JP2022148862A - Magnetic sensor device - Google Patents

Abstract

To enhance sensitivity of a magnetic sensor device equipped with a magnetic sensor configured to sense magnetic fields by means of the magnetic impedance effect.SOLUTION: A magnetic sensor device 1 is provided, comprising a magnetic sensor 10 configured to sense magnetic fields by means of the magnetic impedance effect, and a detection unit 300 configured to detect change in impedance of the magnetic sensor 10, where area of a current loop formed by wiring near the magnetic sensor 10 is smaller than that of a current loop formed by wiring near the detection unit 300.SELECTED DRAWING: Figure 1

Description

The present invention relates to a magnetic sensor device.

As a prior art disclosed in the publication, a magneto-impedance element comprising a substrate made of a non-magnetic material and a thin-film magnetic core formed on the substrate and provided with electrodes at both ends in the longitudinal direction, the thin-film magnetic core has at least two magnetic cores. There is a magneto-impedance element characterized in that more than one magnetic core is arranged in parallel and the respective thin-film magnetic cores are electrically connected in series (see Patent Document 1).

JP-A-2000-292506

In a magnetic sensor device having a magnetic sensor that senses a magnetic field by the magneto-impedance effect, changes in impedance are detected by a detector and converted into magnetic field intensity. However, since the wiring that connects the magnetic sensor and the detection unit also has impedance, if the impedance of the wiring is high, the rate of change in impedance due to the magnetic field will be small, resulting in a decrease in sensitivity.
SUMMARY OF THE INVENTION An object of the present invention is to improve the sensitivity of a magnetic sensor device having a magnetic sensor that senses a magnetic field by the magneto-impedance effect.

A magnetic sensor device to which the present invention is applied includes a magnetic sensor that senses a magnetic field by the magneto-impedance effect and a detection unit that detects changes in the impedance of the magnetic sensor. is smaller than the current loop formed by wiring near the detector.
Such a magnetic sensor device can be characterized in that the inductance caused by the current loop formed by the wiring near the magnetic sensor and the current loop formed by the wiring near the detection unit is 50% or less of the inductance of the magnetic sensor. .

The magnetic sensor in such a magnetic sensor device comprises a non-magnetic substrate, a sensing circuit provided on the surface of the substrate and including a sensing portion that senses a magnetic field by the magneto-impedance effect, and is connected to both ends of the sensing circuit. a first terminal portion, a second terminal portion, and a conductive folded member whose one end portion is connected to the first terminal portion and folded back toward the second terminal portion side; can do.
Further, the folding member in the magnetic sensor can be characterized by being a wiring made of a non-magnetic metal.
Further, a third terminal portion provided adjacent to the second terminal portion of the magnetic sensor is provided, and the other end portion of the folded member is connected to the third terminal portion. can.
Further, the distance between the centers of the second terminal portion and the third terminal portion of the magnetic sensor is smaller than the distance between the centers of the first terminal portion and the second terminal portion of the magnetic sensor. can be characterized by
Furthermore, the folding member in the magnetic sensor can be characterized by being provided on the surface side or the back surface side of the substrate.

The magnetic sensor in such a magnetic sensor device comprises a first sensing circuit including a sensing portion that senses a magnetic field by the magnetoimpedance effect, and a second sensing circuit that includes a sensing portion that senses the magnetic field by the magnetoimpedance effect, At least part of the current paths of the first sensing circuit and the second sensing circuit overlap in plan view, and one ends of the respective current paths are electrically connected to each other.
Further, the first sensing circuit and the second sensing circuit in the magnetic sensor can be characterized in that the directions of the currents in the overlapping and facing portions are opposite to each other.

A magnetic sensor in such a magnetic sensor device includes a sensing circuit including a sensing portion that senses a magnetic field by the magneto-impedance effect, and a current circuit made of a non-magnetic conductor. , at least a part of the current paths overlap in a plan view, and one ends thereof are electrically connected to each other.

According to the present invention, the sensitivity of a magnetic sensor device having a magnetic sensor that senses a magnetic field by the magneto-impedance effect is improved.

It is a figure explaining the magnetic sensor apparatus with which 1st Embodiment is applied. (a) is a magnetic sensor device to which the first embodiment is applied, and (b) is a magnetic sensor device to which the first embodiment is not applied, shown for comparison. 1B is a diagram showing the relationship between the area of a current loop formed by wiring near the magnetic sensor and the inductance in the magnetic sensor shown in FIG. 1B; FIG. It is a figure explaining an example of the magnetic sensor to which 1st Embodiment is applied. (a) is a plan view, and (b) is a sectional view taken along line IIIB-IIIB of (a). 4 is a diagram for explaining the relationship between the magnetic field applied in the longitudinal direction of the sensing portion of the magnetic sensor and the impedance of the magnetic sensor 10. FIG. It is a figure which explains three-dimensionally the magnetic sensor to which 1st Embodiment is applied. (a) is a perspective view, and (b) is a side view of the magnetic sensor of (a) viewed from the x-direction side. (a) to (d) are diagrams showing variations of the magnetic sensor to which the first embodiment is applied. 8A to 8C are diagrams showing other variations of the magnetic sensor to which the first embodiment is applied; FIG. It is a figure explaining the sensitivity in a magnetic sensor. (a) is the relationship between the area of the current loop and the sensitivity, and (b) is the relationship between the distance between the magnetic sensor and the wiring and the sensitivity. FIG. 4 is a diagram showing the sensitivity of variations of the magnetic sensor; (a) is the sensitivity measured with two samples having the same structure, and FIG. 9(b) is the sensitivity measured with two samples having different structures. It is a figure explaining other magnetic sensors to which a 1st embodiment is applied. (a) is a perspective view, and (b) is a side view of the magnetic sensor of (a) viewed from the x direction. It is a figure explaining the magnetic sensor to which 2nd Embodiment is applied. (a) is a perspective view, and (b) is a side view of the magnetic sensor of (a) viewed from the x direction. (a) to (c) are diagrams showing variations of the magnetic sensor to which the second embodiment is applied. It is a figure which shows the variation of the magnetic sensor to which 3rd Embodiment is applied. It is a figure explaining the magnetic sensor apparatus with which 4th Embodiment is applied. It is a top view explaining an example of a sensing circuit. It is a figure explaining the structure of a magnetic sensor. (a) is a perspective view of a magnetic sensor, and (b) is a diagram for explaining currents and magnetic fields in two sensing circuits. It is a figure explaining how to overlap two sensing circuits in a magnetic sensor. (a) is an arrangement in which two sensing circuits are opposed inside, (b) is an arrangement in which two sensing circuits are opposed outside, and (c) is an arrangement in which two sensing circuits are stacked. , (d) is an arrangement in which two sensing circuits are provided on the front and back sides of one substrate. It is a figure explaining the sensitivity in the magnetic sensor apparatus using the magnetic sensor which superimposed two sensing circuits. (a) is the relationship between the area of the current loop and the sensitivity, and (b) is the relationship between the distance between the two sensing circuits and the sensitivity. Fig. 3 shows the sensitivity of a magnetic sensor device comprising a magnetic sensor with two superimposed sensitive circuits; It is a figure explaining the structure of the magnetic sensor in the magnetic sensor apparatus to which 5th Embodiment is applied. (a) is a perspective view of a magnetic sensor, and (b) is a diagram for explaining currents and magnetic fields in a sensing circuit and a current circuit.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[First embodiment]
(Magnetic sensor device 1)
FIG. 1 is a diagram illustrating a magnetic sensor device 1 to which the first embodiment is applied. FIG. 1(a) is a magnetic sensor device 1 to which the first embodiment is applied, and FIG. 1(b) is a magnetic sensor device 1' to which the first embodiment is not applied, shown for comparison. be. When the magnetic sensor device is not distinguished, it is written as a magnetic sensor device.

As shown in FIG. 1(a), a magnetic sensor device 1 to which the first embodiment is applied includes a magnetic sensor 10 that senses a magnetic field, an alternating current generator 200, and a detector 300. . The magnetic sensor 10 is connected to an alternating current generator 200 and a detector 300 via connection terminals 20 and 30 . The magnetic sensor 10 has a sensing portion 121 (see FIG. 3A, which will be described later) whose impedance changes with changes in the magnetic field based on the magneto-impedance effect.

The alternating current generator 200 includes a circuit that generates a current containing high frequency components (hereinafter referred to as high frequency current), and supplies the high frequency current to the magnetic sensor 10 . In addition, a high frequency is 20 MHz or more, for example.
The detection unit 300 includes a circuit that detects changes in impedance of the magnetic sensor 10 . Specifically, the detection unit 300 detects changes in the inductance of the magnetic sensor 10 and changes in the amplitude and phase of the impedance.

FIG. 1A shows a current loop α formed between the magnetic sensor 10 and the connection terminals 20 and 30, and a current loop β formed between the connection terminals 20 and 30 and the detection unit 300. showing. The current loop α is a current loop formed by wiring near the magnetic sensor 10 , and the current loop β is a current loop formed by wiring near the detection unit 300 . Hereinafter, the current loop α is referred to as the current loop α formed by the wiring near the magnetic sensor 10, and the current loop β is referred to as the current loop β formed by the wiring near the detection unit 300. A current loop including the current loop α and the current loop β is a current loop surrounded by the magnetic sensor 10 and the detection unit 300 . A current loop acts as an inductance. The larger the area of the current loop, the larger the inductance.

A current loop α formed by wiring near the magnetic sensor 10 is composed of a current loop α1 in the magnetic sensor 10 and a current loop α2 between the magnetic sensor 10 and the connection terminals 20 and 30 . Therefore, in FIG. 1A, the current loops α1(α) and α2(α) are indicated.

As shown in FIG. 1B, the magnetic sensor device 1' to which the first embodiment is not applied is shown in FIG. It is the same as the magnetic sensor device 1 to which the first embodiment is applied. Therefore, the same reference numerals are assigned to the same parts, and the description thereof is omitted. The current loop α' formed by the wiring near the magnetic sensor 10' has a larger area than the current loop α formed by the wiring near the magnetic sensor 10 shown in FIG. 1(a). The current loop α' is composed of a current loop α'1 in the magnetic sensor 10' and a current loop α'2 between the magnetic sensor 10' and the connection terminals 20 and 30. FIG. Therefore, in FIG. 1(b), current loops α'1(α') and current loops α'2(α') are indicated.

The area of the current loop α'1 in the magnetic sensor 10' shown in FIG. 1(b) is not much different from the area of the current loop α1 in the magnetic sensor 10 shown in FIG. 1(a). Therefore, the area of the current loop α′ formed by the wiring near the magnetic sensor 10′ is larger than the area of the current loop α formed by the wiring near the magnetic sensor 10 because the magnetic sensor 10′ and the connection terminals 20, 30 This is because the area of the current loop α'2 at is larger than that of the current loop α2.
Note that when the magnetic sensor 10 and the magnetic sensor 10' are not distinguished from each other, they may be referred to as a magnetic sensor. If the current loops α, α', and β are not distinguished, they may be referred to as current loops. Terminal portions 13a, 13b, and 13c shown in FIGS. 1(a) and 1(b) will be described later with reference to FIG. 3(a).

Here, the influence of the inductance due to the current loop on the inductance change of the magnetic sensor device 1 will be described. Note that the magnetic sensor device 1 shown in FIG. 1A will be described as an example.
Let L1 be the inductance of the magnetic sensor 10 when no signal magnetic field is applied, and let ΔL1 be the amount of change in the inductance of the magnetic sensor 10 when the signal magnetic field is applied. Let L2 be the inductance generated by the current loop α formed by the wiring near the magnetic sensor 10 and the current loop β formed by the wiring near the detection unit 300 . A signal magnetic field is a magnetic field applied to the magnetic sensor 10 from the outside in order to explain the operation of the magnetic sensor 10 . When a signal magnetic field is applied to the magnetic sensor 10, the impedance of the magnetic sensor 10 changes compared to when no signal magnetic field is applied.

The inductance when no signal magnetic field is applied is L1+L2. The inductance in the state where the signal magnetic field is applied is L1+ΔL1+L2. Therefore, the rate of change of the inductance detected by the detection unit 300 is (L1+ΔL1+L2)/(L1+L2) due to the application of the signal magnetic field. Therefore, the inductance change rate increases as the inductance L2 decreases. In other words, the smaller the inductance L2, the larger the rate of change of the inductance and the higher the sensitivity of detecting the magnetic field. That is, the sensitivity of the magnetic sensor 10 is improved by reducing the inductance L2 caused by the current loop α formed by the wiring near the magnetic sensor 10 and the current loop β formed by the wiring near the detection unit 300 .

FIG. 2 shows the relationship between the area of the current loop α' formed by the wiring near the magnetic sensor 10' and the inductance generated by the magnetic sensor 10' and the current loop α' in the magnetic sensor 10' shown in FIG. 1(b). FIG. 4 is a diagram showing; The horizontal axis is the area of the current loop α' (current loop area (mm ² ) in FIG. 2), and the vertical axis is the inductance (nH). Here, the inductance was measured by connecting the terminal portion 13a and the terminal portion 13b of the magnetic sensor 10 shown in FIG. 3, which will be described later, to an impedance measuring instrument. At this time, the area surrounded by the wires connecting the terminal portions 13a and 13b and the impedance measuring device was changed. In FIG. 2, the frequencies for measuring the inductance are 20 MHz, 50 MHz and 100 MHz.

As shown in FIG. 2, the inductance caused by the magnetic sensor 10' and the current loop α' increases as the area of the current loop α' increases. Also, the inductance caused by the magnetic sensor 10' and the current loop α' increases as the frequency increases. In other words, the inductance can be reduced by reducing the area of the current loop α'. In FIG. 2, the area of the current loop α' is explained. You can think of it as harmony. In the following description, the area of the current loop α' is referred to as the area of the current loop.

Here, the inductance (corresponding to L1) of the magnetic sensor 10 corresponding to a current loop area of 0 mm ² is approximately 85 nH. As shown in FIG. 2, the inductance (corresponding to L1+L2) when the current loop area is 16 mm ² is 101 nH as an average value for the frequencies of 20 MHz, 50 MHz, and 100 MHz, which is 1 of the inductance of the magnetic sensor 10. .2 times. Also, the inductance (corresponding to L1+L2) when the area of the current loop is 47 mm ² is a similar average value of 116 nH, which is 1.4 times the inductance of the magnetic sensor 10 . As will be described later with reference to FIGS. 8 and 18, the area of the current loop is preferably 50 mm ² or less, more preferably 16 mm ² or less. The inductance L2 is preferably 50% or less of the inductance L1, more preferably 20% or less.

Note that the detection unit 300 may detect changes in impedance including the inductance L, the resistance R, and the capacitance C instead of detecting changes in the inductance of the magnetic sensor 10 described above. For example, the detection section 300 may include a circuit that detects the amplitude and phase of impedance. In this case, the impedance Z is written as Z=R+jωL+1/(jωC)=R+jX. Then, the amplitude |Z| is |Z|=√(R ² +X ² ), and the phase θ is written as θ=tan ⁻¹ (X/R). where ω is the angular frequency and X is the reactance.

The area of the magnetic sensor 10' (corresponding to the magnetic sensor 10 shown in FIG. 3A, which will be described later) tends to be larger than the electronic components forming the alternating current generating section 200 and the detecting section 300. FIG. Therefore, as shown in FIG. 1B, the area of the current loop α' formed by the wiring near the magnetic sensor 10' tends to be larger than the area of the current loop β formed by the wiring near the detection unit 300. FIG. Therefore, it is preferable to reduce the current loop α' formed by the wiring near the magnetic sensor 10'. However, since the current loop α'1 in the magnetic sensor 10' is determined by the shape of the magnetic sensor 10', it is difficult to reduce the area of the current loop α'1 in the magnetic sensor 10'. Also, the area of the current loop α'2 between the magnetic sensor 10 and the connection terminals 20 and 30 tends to be larger than the area of the current loop α'1 in the magnetic sensor 10'.

Therefore, in the magnetic sensor device 1 (FIG. 1(a)) to which the first embodiment is applied, the area of the current loop α2 between the magnetic sensor 10 and the connection terminals 20 and 30 is equal to that of the first embodiment. It is made smaller than the area of the current loop α'2 between the magnetic sensor 10' and the connection terminals 20, 30 in the magnetic sensor device 1' (FIG. 1(b)) to which the configuration is not applied.

(Magnetic sensor 10)
Here, the magnetic sensor 10 included in the magnetic sensor device 1 to which the first embodiment is applied will be described.
FIG. 3 is a diagram illustrating an example of the magnetic sensor 10 included in the magnetic sensor device 1 to which the first embodiment is applied. 3(a) is a plan view, and FIG. 3(b) is a cross-sectional view taken along line IIIB-IIIB of FIG. 3(a). In FIG. 3A, the right direction on the paper surface is the +x direction, the upward direction on the paper surface is the +y direction, and the surface direction on the paper surface is the +z direction. In FIG. 3B, the right direction on the paper is the +x direction, the upward direction on the paper is the +z direction, and the back direction on the paper is the +y direction.

The planar structure of the magnetic sensor 10 will be described with reference to the plan view of FIG. 3(a). The magnetic sensor 10 has, for example, a rectangular planar shape. The planar shape of the magnetic sensor 10 is several millimeters square to several tens of millimeters square. For example, the length in the x direction is 3 mm to 20 mm, and the length in the y direction is 3 mm to 20 mm. Note that the size of the planar shape of the magnetic sensor 10 may be another value.

The magnetic sensor 10 includes a substrate 11 , a sensing circuit 12 provided on the substrate 11 , terminal portions 13 a , 13 b and 13 c , and turn-back wiring 14 . The sensing circuit 12 includes a plurality of sensing portions 121 arranged in parallel, and a connection portion 122 connecting the sensing portions 121 in series in a meandering structure. The terminal portions 13 a and 13 b are provided at one end and the other end of the sensing circuit 12 . The terminal portion 13c is provided on the substrate 11 so as to be adjacent to the terminal portion 13b. The turn-back wiring 14 is provided so as to extend along the back side of the substrate 11, and connects the terminal portion 13a and the terminal portion 13c. In addition, in FIG. 3A, the folded wiring 14 hidden behind the back surface of the substrate 11 is indicated by a broken line. Here, the terminal portion 13a is an example of a first terminal portion, the terminal portion 13b is an example of a second terminal portion, the terminal portion 13c is an example of a third terminal portion, and the folded wiring 14 is an example of a folded member. .

The sensing portion 121 has a strip-like planar shape having a longitudinal direction and a lateral direction. The sensing part 121 shown in FIG. 3A has a longitudinal direction in the x direction and a lateral direction in the y direction. In FIG. 3A, four sensing parts 121 are arranged in parallel in the y direction. The sensitive part 121 exhibits the magneto-impedance effect. Therefore, the magnetic sensor 10 or sensing circuit 12 may be referred to as a magneto-impedance element. And the sensing part 121 may be described as a sensing element.

Each sensing part 121 has a longitudinal length of 1 mm to 10 mm and a lateral width of 50 μm to 150 μm, for example. The thickness is 0.2 μm to 5 μm. The interval between adjacent sensitive parts 121 is 50 μm to 150 μm. Although the number of sensing parts 121 is four in FIG. 3(a), it may be another number.
The size (length, area, thickness, etc.) of each sensing part 121, the number of sensing parts 121, the spacing between the sensing parts 121, etc. are set according to the magnitude of the magnetic field to be sensed, that is, to be detected. Just do it. In addition, the number of the sensing parts 121 may be one.

The connecting portion 122 is provided between the ends of adjacent sensing portions 121 and connects the plurality of sensing portions 121 in series. In other words, the connecting portion 122 is provided so as to connect the adjacent sensing portions 121 in a zigzag manner. The magnetic sensor 10 having four sensing portions 121 shown in FIG. 3A has three connecting portions 122 . The number of connecting portions 122 varies depending on the number of sensing portions 121 . For example, if the number of sensing parts 121 is five, the number of connection parts 122 is four. Moreover, if the number of sensing parts 121 is one, the connection part 122 is not provided. The width of the connecting portion 122 may be set according to the current flowing through the sensing circuit 12 or the like. For example, the width of the connecting portion 122 may be the same as that of the sensing portion 121 .

The terminal portions 13 a and 13 b are provided at one end and the other end of the sensing circuit 12 . In FIG. 3A, the terminal portion 13a is provided on the upper side (y-direction side) of the paper, and the terminal portion 13b is provided on the lower side (-y-direction side) of the paper. A terminal portion 13c is provided below the terminal portion 13b (on the -y direction side). When the terminal portions 13a, 13b, and 13c are not distinguished from each other, they are referred to as a terminal portion 13. FIG. The terminal portion 13 may have any size as long as it can be connected to a circuit. Since the magnetic sensor 10 shown in FIG. 3A has four sensing portions 121, the terminal portions 13a and 13b are provided on the right side (x direction side) of the paper surface. When the number of sensing portions 121 is an odd number, the terminal portions 13a and 13b are provided separately on the left and right sides (±x direction sides) of the paper surface. It should be noted that the sensing circuit 12 may be configured by horizontally reversing it.

Terminal portion 13c is provided adjacent to terminal portion 13b. Here, the terminal portion 13c is provided adjacent to the terminal portion 13b in the -y direction. Then, the folded wiring 14 connects the terminal portion 13a and the terminal portion 13c. In other words, the folded wiring 14 is a wiring that pulls out the terminal portion 13a to a position (terminal portion 13c) adjacent to the terminal portion 13b. In other words, the turn-back wiring 14 is conductive, and provided so as to turn back a path through which current flows from the terminal portion 13a to the terminal portion 13b (hereinafter referred to as a current path). Examples of the conductive material forming the turn-back wiring 14 include metals such as Au, Al, Cu, and Ag.

The terminal portions 13b and 13c of the magnetic sensor 10 are connected to the connection terminals 20 and 30 of the alternating current generating portion 200 and the detecting portion 300, respectively. That is, a high-frequency current is supplied from the alternating current generator 200 through the terminals 13b and 13c, and the detector 300 detects changes in inductance, amplitude and phase of impedance, and the like.

Here, the magnetic sensor 10' shown in FIG. 1(b) does not include the terminal portion 13c and the folded wiring 14 in the magnetic sensor 10 shown in FIG. 3(a). Therefore, as shown in FIG. 1(b), in the magnetic sensor 10′, the connection between the terminal portion 13a and the terminal portion 13b located away from the terminal portion 13a, the AC current generating portion 200 and the detecting portion 300 is Terminals 20 and 30 are connected. On the other hand, the magnetic sensor 10 shown in FIG. 1A is provided with a terminal portion 13c adjacent to the terminal portion 13b, and the folded wiring 14 passes near the sensing circuit 12 to connect the terminal portion 13a and the terminal portion 13c. to connect. Then, the terminal portion 13b and the terminal portion 13c adjacent to the terminal portion 13b are connected to the connection terminals 20 and 30 for the AC current generating portion 200 and the detecting portion 300, respectively. Therefore, the area of the current loop α'2 between the magnetic sensor 10' and the connection terminals 20, 30 shown in FIG. 30 is larger than the area of the current loop α2. That is, the magnetic sensor 10 included in the magnetic sensor device 1 to which the first embodiment is applied has the terminal portion 13c and the turn-back wiring 14, thereby reducing the area of the current loop α2. Here, D1 shown in FIG. 3A is the center-to-center distance between the terminal portions 13b and 13c, and D2 is the center-to-center distance between the terminal portions 13a and 13b. Note that even when the terminal portions 13a and 13b are provided at diagonal positions of the magnetic sensor 10 (see FIG. 7A described later), the distance D2 is It is the distance between the centers of 13a and terminal portion 13b.

In FIG. 3A, the terminal portion 13c is provided below the terminal portion 13b (on the −y direction side), but the terminal portion 13c may be provided adjacent to the terminal portion 13b. That is, the distance D1 between the terminal portion 13b and the terminal portion 13c should be set shorter than the distance D2 between the terminal portion 13a and the terminal portion 13b (D1<D2). Therefore, the terminal portion 13c may be provided adjacent to the terminal portion 13b on the x direction side or the −x direction side, and may be provided diagonally above the terminal portion 13b (±x direction +y direction side) or diagonally below (±x direction side). direction (y direction side).
The folded wiring 14 will be described in detail later.

As described above, the sensing circuit 12 is configured such that the sensing portions 121 are connected in series by the connecting portions 122 in a zigzag manner, and a high-frequency current flows from the terminal portions 13a and 13b provided at both ends. Therefore, since it is a path through which a high-frequency current flows, it is referred to as a sensing circuit 12 .

The cross-sectional structure of the magnetic sensor 10 will be described with reference to the cross-sectional view of FIG. 3(b). Here, description of the turn-back wiring 14 is omitted, and the structure of the sensing circuit 12 will be mainly described.
The magnetic sensor 10 includes a substrate 11 and a sensing circuit 12 provided on the substrate 11, as described above. As an example, the sensing circuit 12 includes four soft magnetic layers 111a, 111b, 111c, and 111d from the substrate 11 side. The sensing circuit 12 includes a magnetic domain suppression layer 112a between the soft magnetic layers 111a and 111b, which suppresses the generation of closure domains in the soft magnetic layers 111a and 111b. Further, the sensing circuit 12 includes a magnetic domain suppression layer 112b between the soft magnetic layers 111c and 111d that suppresses the generation of closure domains in the soft magnetic layers 111c and 111d. The sensing circuit 12 also includes a conductor layer 113 between the soft magnetic layer 111b and the soft magnetic layer 111c to reduce the resistance (here, electrical resistance) of the sensing circuit 12. FIG. The soft magnetic layers 111a, 111b, 111c, and 111d are referred to as soft magnetic layers 111 when they are not distinguished from each other. When the magnetic domain suppression layers 112a and 112b are not distinguished from each other, they are referred to as a magnetic domain suppression layer 112. FIG.

The substrate 11 is a substrate made of a non-magnetic material, for example, an electrically insulating oxide substrate such as glass or sapphire, a semiconductor substrate such as silicon, or a metal such as aluminum, stainless steel, or nickel-phosphorus-plated metal. substrates and the like. If the substrate 11 is a semiconductor substrate such as silicon, or a metal substrate such as aluminum, stainless steel, nickel-phosphorus-plated metal, etc., and has high conductivity, the side on which the sensing circuit 12 is provided may be used. An insulator layer for electrically insulating the substrate 11 and the sensing circuit 12 may be provided on the surface of the substrate 11 . Examples of insulators forming such insulator layers include oxides such as SiO ₂ , Al ₂ O ₃ and TiO ₂ and nitrides such as Si ₃ N ₄ and AlN. Here, it is assumed that the substrate 11 is made of glass. The thickness of such substrate 11 is, for example, 0.3 mm to 2 mm. Note that the thickness of the substrate 11 may have another value.

The soft magnetic layer 111 is composed of an amorphous alloy soft magnetic material exhibiting a magneto-impedance effect. As the soft magnetic material forming the soft magnetic layer 111, it is preferable to use an amorphous alloy in which refractory metals such as Nb, Ta, and W are added to an alloy containing Co as a main component. Such Co-based alloys include CoNbZr, CoFeTa, CoWZr, CoFeCrMnSiB, and the like. The thickness of the soft magnetic layer 111 is, for example, 100 nm to 1 μm.
Here, the soft magnetic material is a material with a so-called small coercive force, which is easily magnetized by an external magnetic field, but quickly returns to a state of no magnetization or low magnetization when the external magnetic field is removed.
Further, in this specification, an amorphous alloy and an amorphous metal refer to those having a structure that does not have a regular arrangement of atoms like a crystal and formed by a sputtering method or the like.

The domain suppression layer 112 suppresses the occurrence of closure domains in the soft magnetic layers 111 above and below the domain suppression layer 112 .
In general, the soft magnetic layer 111 tends to form a plurality of magnetic domains having different magnetization directions. In this case, a closure magnetic domain having an annular magnetization direction is formed. When the external magnetic field increases, the domain wall moves, the area of the magnetic domain whose magnetization direction is the same as the external magnetic field direction increases, and the area of the magnetic domain whose magnetization direction is opposite to the external magnetic field direction decreases. Then, when the external magnetic field is further increased, magnetization rotation occurs so that the magnetization direction is the same as that of the external magnetic field in the magnetic domain whose magnetization direction is different from that of the external magnetic field. Finally, the domain walls existing between adjacent magnetic domains disappear and become one magnetic domain (single magnetic domain). In other words, when the closure domain is formed, the Barkhausen effect occurs in which the domain walls forming the closure domain move discontinuously in a stepwise manner as the external magnetic field changes. This discontinuous movement of the domain wall causes noise in the magnetic sensor 10 and may cause a decrease in S/N in the output obtained from the magnetic sensor 10 . The magnetic domain suppression layer 112 suppresses the formation of a plurality of small magnetic domains in the soft magnetic layers 111 provided above and below the magnetic domain suppression layer 112 . This suppresses the formation of closure domains and suppresses the generation of noise due to the discontinuous movement of domain walls. Note that the magnetic domain suppressing layer 112 only needs to have the effect of reducing the number of magnetic domains formed, that is, increasing the size of the magnetic domains, compared to the case where the magnetic domain suppressing layer 112 is not included.

Examples of such magnetic domain suppression layers 112 include non-magnetic materials such as Ru and SiO ₂ and non-magnetic amorphous metals such as CrTi, AlTi, CrB, CrTa and CoW. The thickness of such a magnetic domain suppression layer 112 is, for example, 10 nm to 100 nm.

Conductive layer 113 reduces the resistance of sensitive circuit 12 . That is, the conductor layer 113 has a higher conductivity than the soft magnetic layer 111, and reduces the resistance of the sensing circuit 12 compared to the case where the conductor layer 113 is not included. A magnetic field is detected by a change in impedance (hereinafter referred to as impedance Z) (denoted as ΔZ) when alternating current is passed between the two terminals 13a and 13b of the sensing circuit 12. FIG. At this time, the higher the frequency of the alternating current, the greater the rate of change ΔZ/ΔH (impedance change rate ΔZ/ΔH hereinafter) of the impedance Z with respect to the change in the external magnetic field (here, expressed as ΔH). However, if the frequency of the alternating current is increased without the conductor layer 113, the impedance change rate ΔZ/ΔH will be reduced due to the stray capacitance. Therefore, the conductor layer 113 is provided to reduce the resistance of the sensing circuit 12 .

As such a conductor layer 113, a highly conductive metal or alloy is preferably used, and a highly conductive and non-magnetic metal or alloy is more preferably used. Such a conductor layer 113 may be made of metal such as Ag, Al, and Cu. The thickness of the conductor layer 113 is, for example, 10 nm to 1 μm. The conductive layer 113 may reduce the resistance of the sensing circuit 12 compared to the case where the conductive layer 113 is not included.

The upper and lower soft magnetic layers 111 sandwiching the magnetic domain suppression layer 112 and the upper and lower soft magnetic layers 111 sandwiching the conductor layer 113 are antiferromagnetically coupled (AFC) to each other. Antiferromagnetic coupling between the upper and lower soft magnetic layers 111 suppresses the demagnetizing field and improves the sensitivity of the magnetic sensor 10 .

(Operation of magnetic sensor 10)
Next, the operation of the magnetic sensor 10 will be explained.
FIG. 4 is a diagram for explaining the relationship between the magnetic field H applied in the longitudinal direction of the sensing portion 121 of the magnetic sensor 10 and the impedance Z of the magnetic sensor 10. As shown in FIG. In FIG. 4, the horizontal axis is the magnetic field H, and the vertical axis is the impedance Z. In FIG. The impedance Z is measured by passing an alternating current between the terminals 13b and 13c of the sensing circuit 12 shown in FIG. 3(a). Therefore, although the impedance Z is the impedance of the sensing circuit 12 , it is written as the impedance Z of the magnetic sensor 10 .

As shown in FIG. 4, the impedance Z of the magnetic sensor 10 increases as the magnetic field H applied in the longitudinal direction of the sensing portion 121 increases. Then, the impedance Z of the magnetic sensor 10 becomes smaller when the applied magnetic field H becomes larger than the anisotropic magnetic field Hk. In a range smaller than the anisotropic magnetic field Hk of the sensing part 121, if a portion where the change amount ΔZ of the impedance Z is steep with respect to the change amount ΔH of the magnetic field H (ΔZ/ΔH is large), a weak change in the magnetic field H can be obtained. can be taken out as the change amount ΔZ of the impedance Z. In FIG. 4, the center of the magnetic field H where ΔZ/ΔH is large is shown as the magnetic field Hb. That is, the amount of change (ΔH) in the magnetic field H in the vicinity of the magnetic field Hb (the range indicated by the arrow in FIG. 4) can be measured with high accuracy. Here, the magneto-impedance effect is greater at a portion where the variation ΔZ of the impedance Z is the steepest (ΔZ/ΔH is the largest), making it easier to measure the magnetic field or the change in the magnetic field. In other words, the steeper the change in impedance Z with respect to the magnetic field H, the higher the sensitivity. The magnetic field Hb is sometimes called the bias magnetic field. The magnetic field Hb is hereinafter referred to as a bias magnetic field Hb. It should be noted that the higher the frequency of the alternating current flowing through the sensing circuit 12, the higher the sensitivity.

(Manufacturing method of magnetic sensor 10)
The magnetic sensor 10 is manufactured as follows.
First, a photoresist pattern is formed on the substrate 11 by a known photolithographic technique to cover the area of the sensing circuit 12 excluding the planar shape thereof. Next, the soft magnetic layer 111a, the magnetic domain suppressing layer 112a, the soft magnetic layer 111b, the conductor layer 113, the soft magnetic layer 111c, the magnetic domain suppressing layer 112b, and the soft magnetic layer 111d are sequentially formed on the substrate 11, for example, by sputtering. Deposited according to the method. Then, the soft magnetic layer 111a, the magnetic domain suppression layer 112a, the soft magnetic layer 111b, the conductor layer 113, the soft magnetic layer 111c, the magnetic domain suppression layer 112b, and the soft magnetic layer 111d deposited on the photoresist are removed by photolithography. Remove with resist. Then, on the substrate 11, a soft magnetic layer 111a, a magnetic domain suppression layer 112a, a soft magnetic layer 111b, a conductor layer 113, a soft magnetic layer 111c, and a magnetic domain suppression layer 112b, which are processed into the planar shape of the sensing circuit 12, are formed. , and the soft magnetic layer 111d. That is, the magnetic sensor 10 is formed.

As described above, the soft magnetic layer 111 is imparted with uniaxial magnetic anisotropy in a direction crossing the longitudinal direction, for example, in the lateral direction (the y direction in FIG. 3A). The uniaxial magnetic anisotropy is obtained by subjecting the sensing circuit 12 formed on the substrate 11 to heat treatment at 400° C. in a rotating magnetic field of 3 kG (0.3 T) (heat treatment in a rotating magnetic field), followed by 3 kG (0.3 T). 3 T) in a static magnetic field at 400° C. (heat treatment in a static magnetic field). Uniaxial magnetic anisotropy may be imparted by magnetron sputtering during deposition of the soft magnetic layer 111 constituting the sensing circuit 12 instead of the heat treatment in the rotating magnetic field and the heat treatment in the static magnetic field. That is, the magnetic field formed by the magnet used in the magnetron sputtering method imparts uniaxial magnetic anisotropy to the soft magnetic layer 111 at the same time as the soft magnetic layer 111 is deposited.

In the manufacturing method described above, the connection portion 122 in the sensing circuit 12 is formed simultaneously with the sensing portion 121 . The pattern of the photoresist may be formed by excluding the plane shape of the sensing circuit 12 and the plane shape of the sensing circuit 12 and the terminal section 13 . In this case, the terminal portion 13 is formed simultaneously with the sensing portion 121 and the connecting portion 122 . Also, the connecting portion 122 and the terminal portion 13 may be made of conductive metal such as Al, Cu, Ag, and Au. Also, a conductive metal such as Al, Cu, Ag, or Au may be layered on the connection portion 122 and the terminal portion 13 formed at the same time as the sensing portion 121 .

Although the sensing circuit 12 includes the magnetic domain suppressing layer 112 and the conductor layer 113, either one or both of the magnetic domain suppressing layer 112 and the conductor layer 113 may be omitted.

(Magnetic sensor device 1 to which the first embodiment is applied)
Next, the magnetic sensor device 1 to which the first embodiment is applied will be described.
As described above, if the area of the current loop α formed by the wiring near the magnetic sensor 10 is reduced, the inductance is reduced and the sensitivity is improved. Therefore, in the magnetic sensor 10 included in the magnetic sensor device 1 to which the first embodiment is applied, the terminal portion 13c is provided, and the terminal portion 13a and the terminal portion 13c are connected by the turn-back wiring 14. I have to.

FIG. 5 is a diagram for stereoscopically explaining the magnetic sensor 10. As shown in FIG. 5(a) is a perspective view, and FIG. 5(b) is a side view of the magnetic sensor 10 of FIG. 5(a) viewed from the x-direction side. In FIG. 5(a), the x-direction, y-direction, and z-direction are set as in FIGS. 3(a) and 3(b). In the side view of FIG. 5B, the right direction of the paper is the y direction, and the upper direction of the paper is the z direction.

As shown in FIGS. 5(a) and 5(b), the magnetic sensor 10 is provided so that the turn-back wiring 14 connecting the terminal portions 13a and 13c is routed to the back side of the substrate 11. . Note that the folded wiring 14 routed to the back side of the substrate 11 is indicated by a broken line. The terminal portions 13b and 13c are connected to the connection terminals 20 and 30 for the AC current generating portion 200 and the detecting portion 300, respectively. The terminal portions 13b and 13c are arranged adjacent to each other. The folded wiring 14 is routed along the back surface of the substrate 11 from the end portion of the substrate 11, but the folded wiring 14 is drawn to the back surface side so that the length of the folded wiring 14 is shortened. A cut may be made in the substrate 11 at the portion to be turned. Alternatively, a through hole may be provided in the substrate 11 and the turn-back wiring 14 may be routed to the rear surface side.

6A to 6D are diagrams showing variations of the magnetic sensor 10. FIG. 6A shows the magnetic sensor 10 shown in FIGS. 3 and 5. FIG. In order to distinguish the variations of the magnetic sensors, the magnetic sensors 10 in FIGS. 6A to 6D are denoted as magnetic sensors 10a, 10b, 10c, and 10d, and folded wirings 14a, 14b, 14c, and 14d. When the magnetic sensors 10a, 10b, 10c, and 10d are not distinguished from each other, they are referred to as the magnetic sensor 10, and when the return wirings 14a, 14b, 14c, and 14d are not distinguished from each other, they are referred to as a return wiring 14. A folded wiring 14 hidden behind the back surface of the substrate 11 is indicated by a dashed line. On the back surface side of the substrate 11 , the folded wiring 14 is provided along the back surface of the substrate 11 . The sensing circuit 12 is the same in the magnetic sensors 10a, 10b, 10c and 10d.

In the magnetic sensor 10a shown in FIG. 6(a), the folded wiring 14a is linearly provided at the end of the sensing circuit 12 in the x direction from the terminal portion 13a to the terminal portion 13b, and is connected to the terminal portion 13c. ing. This magnetic sensor 10a is sometimes called an "end". In addition, the turn-back wiring 14a may be provided so as to partially overlap the sensing circuit 12 in plan view. Note that the term “planar view” refers to the case where the magnetic sensor 10 is viewed from the z direction through the substrate 11 .

In the magnetic sensor 10b shown in FIG. 6B, the folded wiring 14b is provided so as to cross the central portion of the sensing circuit 12 in the x direction in plan view. This magnetic sensor 10b is sometimes called "central".

In a magnetic sensor 10c shown in FIG. 6(c), a folded wiring 14c is provided so as to traverse the sensing circuit 12 in an M shape in plan view. This magnetic sensor 10c is sometimes called "M-shaped".

In the magnetic sensor 10d shown in FIG. 6D, the folded wiring 14d is provided so as to overlap the sensing portion 121 and the connection portion 122 of the sensing circuit 12 in plan view. That is, the turn-back wiring 14d has the same shape as the sensing circuit 12. FIG. This magnetic sensor 10d may be called "identical".
The direction of the high-frequency current flowing through the turn-back wiring 14d is opposite to the direction of the high-frequency current flowing through the sensing circuit 12, so that the magnetic fields generated by the currents cancel each other out. The sensing circuit 12 has a zigzag structure (meandering structure), and magnetic fields cancel each other out between adjacent sensing portions 121 . However, when the magnetic sensor 10 has an odd number of sensing portions 121, the magnetic fields are not canceled between adjacent sensing portions 121. FIG. Also, the magnetic field generated from the connecting portion 122 is not canceled. Therefore, by providing the folded wiring 14d over the sensing circuit 12, the magnetic field generated by the high-frequency current can be easily canceled. Therefore, the S/N of the signal detected by the detector 300 is improved.

7A to 7C are diagrams showing other variations of the magnetic sensor 10. FIG. 7A to 7C, the magnetic sensors 10e, 10f and 10g are indicated, and the turn-back wirings 14e, 14f and 14g are indicated. When the magnetic sensors 10e, 10f, and 10g are not distinguished from each other, they are referred to as the magnetic sensor 10, and when the return wirings 14e, 14f, and 14g are not distinguished from each other, they are referred to as a return wiring 14. A folded wiring 14 hidden behind the back surface of the substrate 11 is indicated by a dashed line. In addition, on the back surface side of the substrate 11 , the folded wiring 14 is provided along the back surface of the substrate 11 .

In the magnetic sensor 10e shown in FIG. 7(a), the sensing circuit 12 includes five (odd number) sensing portions 121, and the terminal portion 13a is provided on the y direction side of the -x direction side (upper left corner side of the paper surface). The terminal portion 13b is provided on the -y direction side (lower right corner side of the paper surface) of the x direction side. The terminal portion 13c is provided adjacent to the terminal portion 13b in the -y direction. That is, the terminal portion 13a and the terminal portion 13c are provided at diagonal positions facing each other on the magnetic sensor 10e. The turn-back wiring 14e is provided so as to obliquely cross the sensing circuit 12 in plan view from the terminal portion 13a toward the terminal portion 13b, and is connected to the terminal portion 13c.

In the magnetic sensor 10f shown in FIG. 7B, terminal portions 13a and 13b are provided at the central portion of the sensing circuit 12 in the x direction. The terminal portion 13c is also provided adjacent to the terminal portion 13b in the -y direction at the center portion of the magnetic sensor 10f in the x direction. The turn-back wiring 14f is provided so as to cross the central portion of the sensing circuit 12 in the -y direction in plan view from the terminal portion 13a toward the terminal portion 13b side, and is connected to the terminal portion 13c.

In a magnetic sensor 10g shown in FIG. 7(c), the sensing circuit 12 includes one sensing portion 121 having a longitudinal direction in the x direction, a terminal portion 13a is provided at the end on the -x direction side, and a terminal portion 13b is provided at the end on the +x direction side. The terminal portion 13c is provided adjacent to the terminal portion 13b in the x direction. The folded wiring 14g is provided so as to overlap the sensing portion 121 in a plan view so as to extend from the terminal portion 13a toward the terminal portion 13b, and is connected to the terminal portion 13c.
The direction of the high-frequency current flowing through the sensing portion 121 of the sensing circuit 12 is opposite to the direction of the high-frequency current flowing through the turn-back wiring 14g, and the magnetic fields generated by the currents cancel each other. Therefore, the S/N of the signal detected by the detector 300 is improved.

6(a) to (d) and FIGS. 7(a) to (c), the terminal portion 13b and the terminal portion 13c are provided adjacent to each other. Therefore, the area of the current loop (current loop α2 shown in FIG. 1A) formed by the wiring connecting the magnetic sensor 10 (terminal portions 13b, 13c) and the connection terminals 20, 30 is reduced. Therefore, the sensitivity of the magnetic sensor 10 is improved.

FIG. 8 is a diagram for explaining the sensitivity of the magnetic sensor device. 8A shows the relationship between the area of the current loop and the sensitivity, and FIG. 8B shows the relationship between the distance between the magnetic sensor 10 and the wiring and the sensitivity. In FIG. 8(a), the horizontal axis is the current loop area (mm ² ), and the vertical axis is the sensitivity (%/Oe). In FIG. 8B, the horizontal axis is the distance (mm) between the magnetic sensor 10 and the wiring, and the vertical axis is the sensitivity (%/Oe). Note that the sensitivity (%/Oe) is the change rate of the frequency of the magnetic sensor 10 with respect to the unit signal magnetic field strength.

Here, the current loop is a combination of the current loops α and β in FIG. 1(a), and a combination of the current loops α′ and β in FIG. 1(b). . Then, in the same manner as the magnetic sensor 10b shown in FIG. 6B, the wiring (turned wiring 14b in the magnetic sensor 10b) and the magnetic sensor By changing the distance between 10 and substrate 11, the area of the current loop (corresponding to current loop α' in FIG. 1(b)) is changed. The distance "0.1 mm" between the magnetic sensor 10 and the wiring in FIG. 8(b) corresponds to the magnetic sensor 10b in FIG. 6(b). At this time, the area of the current loop of the magnetic sensor device 1 is 11 mm ² . The current loop area of 11 mm ² is broken down into the area of the current loop α formed by the wiring near the magnetic sensor 10b of 1 mm ² and the area of the current loop β formed by the wiring near the detection unit 300 of 10 mm ² . is. That is, in the magnetic sensor device 1, the area of the current loop α (see FIG. 1A) is smaller than the area of the current loop β.

As shown in FIGS. 8A and 8B, the sensitivity (%/Oe) decreases as the distance between the magnetic sensor and the wiring increases and the area of the current loop increases. As shown in FIG. 8(a), when the area of the current loop is 56.5 mm ² or less, the sensitivity is 41.4%/Oe or more. On the other hand, when the area of the current loop is 72.0 mm ² or more, the sensitivity becomes 35.2%/Oe or less. In other words, in order to improve the sensitivity, it is preferable that the area of the current loop is 50 mm ² or less. Further, as shown in FIG. 8B, when the distance between the magnetic sensor 10 and the wiring is 4.7 mm or less, the sensitivity is 41.4%/Oe or more. On the other hand, when the distance between the magnetic sensor 10 and the wiring is 6.2 mm or more, the sensitivity becomes 35.2%/Oe or less. In other words, in order to improve the sensitivity, it is preferable that the distance between the magnetic sensor 10 and the wiring is 5 mm or less.

FIG. 9 is a diagram showing the sensitivity of the magnetic sensor device in variations of the magnetic sensor 10. In FIG. FIG. 9(a) shows the sensitivity measured with two samples A1 and A2 having the same structure, and FIG. 9(b) shows the sensitivity measured with two samples B and C having different structures. In FIG. 9A, “300 mm ² ” means that the area of the current loop is 300 mm ² , and the area of the current loop is increased by increasing the distance between the magnetic sensor and the wiring as described in FIG. is the case. "End" is the magnetic sensor 10a of FIG. 10c, and when the folded wiring 14c is provided across the sensing circuit 12 in an M shape, the "center" is the magnetic sensor 10b shown in FIG. This is the case where it is provided so as to traverse the central portion. The vertical axis represents sensitivity, which is shown in relative values (arbitrary units).

The area of the current loop for each of magnetic sensor 10a ("end"), magnetic sensor 10c ("M"), and magnetic sensor 10b ("middle") is 11 mm ² . That is, the area of the current loop α formed by the wires near the magnetic sensor 10a (“end”), the magnetic sensor 10c (“M shape”), and the magnetic sensor 10b (“center”) is 1 mm ² each, and the area near the detection unit 300 is 1 mm 2 . The area of the current loop β formed by the wiring of is 10 mm ² . That is, the area of the current loop α formed by the wiring near the magnetic sensor 10 is smaller than the area of the current loop β formed by the wiring near the detection unit 300 . Even if the area of the current loop is 300 mm ² , the area of the current loop β formed by the wiring near the detection unit 300 is 10 mm ² . Therefore, when the area of the current loop is 300 mm ² , the area of the current loop formed by the wiring near the magnetic sensor (the current loop α′ formed by the wiring near the magnetic sensor 10′ in FIG. 1B) is It is larger than the area of the current loop β formed by adjacent wiring.

In FIG. 9B, “60 mm ² ” means that the area of the current loop is 60 mm ² , and as described in FIG. 8, the space between the magnetic sensor and the wiring is increased to increase the area of the current loop. is the case. "Central" means the magnetic sensor 10b of FIG. 6(b), and when the turn-back wiring 14b is provided across the center of the sensing circuit 12, "same" means the magnetic sensor 10d of FIG. 6(d). In this case, the folded wiring 14d is provided along the sensing portion 121 and the connecting portion 122 of the sensing circuit 12. FIG. The vertical axis represents sensitivity, which is shown in relative values (arbitrary units).

The area of the current loop for both the magnetic sensor 10b ("middle") and the magnetic sensor 10d ("identical") is 11 mm ² . That is, the area of the current loop α formed by the wires near the magnetic sensor 10b (“center”) and the magnetic sensor 10d (“same”) is 1 mm ² , and the area of the current loop β formed by the wiring near the detection unit 300 is 10 ^mm2 . That is, the area of the current loop α formed by the wiring near the magnetic sensor 10 is smaller than the area of the current loop β formed by the wiring near the detection unit 300 . Even when the area of the current loop is 60 mm ² , the area of the current loop β formed by the wiring near the detection unit 300 is 10 mm ² . Therefore, when the area of the current loop is 60 mm ² , the area of the current loop formed by the wiring near the magnetic sensor (the current loop α′ formed by the wiring near the magnetic sensor 10′ in FIG. 1B) is It is larger than the area of the current loop β formed by adjacent wiring.

As shown in FIG. 9(a), the sensitivity is improved over the 300 mm ² current loop at any of the "end", "M" and "center". Similarly, as shown in FIG. 9(b), the sensitivity is improved over the current loop of 60 mm ² for both "middle" and "same".
As described above, in the magnetic sensor device 1 to which the first embodiment is applied, the area of the current loop α formed by the wiring near the magnetic sensor 10 is less than the area of the current loop β formed by the wiring near the detection unit 300. Since it is made small, the sensitivity of the magnetic sensor device 1 is improved.

In addition, in the above description, the folded wiring 14 is provided so as to be turned on the back surface side of the substrate 11 , but it may be provided on the front surface side of the substrate 11 .
FIG. 10 is a diagram illustrating another magnetic sensor 10. FIG. 10(a) is a perspective view, and FIG. 10(b) is a side view of the magnetic sensor 10 of FIG. 10(a) viewed from the x direction. In FIG. 10(a), the x-direction, y-direction, and z-direction are set as in FIGS. 5(a) and 5(b). In the side view of FIG. 10(b), the right direction of the paper surface is the y direction, and the upper direction of the paper surface is the z direction.

As shown in FIGS. 10A and 10B, the magnetic sensor 10 is provided on the surface side of the substrate 11 with a turn-back wiring 14 that connects the terminal portions 13a and 13c. The turn-back wiring 14 is electrically insulated from the sensing circuit 12 by providing an electrically insulating insulating layer 115 in a portion overlapping the sensing circuit 12 . The turn-back wiring 14 is provided along the surface of the insulator layer 115 . In addition, the folded wiring 14 is provided so as to bypass the terminal portion 13b so as not to overlap the terminal portion 13b. Examples of insulators forming the insulator layer 115 include oxides such as SiO ₂ , Al ₂ O ₃ and TiO ₂ and nitrides such as Si ₃ N ₄ and AlN.

As shown in FIG. 10(b), when the turn-back wiring 14 is provided on the front surface side of the substrate 11, the current loop α1 in the magnetic sensor 10 (FIG. 1(a) )), the area of the current loop formed by the turn-back wiring 14 and the sensing circuit 12 can be reduced. As a result, the current loop α1 in the magnetic sensor 10 becomes smaller, the current loop α formed by the wiring near the magnetic sensor 10 becomes smaller, and the sensitivity of the magnetic sensor device 1 is further improved.

In the above description, the magnetic sensor 10 has the terminal portion 13 c on the surface of the substrate 11 . However, the terminal portion 13 c may be provided on the back surface of the substrate 11 . Also, the terminal portion 13c may be the end portion of the folded wiring 14 without providing the terminal portion 13c provided on the substrate 11 . The terminal portion 13 c here includes the end portion of the folded wiring 14 . That is, the terminal portion 13b and the terminal portion 13c (including the ends of the folded wiring 14) are provided adjacent to each other so that the current loop formed by the wiring connecting the magnetic sensor 10 and the connection terminals 20 and 30 is small. It is good if it is 3A, the distance D1 between the terminal portion 13b and the terminal portion 13c (including the end portion of the folded wiring 14) is equal to the distance between the terminal portion 13a and the terminal portion 13b. It should be shorter than D2.

[Second embodiment]
In the magnetic sensor device 1 to which the first embodiment is applied, the turn-back wiring 14 of the magnetic sensor 10 is provided on the back side or front side of the substrate 11 . In the magnetic sensor device to which the second embodiment is applied, the turn-back wiring 14 of the magnetic sensor 10 is provided on the substrate 11 . In the second embodiment, except for the magnetic sensor 10, other configurations are the same as those of the first embodiment. Therefore, the magnetic sensor 10, which is a different part, will be described, and the other configurations will be described. omitted. Therefore, the magnetic sensor device to which the second embodiment is applied is referred to as a magnetic sensor device 1. FIG. As in the magnetic sensor 10, configurations having the same functions are given the same reference numerals as in the magnetic sensor 10 of the first embodiment.

FIG. 11 is a diagram for explaining the magnetic sensor 10 included in the magnetic sensor device 1 to which the second embodiment is applied. 11(a) is a perspective view, and FIG. 11(b) is a side view of the magnetic sensor 10 of FIG. 11(a) viewed from the x direction. In FIG. 11(a), the x-direction, y-direction, and z-direction are set as in FIGS. 3(a) and 3(b). In the side view of FIG. 5B, the right direction of the paper is the y direction, and the upper direction of the paper is the z direction.

In the magnetic sensor 10 , the folded wiring 14 is provided on the substrate 11 on the x-direction side of the sensing circuit 12 .

FIGS. 12A to 12C are diagrams showing variations of the magnetic sensor 10 included in the magnetic sensor device 1 to which the second embodiment is applied. 12(a) to 12(c) are denoted by magnetic sensors 10h, 10i and 10j, and are denoted by return wirings 14h, 14i and 14j in order to distinguish the magnetic sensors of the variations. When the magnetic sensors 10h, 10i, and 10j are not distinguished from each other, they are referred to as the magnetic sensor 10, and when the return wirings 14h, 14i, and 14j are not distinguished from each other, they are referred to as a return wiring 14. FIG.

In a magnetic sensor 10h shown in FIG. 12(a), a turn-back wiring 14h is provided so as to be linearly turned back from the terminal portion 13a to the terminal portion 13b side along the side surface of the sensing circuit 12 in the x direction. It is connected.

In the magnetic sensor 10i shown in FIG. 12(b), the folded wiring 14i is provided along the sensing portion 121 and the connecting portion 122 of the sensing circuit 12 and connected to the terminal portion 13c.
In the magnetic sensor 10i, the direction of the high-frequency current flowing through the sensing circuit 12 is opposite to the direction of the high-frequency current flowing through the turn-back wiring 14i. Therefore, as described with reference to FIG. 6(d), the magnetic fields generated by the high frequency current cancel each other out. Therefore, the S/N of the signal detected by the detector 300 is improved.

In the magnetic sensor 10j shown in FIG. 12(c), the sensing circuit 12 is composed of one sensing portion 121 having its longitudinal direction in the x direction. The return wiring 14j is provided so as to be folded back from the terminal portion 13a toward the terminal portion 13b along the sensing portion 121, and is connected to the terminal portion 13c. Since the sensing portion 121 of the sensing circuit 12 and the turn-back wiring 14j are arranged in parallel, the direction of the high-frequency current flowing through the sensing portion 121 of the sensing circuit 12 is opposite to the direction of the high-frequency current flowing through the turn-back wiring 14j. The magnetic fields produced by the current cancel each other out. Therefore, the S/N of the signal detected by the detector 300 is improved.

The magnetic sensor 10 of the variation shown in FIGS. 12(a) to 12(c) is provided with the terminal portion 13b and the terminal portion 13c adjacent to each other. Therefore, the area of the current loop (current loop α2 shown in FIG. 1A) formed by the wiring connecting the magnetic sensor 10 (terminal portions 13b, 13c) and the connection terminals 20, 30 is reduced. Therefore, the sensitivity of the magnetic sensor device 1 is improved.

In the above description, the magnetic sensor 10 has the terminal portion 13 c on the surface of the substrate 11 . However, the terminal portion 13 c may be the end portion of the folded wiring 14 without providing the terminal portion 13 c provided on the substrate 11 . The terminal portion 13 c here includes the end portion of the folded wiring 14 . That is, the terminal portion 13b and the terminal portion 13c (including the ends of the folded wiring 14) are provided adjacent to each other so that the current loop formed by the wiring connecting the magnetic sensor 10 and the connection terminals 20 and 30 is small. It is good if it is

[Third Embodiment]
In the magnetic sensor device 1 to which the first embodiment and the second embodiment are applied, the return wiring 14 is provided in the magnetic sensor 10, and the wiring connecting the magnetic sensor 10 and the connection terminals 20 and 30 is formed. The area of the current loop (current loop α2 shown in FIG. 1(a)) is reduced. In the third embodiment, instead of the turn-back wiring 14, the sensing circuit 12 is turned back. In the third embodiment, except for the magnetic sensor 10, other configurations are the same as those in the first and second embodiments, so the magnetic sensor 10, which is a different part, will be described. , the description of other configurations is omitted. Therefore, the magnetic sensor device to which the third embodiment is applied is referred to as a magnetic sensor device 1. FIG. In addition, like the magnetic sensor 10, configurations having the same functions are given the same reference numerals as those of the magnetic sensors 10 of the first embodiment and the second embodiment.

FIG. 13 is a diagram showing variations of the magnetic sensor 10 to which the third embodiment is applied. The magnetic sensor 10 shown in FIG. 13 is referred to as a magnetic sensor 10k in order to distinguish it from the magnetic sensors 10 described above.

The magnetic sensor 10k shown in FIG. 13 comprises sensing circuits 12a, 12b. A sensing circuit 12a is provided outside, and a sensing circuit 12b is provided inside. A terminal portion 13a is provided at the y-direction end of the sensing circuit 12a, and a terminal portion 13b is provided at the −y-direction end of the sensing circuit 12a. A terminal portion 13a of the sensing circuit 12a is connected to the sensing circuit 12b. A terminal portion 13c is provided at the end of the sensing circuit 12b on the -y direction side. Terminal portion 13b and terminal portion 13c are provided adjacent to each other. That is, the sensing circuit 12b is provided instead of the turn-back wiring 14 in the first and second embodiments. Sensing circuit 12b is another example of another sensing circuit and folded member. If the sensing circuit 12a and the sensing circuit 12b are provided continuously, it is not necessary to provide the terminal portion 13a.
In the magnetic sensor 10k, the direction of the high frequency current flowing through the sensing circuit 12a is opposite to the direction of the high frequency current flowing through the sensing circuit 12b. Therefore, as described with reference to FIG. 6(d), the magnetic fields generated by the high frequency current cancel each other out. Therefore, the S/N of the signal detected by the detector 300 is improved.

In the magnetic sensor 10 of the variation shown in FIG. 13, the terminal portion 13b and the terminal portion 13c are provided adjacent to each other. Therefore, the area of the current loop (current loop α2 shown in FIG. 1A) formed by the wiring connecting the magnetic sensor 10 (terminal portions 13b, 13c) and the connection terminals 20, 30 is reduced. Therefore, the sensitivity of the magnetic sensor device 1 is improved.

[Fourth Embodiment]
The magnetic sensor 10 included in the magnetic sensor device 1 to which the first, second, and third embodiments are applied has one sensing circuit 12 . On the other hand, the magnetic sensor 40 provided in the magnetic sensor device 2 to which the fourth embodiment is applied has two superimposed sensing circuits 12A and 12B.

FIG. 14 is a diagram illustrating a magnetic sensor device 2 to which the fourth embodiment is applied.
A magnetic sensor device 2 to which the third embodiment is applied includes a magnetic sensor 40 , an alternating current generator 200 and a detector 300 . The magnetic sensor 40 includes sensing circuits 12A and 12B including a sensing portion 121 (see FIG. 15 described later) whose impedance changes with changes in the magnetic field based on the magneto-impedance effect. The sensitive circuits 12A, 12B are superimposed. The magnetic sensor 40 is connected to the alternating current generator 200 and the detector 300 via connection terminals 20 and 30 . The alternating current generator 200, the detector 300, and the connection terminals 20 and 30 are the same as in the first embodiment. The sensing circuit 12A is an example of a first sensing circuit, and the sensing circuit 12B is an example of a second sensing circuit.

The sensing circuit 12A is connected to the terminals 13aA and 13bA, and the sensing circuit 12B is connected to the terminals 13aB and 13bB. Terminal portion 13bA and terminal portion 13bB are connected by connecting wire 15 . The sensing circuit 12A and the sensing circuit 12B are connected in series. Terminal portion 13aA and connection terminal 20 are connected, and terminal portion 13aB and connection terminal 30 are connected. In the magnetic sensor 40, a current flows from the terminal portion 13aA to the terminal portion 13aB via the sensing circuit 12A, the connection line 15, and the sensing circuit 12B. Since the sensing circuit 12A and the sensing circuit 12B are connected in series, the directions of the currents flowing in the sensing circuit 12A and the sensing circuit 12B are opposite to each other.

As in the first embodiment, FIG. 14 shows a current loop α formed between the magnetic sensor 40 and the connection terminals 20 and 30, and a current loop α formed between the connection terminals 20 and 30 and the detection unit 300. and the current loop β that is applied. The current loop α formed between the magnetic sensor 40 and the connection terminals 20 and 30 is the current loop α formed by the wiring near the magnetic sensor 40, and is formed between the connection terminals 20 and 30 and the detection unit 300. is the current loop β formed by wiring in the vicinity of the detection unit 300 . As in the first embodiment, the current loop α formed by the wiring near the magnetic sensor 40 consists of a current loop α1 in the magnetic sensor 40 and a current loop α2 between the magnetic sensor 40 and the connection terminals 20 and 30. It consists of

As shown in FIG. 14, the distance between the centers of the terminal portions 13aA and 13aB is greater than the distance between the centers of the terminal portions 13aA and 13bA and the distance between the centers of the terminal portions 13aA and 13bB. short. Therefore, the area of the current loop α2 is smaller than that of the current loop α'2 in the magnetic sensor device 1' to which the first embodiment is not applied (see FIG. 1(b)).

A current loop α1 in the magnetic sensor 40 is a current loop between the sensing circuit 12A and the sensing circuit 12B which are arranged in an overlapping manner. On the other hand, the current loop α'1 of the magnetic sensor 10' in the magnetic sensor device 1' is a current loop in one sensing circuit 12. FIG. The area of the current loop α1 and the area of the current loop α'1 are smaller than the area of the current loop α'2, and the difference is also small.

Therefore, the area of the current loop α formed by the wiring near the magnetic sensor 40 in the magnetic sensor device 2 is the magnetic sensor device 1 to which the first embodiment, the second embodiment, and the third embodiment are applied. is smaller than the current loop β formed by wiring in the vicinity of the detection unit 300. Therefore, the sensitivity of the magnetic sensor device 2 is improved.

FIG. 15 is a plan view illustrating an example of the sensing circuits 12A and 12B. In FIG. 15, the horizontal direction of the paper is the x direction, the upward direction of the paper is the y direction, and the surface direction of the paper is the z direction. The sensing circuit 12A and the sensing circuit 12B have the same planar shape. Therefore, the sensing circuits 12A and 12B are hereinafter referred to as sensing circuits 12A/12B. The same is true for others.

Here, it is assumed that the sensing circuit 12A is provided on the substrate 11A and the sensing circuit 12B is provided on the substrate 11B. The substrates 11A/11B are similar to the substrate 11 described in the first embodiment. The substrates 11A/11B have, for example, a rectangular planar shape. The planar shape of the substrates 11A/11B is several millimeters square to several tens of millimeters square. For example, the length in the x direction is 3 mm to 20 mm, and the length in the y direction is 3 mm to 20 mm. Note that the size of the planar shape of the substrates 11A/11B may be other values. The substrate 11A is an example of a first substrate, and the substrate 11B is an example of a second substrate.

The sensing circuits 12A/12B include a plurality of sensing portions 121 arranged in parallel, and a connection portion 122 connecting the sensing portions 121 in series in a meandering structure. Terminals 13aA/13aB are provided at one end of sensing circuits 12A/12B, and terminals 13bA/13bB are provided at the other end of sensing circuits 12A/12B. The sensing portion 121 and the connection portion 122 are the same as the sensing circuit 12 of the magnetic sensor 10 described in the first embodiment. The terminal portions 13aA/13aB and the terminal portions 13bA/13bB are the same as the terminal portions 13a and 13b of the magnetic sensor 10 described in the first embodiment. Note that the magnetic sensor 40 does not have the terminal portion 13c provided in the magnetic sensor 10 described in the first embodiment (see FIG. 3A).

The cross-sectional structure of the sensing circuits 12A/12B is the same as that of the sensing circuit 12 of the magnetic sensor 10 described in the first embodiment (see FIG. 3(b)).

FIG. 16 is a diagram illustrating the configuration of the magnetic sensor 40. As shown in FIG. FIG. 16(a) is a perspective view of the magnetic sensor 40, and FIG. 16(b) is a diagram for explaining currents and magnetic fields in the two sensing circuits 12A and 12B. The x, y and z directions in FIGS. 16(a) and 16(b) correspond to those in FIG.

The magnetic sensor 40 is configured by stacking a sensing circuit 12A and a sensing circuit 12B. That is, the sensing circuit 12A and the sensing circuit 12B have the same planar shape. , the connection portion 122 and the terminal portions 13aB and 13bB are arranged to overlap each other. Terminal portion 13bA and terminal portion 13bB are connected by connecting wire 15 . The terminal portion 13aA is connected to the connection terminal 20, and the terminal portion 13aB is connected to the connection terminal 30 (see FIG. 14(a)).

The connection line 15 is made of a conductor. Such conductors include Al, Cu, Au, Ag, and alloys thereof. That is, the sensing circuit 12A and the sensing circuit 12B are electrically connected to each other via the terminal portion 13bA and the terminal portion 13bB.

The distance between the centers of the terminal portions 13aA and 13aB is shorter than the distance between the centers of the terminal portions 13aA and 13bA and the distance between the centers of the terminal portions 13aA and 13bB. Therefore, as shown in FIG. 14(a), the current loop α2 between the magnetic sensor 40 and the connection terminals 20 and 30 is the same as that between the magnetic sensor 10' and the connection terminals 20 and 30 shown in FIG. 1(b). becomes smaller than the current loop α'2 between

The area of the current loop α1 in the magnetic sensor 40 is the area between the sensing circuit 12A and the sensing circuit 12B facing each other.

Therefore, the area of the current loop α(α1+α2) created by the wiring near the magnetic sensor 40 provided in the magnetic sensor device 2 shown in FIG. It is smaller than the area of the current loop α'(α'1+α'2). As a result, the magnetic sensor device 2 has a smaller inductance due to the current loop than the magnetic sensor device 1'.

A high-frequency current flows between the terminal portion 13aA and the terminal portion 13aB. Since it is a high-frequency current, the direction of the current flowing between the terminal portion 13aA on the side of the sensing circuit 12A and the terminal portion 13aB on the side of the sensing circuit 12B alternates. In FIG. 16A, the outline arrow I indicates the direction of the current when the current flows from the terminal portion 13aA to the terminal portion 13aB. Since the sensing circuit 12A and the sensing circuit 12B are connected in series, the current flowing through the sensing circuit 12A and the current flowing through the sensing circuit 12B are the same in magnitude and flow in opposite directions.

In FIG. 16(b), in the magnetic sensor 40, the sensing circuit 12A and the sensing circuit 12B arranged in an overlapping manner are shown in parallel with being shifted in the xy plane. FIG. 16(b) shows the case where the current I flows from the terminal portion 13aA to the terminal portion 13aB. In FIG. 16(b), the directions in which the current I flows are indicated by white arrows.

As shown in FIG. 16(b), the sensing circuit 12A and the sensing circuit 12B, which are superimposed, have the same magnitude of the current I and the opposite directions of flow. Therefore, the magnitude of the magnetic field HI generated around the current path of the sensing circuit _12A and the magnitude of the magnetic field _HI generated surrounding the current path of the sensing circuit 12B are equal and opposite in direction. That is, the magnetic field generated by the sensing circuit 12A cancels out the magnetic field generated by the sensing circuit 12B. As a result, the magnetic field generated in the magnetic sensor 40 by the high-frequency current flowing through the sensing circuit 12A and the sensing circuit 12B is greater than that of the magnetic sensor 10' having only the sensing circuit 12A or the sensing circuit 12B (see FIG. 1(b)). become weak. Therefore, the noise that affects the high-frequency current due to the generation of the magnetic field is reduced. This improves the sensitivity-to-noise ratio (S/N ratio) of the magnetic sensor 40 . In FIG. 16(b), the magnetic field generated by the current _I is denoted as the magnetic field HI and indicated by an arc-shaped arrow.

FIG. 17 is a diagram for explaining how the two sensing circuits 12A and 12B in the magnetic sensor 40 are stacked. FIG. 17(a) is an arrangement in which two sensing circuits 12A and 12B are opposed inside, FIG. 17(b) is an arrangement in which two sensing circuits 12A and 12B are opposed outside, and FIG. ) is an arrangement in which two sensing circuits 12A and 12B are stacked, and FIG. 17(d) is an arrangement in which two sensing circuits 12A and 12B are provided on the front and back sides of one substrate 11C. The sensing circuits 12A and 12B shown in FIGS. 17(a) to 17(c) are sectional views taken along line XVII--XVII in FIG.

In the magnetic sensor 40 shown in FIG. 17A, the sensing circuit 12A provided on the substrate 11A and the sensing circuit 12B provided on the substrate 11B face each other inside. As shown, the sensing circuit 12B on the substrate 11B side is arranged in the -z direction. In this case, an insulator layer may be provided between the sensing circuits 12A and 12B for electrical isolation.

In the magnetic sensor 40 shown in FIG. 17(b), the sensing circuit 12A provided on the substrate 11A and the sensing circuit 12B provided on the substrate 11B face each other on the outside. , the sensing circuit 12A on the substrate 11A side is arranged in the -z direction.

In the magnetic sensor 40 shown in FIG. 17(c), a sensing circuit 12A provided on a substrate 11A and a sensing circuit 12B provided on a substrate 11B are stacked in the +z direction.

A magnetic sensor 40 shown in FIG. 17D has a sensing circuit 12A on the front side of a substrate 11C and a sensing circuit 12B on the back side of the substrate 11C.

The two sensing circuits 12 (the sensing circuits 12A and 12B) in the magnetic sensor 40 may be superimposed in any one of FIGS. 17(a) to 17(d). In the magnetic sensor 40 shown in FIGS. 17A to 17D, the sensing portions 121 and the connecting portions 122 of the sensing circuits 12A and 12B face each other. Moreover, the terminal portions 13aA and 13aB and the terminal portions 13bA and 13bB face each other.

FIG. 18 is a diagram for explaining sensitivity in the magnetic sensor device 2 using the magnetic sensor 40 in which two sensing circuits 12 are stacked. 18(a) shows the relationship between the area of the current loop and the sensitivity, and FIG. 18(b) shows the relationship between the distance between the two sensing circuits 12 and the sensitivity. In FIG. 18(a), the horizontal axis is the current loop area (mm ² ) and the vertical axis is the sensitivity (%/Oe). In FIG. 18(b), the horizontal axis is the interval (mm) between the two sensing circuits 12, and the vertical axis is the sensitivity (%/Oe). Note that the sensitivity (%/Oe) is the change rate of the frequency of the magnetic sensor 10 with respect to the unit signal magnetic field strength.

Here, the current loop is a combination of the current loop α and the current loop β in FIG. The area of the current loop is changed by changing the distance between the two sensing circuits 12 (the sensing circuits 12A and 12B). The interval "0.2 mm" between the sensing circuits 12 in FIG. 18(b) corresponds to the case where the sensing circuits 12A and 12B shown in FIG. 17(a) are arranged so as to face each other inside. The corresponding current loop area of the magnetic sensor device 2 is 12 mm ² . The current loop area of 12 mm ² is broken down into the area of the current loop α formed by the wiring near the magnetic sensor 10b, which is 2 mm ² , and the area of the current loop β, formed by the wiring near the detection unit 300, which is 10 mm ² . is.

As shown in FIGS. 18(a) and 18(b), the sensitivity (%/Oe) decreases as the distance between the two sensing circuits 12 increases and the area of the current loop increases. As shown in FIG. 18(a), when the area of the current loop is 41.0 mm ² or less, the sensitivity is 61.5%/Oe or more. On the other hand, when the current loop area is 210.0 mm ² , the sensitivity drops to 46.4%/Oe. In other words, in order to improve the sensitivity, it is preferable that the area of the current loop is 50 mm ² or less. Further, as shown in FIG. 18(b), when the distance between the sensing circuits 12 is 3.1 mm or less, the sensitivity is 46.4%/Oe or more. On the other hand, when the spacing between the sensing circuits 12 is 20.0 mm, the sensitivity drops to 46.4%/Oe. That is, in order to improve the sensitivity, it is preferable that the interval between the sensing circuits 12 is 5 mm or less.

FIG. 19 shows another sensitivity of the magnetic sensor device 2 comprising a magnetic sensor 40 with two superimposed sensing circuits 12A, 12B. In FIG. 19, the case in which the magnetic sensor 40 is provided is described as "two layers". The area of the current loop in this case is 12 mm ² . The magnetic sensor 40 shows sensitivities measured with two samples A1 and A2 having the same structure. In FIG. 19, “300 mm ² ” shown for comparison means that the area of the current loop is 300 mm ² explained in FIG. This is the case where the area of the current loop is increased by increasing the current loop area. The vertical axis represents sensitivity, which is shown in relative values (arbitrary units).

The area of the current loop α formed by the wiring near the magnetic sensor 40 is 1 mm ² , and the area of the current loop β formed by the wiring near the detection unit 300 is 10 mm ² . That is, the area of the current loop α formed by the wiring near the magnetic sensor 40 is smaller than the area of the current loop β formed by the wiring near the detection unit 300 .
Then, as shown in FIG. 19, in the magnetic sensor 40 in which the two sensing circuits 12A and 12B are superimposed ("duplicated"), the sensitivity is improved as compared with the case where the current loop is 300 mm ² .

In the magnetic sensor 40 provided in the magnetic sensor device 2 to which the fourth embodiment is applied, the two sensing circuits 12A and 12B are superimposed so that the noise due to the magnetic field generated by the current (noise) N is suppressed, and the sensitivity-to-noise ratio (S/N ratio) is improved. Therefore, if the sensitivity-to-noise ratio (S/N ratio) is improved, the sensing circuit 12A and the sensing circuit 12B do not have to have the same planar shape. The current paths may overlap in plan view.

[Fifth embodiment]
A magnetic sensor 40 provided in the magnetic sensor device 2 to which the fourth embodiment is applied is configured by stacking two sensing circuits 12A and 12B. On the other hand, in the magnetic sensor 50 provided in the magnetic sensor device to which the fifth embodiment is applied, one sensing circuit 12 and the current circuit 16 with overlapping current paths are overlapped. . Other parts are the same as the magnetic sensor device 2 to which the fourth embodiment is applied. Here, description of other similar configurations is omitted, and the magnetic sensor 50 will be described. One sensing circuit 12 is the same as the sensing circuit 12A described in the fourth embodiment. Terminal portions 13aA and 13bA are denoted as terminal portions 13a and 13b.

FIG. 20 is a diagram illustrating the configuration of the magnetic sensor 50 in the magnetic sensor device to which the fifth embodiment is applied. 20(a) is a perspective view of the magnetic sensor 50, and FIG. 20(b) is a diagram for explaining the current and magnetic field in the sensing circuit 12 and the current circuit 16. FIG. The x direction, y direction and z direction in FIGS. 20(a) and 20(b) are the same as in FIGS. 16(a) and (b).

The magnetic sensor 50 is constructed by stacking the sensing circuit 12 and the current circuit 16 . The current path of the current circuit 16 overlaps the current path of the sensing circuit 12 . When viewed from above, the current circuit 16 has a current path overlaid on the sensing portion 121, the connection portion 122, and the terminal portions 13a and 13b of the sensing circuit 12. As shown in FIG. The current circuit 16 is provided with a terminal portion 16a at a portion facing the terminal portion 13a and a terminal portion 16b at a portion facing the terminal portion 13b. Terminal portion 13 b and terminal portion 16 b are connected by connecting wire 15 . The terminal portion 13a is connected to the connection terminal 20, and the terminal portion 16a is connected to the connection terminal 30 (see FIG. 1A). The distance between the centers of the terminal portions 13a and 16a is shorter than the distance between the centers of the terminal portions 13a and 13b and the distance between the centers of the terminal portions 13a and 16b. Therefore, similarly to the magnetic sensor device 1 shown in FIG. It is smaller than the current loop α'2 between the magnetic sensor 10' and the connection terminals 20 and 30 in the magnetic sensor device 1' shown in (b).

The area of the current loop (corresponding to the current loop α1 in FIG. 1(a)) in the magnetic sensor 50 is the area between the sensing circuit 12 and the current circuit 16 facing each other. Therefore, the area of the current loop (corresponding to the current loop α1 in FIG. 1A) in the magnetic sensor 50 is the area of the current loop α1 in the magnetic sensor 40 of the magnetic sensor device 2 to which the fourth embodiment is applied. difference is small.

Therefore, the area of the current loop (corresponding to the current loop α(α1+α2) in FIG. 1(a)) formed by the wiring near the magnetic sensor 50 is the current generated by the wiring near the magnetic sensor 10′ shown in FIG. 1(b). It is smaller than the area of the loop α'(α'1+α'2). This reduces the inductance in the magnetic sensor device to which the fifth embodiment is applied.

The current circuit 16 is made of a non-magnetic, low-permeability conductor. Such conductors include Al, Cu, Au, Ag, and alloys thereof.

A high-frequency current flows between the terminal portion 13a and the terminal portion 16a. Since it is a high-frequency current, the direction of the current flowing between the terminal portion 13a and the terminal portion 16a alternates. In FIG. 20( a ), the outline arrow I indicates the direction of the current when the current flows from the terminal portion 13 a of the sensing circuit 12 to the terminal portion 16 a of the current circuit 16 . Since the sensing circuit 12 and the current circuit 16 are connected in series, the current flowing through the sensing circuit 12 and the current flowing through the current circuit 16 have the same magnitude and flow in opposite directions.

In FIG. 20(b), in the magnetic sensor 50, the sensing circuit 12 and the current circuit 16 arranged in an overlapping manner are shown in parallel with being shifted in the xy plane. 20(b) shows the case where the current I flows from the terminal portion 13a to the terminal portion 16a of the current circuit 16. As shown in FIG. In FIG. 20(b), the directions in which the current I flows are indicated by white arrows.

As shown in FIG. 20(b), the sensing circuit 12 and the current circuit 16, which are superimposed, have the same magnitude of the current I and opposite directions. Therefore, the magnetic field HI generated around the current path of the sensing circuit 12 and the magnetic field _HI generated around the current path of the current circuit 16 are equal in _magnitude and opposite in direction. That is, the magnetic field generated by the sensing circuit 12 and the magnetic field generated by the current circuit 16 cancel each other out. As a result, the magnetic field generated in the magnetic sensor 50 by the high-frequency current flowing through the sensing circuit 12 and the current circuit 16 is weaker than in the case of the magnetic sensor 10' composed of the sensing circuit 12 (see FIG. 1(b)). . Therefore, the noise that affects the high-frequency current due to the generation of the magnetic field is reduced. This improves the sensitivity-to-noise ratio (S/N ratio) of the magnetic sensor 50 . In FIG. 20(b), the magnetic field generated by the current _I is expressed as a magnetic field HI and indicated by an arc-shaped arrow.

In the magnetic sensor 50, the sensing circuit 12 and the current circuit 16 may be overlapped in the same manner as in FIG. 17, the sensing circuit 12A is replaced with the sensing circuit 12, and the sensing circuit 12B is replaced with the current circuit 16. In FIG.

In the magnetic sensor 50 of the fifth embodiment, by overlapping the sensing circuit 12 and the current circuit 16, the noise (noise) N due to the magnetic field generated by the current is suppressed, and the sensitivity to noise ratio (S/N ratio) improves. If the sensitivity-to-noise ratio (S/N ratio) is improved, the current paths of the sensing circuit 12 and the current circuit 16 may not completely overlap when viewed from above, and the sensing circuit 12 and the current circuit 16 may have at least one current path. The current paths of the portions may overlap in plan view.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and combinations may be made as long as they do not violate the gist of the present invention.

1, 1', 2... Magnetic sensor devices 10, 10', 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10h, 10i, 10j, 10k, 40, 50... Magnetic sensors 11, 11A, 11B , 11C... substrate, 12, 12a, 12b, 12A, 12B... sensing circuit, 13, 13a, 13b, 13c, 13aA, 13bA, 13bB, 16a, 16b... terminal portion, 14, 14a, 14b, 14c, 14d, 14e , 14f, 14g, 14h, 14i, 14j... folding wiring, 15... connection wire, 16... current circuit, 20, 30... connection terminal, 111, 111a, 111b, 111c, 111d... soft magnetic layer, 112, 112a, 112b... Magnetic domain suppression layer 113... Conductor layer 115... Insulator layer 121... Sensing part 122... Connecting part 200... Alternating current generating part 300... Detecting part α, α1, α2, α', α '1, α'2, β... current loop, D1, D2... distance

Claims (10)

a magnetic sensor that senses a magnetic field by the magneto-impedance effect;
A detection unit that detects changes in the impedance of the magnetic sensor,
A magnetic sensor device in which an area of a current loop formed by wiring near the magnetic sensor is smaller than a current loop formed by wiring near the detection unit. 2. The magnetic sensor according to claim 1, wherein an inductance caused by a current loop formed by wiring near said magnetic sensor and a current loop formed by wiring near said detection unit is 50% or less of an inductance of said magnetic sensor. Device. The magnetic sensor is
a non-magnetic substrate;
a sensing circuit provided on the surface of the substrate and including a sensing portion that senses a magnetic field by magneto-impedance effect;
a first terminal portion and a second terminal portion respectively connected to both ends of the sensing circuit;
3. The magnetic sensor device according to claim 1, further comprising a conductive folding member whose one end is connected to the first terminal and folded toward the second terminal. . 4. The magnetic sensor device according to claim 3, wherein the folded member is wiring made of non-magnetic metal. A third terminal portion provided adjacent to the second terminal portion,
5. The magnetic sensor device according to claim 4, wherein the other end of said folded member is connected to said third terminal. A center-to-center distance between the second terminal portion and the third terminal portion is smaller than a center-to-center distance between the first terminal portion and the second terminal portion. The magnetic sensor device according to claim 5. 7. The magnetic sensor device according to claim 6, wherein the folding member is provided on the surface side or the back surface side of the substrate. The magnetic sensor is
a first sensing circuit including a sensing portion that senses a magnetic field by magnetoimpedance effect;
a second sensing circuit including a sensing portion that senses a magnetic field by magnetoimpedance effect,
2. The first sensing circuit and the second sensing circuit are characterized in that at least a part of the current paths overlap in a plan view, and one ends of the respective current paths are electrically connected to each other. 3. The magnetic sensor device according to 2. 9. The magnetic sensor device according to claim 8, wherein the first sensing circuit and the second sensing circuit have current directions opposite to each other in overlapping and facing portions. The magnetic sensor is
a sensing circuit including a sensing portion that senses a magnetic field by magneto-impedance effect;
a current circuit composed of a non-magnetic conductor,
3. The magnetic sensor according to claim 1, wherein at least a part of the current paths of the sensing circuit and the current circuit overlap in plan view, and one ends of each are electrically connected to each other. Device.

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