JP5012424B2 - Rotation angle detection device and rotation angle detection method - Google Patents

Description

  The present invention relates to a rotation angle detection device and a rotation angle detection method.

As a conventional technique for measuring the rotation angle of the rotation shaft by magnetism, a pair of stationary magnets opposed to each other with the rotation shaft interposed therebetween, and one of the magnets disposed between the pair of magnets and provided on the rotation shaft Some have a magnetic sensor, and a rotating magnetic sensor detects a magnetic field between magnets. In such a device, the magnetic sensor disposed between the pair of magnets rotates with the rotation shaft, and the output signal from the magnetic sensor changes according to the rotation. You can know the rotation angle. An example of an apparatus for measuring the rotation angle by magnetism is disclosed in Patent Document 1, for example.
Japanese Patent No. 3264151

  However, in the rotation angle detection device having the above-described configuration, since there is one magnetic sensor that detects a magnetic field, high measurement accuracy can be obtained only in an angle range of ± 45 °. For this reason, it is difficult to detect the rotation angle with high accuracy through one rotation of the rotation shaft.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a rotation angle detection device and a rotation angle detection method that can accurately detect the rotation angle through one rotation of the rotation shaft.

  In order to solve the above-described problem, a rotation angle detection device according to the present invention is a rotation angle detection device that detects the rotation angle of a rotation shaft, and is a pair of magnetic field forming members that are juxtaposed in the radial direction of the rotation shaft and face each other. And a plurality of magnetic sensors juxtaposed in the circumferential direction of the rotation axis over the entire circumference around the rotation axis, and according to the rotation of the rotation axis, the magnetic field generation unit and the plurality of magnetic fields The plurality of magnetic sensors are positioned between the rotation locus of one of the magnetic field forming members and the rotation locus of the other magnetic field forming member in the magnetic field generation unit, or the plurality of magnetic sensors are rotated relative to each other. Of the pair of magnetic field forming members is located outside the radial direction of the rotation axis. Magnetic field generating member The angle formed by a straight line connecting one end and the center of the rotating shaft and a straight line connecting the other end of the magnetic field generating member located outside the radial direction of the rotating shaft and the center of the rotating shaft among the pair of magnetic field forming members is The adjacent magnetic sensors are larger than the angle formed around the rotation axis, and the magnetic sensor has a first magnetoresistive element, and the magnetization direction of the pinned layer of the first magnetoresistive element is It intersects with the radial direction of the rotating shaft.

  The rotation angle detection method according to the present invention is a method for detecting the rotation angle of the rotation shaft, and includes a magnetic field generation unit that generates a magnetic field by a pair of magnetic field forming members juxtaposed in the radial direction of the rotation shaft and facing each other. The magnetic field generation unit and the plurality of magnetic sensors are relatively rotated according to the rotation of the rotation shaft, and the plurality of magnetic sensors are arranged on one of the magnetic field forming members of the magnetic field generation unit. It is located between the rotation trajectory and the rotation trajectory of the other magnetic field forming member, or the rotation trajectories of the plurality of magnetic sensors pass between one magnetic field forming member and the other magnetic field forming member in the magnetic field generator. A straight line connecting one end of the magnetic field generating member located outside the radial direction of the rotating shaft and the center of the rotating shaft, of the pair of magnetic field forming members juxtaposed in the circumferential direction of the rotating shaft over the entire circumference around the rotating shaft And a pair of magnetic field formation Among the materials, the angle formed by the other end of the magnetic field generating member positioned outside the radial direction of the rotation axis and the straight line connecting the centers of the rotation axes is larger than the angle formed by adjacent magnetic sensors around the rotation axis. The magnetization direction of the pinned layer of the first magnetoresistive effect element included in the magnetic sensor intersects with the radial direction of the rotation axis, and the magnetic field is detected by the first magnetoresistance effect element, so that the rotation angle of the rotation axis is It is characterized by detecting.

  In the rotation angle detection device and the rotation detection methods described above, the plurality of magnetic sensors are positioned between the rotation locus of one magnetic field forming member and the rotation locus of the other magnetic field forming member in the magnetic field generation unit, or The rotation trajectories of the plurality of magnetic sensors are juxtaposed in the circumferential direction of the rotation axis so as to pass between one magnetic field forming member and the other magnetic field forming member in the magnetic field generation unit. Thereby, when each magnetic sensor passes through each magnetic sensor or each magnetic sensor passes through the magnetic field generator, an output signal proportional to the rotation angle can be obtained from each magnetic sensor. By synthesizing the output signal, the rotation angle can be obtained with high accuracy through one rotation of the rotation shaft.

  In the rotation angle detection device, the plurality of magnetic sensors further include a second magnetoresistance effect element, and the magnetization direction of the pinned layer of the second magnetoresistance effect element is along the radial direction of the rotation axis. It may be characterized by being. In the output signal output from the first magnetoresistive element, the potential when passing through the center of the magnetic field generation unit may be equal to the potential at a location other than the magnetic field generation unit. In such a case, the second magnetoresistive effect element outputs almost no signal at a place other than the magnetic field generator, so that it is detected at the potential detected at the first and second magnetic field generators and at other places. Can be distinguished from the potential. Thereby, a rotation angle can be detected suitably.

  The rotation angle detection device may be characterized in that the pair of magnets in the magnetic field generation unit has a shape that is curved in an arc shape along the circumferential direction of the rotation axis. Thereby, the distance between the magnetic sensor and the pair of magnets becomes substantially equal from one end of the magnet to the other end, and the magnitude of the magnetic field around the magnetic sensor can be made constant. Or a pair of magnet in a magnetic field generation | occurrence | production part may have a shape extended | stretched along the direction which cross | intersects the radial direction of a rotating shaft.

  It should be noted that the pair of magnetic field forming members referred to in the present application may be any member that generates a substantially parallel magnetic field, and a pair of permanent magnets are juxtaposed in the radial direction, or a permanent magnet and a yoke are juxtaposed in the radial direction. There may be. Alternatively, a member in which a plurality of magnets are bonded in parallel to the yoke may be juxtaposed in the radial direction.

  According to the rotation angle detection device and the rotation angle detection method of the present invention, the rotation angle can be detected with high accuracy through one rotation of the rotation shaft.

[First embodiment]
Hereinafter, embodiments of a rotation angle detection device and a rotation angle detection method according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a diagram showing a first embodiment of a rotation angle detection device according to the present invention. FIG. 1A shows a plan view of the rotation angle detection device 1, and FIG. 1B shows a side cross-sectional view taken along the line I-I shown in FIG. In FIG. 1A, the axial direction of the rotation axis R is a direction perpendicular to the paper surface, and FIG. 1A is a view of the rotation angle detection device 1 viewed from the axial direction of the rotation axis R. Further, in FIG. 1B, the axial direction of the rotation axis R extends up and down in the drawing, and FIG. 1B shows a cross section including the central axis of the rotation axis R.

  The rotation angle detection device 1 according to the present embodiment is a device that is attached to a rotation shaft R and detects the rotation angle of the rotation shaft R. As shown in FIGS. 1A and 1B, the rotation angle detection device 1 includes a magnetic field generator 2, magnetic sensors 3 a to 3 h, and a support member 15. The support member 15 is a resin-made circular (or substantially square) flat plate-like member. In the central portion of the support member 15, the rotation axis R is inserted so that the axial direction thereof matches the thickness direction of the support member 15, and the support member 15 and the rotation shaft R are fixed to each other. . The magnetic field generator 2 is fixed to the support member 15 and rotates together with the rotation axis R. Note that the relative position of the magnetic field generator 2 is constant regardless of the rotation of the rotation axis R.

  The magnetic field generator 2 is configured by a pair of magnets 4 and 5 that are juxtaposed in the radial direction of the rotation axis R. The magnets 4 and 5 are rod-shaped ferrite magnets or neodymium magnets that extend along a direction that intersects the radial direction of the rotation axis R. The longitudinal width of the magnets 4 and 5 is a width that covers an angle that is 10 ° or more larger than the angle detected by the magnetic sensors 3a to 3h (that is, the angle formed by the magnetic sensors around the rotation axis). If the detection angle of ˜3h is 45 °, for example, the magnets 4 and 5 have a width that can cover 55 ° or more. With this configuration, at least one magnetic field detecting means exists between the substantially parallel magnetic fields formed by the pair of magnets 4 and 5. Magnets 4 and 5 of magnetic field generating unit 2 have N poles 4a and 5a on one side surface in the longitudinal direction intersecting the radial direction of rotation axis R, and S poles 4b and 5b on the other side surface. The magnetic field generator 2 generates a magnetic field by being fixed to the support member 15 so that the N pole 4a and the S pole 5b of the magnets 4 and 5 face each other, and the direction of the magnetic field is outside the rotation axis R. The direction.

  The magnetic sensors 3 a to 3 h are sensors for detecting a magnetic field between the magnets 4 and 5. The magnetic sensors 3a to 3h are located between the rotation locus of the magnet 4 and the rotation locus of the magnet 5, are juxtaposed in the circumferential direction of the rotation axis R, and are supported and fixed at a fixed position by a support structure (not shown). It is stationary regardless of the rotation of the rotation axis R. In the present embodiment, the magnetic sensors 3a to 3h are arranged over the entire circumference so that circumferential positions of adjacent magnetic sensors form an angle of 45 ° around the rotation axis. FIG. 2 shows the configuration of the magnetic sensors 3a to 3h used in this embodiment. As shown in FIG. 2, the magnetic sensors 3 a to 3 h include at least giant magnetoresistive (GMR: Giant Magneto Resistive) elements 20 and 21. The GMR elements 20 and 21 are arranged adjacent to each other in the same package. The pair of GMR elements 20 and 21 correspond to the first and second magnetoresistance effect elements in the present embodiment, and the magnetization direction B1 of the pinned layer 20a of the GMR element 20 intersects the radial direction of the rotation axis R ( The magnetization direction B1 of the pinned layer 21a of the GMR element 21 is fixed along the radial direction of the rotation axis R (preferably parallel to the radial direction).

  Next, the configuration of the magnetic sensors 3a to 3h will be described in more detail. FIG. 3 is a diagram showing a conceptual configuration and operation of the GMR element. The GMR element 22 shown in FIG. 3 includes a pinned layer 22a whose magnetization direction is fixed by exchange coupling of a ferromagnetic layer and an antiferromagnetic layer, and a free layer 22b which is made of a ferromagnetic layer and whose magnetization direction is changed by a surrounding magnetic field. , And the electron induction layer 22c sandwiched between the pinned layer 22a and the free layer 22b. When the magnetization direction B1 of the pinned layer 22a and the magnetization direction B2 of the free layer 22b are parallel to each other, the electrical resistance of the element is minimized, and the magnetization direction B1 of the pinned layer 22a and the magnetization direction B2 of the free layer 22b are mutually In the case of being antiparallel, the electric resistance value of the element is maximized. Therefore, the direction of the magnetic field can be known by detecting the electric resistance value of the GMR element 22. For example, consider the case where the magnetization direction B1 of the pinned layer 22a is fixed in the direction from the magnet 16 to the magnet 17 as shown in FIGS. 3 (a) and 3 (b). When the GMR element 22 is sandwiched between the N pole 16a and the S pole 17b of the magnets 16 and 17 as shown in FIG. 3A, the magnetization direction B2 of the free layer 22b changes according to the surrounding magnetic field. From the magnet 17 to the south pole 17b, parallel to the magnetization direction B1, and the electric resistance value is minimized. Conversely, when the GMR element 22 is sandwiched between the south pole 16b of the magnet 16 and the north pole 17a of the magnet 17 as shown in FIG. 3B, the magnetization direction B2 of the free layer 22b is in accordance with the surrounding magnetic field. The direction from the N pole 17a to the S pole 16b of the magnet 16 is antiparallel to the magnetization direction B1, and the electric resistance value is maximized.

  4A and 4B are diagrams showing the setting of the magnetization directions of the pinned layers 20a and 21a in the GMR elements 20 and 21 shown in FIG. FIG. 5 is a graph conceptually showing an output signal value corresponding to the angle of the magnetization direction B2 with respect to the magnetization direction B1 of the pinned layers 20a and 21a of the GMR elements 20 and 21. In FIG. 5, the state shown in FIG. 4A, when the magnetization direction B1 of the pinned layer 20a is set along the direction orthogonal to the radial direction of the rotation axis R, the magnetization direction B1 of the pinned layer 20a is a magnetic field at a rotation angle of 0 °. And the output signal from the GMR element 20 has an intermediate value as shown in FIG. In such a case, the GMR element 20 outputs a signal substantially proportional to the rotation angle in a portion surrounded by a square of the graph from the intermediate value in FIG. 5, that is, in a range of ± 22.5 °.

  When the magnetization direction B1 of the pinned layer 21a is set parallel to the radial direction of the rotation axis R as shown in FIG. 4B, the magnetization direction B1 of the free layer 21b is the direction of the magnetic field (N This is the opposite of pole 4a to S pole 5b. In such a case, the GMR element 21 outputs the minimum value of the graph shown in FIG. 5, but this signal is ignored.

  In the graph shown in FIG. 5, the GMR element 20 of the magnetic sensors 3a to 3h is substantially proportional to the angle in the range of an angular width of 45 ° such as 337.5 ° to 22.5 ° or 157.5 ° to 202.5 °. Output a signal. FIG. 6 shows a graph in which signals (voltages) output from the magnetic sensors 3a to 3h are synthesized. The vertical axis in FIG. 6 is the voltage [V] of the output signal, and the horizontal axis is the rotation angle [°]. The range of A on the vertical axis is the range of output signals detected by the GMR elements 20 of the magnetic sensors 3a to 3h in the magnetic field generator 2, and the correlation between the output signals from the magnetic sensors 3a to 3h and the rotation angles is shown. In order to synthesize linearly, a bias is added to the output signal as necessary. As shown in FIG. 6, for example, A1 is an angle range to which a signal (voltage) output from the magnetic sensor 5a is applied in the magnetic field generator 2, and A2 is a signal output from the magnetic sensor 5b in the magnetic field generator 2. Is the angular range to which is applied. Similarly, A5 is an angle range to which a signal output from the magnetic sensor 5e is applied in the magnetic field generator 2, and A6 is an angle range to which a signal output from the magnetic sensor 5f is applied in the magnetic field generator 2. . Thus, the detected output signal is amplified in the differential amplifier circuit, and a bias is applied at intervals of 45 °, whereby a signal proportional to the rotation angle can be obtained over 360 ° as shown in FIG. .

  Next, the detection of the magnetic field by the GMR element 21 will be described. The output signal of the GMR element 21 is different when passing between the pair of magnets 4 and 5 of the magnetic field generator 2 and when passing through other locations. That is, as described in the description of FIG. 4B, when the GMR element 21 passes through the first magnetic field generator 2, the magnetic field and the magnetization direction B1 of the pinned layer 21a are in an antiparallel state. The output signal from the GMR element 21 has a minimum value. On the other hand, when the GMR element 21 passes through the second magnetic field generating unit 3, the magnetic field and the magnetization direction B1 of the pinned layer 21a are in a parallel state, so that the output signal from the GMR element 21 has a maximum value.

  Here, in the GMR element 20, the midpoint potential (portion C in FIG. 5) when passing through the center of the magnetic field generation unit 2 may be equal to the potential at a place other than the magnetic field generation unit 2. At this time, the output signal of the GMR element 21 is hardly obtained at a place other than the magnetic field generator 2. As a result, the GMR element 21 detects the midpoint potential detected by the GMR element 20 in the first and second magnetic field generators 2 and 3 and the potential detected outside the first and second magnetic field generators 2 and 3. Can be distinguished.

  The rotation angle detection method according to the present embodiment can be suitably implemented using the rotation angle detection device 1 having the above configuration. That is, this is a method for detecting the rotation angle of the rotation axis R, in which the magnetic field generator 2 that generates a magnetic field by a pair of magnets 4 and 5 that are juxtaposed in the radial direction of the rotation axis R is opposed to the circumference of the rotation axis R. The magnetic field generator 2 and the plurality of magnetic sensors 3a to 3h are rotated relative to each other according to the rotation of the rotation axis R so that the plurality of magnetic sensors 3a to 3h Is located between the rotation locus of the magnet 4 and the rotation locus of the other magnet 5, or the rotation locus of the plurality of magnetic sensors 3a to 3h is Are arranged side by side in the circumferential direction of the rotation axis R over the entire circumference around the rotation axis R, and an angle formed by one end and the other end of the rotation axis R around the rotation axis R is adjacent to each other. The angle formed by the magnetic sensors 3a-3h around the rotation axis R Also increased, the magnetization direction B1 of the pinned layer 20a of the GMR elements 20 to cross the radial direction of the rotating shaft R, by detecting the magnetic field by the GMR element 20 detects the rotation angle of the rotation axis R.

  In the rotation angle detection device 1 and the rotation angle detection method of the present embodiment, the plurality of magnetic sensors 3 a to 3 h are positioned between the rotation locus of one magnet 4 and the rotation locus of the other magnet 5 in the magnetic field generator 2. In this manner, they are juxtaposed in the circumferential direction of the rotation axis R. Thereby, when the magnetic field generation unit 2 passes through the magnetic sensors 3a to 3h, an output signal proportional to the rotation angle can be obtained from each of the magnetic sensors 3a to 3h. Therefore, the output signal from each of the magnetic sensors 3a to 3h. By synthesizing the rotation angle, the rotation angle can be obtained with high accuracy through one rotation of the rotation axis R.

  Next, a description will be given of the results of the trial production of the rotation angle detection device 1 of the present embodiment by the inventor and the detection of the rotation angle of the rotation axis R.

  FIG. 7A is a graph showing output signals (voltages) at 157.5 ° to 202.5 ° from the GMR elements 20 of the magnetic sensors 3a to 3h in the arrangement shown in FIG. FIG. 7A also shows ideal calculated values. FIG. 7B is a graph showing the angle error [°] between the output signal of the GMR element 20 shown in FIG. 7A and the ideal value. It can be seen that there is no significant difference between the actual measurement value and the calculated value in the range of 157.5 ° to 202.5 °. Also in the angle error, the difference from the ideal value is about ± 0 · 40 [°], and there is almost no difference from the ideal calculated value. Therefore, as shown in FIG. 1, the magnetic sensors 3a to 3h are arranged, and the magnetization direction B1 of the pinned layer 20a of the GMR element 20 is set perpendicular to the radial direction of the rotation axis R, whereby the magnetic sensor 3a. It was found that the output signal from ~ 3h approaches the ideal value.

  FIG. 8A is a graph showing output signals (voltages) at 337.5 ° to 22.5 ° from the GMR elements 20 of the magnetic sensors 3a to 3h in the arrangement shown in FIG. FIG. 8A also shows ideal calculated values. FIG. 8B is a graph showing the angle error [°] between the output signal of the GMR element 20 shown in FIG. 8A and the ideal value. It can be seen that there is almost no difference between the measured value and the calculated value even in the range of 337.5 ° to 22.5 °. Also in the angle error, the difference from the ideal value is approximately ± 0 · 50 [°], and it can be seen that the detected rotation angle of the rotating shaft is close to the ideal calculated value. Therefore, the magnetic sensors 3a to 3h are arranged as shown in FIG. 1, and the magnetization direction B1 of the pinned layer 20a of the GMR element 20 is set to be perpendicular to the radial direction of the rotation axis R. It was found that the output signal from 3h approaches the ideal value.

  FIG. 9 is a diagram showing an HR (magnetic field-electric resistance) curve of the GMR element 20. In this embodiment, the rotation angle of the rotation axis R is detected using the magnetic field only on the saturation region side in the HR curve of the GMR element 20. As shown in FIG. 9, the saturation region is, for example, a straight line when the HR curve is approximated by a straight line when the GMR element 20 is 180 ° to ± 22.5 ° (157.5 °, 202.5 °). A point deviating from L is defined as an inflection point and is an area outside the inflection point. The GMR element 20 sets only the magnetic field on the saturation region side as a detection target. FIG. 10 is a graph showing an error between the detected value of the rotation angle in the saturated region and the non-saturated region of the GMR element 20 and an ideal calculated value. As shown in FIG. 10, the error of the rotation angle detected in the non-saturation region is within a range of ± 2.50 [°] with respect to the calculated value, whereas the error of the rotation angle detected in the saturation region. The error is within a range of ± 0.50 [°].

[Second Embodiment]
Next, a second embodiment of a rotation angle detection device and a rotation angle detection method according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  11A and 11B are views showing a second embodiment of the rotation angle detection device according to the present invention. FIG. 11A shows a plan view of the rotation angle detection device 10, and FIG. Side surface sectional drawing along the XI-XI line shown in FIG. 11A, the axial direction of the rotation axis R is a direction perpendicular to the paper surface, and FIG. 11A is a view of the rotation angle detection device 1 viewed from the axial direction of the rotation axis R. Further, in FIG. 11B, the axial direction of the rotation axis R extends up and down in the drawing, and FIG. 11B shows a cross section including the central axis of the rotation axis R.

  As shown in FIGS. 11A and 11B, the rotation angle detection device 10 according to the second embodiment has a shape in which the shape of the magnet is curved in an arc shape along the circumferential direction of the rotation axis R. This is different from the first embodiment.

  That is, the rotation angle detection device 10 according to the second embodiment includes the magnetic field generation unit 30, the magnetic sensors 3a to 3h, and the support member 15. The support member 15 is a resin-made circular (or substantially square) flat plate-like member. In the central portion of the support member 15, the rotation axis R is inserted so that the axial direction thereof matches the thickness direction of the support member 15, and the support member 15 and the rotation shaft R are fixed to each other. . The magnetic field generator 30 is fixed to the support member 15 and rotates together with the rotation axis R. The relative position of the magnetic field generator 30 is constant regardless of the rotation of the rotation axis R.

  The magnetic field generator 30 includes a pair of magnets (magnetic field forming members) 31 and 32 that are juxtaposed in the radial direction of the rotation axis R. The magnetic field generator 30 is disposed in the circumferential direction of the rotation axis R. The magnets 31 and 32 are ferrite magnets or neodymium magnets.

  Since the rotation angle detection device 10 having the above-described configuration is the magnets 31 and 32 that are curved in an arc shape along the circumferential direction of the rotation axis R, the distance between the magnetic sensors 3a to 3h and the pair of magnets is It becomes almost equal from one end of the magnet to the other end, and the magnitude of the magnetic field around the magnetic sensors 3a to 3h can be made constant. As a result, as in the first embodiment, the rotation angle can be detected with high accuracy through one rotation angle.

  The rotation angle detection device and the rotation angle detection method according to the present invention are not limited to the above-described embodiments, and various other modifications are possible. For example, in the said embodiment, although it was set as the structure which rotates the magnetic field generation | occurrence | production part 1 in the said embodiment, it is good also as a structure which rotates several magnetic sensors 3a-3h. In this case, the magnetic sensors 3 a to 3 h are arranged so that the rotation trajectories of the plurality of magnetic sensors 3 a to 3 h pass between the one magnet 4 and the other magnet 5 in the magnetic field generator 2.

It is a figure which shows the structure of 1st Embodiment of the rotation angle detection apparatus by this invention. (A) The top view of the rotation angle detection apparatus is shown. (B) Side surface sectional drawing along the II line | wire shown to (a) is shown. It is a figure which shows the structure of the magnetic sensor used in this embodiment. It is a figure which shows the notional structure and effect | action of a GMR element. (A) (b) It is a figure which shows the example of a setting of the magnetization direction of the pin layer in the GMR element shown in FIG. It is a graph which shows notionally the output signal value from the GMR element corresponding to the setting of Fig.4 (a). It is a graph which shows the result of having combined the signal outputted from each magnetic sensor. (A) It is a graph which shows the output signal from a GMR element in the arrangement | positioning shown in FIG. (B) It is a graph which shows the angle error of the output signal of the GMR element shown to (a), and an ideal value. (A) It is a graph which shows the output signal from a GMR element in the arrangement | positioning shown in FIG. (B) It is a graph which shows the angle error of the output signal of the GMR element shown to (a), and an ideal value. It is a figure which shows the HR (magnetic field-electric resistance) curve of a GMR element. It is a graph which shows the difference | error of the detected value of the rotation angle in the saturation area | region and non-saturation area | region of a GMR element, and an ideal calculation value. It is a figure which shows the structure of 2nd Embodiment of the rotation angle detection apparatus by this invention. (A) The top view of the rotation angle detection apparatus is shown. (B) Side surface sectional drawing along the XI-XI line shown to (a) is shown.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rotation angle detection apparatus, 2 ... Magnetic field generation part, 3a-3h ... Magnetic sensor, 4,5 ... Magnet, 20 ... GMR element (1st magnetoresistive effect element), 21 ... GMR element (2nd magnetoresistance) Effect element), 22 ... GMR element, 20a to 22a ... pinned layer, R ... rotation axis, B1 ... magnetization direction.

Claims (5)

A rotation angle detection device for detecting a rotation angle of a rotation shaft,
A magnetic field generator that generates a magnetic field by a pair of magnetic field forming members arranged in parallel in the radial direction of the rotating shaft;
A plurality of magnetic sensors juxtaposed in the circumferential direction of the rotating shaft over the entire circumference around the rotating shaft;
With
According to the rotation of the rotation shaft, the magnetic field generation unit and the plurality of magnetic sensors rotate relatively,
The plurality of magnetic sensors are located between the rotation locus of one of the magnetic field forming members and the rotation locus of the other magnetic field forming member in the magnetic field generation unit, or the rotation locus of the plurality of magnetic sensors is The magnetic field generator is disposed so as to pass between one of the magnetic field forming members and the other of the magnetic field forming members,
Of the pair of magnetic field forming members, a straight line connecting one end of the magnetic field generating member located outside the radial direction of the rotating shaft and the center of the rotating shaft, and the rotating shaft of the pair of magnetic field forming members. The angle formed between the other end of the magnetic field generating member located outside the radial direction and the straight line connecting the centers of the rotation axes is larger than the angle formed between adjacent magnetic sensors around the rotation axis. And
The magnetic sensor includes a first magnetoresistive effect element, and the magnetization direction of the pinned layer of the first magnetoresistive effect element intersects the radial direction of the rotation axis. Rotation angle detector. The plurality of magnetic sensors further include a second magnetoresistive element,
The rotation angle detection device according to claim 1, wherein the magnetization direction of the pinned layer of the second magnetoresistive element is along the radial direction of the rotation axis.   The rotation angle detection device according to claim 1, wherein the pair of magnets in the magnetic field generation unit has a shape that is curved in an arc shape along a circumferential direction of the rotation shaft.   The rotation angle detection device according to claim 1, wherein the pair of magnets in the magnetic field generation unit has a shape extending along a direction intersecting a radial direction of the rotation shaft. A method for detecting a rotation angle of a rotation axis,
A magnetic field generator that generates a magnetic field by a pair of the magnetic field forming members that are juxtaposed in the radial direction of the rotary shaft and arranged in the circumferential direction of the rotary shaft is arranged, and the magnetic field is generated according to the rotation of the rotary shaft. A generator and a plurality of magnetic sensors are relatively rotated, and the plurality of magnetic sensors are placed between a rotation locus of one of the magnetic field forming members and a rotation locus of the other magnetic field forming member in the magnetic field generation unit. Or the rotation trajectories of the plurality of magnetic sensors pass over the entire circumference around the rotation axis so as to pass between one magnetic field forming member and the other magnetic field forming member in the magnetic field generation unit. Juxtaposed in the circumferential direction of the rotating shaft,
Of the pair of magnetic field forming members, a straight line connecting one end of the magnetic field generating member located outside the radial direction of the rotating shaft and the center of the rotating shaft, and the rotating shaft of the pair of magnetic field forming members. The angle formed by the other end of the magnetic field generating member located outside the radial direction and the straight line connecting the centers of the rotation axes is larger than the angle formed by the adjacent magnetic sensors around the rotation axis,
The magnetization direction of the pinned layer of the first magnetoresistive effect element included in the magnetic sensor intersects the radial direction of the rotation axis, and the magnetic field is detected by the first magnetoresistance effect element, thereby A method of detecting a rotation angle, comprising detecting the rotation angle.

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