JP2012233905A - Magnetic sensor and rotation angle detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized magnetic sensor having magnetic isotropy in order to suppress anisotropy of detection sensitivity.SOLUTION: A magnetic sensor uses a spin valve type magneto resistance effect element formed by laminating two ferromagnetic films through a non-magnetic intermediate layer. In the magnetic sensor, a shape of the magneto resistance effect element is a shape linked by a plurality of rings, and each ring is conducted in an electrically connected state, and electric resistance of the magneto resistance effect element is changed to external magnetic field. A rotation angle detection device is constituted of a bridge circuit including at least two detection elements.

Description

  The present invention relates to a magnetic sensor and a rotation angle detection device for detecting a rotating magnetic field.

  A magnetic sensor using a magnetoresistive effect element is useful for realizing non-contact detection, and a magnetic encoder or a magnetic rotation angle sensor is used for the purpose of measuring a rotation angle. In particular, in order to measure the absolute angle, it is important that the detection sensitivity of the magnetoresistive effect element is isotropic with respect to the rotating magnetic field, and that the detection error is small for any magnetic field direction. . For the purpose of realizing such a magnetic rotation angle sensor, for example, Patent Document 1 discloses a spiral magnetoresistive element (helical element) as shown in FIG. In order to distinguish from the reference numerals in the drawings, the reference numerals are indicated in the 100s). This is a technology that configures a spiral element to reduce the magnetic anisotropy due to the shape of the magnetoresistive effect element, that is, the shape magnetic anisotropy, and improves the isotropic property against the rotating magnetic field. . Patent Document 1 discloses a meandering magnetoresistive element (meandering element) as shown in FIG. By using a meandering shape in which semicircular magnetoresistive elements are connected, the magnetic isotropy characteristic of the semicircular arc is to be realized. Patent Document 2 discloses a magnetoresistive effect element in which semicircular shapes are combined as shown in FIG. 12 (in order to distinguish it from the reference numerals in the drawings of the present invention, description of the reference numerals is shown in the 200s).

Japanese Patent No. 3587678 (FIGS. 3 and 4) Japanese Utility Model Publication No. 48-086765 (Fig. 5)

  In the case of the spiral element shown in FIG. 10, the magnitude of the coercive force due to the shape magnetic anisotropy changes depending on the radius of curvature of the spiral, so that there is a difference in detection sensitivity between the central part and the outer peripheral part of the spiral element. As a result, if the area of the pattern of the magnetoresistive effect element is reduced in order to reduce the size of the magnetic sensor, the anisotropy of detection sensitivity becomes significant.

  When the semicircular magnetoresistive effect elements are connected as shown in FIG. 11, the magnetic energy is different with respect to the external magnetic field in the arc portion and the semicircular connection portion, and in the arc portion in the horizontal direction (lateral direction on the paper surface). The magnetic anisotropy is shown, and the semicircular connection portion shows the magnetic anisotropy in the vertical direction (vertical direction on the paper surface). At this time, the number of arc portions and semicircular connection portions constituting the meandering element is always one more in the semicircular connection portion, so that the magnetic anisotropy of the entire magnetoresistive effect element is sufficiently small. It may be insufficient.

  When the end of the arc is connected to the wiring as shown in FIG. 12, the magnetic energy differs with respect to the external magnetic field at the end of the arc and the semicircle, and in the arc (vertical direction on the paper) in the vertical direction. The magnetic anisotropy is shown, and the magnetic anisotropy in the horizontal direction (lateral direction on the paper surface) is shown at the end of the arc. It is difficult to cancel the magnetic anisotropy at the end of the arc.

  In such a situation, in order to sufficiently reduce the shape magnetic anisotropy of the magnetoresistive effect element, it is ideal to use a disk-shaped magnetoresistive effect element (disk type element). However, the disk-type element or the element in which a plurality of the disk-type elements are connected has a problem that the potential distribution inside the disk is not uniform when a current is passed. In addition, in order to obtain a desired electric resistance, the area of the disk-shaped element is increased, and there is a problem that it is contrary to miniaturization.

  The present invention has been made paying attention to such a problem, and provides a small-sized magnetic sensor that suppresses anisotropy of detection sensitivity and has magnetic isotropy, and a rotation angle detection device using the same. It is intended to provide.

  The magnetic sensor of the present invention is a magnetic sensor using a spin valve magnetoresistive effect element in which two ferromagnetic films are laminated via a nonmagnetic intermediate layer, and the shape of the spin valve magnetoresistive effect element is Is a shape in which a plurality of rings are connected, and is energized while the plurality of rings are electrically connected, and the electric resistance of the spin valve magnetoresistive element changes with respect to an external magnetic field. And The ring may have a notch at one place between the portions to be electrically connected (that is, a C-shaped element). Furthermore, the rotation angle detection device of the present invention forms a bridge circuit including at least two spin valve magnetoresistive elements, and detects that the resistance of the bridge circuit changes with respect to the rotating magnetic field. Here, the ferromagnetic film may be either a single layer film or a multilayer film including at least one ferromagnetic layer. One ferromagnetic film is used as a fixed layer whose magnetization direction is fixed during film formation, and the other ferromagnetic film is used as a free layer whose magnetization direction freely rotates along the direction of the rotating magnetic field. The shape in which the rings are connected is a structure in which a plurality of ring-type magnetoresistive elements (hereinafter referred to as ring-type elements) are directly connected, a structure in which a plurality of ring-type elements are integrally formed by batch patterning, or wiring Including a structure in which a plurality of ring-type elements are electrically connected via each other.

  In the present invention, in order to solve the above-mentioned problem, a ring-shaped magnetoresistive element (ring-type element) is manufactured by hollowing out the vicinity of the center of the disk-type element, and a current flowing from one end to the other end of the ring-type element. The width of the flow path (the width of electrical resistance) is made constant. By controlling the width, a desired electric resistance (an electric resistance to be compared when no magnetic field is applied) can be obtained.

  Moreover, in this invention, you may comprise the element for magnetic sensors by connecting a plurality of ring type elements. The arrangement of each ring-type element may be a concentric circuit as shown in FIG. 3, for example. However, since the wiring or terminal for taking out an electric signal from the ring-type elements that are connected while being arranged concentrically requires a three-dimensional arrangement, the ring-type elements are connected as shown in FIG. This is also desirable in order to avoid the complexity of the laminated structure for obtaining the magnetic sensor and to reduce the manufacturing cost.

  In addition, it can be set as the shape (C-shaped element) which notched a part of ring type element. However, it is assumed that the C-shaped element is notched at a position where it does not overlap with a wiring or a terminal through which a current flows. Desirably, a notch is provided at a position shifted by about 90 ° in the circumferential direction of the ring from the position of the wiring or terminal. Furthermore, a plurality of C-shaped elements can be connected to form a magnetic sensor element.

  ADVANTAGE OF THE INVENTION According to this invention, the anisotropy of a detection sensitivity can be suppressed and a magnetic sensor with a magnetic isotropy and a small magnetic sensor and a rotation angle detection apparatus using the same can be provided.

  Hereinafter, the present invention will be described using more specific embodiments. However, the present invention is not limited by these embodiments. Similar parts will be described with the same reference numerals.

FIG. 1 is a plan view of a magnetoresistive effect element according to an embodiment of the present invention. The three ring-type elements 1a, 1b, and 1c are all spin-valve type magnetoresistive effect elements, and constitute a ring-type element 1A that is electrically connected by forming the ends of each other while being arranged on a straight line. did. The same structure is formed, and “connected ring-shaped elements 1B, 1C, and 1D” whose longitudinal directions are inclined 90 °, 180 °, and 270 ° clockwise are formed and connected by wiring to form a Wheatstone bridge. I was able to. A further developed configuration is shown in FIG. FIG. 2 is a plan view of the magnetic sensor 9 according to the embodiment of the present invention, in which a first bridge circuit and a second bridge circuit are formed on the substrate 4. In the first bridge circuit, the connected ring-type elements 1A, 1B, 1C and 1D constitute a Wheatstone bridge, the terminal 3e is Vcc, the terminal 3f is Gnd, and the terminals 3a and 3j are connected between the terminals 3a and 3j. An output voltage Vo1 is obtained. The second bridge circuit forms a Wheatstone bridge with the connected ring-type elements 1E, 1F, 1G and 1H, the terminal 3c is Vcc, the terminal 3h is Gnd, the terminals 3b and 3g and the terminals 3d and 3i. Output voltage Vo2 is obtained. The pinned layer magnetization direction of the spin-valve magnetoresistive element constituting each ring type element is indicated by a thick arrow. Since the second bridge circuit rotates the fixed layer magnetization direction by 90 ° with respect to the first bridge circuit, when a rotating magnetic field changing sinusoidally is applied in a direction parallel to the substrate, the output voltages Vo1 and Vo2 are The rotation angle θ can be obtained by performing an arctangent (tan ⁻¹ θ) calculation in a relationship between a cosine wave and a sine wave.

FIG. 3 is a plan view of another magnetoresistive element according to the embodiment of the present invention. In FIG. 3A, three ring-type elements 11a, 11b and 11c having different outer diameters and the same line width are arranged concentrically, and a Cu electrode film is connected as a wiring. Wiring 12a → ring element 11a → wiring 12b → ring element 11b → wiring 12c → ring element 11c → junction 12d ₂ → wiring 12d (Since it overlaps with other members, it is displayed as a dotted line for easy understanding. ) Each ring-type element has an annular shape, and an element having magnetic isotropy with respect to a rotating magnetic field was obtained. In FIG. 3B, in the configuration of FIG. 3A, a C-shaped element is formed by further forming a notch in the ring type element one by one. Looking at the C-shaped element 13b, the current flows from the wiring 12b, flows through the semicircular portion of the C-shaped element 13b on the side without the notch 14, and flows out of the wiring 12c. That is, in the C-shaped element, the magnetic active portion and the electrical path are different. Since notches are not formed in the vicinity of the junction between the wirings 12b and 12c and the C-shaped element (since the notch 14 and the junction are separated), the C-shaped element is magnetic in the vicinity of the junction. The shape anisotropy of the notch 14 can be reduced to the extent that the output voltage is distorted (the configuration (a) that can obtain magnetic isotropy has a problem with the output voltage). There is no distortion that would occur.) On the other hand, when the end of the semicircle of the magnetoresistive element is connected to the wiring as in the conventional example of FIG. 12, the magnetic anisotropy at the end of the semicircle causes distortion that cannot be ignored in the output voltage. The problem of making it happened. In FIG. 3B, since current flows through the semicircular portion of each C-shaped element without a cutout (current does not flow through the semicircular portion of the cutout side), the magnetic sensor The output of can be increased. With respect to the structure of the connected ring type element 1A shown in FIG. 1 as well, when a notch was formed in one of the semicircular portions, the same function as in FIG. 12B could be obtained.

  FIG. 4 is a plan view of another magnetoresistive element according to the embodiment of the present invention. FIG. 4A shows a magnetic sensor 29 in which a terminal unit 23, a ring-type element 23 formed in one body, and a terminal unit 23 are connected to a substrate 24. The portion where the three ring-type elements were connected was obtained by forming a spin valve magnetoresistive effect element into a film and then patterning it into a shape corresponding to the three rings. The pair of terminal portions 23 is composed of a Cu film. In FIG. 4B, three ring-type elements 31a, 31b and 31c made of spin-valve magnetoresistive elements are formed on the substrate 34, and a pair of terminals 33 are also formed. The magnetic sensor 39 is electrically connected by forming wirings 32a, 32b, 32c and 32d therebetween.

  FIG. 5 is a plan view of another magnetic sensor 49 according to the embodiment of the present invention. In the circuit shown in FIG. 5, the ring-type elements 41a and 41b connected on the substrate 44 are connected to the ring-shaped elements 41a and 41b (the terminals 41a and 41b are connected via the connection terminals represented by triple circles and arranged in a V shape). 41g and 41h have a small electric resistance with respect to the upward magnetic field in the figure, and the ring-type elements 41e and 41f connected with the connected ring-type elements 41c and 41d have a small electric resistance with respect to the downward magnetic field in the figure. It is a structure that is built into the Wheatstone bridge. All of the three ring-type elements constituting the linked ring-type elements are spin-valve magnetoresistive effect elements, and are electrically connected by forming the ends of each other while being arranged on a straight line. The pinned layer magnetization direction of the spin-valve magnetoresistive element constituting the coupled ring elements 41a and 41b is indicated by a thick upward arrow. Each linked ring element has three ring elements connected in a straight line. However, as shown in FIGS. 8 and 9, a curved arrangement may be used. However, in order to prevent the occurrence of anisotropy due to the element arrangement, it is necessary to arrange the magnetic circuit composed of the ring type element on the object to be rotated. The wiring of the magnetic sensor in FIG. 9 is the same as that in FIG.

FIG. 6 is a circuit diagram illustrating a bridge circuit in the magnetic sensor of FIG. The first bridge circuit and the second bridge circuit are formed on the substrate 44. In the first bridge circuit, the connected ring-type elements 41a and 41b, 41c and 41d, 41e and 41f, 41g and 41h constitute a Wheatstone bridge, the terminal 43e is Vcc, the terminal 43f is Gnd, and the terminal The output voltage Vo1 is obtained between the terminal 43a and the terminal 43j. In the second bridge circuit, the connected ring-type elements 41i and 41j, 41k and 41l, 41m and 41n, 41o and 41p form a Wheatstone bridge, the terminal 43c is Vcc, the terminal 43h is Gnd, and the terminal An output voltage Vo2 is obtained between 43b and 43g and terminals 43d and 43i. The pinned layer magnetization direction of the spin-valve magnetoresistive element constituting each ring type element is indicated by a thick arrow. Since the second bridge circuit rotates the fixed layer magnetization direction by 90 ° with respect to the first bridge circuit, when a rotating magnetic field changing sinusoidally is applied in a direction parallel to the substrate, the output voltages Vo1 and Vo2 are The rotation angle θ can be obtained by performing an arctangent (tan ⁻¹ θ) calculation in a relationship between a cosine wave and a sine wave. As another embodiment, when the upper bridge circuit in FIG. 6 is a half bridge in which ring-shaped elements connected on two sides are replaced with normal electrical resistance, the lower bridge circuit in FIG. However, a half bridge in which the ring-shaped elements connected on the two sides are replaced with ordinary electric resistances is used.

  FIG. 7A is a plan view of a sensor device using the magnetic sensor of FIG. 6, and FIG. 7B is a schematic view of a rotation angle detection apparatus using the sensor device. The sensor device 59 is configured by providing a magnetic sensor 49 on a lead frame, electrically connecting the terminals of the magnetic sensor 49 and electrode pins 52 with bonding wires 53, and covering with a mold resin 51. The sensor device 59 was disposed so as to face the disk-shaped permanent magnet 56 magnetized in the radial NS2 pole. The disk-shaped permanent magnet 56 is connected to the rotating shaft 54 via the magnet support portion 55, and when the rotating shaft rotates, the component parallel to the xy plane of the magnetic force lines 57 applied to the sensor device 59 also becomes the rotating shaft. Rotate in the same way. This rotating magnetic field was detected by the sensor device 59.

It is a top view of the magnetoresistive effect element concerning the embodiment of the present invention. It is a top view of the magnetic sensor which concerns on embodiment of this invention. It is a top view of the other magnetoresistive effect element based on embodiment of this invention. It is a top view of the other magnetoresistive effect element based on embodiment of this invention. It is a top view of the other magnetic sensor which concerns on embodiment of this invention. It is a circuit diagram explaining the bridge circuit in the magnetic sensor of FIG. (A) The top view of the sensor device using the magnetic sensor of FIG. 6, (b) It is the schematic of the rotation angle detection apparatus using the said sensor device. It is a top view of the other magnetoresistive effect element based on embodiment of this invention. It is a top view of the other magnetic sensor which concerns on embodiment of this invention. It is a top view of the conventional magnetic sensor. It is a top view of the other conventional magnetic sensor. It is a top view of the other conventional magnetic sensor.

1a, 1b, 1c: ring type element, 1A: linked ring type element,
1d, 1e, 1f: ring type element, 1B: linked ring type element,
1g, 1h, 1i: ring type element, 1C: linked ring type element,
1j, 1k, 11: ring type elements, 1D: linked ring type elements,
1E, 1F, 1G, 1H: connected ring type elements,
3a, 3b, 3c, 3d, 3e: terminals,
3f, 3g, 3h, 3i, 3j: terminals,
4: substrate, 9: magnetic sensor,
11a: inner ring type element, 11b: middle ring type element,
11c: outer ring-shaped element,
12a, 12b, 12c, 12d: wiring (electrode film), 12d ₂ : junction,
13a: inner C-shaped element, 13b: middle C-shaped element,
13c: outer C-shaped element, 14: notch,
21: ring-shaped element formed integrally, 23: terminal portion, 24: substrate, 29: magnetic sensor,
31a, 31b, 31c: ring type elements,
32a, 32b, 32c, 32d: wiring,
33: terminal, 34: substrate, 39: magnetic sensor,
41a, 41b: connected ring type elements, 41c, 41d: connected ring type elements,
41e, 41f: connected ring type elements, 41g, 41h: connected ring type elements,
41i, 41j: connected ring elements, 41k, 41l: connected ring elements,
41m, 41n: connected ring type elements, 41o, 41p: connected ring type elements,
_{42e 1, 42e 2, 42f 1} , 42f 2: wiring,
43a, 43b, 43c, 43d, 43e: terminals,
43f, 43g, 43h, 43i, 43j: terminals,
44: substrate, 49: magnetic sensor,
51: Mold resin, 52: Electrode pin, 53: Bonding wire, 54: Rotating shaft,
55: Magnet support part, 56: Disk-shaped permanent magnet, 57: Magnetic field line, 59: Sensor device,
61A, 61B, 61C, 61D: connected ring type elements,
61E, 61F, 61G, 61H: connected ring type elements,
63a, 63b, 63c, 63d, 63e: terminals,
63f, 63g, 63h, 63i, 63j: terminal, 69: substrate,
103: Magnetic field sensor 108: Substrate 130: Magnetoresistive film
130a, 130b: both ends of a spiral shape pattern,
131: Pattern shape of magnetoresistive effect film, 137: Insulating film,
191, 195, 191a, 195a: conductor electrode film,
104: Magnetic field sensor, 140: Magnetoresistive film,
141: pattern shape of magnetoresistive effect film, 141a: substantially semicircular shape,
201: magnetoresistive effect element, 201A: element body part, 201B: auxiliary element part,
202: Metal bar, 203: Rotating yoke,
213, 221, 222, 223, 224, 225: terminals,

Claims (3)

A magnetic sensor comprising a Wheatstone bridge circuit using a spin-valve magnetoresistive element in which two ferromagnetic films are laminated via a nonmagnetic intermediate layer,
The spin valve magnetoresistive element has a shape in which a plurality of cutout C-shaped elements are connected,
The C-shaped element, and one have a notch 90 ° shifted position in the circumferential direction of the ring from the position of the C-shaped element or pin of an adjacent,
The magnetic sensor according to claim 1, wherein the notch is separated from a joint portion between adjacent C-shaped elements or terminals . The shape in which a plurality of the C-shaped elements are connected is a concentric arrangement of the C-shaped elements ,
The magnetic sensor according to claim 1, wherein the C-shaped element has one notch at a position shifted by 180 ° in the circumferential direction of the ring from the position of the notch of the adjacent C-shaped element .   A rotation angle detection apparatus comprising the magnetic sensor according to claim 1.

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