JP2016109472A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the effects on output voltage waveform of the shapes and pitches of irregular parts of a magnetic substance and realize low manufacturing costs in a magnetic sensor for detecting the movement of a magnetic substance.SOLUTION: A magnetic sensor includes GMR elements 22a-22d of magnetic field intensity detection type that are configured the same way and bridge-connected, and a bias magnet 30 for applying a bias magnetic field to the GMR elements 22a-22d, the magnetometric sensor detecting the rotation of a toothed wheel 40 that is a magnetic substance. The GMR elements 22a, 22c and the GMR elements 22b, 22d are arranged within the same plane separately by a prescribed interval. The bias magnet 30 is arranged so that bias magnetic fields facing opposite in directions inclined by a prescribed angle with respect to a direction orthogonal to a line linking the centers of the GMR elements 22a, 22c and MGR elements 22b, 22d within the plane and being equal in intensity are applied to GMR elements 22a, 22c and GMR elements 22b, 22d.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic sensor that detects movement of a magnetic material.

    2. Description of the Related Art Conventionally, a magnetic sensor is known that includes a pair of GMR elements that are identically configured and bridge-connected, and a bias magnet that applies a bias magnetic field to the pair of GMR elements, and detects the movement of a magnetic material. . For example, in Patent Document 1 below, a pair of GMR elements are arranged in the same plane, and a bias magnetic field having the same intensity in a direction parallel to and opposite to a straight line connecting the centers of the pair of GMR elements in the plane. A magnetic sensor in which a bias magnet is arranged so that is applied to a pair of GMR elements is shown. The plane on which the pair of GMR elements are arranged is opposed to the uneven surface of the magnetic body (gear) having unevenness on the outer peripheral surface, and the straight line connecting the centers of the pair of GMR elements is the moving direction of the magnetic body (rotation direction of the gear) The magnetic sensor is arranged so that the voltage waveform corresponding to the resistance change of the GMR element due to the movement of the magnetic material is output from the pair of bridge-connected GMR elements.

  Patent Document 2 listed below includes a pinned phase of a ferromagnetic material whose magnetization direction is fixed in one direction and a free layer of a ferromagnetic material stacked on a pinned layer via a nonmagnetic material through which a current mainly flows. The magnetic sensor which detects the movement of the magnetic body (gear) which has an unevenness | corrugation in an outer peripheral surface is shown using a pair of SV-GMR element which becomes. Also in this magnetic sensor, the pair of SV-GMR elements are bridge-connected, and outputs a voltage corresponding to the resistance change of the SV-GMR element due to the movement of the magnetic material. However, in this magnetic sensor, a pair of SV-GMR elements are arranged in the same plane, and the magnetization direction of each pinned layer of the pair of SV-GMR elements is set within the plane of the pair of SV-GMR elements. The bias magnetic fields having the same intensity are applied to the pair of SV-GMR elements in the same direction perpendicular to the line connecting the centers of the pair of SV-GMR elements, which are orthogonal to the straight line connecting the centers and opposite to each other. A bias magnet is arranged as shown. The plane on which the pair of SV-GMR elements are arranged is opposed to the uneven surface of the magnetic body (gear) having unevenness on the outer peripheral surface, and the straight line connecting the centers of the pair of SV-GMR elements is the moving direction of the magnetic body ( This magnetic sensor is arranged so as to be in a direction orthogonal to the rotation direction of the gear so that a voltage corresponding to a change in resistance of the GMR element due to movement of the magnetic material is output from a pair of bridge-connected GMR elements. ing.

JP-A-9-329462 Japanese Patent Laid-Open No. 2005-233795

  However, in the magnetic sensor described in Patent Document 1, the amplitude of the output voltage waveform varies greatly depending on the shape and pitch of the concavo-convex portions of the magnetic material, and a large distortion occurs in the output voltage waveform (that is, The output voltage waveform deviates significantly from the sine waveform). Therefore, in this magnetic sensor, it is necessary to arrange the GMR element in accordance with the shape and pitch of the uneven portion of the magnetic material, and there is a problem that it is necessary to prepare a magnetic sensor for each magnetic material whose movement is detected. .

In the magnetic sensor described in Patent Document 2, the output voltage is not affected by the pitch of the uneven portions of the magnetic material. However, in order to arrange a pair of SV-GMR elements with different magnetization directions of the pinned layer on the same plane, a pair of SV-GMR elements prepared in advance is on the base (in Patent Document 2, on the bias magnet). Therefore, the manufacturing process of the magnetic sensor becomes complicated and the manufacturing cost of the magnetic sensor increases.

  The present invention has been made in order to cope with such a problem, and an object of the present invention is to reduce the influence on the output voltage waveform due to the shape and pitch of the concave and convex portions of the magnetic material and realize a low manufacturing cost. Is to provide. In addition, in the description of each constituent element of the present invention below, in order to facilitate understanding of the present invention, reference numerals of corresponding portions of the embodiment are described in parentheses, but each constituent element of the present invention is The present invention should not be construed as being limited to the configurations of the corresponding portions indicated by the reference numerals of the embodiments.

  In order to achieve the above-described object, the present invention is characterized in that at least a pair of magnetic field intensity detection type GMR elements (22a, 22b or 22c, 22d) that are identically configured and bridge-connected, and a pair of GMR elements. And a bias magnetic field applying means (30) for applying a bias magnetic field to detect the movement of the magnetic material, wherein a pair of GMR elements are arranged at a predetermined interval in the same plane, and the bias is applied. A magnetic field applying means is applied to the pair of GMR elements in a direction inclined at a predetermined angle with respect to a direction orthogonal to a straight line connecting the centers of the pair of GMR elements in the plane, and having the same strength in the opposite directions. It is in the arrangement.

  In this case, for example, the pair of GMR elements is composed of a linear granular thin film or a linear artificial lattice film formed on the insulating substrate (21), and the insulating substrate is electrically connected to the pair of GMR elements. A plurality of electrodes (23a to 23d) are provided. Further, for example, the pair of GMR elements, the insulating substrate, and the plurality of electrodes are accommodated in a package (10) molded of resin, and a plurality of conductive lead frames (13a to 13a) electrically connected to the plurality of electrodes. 13d) protrudes from the package.

  Further, for example, the bias magnetic field applying means is constituted by a permanent magnet having a rectangular parallelepiped shape and magnetizing the long first surface to the N pole and the second surface opposite to the first surface to the S pole. The permanent magnet has a first surface or a second surface opposed to a pair of GMR elements, and a center line between two long sides of the first surface or the second surface opposed to the pair of GMR elements is a pair of GMR elements. The center of the straight line connecting the centers of the pair of GMR elements is arranged so as to face the point on the center line. Further, for example, the magnetic sensor is applied to detection of movement of a magnetic body having at least one convex portion or concave portion extending in a direction orthogonal to the moving direction, and a pair of GMR elements is replaced with a pair of GMR elements. Are arranged so that the straight line connecting the centers of the two is perpendicular to the moving direction of the magnetic body.

  In order to detect the rotation of the gear made of a magnetic material using the magnetic sensor according to the present invention, the plane on which the pair of GMR elements is arranged faces the outer peripheral surface of the gear teeth and the pair of GMR elements. The magnetic sensor is arranged with respect to the gear so that the straight line connecting the centers of the two is orthogonal to the rotation direction of the gear. When the gear is rotated, the resistance value of the pair of GMR elements changes in the opposite direction in accordance with the movement of the magnetic material, and a sinusoidal signal corresponding to the rotation of the gear from the pair of bridge-connected GMR elements. Is obtained. As can be seen from the second experimental result described later (see FIG. 8), even if the gear pitch changes, a highly accurate sinusoidal signal can be obtained as an output voltage, and the rotational position of the gear can be determined with high accuracy. Can be detected. The magnetic sensor according to the present invention can also be used to detect the movement of a magnetic body other than a gear. However, the output in this case does not change sinusoidally. In the magnetic sensor of the present invention, a pair of magnetic field strength detection type GMR elements may be configured in the same manner and arranged in a plane. For example, a pair of GMR elements having the same configuration is disposed on a base such as an insulating substrate. What is necessary is just to form, and a magnetic sensor can be comprised easily.

  Another feature of the present invention is that the pair of GMR elements have shape anisotropy in the longitudinal direction and the short side direction, and the pair of GMR elements is connected to the straight line connecting the centers of the pair of GMR elements. It is arranged so as to be orthogonal to. According to this, as can be seen from a first experimental result (see FIG. 7) described later, the sensitivity difference is higher than that in the case where the longitudinal direction is parallel to the straight line connecting the centers of the pair of GMR elements. The directivity can be obtained and a large output can be obtained.

  Another feature of the present invention is that the first set of GMR elements (22a, 22b or 22c, 22d) including at least a pair of magnetic field intensity detection type GMR elements that are identically configured and bridge-connected, A second set of GMR elements (22a, 22b or 22c, 22d) composed of at least a pair of magnetic field intensity detection type GMR elements, each of which is configured identically with the pair of GMR elements and bridge-connected; A magnetic sensor comprising bias magnetic field applying means (60) for applying a bias magnetic field to each of the GMR element and the second pair of GMR elements, wherein the first pair of GMR elements are arranged in the same plane. The second pair of GMR elements are spaced apart from each other by a predetermined distance in the plane, and a straight line connecting the centers of the second pair of GMR elements is the first set. The bias magnetic field applying means is arranged parallel to the straight line connecting the centers of the pair of GMR elements with a predetermined distance, and the bias magnetic field applying means is connected to the straight line connecting the centers of the first pair of GMR elements and the second in the plane. The bias magnetic fields having the same strength in opposite directions are inclined with respect to the direction perpendicular to the straight line connecting the centers of the pair of GMR elements, and the opposite pair of the same bias magnetic fields are applied to the first pair of GMR elements and the second pair of GMR elements. The arrangement is such that they are applied to the pair of GMR elements, respectively.

  In another aspect of the present invention, in order to detect the rotation of the gear made of a magnetic material, the plane on which the first and second pairs of GMR elements are arranged faces the outer peripheral surface of the gear teeth. The magnetic sensor is arranged with respect to the gear so that a straight line connecting the centers of the pair of GMR elements is orthogonal to the rotation direction of the gear. When the gear is rotated, as described above, sinusoidal signals corresponding to the rotation of the gear can be obtained from the first and second pair of GMR elements connected in a bridge manner. The pair of GMR elements of the first group and the second group is such that a straight line connecting the centers of the second pair of GMR elements is parallel to a straight line connecting the centers of the first pair of GMR elements at a predetermined distance. Therefore, the sinusoidal signal obtained from the second pair of bridge-connected GMR elements is different from the sinusoidal signal obtained from the first pair of bridge-connected GMR elements. Is different. Therefore, according to this, the rotation angle of the gear can be detected easily and with high accuracy using two sinusoidal signals having different phases.

It is a top view which shows schematic structure in the chip package of the magnetic sensor which concerns on 1st Embodiment of this invention. FIG. 2 is an enlarged plan view of a sensor chip in the magnetic sensor of FIG. 1. It is a perspective view of the magnetic sensor of FIG. It is a bridge circuit diagram of the magnetic sensor of FIG. It is a perspective view which shows the detection state of rotation of the magnetic body gear by the magnetic sensor of FIG. It is a graph which shows the change characteristic of the resistance value of the GMR element with respect to the applied magnetic field intensity. It is a graph which shows the sensitivity anisotropy by the bias magnetic field direction of the GMR element bridge-connected. (A), (B), and (C) are waveform diagrams of detection signals obtained by detecting the rotation of three types of magnetic gears having different uneven pitches by the magnetic sensor of FIG. 1 (magnetic sensor according to the first embodiment). is there. It is a top view which shows schematic structure in the chip package of the magnetic sensor which concerns on a comparative example. FIG. 10 is an enlarged plan view of a sensor chip in the magnetic sensor of FIG. 9. It is a perspective view which shows the detection state of rotation of the magnetic body gear by the magnetic sensor of FIG. (A), (B), and (C) are waveform diagrams of detection signals obtained by detecting the rotation of three types of magnetic gears having different uneven pitches by the magnetic sensor of FIG. 9 (magnetic sensor according to a comparative example). FIG. 9 is a graph showing a comparison between the output value of the magnetic sensor of FIG. 1 (magnetic sensor according to the first embodiment) and the output value of the magnetic sensor of FIG. 9 (magnetic sensor according to a comparative example) with respect to the uneven pitch of the magnetic gear. is there. It is a top view which shows schematic structure in the chip package of the magnetic sensor which concerns on 2nd Embodiment of this invention. It is a perspective view of the magnetic sensor of FIG. It is an output voltage waveform figure of the magnetic sensor (magnetic sensor which concerns on 2nd Embodiment) of FIG. It is the schematic which shows the example which applied the magnetic sensor to the detection of the movement of magnetic bodies other than a gearwheel.

a. First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a schematic configuration in a chip package 10 of the magnetic sensor according to the first embodiment. 2 is an enlarged plan view of the sensor chip 20 in the magnetic sensor of FIG. 1, and FIG. 3 is a perspective view of the magnetic sensor of FIG. In this specification, the vertical direction in FIG. 1 is the front-rear direction of the magnetic sensor (the lower side in FIG. 1 is the front side of the magnetic sensor, the upper side in FIG. 1 is the rear side of the magnetic sensor), and the horizontal direction in FIG. The description will be made assuming that the magnetic sensor is the left-right direction and the front-back direction of the paper surface in FIG.

  The chip package 10 is configured in a rectangular parallelepiped shape with an epoxy resin. In the chip package 10, an island portion 11 made of a nonmagnetic conductive material (for example, a copper plate) in a thin plate shape and parallel to the upper and lower surfaces at a substantially central position in the vertical direction of the chip package 10, a protruding portion 12a, 12b and lead frame portions 13a to 13d are incorporated.

  The island part 11 is formed in a rectangular shape in plan view, and is arranged at the center position in the left-right direction of the chip package 10 and at a slightly rear position in the front-rear direction. The left and right sides and the front and rear sides of the island portion 11 are parallel to the left and right sides and the front and rear sides of the chip package 10, respectively. The projecting portions 12 a and 12 b are integrally formed with the island portion 11 in a bowl shape in plan view, the rear end of the inner end portion is connected to the front end of the island portion 11, and the front end of the outer end portion is the front surface of the chip package 10. It protrudes from. The projecting portions 12a and 12b flow into the periphery of the island portion 11 when the island portion 11, the projecting portions 12a and 12b, and the lead frame portions 13a to 13d are fixed in the chip package 10. 11 is provided to support 11. The lead frame portions 13a to 13d also have a bowl shape in plan view, and their front end portions are positioned in the vicinity of the front portion of the island portion 11, and their rear end portions are projected from the rear surface of the chip package 10. .

  A sensor chip 20 is fixed to the front upper surface of the island part 11. The sensor chip 20 includes an insulating substrate 21 configured in a rectangular plate shape with an insulating material such as silicon, glass, or ceramic. In this embodiment, the insulating substrate 21 has a length L1 in the front-rear direction set to 1.05 mm, a length L2 in the left-right direction set to 1.8 mm, and a thickness set to 0.4 mm. The insulating substrate 21 is fixed to the upper surface of the island portion 11 by a die bond material with the left and right sides and front and rear sides thereof being parallel to the left and right sides and front and rear sides of the chip package 10, respectively.

  On the upper surface of the insulating substrate 21, GMR elements (giant magnetoresistive effect elements) 22a to 22d and electrodes 23a to 23d are arranged. The GMR elements 22a to 22d are composed of a linear granular thin film made of Ag—FeCo, and are formed on the insulating substrate 21 by depositing the granular thin film on the upper surface of the insulating substrate 21 using a sputtering method. Has been. The GMR elements 22a and 22d are formed in a rectangular region 21a provided on the left side and the front portion of the upper surface of the insulating substrate 21, and the GMR elements 22b and 22c are formed on the rectangular region 21b provided on the right side and the front portion of the upper surface of the insulating substrate 21. A film is formed. The rectangular regions 21a and 21b have the same shape and size, and the length in the front-rear direction is larger than the length in the left-right direction. The left and right sides of the rectangular regions 21a and 21b are parallel to the left and right sides of the insulating substrate 21 and the chip package 10, respectively, and the front and rear sides of the rectangular regions 21a and 21b are parallel to the front and rear sides of the insulating substrate 21 and the chip package 10, respectively. . Further, the rectangular regions 21a and 21b have the same position in the front-rear direction, that is, the distances from the front sides of the rectangular regions 21a and 21b to the front sides of the insulating substrate 21 and the chip package 10 are the same, and the rectangular regions 21a and 21b. Is located symmetrically with respect to the center line CL1 of the insulating substrate 21 in the left-right direction. In these rectangular regions 21a and 21b, in the present embodiment, the length L3 in the front-rear direction is set to 0.4825 mm, and the length L4 in the left-right direction is set to 0.3 mm. The length L5 from the right end of the rectangular area 21a to the left end of the rectangular area 21b is set to 0.92 mm in this embodiment. The distance L6 between the centers of the GMR elements 22a and 22d and the centers of the GMR elements 22b and 22c is 1.22 mm.

  The GMR elements 22a and 22d are formed on the rectangular region 21a in a linear shape having a plurality of folded portions, with the longitudinal direction being the front-rear direction and the short direction being the left-right direction. More specifically, the GMR elements 22a, 22d are folded in a straight line in the rectangular region after extending a predetermined length (a little shorter than the length L3) in a straight line. The extending front end portion or rear end portion is curved and extended in the left-right direction by a certain length, and further extending in a straight line in the direction opposite to the straight line extending direction is repeated.

  Further, the GMR elements 22a and 22d are folded back so as to have a portion in which the distance between the adjacent linear portions in the left-right direction is increased and a portion in which the distance between the adjacent linear portions in the left-right direction is decreased. Yes. Then, a portion of the GMR element 22a in which the horizontal interval between adjacent linear portions in the GMR element 22d is increased, and a portion in which the distance in the horizontal direction of the adjacent linear portion in the GMR element 22d is reduced is intruded. A portion of the GMR element 22a in which the space in the left-right direction is reduced is inserted into a portion in which the space in the left-right direction of the matching linear portion is increased. The number of times the GMR elements 22a and 22b are folded is set such that the number of straight portions extending in the front-rear direction of the GMR elements 22a and 22d is 17, for example.

  The GMR elements 22b and 22c are linearly formed on the rectangular region 21b with a plurality of folded portions, with the longitudinal direction being the front-rear direction and the short direction being the left-right direction. The GMR elements 22b and 22c are configured similarly to the GMR elements 22a and 22d. The GMR element 22b is arranged so as to be symmetrical with the GMR element 22a with respect to the center line CL1. Further, the GMR element 22c is arranged so as to be symmetrical with the GMR element 22d with respect to the center line CL1.

  The electrodes 23a to 23d are made of a non-magnetic conductive material (for example, aluminum) in a thin plate shape, and are patterned in a square shape on the insulating substrate 21 in plan view. The electrode 23a is located behind the GMR elements 22b and 22c, and the electrode 23b is located behind the GMR elements 22a and 22d. The electrodes 23a and 23b are arranged symmetrically with respect to the center line CL1. The electrode 23c is located to the left of the GMR elements 22b and 22c and between the center line CL1 and the GMR elements 22b and 22c, and the electrode 23d is located to the right of the GMR elements 22a and 22d and the center line CL1 and GMR. Located between elements 22a and 22d. The electrodes 23a and 23b are arranged symmetrically with respect to the center line CL1.

  On the insulating substrate 21, wiring patterns 24 for electrically connecting the GMR elements 22a to 22d and the electrodes 23a to 23d are formed. The wiring pattern 24 is also composed of a thin plate-like nonmagnetic conductor material (for example, aluminum). One end (upper right end) of the GMR element 22a is electrically connected to the electrode 23a by the wiring pattern 24, and the other end (lower left end) of the GMR element 22a is connected to the electrode 23c by the wiring pattern 24. One end (lower right end) of the GMR element 22 b is electrically connected to the electrode 23 b by the wiring pattern 24, and the other end (upper left end) of the GMR element 22 b is connected to the electrode 23 c by the wiring pattern 24. Thereby, the GMR elements 22a and 22b are half-bridge connected. Further, one end (upper left end) of the GMR element 22c is electrically connected to the electrode 23a by the wiring pattern 24, and the other end (lower right end) of the GMR element 22c is connected to the electrode 23d by the wiring pattern 24. One end (lower left end) of the GMR element 22d is electrically connected to the electrode 23b by the wiring pattern 24, and the other end (upper right end) of the GMR element 22d is connected to the electrode 23d by the wiring pattern 24. Thereby, the GMR elements 22c and 22d are also half-bridge connected.

  The electrodes 23a to 23d are electrically connected to the lead frame portions 13a to 13d via wires 14a to 14d made of conductive wires (for example, gold wires). The lead frame portion 13a is supplied with a voltage V from an external electric circuit device, and the lead frame portion 13b is grounded by the electric circuit device. The lead frames 13c and 13d output voltages O1 and O2 to the electric circuit device, respectively. As a result, the GMR elements 22a to 22d constitute a full bridge circuit as shown in FIG. The electric circuit device includes a differential amplifier 25, and the differential amplifier 25 outputs a differential voltage between the output voltages O1 and O2.

  A rectangular parallelepiped bias magnet 30, which is a permanent magnet, is fixed to the lower surface of the chip package 10 with a die bond material. In this embodiment, the bias magnet 30 is composed of a neodymium magnet mainly composed of neodymium and iron, and the lengths L7 and L8 of the upper and lower surfaces are set to 7 mm and 3 mm, respectively, and the thickness L9 is set to 9 mm. It is set to 3mm. The bias magnet 30 is polarized with a plane that bisects the thickness direction as a boundary and is magnetized in two poles in a direction perpendicular to the boundary surface. The upper side is an N pole, and the lower side is S pole. The bias magnet 30 has its upper surface centered at the intersection of the center line CL2 passing through the centers of the GMR elements 22a and 22d and the GMR elements 22b and 22c and the center line CL1, and both of the upper surfaces of the bias magnet 30 are disposed. A center line CL3 passing through the center between the long sides is inclined by a predetermined angle (45 degrees in this embodiment) with respect to the center line CL2. As a result, the bias magnet 30 generates a magnetic field in the direction of the arrow indicated on the GMR elements 22a to 22d in FIG. 1, and the GMR elements 22a to 22d are each in the longitudinal direction, that is, the predetermined angle with respect to the center line CL1. A bias magnetic field in an inclined direction is applied (45 degrees in this embodiment). However, the direction of the bias magnetic field applied to the GMR elements 22a and 22d is opposite to the direction of the bias magnetic field applied to the GMR elements 22b and 22c. In the present embodiment, the distance from the upper surface of the bias magnet 30 to the GMR elements 22a to 22d is set to 1.0 mm.

  The magnetic sensor configured as described above is manufactured as follows. First, the electrodes 23 a to 23 d and the wiring pattern 24 are formed on the insulating substrate 21. Then, GMR elements 22a to 22d are formed by forming a granular thin film on the upper surface of the insulating substrate 21 by using a sputtering method. Contrary to the above, the electrodes 23a to 23d and the wiring pattern 24 may be formed after the GMR elements 22a to 22d are formed. Thereby, the sensor chip 20 in which the GMR elements 22a to 22d, the electrodes 23a to 23d, and the wiring pattern 24 are provided on the insulating substrate 21 is completed.

  Next, the island part 11, the projecting parts 12a and 12b, and the lead frame parts 13a to 13d are arranged at the positions shown in FIG. 1, and the lower surface of the insulating substrate 21 is bonded to the upper surface of the island part 11 by a die bond material. The sensor chip 20 is fixed on the island part 11. In this case, contrary to the above, after the sensor chip 20 is fixed on the island part 11, the island part 11, the projecting parts 12a and 12b, and the lead frame parts 13a to 13d are arranged at the positions shown in FIG. May be. Next, both ends of the wires 14a to 14d are connected to the electrodes 23a to 23d and the lead frame portions 13a to 13d by wire bonding (ultrasonic heating connection), respectively, and the electrodes 23a to 23d and the lead frame portions 13a to 13d are connected to the wires. Electrical connection is made via 14a to 14d.

  Thereafter, using the epoxy resin, the sensor chip 20, the island portion 11, the rear portions of the protruding portions 12a and 12b, the front portions of the lead frame portions 13a to 13d, and the wires 14a to 14d are accommodated inside, and the protruding portions 12a, The chip package 10 in which the front part of 12b and the rear parts of the lead frame parts 13a to 13d are projected is molded. Next, the upper surface of the pre-magnetized bias magnet 30 is bonded to the lower surface of the chip package 10 with a die bond material, thereby completing a magnetic sensor in which the chip package 10 and the bias magnet 30 are integrated.

  In the magnetic sensor manufactured as described above, the electrodes 23a to 23d and the wiring pattern 24 are formed on the insulating substrate 21, and the GMR elements 22a to 22d are formed on the insulating substrate 21 by forming a granular thin film. Thus, the sensor chip 20 is manufactured. The sensor chip 20 is fixed to the island part 11, and the electrodes 23a to 23d and the lead frames 13a to 13d are electrically connected by the wires 14a to 14d, and the sensor chip 20, the island part 11, and the protruding part 12a are molded by molding. , 12b, lead frame portions 13a to 13d and wires 14a to 14d are manufactured. Since the magnetic sensor is completed simply by fixing the bias magnet 30 to the chip package 10, the magnetic sensor can be easily manufactured.

  Next, a magnetic body movement detection device that detects the rotation of the gear 40, which is a magnetic body, using the magnetic sensor thus manufactured will be described. In the gear 40, square-shaped convex portions (teeth) 41 and concave portions having the same shape and size are alternately arranged on a circular outer peripheral surface. As shown in FIG. 5, in the magnetic sensor, the upper surface of the chip package 10 faces the outer peripheral surface of the tooth 41 of the gear 40 in parallel, and the front and rear direction of the chip package 10 (sensor chip 20) (center line CL1 in FIG. 1). Of the GMR elements 22a to 22d is aligned with the rotation direction of the gear 40 so that the longitudinal direction of the GMR elements 22a to 22d is aligned with the rotation direction of the gear 40. Be placed. In the first embodiment, the distance from the upper surface of the GMR elements 22a to 22d to the outer peripheral surface of the one tooth 41 is set to 0.8 mm. The rotation direction of the gear 40 is a direction indicated by an arrow on the right side of the chip package 10 in FIG. 1, and an arrow direction indicated on the lower side of the gear 40 in FIG. 5.

  When the gear 40 is rotated in a state where the magnetic sensor is arranged with respect to the gear 40 in this manner, the magnetic field passing through the GMR elements 22a and 22d in parallel to the element surfaces and the GMR elements 22b and 22c are changed to those. Magnetic fields that pass in parallel to the element surface are in opposite directions, and their magnetic field strengths change almost sinusoidally with a phase difference of 180 degrees. Specifically, a magnetic field strength that is a magnetic field that passes through the GMR elements 22a and 22d in parallel to the element surfaces and has a component opposite to the rotation direction of the gear 40 (this magnetic field strength is defined as a positive applied magnetic field strength). Is a positive predetermined strength when the GMR elements 22a and 22d are in the middle position between the two adjacent teeth 41, and gradually decreases from the positive predetermined strength as the gear 40 rotates, and then decreases. When the GMR elements 22a and 22d come to a position facing the one tooth 41, the positive predetermined strength is almost restored. When the gear 40 further rotates, the positive applied magnetic field intensity gradually becomes smaller than the predetermined positive value and then increases, and when the GMR elements 22a to 22d come to an intermediate position between the two adjacent teeth 41. Return to the positive predetermined intensity. The change in the positive applied magnetic field strength is substantially sinusoidal.

  On the other hand, the magnetic field strength passing through the GMR elements 22b and 22c in parallel to their element surfaces and having the same direction component as the rotation direction of the gear 40 (this magnetic field strength is defined as a negative applied magnetic field strength) is The GMR elements 22b and 22c have a negative predetermined strength when they are at an intermediate position between the two adjacent teeth 41. The GMR elements 22b and 22c gradually increase from the negative predetermined strength as the gear 40 rotates and then increase. When 22a-22d comes to the position which opposes one tooth | gear 41, it will return to the said negative predetermined intensity | strength substantially. When the gear 40 further rotates, the negative applied magnetic field strength gradually increases from the negative predetermined strength and then decreases, and when the GMR elements 22a to 22d come to an intermediate position between the two adjacent teeth 41. , Return to the negative predetermined intensity. The change in the negative applied magnetic field strength is also substantially sinusoidal. The absolute values of the positive predetermined intensity and the negative predetermined intensity are equal.

  As can be understood from the change characteristic of the resistance value of the GMR element with respect to the applied magnetic field strength shown by the solid line in FIG. 6 due to the change in the positive applied magnetic field strength, the time required for the gear 40 to rotate by one pitch of the teeth 41 is 1 As a cycle, the resistance values of the GMR elements 22a to 22d change in a substantially sine wave shape. The resistance value changes of the GMR elements 22b and 22c differ in phase by 180 degrees (1/2 pitch of the tooth 41 of the gear 40) with respect to the resistance value changes of the GMR elements 22a and 22d.

  Therefore, the electric circuit device shown in FIG. 4 represents the rotation of the gear 40 made of a magnetic material, and is shown in FIGS. 8A to 8C, which consists of a sine wave signal with one pitch of the teeth 41 as one cycle. Such an output voltage signal is extracted. In this case, the GMR elements 22a to 22d are full-bridge connected, and the differential voltage between the output voltages O1 and O2 is output from the differential amplifier 25. Therefore, a rotation detection signal of the gear 40 having a large amplitude value can be obtained.

    Next, the effect of detecting the rotation of the gear 40 using the magnetic sensor of the first embodiment will be described based on experimental results.

a1. First Experiment Result First, an external magnetic field is applied to the magnetic sensor of the first embodiment in which the bias magnet 30 is fixed to the chip package 10 to measure the output voltage (differential voltage) of the differential amplifier 25 of the electric circuit device. did. In this case, the external magnetic field is applied in the direction of the center line CL1 (see FIG. 1), that is, the longitudinal direction of the GMR elements 22a to 22d, and the magnetic field intensity is changed positively and negatively to apply the external magnetic field to the GMR elements 22a to 22d. . As for the direction of the external magnetic field, the direction opposite to the rotation direction of the gear 40 indicated by the arrow in FIG. 1 (upward direction in FIG. 1) is the positive direction, and the rotation direction (downward direction in FIG. 1) is the negative direction. . Specifically, the external magnetic field strength was gradually increased from 0 KA / m to about 22 KA / m, then gradually decreased to about −22 KA / m, and then increased to 0 KA / m. The application of the external magnetic field corresponds to the change in the applied magnetic field to the GMR elements 22a to 22d due to the rotation of the gear 40 described above.

  Then, the output voltage value of the differential amplifier 25 was measured for each change of the external magnetic field strength by a predetermined value. The measurement result is shown by a solid line in the graph of FIG. According to this, it can be seen that an output characteristic having high linear characteristics and no hysteresis was obtained in a wide operating magnetic field range.

  Next, using the same magnetic sensor of the first embodiment as in the above measurement, the direction of application of the external magnetic field is set to the direction of the center line CL2 (see FIG. 1), that is, the short direction of the GMR elements 22a to 22d. An external magnetic field was applied to the GMR elements 22a to 22d while changing between positive and negative. As for the direction of the external magnetic field, the left direction in FIG. 1 is a positive direction, and the right direction in FIG. 1 is a negative direction. Then, the external magnetic field intensity was changed in the range of about −22 KA / m to about 22 KA / m, as in the above case.

  Then, the output voltage value of the differential amplifier 25 was measured for each change of the external magnetic field strength by a predetermined value. The measurement result is indicated by a broken line in the graph of FIG. This also shows that an output characteristic having a high linear characteristic and no hysteresis was obtained in a relatively wide operating magnetic field range. However, from this measurement result, when the application direction of the external magnetic field is the short direction of the GMR elements 22a to 22d, the output is larger than when the application direction of the external magnetic field is the longitudinal direction of the GMR elements 22a to 22d. The change in voltage value is reduced by about 15 to 20%. That is, when the application direction of the external magnetic field is set to the longitudinal direction of the GMR elements 22a to 22d, it is about 15 to 20% higher than the case where the application direction of the external magnetic field is set to the short direction of the GMR elements 22a to 22d. It was found that sensitivity anisotropy was obtained.

  Considering this, the solid line in FIG. 6 is a general graph showing the change characteristic of the resistance value of the GMR element with respect to the applied magnetic field strength when the longitudinal direction of the GMR element is set as the magnetic field application direction. The broken line in FIG. 6 is a general graph showing the change characteristic of the resistance value of the GMR element with respect to the applied magnetic field strength when the short direction of the GMR element is set as the magnetic field application direction. That is, regarding the sensitivity anisotropy, the resistance value of the GMR element with respect to the applied magnetic field strength is greater when the longitudinal direction is the magnetic field application direction than when the short direction is the magnetic field application direction. It can also be understood from the fact that the change is large.

  From the results of the first experiment, it can be seen that changing the magnetic field strength in the longitudinal direction of the GMR elements 22a to 22d is preferable to changing the magnetic field strength in the short direction of the GMR elements 22a to 22d. Therefore, it is preferable to arrange the magnetic sensor with respect to the gear 40 so that the longitudinal direction of the GMR elements 22a to 22d coincides with the rotational direction of the gear 40 as in the first embodiment. As a result, in the rotation detection of the gear 40 of the first embodiment, it is possible to obtain a sinusoidal output voltage having a large amplitude and high accuracy.

a2. Second Experimental Result Next, with respect to the gear 40 having a different gear pitch, a magnetic sensor was arranged as in the first embodiment, and the output voltage was measured by rotating the gear 40. The gear pitch referred to here is a circle between two points where two straight lines connecting the center of the rotation width of the two adjacent teeth 41 and the rotation center of the gear 40 intersect the outer peripheral surface of the adjacent tooth 41. It is the length in the circumferential direction, that is, the length of the arc between the two points, not the linear distance. Moreover, the electrical angle in the next FIG. 8 corresponds to one gear pitch corresponding to 360 degrees.

  8A shows the measurement results when the gear pitch is 2.36 mm, FIG. 8B shows the measurement results when the gear pitch is 3.14 mm, and FIG. 8C shows the gear pitch. It is a measurement result in case that is 4.71 mm. 8A, 8 </ b> B, and 8 </ b> C, the change in the output voltage as a measurement result is indicated by a solid line, and the sine waveform is indicated by a broken line for comparison between the output voltage waveform and the sine waveform.

  According to the results of the second experiment, when the gear pitch is reduced, the amplitude value of the output voltage is reduced, but in any case, the output voltage changes in a substantially sine wave shape. As a result, if the magnetic sensor is arranged with respect to the gear 40 as in the first embodiment using the magnetic sensor configured as in the first embodiment, even if the gear pitch is changed, high accuracy is achieved. A sine wave signal can be obtained as an output voltage, and the rotational position of the gear 40 can be detected with high accuracy.

a3. Third Experiment Result Next, as described in the background art (Patent Document 1), the magnetic sensor is arranged so that the straight line connecting the centers of the pair of GMR elements is the rotation direction of the gear, and the rotation of the gear is The measurement result is compared with the measurement result of the first embodiment.

  In this case, also in the magnetic sensor to be compared, as shown in FIG. 9, the island portion 11 and the protruding portion of the first embodiment are included in the chip package 10 ′ similar to the chip package 10 of the first embodiment. 12a, 12b and lead frame parts 13a-13d are incorporated with island parts 11 ', projecting parts 12a', 12b 'and lead frame parts 13a'-13d'.

  A sensor chip 20 'is fixed on the upper surface of the front portion of the island portion 11'. In the sensor chip 20 ′, the lower surface of the insulating substrate 21 ′ is fixed to the upper surface of the island portion 11 ′ in the same manner as the insulating substrate 21 of the first embodiment. Further, as shown in FIG. 10, electrodes 23a ′ to 23d ′ and a wiring pattern 24 ′ similar to the electrodes 23a to 23d and the wiring pattern 24 of the first embodiment are provided on the upper surface of the insulating substrate 21 ′. Yes. The electrodes 23a 'to 23d' are electrically connected to the lead frame portions 13a 'to 13d' by wires 14a 'to 14d' similar to the wires 14a to 14d of the first embodiment.

  Also in this case, as shown in FIG. 10, on the insulating substrate 21 ′, GMR elements 22a ′ and 22d ′ are arranged in a rectangular region 21a ′ provided on the left side and the front side portion of the upper surface of the insulating substrate 21 ′. The GMR elements 22b ′ and 22c ′ are arranged on the right side and the front side portion of the upper surface of the insulating substrate 21 ′. These GMR elements 22a 'to 22d' are also formed of a granular thin film as in the case of the first embodiment. However, the GMR elements 22a 'and 22d' are formed on the rectangular region 21a 'in a linear shape having a plurality of folded portions, the longitudinal direction being the left-right direction and the short direction being the front-rear direction. The GMR elements 22b 'and 22c' are formed on the rectangular region 21b 'in a linear shape having a plurality of folded portions with the longitudinal direction being the left-right direction and the short direction being the front-rear direction.

  The GMR elements 22a 'and 22b' are arranged symmetrically with respect to the center line CL1 'in the left-right direction of the insulating substrate 21'. The GMR elements 22c 'and 22d' are also arranged symmetrically with respect to the center line CL1 '. The areas of the rectangular regions 21a ′ and 21b ′ are the same as the areas of the rectangular regions 21a and 21b of the first embodiment, and the widths, longitudinal directions, and short sides of the linear portions of the GMR elements 22a ′ to 22d ′ are used. The total length in the direction is also the same as the width of the linear portions of the GMR elements 22a to 22d of the first embodiment, and the total length in the longitudinal direction and the short direction. Further, the distance L10 (element pitch) between the center position of the GMR elements 22a ′ and 22d ′ (rectangular area 21a ′) and the center position of the GMR elements 22b ′ and 22c ′ (rectangular area 21b ′) is the first embodiment. It is the same 1.22 mm as in the case of.

  A rectangular parallelepiped bias magnet 30 ′ composed of neodymium magnets mainly composed of neodymium and iron is fixed to the lower surface of the chip package 10 ′, similarly to the bias magnet 30 of the first embodiment. In the bias magnet 30 ', the upper and lower surfaces are square, the length of each side is set to 3 mm and 3 mm, respectively, and the thickness is set to 5 mm. The bias magnet 30 'is also polarized with a plane that bisects the thickness direction as a boundary and is magnetized in two poles in a direction perpendicular to the boundary surface, and the upper side is an N pole. The lower side is the S pole. Then, the bias magnet 30 ′ has the center position of the upper surface facing the intersection of the center line CL1 ′ and the center line CL2 ′ passing through the centers of the GMR elements 22a ′ and 22d ′ and the GMR elements 22b ′ and 22c ′. And a pair of sides in the front-rear direction on the upper surface thereof are parallel to the center line CL1 ′. As a result, the bias magnet 30 'generates a magnetic field in the direction indicated by the arrow on the GMR elements 22a' to 22d 'in FIG. 9, and a bias magnetic field is applied to each of the GMR elements 22a' to 22d 'in the longitudinal direction. The Also in this case, the direction of the bias magnetic field applied to the GMR elements 22a 'and 22d' is opposite to the direction of the bias magnetic field applied to the GMR elements 22b 'and 22c'. Also in this case, the distance from the upper surface of the bias magnet 30 ′ to the GMR elements 22 a ′ to 22 d ′ is set to 1.0 mm.

  Even in the detection of the rotation of the gear 40 similar to that in the first embodiment using the magnetic sensor configured as described above, the upper surface of the chip package 10 ′ is placed on the outer peripheral surface of the gear 40 as shown in FIG. Opposed in parallel, they are arranged with respect to the gear 40 by fixing parts (not shown). However, in this case, in the magnetic sensor, the left and right direction (the direction of the center line CL2 ′) of the chip package 10 ′ matches the rotation direction of the gear 40 (the moving direction of the teeth 41), that is, the GMR elements 22a ′ to 22d ′. Are arranged with respect to the gear 40 so that the longitudinal direction of the gear matches the rotational direction of the gear 40. Also in this case, the distance from the upper surface of the GMR elements 22a 'to 22d' to the one tooth 41 is set to 0.8 mm. Note that the rotation direction of the gear 40 is a direction indicated by an arrow on the right side of the chip package 10 in FIG. 9, and an arrow direction indicated on the lower side of the gear 40 in FIG. 11.

  When the gear 40 is rotated in a state where the magnetic sensor is arranged with respect to the gear 40 in this way, a magnetic field passing through the GMR elements 22a ′ and 22d ′ in parallel to the element surfaces, and the GMR elements 22b ′, The magnetic fields passing through 22c 'in parallel to the element surfaces are in opposite directions, and their magnetic field strengths change substantially sinusoidally with a phase difference of 180 degrees. The specific change in magnetic field strength is the same as that in the first embodiment described above. When the GMR elements 22a ′ to 22d ′ are connected to the electric circuit device as described in the first embodiment (see FIG. 4), the rotation of the gear 40 is represented, and one pitch of the teeth 41 is defined as one cycle. The output voltage signal as shown in FIGS. 12A to 12C is extracted.

  12A shows the measurement results when the gear pitch is 2.36 mm, FIG. 12B shows the measurement results when the gear pitch is 3.14 mm, and FIG. 12C shows the gear pitch. It is a measurement result in case that is 4.71 mm. 12A, 12B, and 12C, the change in the output voltage as a measurement result is shown by a solid line, and the sine waveform is shown by a broken line for comparison between the output voltage waveform and the sine waveform.

  Also according to the result of the second experiment, the amplitude value of the output voltage decreases as the gear pitch decreases. When the gear pitch is 3.14 mm, as shown in FIG. 12B, the output voltage waveform changes almost sinusoidally. However, when the gear pitch is 2.36 mm and when the gear pitch is 4.71 mm, the output voltage waveform does not change in a sine wave shape. That is, in the conventional rotation detection of the gear 40 by the magnetic sensor shown in the prior art, the output voltage waveform changes greatly according to the gear pitch and deviates greatly from the sine waveform. As a result, according to the first embodiment (present system), a highly accurate sine wave signal can be obtained as an output even when the gear pitch is changed as compared with the prior art (conventional system). It is possible to detect the rotational position of the gear with high accuracy.

  Further, FIG. 13 shows the voltage difference between the peaks of the output voltage according to the first embodiment (this method) when the gear pitch is changed by a solid line, and the peak of the output voltage according to the prior art (conventional method). The voltage difference between them is indicated by a broken line. According to this, it can also be understood that according to the first embodiment (present method), a large output voltage can be obtained in a region where the gear pitch is small as compared with the case of the prior art (conventional method).

b. Second Embodiment Next, a magnetic sensor that outputs a two-phase signal representing the rotation of the gear 40, which is a magnetic body, will be described. FIG. 14 is a plan view showing a schematic configuration in the chip package 50 of the magnetic sensor according to the second embodiment. FIG. 15 is a perspective view of the magnetic sensor of FIG. Also in the second embodiment, the vertical direction of FIG. 14 is the front-rear direction of the magnetic sensor (the lower side of FIG. 14 is the front side of the magnetic sensor and the upper side of FIG. 14 is the rear side of the magnetic sensor). Is the left-right direction of the magnetic sensor, and the front-back direction of the paper surface in FIG. 14 is the vertical direction of the magnetic sensor.

  The chip package 50 is formed in a rectangular parallelepiped shape with an epoxy resin, as in the first embodiment. However, the chip package 50 is disposed to be inclined with respect to the front-rear direction (and left-right direction) of the magnetic sensor. Also in this case, in the chip package 50, an island portion formed of a non-magnetic conductive material (for example, a copper plate) in a thin plate shape in parallel with the upper and lower surfaces at a substantially central position in the vertical direction of the chip package 50. 51, protrusions 52a and 52b, and lead frame portions 53a to 53h are incorporated.

The island portion 51 is formed in a substantially rectangular shape in plan view, and is arranged at a substantially central position of the chip package 50 with each side being substantially parallel to each side of the upper and lower surfaces of the chip package 50. The protrusions 52a and 52b have the same function as the protrusions 12a and 12b of the first embodiment, and are formed in a long and substantially rectangular shape in plan view. The protruding portion 52 a is integrally formed with the island portion 51 by connecting the lower right end to the island portion 51, and the upper left end protrudes from the upper left side surface of the chip package 50. The protruding portion 52 b has a lower right end protruding from the lower right side surface of the chip package 50. The lead frame portions 53a to 53d and the lead frame portions 53e to 53h have the same functions as the lead frame portions 13a to 13d of the first embodiment, respectively, and are formed in a long and substantially rectangular shape in plan view. Yes. The lead frame portions 53a, 53f, 53g, and 53h have their lower right ends projecting from the lower right side surface of the chip package 50. The lead frame portions 53b, 53c, 53d, and 53e have their upper left ends protruding from the upper left side surface of the chip package 50.
It protrudes from the surface.

  Two sensor chips 20 </ b> A and 20 </ b> B are fixed to the upper surface of the island portion 51. Since these sensor chips 20A and 20B are configured in the same manner as the sensor chip 20 of the first embodiment, their specific configurations are denoted by the same reference numerals as in the first embodiment. Description is omitted.

  The sensor chips 20A and 20B are arranged on the insulating substrate 21 with different front and rear positions and left and right positions, and the sensor chip 20B is arranged on the upper surface of the island portion 51 by rotating the sensor chip 20A by 180 degrees. ing. The center line CL1 in the left-right direction of the insulating substrate 21 in the sensor chip 20A and the center line CL1 in the left-right direction of the insulating substrate 21 in the sensor chip 20B both extend in the front-rear direction, and the two center lines CL1, CL1 are parallel to each other. It is. The center line CL2 passing through the centers of the GMR elements 22a and 22d and the GMR elements 22b and 22c in the sensor chip 20A and the center line CL2 passing through the centers of the GMR elements 22a and 22d and the GMR elements 22b and 22c in the sensor chip 20B are both. The two center lines CL2 and CL2 are parallel to each other.

As for the arrangement of the sensor chips 20A, 20B in the left-right direction, all eight GMR elements 22a-22d need only be within the width in the direction perpendicular to the rotation direction of the teeth 41 of the gear 40, and the sensor chips 20A, 20B. The distance between the center lines CL1 and CL1 is appropriately set. However, since the distance L11 between the center lines CL2 and CL2 of the sensor chips 20A and 20B is related to the phase difference between the two-phase output signals, the distance L11 is set corresponding to the required phase difference between the two-phase output signals. There is a need. Specifically, if the phase difference between the required two-phase output signals is α, when the length of one pitch of the teeth 41 of the gear 40 is Lp, the distance L11 is expressed by the following equation (1). Is set to
(Equation 1)
L11 / Lp = α / 2π

  In the second embodiment, in order to detect the rotation of the gear 40 in which one pitch of the teeth 41 is 3.14 mm and to obtain two output signals having different phases of 90 degrees, the distance L11 is set to the gear 40 described later. It is set to 0.785 mm which is 1/4 of 3.14 mm which is one pitch of the teeth 41.

  The electrodes 23a to 23d of the sensor chip 20A are electrically connected to lead frame portions 53a to 53d via wires 54a to 54d similar to the wires 14a to 14d of the first embodiment, respectively. The electrodes 23a to 23d of the sensor chip 20B are electrically connected to lead frame portions 53e to 53h via wires 55a to 55d similar to the wires 14a to 14d of the first embodiment, respectively. A voltage V is supplied to the lead frame portions 53a and 53e from an external electric circuit device, and the lead frame portions 53b and 53f are grounded by the electric circuit device. The lead frame portions 53c and 53g output voltages O1 and O1 to the electric circuit device, respectively, and the lead frame portions 53d and 53h output voltages O2 and O2 to the electric circuit device, respectively. Accordingly, the GMR elements 22a to 22d of the sensor chip 20A constitute a first full bridge circuit shown in FIG. 4, and the GMR elements 22a to 22d of the sensor chip 20B also constitute a second full bridge circuit shown in FIG. It is to be noted that the electrical circuit device includes the differential amplifiers 25 relating to the first and second full bridge circuits, respectively, which is the same as in the first embodiment, and the output voltages O1, O2 relating to the sensor chips 20A, 20B. A differential voltage is output.

  As shown in FIG. 15, a rectangular parallelepiped bias magnet 60 which is a permanent magnet is fixed to the lower surface of the chip package 50 by a die bond material. The bias magnet 60 is configured in the same manner as in the first embodiment. In this case, the lengths of the long side and the short side of the upper surface and the lower surface are set to 7 mm and 3 mm, respectively, and the thickness is set to 3 mm. Yes. The bias magnet 60 has the center position of the upper surface opposed to the midpoint of a straight line connecting the intersection of both center lines CL1 and CL2 in the sensor chip 20A and the intersection of both center lines CL1 and CL2 in the sensor chip 20B. A center line CL3 passing through the center between both long sides of the upper surface is inclined at a predetermined angle (45 degrees in the present embodiment) with respect to both center lines CL2 and CL2 in the sensor chips 20A and 20B. As a result, the bias magnet 60 generates magnetic fields in the directions indicated by the arrows on the GMR elements 22a to 22d in the sensor chips 20A and 20B in FIG. 14, respectively, and the GMR elements 22a to 22d in the sensor chips 20A and 20B respectively. A bias magnetic field in a direction inclined in the longitudinal direction, that is, the predetermined angle (45 degrees in the present embodiment) with respect to the center lines CL1 and CL1 in the sensor chips 20A and 20B is applied. Also in this case, the direction of the bias magnetic field applied to the GMR elements 22a and 22d in the sensor chips 20A and 20B is opposite to the direction of the bias magnetic field applied to the GMR elements 22b and 22c in the sensor chips 20A and 20B. Also in the second embodiment, the distance from the upper surface of the bias magnet 60 to the GMR elements 22a to 22d in the sensor chips 20A and 20B is set to 1.0 mm.

  The magnetic sensor having the pair of sensor chips 20A and 20B according to the second embodiment configured as described above is also manufactured in the same manner as in the case of the first embodiment. In the detection of the rotation of the gear 40, which is a magnetic material, using the manufactured magnetic sensor, the top surface of the chip package 50 has the teeth 41 of the gear 40 as in the case of the first embodiment. The front and rear direction of the chip package 50 (sensor chips 20A and 20B) (the direction of both center lines CL1 and CL1 in FIG. 14) is the rotational direction of the gear 40 (the moving direction of the teeth 41). In other words, the GMR elements 22a to 22d in the sensor chips 20A and 20B are arranged with respect to the gear 40 by a fixing component (not shown) so that the longitudinal direction of the GMR elements 22a to 22d matches the rotation direction of the gear 40. In this case, one pitch of the teeth 41 of the gear 40 is 3,14 mm. Also in the second embodiment, the distance from the upper surface of the GMR elements 22a to 22d in the sensor chips 20A and 20B to the outer peripheral surface of the one tooth 41 is set to 0.8 mm. Further, the rotation direction of the gear 40 is a direction indicated by an arrow on the right side of the chip package 50 in FIG.

  When the gear 40 is rotated in a state where the magnetic sensor is arranged with respect to the gear 40 as described above, as described in the first embodiment, a pair of electric circuit devices corresponding to the sensor chips 20A and 20B (FIG. 4). From the reference), a pair of sinusoidal differential voltage signals of the first and second full-bridge circuits are respectively output. In this case, the distance L11 between the center line CL2 in the sensor chip 20A and the center line CL2 in the sensor chip 20B orthogonal to the rotation direction of the gear 40 is 1/4 of one pitch of the teeth 41 of the gear 40. Therefore, in the second embodiment, as shown by a solid line and a broken line in FIG. 16, a pair of outputs A and B having a phase difference of 90 degrees can be obtained.

  As a result, a sine wave-like output A and a cosine wave-like output B representing the rotation of the gear 40 can be obtained, and the rotation angle of the gear 40 can be easily determined by arctangent calculation using the outputs A and B. It can also be calculated. Also, in the magnetic sensor according to the first embodiment, the rotation angle of the gear 40 can be calculated, but the accuracy of the detection angle is deteriorated only by the one-phase output near the peak value where the output change is small. In contrast, according to the second embodiment, the rotation angle of the gear 40 can be obtained with high accuracy by using the two-phase outputs A and B.

  In the second embodiment, the two-phase outputs A and B are obtained. However, a multi-phase output may be obtained. In this case, a plurality of sensor chips equal to the number of outputs may be incorporated in the chip package to obtain outputs from the plurality of sensor chips. Then, as in the second embodiment, the center lines of the plurality of sensor chips corresponding to the center line CL2 are orthogonal to the rotation direction of the gear 40, and the intervals between the center lines of the plurality of sensor chips are set to a predetermined distance. As defined, a plurality of sensor chips are incorporated into the chip package. For example, in order to obtain three outputs whose phases are different by 120 degrees, in addition to the sensor chips 20A and 20B of the second embodiment, the center line of another sensor chip corresponding to the center line CL2 is The three sensor chips are incorporated into the chip package so that the distance between the center lines of each sensor chip is 1/3 of one pitch length of the teeth 41 of the gear 40 and is parallel to the center line CL2. do it.

c. Modification In the first and second embodiments, various lengths and distances L1 to L11 are set to predetermined values, but these values can be changed as appropriate. In the first and second embodiments, the bias magnets 30 and 60 are magnetized with the chip package 10 and 50 (sensor chip 20, 20A, 20B) side as the N pole and the opposite side as the S pole. The N pole and the S pole may be reversed. In the first and second embodiments, the island portions 11 and 51 and the projecting portions 12a, 12b, 52a, and 52b are configured by nonmagnetic conductive plates similar to the lead frames 13a to 13d and 53a to 53h. However, since the island portions 11 and 51 and the projecting portions 12a, 12b, 52a, and 52b do not require conductivity, a thin plate made of a material that does not have conductivity may be used as long as it is nonmagnetic.

  In the first and second embodiments, a full bridge circuit is configured by the four GMR elements 22a to 22d, a sine wave output signal is obtained from the full bridge circuit, and the rotation of the gear 40 is detected. I made it. However, although the output value is small, a half bridge circuit is constituted by two GMR elements 22a and 22b (or 22c and 22d), a sine wave output signal is obtained from the half bridge circuit, and the rotation of the gear 40 is detected. You may make it do.

  In the first and second embodiments, the direction of the bias magnetic field generated by the bias magnets 30 and 60 is inclined by 45 degrees with respect to the rotation direction of the gear 40. However, a bias magnetic field in the opposite direction is applied to the GMR elements 22a and 22d and the GMR elements 22b and 22c in the sensor chips 20, 20A and 20B, and the rotation of the gear 40 causes the GMR elements 22a and 22d and the GMR elements 22b and 22c to If the change in the reverse direction of the magnetic field intensity can be obtained, the 45 degree inclination angle may be varied. For example, if the inclination angle is in the range of about 20 to 70 degrees, a sinusoidal output can be obtained and the rotation of the gear 40 can be detected.

  In the first and second embodiments, the GMR elements 22a to 22d using a granular thin film are used as the magnetic field intensity detection type GMR elements that are in-plane magnetosensitive elements. However, instead of this, an artificial lattice type GMR element can be used as a magnetic field intensity detection type GMR element which is an in-plane magnetosensitive element. This artificial lattice type GMR element has a thickness of several angstroms to several tens of angstroms described in a paper entitled “Magnetic Resistance Effect of Artificial Lattice” in Journal of Japan Society of Applied Magnetics Vol.15, No51991, P813 to 821 A laminated body in which magnetic layers and nonmagnetic layers are alternately laminated, so-called artificial lattice films ((Fe / Cr) n, (Permalloy / Cu / Co / Cu) n, (Co / Cu) n, etc.)) Composed.

  In the first and second embodiments, the longitudinal direction of the GMR elements 22a to 22d is made to coincide with the rotational direction of the gear 40, and the magnetic field strength in the longitudinal direction of the GMR elements 22a to 22d is changed by the rotation of the gear 40. I did it. However, the short direction of the GMR elements 22a to 22d may be matched with the rotation direction of the gear 40, and the rotation of the gear 40 may change the magnetic field strength in the short direction of the GMR elements 22a to 22d. This also makes it possible to obtain a sinusoidal output signal corresponding to the rotation of the gear 40, although the amplitude is somewhat reduced as described in the first experimental result. Further, the longitudinal direction (or short direction) of the GMR elements 22a to 22d is inclined with respect to the rotational direction of the gear 40 without matching the longitudinal direction or short direction of the GMR elements 22a to 22d with the rotational direction of the gear 40. You may let them.

  Further, in the first and second embodiments, the GMR elements 22a to 22d that are linearly extended while folding the granular thin film are used as the GMR elements. However, instead of the GMR elements 22a to 22d, spiral GMR elements may be used. The spiral GMR element is formed by extending a linear granular thin film (or artificial lattice film) spirally from the outside to the inside on an insulating substrate, and spirally linear linear thin film from the inner end to the outside. (Or an artificial lattice film) is extended.

  In the first and second embodiments, bias magnets 30 and 60, which are permanent magnets, are used as the bias magnetic field applying means. Instead, a magnetic coil is used and a current is passed through the magnetic coil. A bias magnetic field may be generated.

  In the first and second embodiments, the magnetic sensor is applied to the detection device that detects the rotation of the gear 40 made of a magnetic material. However, the magnetic sensor described above is not the gear 40, but a disc having one or more convex portions 71 formed with irregularities on the outer peripheral surface of a disc-like member 70 made of a magnetic material, as shown in FIG. It can also be applied to the detection of the rotation of the member. Further, the present invention can be applied to rotation detection of a disk-shaped member having one or more recesses on the outer peripheral surface of the disk-shaped member. In this case as well, the magnetic sensor described above may be arranged facing the outer peripheral surface of the convex portion 71 as in the case of the first and second embodiments. Furthermore, the magnetic sensor described above can also be applied to detection of a moving body that is not a rotating body but is made of a magnetic body and has a convex portion or a concave portion and moves linearly. In this case as well, the above-described magnetic sensor may be disposed so as to face the uneven portion of the moving body.

DESCRIPTION OF SYMBOLS 10,50 ... Chip package, 11, 51 ... Island part, 13a-13d, 53a-53h ... Lead frame part, 14a-14d, 54a-54d, 55a-55d ... Wire, 20, 20A, 20B ... Sensor chip, 21 Insulating substrate, 22a to 22d ... GMR element, 23a to 23d ... electrode, 24 ... wiring pattern, 30, 60 ... bias magnet, 40 ... gear

Claims (7)

At least a pair of magnetic field intensity detection type GMR elements that are identically configured and bridge-connected;
A magnetic field sensor for detecting movement of a magnetic body, comprising a bias magnetic field applying means for applying a bias magnetic field to the pair of GMR elements,
The pair of GMR elements are arranged at a predetermined interval in the same plane, and the bias magnetic field applying means is predetermined in a direction orthogonal to a straight line connecting the centers of the pair of GMR elements in the plane. A magnetic sensor, wherein the magnetic field sensor is arranged so that bias magnetic fields of equal strength in opposite directions and in opposite directions are applied to the pair of GMR elements.   The pair of GMR elements are composed of a linear granular thin film or a linear artificial lattice film formed on an insulating substrate, and the insulating substrate is provided with a plurality of electrodes electrically connected to the pair of GMR elements. The magnetic sensor according to claim 1. The pair of GMR elements, the insulating substrate, and the plurality of electrodes are accommodated in a package molded of resin, and a plurality of conductive lead frames that are electrically connected to the plurality of electrodes protrude from the package. The magnetic sensor according to claim 2. The bias magnetic field applying means is composed of a permanent magnet having a rectangular parallelepiped shape and magnetizing the long first surface to the N pole and the second surface opposite to the first surface to the S pole,
The permanent magnet has a center between two long sides of the first surface or the second surface, the first surface or the second surface being opposed to the pair of GMR elements, and the pair of GMR elements facing the pair of GMR elements. The line is disposed so that a line is inclined by the predetermined angle with respect to a straight line connecting the centers of the pair of GMR elements, and a midpoint of the straight line connecting the centers of the pair of GMR elements is opposed to a point on the center line. The magnetic sensor according to any one of 1 to 3. Applied to the detection of the movement of a magnetic body having at least one convex part or concave part extending in a direction perpendicular to the moving direction;
5. The magnetic sensor according to claim 1, wherein the pair of GMR elements are arranged such that a straight line connecting the centers of the pair of GMR elements is orthogonal to a moving direction of the magnetic body. The pair of GMR elements have shape anisotropy in a longitudinal direction and a short direction, and the pair of GMR elements are arranged so that the longitudinal direction is orthogonal to a straight line connecting the centers of the pair of GMR elements. Item 6. The magnetic sensor according to any one of Items 1 to 5. A first set of GMR elements comprising at least a pair of GMR elements of magnetic field strength detection type that are identically configured and bridge-connected;
A second set of GMR elements comprising at least a pair of magnetic field strength detection type GMR elements, each of which is configured identically to the first set of GMR elements and bridge-connected;
A magnetic sensor comprising bias magnetic field applying means for applying a bias magnetic field to the first pair of GMR elements and the second pair of GMR elements,
The first set of GMR elements are arranged at a predetermined interval in the same plane,
The second pair of GMR elements are spaced apart from each other by a predetermined distance in the plane, and a straight line connecting the centers of the second pair of GMR elements is a straight line connecting the centers of the first pair of GMR elements. And the bias magnetic field applying means includes a straight line connecting the centers of the first pair of GMR elements and the second pair of GMR elements in the plane. The bias magnetic fields having the same strength in opposite directions are inclined with respect to the direction orthogonal to the straight line connecting the centers of the first pair of GMR elements and the second pair of GMR elements. The magnetic sensor is arranged to be applied to each of the magnetic sensors.

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