistive element 310 are formed so that at least part of the range in which the magnetosensitive part is provided overlaps in the width direction orthogonal to the moving direction of the rotating body 10. That is, in the first magnetoresistive element 212, the second magnetoresistive element 214, the fifth magnetoresistive element 312, and the sixth magnetoresistive element 314, at least a part of the range in which the magnetosensitive portion is provided overlaps in the width direction.

  FIG. 6 shows an example in which each of the first magnetoresistive element 212, the second magnetoresistive element 214, the fifth magnetoresistive element 312 and the sixth magnetoresistive element 314 includes two magnetosensitive parts. Here, each of the magnetic sensitive portions is shown in a substantially rectangular shape extending in the width direction. FIG. 6 shows an example in which the magnetic sensitive parts included in the respective resistance elements are arranged at substantially equal intervals in the moving direction of the rotating body 10. As an example, FIG. 6 shows an example in which each magnetic sensing unit is arranged at a position translated in the moving direction of the rotating body 10. In this case, the first magnetoresistive element 212, the second magnetoresistive element 214, the fifth magnetoresistive element 312, and the sixth magnetoresistive element 314 are all overlapped with each other in the width direction. .

  The first magnetoresistive element 212, the second magnetoresistive element 214, the fifth magnetoresistive element 312, and the sixth magnetoresistive element 314 are arranged in the first region 512, the second region 514, the third magnetoresistive element 314 arranged at equal intervals on the substrate 30. A region 516 and a fourth region 518 are formed. The distance between the first region 512, the second region 514, the third region 516, and the fourth region 518 is ¼ of the circle pitch of the gear teeth of the rotating body 10, and between the rotating body 10 and the detection device 110. It is approximately equal to the value multiplied by the coefficient corresponding to the distance. Here, for example, if the gear tooth size is module m = d / z, the circular pitch p of the gear is p = πm. In addition, d is a reference | standard circle diameter, z is the number of teeth, and the circular pitch p is the result calculated by dividing the circumference (πd) by the number of teeth z.

  Since the plurality of resistance elements are arranged corresponding to the circular pitch of the gear in the moving direction of the rotating body 10, each resistance element faces the corresponding tooth tip surface at a corresponding time during the rotation of the gear. be able to. FIG. 6 shows the first magnetoresistive element 212 in the first region 512, the fifth magnetoresistive element 312 in the second region 514, the second magnetoresistive element 214 in the third region 516, and the sixth in the fourth region 518. The example in which the magnetoresistive element 314 was each formed is shown.

  Thereby, for example, when the rotating body 10 is rotating, at the first time point, the first magnetoresistive element 212 faces the tooth tip surface of the first tooth of the gear, and at the next second time point, The fifth magnetoresistive element 312 can face the tooth tip surface of the first tooth of the gear. In this way, the plurality of magnetoresistive elements can face the tooth tip surface of the first tooth of the gear for each region in the order in which they are arranged in the moving direction as time advances. Similarly, the plurality of magnetoresistive elements can be opposed to the recesses of the rotating body 10 for each region in the order in which they are arranged in the moving direction as time advances. Thereby, the detection device 110 can accurately detect the movement of the rotating body 10 and output the detection result as a detection signal.

  As described above, the detection system 100 can detect the rotation operation of the rotating body 10. However, noise generated from the outside or the inside may be superimposed on the detection signal output from the detection system 100. The amplitude intensity of the detection signal output from the detection system 100 is preferably larger from the viewpoint of S / N. Therefore, the detection system 100 can realize noise reduction and S / N improvement by using a differential signal as an output signal. Next, the detection apparatus 110 that outputs such a differential signal will be described.

  FIG. 7 shows a modification of the detection device 110. In the detection apparatus 110 according to the modified example of FIG. 7, the same reference numerals are given to the substantially same operations as those of the detection apparatus 110 shown in FIG. The detection device 110 according to the modified example includes a first detection unit 112 and a second detection unit 114 having substantially the same shape as the detection device 110 illustrated in FIG. That is, in the detection device 110 according to the modified example, the first detection unit 112 and the second detection unit 114 are formed on the substrate 30.

  In the detection device 110 according to the modification, one detection unit generates a positive side signal and the other detection unit generates a negative side signal and outputs the signal as a differential signal. FIG. 7 illustrates an example in which the first detection unit 112 generates a positive signal and the second detection unit 114 generates a negative signal. In this case, the first detection unit 112 has substantially the same configuration as the detection device 110 shown in FIG.

  The second detection unit 114 includes a second potential terminal 206, a first potential terminal 208, a second bridge magnetoresistive element 220, a second terminal 260, a fourth bridge magnetoresistive element 320, and a fourth terminal 360. The second potential terminal 206 is connected to the second potential terminal 204 of the first detection unit 112 and the other terminal of the power supply 40, and is supplied with the second potential. The first potential terminal 208 is connected to the first potential terminal 202 of the first detection unit 112 and one terminal of the power supply 40, and is supplied with the first potential.

The second terminal 260 outputs a negative detection signal V _A− and the fourth terminal 360 outputs a negative detection signal V _B− having a phase different from that of the detection signal V _A− . In the first detection unit 112, the first terminal 250 outputs a positive detection signal V _{A +} , and the third terminal 350 outputs a positive detection signal V _{B +} having a phase different from that of the detection signal V _{A +} . That is, the detection device 110 of the modified example outputs the first differential signal from the set of the first terminal 250 and the second terminal 260, and the first differential signal from the set of the third terminal 350 and the fourth terminal 360. A second differential signal having a different phase is output.

  Since the first detection unit 112 generates a positive signal and the second detection unit 114 generates a negative signal, the shape of the magnetoresistive element formed in the second detection unit 114 is formed in the first detection unit 112. It is desirable to form a shape substantially similar to the shape of the magnetoresistive element. In addition, the shape of the magnetoresistive element formed in the second detection unit 114 is more preferably substantially the same as the shape of the magnetoresistive element formed in the first detection unit 112.

  That is, the magnetic sensitive portions of the second bridge magnetoresistive element 220 and the fourth bridge magnetoresistive element 320 are arranged in the moving direction of the rotating body 10 and provided on the surface of the substrate 30 that should face the rotating body 10. The second bridge magnetoresistive element 220 includes a third magnetoresistive element 222 and a fourth magnetoresistive element 224, and the fourth bridge magnetoresistive element 320 includes a seventh magnetoresistive element 322 and an eighth magnetoresistive element 324. Have

  The third magnetoresistive element 222, the fourth magnetoresistive element 224, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324 each include two magnetosensitive parts. In addition, the respective magnetic sensing parts included in each resistance element are arranged at substantially equal intervals in the moving direction of the rotating body 10. In the third magnetoresistive element 222, the fourth magnetoresistive element 224, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324, the ranges in which the magnetosensitive portions are provided overlap in the width direction.

  Further, the third magnetoresistive element 222, the fourth magnetoresistive element 224, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324 are arranged on the substrate 30 at equal intervals, the first region 512, the second region 514, They are formed in the third region 516 and the fourth region 518, respectively. FIG. 7 shows the first magnetoresistive element 212 and the third magnetoresistive element 222 in the first region 512, the fifth magnetoresistive element 312 and the seventh magnetoresistive element 322 in the second region 514, and the third magnetoresistive element 322 in the third region 516. 2 shows an example in which a second magnetoresistive element 214 and a fourth magnetoresistive element 224 are formed, and a sixth magnetoresistive element 314 and an eighth magnetoresistive element 324 are formed in a fourth region 518, respectively.

  Thereby, for example, when the rotating body 10 is rotating, at the first time point, the first magnetoresistive element 212 and the third magnetoresistive element 222 face the tooth tip surface of the first tooth of the gear, and the next In the second time point, the fifth magnetoresistive element 312 and the seventh magnetoresistive element 322 can face the tooth tip surface of the first tooth of the gear. In this manner, the plurality of magnetoresistive elements can face the tooth tip surfaces of the gears for each region in the order in which they are arranged in the moving direction as time advances. Similarly, the plurality of magnetoresistive elements can be opposed to the recesses of the rotating body 10 for each region in the order in which they are arranged in the moving direction as time advances.

  The third magnetoresistive element 222 is connected between the second potential of the power supply 40 and the second terminal 260, and the fourth magnetoresistive element 224 is connected between the second terminal 260 and the first potential of the power supply 40. Is done. That is, the voltage applied to the second bridge magnetoresistive element 220 is substantially the same as the voltage applied to the first bridge magnetoresistive element 210, and the application direction is reversed. Similarly, the voltage applied to the fourth bridge magnetoresistive element 320 is substantially the same as the voltage applied to the third bridge magnetoresistive element 310, and the application direction is reversed. Thereby, the detection apparatus 110 can output the detection result which detected the movement of the rotary body 10 correctly as a differential detection signal.

FIG. 8 shows an example of an amplifier circuit 530 corresponding to the detection device 110 of the modification shown in FIG. In this case, the detection system 100 further includes an amplifier circuit 530 shown in FIG. FIG. 8 shows an example in which the amplifier circuit 530 converts the differential signal output by the set of the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 of the detection device 110 according to the modification to a single-ended output. That is, the amplifier circuit 530 is a two-input one-output amplifier circuit, and as an example, is an amplifier circuit including an operational amplifier and the like. In the amplifier circuit 530, the positive detection signal V _{A +} from the first terminal 250 is input to one input terminal, and the negative detection signal V _A− from the second terminal 260 is input to the other input terminal.

The amplification circuit 530 reduces common-mode noise and amplifies signal components that are 180 degrees out of phase with respect to the input positive detection signal V _{A +} and negative detection signal V _A− . Similarly, the detection device 110 further includes an amplifier circuit that makes a differential signal output from the set of the third bridge magnetoresistive element 310 and the fourth bridge magnetoresistive element 320 of the modified detection device 110 a single-ended output. It's okay. In other words, the detection device 110 has two amplifier circuits respectively corresponding to the two differential signals output from the detection device 110 according to the modified example, and can realize an increase in signal strength of the two detection signals and a reduction in common-mode noise. . The detection system 100 may further include a determination unit that determines the rotation operation of the rotating body 10 based on the two detection signals. The detection system 100 can detect the rotation operation of the rotating body 10 more accurately.

  FIG. 9 shows a configuration example of a detection system 100 including the detection device 110 of the modification shown in FIG. As described above, the detection system 100 can improve S / N by using two detection signals as differential signals. Here, as shown in FIG. 9, the detection device 110 according to the modification includes a first detection unit 112 that generates a positive detection signal and a second detection unit 114 that generates a negative detection signal. 10 are provided at different positions in the width direction of the substrate 30 perpendicular to the moving direction.

  Here, when a defect such as a crack, a chip, or a crack occurs in the first tooth 12 of the rotating body 10, the distance from the magnetic field generator 20 is not constant in the direction orthogonal to the moving direction of the tooth tip surface. Sometimes. For example, when the first tooth 12 has a defect 18 in part, the region having the defect 18 has a greater distance from the magnetic field generation unit 20 than the normal region of the tooth tip surface. As a result, a difference occurs between the magnetic flux density in the region having the defect 18 and the magnetic flux density in the normal region on the tooth tip surface of the first tooth 12. And when the said defect 18 generate | occur | produced in the 1st detection part 112 side of a tooth tip surface, the signal amplitude of the detection signal of the 1st detection part 112 is compared with the signal amplitude of the detection signal of the 2nd detection part 114 It may become smaller.

  In this case, the signal output from the amplifier circuit 530 cannot cancel the common-mode noise, and may cause distortion in the signal component. That is, in the detection system 100, when such a rotating body 10 has a defect, the S / N may be lowered. Accordingly, the detection system 100 according to the present embodiment improves the S / N reduction caused by the defect of the rotating body 10 by overlapping the magnetic sensitive portions of the bridge magnetoresistive elements of the detection device 110 in the width direction. Such a detection device 110 will be described next.

  FIG. 10 shows a first configuration example of the detection apparatus 110 according to this embodiment. The detection device 110 outputs a detection signal of a differential signal according to the rotation of the rotating body 10. FIG. 10 shows an example of outputting the first differential signal described in FIG. The detection device 110 includes a substrate 30, a first potential terminal 202, a second potential terminal 204, a second potential terminal 206, a first potential terminal 208, a first bridge magnetoresistive element 210, a second bridge magnetoresistive element 220, a first A terminal 250 and a second terminal 260 are provided. The substrate 30 is provided with a first bridge magnetoresistive element 210 and a second bridge magnetoresistive element 220 on a surface that should face the rotating body 10. The substrate 30 is a substrate formed of, for example, a semiconductor, glass, ceramic, or the like.

The first potential terminal 202 and the first potential terminal 208 are connected to one terminal of the power supply 40 and supplied with the first potential. The second potential terminal 204 and the second potential terminal 206 are connected to the other terminal of the power supply 40 and supplied with the second potential. The first terminal 250 outputs a positive detection signal V _{A +} , and the second terminal 260 outputs a negative detection signal V _A− . That is, the first terminal 250 functions as a first differential terminal, the second terminal 260 functions as a second differential terminal, and functions as a differential terminal pair that outputs a first differential signal.

  The first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 differentially detect a change in magnetic flux density accompanying the movement of the rotating body 10. The magnetic sensitive parts of the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 are arranged in the moving direction of the rotating body 10. Here, in FIG. 10, the direction indicated by the arrow is the moving direction of the rotating body 10. The first bridge magnetoresistive element 210 includes a first magnetoresistive element 212 and a second magnetoresistive element 214, and the second bridge magnetoresistive element 220 includes a third magnetoresistive element 222 and a fourth magnetoresistive element 224. Have The first magnetoresistive element 212 is connected between the first terminal 250 and the first potential, and the second magnetoresistive element 214 is connected between the first terminal 250 and the second potential. The third magnetoresistance element 222 is connected between the second terminal 260 and the second potential, and the fourth magnetoresistance element 224 is connected between the second terminal 260 and the first potential.

  The first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 are formed so that at least partly overlaps the range where the magnetosensitive part is provided in the width direction orthogonal to the moving direction of the rotating body 10. That is, in the first magnetoresistive element 212, the second magnetoresistive element 214, the third magnetoresistive element 222, and the fourth magnetoresistive element 224, at least a part of the range in which the magnetosensitive portion is provided overlaps in the width direction.

  Each of the first magnetoresistive element 212, the second magnetoresistive element 214, the third magnetoresistive element 222, and the fourth magnetoresistive element 224 has a plurality of sensitivity provided at different positions in the moving direction of the rotating body 10. Includes magnetic parts. FIG. 10 shows an example in which the first magnetoresistive element 212, the second magnetoresistive element 214, the third magnetoresistive element 222, and the fourth magnetoresistive element 224 each include two magnetosensitive parts.

  Here, each of the magnetic sensitive portions is shown in a substantially rectangular shape extending in the width direction. FIG. 10 shows an example in which the magnetic sensitive parts included in the first magnetoresistive element 212 and the third magnetoresistive element 222 are arranged at substantially equal intervals in the moving direction of the rotating body 10. Similarly, an example in which the magnetic sensitive parts included in the second magnetoresistive element 214 and the fourth magnetoresistive element 224 are arranged at substantially equal intervals in the moving direction of the rotating body 10 is shown.

  FIG. 10 shows an example in which each magnetic sensing unit is arranged at a position translated in the moving direction of the rotating body 10 as an example. In this case, in the first magnetoresistive element 212, the second magnetoresistive element 214, the third magnetoresistive element 222, and the fourth magnetoresistive element 224, the ranges in which the magnetosensitive portions are provided overlap in the width direction. .

  The first magnetoresistive element 212, the second magnetoresistive element 214, the third magnetoresistive element 222, and the fourth magnetoresistive element 224 are arranged on the substrate 30 at equal intervals, the first region 512, the second region 514, Of the three regions 516, the first region 512 and the third region 516 sandwiching the second region 514 are formed. The interval between the first region 512, the second region 514, and the third region 516 is approximately ¼ of the circular pitch of the gear teeth of the rotating body 10 and corresponds to the distance between the rotating body 10 and the detection device 110. It is approximately equal to the value multiplied by the coefficient. Thereby, each magnetoresistive element can oppose a corresponding tooth-tip surface in the corresponding time point during rotation of a gearwheel.

  FIG. 10 shows an example in which the first magnetoresistive element 212 and the third magnetoresistive element 222 are formed in the first region 512. Here, each of the magnetosensitive parts of the first magnetoresistive element 212 and the third magnetoresistive element 222 has the first magnetoresistive element 212 and the third magnetoresistive element in the moving direction of the rotating body 10. The element 222 is disposed between the magnetic sensing parts of the other magnetoresistive element. FIG. 10 shows an example in which the two magnetosensitive portions of the first magnetoresistive element 212 are arranged between the two magnetosensitive portions of the third magnetoresistive element 222 in the moving direction of the rotating body 10.

  Thereby, the average position in the 1st area | region 512 of the 1st magnetoresistive element 212 and the 3rd magnetoresistive element 222 can be made into the substantially center position of this 1st area | region 512 in the moving direction of the rotary body 10. FIG. . Therefore, in the process in which the rotating body 10 moves, for example, even if one magnetosensitive part of the first magnetoresistive element 212 has a different resistance value compared to the other magnetosensitive part, The two magnetic sensitive parts also generate the same tendency. Therefore, since signals having the same tendency can be output on the positive side and the negative side of the differential signal, it is possible to prevent distortion from occurring.

  FIG. 10 shows an example in which the second magnetoresistive element 214 and the fourth magnetoresistive element 224 are formed in the third region 516. As in the first region, the plurality of magnetosensitive parts of one of the second magnetoresistive element 214 and the fourth magnetoresistive element 224 are arranged in the moving direction of the rotating body 10 with the second magnetoresistive element 214 and The fourth magnetoresistive element 224 is disposed between the magnetosensitive parts of the other magnetoresistive element. Further, the arrangement of the magnetic sensing portions of the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 in the first region 512 and the first bridge magnetoresistive element 210 and the second bridge magnetoresistive in the third region 516 are also shown. It is desirable that the arrangement of the magnetic sensing portions of the element 220 is substantially the same.

  FIG. 10 shows an example in which the two magnetosensitive portions of the second magnetoresistive element 214 are arranged between the two magnetosensitive portions of the fourth magnetoresistive element 224 in the moving direction of the rotating body 10. As a result, even if a temporary unbalance occurs in the resistance value of the magnetosensitive part included in one bridge magnetoresistive element, the resistance value of the magnetosensitive part included in the other bridge magnetoresistive element also has the same unbalance. It is possible to generate a differential amplification signal that is generated and reduced in distortion.

  Further, for example, when the rotating body 10 is rotating, at the first time point, the first magnetoresistive element 212 and the third magnetoresistive element 222 are opposed to the tooth tip surface of the first tooth of the gear, and the next At a point in time, the second magnetoresistive element 214 and the fourth magnetoresistive element 224 can face the tooth tip surface of the first tooth of the gear. In this manner, the plurality of magnetoresistive elements can face the tooth tip surfaces of the gears for each region in the order in which they are arranged in the moving direction as time advances.

  Therefore, the detection device 110 can output a detection result obtained by accurately detecting the movement of the rotating body 10 as a differential detection signal. That is, the detection apparatus 110 according to the present embodiment can output a detection signal that is substantially the same as the first differential signal described in FIG. In addition, the detection device 110 according to the present embodiment is different from the detection device 110 of the modified example described in FIG. 7 in that the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 have the moving direction of the rotating body 10. At least a portion overlaps in the orthogonal width direction. Therefore, even if a part of the rotating body 10 has a defect or the like, a detection signal change corresponding to the defect occurs in the detection signals of both the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220. To do.

  In particular, as shown in the example of FIG. 10, when the overlap in the width direction of the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 is equal or larger, the change in the detection signal according to the defect occurs. Will almost match. The detection system 100 according to this embodiment includes the amplifier circuit 530 illustrated in FIG. 8, and may supply the differential signal output from the detection device 110 to the amplifier circuit 530.

  Based on the differential signal output from the detection device 110, the amplifier circuit 530 can cancel and reduce the common-mode noise, and can also reduce the distortion of the signal component. Therefore, the detection system 100 including the detection device 110 according to the present embodiment accurately detects the movement of the rotating body 10 and improves the S / N by the differential signal even when the rotating body 10 has a defect, The rotational speed and the rotational speed of the rotating body 10 can be detected.

  Although the detection apparatus 110 according to the present embodiment has been described with respect to the example in which the first differential signal is output, the present invention is not limited to this. The detection device 110 may output the first differential signal and the second differential signal, and the detection system 100 may detect the rotation direction of the rotating body 10. Next, the detection device 110 that outputs the first differential signal and the second differential signal will be described.

  FIG. 11 shows a modification of the detection device 110 according to the present embodiment. In the detection device 110 according to the modified example of FIG. 11, the same reference numerals are given to the substantially same operations as those of the detection device 110 according to the present embodiment shown in FIG. The detection device 110 according to the modified example includes a first bridge magnetoresistive element 210 and a second bridge magnetoresistive element 220 having substantially the same shape as the detection device 110 shown in FIG. The detection device 110 according to the modification further includes a third terminal 350, a fourth terminal 360, a third bridge magnetoresistive element 310, and a fourth bridge magnetoresistive element 320.

The third terminal 350 outputs a positive detection signal V _{B +} , and the fourth terminal 360 outputs a negative detection signal V _B− . That is, the third terminal 350 functions as a third differential terminal, the fourth terminal 360 functions as a fourth differential terminal, and functions as a differential terminal pair that outputs a second differential signal. The third bridge magnetoresistive element 310 and the fourth bridge magnetoresistive element 320 differentially detect a change in magnetic flux density accompanying the movement of the rotating body 10. The magnetic sensitive parts of the first bridge magnetoresistive element 210, the second bridge magnetoresistive element 220, the third bridge magnetoresistive element 310, and the fourth bridge magnetoresistive element 320 are arranged in the moving direction of the rotating body 10.

  The third bridge magnetoresistive element 310 has a fifth magnetoresistive element 312 and a sixth magnetoresistive element 314, and the fourth bridge magnetoresistive element 320 has a seventh magnetoresistive element 322 and an eighth magnetoresistive element 324. . The fifth magnetoresistive element 312 is connected between the third terminal 350 and the first potential, and the sixth magnetoresistive element 314 is connected between the third terminal 350 and the second potential. The seventh magnetoresistance element 322 is connected between the fourth terminal 360 and the second potential, and the eighth magnetoresistance element 324 is connected between the fourth terminal 360 and the first potential.

  The first bridge magnetoresistive element 210, the second bridge magnetoresistive element 220, the third bridge magnetoresistive element 310, and the fourth bridge magnetoresistive element 320 overlap at least partially in the width direction in which the magnetosensitive part is provided. Formed as follows. In other words, the fifth magnetoresistive element 312, the sixth magnetoresistive element 314, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324 have at least partly overlapping ranges in which the magnetic sensitive portions are provided in the width direction. In addition, it is desirable that the eight magnetoresistive elements from the first magnetoresistive element 212 to the eighth magnetoresistive element 324 have at least partly overlapping ranges in which the magnetosensitive portions are provided in the width direction.

  Note that each of the fifth magnetoresistive element 312, the sixth magnetoresistive element 314, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324 has a plurality of senses provided at different positions in the moving direction of the rotating body 10. Includes magnetic parts. FIG. 11 shows an example in which the fifth magnetoresistive element 312, the sixth magnetoresistive element 314, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324 each include two magnetosensitive portions.

  Here, each of the magnetic sensitive portions is shown in a substantially rectangular shape extending in the width direction. FIG. 11 shows an example in which the magnetic sensitive parts included in the eight magnetoresistive elements from the first magnetoresistive element 212 to the eighth magnetoresistive element 324 are arranged at substantially equal intervals in the moving direction of the rotating body 10. FIG. 11 shows an example in which each magnetic sensing unit is arranged at a position translated in the moving direction of the rotating body 10 as an example. In this case, in the eight magnetoresistive elements from the first magnetoresistive element 212 to the eighth magnetoresistive element 324, the ranges in which the magnetic sensitive portions are provided all overlap in the width direction.

  In the moving direction of the rotating body 10, the fifth magnetoresistive element 312 and the seventh magnetoresistive element 322, or the sixth magnetoresistive element 314 and the eighth magnetism between the first magnetoresistive element 212 and the second magnetoresistive element 214. A resistance element 324 is disposed. That is, the fifth magnetoresistive element 312 and the seventh magnetoresistive element 322 or the sixth magnetoresistive element 314 and the eighth magnetoresistive element 324 are formed in the second region 514.

  FIG. 11 shows the first magnetoresistive element 212 and the third magnetoresistive element 222 in the first region 512, the fifth magnetoresistive element 312 and the seventh magnetoresistive element 322 in the second region 514, and the third magnetoresistive element 322 in the third region 516. 2 shows an example in which a second magnetoresistive element 214 and a fourth magnetoresistive element 224 are formed, and a sixth magnetoresistive element 314 and an eighth magnetoresistive element 324 are formed in a fourth region 518, respectively. Thereby, for example, when the rotating body 10 is rotating, at the first time point, the first magnetoresistive element 212 and the third magnetoresistive element 222 face the tooth tip surface of the first tooth of the gear, and the next At this point, the fifth magnetoresistive element 312 and the seventh magnetoresistive element 322 can face the tooth tip surface of the first tooth of the gear. In this manner, the plurality of magnetoresistive elements can face the tooth tip surfaces of the gears for each region in the order in which they are arranged in the moving direction as time advances.

  In addition, each of the magnetosensitive elements of one of the fifth magnetoresistive element 312 and the seventh magnetoresistive element 322 has the fifth magnetoresistive element 312 and the seventh magnetoresistive element in the moving direction of the rotating body 10. The other magnetoresistive element 322 is disposed between the magnetic sensitive parts. Similarly, each of the magnetosensitive elements of one of the sixth magnetoresistive element 314 and the eighth magnetoresistive element 324 has the sixth magnetoresistive element 314 and the eighth magnetoresistive element in the moving direction of the rotating body 10. The element 324 is disposed between the magnetosensitive parts of the other magnetoresistive element.

  By the above, the 3rd bridge magnetoresistive element 310 and the 4th bridge magnetoresistive element 320 can output the detection result which detected the movement of the rotary body 10 correctly as a differential detection signal. In addition, the third bridge magnetoresistive element 310 and the fourth bridge magnetoresistive element 320 are second differential signals whose phases are different from the differential signals output from the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220. Can be output. In the example of FIG. 11, the four regions from the first region 512 to the fourth region 518 are arranged at ¼ intervals of the circle pitch p of the teeth, so the phase difference between the first differential signal and the second differential signal is , Approximately 90 degrees.

  In addition, the detection device 110 according to the present modification has four magnetosensitive portions from the first bridge magnetoresistive element 210 to the fourth bridge magnetoresistive element 320 in the same manner as the detection device 110 according to the present embodiment described with reference to FIG. At least partially overlap in the width direction orthogonal to the moving direction of the rotating body 10. Therefore, even if a part of the rotator 10 has a defect or the like, a change in the detection signal corresponding to the defect occurs in the detection signals of the four magnetic sensitive portions.

  The detection system 100 according to the present embodiment includes the two amplification circuits 530 illustrated in FIG. 8, and the first and second differential signals output from the detection device 110 are used as the two amplification circuits 530. May be supplied respectively. The two amplifier circuits 530 can each output two detection signals with reduced in-phase noise and reduced distortion of signal components based on the two differential signals output from the detection device 110. Therefore, the detection system 100 including the detection device 110 according to the present modification accurately detects the movement of the rotating body 10 and improves the S / N by the differential signal even when the rotating body 10 has a defect, The rotational motion of the rotating body 10 can be detected.

  In the detection apparatus 110 according to the present embodiment described above, the example in which the magnetic sensitive parts included in the first magnetoresistive element 212 and the third magnetoresistive element 222 are arranged at equal intervals in the first region 512 has been described. It is not limited to this. The first magnetoresistive element 212 and the third magnetoresistive element 222 are formed in the first region, and the absolute value of the amplitude intensity of the detection signal only needs to be approximately the same according to the rotation of the rotating body 10.

  Even when the magnetic sensitive parts included in the first magnetoresistive element 212 and the third magnetoresistive element 222 are arranged at unequal intervals, it is desirable that the average positions in the moving direction of the rotating body 10 substantially coincide. For example, the difference in the movement direction of the rotating body 10 between the average position of the plurality of magnetic sensing parts in the first magnetoresistance element 212 and the average position of the plurality of magnetic sensing parts in the third magnetoresistance element 222 is adjacent in the movement direction. It is desirable that the distance is less than the distance between the magnetic sensing parts. Here, the distance between adjacent magnetic sensing parts is preferably the minimum value among the distances between the plurality of magnetic sensing parts. Instead of this, the average value or the maximum value may be used. Good.

  Similarly, even when the magnetic sensitive parts included in the second magnetoresistive element 214 and the fourth magnetoresistive element 224 are arranged at unequal intervals in the third region 516, the average positions in the moving direction of the rotating body 10 are substantially the same. It is desirable. For example, the difference in the moving direction of the rotating body 10 between the average position of the plurality of magnetosensitive parts in the second magnetoresistive element 214 and the average position of the plurality of magnetosensitive parts in the fourth magnetoresistive element 224 is adjacent in the moving direction. It is desirable that the distance is less than the distance between the magnetic sensing parts. Similarly, the fifth magnetoresistive element 312, the sixth magnetoresistive element 314, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324 formed in the second region 514 and the fourth region 518 are also unequal. It may be arranged at intervals, and it is desirable that the average positions in each region are substantially the same.

  As described above, it has been described that the detection device 110 according to the present embodiment and the detection system 100 including the detection device 110 can accurately detect the rotation operation of the rotating body 10. In the above description, it is desirable that the magnetic field generated by the magnetic field generator 20 has a substantially constant magnetic flux density in a region including the magnetic sensitive part of the detection device 110. However, the magnetic field generator 20 may generate a magnetic field in which the magnetic flux density gradually increases or decreases in the moving direction of the rotating body 10. Next, the detection system 100 including such a magnetic field generator 20 will be described.

  FIG. 12 shows an example in which the magnetic field generator 20 according to the present embodiment generates a magnetic field having a magnetic flux density distribution. For the sake of convenience, FIG. 12 omits the description of the bridge magnetoresistive elements other than the first bridge magnetoresistive element 210 of the detection device 110. Further, in FIG. 12, the order in which the first magnetoresistive element 212 and the second magnetoresistive element 214 are arranged, the voltage application direction of the power supply 40, and the moving direction of the rotating body 10 are different from those in FIG. An example is shown.

  FIG. 12 shows a magnetic field in which the magnetic field generating unit 20 is a disk-shaped permanent magnet, and the magnetic flux density generated from the central portion of the circular surface facing the rotating body 10 is the largest, and the magnetic flux density decreases as it approaches the outer periphery. An example of generating When the size of the magnetic field generation unit 20 is approximately the same size as the region including the first magnetoresistive element 212 and the second magnetoresistive element 214 of the detection device 110, the first magnetoresistive element 212 and the second magnetoresistive element 212 The magnetic flux density detected by the magnetoresistive element 214 has a distribution.

  Here, when the rotating body 10 rotates, for example, the magnitude of the magnetic flux changes in accordance with the rotation of one tooth tip surface. Then, an eddy current is generated by electromagnetic induction on the tooth tip surface, and a magnetic flux is generated in a direction that cancels the change of the magnetic flux (Lenz's law). Here, the induced electromotive force V = −dφ / dt (φ = BS), and the current I is I = V / R. Here, φ is the magnetic flux, dφ / dt is the amount of change in magnetic flux per unit time, S is the surface where current is generated, B is the magnetic flux density, and R is the resistance value of the conductor where eddy current is generated.

  That is, when the tooth tip of the gear moves so as to approach the center of the magnetic field generating unit 20, the magnetic flux on the tooth tip surface changes in the increasing direction. Produces a magnetic flux in the opposite direction. For example, in FIG. 12, when the rotating body 10 moves in the direction of the leftward arrow in the figure and the first tooth 12 moves to a position facing the second magnetoresistive element 214, the teeth of the first tooth 12 The magnetic flux applied to the front surface changes in a direction that increases as the rotating body 10 moves. As a result, the first tooth 12 generates a magnetic flux from the first tooth 12 toward the magnetic field generator 20. Therefore, the second magnetoresistive element 214 detects a magnetic flux that is smaller than the magnetic flux of the tip surface of the first tooth 12 when the gear is stationary.

  In addition, when the tooth tip of the gear moves away from the center of the magnetic field generation unit 20, the magnetic flux on the tooth tip surface changes in a decreasing direction. Magnetic flux in the same direction is generated. For example, in FIG. 12, when the rotating body 10 moves in the direction of the leftward arrow in the figure and the first tooth 12 moves to a position facing the first magnetoresistive element 212, it is applied to the first tooth 12. The magnetic flux to be changed changes in a direction to decrease as the rotating body 10 moves. Thereby, the first tooth 12 generates a magnetic flux from the magnetic field generator 20 toward the first tooth 12. Therefore, the first magnetoresistive element 212 detects a magnetic flux larger than the magnetic flux of the tooth tip surface of the first tooth 12 when the gear is stationary.

  The magnetic flux detected by the first magnetoresistive element 212 and the second magnetoresistive element 214 has been described based on the magnetic flux on the tooth tip surface of the first tooth 12, but is not limited to this, and the rotating body The same can be said for the entire ten. That is, in the detection system having the configuration shown in FIG. 12, the magnetic flux detected by the second magnetoresistive element 214 is smaller than the magnetic flux from the magnetic field generator 20 in response to the movement of the rotating body 10 in the direction of the arrow. The magnetic flux detected by the magnetoresistive element 212 is larger than the magnetic flux from the magnetic field generator 20.

  As a result, the offset voltage is superimposed on the detection result of the magnetic flux output from the first terminal 250. Such an offset voltage changes according to the degree of the magnetic field gradient of the magnetic field generator 20, the rotational speed of the rotating body 10, and the direction of rotation. An example of such a change in offset voltage is shown in FIG.

  FIG. 13 shows an example of the offset voltage superimposed on the detection result of the detection apparatus 110 according to this embodiment. The horizontal axis in FIG. 13 is the rotational speed of the rotating body 10, and the vertical axis is the offset voltage change. As shown in FIG. 13, as the rotational speed of the rotating body 10 increases, the amount of change in magnetic flux increases, so that the change in offset voltage also tends to increase.

  Further, when the rotation direction is reversed, the increase and decrease of the magnetic flux is also reversed. For example, when the rotating body 10 moves to the right in FIG. 12, the magnetic flux detected by the first magnetoresistive element 212 is smaller than the magnetic flux generated by the magnetic field generator 20, and the magnetic flux detected by the second magnetoresistive element 214. Becomes larger than the magnetic flux generated by the magnetic field generator 20. In FIG. 13, the rotation in one direction of the rotating body 10 is CW, and the rotation in the opposite direction to CW is CCW. In this way, the offset voltage switches between positive and negative signs according to the rotation direction. Such an offset voltage is superimposed on the detection signal output from the detection device 110.

FIG. 14 shows an example in which an offset voltage is superimposed on a detection signal output from the detection device 110. The horizontal axis in FIG. 14 indicates time t, and the vertical axis indicates the voltage value V of the detection signal. FIG. 14 shows an example of a result of detecting the rotation operation of the rotating body 10 using, for example, the detection device 110 that outputs a differential signal as described in FIG. 10 and a magnetic flux having a magnetic flux density distribution. Here, the positive signal of the differential signal output from the first terminal 250 of the detection device 110 is denoted as V _{A +} ', and the negative signal of the differential signal output from the second terminal 260 is denoted as V _A- '.

Here, the resistance value of the first magnetoresistance element 212 and the third magnetoresistive elements 222 and _{R 1,} the rotary body 10 when the resistance value of the second magnetoresistance element 214 and the fourth magnetoresistive element 224 and as _{R 2} The positive side signal V _{A +} and the positive side signal V _A− at the time when is stationary are calculated as follows.
(Equation 1)
V _{A +} = (V _dd −V _ss ) · R ₂ / (R ₁ + R ₂ )
V _A− = (V _dd −V _ss ) · R ₁ / (R ₁ + R ₂ )

The positive side signal V _{A +} 'is a signal obtained by adding the offset voltage V _OFF to the positive side signal V _{A +} when the offset is not superimposed. Similarly, the negative side signal V _A− ′ is a signal obtained by subtracting the offset voltage V _OFF from the negative side signal V _A− where no offset is superimposed. That is, the positive side signal V _{A +} 'and the negative side signal V _A- ' are expressed by the following equations.
(Equation 2)
V _{A +} '= V _{A +} + V _OFF
V _A- '= V _A- -V _OFF

By rotating body 10 is rotated, the resistance value R ₁ of the first magnetoresistive element 212 and the third magnetoresistive element 222 due to the eddy current is reduced, the second magnetoresistive element 214 and the fourth magnetic R ₂ increases the resistance value of the resistance element 224. Here, assuming that the decrease amount of the resistance value R ₁ is ΔR ₁ and the increase amount of the resistance value R ₂ is ΔR ₂ , the positive side signal V _{A +} ′ and the negative side signal V _A− ′ are expressed by the following equations.
(Equation 3)
V _{A +} '= (V _dd −V _ss ) · (R ₂ + ΔR ₂ ) / (R ₁ −ΔR ₁ + R ₂ + ΔR ₂ )
V _A− ′ = (V _dd −V _ss ) · (R ₁ −ΔR ₁ ) / (R ₁ −ΔR ₁ + R ₂ + ΔR ₂ )

Here, in FIG. 12, since the absolute values of the gradients of the magnetic flux changes of the magnetic fields input to the first magnetoresistive element 212 and the second magnetoresistive element 214 are substantially equal, ΔR = ΔR ₁ ≈ΔR ₂ and 3) The equation is shown as (Equation 4).
(Equation 4)
V _{A +} '= V _{A +} + (V _dd −V _ss ) · ΔR / (R ₁ + R ₂ ) = V _{A +} + V _OFF
V _A− '= V _A− − (V _dd −V _ss ) · ΔR / (R ₁ + R ₂ ) = V _A− −V _OFF

Therefore, if the common-mode noise is removed based on the positive side signal V _{A +} ′ and the negative side signal V _A− ′, the offset voltage generated by the eddy current is doubled and remains.
(Equation 5)
V _{A +} '-V _A- ' = V _{A +} -V _A- + 2V _OFF

  As described above, when the magnetic field generator 20 has a distribution of magnetic flux density, a magnetic flux due to eddy current is generated according to the distribution and the rotation speed, which may cause an error in the detection result of the detection device 110. Accordingly, the detection device 110 that reduces errors caused by the magnetic flux density distribution of the magnetic field generator 20 will be described next.

  FIG. 15 shows a detection system 100 including a second configuration example of the detection apparatus 110 according to the present embodiment. The detection system 100 includes a rotating body 10, a magnetic field generation unit 20, a power supply 40, and a detection device 110 of the second configuration example. Since the rotary body 10 and the power supply 40 have already been described with reference to FIGS.

  The magnetic field generator 20 has a magnetic flux density distributed in the moving direction of the rotating body 10 and applies the magnetic flux density to the first magnetoresistive element 212 and the second magnetoresistive element 214. The magnetic field generation unit 20 functions as a magnetic flux density application unit having a distribution. The magnetic field generation unit 20 includes a plate-shaped magnet that should be disposed to face the rotating body 10 with the first magnetoresistive element 212 and the second magnetoresistive element 214 interposed therebetween. FIG. 15 shows an example in which the magnetic field generator 20 generates a magnetic field in which the magnetic flux density gradually decreases from the center of the flat plate toward the end.

  The detection device 110 of the second configuration example shows an example including a first bridge magnetoresistive element 210 having a first magnetoresistive element 212 and a second magnetoresistive element 214, and a first terminal 250. The first magnetoresistive element 212 is connected between the first terminal 250 and the first potential. Here, the detection signal output from the first terminal 250 is defined as a first detection signal.

  The second magnetoresistive element 214 is connected between the first terminal 250 and the second potential. The second magnetoresistive element 214 is disposed at a position shifted from the first magnetoresistive element 212 in the moving direction of the rotating body 10 or in the direction opposite to the moving direction. FIG. 15 shows an example in which the first magnetoresistive element 212 and the second magnetoresistive element 214 are arranged in this order in the moving direction of the rotating body 10 indicated by an arrow.

  The first magnetoresistive element 212 and the second magnetoresistive element 214 are arranged so that a magnetic field in which the magnetic flux density gradually increases or decreases in the moving direction is input. For example, the first magnetoresistive element 212 and the second magnetoresistive element 214 are arranged so as to be shifted in the moving direction of the rotating body 10 from the center of the plate-like magnet of the magnetic field generating unit 20 in the moving direction or in the direction opposite to the moving direction. The FIG. 15 shows an example in which the first magnetoresistive element 212 and the second magnetoresistive element 214 are shifted from the center of the magnetic field generation unit 20 to the opposite side in the moving direction in the moving direction of the rotating body 10 indicated by an arrow. Indicates.

  With such an arrangement, the magnetic fluxes respectively input from the magnetic field generator 20 to the first magnetoresistive element 212 and the second magnetoresistive element 214 have the same gradient of change in the magnetic flux with respect to the moving direction of the rotating body 10. For example, due to the arrangement of the first magnetoresistive element 212 and the second magnetoresistive element 214 shown in FIG. 15, the magnetic fields input from the magnetic field generator 20 to the first magnetoresistive element 212 and the second magnetoresistive element 214 are each a rotating body. The magnetic flux increases with respect to 10 moving directions.

Therefore, an eddy current is generated on the tooth tip surface of the gear as the rotating body 10 rotates, and the region where the first magnetoresistive element 212 and the second magnetoresistive element 214 are located is the magnetic flux applied by the magnetic field generator 20. Magnetic flux in the direction opposite to the direction is generated. That is, since the resistance values of the first magnetoresistive element 212 and the second magnetoresistive element 214 change in a decreasing direction, the first detection signal output from the first terminal 250 can be calculated as follows.
(Equation 6)
V _{A +} '= (V _dd −V _ss ) · (R ₂ −ΔR ₂ ) / (R ₁ + R ₂ −ΔR ₁ −ΔR ₂ )

Here, when the gradients of the magnetic flux changes of the input magnetic fields are substantially equal (ΔR = ΔR ₁ ≈ΔR ₂ ), the equation (6) is expressed as the following equation.
(Equation 7)
V _{A +} ′ = V _{A +} · (R ₁ + R ₂ −ΔR−ΔR · R ₁ / R ₂ ) / (R ₁ + R ₂ −2ΔR)

When the resistances of the first magnetoresistive element 212 and the second magnetoresistive element 214 are substantially equal (R ₁ ≈R ₂ ), (R ₁ + R ₂ −ΔR−ΔR · R ₁ / R ₂ ) = 1 (equation 8) The offset voltage of the first detection signal output from the first terminal 250 is substantially zero. Therefore, the first magnetoresistive element 212 and the second magnetoresistive element 214 are preferably formed of substantially the same material, and are disposed in a region where the distribution of the magnetic field generated by the magnetic field generator 20 changes linearly. It is desirable that Next, the first magnetoresistive element 212 and the second magnetoresistive element 214 will be described.
(Equation 8)
V _{A +} '= V _{A +}

FIG. 16 shows an example of the relationship between the magnetic flux input to the first magnetoresistive element 212 and the second magnetoresistive element 214 and the resistance value according to this embodiment. FIG. 16 shows the input magnetic flux when the first magnetoresistive element 212 and the second magnetoresistive element 214 are arranged shifted from the center of the magnetic field generating unit 20 in the direction opposite to the moving direction as shown in FIG. The relationship with the resistance value is shown. The horizontal axis in FIG. 16 indicates the magnetic flux input to the magnetoresistive element, and the vertical axis indicates the resistance value of the magnetoresistive element. Figure 16 is a variation of the resistance value of the first magnetoresistance element 212 and _{R 1,} the change in the resistance of the second magnetoresistive element 214 was set to _{R 2.}

The magnetic field generation unit 20 has a magnet gradient that generates a magnetic field in which the magnetic flux density decreases from the center of the flat plate toward the end. Therefore, at one point, the magnetic flux B ₁ input to the first magnetoresistive element 212 and the magnetic flux B ₂ input to the second magnetoresistive element 214 are different magnetic fluxes. In the case of the example shown in FIG. 15, the second magnetoresistive element 214 is disposed closer to the center of the magnetic field generating unit 20 than the first magnetoresistive element 212, so that the first magnetoresistive element 214 at the one time point flux B ₂ to be input to the resistive element 212 is larger than the magnetic flux B ₁ is input to the first magneto resistive element 212 at the time of the one.

  Here, it is desirable that the first magnetoresistive element 212 and the second magnetoresistive element 214 are formed so that the magnitudes of the resistance values corresponding to the magnetic fluxes input at one time point substantially coincide. For example, as shown in FIG. 16, the first magnetoresistive element 212 has a resistance value R corresponding to the magnetic flux B1 input at one time point, and the second magnetoresistive element 214 is input at the one time point. Each of the resistance values corresponding to the magnetic flux B2 is R.

  For example, the first magnetoresistive element 212 and the second magnetoresistive element 214 are formed of substantially the same material, and are formed in different shapes corresponding to the magnet gradient of the magnetic field generator 20. As a result, the first magnetoresistive element 212 and the second magnetoresistive element 214 have substantially the same slope of change in resistance value with respect to the change in input magnetic flux, and substantially the same resistance value with respect to the input of different magnetic fluxes. May be formed.

  In the detection apparatus 110 of the second configuration example described above, the first bridge magnetoresistive element 210 is arranged in a region where the signs of the gradients of the magnetic flux changes are the same, thereby reducing the offset voltage superimposed on the first detection signal. Explained. In addition, the detection device 110 may output the second detection signal by arranging the second bridge magnetoresistive element 220 in the same manner, and output a differential signal with a reduced offset voltage. The detection device 110 that outputs such a differential signal will be described next.

  FIG. 17 shows a detection system 100 including a third configuration example of the detection apparatus 110 according to the present embodiment. The detection system 100 includes a rotating body 10, a magnetic field generation unit 20, a power source 40, and a detection device 110 of a third configuration example. Since the rotating body 10, the magnetic field generation unit 20, and the power source 40 have already been described with reference to FIGS. 1, 2, and 15, etc., description thereof will be omitted here.

  The detection device 110 of the third configuration example includes a first bridge magnetoresistive element 210 and a second bridge magnetoresistive element 220. The first bridge magnetoresistive element 210 may have the same configuration and arrangement as the first bridge magnetoresistive element 210 described in the detection device 110 of the second configuration example, and description thereof is omitted here. That is, the first bridge magnetoresistive element 210 is arranged in a region where the signs of the magnetic flux inclinations are the same, and outputs a first detection signal with a reduced offset voltage from the first terminal.

  The second terminal 260 outputs a second detection signal that forms a differential pair with the first detection signal. The second bridge magnetoresistive element 220 includes a third magnetoresistive element 222, a fourth magnetoresistive element 224, and a second terminal 260. The third magnetoresistive element 222 is connected between the second terminal 260 and the second potential.

  The fourth magnetoresistive element 224 is connected between the second terminal 260 and the first potential. The fourth magnetoresistive element 224 is disposed at a position shifted from the third magnetoresistive element 222 in the moving direction of the rotating body 10 or in the direction opposite to the moving direction. FIG. 17 shows an example in which the fourth magnetoresistive element 224 and the third magnetoresistive element 222 are arranged in this order in the moving direction of the rotating body 10 indicated by an arrow.

  That is, the first magnetoresistive element 212, the second magnetoresistive element 214, the third magnetoresistive element 222, and the fourth magnetoresistive element 224 have the first magnetoresistive element 212, the second magnetoresistive element 224, The second magnetoresistive element 214, the fourth magnetoresistive element 224, and the third magnetoresistive element 222 are arranged in this order. FIG. 17 shows an example in which the first magnetoresistive element 212, the second magnetoresistive element 214, the fourth magnetoresistive element 224, and the third magnetoresistive element 222 are arranged in this order in the moving direction of the rotating body 10.

  In addition, the set of the first magnetoresistive element 212 and the second magnetoresistive element 214 and the set of the third magnetoresistive element 222 and the fourth magnetoresistive element 224 are in the moving direction or in the direction opposite to the moving direction. Are arranged at positions separated from one period of change in magnetic flux density. FIG. 17 shows an example in which the fourth magnetoresistive element 224 faces the second tooth 14 of the rotating body 10 when the second magnetoresistive element 214 faces the first tooth 12 of the rotating body 10. In this manner, the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 may respectively face different teeth of the gear.

  In addition, the set of the first magnetoresistive element 212 and the second magnetoresistive element 214 and the set of the third magnetoresistive element 222 and the fourth magnetoresistive element 224 have one cycle in the moving direction or in the direction opposite to the moving direction. It is arranged at a position exceeding the distance of less than 1.5 periods. That is, it is desirable that the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 are different from each other in gears and face each other adjacent teeth.

  The third magnetoresistive element 222 and the fourth magnetoresistive element 224 are arranged so that a magnetic field whose magnetic flux density gradually increases or decreases in the moving direction is input. For example, the third magnetoresistive element 222 and the fourth magnetoresistive element 224 are arranged so as to be shifted in the moving direction of the rotating body 10 from the center of the flat magnet of the magnetic field generating unit 20 in the moving direction or in the direction opposite to the moving direction. The The direction in which the third magnetoresistive element 222 and the fourth magnetoresistive element 224 are displaced is preferably opposite to the direction in which the first magnetoresistive element 212 and the second magnetoresistive element 214 are displaced.

  FIG. 17 shows an example in which the third magnetoresistive element 222 and the fourth magnetoresistive element 224 are shifted from the center of the magnetic field generation unit 20 toward the moving direction in the moving direction of the rotating body 10 indicated by an arrow. In this case, the magnetic field generator 20 changes the magnetic flux in the moving direction between the first magnetoresistive element 212 and the second magnetoresistive element 214 and the third magnetoresistive element 222 and the fourth magnetoresistive element 224. A magnetic flux having a reverse direction is applied.

For example, due to the arrangement of the detection device 110 shown in FIG. 17, the magnetic fluxes input from the magnetic field generation unit 20 to the first magnetoresistive element 212 and the second magnetoresistive element 214 are similar to those in the example of FIG. 15. The magnetic flux increases with respect to the moving direction. That is, the gradients of the magnetic flux changes input to the first magnetoresistive element 212 and the second magnetoresistive element 214 are substantially equal (ΔR ₁ ≈ΔR ₂ ), and the resistances of the first magnetoresistive element 212 and the second magnetoresistive element 214 are When they are substantially equal (R ₁ ≈R ₂ ), the offset voltage of the first detection signal output from the first terminal 250 is substantially zero.

Further, the magnetic fluxes respectively input from the magnetic field generator 20 to the third magnetoresistive element 222 and the fourth magnetoresistive element 224 are reduced in the moving direction of the rotating body 10. Therefore, the resistance values of the third magnetoresistive element 222 and the fourth magnetoresistive element 224 increase, respectively, contrary to the decrease of the resistance values of the first magnetoresistive element 212 and the second magnetoresistive element 214. Thereby, the second detection signal output from the second terminal 260 can be calculated as follows. Here, the resistance value of the third magnetoresistive element 222 and _{R 3,} the resistance value of the fourth magnetoresistive element 224 was set to _{R 4.}
(Equation 9)
V _A− ′ = (V _dd −V _ss ) · (R ₃ + ΔR ₃ ) / (R ₃ + R ₄ + ΔR ₃ + ΔR ₄ )

Here, when the gradients of the magnetic flux changes of the input magnetic fields are substantially equal (ΔR = ΔR ₃ ≈ΔR ₄ ), the equation (9) is expressed as the following equation.
(Equation 10)
V _A− ′ = V _A− ″ · (R ₃ + R ₄ + ΔR + ΔR · R ₄ / R ₃ ) / (R ₃ + R ₄ + 2ΔR)
V _A− ″ = (V _dd −V _ss ) · R ₄ / (R ₃ + R ₄ )

When the resistances of the third magnetoresistive element 222 and the fourth magnetoresistive element 224 are substantially equal (R ₃ ≈R ₄ ), (R ₃ + R ₄ −ΔR−ΔR · R ₃ / R ₄ ) / (R ₃ + R ₄ + 2ΔR) ) = 1 and 10), and the offset voltage of the second detection signal output from the second terminal 260 is substantially zero. Further, by making the resistance values of the third magnetoresistive element 222 and the fourth magnetoresistive element 224 substantially equal to the resistance values of the first magnetoresistive element 212 and the second magnetoresistive element 214, respectively (R ₃ ≈R ₁ , R ₄ ≈R ₂ ), the following equation holds:
(Equation 11)
V _A- '= V _A- ''
(Equation 12)
V _A− ′ = (V _dd −V _ss ) · R ₁ / (R ₁ + R ₂ ) = V _A−

  Therefore, the offset voltage of the differential signal can be made substantially zero. Accordingly, it is desirable that the four resistance elements from the first magnetoresistive element 212 to the fourth magnetoresistive element 224 are formed of substantially the same material. In addition, it is desirable that the third magnetoresistive element 222 and the fourth magnetoresistive element 224 are arranged in a region where the distribution of the magnetic field generated by the magnetic field generator 20 changes linearly. The third magnetoresistive element 222 and the fourth magnetoresistive element 224 may be formed like the first magnetoresistive element 212 and the second magnetoresistive element 214 described with reference to FIG.

  For example, as shown in FIG. 17, the distribution of the magnetic field generated by the magnetic field generator 20 may have a plane-symmetric distribution in the movement direction with respect to a plane perpendicular to the movement direction of the rotating body 10. In this case, it is desirable that the third magnetoresistive element 222 and the fourth magnetoresistive element 224 are disposed substantially plane-symmetrically with respect to the first magnetoresistive element 212 and the second magnetoresistive element 214 with respect to the perpendicular plane. . As a result, the offset voltage generated in each of the first detection signal and the second detection signal can be made comparable to the anti-phase noise. Next, the layout on the substrate 30 of the detection apparatus 110 of the third configuration example will be described.

  FIG. 18 shows a third configuration example of the detection apparatus 110 according to this embodiment. FIG. 18 shows an example in which the detection device 110 described in FIG. 17 is formed on the substrate 30. Therefore, the same reference numerals are given to substantially the same operations as those of the detection device 110 shown in FIG. Omitted. The substrate 30 has a first potential terminal 202, a second potential terminal 204, and a first bridge magnetoresistive element 210 (that is, the first magnetoresistive element 212 and the second magnetoresistive element 214) on the surface that should face the rotating body 10. The second bridge magnetoresistive element 220 (that is, the third magnetoresistive element 222 and the fourth magnetoresistive element 224), the first terminal 250, and the second terminal 260 are provided. The substrate 30 is a substrate formed of, for example, a semiconductor, glass, ceramic, or the like.

  The first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 differentially detect a change in magnetic flux density accompanying the movement of the rotating body 10. The magnetic sensitive parts of the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 are arranged in the moving direction of the rotating body 10. Here, in FIG. 18, the direction indicated by the arrow is the moving direction of the rotating body 10.

  The first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 are formed so that at least partly overlaps the range where the magnetosensitive part is provided in the width direction orthogonal to the moving direction of the rotating body 10. That is, in the first magnetoresistive element 212, the second magnetoresistive element 214, the third magnetoresistive element 222, and the fourth magnetoresistive element 224, at least a part of the range in which the magnetosensitive portion is provided overlaps in the width direction. FIG. 18 shows an example in which the four magnetoresistive elements from the first magnetoresistive element 212 to the fourth magnetoresistive element 224 overlap all the ranges in which the magnetosensitive portions are provided in the width direction.

  FIG. 18 shows an example in which the magnetic sensitive parts included in the first magnetoresistive element 212 and the second magnetoresistive element 214 are arranged at substantially equal intervals in the moving direction of the rotating body 10. Further, an example in which the first magnetoresistive element 212 is formed in the first region 612 and the second magnetoresistive element 214 is formed in the second region 614 is shown. Similarly, an example is shown in which the magnetic sensitive parts included in the third magnetoresistive element 222 and the fourth magnetoresistive element 224 are arranged at substantially equal intervals in the moving direction of the rotating body 10. The third magnetoresistive element 222 is formed in the third region 616, and the fourth magnetoresistive element 224 is formed in the fourth region 618.

  The four regions from the first region 612 to the fourth region 618 may be regions with substantially equal intervals corresponding to the circular pitch of the gear of the rotating body 10. In addition, the second region 614 and the third region 616 are formed at a predetermined interval. The four magnetoresistive elements from the first magnetoresistive element 212 to the fourth magnetoresistive element 224 may include a plurality of magnetosensitive portions in each region. FIG. 18 shows an example in which each of the four magnetoresistive elements includes two magnetosensitive parts. In each of the four magnetoresistive elements, it is desirable that the average position of the plurality of magnetically sensitive portions in each region in the moving direction of the rotator 10 is a substantially central position in each region.

  The detection system 100 including the detection device 110 of the third configuration example described above supplies the differential signals output from the first terminal 250 and the second terminal 260 to the amplification circuit 530 described with reference to FIG. In-phase noise can be reduced. In addition, as described with reference to FIG. 17, the detection system 100 can reduce the differential signal in the same manner as in-phase noise even if an offset voltage is generated in the differential signal. Therefore, the detection system 100 including the detection device 110 of the third configuration example can accurately detect the movement of the rotating body 10 and detect the rotation speed and the number of rotations of the rotating body 10.

  Although the detection apparatus 110 of the above 3rd structural example demonstrated the example which outputs the 1st differential signal which reduced the offset voltage, it is not limited to this. The detection device 110 may output a second differential signal with a reduced offset voltage in addition to the first differential signal. Thereby, the detection system 100 can detect the rotation direction of the rotating body 10. Next, the detection device 110 that outputs the first differential signal and the second differential signal will be described.

  FIG. 19 shows a fourth configuration example of the detection apparatus 110 according to this embodiment. In the detection apparatus 110 according to the fourth configuration example, substantially the same operations as those of the detection apparatus 110 according to the third configuration example illustrated in FIG. 18 are denoted by the same reference numerals, and description thereof is omitted. The detection device 110 of the fourth configuration example includes a first bridge magnetoresistive element 210 (that is, the first magnetoresistive element 212 and the second magnetoresistive element 214) and a second shape substantially the same as the detection apparatus 110 shown in FIG. The bridge magnetoresistive element 220 (that is, the third magnetoresistive element 222 and the fourth magnetoresistive element 224) is included. The detection device 110 of the fourth configuration example includes a third terminal 350, a fourth terminal 360, a third bridge magnetoresistive element 310 (that is, the fifth magnetoresistive element 312 and the sixth magnetoresistive element 314), and the first A 4-bridge magnetoresistive element 320 (that is, a seventh magnetoresistive element 322 and an eighth magnetoresistive element 324) is further provided.

The third terminal 350 outputs a positive detection signal V _{B +} , and the fourth terminal 360 outputs a negative detection signal V _B− . That is, the third terminal 350 functions as a third differential terminal, the fourth terminal 360 functions as a fourth differential terminal, and functions as a differential terminal pair that outputs a second differential signal. The third bridge magnetoresistive element 310 and the fourth bridge magnetoresistive element 320 differentially detect a change in magnetic flux density accompanying the movement of the rotating body 10. The magnetic sensitive parts of the first bridge magnetoresistive element 210, the second bridge magnetoresistive element 220, the third bridge magnetoresistive element 310, and the fourth bridge magnetoresistive element 320 are arranged in the moving direction of the rotating body 10.

  The first bridge magnetoresistive element 210, the second bridge magnetoresistive element 220, the third bridge magnetoresistive element 310, and the fourth bridge magnetoresistive element 320 overlap at least partially in the width direction in which the magnetosensitive part is provided. Formed as follows. In other words, the fifth magnetoresistive element 312, the sixth magnetoresistive element 314, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324 have at least partly overlapping ranges in which the magnetic sensitive portions are provided in the width direction. In addition, it is desirable that the eight magnetoresistive elements from the first magnetoresistive element 212 to the eighth magnetoresistive element 324 have at least partly overlapping ranges in which the magnetosensitive portions are provided in the width direction.

  Note that each of the fifth magnetoresistive element 312, the sixth magnetoresistive element 314, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324 has a plurality of senses provided at different positions in the moving direction of the rotating body 10. Includes magnetic parts. FIG. 19 shows an example in which the fifth magnetoresistive element 312, the sixth magnetoresistive element 314, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324 each include two magnetosensitive portions. FIG. 19 shows an example in which the eight magnetoresistive elements from the first magnetoresistive element 212 to the eighth magnetoresistive element 324 all overlap in the width direction in which the magnetosensitive part is provided.

  The fifth magnetoresistance element 312 is disposed between the first magnetoresistance element 212 and the second magnetoresistance element 214 in the moving direction of the rotating body 10. The sixth magnetoresistive element 314 is disposed between the second magnetoresistive element 214 and the fourth magnetoresistive element 224 in the moving direction of the rotating body 10. The sixth magnetoresistive element 314 and the fourth magnetoresistive element 224 are formed at a predetermined interval. The eighth magnetoresistive element 324 is disposed between the fourth magnetoresistive element 224 and the third magnetoresistive element 222 in the moving direction of the rotating body 10. The seventh magnetoresistive element 322 is arranged on the opposite side of the third magnetoresistive element 222 from the fourth magnetoresistive element 224 in the moving direction of the rotating body 10.

  That is, the third bridge magnetoresistive element 310 and the fourth bridge magnetoresistive element 320 may be arranged by shifting the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220 in the moving direction of the rotating body 10. desirable. Thus, the detection signals output from the third bridge magnetoresistive element 310 and the fourth bridge magnetoresistive element 320 are shifted from the detection signals output from the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220, respectively. The detection signal has a phase difference corresponding to the determined position.

  Therefore, the detection system 100 including the detection device 110 of the above fourth configuration example can detect the rotation direction of the rotating body 10 by comparing the first differential signal and the second differential signal. Further, the arrangement of the third bridge magnetoresistive element 310 and the fourth bridge magnetoresistive element 320 in the moving direction of the rotating body 10 is similar to the arrangement of the first bridge magnetoresistive element 210 and the second bridge magnetoresistive element 220. Since it can be made to correspond to the distribution of the magnetic field of the generator 20, the offset voltage can be reduced. That is, the detection system 100 including the detection device 110 of the fourth configuration example can accurately detect the rotation operation of the rotating body 10.

  In the detection device 110 of the fourth configuration example described above, the example in which the four magnetosensitive portions from the first bridge magnetoresistive element 210 to the fourth bridge magnetoresistive element 320 are arranged in the moving direction of the rotating body 10 has been described. The configuration is not limited to this. Next, another configuration example of the detection device 110 will be described.

  FIG. 20 shows a detection system 100 including a fourth configuration example of the detection apparatus 110 according to the present embodiment. That is, FIG. 20 shows an example in which the detection system 100 is configured using the detection device 110 of the fourth configuration example shown in FIG. In the detection system 100 shown in FIG. 20, the same reference numerals are given to the substantially same operations as those of the detection system 100 shown in FIG.

  In the detection device 110 of the fourth configuration example, the second magnetoresistive element 214 is disposed at a position shifted from the first magnetoresistive element 212 in the moving direction of the rotating body 10 or in the reverse direction of the moving direction, and from the first terminal 250. The first detection signal is output. The third magnetoresistive element 222 is connected between a second terminal 260 that outputs a second detection signal that forms a differential pair with the first detection signal, and the second potential. The fourth magnetoresistive element 224 is disposed at a position shifted from the third magnetoresistive element 222 in the moving direction of the rotating body 10 or in the direction opposite to the moving direction, and is connected between the second terminal 260 and the first potential. The

  Similarly, in the detection device 110 of the fourth configuration example, the sixth magnetoresistive element 314 is arranged at a position shifted from the fifth magnetoresistive element 312 in the moving direction of the rotating body 10 or in the reverse direction of the moving direction, A third detection signal is output from the terminal 350. The seventh magnetoresistive element 322 is connected between a fourth terminal 360 that outputs a fourth detection signal that forms a differential pair with the third detection signal, and the second potential. The eighth magnetoresistive element 324 is disposed at a position shifted from the seventh magnetoresistive element 322 in the moving direction of the rotating body 10 or in the direction opposite to the moving direction, and is connected between the fourth terminal 360 and the first potential. The

  Thus, the first magnetoresistive element 212 and the second magnetoresistive element 214 are arranged in a symmetrical positional relationship with the third magnetoresistive element 222 and the fourth magnetoresistive element 224 in the moving direction of the rotating body 10. Further, the fifth magnetoresistive element 312 and the sixth magnetoresistive element 314 are arranged in a symmetrical positional relationship with the seventh magnetoresistive element 322 and the eighth magnetoresistive element 324 in the moving direction of the rotating body 10.

  FIG. 21 shows a detection system 100 including a fifth configuration example of the detection apparatus 110 according to the present embodiment. In the detection apparatus 110 according to the fifth configuration example, substantially the same operations as those of the detection apparatus 110 according to the fourth configuration example illustrated in FIGS. 19 and 20 are denoted by the same reference numerals, and description thereof is omitted. In the detection device 110 of the fifth configuration example, the second magnetoresistive element 214 is disposed at a position shifted from the first magnetoresistive element 212 in the moving direction of the rotating body 10 or in the reverse direction of the moving direction, and from the first terminal 250. The first detection signal is output.

  The third magnetoresistive element 222 is connected between a second terminal 260 that outputs a second detection signal that forms a differential pair with the first detection signal, and the second potential. The fourth magnetoresistive element 224 is disposed at a position shifted from the third magnetoresistive element 222 in the moving direction of the rotating body 10 or in the direction opposite to the moving direction, and is connected between the second terminal 260 and the first potential. The The first magnetoresistive element 212, the second magnetoresistive element 214, the third magnetoresistive element 222, and the fourth magnetoresistive element 224 are the first magnetoresistive element 212 and the third magnetic resistor in the moving direction or the direction opposite to the moving direction. A second magnetoresistive element 214 and a fourth magnetoresistive element 224 are disposed between the resistive elements 222.

  In the detection device 110 of the fifth configuration example, the respective magnetoresistive elements are arranged in the first region 712 to the sixth region 724 arranged at substantially equal intervals. For example, the first magnetoresistive element 212 is in the first region 712, the second magnetoresistive element 214 is in the third region 716, the third magnetoresistive element 222 is in the fifth region 722, and the fourth magnetoresistive element 224 is in the third region. They are arranged in the regions 716, respectively. As shown in FIG. 21, for example, when the first magnetoresistive element 212 faces the first tooth 12 of the rotating body 10, the third magnetoresistive element 222 faces the second tooth 14 of the rotating body 10. Moreover, the 2nd magnetoresistive element 214 and the 4th magnetoresistive element 224 are arrange | positioned in the same area | region, and oppose the recessed part of a rotary body.

  Thus, the first magnetoresistive element 212 and the third magnetoresistive element 222 are separated by a distance corresponding to one cycle of the change in the magnetic flux density of the rotating body 10 caused by the eddy current in the moving direction of the rotating body 10. Placed in position. The first magnetoresistive element 212 and the third magnetoresistive element 222 are separated by a distance corresponding to an integer period of the change in magnetic flux density in the rotating body 10 caused by the eddy current in the moving direction or in the direction opposite to the moving direction. It may be arranged.

  In this case, the second magnetoresistive element 214 may be disposed at a position within a half cycle of the change in the magnetic flux density from the first magnetoresistive element 212 in the moving direction or in the direction opposite to the moving direction. The fourth magnetoresistive element 224 may be arranged at a position within a half cycle of the change in the magnetic flux density from the third magnetoresistive element 222 in the moving direction or in the direction opposite to the moving direction. In this case, the interval between the positions where the second magnetoresistive element 214 and the fourth magnetoresistive element 224 are provided may be within ¼ period of the change in the magnetic flux density in the movement direction or in the direction opposite to the movement direction.

  Here, the magnetic field generator 20 generates a magnetic field having a substantially constant magnetic flux density in, for example, the third region 716 and the fourth region 718 that are regions near the center. In this case, the magnetic field generator 20 generates a magnetic field in which the magnetic flux density gradually increases or decreases in the moving direction in the first region 712, the second region 714, the fifth region 722, and the sixth region 724 that are separated from the center. That is, the magnetic field generator 20 applies a magnetic field having a direction of change of magnetic flux density opposite to that of the first magnetoresistive element 212 in the moving direction to the third magnetoresistive element 222.

Therefore, when the rotating body 10 rotates in the direction of the arrow shown in FIG. 21, the resistance value of the first magnetoresistive element 212 among the first magnetoresistive element 212 and the second magnetoresistive element 214 becomes small, and the third magnetoresistive element Of the 222 and fourth magnetoresistive elements 224, the resistance value of the third magnetoresistive element 222 is increased. Accordingly, the first detection signal and the second detection signal generate an offset voltage having the same sign as shown in the following equation.
(Equation 13)
V _{A +} ′ = (V _dd −V _ss ) · (R ₂ ) / (R ₁ + R ₂ −ΔR ₁ ) = V _{A +} + V _OFF1
V _A− ′ = (V _dd −V _ss ) · (R ₃ + ΔR ₃ ) / (R ₃ + R ₄ + ΔR ₃ ) = V _{A +} + V _OFF2

Therefore, it can be seen that the offset voltage generated by the eddy current can be reduced by removing the common-mode noise based on the differential signals V _{A +} 'and V _A- '. Further, the second magnetoresistive element 214 may be disposed more shifted to the first magnetoresistive element 212 side, and both the resistance values of the first magnetoresistive element 212 and the second magnetoresistive element 214 may be reduced. In this case, the fourth magnetoresistive element 224 is correspondingly disposed more shifted to the third magnetoresistive element 222 side, so that the resistance values of both the third magnetoresistive element 222 and the fourth magnetoresistive element 224 are reduced. Increase both. Thereby, the offset voltage generated in the first detection voltage and the second detection voltage can be reduced similarly to the common-mode noise.

  Similarly, the fifth magnetoresistive element 312 is in the second region 714, the sixth magnetoresistive element 314 is in the fourth region 718, the seventh magnetoresistive element 322 is in the sixth region 724, and the eighth magnetoresistive element 324 is in the eighth region. Each of the four areas 718 is arranged. Thereby, when the rotating body 10 rotates in the direction of the arrow shown in FIG. 21, the resistance value of the fifth magnetoresistive element 312 among the fifth magnetoresistive element 312 and the sixth magnetoresistive element 314 decreases, and the seventh magnetoresistive element Of the element 322 and the eighth magnetoresistive element 324, the resistance value of the seventh magnetoresistive element 322 increases. Therefore, it can be seen that the offset voltage generated by the eddy current can also be reduced by removing the in-phase noise from the second differential signal.

  It is desirable that the magnetic field distribution of the magnetic field generation unit 20 and the detection device 110 of the fifth configuration example be configured substantially symmetrically with respect to the magnet center shown in FIG. Next, the layout on the substrate 30 of the detection apparatus 110 of the fifth configuration example will be described.

  FIG. 22 shows a fifth configuration example of the detection apparatus 110 according to this embodiment. FIG. 22 shows an example in which the detection device 110 described in FIG. 21 is formed on the substrate 30. Therefore, the same reference numerals are given to the substantially same operations as those of the detection device 110 shown in FIG. Omitted. The substrate 30 has a first potential terminal 202, a second potential terminal 204, and a first bridge magnetoresistive element 210 (that is, the first magnetoresistive element 212 and the second magnetoresistive element 214) on the surface that should face the rotating body 10. The second bridge magnetoresistive element 220 (ie, the third magnetoresistive element 222 and the fourth magnetoresistive element 224), the third bridge magnetoresistive element 310 (ie, the fifth magnetoresistive element 312 and the sixth magnetoresistive element 314). , A fourth bridge magnetoresistive element 320 (ie, a seventh magnetoresistive element 322 and an eighth magnetoresistive element 324), a first terminal 250, a second terminal 260, a third terminal 350, and a fourth terminal 360 are provided.

  The first bridge magnetoresistive element 210 and the third bridge magnetoresistive element 310 are formed so that at least part of the range in which the magnetosensitive part is provided overlaps in the width direction orthogonal to the moving direction of the rotating body 10. That is, in the first magnetoresistive element 212, the second magnetoresistive element 214, the fifth magnetoresistive element 312, and the sixth magnetoresistive element 314, at least a part of the range in which the magnetosensitive portion is provided overlaps in the width direction. In FIG. 22, the four magnetoresistive elements of the first magnetoresistive element 212, the second magnetoresistive element 214, the fifth magnetoresistive element 312, and the sixth magnetoresistive element 314 are provided with a magnetic sensing portion in the width direction. An example where all ranges overlap is shown.

  Similarly, the second bridge magnetoresistive element 220 and the fourth bridge magnetoresistive element 320 are formed so that the ranges in which the magnetic sensitive portions are provided overlap at least partially in the width direction orthogonal to the moving direction of the rotating body 10. . That is, the third magnetoresistive element 222, the fourth magnetoresistive element 224, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324 overlap at least partially in the range in which the magnetosensitive portion is provided in the width direction. In FIG. 22, the four magnetoresistive elements of the third magnetoresistive element 222, the fourth magnetoresistive element 224, the seventh magnetoresistive element 322, and the eighth magnetoresistive element 324 are provided with a magnetic sensing portion in the width direction. An example where all ranges overlap is shown.

  FIG. 22 shows an example in which the magnetic sensitive parts included in the first bridge magnetoresistive element 210 to the fourth bridge magnetoresistive element 320 are arranged at substantially equal intervals in the moving direction of the rotating body 10. Further, the magnetic sensitive parts of the first bridge magnetoresistive element 210 and the third bridge magnetoresistive element 310 and the magnetic sensitive parts of the second bridge magnetoresistive element 220 and the fourth bridge magnetoresistive element 320 are shifted in the width direction. The example formed is shown.

  Since the detection device 110 of the fifth configuration example arranged as described above also arranges the magnetoresistive element in a region where the magnetic flux density is substantially constant, compared with the detection device 110 of the fourth configuration example, The length can be shortened. In the detection device 110 of the fifth configuration example, the first bridge magnetoresistive element 210 and the third bridge magnetoresistive element 310, and the second bridge magnetoresistive element 220 and the fourth bridge magnetoresistive element 320 are arranged in the width direction. An example in which they are formed in a shifted manner has been described. In this case, as described with reference to FIG. 9, if the rotating body 10 has a defect or the like, an error may occur in the detection result. Therefore, the magnetic sensitive parts included in the first bridge magnetoresistive element 210 to the fourth bridge magnetoresistive element 320 of the detection device 110 of the fifth configuration example may be arranged so that at least a part thereof overlaps in the width direction. Such a detection device 110 will be described next.

  FIG. 23 shows a sixth configuration example of the detection apparatus 110 according to the present embodiment. As described with reference to FIG. 11, the detection device 110 of the sixth configuration example corresponds to the bridge magnetoresistance elements of the first bridge magnetoresistance element 210 to the fourth bridge magnetoresistance element 320 of the detection device 110 of the fifth configuration example. The example arranged in the moving direction of the rotary body 10 is shown. Therefore, in FIG. 23, the same reference numerals are given to the substantially same operations as those of the detection device 110 shown in FIG.

  The magnetic sensitive parts of the first bridge magnetoresistive element 210, the second bridge magnetoresistive element 220, the third bridge magnetoresistive element 310, and the fourth bridge magnetoresistive element 320 are arranged in the moving direction of the rotating body 10. The eight magnetoresistive elements from the first magnetoresistive element 212 to the eighth magnetoresistive element 324 are arranged so that at least partly overlaps the range in which the magnetosensitive part is provided in the width direction. FIG. 23 shows an example in which eight magnetoresistive elements from the first magnetoresistive element 212 to the eighth magnetoresistive element 324 overlap all the ranges in which the magnetosensitive portions are provided in the width direction.

  In the detection device 110 of the sixth configuration example, the magnetoresistive elements arranged in the same region in the detection device 110 of the fifth configuration example are arranged so that the average positions in the movement direction substantially coincide with each other as described in FIG. Deploy. For example, the magnetic sensitive parts included in the second magnetoresistive element 214 and the fourth magnetoresistive element 224 included in the third region 716 have substantially the same average position in the moving direction of the rotating body 10 in the third region 516. Is desirable. For example, the difference in the moving direction of the rotating body 10 between the average position of the plurality of magnetosensitive parts in the second magnetoresistive element 214 and the average position of the plurality of magnetosensitive parts in the fourth magnetoresistive element 224 is adjacent in the moving direction. It is desirable that the distance is less than the distance between the magnetic sensing parts.

  Thereby, the detection apparatus 110 of the sixth configuration example arranges the eight magnetoresistive elements from the first magnetoresistive element 212 to the eighth magnetoresistive element 324 in the moving direction of the rotating body 10, and in the width direction, the magnetosensitive element It can arrange | position so that at least one part of the range in which a part is provided may overlap. Therefore, the detection device 110 of the sixth configuration example reduces the offset voltage generated in the differential signal, and as described in FIG. 11, even if the rotating body 10 has a defect, the rotating operation of the rotating body 10 Can be detected with high accuracy.

  In the detection apparatus 110 according to the above-described embodiment, the shape of the magnetic sensing portion formed on the substrate 30 has been described as a rectangle extending in a direction perpendicular to the moving direction of the rotating body 10, but is not limited thereto. Never happen. The shape of the magnetic sensitive part may be a triangle, a square, a trapezoid, a polygon, a circle, an ellipse, or the like. Moreover, although each magnetoresistive element demonstrated the example which has the said magnetic sensitive part 2 each, it is not limited to this. Each magnetoresistive element may have one or a plurality of magnetic sensing parts.

  Moreover, although the detection system 100 which concerns on the above this embodiment demonstrated providing the rotary body 10 which is a gearwheel as a to-be-detected unit, it is not limited to this. The rotating body 10 is an example of a detected unit that is a detection target provided in the detection system 100. The unit to be detected has concave portions and / or convex portions alternately arranged along the moving direction on the detection device 110 side, and the detection device 110 is provided to face the concave portions and / or convex portions. Any member can be used as long as it can be configured so that the magnetic flux density input to the portion changes.

  The detected unit may be a spur gear, a helical gear, a helical gear, a bevel gear, an internal gear, a crown gear, a screw gear, a worm gear, a sprocket, and a rack or pinion. Further, the detected unit may simply be a member in which convex portions and / or concave portions are formed on a disk-shaped plate portion. In addition, the detected unit may have a plate portion in which a plurality of through-holes facing the detection device 110 side are arranged along the movement direction with the detection device 110.

  In addition, in this embodiment, although the to-be-detected unit demonstrated rotating operation, it is not limited to this. When the detected unit is a rack or the like, the convex portion and / or the concave portion may move in one direction. Further, the detected unit may be fixed and the detection device 110 may move. In this case, the detection device 110 may operate assuming that the detected unit moves relatively. That is, in this embodiment, instead of the expression “movement” of the rotating body 10, it may be expressed as “relative movement” of the rotating body 10.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 Rotating body, 12 1st tooth | gear, 14 2nd tooth | gear, 18 Defect, 20 Magnetic field generation | occurrence | production part, 30 Board | substrate, 40 Power supply, 100 detection system, 110 detection apparatus, 112 1st detection part, 114 2nd detection part, 202 First potential terminal, 204 Second potential terminal, 206 Second potential terminal, 208 First potential terminal, 210 First bridge magnetoresistive element, 212 First magnetoresistive element, 214 Second magnetoresistive element, 220 Second bridge Magnetoresistive element, 222 third magnetoresistive element, 224 fourth magnetoresistive element, 250 first terminal, 260 second terminal, 310 third bridge magnetoresistive element, 312 fifth magnetoresistive element, 314 sixth magnetoresistive element, 320 4th bridge magnetoresistive element, 322 7th magnetoresistive element, 324 8th magnetoresistive element, 350 3rd terminal, 360 4th terminal, 5 2 First region, 514 Second region, 516 Third region, 518 Fourth region, 530 Amplifier circuit, 612 First region, 614 Second region, 616 Third region, 618 Fourth region, 712 First region, 714 2nd area, 716 3rd area, 718 4th area, 722 5th area, 724 6th area

Claims (15)

A detection device that detects a change in magnetic flux density associated with relative movement of a detected unit,
A first magnetic sensor connected between a first terminal for outputting a first detection signal and a first potential;
A second magnetic sensor disposed at a position shifted from the first magnetic sensor in a relative movement direction of the detected unit or in a direction opposite to the relative movement direction, and connected between the first terminal and a second potential;
A magnetic field application unit configured to apply a magnetic field in which a magnetic flux density gradually increases or decreases in the relative movement direction to the first magnetic sensor and the second magnetic sensor;
A detection device comprising: The magnetic field application unit includes a plate-shaped magnet to be disposed to face the detected unit with the first magnetic sensor and the second magnetic sensor interposed therebetween,
The detection device according to claim 1, wherein the first magnetic sensor and the second magnetic sensor are arranged so as to be shifted from the center of the plate-shaped magnet in the relative movement direction or in a direction opposite to the relative movement direction. A third magnetic sensor connected between a second terminal that outputs a second detection signal that forms a differential pair with the first detection signal, and the second potential;
A fourth magnetic sensor disposed at a position displaced from the third magnetic sensor in a relative movement direction of the detected unit or in a direction opposite to the relative movement direction, and connected between the second terminal and a first potential;
Further comprising
The magnetic field application unit is configured such that the direction of change in magnetic flux density is opposite in the relative movement direction between the set of the first magnetic sensor and the second magnetic sensor and the set of the third magnetic sensor and the fourth magnetic sensor. The detection device according to claim 1, wherein a magnetic field is applied.   The first magnetic sensor, the second magnetic sensor, the third magnetic sensor, and the fourth magnetic sensor may be configured such that the first magnetic sensor, the second magnetic sensor, or the second magnetic sensor is in the relative movement direction or in a direction opposite to the relative movement direction. The detection device according to claim 3, wherein a sensor, the fourth magnetic sensor, and the third magnetic sensor are arranged in this order.   The set of the first magnetic sensor and the second magnetic sensor, and the set of the third magnetic sensor and the fourth magnetic sensor are arranged in the detected unit in the relative movement direction or in the direction opposite to the relative movement direction. The detection device according to claim 3, wherein the detection device is disposed at a position separated from one period of change in magnetic flux density.   The set of the first magnetic sensor and the second magnetic sensor and the set of the third magnetic sensor and the fourth magnetic sensor exceed the one period in the relative movement direction or in the opposite direction of the relative movement direction. The detection apparatus according to claim 5, wherein the detection apparatus is disposed at a position separated by a distance of less than 1.5 cycles. A third magnetic sensor connected between a second terminal that outputs a second detection signal that forms a differential pair with the first detection signal, and the second potential;
A fourth magnetic sensor disposed at a position displaced from the third magnetic sensor in a relative movement direction of the detected unit or in a direction opposite to the relative movement direction, and connected between the second terminal and a first potential;
Further comprising
The first magnetic sensor, the second magnetic sensor, the third magnetic sensor, and the fourth magnetic sensor may be configured such that the first magnetic sensor and the third magnetic sensor in the relative movement direction or in the direction opposite to the relative movement direction. The second magnetic sensor and the fourth magnetic sensor are disposed between the sensors,
The detection device according to claim 1, wherein the magnetic field application unit applies a magnetic field having a magnetic flux density change direction opposite to that of the first magnetic sensor in the relative movement direction to the third magnetic sensor. The first magnetic sensor and the third magnetic sensor are disposed at positions separated by a distance corresponding to an integer period of a change in magnetic flux density in the detected unit in the relative movement direction or the reverse direction of the relative movement direction,
The second magnetic sensor is disposed at a position within a half cycle from the first magnetic sensor in the relative movement direction or the reverse direction of the relative movement direction,
The detection device according to claim 7, wherein the fourth magnetic sensor is arranged at a position within a half cycle from the third magnetic sensor in the relative movement direction or in a direction opposite to the relative movement direction.   The detection according to claim 7 or 8, wherein the interval between the positions where the second magnetic sensor and the fourth magnetic sensor are provided is within a quarter cycle in the relative movement direction or in a direction opposite to the relative movement direction. apparatus.   10. The detection according to claim 3, wherein each of the first magnetic sensor, the second magnetic sensor, the third magnetic sensor, and the fourth magnetic sensor includes a semiconductor magnetoresistive element in a magnetic sensitive part. apparatus. The detected unit;
A detection system comprising: the detection device according to any one of claims 1 to 10 provided to face the detected unit.   The detection system according to claim 11, wherein the detected unit has concave portions and convex portions alternately arranged along the relative movement direction on the detection device side.   The detection system according to claim 12, wherein the detected unit is a gear.   The detection system according to claim 11, wherein the detected unit includes a plate portion in which a plurality of through holes facing the detection device side are arranged along the relative movement direction.   The detection system according to claim 11, further comprising a magnetic field generation unit provided on the opposite side of the detected unit in the detection device.

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