JP6210596B2 - Rotation detector - Google Patents

Description

  The present invention relates to a rotation detection device that detects rotation of a gear-like magnetic body.

  Patent Document 1 listed below discloses a rotation detection device configured to include a gear-shaped magnetic body, a magnet, and a magnetic sensor. FIG. 16 is a perspective view of a conventional rotation detection device described in Patent Document 1. In FIG.

  As shown in FIG. 16, the gear-shaped magnetic body 161 includes a ring-shaped magnetic body 167 and a plurality of convex portions 162 provided on the outer periphery of the ring-shaped magnetic body 167. A concave portion 163 is provided between the plurality of convex portions 162, a magnet 133 is disposed on the upper surface side of the convex portion 162 or the concave portion 163, and a magnetic sensor is disposed on the lower surface side of the convex portion 162 or the concave portion 163. 112 is arranged.

  The magnetic sensor 112 uses a magnetoresistive effect element using a giant magnetoresistive effect (GMR (Gianto Magneto Resistance) effect), and the magnetic field detection direction of the magnetic sensor 112 is the radial direction of the gear-like magnetic body 161 or the rotation axis. It arrange | positions so that it may become a direction (Y direction or Z direction shown in FIG. 16).

  When the gear-shaped magnetic body 161 rotates, the direction and strength of the magnetic field acting on the magnetic sensor 112 change between when the convex portion 162 faces the magnetic sensor 112 and when the concave portion 163 faces. Rotation detection can be performed.

Japanese Patent No. 5144803

  However, the intensity of the magnetic field acting on the magnetic sensor 112 depends on the size of the gap between the magnetic sensor 112 and the gear-like magnetic body 161 and the distance between the magnetic sensor 112 and the magnet 133. Therefore, in the rotation detection device 101 of the conventional example, when the gap size changes due to the vertical displacement of the gear-like magnetic body 161 or the variation in the installation of the magnetic sensor 112, the strength of the magnetic field acting on the magnetic sensor 112 changes. The problem that detection accuracy falls arises.

  Furthermore, since the magnetoresistive effect element detects a magnetic field in the magnetoresistive effect film surface that exhibits the magnetoresistive effect, the magnetic sensor 112 can be installed with the magnetic field detection direction directed in the height direction (rotational axis direction). Have difficulty. In order to set the magnetic field detection direction to the height direction, the substrate on which the magnetoresistive film is formed must be set up vertically with respect to the surface formed by the gear-like magnetic body 161. Thus, when it stands upright, the thickness of the whole apparatus will become thick, and the accuracy which stands upright will also be a subject. A magnetic element using a Hall element is also known as the magnetic sensor 112. The Hall element is a magnetic sensor element that detects a magnetic field intensity having a component perpendicular to the magnetic sensitive surface. Therefore, similarly to the rotation detection device 101 of the conventional example, the magnetic field strength acting on the Hall element changes due to the variation in the gap between the Hall element and the gear-like magnetic body, so that the rotation cannot be detected with high accuracy.

  As shown in FIG. 16, in the rotation detection device 101 of the conventional example, the magnet 133 is disposed on the upper surface side of the convex portion 162 and the concave portion 163, and the magnetic sensor 112 is disposed on the lower surface side. Furthermore, it is necessary to ensure the positional accuracy of installing the magnetic sensor 112 and the magnet 133 in order to prevent a decrease in detection accuracy. Therefore, the magnet 133 and the magnetic sensor element 112 are housed inside the housing 110 using the housing 110 that sandwiches the convex portion 162 and the concave portion 163 in the vertical direction. In this case, the thickness in the height direction increases and a small sensor cannot be manufactured.

  As described above, in the rotation detection device 101 of the conventional example, there is a problem that it is difficult to easily install the magnetic sensor 112 and the magnet 133 because the restrictions when installing the magnetic sensor 112 and the magnet 133 are large. Further, using the casing 110 formed over the upper and lower surfaces of the gear-like magnetic body 161 is contrary to the size reduction of the rotation detecting device 101.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a rotation detection device that can easily install a magnetic sensor and a magnet and can accurately detect the rotation of a gear-like magnetic body. .

  The rotation detection device of the present invention has an upper surface, a lower surface, an outer peripheral side surface connecting between the outer peripheral edge portions of the upper surface and the lower surface, and an uneven portion provided continuously in the rotation direction of the outer peripheral side surface, The concavo-convex portion is a rotation detecting device that detects rotation of a gear-like magnetic body including a plurality of convex portions projecting outward from the outer peripheral side surface and a concave portion between the plurality of convex portions. A magnet disposed on the upper surface side or the lower surface side of a portion with a gap between the uneven portion and a magnetic sensor disposed between the magnet and the uneven portion, The magnetic sensor includes two magnetic sensor elements and a soft magnetic material, and each of the two magnetic sensor elements has a fixed magnetic layer whose magnetization is fixed and a free magnetic layer whose magnetization is changed by an external magnetic field. The magnetization of the free magnetic layer is saturated by the magnet. The magnetization directions of the pinned magnetic layers of the two magnetic sensor elements are oriented in the same direction substantially parallel to the upper surface or the lower surface, and the direction from the lower surface toward the upper surface is the height direction. The soft magnetic body is provided between the two magnetic sensor elements and protrudes in the height direction from the two magnetic sensor elements. A bridge circuit is configured.

  According to this, the direction of the magnetic field acting on the magnetic sensor changes between when the convex portion faces the magnetic sensor according to the rotation of the gear-shaped magnetic body and when the concave portion faces, and the convex portion When facing each other, the magnetic field components collected at the convex portions act in the height direction of the magnetic sensor. Since the magnetic path for converting the magnetic field component in the height direction into the in-plane direction is formed by the soft magnetic material and the magnetic sensor element, the magnetic field component in the height direction is in the in-plane direction of the two magnetic sensor elements. The direction of the magnetic field can be detected by branching to each.

  Therefore, it is not necessary to install a magnetic sensor vertically to detect the magnetic field component in the height direction, and the magnetic sensor is installed so that the magnetization direction of the pinned magnetic layer is substantially parallel to the upper or lower surface of the gear-like magnetic body. can do. Moreover, since the magnet and the magnetic sensor are provided on either the upper surface side or the lower surface side of the gear-like magnetic body, the magnet and the magnetic sensor can be easily arranged without using a specially-shaped housing. .

  Furthermore, since the magnet is provided so that the magnetic flux generated from the magnets saturates the magnetization of the free magnetic layers of the two magnetic sensor elements, the magnetization of the free magnetic layer does not depend on the magnetic field strength and acts on the magnetic sensor element. Depends only on the direction. Therefore, even when the gap between the magnetic sensor and the gear-shaped magnetic body fluctuates or when the distance between the magnetic sensor and the magnet is shifted, the magnetic field strength changes, but the magnetic field acting on the two magnetic sensor elements changes. Since the change in direction is small, the occurrence of an error when detecting the concavo-convex portion is suppressed, and rotation can be detected with high accuracy.

  According to the rotation detection device of the present invention, the magnetic sensor and the magnet can be easily installed, and the rotation of the gear-like magnetic body can be detected with high accuracy.

  The two magnetic sensor elements and the soft magnetic body extend in the first direction when the directions orthogonal to each other in the plane substantially parallel to the upper surface or the lower surface are defined as a first direction and a second direction. The magnetization directions of the pinned magnetic layers of the two magnetic sensor elements are both directed to the second direction, and the first direction matches the rotational direction of the outer peripheral side surface. Is preferred. According to this, since the bridge circuit is configured by the magnetic sensor element and the magnetization direction of the fixed magnetic layer is the same, even if the magnetic sensor is displaced in the second direction with respect to the magnet, The occurrence of detection errors can be suppressed by canceling out the second direction component of the magnetic field generated from the magnet.

  In the first direction, the magnetic sensor is preferably arranged so as to be shifted with respect to the magnet. According to this, when the concave portion faces the magnetic sensor, the magnetic field generated from the magnet acts in the first direction of the magnetic sensor and the magnetic field in the height direction does not act. Can do.

  It is preferable that the magnetic sensor is disposed on one surface of the front and back surfaces of the substrate, and the magnet is disposed on the other surface. According to this, it becomes possible to reduce the size of the rotation detection device, and the magnet and the magnetic sensor can be easily aligned and installed facing the concavo-convex portion.

  The soft magnetic body has end portions facing each other in the height direction, and the end portions located on the two magnetic sensor element sides are arranged to overlap a part of the two magnetic sensor elements. It is preferable. According to this, when the convex part faces the magnetic sensor, the magnetic field component in the height direction acting on the magnetic sensor is converged on the soft magnetic body, and a part of the magnetic sensor element and the soft magnetic body overlap. The magnetic path is converted through the portion in the second direction of the magnetic sensor element. Therefore, since the magnetic field component in the height direction can be reliably converted to the second direction, the uneven portion can be detected reliably.

  It is preferable that the center of the magnetic sensor element in the width direction is located outside the soft magnetic body. According to this, the magnetic field component in the height direction can be reliably converted into the second direction.

  Furthermore, it is preferable to have two magnetic sensor elements and to form a full bridge circuit with the four magnetic sensor elements. According to this, a differential output can be obtained by the resistance change of the magnetic sensor element, and the uneven portion can be detected with high accuracy.

  A rotation reference part is provided in a part of the plurality of uneven parts provided in the gear-like magnetic body, and the rotation reference part has a width different from that of the protrusion and the recess. Or it is preferable that the rotation reference | standard recessed part is provided. According to this, it becomes easy to define the origin of rotation and the direction of rotation can be known.

  According to the rotation detection device of the present invention, the magnetic sensor and the magnet can be easily installed, and the rotation of the gear-like magnetic body can be detected with high accuracy.

It is a partial expansion perspective view of the rotation detector in the 1st embodiment of the present invention. It is a top view of a gear-like magnetic body. It is the (a) partial expansion front view and (b) partial expansion side view of the rotation detection apparatus of this embodiment. It is a top view of the magnetic sensor in this embodiment. It is sectional drawing of a magnetic sensor when it cut | disconnects by the VV line | wire of FIG. 4, and it sees from the arrow direction. It is a typical partial expanded sectional view of the magnetic sensor element which comprises the magnetic sensor in this embodiment. It is a partial expanded front view of a rotation detection device for explaining a detection method of a concave part of a gear-like magnetic body. It is a top view of the magnetic sensor for demonstrating the detection method of the recessed part of a gear-shaped magnetic body. It is a full bridge circuit composed of four magnetic sensor elements. It is a partial enlarged front view of a rotation detecting device for explaining a method for detecting a convex portion of a gear-like magnetic body. It is (a) a top view of a magnetic sensor and (b) a partial expanded sectional view for explaining a detecting method of a convex part of a gear-like magnetic body. It is a full bridge circuit composed of four magnetic sensor elements. (A) A partially enlarged plan view of the rotation detection device, and (b) for explaining a method of detecting the concave portion of the gear-like magnetic body when the magnetic sensor is displaced in the rotation detection device of the present embodiment. It is a top view of a magnetic sensor. (A) Partially enlarged plan view of the rotation detection device, and (b) for explaining a method of detecting the convex portion of the gear-like magnetic body when the magnetic sensor is displaced in the rotation detection device of the present embodiment. FIG. 3 is a plan view of a magnetic sensor. It is (a) front view and (b) side view of the rotation detection apparatus in 2nd Embodiment. It is a partial expansion perspective view of the rotation detection apparatus of a prior art example.

  Hereinafter, a rotation detection device according to a specific embodiment of the present invention will be described with reference to the drawings. In addition, the dimension of each drawing is changed and shown suitably.

  FIG. 1 is a partially enlarged perspective view of the rotation detection device of the first embodiment. FIG. 2 is a plan view of the gear-like magnetic body. FIG. 3A is a front view of the rotation detection device of the present embodiment, and FIG. 3B is a side view of the rotation detection device.

  As shown in FIG. 1, the rotation detection device 10 of this embodiment includes a gear-shaped magnetic body 61, a magnet 33, and a magnetic sensor 12.

  The gear-like magnetic body 61 shown in FIGS. 1 and 2 has a ring-shaped portion 67 and a plurality of convex portions 62 that protrude outward from the ring-shaped portion 67. As shown in FIG. 1, the ring-shaped portion 67 has an upper surface 67a, a lower surface 67b, and an outer peripheral side surface 67c that connects the outer peripheral edge portions of the upper surface 67a and the lower surface 67b. The convex portion 62 is provided on the outer peripheral side surface 67 c and protrudes in the radial direction D1 of the gear-like magnetic body 61.

  As shown in FIG. 2, the center of the gear-like magnetic body 61 is the rotation center O, and the gear-like magnetic body 61 can rotate clockwise (CW) and counterclockwise (CCW) with the rotation center O as the rotation axis. It is supported.

  The plurality of convex portions 62 are arranged at intervals in the rotation directions CW and CCW, and a concave portion 63 is provided between the adjacent convex portions 62. The plurality of convex portions 62 and the plurality of concave portions 63 are each provided with a constant width. Thus, the uneven part 64 in which the convex part 62 and the concave part 63 are arranged alternately and continuously in the rotation directions CW and CCW is provided. Moreover, the width dimension T1 of the wide convex part 62a which is a part of the convex part 62 is formed wider than the other convex parts 62, and the width dimension of the wide concave parts 63a and 63b adjacent to the wide convex part 62a. T2 and T3 are formed wider than the other recesses 63. In addition, the width dimension T2 of the wide recessed part 63a and the width dimension T3 of the wide recessed part 63b are formed in different sizes.

  Since the wide convex portion 62a and the wide concave portions 63a and 63b are formed with different width dimensions from the other convex portions 62 and concave portions 63, the wide convex portion 62a and the wide concave portions 63a and 63b are detected as the rotation reference portion 65. As a result, the origin of rotation of the gear-like magnetic body 61 can be easily defined, and the rotation direction can be known.

  As shown in FIG. 1, the magnet 33 is disposed on the lower surface 67 b side of the gear-like magnetic body 61 with a space between the uneven portion 64 and the magnetic sensor 12 is disposed between the magnet 33 and the uneven portion 64. ing. In the present embodiment, the magnet 33 is magnetized in the vertical direction. For example, the lower surface side (the surface in the Z2 direction) of the magnet 33 is magnetized to the N pole, and the upper surface side (the surface in the Z1 direction) is magnetized to the S pole. It is magnetized. The gear-like magnetic body 61 is made of, for example, an Fe-based soft magnetic body.

  FIG. 3A is a partially enlarged front view of the rotation detection device 10 of the present embodiment when viewed from the Y2 direction in FIG. 1 toward the Y1 direction, and FIG. 3B is X1 in FIG. It is a partial enlarged side view when it sees toward X2 direction from a direction.

  As shown in FIGS. 3A and 3B, the magnet 33 and the magnetic sensor 12 are provided on the same substrate 15, and the magnet 33 is disposed on the lower surface of the substrate 15 and the magnetic sensor 12. Is disposed on the upper surface of the substrate 15. 3A and 3B, in the height direction (Z1-Z2 direction), the magnetic sensor 12 is arranged with a concavo-convex portion 64 and a gap, and with respect to the magnet 33. Arranged with a gap. Further, as shown in FIG. 3A, the magnetic sensor 12 is arranged so as to be shifted from the magnet 33 in the X1-X2 direction. Note that, as shown in FIG. 3B, the magnetic sensor 12 is disposed at a position overlapping the magnet 33 in the Y1-Y2 direction.

  In the present embodiment, by providing the magnet 33 and the magnetic sensor 12 on the same substrate 15, the rotation detecting device 10 can be reduced in size, and the magnet 33 and the magnetic sensor 12 can be easily positioned facing the uneven portion 64. Can be installed together. Further, when the magnet 33 and the magnetic sensor 12 are separately arranged on the upper and lower surfaces of the gear-like magnetic body 61 as in the conventional rotation detection device 101, or the magnet 33 and the magnetic sensor 12 are mounted on different substrates. Compared with the case where it does, it is easy to control the distance of the magnet 33 and the magnetic sensor 12, and to arrange | position the magnet 33 and the magnetic sensor 12. FIG.

  The magnetic sensor 12 is a magnetic switch that generates an on / off signal according to the direction of the magnetic field. The direction of the magnetic field acting on the magnetic sensor 12 changes depending on whether the convex portion 62 is positioned facing the magnetic sensor 12 or the concave portion 63 is positioned, thereby rotating and rotating the gear-shaped magnetic body 61. Can be detected.

  FIG. 4 is a plan view of the magnetic sensor in the present embodiment. FIG. 5 is a cross-sectional view of the magnetic sensor as viewed from the direction of the arrow cut along the line VV in FIG. As shown in FIGS. 4 and 5, the magnetic sensor 12 in the present embodiment includes a magnetic sensor element group 21 including a plurality of magnetic sensor elements 21 a to 21 d and a soft magnetic body 31. In the present embodiment, four magnetic sensor elements 21a to 21d are shown. However, the present invention is not limited to this, and detection is possible with at least two magnetic sensor elements, or more magnetic sensor elements are provided. Is also possible.

  As shown in FIG. 4, the plurality of magnetic sensor elements 21a to 21d extend in the X1-X2 direction, and are spaced from each other in the Y1-Y2 direction. The soft magnetic bodies 31 extend in the X1-X2 direction and are spaced from each other in the Y1-Y2 direction, like the magnetic sensor elements 21a to 21d. Connection portions 32 are connected to both ends of the soft magnetic body 31 in the X1-X2 direction, and the connection portion 32 connects the plurality of soft magnetic bodies 31 to each other in the Y1-Y2 direction.

  As shown in FIG. 4, the soft magnetic body 31 is between the two magnetic sensor elements 21a and 21b and between the two magnetic sensor elements 21c and 21d in the Y1-Y2 direction. Each is provided.

  As shown in FIG. 5, the magnetic sensor element group 21 is provided on the substrate 30. The soft magnetic body 31 and the connecting portion 32 are provided on the magnetic sensor element group 21, and the soft magnetic body 31 is disposed so as to overlap each part of the magnetic sensor elements 21a to 21d. As shown in FIG. 5, the soft magnetic body 31 is provided between the magnetic sensor elements 21a to 21d in the Y1-Y2 direction, and protrudes in the height direction (Z1 direction) from the magnetic sensor elements 21a to 21d. Provided.

  In this embodiment, the soft magnetic body 31 and the connection part 32 are integrally formed using the same material. The soft magnetic body 31 and the connection portion 32 are formed of a soft magnetic material containing at least one material selected from soft magnetic materials such as NiFe, CoFe, CoFeSiB, CoZrTi, and CoZrNb.

  FIG. 6 is a schematic partial enlarged cross-sectional view showing the laminated structure of the magnetic sensor element as viewed from the direction of the arrow cut along the line VV in FIG. In this embodiment, giant magnetoresistive (GMR (Giant Magneto Resistance)) elements are used as the magnetic sensor elements 21a to 21d. FIG. 6 shows a laminated structure of the magnetoresistive film 43 constituting the magnetic sensor element 21a for one magnetic sensor element (for example, 21a) among the plurality of magnetic sensor elements 21a to 21d.

  The magnetoresistive film 43 is formed on the upper surface of the silicon substrate 41 with the insulating film 42 and the seed layer 49 interposed therebetween. As shown in FIG. 4, the magnetoresistive film 43 is formed by laminating an antiferromagnetic layer 44, a pinned magnetic layer 45, a nonmagnetic layer 46, and a free magnetic layer 47 in this order, and the surface of the free magnetic layer 47 is protected. It is configured to be covered with a layer 48.

  In the magnetoresistive effect film 43, the magnetization direction 45 a of the pinned magnetic layer 45 is fixed by exchange coupling between the antiferromagnetic layer 44 and the pinned magnetic layer 45. As shown in FIG. 6, the magnetization direction 45 a faces the Y1 direction in a state parallel to the silicon substrate 41. Further, the magnetization direction 47a of the free magnetic layer 47 changes depending on the magnetic field applied from the outside. In the following description, “the magnetization direction 45a of the pinned magnetic layer 45” is represented as “the pinned magnetization direction 45a”. The “magnetization direction 47a of the free magnetic layer 47” is expressed as “free magnetization direction 47a”.

  In the present embodiment, the insulating film 42 may be a silicon oxide film obtained by thermally oxidizing the silicon substrate 41, an alumina film formed by sputtering or the like, an oxide film, or the like. The antiferromagnetic layer 44 is made of an antiferromagnetic material such as an Ir—Mn alloy (iridium-manganese alloy). The pinned magnetic layer 45 is made of a soft magnetic material such as a Co—Fe alloy (cobalt-iron alloy). The nonmagnetic layer 46 is made of Cu (copper) or the like. The free magnetic layer 47 is made of a soft magnetic material such as a Ni—Fe alloy (nickel-iron alloy) having a small coercive force and a large magnetic permeability. The protective layer 48 is a layer such as Ta (tantalum). The seed layer 49 is made of NiFeCr. With this layer, the crystal orientation of the antiferromagnetic layer 44 thereon is adjusted to (111). Note that the laminated structure of the magnetoresistive film 43 shown in FIG. 6 and the materials used are examples, and other laminated structures may be used. The antiferromagnetic layer 44 may be omitted, and the pinned magnetic layer 45 may be of a so-called self-pin type structure including a first ferromagnetic layer / nonmagnetic coupling layer / second ferromagnetic layer. In this case, the first ferromagnetic layer is in direct contact with the seed layer 49. Further, the second ferromagnetic layer is in direct contact with the nonmagnetic layer 46. The nonmagnetic coupling layer uses conductive Ru or the like. The magnetizations of the first ferromagnetic layer and the second ferromagnetic layer are directed in directions different by 180 ° due to indirect exchange interaction (RKKY-like interaction) due to conductive electrons.

  As shown in FIG. 4, the fixed magnetization directions 45a of the magnetic sensor elements 21a to 21d are all fixed in the Y1 direction and directed in the same direction. Moreover, the free magnetization direction 47a changes with the magnetic field applied from the outside. For example, in a state where the magnet 33, the gear-like magnetic body 61, etc. are not arranged and no external magnetic field is applied, the free magnetization direction 47a is oriented in the X1-X2 direction due to the shape anisotropy of the magnetic sensor elements 21a to 21d and fixed. The magnetization direction 45a and the free magnetization direction 47a are orthogonal to each other. In the present embodiment, the fixed magnetization direction 45a and the free magnetization direction 47a are provided in the in-plane direction of the magnetoresistive effect film 43, and the magnetic sensor 12 detects a magnetic field component in the film plane.

  As shown in FIG. 4, the angle formed by the free magnetization direction 47a and the fixed magnetization direction 45a is θ. When a magnetic field is applied to the magnetic sensor elements 21a to 21d and the free magnetization direction 47a approaches parallel to the fixed magnetization direction 45a, the angle θ decreases and the electrical resistance decreases. On the other hand, when the free magnetization direction 47a approaches antiparallel to the fixed magnetization direction 45a, the angle θ increases and the electrical resistance value increases.

  In the present embodiment, the residual magnetic flux density of the magnet 33 is set sufficiently high, and the magnetization of the free magnetic layer 47 of the magnetic sensor elements 21 a to 21 d is saturated by the magnet 33. In other words, the free magnetization direction 47 a changes depending on only the direction of the magnetic field 34 of the magnet 33 without depending on the magnetic field strength of the magnet 33. Therefore, in this embodiment, the magnet 33 having a large residual magnetic flux density such as a neodymium magnet, a samarium cobalt magnet, an alnico magnet, a ferrite magnet, or a plastic magnet is suitable. As the magnet 33, for example, a magnet having a residual magnetic flux density of 100 to 1500 mT is selected.

  In the rotation detection device 10 of the present embodiment, the direction of the magnetic field acting on the magnetic sensor 12 changes as the gear-like magnetic body 61 rotates, and the resistances of the magnetic sensor elements 21a to 21d change. Based on this resistance change, the rotation of the gear-shaped magnetic body 61 can be detected.

  FIG. 7 is a partially enlarged front view of the rotation detecting device for explaining a method of detecting the concave portion of the gear-like magnetic body. FIG. 8 is a plan view of a magnetic sensor for explaining a method of detecting a recess in the gear-like magnetic body. FIG. 9 shows a full bridge circuit composed of four magnetic sensor elements.

  As shown in FIG. 7, when the concave portion 63 is positioned upward (Z1 direction) facing the magnetic sensor 12, the magnetic sensor 12 is arranged to be shifted in the X1-X2 direction with respect to the magnet 33. A magnetic field 34 generated from the magnet 33 acts on the magnetic sensor 12 in the X1-X2 direction. Moreover, since the convex part 62 is separated from the magnet 33, the magnetic field 34 generated from the magnet 33 is suppressed from concentrating on the convex part 62 of the gear-like magnetic body 61, and the magnetic sensor 12 has a magnetic field in the Z1-Z2 direction. The ingredient has little effect.

  Therefore, as shown in FIG. 8, the x component 34 a of the magnetic field 34 generated from the magnet 33 acts on the magnetic sensor 12. As shown in FIG. 8, the x component 34a acts on the magnetic sensor elements 21a to 21d in the same direction (X1 direction), and each free magnetization direction 47a is X1 along the direction of the x component 34a. Directed in the direction. That is, the free magnetization direction 47a is oriented in a direction orthogonal to the fixed magnetization direction 45a. Therefore, in the magnetic sensor elements 21a to 21d, the angle θ between the fixed magnetization direction 45a and the free magnetization direction 47a is the same, and the resistance values of the magnetic sensor elements 21a to 21d are substantially equal.

As shown in FIG. 9, four magnetic sensor elements 21 a to 21 d are electrically connected to form a full bridge circuit 53. As shown in FIG. 9, the magnetic sensor element 21a and the magnetic sensor element 21b connected in series between the input terminal (V _dd ) and the ground terminal (GND), and the magnetic sensor element 21c and the magnetic sensor connected in series are connected. Elements 21d are connected in parallel to form a full bridge circuit 53. Series-connected magnetic sensor element 21a and the midpoint voltage from between the magnetic sensor element 21b (V ₁₎ is taken out, also the magnetic sensor element 21c and the midpoint voltage from between the magnetic sensor element 21d (V ₂₎ is It is taken out. The difference between the midpoint voltage _{(V 1)} and the midpoint voltage _{(V 2) (V 1 -V} 2) is output as amplified output voltage _{(V out)} by the differential amplifier 54.

As shown in FIG. 7, when the concave portion 63 is located above the magnetic sensor 12, the resistance values of the magnetic sensor elements 21 a to 21 d are substantially the same, so the midpoint voltage (V ₁ ) shown in FIG. 9. And the midpoint voltage (V ₂ ) have the same value, and the difference (V ₁ −V ₂ ) is 0V. As described above, the recess 63 can be detected in the rotation detection device 10 of the present embodiment.

  In the magnetic sensor 12 of the present embodiment, the magnetization of the free magnetic layer 47 is saturated by the magnet 33, and the resistance values of the magnetic sensor elements 21a to 21d vary depending on the magnetic field direction without depending on the magnetic field strength. For example, when installing the gear-shaped magnetic body 61, the magnetic sensor 12, and the magnet 33, the height direction (Z direction) distance between the magnetic sensor 12 and the magnet 33, or the height between the magnetic sensor 12 and the concave and convex portion 64. Variations in distance in the vertical direction (Z direction) may occur. Even in this case, although the intensity of the magnetic field 34 acting on the magnetic sensor 12 changes, the change in the direction of the magnetic field 34 is small, so that the change in the output of the magnetic sensor 12 is suppressed. Therefore, the concave portion 63 can be detected with high accuracy. In addition, since there are few restrictions on the distance in the height direction (Z direction) between the magnetic sensor 12 and the magnet 33 and the distance in the height direction (Z direction) between the magnetic sensor 12 and the concavo-convex portion 64, the magnetic sensor 12 and the magnet 33. Can be easily installed.

  FIG. 10 is a partially enlarged front view of the rotation detecting device for explaining a method of detecting the convex portion of the gear-like magnetic body. FIG. 11A is a plan view of a magnetic sensor for explaining a method of detecting a convex portion of the gear-like magnetic body, and FIG. 11B is a partial enlarged cross-sectional view of the magnetic sensor. FIG. 12 shows a full bridge circuit composed of four magnetic sensor elements.

  As shown in FIG. 10, when the convex portion 62 is positioned upward (Z1 direction) facing the magnetic sensor 12, the magnetic field 34 generated from the magnet 33 is convex on the gear-shaped magnetic body 61 upward (Z1 direction). Concentrating on the part 62, the direction of the magnetic field 34 is bent. Since the magnetic sensor 12 is arranged so as to be shifted in the X1-X2 direction with respect to the magnet 33, the magnetic field 34 generated from the magnet 33 and bent in the direction of the convex portion 62 is inclined with respect to the magnetic sensor 12. The magnetic field component in the X1-X2 direction and the magnetic field component in the Z1-Z2 direction act on the magnetic sensor 12.

  As shown in FIG. 11A, the x component 34a of the magnetic field 34 generated from the magnet 33 acts on the magnetic sensor elements 21a to 21d in the same direction (X1 direction). As shown in FIG. 11B, regarding the two magnetic sensor elements 21a and 21b, the soft magnetic body 31 is provided on the two magnetic sensor elements 21a and 21b in the Z1-Z2 direction. It has been. That is, the soft magnetic body 31 is provided between the two magnetic sensor elements 21a and 21b and the concavo-convex portion 64 (not shown in FIG. 8B). The soft magnetic body 31 is provided between the two magnetic sensor elements 21a and 21b in the Y1-Y2 direction, and the end 31a located on the two magnetic sensor elements 21a and 21b side has 2 The two magnetic sensor elements 21a and 21b are arranged so as to overlap each part. As shown in FIG. 11B, the soft magnetic body 31 is similarly provided for the two magnetic sensor elements 21c and 21d.

Thereby, a magnetic path that bends from the Z1-Z2 direction to the Y2 direction is formed by the soft magnetic body 31 and the magnetic sensor element 21a, and a magnetic path that curves from the Z1-Z2 direction to the Y1 direction is formed by the soft magnetic body 31 and the magnetic sensor element 21b. A path is formed. Therefore, the magnetic flux of the z component 34c of the magnetic field 34 is converged on the soft magnetic body 31 and flows out to the end 31a of the soft magnetic body 31 on the magnetic sensor elements 21a and 21b side. The magnetic flux of the z component 34c of the magnetic field 34 is converted into magnetic field components in the Y1 direction and the Y2 direction along the width direction of the magnetic sensor element 21a and the magnetic sensor element 21b. Thus, the z component 34c of the magnetic field 34 generated from the magnet 33 acts in the Y2 direction of the magnetic sensor element 21a and acts in the Y1 direction of the magnetic sensor element 21b. Similarly, for the magnetic sensor elements 21c and 21d, the z component 34c of the magnetic field 34 acts in the Y2 direction of the magnetic sensor element 21c and acts in the Y1 direction of the magnetic sensor element 21d.

  Accordingly, as shown in FIG. 11A, the x component 34a of the magnetic field 34 acts in the X1 direction of the magnetic sensor element 21a, and the z component 34c of the magnetic field 34 is changed in magnetic path by the soft magnetic body 31, so that the magnetic sensor It acts in the Y2 direction of the element 21a. The free magnetization direction 47a is directed along the direction of the magnetic field 35 obtained by superimposing the two magnetic field components, and the angle between the fixed magnetization direction 45a and the free magnetization direction 47a changes. Since the z component 34c of the magnetic field 34 is applied to the magnetic sensor element 21b in the Y1 direction, the magnetic sensor element 21b is free so that the angle between the fixed magnetization direction 45a and the free magnetization direction 47a becomes smaller, contrary to the magnetic sensor element 21a. The magnetization direction 47a changes. Similarly to the magnetic sensor element 21a, the magnetic field 34 from the magnet 33 acts on the magnetic sensor element 21c, and the magnetic field 34 from the magnet 33 acts on the magnetic sensor element 21d similarly to the magnetic sensor element 21b.

FIG. 12 shows the full bridge circuit 53 when the convex portion 62 is detected. The resistance values of the magnetic sensor element 21a and the magnetic sensor element 21c are larger than the output of the full bridge circuit 53 when detecting the recess 63 shown in FIG. 9, and the resistance values of the magnetic sensor element 21b and the magnetic sensor element 21d are increased. Becomes smaller. Therefore, the midpoint voltage (V ₁ ) between the magnetic sensor element 21a and the magnetic sensor element 21b decreases, and the midpoint voltage (V ₂ ) between the magnetic sensor element 21c and the magnetic sensor element 21d increases. Then, the difference (V ₁ −V ₂ ) between the midpoint voltages is amplified by the differential amplifier 54, and the output voltage (V _out ) is output. The convex portion 62 can be detected with high accuracy by this output voltage (V _out ).

  Moreover, in the rotation detection apparatus 10 of this embodiment, as shown in FIG.11 (b), in the center position 23 (FIG.8 (b)) of each width direction (Y1-Y2 direction) of the magnetic sensor elements 21a and 21b. (Shown by a two-dot chain line 23) is located outside the soft magnetic body 31. By doing so, the length of the magnetic sensor element 21b extending in the Y2 direction and the magnetic sensor element 21b extending in the Y1 direction can be made longer than the side surface 31b of the soft magnetic body 31, and therefore, the z component 34c of the magnetic field 34 generated from the magnet 33. Is reliably converted in the Y1-Y2 direction.

  In this embodiment, the width dimension (dimension in the Y1-Y2 direction) of the magnetic sensor elements 21a and 21b is about 5 μm to 15 μm, the width dimension of the soft magnetic body 31 is 10 μm to 20 μm, and the height dimension of the soft magnetic body 31 is 10 μm. It can be formed to about 30 μm. The center position 23 in the width direction of the magnetic sensor elements 21 a and 21 b is located 0.5 μm or more outside the side surface 31 b of the soft magnetic body 31. As shown in FIG. 11B, the cross-sectional shape of the soft magnetic body 31 is rectangular, and in order to efficiently converge the z component 34c of the magnetic field 34 from the magnet 33, the width dimension of the soft magnetic body 31 is larger. However, it is preferable to increase the height dimension.

  As described above, the direction of the magnetic field 34 acting on the magnetic sensor 12 changes between when the convex portion 62 faces the magnetic sensor 12 and when the concave portion 63 faces, and the convex portion 62 faces the magnetic sensor 12. Sometimes, in addition to the magnetic field component in the in-plane direction of the magnetic sensor 12, the magnetic field component collected at the convex portion 62 acts in the height direction of the magnetic sensor 12. Since the magnetic path for converting the magnetic field component in the height direction into the in-plane direction is formed by the soft magnetic body 31 and the magnetic sensor elements 21a to 21d, the magnetic field component in the height direction has two magnetic sensor elements 21a. The direction of the magnetic field 34 can be detected by branching in the in-plane direction of ˜21d.

  Therefore, it is not necessary to provide the magnetic sensor 12 vertically in order to detect the magnetic field component in the height direction, and the magnetization direction 45a of the pinned magnetic layer 45 is substantially parallel to the upper surface 67a or the lower surface 67b of the gear-like magnetic body 61. Thus, the magnetic sensor 12 can be installed. Further, since the magnet 33 and the magnetic sensor 12 are provided on either the upper surface 67a side or the lower surface 67b side of the gear-like magnetic body 61, a special shape used in the conventional rotation detection device 101 shown in FIG. The magnet 33 and the magnetic sensor 12 can be easily arranged without using the casing 110.

  Furthermore, since the magnet 33 is provided so that the magnetic flux generated from the magnet 33 saturates the magnetization of the free magnetic layer 47 of the two magnetic sensor elements 21a to 21d, the magnetization of the free magnetic layer 47 does not depend on the magnetic field strength. It depends only on the direction of the magnetic field acting on the magnetic sensor elements 21a to 21d. Therefore, even when the gap between the magnetic sensor 12 and the gear-like magnetic body 61 fluctuates or when the relative positional relationship between the magnetic sensor 12 and the magnet 33 deviates, the magnetic field strength changes, but the two magnetic sensors. Since the change in the direction of the magnetic field acting on the elements 21a to 21d is small, the occurrence of an error when detecting the uneven portion 64 is suppressed, and the rotation can be detected with high accuracy.

  Therefore, according to the rotation detection device 10 of the present embodiment, the magnetic sensor 12 and the magnet 33 can be easily installed, and the rotation of the gear-like magnetic body 61 can be detected with high accuracy.

  7 to 12 show the case where the x component 34a or the z component 34c of the magnetic field 34 acts on the magnetic sensor 12, but according to the rotation detection device 10 of the present embodiment. Even when the y component 34b acts, it is possible to detect with high accuracy while suppressing the occurrence of errors. FIG. 13A is a partially enlarged plan view of the rotation detection device for explaining a method of detecting the concave portion of the gear-like magnetic body when the magnetic sensor is displaced in the rotation detection device of the present embodiment. FIG. 13B is a plan view of the magnetic sensor.

  As shown in FIG. 13A, when the magnetic sensor 12 is arranged so as to be shifted in the Y1 direction, when the concave portion 63 faces the magnetic sensor 12, the magnetic field 34 from the magnet 33 is viewed in plan with respect to the magnetic sensor 12. Acts diagonally. That is, the x component 34a and the y component 34b of the magnetic field 34 act on the magnetic sensor 12, and the z component 34c of the magnetic field 34 does not act.

  As shown in FIG. 13B, the y component 34b of the magnetic field 34 acts on the magnetic sensor elements 21a to 21d in the same direction (Y2 direction) and with the same magnitude. Accordingly, the free magnetization directions 47a of the magnetic sensor elements 21a to 21d are all rotated in the same direction and are directed in the direction in which the angle θ is increased. Therefore, even when the y component 34b acts on each of the magnetic sensor elements 21a to 21d, all show the same resistance change, so that the midpoint potentials (V1, V2) of the full bridge circuit 53 shown in FIG. Almost no change. Therefore, the occurrence of an error due to the y component 34b is suppressed, and the recess 63 can be detected with high accuracy.

  FIG. 14A is a partially enlarged plan view of the rotation detection device for explaining a method of detecting the convex portion of the gear-like magnetic body when the magnetic sensor is displaced in the rotation detection device of the present embodiment. FIG. 14B is a plan view of the magnetic sensor.

  As shown in FIG. 14A, when the magnetic sensor 12 is arranged so as to be shifted in the Y1 direction and the convex portion 62 faces the magnetic sensor 12, the x component 34 a and the y component 34 b of the magnetic field 34 are changed to the magnetic sensor 12. 10 and the z component 34c of the magnetic field 34 acts on the magnetic sensor 12 as in FIG.

  The z component 34c of the magnetic field 34 is converted into a magnetic field in the Y1 direction and the Y2 direction by the soft magnetic body 31, as in FIG. Therefore, as shown in FIG. 14B, the z component 34c of the magnetic field 34 acts on the magnetic sensor element 21a in the Y2 direction and acts on the magnetic sensor element 21b in the opposite Y1 direction. A magnetic field 35 obtained by combining the magnetic field components 34 a to 34 c acts on the magnetic sensor elements 21 a and 21 b, and the free magnetization direction 47 a is directed in a direction along the combined magnetic field 35. As shown in FIG. 14B, the free magnetization direction 47a changes in the direction in which the resistance increases in the magnetic sensor element 21a, and the free magnetization direction 47a changes in the direction in which the resistance decreases in the magnetic sensor element 21b. Similarly, in the magnetic sensor elements 21c and 21d, the free magnetization direction 47a changes in the direction in which the resistance of the magnetic sensor element 21c increases, and the free magnetization direction 47a changes in the direction in which the resistance of the magnetic sensor element 21d decreases. Thereby, the differential output from the full bridge circuit 53 is obtained, and the convex portion 62 can be detected with high accuracy.

  As described above, even if the magnetic field 34 in the Y direction acts on the magnetic sensor 12, the y component 34b of the magnetic field 34 acts on the magnetic sensor elements 21a to 21d in the same direction. Therefore, since the resistance values of the magnetic sensor elements 21a to 21d due to the y component 34b change in the same manner, the error due to the y component 34b of the magnetic field 34 is canceled by the full bridge circuit 53. Therefore, in the rotation detection device 10 of the present embodiment, even when the magnetic sensor 12 is misaligned with respect to the magnet 33, it is possible to detect the concavo-convex portion 64 with high accuracy while suppressing the occurrence of an error.

  FIG. 15 is a (a) front view and (b) side view of a rotation detection device according to the second embodiment. In the rotation detection device 11 of the present embodiment, the relative position of the magnetic sensor 12 and the magnet 33 is the same as that of the first embodiment shown in FIGS. 1 and 3, and the magnetic sensor 12 and the magnet with respect to the gear-like magnetic body 61. The arrangement of 33 is different. As shown in FIG. 15, in the rotation detection device 11 of the present embodiment, the magnetic sensor 12 and the magnet 33 are arranged by being rotated by 90 ° with respect to the gear-like magnetic body 61.

  As shown in FIG. 15A, the rotation detection device 11 of the present embodiment is disposed at a position where the magnetic sensor 12 overlaps the magnet 33 in the X1-X2 direction, and as shown in FIG. The magnetic sensor 12 is arranged to be shifted with respect to the magnet 33 in the Y1-Y2 direction. In the present embodiment, the magnetic sensor elements 21a to 21d and the soft magnetic body 31 constituting the magnetic sensor 12 are also rotated by 90 °, and the magnetic sensor elements 21a to 21d and the soft magnetic body 31 are arranged in the Y1-Y2 direction. It is extended and provided.

  Even in such an arrangement, as in the first embodiment, the direction of the magnetic field 34 acting on the magnetic sensor 12 between the case where the concave portion 63 faces the magnetic sensor 12 and the case where the convex portion 62 faces. Changes, and the convex portion 62 and the concave portion 63 can be detected with high accuracy. In addition, it is not limited to this embodiment, The position of the magnet 33 and the magnetic sensor 12 with respect to the gear-shaped magnetic body 61, a distance, etc. can be changed suitably.

DESCRIPTION OF SYMBOLS 10, 11 Rotation detection apparatus 12 Magnetic sensor 15 Board | substrate 21 Magnetic sensor element group 21a-21d Magnetic sensor element 23 Center position of the width direction of a magnetic sensor element 30 Board | substrate 31 Soft magnetic body 31a End part 32 Connection part 33 Magnet 34 Generated from magnet Magnetic field 34a x component of magnetic field generated from magnet 34b y component of magnetic field generated from magnet 34c z component of magnetic field generated from magnet 35 Magnetic field acting on magnetic sensor element 43 magnetoresistive film 45 fixed magnetic layer 45a fixed magnetization direction (Magnetization direction of pinned magnetic layer)
47 Free magnetic layer 47a Free magnetization direction (magnetization direction of free magnetic layer)
53 Full bridge circuit 61 Gear-like magnetic body 62 Protruding part 62a Wide convex part (rotation reference convex part)
63 recess 63a, 63b wide recess (rotation reference recess)
64 Concavity and convexity 65 Rotation reference part CW, CCW Rotation direction

Claims (8)

An upper surface, a lower surface, an outer peripheral side surface connecting between the outer peripheral edge portions of the upper surface and the lower surface, and an uneven portion provided continuously in a rotation direction of the outer peripheral side surface, the uneven portion from the outer peripheral side surface A rotation detection device that detects rotation of a gear-like magnetic body composed of a plurality of convex portions projecting outward and a concave portion between the plurality of convex portions,
On either the upper surface side or the lower surface side of the concavo-convex portion, the magnet has a magnet disposed with a gap from the concavo-convex portion, and a magnetic sensor disposed between the magnet and the concavo-convex portion. ,
The magnetic sensor includes two magnetic sensor elements and a soft magnetic material,
The two magnetic sensor elements each have a fixed magnetic layer whose magnetization is fixed and a free magnetic layer whose magnetization is changed by an external magnetic field, and the magnetization of the free magnetic layer is saturated by the magnet, The magnetization directions of the fixed magnetic layers of the two magnetic sensor elements are oriented in the same direction substantially parallel to the upper surface or the lower surface,
When the direction from the lower surface toward the upper surface is the height direction, the soft magnetic body is provided between the two magnetic sensor elements and protrudes in the height direction from the two magnetic sensor elements. Provided,
A rotation detection apparatus, wherein a bridge circuit is constituted by the two magnetic sensor elements.   The two magnetic sensor elements and the soft magnetic body extend in the first direction when the directions orthogonal to each other in the plane substantially parallel to the upper surface or the lower surface are defined as a first direction and a second direction. The magnetization directions of the pinned magnetic layers of the two magnetic sensor elements are both directed to the second direction, and the first direction matches the rotational direction of the outer peripheral side surface. The rotation detection device according to claim 1.   The rotation detection device according to claim 2, wherein in the first direction, the magnetic sensor is arranged to be shifted with respect to the magnet.   The rotation detection device according to any one of claims 1 to 3, wherein the magnetic sensor is disposed on one surface of the front and back surfaces of the substrate, and the magnet is disposed on the other surface. . The soft magnetic body has ends facing each other in the height direction,
The said edge part located in the said two magnetic sensor element side is arrange | positioned so that it may overlap with a part of said two magnetic sensor elements, The Claim 1 characterized by the above-mentioned. Rotation detection device.   The rotation detection device according to claim 4, wherein the center of the magnetic sensor element in the width direction is located outside the soft magnetic body.   The rotation detection device according to any one of claims 1 to 6, further comprising two magnetic sensor elements, wherein a full bridge circuit is configured by the four magnetic sensor elements.   A rotation reference part is provided in a part of the plurality of uneven parts provided in the gear-like magnetic body, and the rotation reference part has a width different from that of the protrusion and the recess. Or the rotation reference recessed part is provided, The rotation detection apparatus of any one of Claim 1 to 7 characterized by the above-mentioned.

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