Magnetic Sensors

Abstract

To enhance sensitivity of a magnetic sensor that uses a magnetic sensitive element configured to sense a magnetic field by means of the magnetic impedance effect.SOLUTION: A magnetic sensor 200 is provided, comprising: a magnetic sensitive element 10 configured to sense a magnetic field by means of the magnetic impedance effect; and a focusing member 20 provided opposite the magnetic sensitive element 10, made of a soft magnetic material, and configured to focus magnetic field lines from the outside onto the magnetic sensitive element 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a magnetic sensor. [Background technology]

[0002] The prior art described in the publication includes a magneto-impedance effect element that includes a thin-film magnet made of a hard magnetic film formed on a non-magnetic substrate, an insulating layer covering the thin-film magnet, and a magnetic sensing part made of one or more rectangular soft magnetic films that have been given uniaxial anisotropy and are formed on the insulating layer (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-249406 A Summary of the Invention [Problem to be solved by the invention]

[0004] A magnetic sensor using a sensing element that senses a magnetic field by the magneto-impedance effect is required to have high sensitivity to changes in the magnetic field. An object of the present invention is to improve the sensitivity of a magnetic sensor that uses a sensing element that senses a magnetic field by the magneto-impedance effect. [Means for solving the problem]

[0005] The magnetic sensor to which the present invention is applied comprises a sensing element having a sensing circuit provided on a substrate, the sensing element sensing a magnetic field by the sensing circuit through the magnetic impedance effect, a focusing member which is a member separate from the sensing element and disposed opposite the sensing element, made of a soft magnetic material, and focusing magnetic field lines from the outside on the sensing element, a dissipating member which is a member separate from the sensing element and the focusing member, disposed opposite the sensing element from the side opposite to the side opposite to the focusing member, made of a soft magnetic material, and dissipating magnetic field lines that have passed through the sensing element to the outside, and a bias magnetic field applying member which is in contact with either the focusing member or the dissipating member, but not in contact with the other of the focusing member or the dissipating member, and applies a bias magnetic field to the sensing element via the focusing member and the diverging member. The focusing member has a facing portion facing the sensing element and a wide portion provided on the side where the magnetic field lines enter from the outside and whose width in a direction intersecting with the direction of the external magnetic field lines is wider on both sides than the facing portion. , The diverging member has an opposing portion facing the sensing element, and a wide portion provided on the side where magnetic field lines emerge to the outside, the wide portion having a width wider on both sides than the opposing portion in a direction intersecting the direction of the external magnetic field lines, and the bias magnetic field application member is in contact with either the portion of the wide portion of the focusing member that extends to one side of the opposing portion or the portion of the wide portion of the diverging member that extends to one side of the opposing portion, and faces the other of the portion of the wide portion of the focusing member that extends to one side of the opposing portion or the portion of the wide portion of the diverging member that extends to one side of the opposing portion.

[0007] The magnetic sensor to which the present invention is applied has a sensing circuit provided on a substrate, a sensing element that senses a magnetic field by the sensing circuit through the magnetic impedance effect, a focusing member that is a member separate from the sensing element and is provided facing the sensing element, made of a soft magnetic material, and focuses magnetic lines of force from the outside onto the sensing element, and a focusing member that is a member separate from the sensing element and the focusing member, provided facing the sensing element from the opposite side to the side where the focusing member faces, made of a soft magnetic material, and focuses the magnetic lines of force that have passed through the sensing element onto the outside. a diverting member for diverging a magnetic field to a target magnetic field, and a bias magnetic field applying member for applying a bias magnetic field to the sensing element via the focusing member and the diverging member, the bias magnetic field applying member being in contact with either one of the focusing member and the diverging member but not in contact with the other of the focusing member and the diverging member, the focusing member being provided with a facing portion facing the sensing element, a wide portion provided on the side where magnetic field lines enter from the outside and having a width wider on both sides than the facing portion in a direction intersecting the direction of the external magnetic field lines, and an extension portion extending from an end of the wide portion to the sensing element side. , The diverging member is The opposing part faces the sensing element, and the magnetic field is provided on the side where the magnetic field lines are emitted to the outside. The width in the direction intersecting with the direction of the external magnetic field lines is smaller than that of the opposing part. spread out on both sides A wide portion and an extension portion extending from an end of the wide portion to a sensing element side. 、 Equipped with The bias magnetic field applying member contacts either the end of the extension portion of the focusing member on the sensing element side or the end of the extension portion of the diverging member on the sensing element side, and faces the other of the end of the extension portion of the focusing member on the sensing element side or the end of the extension portion of the diverging member on the sensing element side. Effect of the Invention

[0009] According to the present invention, it is possible to increase the sensitivity of a magnetic sensor using a sensing element that senses a magnetic field by the magneto-impedance effect. [Brief description of the drawings]

[0010] [Figure 1] 1A and 1B are diagrams illustrating a magnetic sensor to which a first embodiment is applied. [Diagram 2] 5A to 5C are diagrams illustrating another magnetic sensor to which the first embodiment is applied. [Diagram 3] 1A and 1B are diagrams illustrating an example of a sensing element, in which (a) is a plan view and (b) is a cross-sectional view taken along line IIIB-IIIB in (a). [Figure 4] 10 is a diagram illustrating the relationship between a magnetic field applied in the longitudinal direction of a sensing part of a sensing element and the impedance of the sensing element. FIG. [Diagram 5] 4A and 4B are diagrams illustrating the relationship between impedance and a magnetic field in the magnetic sensor to which the first embodiment is applied. [Figure 6] 5 is a diagram showing the sensitivity and anisotropic magnetic field of the magnetic sensor to which the first embodiment is applied. FIG. [Figure 7] 1A and 1B are diagrams illustrating modified examples of the magnetic sensor to which the first embodiment is applied, in which (a) is a magnetic sensor having focusing members and diverging members whose planar shapes are trapezoidal, and (b) is a magnetic sensor having focusing members and diverging members whose planar shapes are Y-shaped. [Figure 8] FIG. 11 is a diagram showing a magnetic sensor to which a second embodiment is applied. [Figure 9] 13A to 13C are diagrams illustrating the detection sensitivity of a magnetic sensor to which the second embodiment is applied. [Figure 10] This is a diagram explaining magnetic sensors that compare the relationship between the bias magnetic field application method and noise. (a) is a magnetic sensor equipped with a "T-shaped" focusing member and a diverging member, in which the bias magnetic field is applied by a permanent magnet, and (b) is a magnetic sensor in which the bias magnetic field is applied by a bonded magnet. [Figure 11] This is a diagram explaining noise in a magnetic sensor equipped with a "T-shaped" focusing member and a diverging member, and in which a bias magnetic field is applied by a permanent magnet. (a) is the time change of the voltage of the sensing element, and (b) is the FFT data obtained by performing a fast Fourier transform (FFT) on the time change of the voltage. [Figure 12] 1 is a diagram illustrating noise in a magnetic sensor that applies a bias magnetic field using a bonded magnet, where (a) is the time change in voltage of the sensing element 10, and (b) is FFT data obtained by subjecting the time change in voltage to a fast Fourier transform (FFT). [Figure 13] FIG. 11 is a diagram illustrating another magnetic sensor 310 to which the second embodiment is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. [First embodiment] (Magnetic sensors 200, 210) Fig. 1 is a diagram for explaining a magnetic sensor 200 to which the first embodiment is applied. As shown in Fig. 1, 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. Note that in Fig. 1, magnetic field lines are indicated by arrows.

[0012] The magnetic sensor 200 includes a sensing element 10, a focusing member 20 that focuses magnetic lines of force from the external space onto the sensing element 10, and a dissipating member 30 that dissipates the magnetic lines of force that have passed through the sensing element 10. The focusing member 20, the sensing element 10, and the dissipating member 30 are arranged in this order in the x direction. Here, the magnetic sensor 200 refers to the area surrounded by the dashed line in FIG. 1, and the other area is referred to as the external space or the outside. The same applies to other cases.

[0013] The sensitive element 10 senses a magnetic field or a change in a magnetic field in the x-direction by the magneto-impedance effect. The focusing member 20 has a facing portion 20a facing the sensing element 10 and a wide portion 20b that is wider in the y direction than the facing portion 20a. That is, the focusing member 20 has a T-shape in plan view, with the facing portion 20a being a vertical bar and the wide portion 20b being a horizontal bar. The focusing member 20 has a constant thickness in the z direction.

[0014] In the focusing member 20, the portion of the facing portion 20a facing the sensing element 10 of (y direction (width) W 20a is, for example, 4.5 mm, and the length in the x direction L 20a is, for example, 6 mm, and the width W of the wide portion 20b in the y direction is 20b is, for example, 16 mm, and the length in the x direction L 20b For example, the distance L between the facing portion 20a and the sensing element 10 is 2 mm. 20ag For example, the distance is 2 mm. Note that these values ​​are merely examples and other values ​​may be used.

[0015] The diverging member 30 has a facing portion 30a facing the sensing element 10 and a wide portion 30b that is wider in the y direction than the facing portion 30a. That is, the diverging member 30 has a T-shaped planar shape similar to the focusing member 20. The diverging member 30 has a constant thickness in the z direction.

[0016] In the dissipating member 30, the portion of the facing portion 30a facing the sensing element 10 of (y direction (width) W 30a is, for example, 4.5 mm, and the length in the x direction L 30a is, for example, 6 mm, and the width W of the wide portion 30b in the y direction is 30b is, for example, 16 mm, and the length in the x direction L 30b For example, the distance L between the facing portion 30a and the sensing element 10 is 2 mm. 30ag For example, the distance is 2 mm. Note that these values ​​are merely examples and other values ​​may be used.

[0017] In addition, magnetic sensors 200 are arranged in the x direction in the order of wide portion 20b of focusing member 20, facing portion 20a, sensing element 10, facing portion 30a of diverging member 30, and wide portion 30b. Focusing member 20 and diverging member 30 have the same T-shape in plan view and are arranged symmetrically in the x direction with respect to sensing element 10. Hereinafter, magnetic sensor 200 will be described as having a "T-shaped" focusing member 20 and diverging member 30.

[0018] 1, the facing portion 20a is provided at the center of the wide portion 20b in the y direction. However, the facing portion 20a does not have to be provided at the center of the wide portion 20b, and may be provided at the end of the wide portion 20b in the y direction or the end of the wide portion 20b in the -y direction. In other words, the focusing member 20 may have an L-shaped planar shape ("L-shaped"). The same applies to the diverging member 30.

[0019] The focusing member 20 and the diverging member 30 are made of a soft magnetic material. A soft magnetic material is a material with a small coercive force, which is easily magnetized by a magnetic field, but quickly returns to a state in which there is no magnetization or only a small magnetization when the magnetic field is removed. Here, the focusing member 20 and the diverging member 30 are made of ferrite, for example. An example of such ferrite is MnZn, with an initial magnetic permeability of 2500±25% and a saturation magnetic flux density Bs of 420 mT. The facing portion 20a and the wide portion 20b of the focusing member 20 are integrally formed, and the facing portion 30a and the wide portion 30b of the diverging member 30 are integrally formed.

[0020] As shown in FIG. 1, the magnetic field lines from the external space enter the wide portion 20b of the focusing member 20 from the left side of the paper (-x direction side), and are focused as they move from the wide portion 20b to the facing portion 20a, and exit from the facing portion 20a. The magnetic field lines that have passed through the sensing element 10 enter the facing portion 30a of the diverging member 30. The magnetic field lines diverge as they move from the facing portion 30a to the wide portion 30b, and exit from the wide portion 30b to the external space. In other words, the magnetic field lines from the external space are focused by the focusing member 20, and the magnetic flux density, which is the density of the magnetic field lines, increases, so that they pass through the sensing element 10. In FIG. 1, the magnetic field in the external space (referred to as the external magnetic field) is represented as a magnetic field H.

[0021] The diverting member 30 has the same planar shape as the focusing member 20, and is disposed symmetrically in the x direction with the sensing element 10 in between. The diverting member 30 is provided so that the magnetic field lines focused by the focusing member 20 pass through the sensing element 10 in a focused state. In other words, the provision of the diverting member 30 makes it easier for the magnetic field lines to pass through the sensing element 10 in parallel. This intensifies the magnetic field in the external space and applies it to the sensing element 10. In addition, in the magnetic sensor 200, if a predetermined sensitivity is obtained, the dissipation member 30 does not have to be provided.

[0022] As described above, the focusing member 20 is required only to focus the magnetic field lines from the external space. For this reason, the focusing member 20 has a width W 20b The width W of the facing portion 20a (+x direction side) where the concentrated magnetic lines of force emerge from the sensing element 10 is 20a The wider the better (W 20a <W 20b ). The diverting member 30 only needs to diverge the magnetic field lines to the external space. For this reason, the diverting member 30 has a width W 30a However, the width W of the wide portion 30b from which the divergent magnetic lines of force emerge is 30b The narrower the better (W 30a <W 30b ).

[0023] 1, the -x direction side of the wide portion 20b of the focusing member 20 is disposed perpendicular (90°) to the magnetic field lines from the external space that run in the x direction. However, the end of the wide portion 20b of the focusing member 20 does not have to be disposed perpendicular to the magnetic field lines from the external space, and may be disposed at an angle of 45° or more and 90° or less. The same applies to the diverging member 30.

[0024] 1, the ends of the wide portion 20b of the focusing member 20 and the wide portion 30b of the diverging member 30 in the magnetic sensor 200 in the ±y direction may be inclined obliquely toward the sensing element 10. This obliquely removed portion is a portion through which the magnetic field lines do not easily pass when the magnetic field lines are directed from the wide portion 20b to the facing portion 20a in the focusing member 20 or when the magnetic field lines are directed from the facing portion 30a to the wide portion 30b in the diverging member 30. Therefore, even if the ends of the wide portion 20b of the focusing member 20 and the wide portion 30b of the diverging member 30 in the ±y direction are inclined obliquely toward the sensing element 10, there is little effect on the characteristics of focusing or diverging the magnetic field lines.

[0025] For comparison, the sensing element 10 not including the focusing member 20 and the diverging member 30 is referred to as the magnetic sensor 100. When there is no need to distinguish between the magnetic sensors 100 and 200, they are referred to as the magnetic sensors. The same applies to the magnetic sensors described below.

[0026] FIG. 2 is a diagram illustrating another magnetic sensor 210 to which the first embodiment is applied. The magnetic sensor 210 includes a sensing element 10, a focusing member 21 that focuses magnetic lines of force from the external space onto the sensing element 10, and a dissipating member 31 that dissipates the magnetic lines of force that have passed through the sensing element 10. The focusing member 21, the sensing element 10, and the dissipating member 31 are arranged in this order in the x direction.

[0027] The sensing element 10 is similar to the sensing element 10 of the magnetic sensor 200 . The focusing member 21 includes a facing portion 21a facing the sensing element 10, a wide portion 21b that is wider in the y direction than the facing portion 21a, and extending portions 21c and 21d that extend in the x direction from both ends of the wide portion 21b. The extending portions 21c and 21d are configured in parallel with the facing portion 21a. 21 In plan view, the focusing member 21 has an E-shape with the wide portion 21b as a vertical bar and the facing portion 21a and the extending portions 21c and 21d as horizontal bars. The focusing member 21 has a constant thickness in the z direction. The facing portion 21a and the wide portion 21b are the same as the facing portion 20a and the wide portion 20b in the magnetic sensor 200.

[0028] In the focusing member 21, the portion of the facing portion 21a facing the sensing element 10 of (y direction (width) W 21a , length in x direction L 21a is the width W of the facing portion 20a of the magnetic sensor 200 20a , length in x direction L 20a The width W of the wide portion 21b in the y direction is the same as 21b , length in x direction L 21b is the width W of the wide portion 20b of the magnetic sensor 200 20b , length in x direction L 20bThe width W of the extension 21c in the y direction is the same as 21c and the width W of the extension 21d in the y direction 21d is, for example, 2 mm, and the length L of the extension 21c in the x direction is 21c and the length L of the extension 21d in the x direction 21d For example, the distance L between the facing portion 21a and the sensing element 10 is 6 mm. 21ag is the distance L between the opposing portion 20a of the focusing member 20 and the sensing element 10 in the magnetic sensor 200. 20ag It should be noted that these values ​​are merely examples and other values ​​may be used.

[0029] The diverging member 31 includes a facing portion 31a facing the sensing element 10, a wide portion 31b that is wider in the y direction than the facing portion 31a, and extension portions 31c and 31d that extend in the -x direction from both ends of the wide portion 31b. The extension portions 31c and 31d are configured parallel to the facing portion 31a. That is, the diverging member 31 has an E-shaped planar shape similar to the focusing member 21. The diverging member 31 has a constant thickness in the z direction. The facing portion 31a and the wide portion 31b are similar to the facing portion 30a and the wide portion 30b in the magnetic sensor 200.

[0030] In the diverging member 31, the portion of the facing portion 31a facing the sensing element 10 of (y direction (width) W 31a , length in x direction L 31a is the width W of the facing portion 30a of the magnetic sensor 200 30a , length in x direction L 30a The width W of the wide portion 31b in the y direction is the same as 31b , length in x direction L 31b is the width W of the wide portion 30b of the magnetic sensor 200 30b , length in x direction L 30b The width W of the extension 31c in the y direction is the same as 31c and the width W of the extension 31d in the y direction 31d is, for example, 2 mm, and the length L of the extension 31c in the x direction is 31c and the length L of the extension 31d in the x direction 31dFor example, the distance L between the facing portion 31a and the sensing element 10 is 6 mm. 31ag is the distance L between the opposing portion 30a of the diverging member 30 and the sensing element 10 in the magnetic sensor 200. 30ag It should be noted that these values ​​are merely examples and other values ​​may be used.

[0031] In addition, the magnetic sensor 210 includes the wide portion 21b of the focusing member 21, the opposing portion 21a, the sensing element 10, and the opposing portion of the diverging member 31 in the x direction. 31a , wide section 31b The focusing member 21 and the diverging member 31 have the same E-shape in plan view and are arranged symmetrically in the x direction with respect to the sensing element 10. Hereinafter, the magnetic sensor 210 will be described as having an "E-shaped" focusing member 21 and diverging member 31.

[0032] In the focusing member 21 shown in FIG. 2, the facing portion 21a is provided at the center of the wide portion 21b in the y direction, and the extending portions 21c and 21d are provided at the ends of the wide portion 21b in the ±y direction. However, the facing portion 21a may be provided shifted from the center of the wide portion 21b in the +y direction or the -y direction. Also, one of the extending portion 21c and the extending portion 21d may not be provided. That is, in the focusing member 21, the facing portion 21a may be provided at one end of the wide portion 21b, and the extending portion 21c or the extending portion 21d may be provided at the other end of the wide portion 21b. That is, the focusing member 21 may have a C-shaped planar shape ("C-shaped"). The same applies to the diverging member 31.

[0033] As shown in FIG. 2, the magnetic field lines from the external space enter the wide portion 21b of the focusing member 21 from the left side of the drawing (-x direction side), and some of the magnetic field lines are focused as they move from the wide portion 21b to the facing portion 21a, and exit from the facing portion 21a. The other part of the magnetic field lines that entered the wide portion 21b of the focusing member 21 are focused as they move to the extension portions 21c and 21d, and exit from the extension portions 21c and 21d. The magnetic field lines that exit from the facing portion 21a pass through the sensing element 10 and enter the facing portion 31a of the diverging member 31. The magnetic field lines that exit from the extension portions 21c and 21d enter the extension portions 31d and 31c of the diverging member 31. The magnetic field lines diverge as they move from the facing portion 31a and the extension portions 31c and 31d to the wide portion 31b, and exit from the wide portion 31b to the external space. That is, the magnetic lines of force from the external space are focused by the focusing member 21, and the magnetic flux density, which is the density of the magnetic lines of force, becomes large so that they pass through the sensing element 10. In addition, in Fig. 2, the magnetic field in the external space (referred to as the external magnetic field) is represented as a magnetic field H.

[0034] As described above, the focusing member 21 is required to focus the magnetic field lines from the external space to the facing portion 21a. For this reason, the focusing member 21 has a width W 21b The width W of the facing portion 21a (+x direction side) where the concentrated magnetic lines of force emerge from the sensing element 10 21a The wider the better (W 21a <W 21b ). The diverting member 31 only needs to be able to diverge the magnetic field lines into the external space. For this reason, the diverting member 31 has a width W 31a The width W of the wide portion 31b (+x direction side) from which the diverged magnetic lines of force emerge is 31b The narrower the better (W 31a <W 31b ).

[0035] In addition, the distance L0 between the facing portion 21a of the focusing member 21 and the facing portion 31a of the diverging member 31 is preferably smaller than or equal to the distance L1 between the extension portion 21c of the focusing member 21 and the extension portion 31d of the diverging member 31 and the distance L2 between the extension portion 21d of the focusing member 21 and the extension portion 31c of the diverging member 31 (L0≦L1, L2). This is because, when the distance L1 and / or the distance L2 are smaller than the distance L0, the magnetic resistance (gap) between the extension portion 21c and the extension portion 31d and / or the extension portion 21d and the extension portion 31c becomes smaller than that between the facing portion 21a and the facing portion 31a. As a result, the magnetic field lines tend to concentrate on the gap between extension portion 21c and extension portion 31d and / or between extension portion 21d and extension portion 31c, and the magnetic field applied to the sensing element 10 provided between opposing portions 21a and 31a becomes smaller.

[0036] The diverging member 31 has the same planar shape as the focusing member 21, and is disposed symmetrically in the x direction with respect to the sensing element 10. This is for the same reason as explained for the magnetic sensor 200. Therefore, if the magnetic sensor 210 can obtain a predetermined sensitivity, the diverging member 31 does not need to be provided.

[0037] In the following, when there is no need to distinguish between the focusing member 20 of the magnetic sensor 200 and the focusing member 21 of the magnetic sensor 210, they will be referred to as focusing members. Similarly, when there is no need to distinguish between the diverging member 30 of the magnetic sensor 200 and the diverging member 31 of the magnetic sensor 210, they will be referred to as diverging members. The same applies to other cases.

[0038] (Sensing element 10) Fig. 3 is a diagram for explaining an example of the sensing element 10. Fig. 3(a) is a plan view, and Fig. 3(b) is a cross-sectional view taken along line IIIB-IIIB in Fig. 3(a). In Fig. 3(a), 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. In Fig. 3(b), the horizontal direction of the paper is the x-direction, the upward direction of the paper is the z-direction, and the back direction of the paper is the y-direction.

[0039] 3(b), a cross-sectional structure of the sensing element 10 will be described. The sensing element 10 includes a substrate 11 and a sensing circuit 12 provided on the substrate 11. The planar structure of the sensor element 10 will be described with reference to the plan view of Fig. 3(a). The sensor element 10 has a rectangular planar shape, for example. The planar shape of the sensor element 10 is a few mm square. For example, the length in the x direction is 4 mm to 6 mm, and the length in the y direction is 3 mm to 5 mm. The size of the planar shape of the sensor element 10 may be other values.

[0040] The sensing circuit 12 includes a plurality of sensing parts 121, connection parts 122 that connect the sensing parts 121 in series in a zigzag manner, and terminal parts 123 provided at one end and the other end of the series-connected sensing parts 121. The sensing part 121 has a rectangular shape in plan view having a longitudinal direction and a lateral direction. The sensing part 121 shown in FIG. 3(a) has the x direction as the longitudinal direction and the y direction as the lateral direction. In FIG. 3(a), six sensing parts 121 are arranged in parallel in the y direction. The sensing part 121 is given uniaxial magnetic anisotropy in a direction intersecting the longitudinal direction, for example, in a lateral direction (width direction) perpendicular to the longitudinal direction. The direction intersecting the longitudinal direction may have an angle of more than 45° with respect to the longitudinal direction. This allows the sensing part 121 to exhibit a magneto-impedance effect. Therefore, the sensing element 10 or the sensing circuit 12 may be referred to as a magneto-impedance element.

[0041] Each sensitive portion 121 has a length in the longitudinal direction of 1 mm to 10 mm and a width in the lateral direction of 50 μm to 150 μm, for example. The thickness is 0.2 μm to 5 μm. The interval between adjacent sensitive portions 121 is 50 μm to 150 μm. The number of sensitive portions 121 is, for example, 18. The size (length, area, thickness, etc.) of each sensing portion 121, the number of sensing portions 121, the interval between the sensing portions 121, etc. may be set according to the sensing, that is, the magnitude of the magnetic field to be measured, etc. The number of sensing portions 121 may be one.

[0042] The connection portion 122 is provided between the ends of the adjacent sensing portions 121, and connects the multiple sensing portions 121 in series. In other words, the connection portion 122 is provided so as to connect the adjacent sensing portions 121 in a zigzag (meander shape). In the sensing element 10 having six sensing portions 121 shown in FIG. 3(a), there are five connection portions 122. The number of connection portions 122 varies depending on the number of sensing portions 121. For example, if there are four sensing portions 121, there are three connection portions 122. Also, if there is one sensing portion 121, there is no connection portion 122. The width of the connection portion 122 may be set depending on the current flowing through the sensing circuit 12, etc. For example, the width of the connection portion 122 may be the same as that of the sensing portion 121.

[0043] The terminal portion 123 is provided at one end and the other end of the sensing portion 121 connected in series. In FIG. 3(a), the terminal portion 123a is provided at the lower side of the paper, and the terminal portion 123b is provided at the upper side of the paper. When the terminal portions 123a and 123b are not distinguished from each other, they are referred to as the terminal portion 123. The terminal portion 123 may be of any size that can connect an electric wire. In addition, since the sensing element 10 shown in FIG. 3(a) has six sensing portions 121, the terminal portions 123a and 123b are provided on the left side of the paper. When the number of sensing portions 121 is an odd number, the two terminal portions 123a and 123b may be provided separately on the left and right sides of the paper. In addition, the sensing element 10 may be configured by being reversed left and right.

[0044] As described above, the sensing circuit 12 is configured such that the sensing parts 121 are connected in series in a zigzag manner by the connection parts 122, and a current flows from the terminal parts 123a, 123b provided at both ends. Therefore, it is referred to as the sensing circuit 12.

[0045] The substrate 11 is a substrate made of a non-magnetic material, and may be, for example, an electrically insulating oxide substrate such as glass or sapphire, a semiconductor substrate such as silicon, or a metal substrate such as aluminum, stainless steel, or a metal plated with nickel phosphorus. If the substrate 11 is a semiconductor substrate such as silicon, or a metal substrate such as aluminum, stainless steel, or a metal plated with nickel phosphorus, and has high conductivity, an insulating layer for electrically insulating the substrate 11 from the sensing circuit 12 may be provided on the surface of the substrate 11 on the side where the sensing circuit 12 is provided. Examples of insulators constituting such an insulating layer include oxides such as SiO2, Al2O3, and TiO2, and nitrides such as Si3N4 and AlN. Here, the substrate 11 is described as being glass. In such a substrate 11, the thickness is, for example, 0.3 mm to 2 mm. The thickness may be other values.

[0046] The soft magnetic material constituting the sensing part 121 is preferably an amorphous alloy in which high melting point metals such as Nb, Ta, and W are added to an alloy mainly composed of Co. Examples of Co alloys constituting the sensing part 121 include CoNbZr, CoFeTa, and CoWZr. Such soft magnetic material constituting the sensing part 121 can be formed by a sputtering method.

[0047] The connection part 122 and the terminal part 123 in the sensing circuit 12 are formed integrally with the sensing part 121. One or both of the connection part 122 and the terminal part 123 may be made of a conductor. Examples of the conductors that constitute such connection part 122 and the terminal part 123 include Ag, Cu, Au, and Al. The connection part 122 and the terminal part 123 may be made of different conductors. If the connection part 122 and the terminal part 123 are formed integrally with the sensing part 121, it is not necessary to separately form the sensing part 121, the connection part 122, and the terminal part 123. After the connection part 122 and the terminal part 123 are formed integrally with the sensing part 121, a conductor may be layered on the connection part 122 and / or the terminal part 123.

[0048] In the above, the sensing section 121 is composed of a single layer of soft magnetic material (referred to as a soft magnetic layer). However, the soft magnetic layer may be two layers, an upper soft magnetic layer and a lower soft magnetic layer, and an antiferromagnetic coupling layer that antiferromagnetically couples the upper soft magnetic layer and the lower soft magnetic layer (AFC: Anti-Ferro-Coupling) between the upper soft magnetic layer and the lower soft magnetic layer may be provided. Examples of such antiferromagnetic coupling layers include Ru. By providing an antiferromagnetic coupling layer, the generation of a demagnetizing field is suppressed, and the sensitivity of the sensing element 10 is improved.

[0049] Furthermore, a conductive layer for reducing the electrical resistance of the sensing part 121 may be provided between the upper soft magnetic layer and the lower soft magnetic layer constituting the sensing part 121. As the conductive layer, it is preferable to use a metal or alloy having high conductivity, and it is more preferable to use a metal or alloy having high conductivity and non-magnetic. Examples of such a conductive layer include metals such as aluminum, copper, and silver. The thickness of the conductive layer is, for example, 10 nm to 500 nm. By providing the conductive layer, the frequency of the alternating current flowing through the sensing circuit 12 can be increased.

[0050] Furthermore, a magnetic domain suppression layer for suppressing the generation of closure domains in the upper and lower soft magnetic layers may be provided between the upper and lower soft magnetic layers constituting the sensing part 121. Examples of such a magnetic domain suppression layer include non-magnetic materials such as Ru and SiO2, and non-magnetic amorphous metals such as CrTi, AlTi, CrB, CrTa, and CoW. By providing the magnetic domain suppression layer to suppress the generation of closure domains in the sensing part 121, the generation of noise due to the so-called Barkhausen effect caused by the movement of domain walls is suppressed.

[0051] The soft magnetic layer constituting the sensing section 121 may be multi-layered, more than two layers, with an antiferromagnetic coupling layer, a conductive layer, or a magnetic domain suppression layer provided between each layer. Also, two or all of the above antiferromagnetic coupling layers, conductive layers, and magnetic domain suppression layers may be used in combination.

[0052] (Function of sensing element 10) Next, the operation of the sensing element 10 will be described. Fig. 4 is a diagram for explaining the relationship between the magnetic field H applied in the longitudinal direction of the sensing part 121 of the sensing element 10 and the impedance Z of the sensing element 10. In Fig. 4, the horizontal axis is the magnetic field H, and the vertical axis is the impedance Z. The impedance Z is measured by passing an AC current between the terminals 123a and 123b of the sensing circuit 12 shown in Fig. 3(a). Therefore, although the impedance Z is the impedance of the sensing circuit 12, it will be expressed as the impedance Z of the sensing element 10.

[0053] As shown in FIG. 4, the impedance Z of the sensing element 10 increases as the magnetic field H applied in the longitudinal direction of the sensing part 121 increases. The impedance Z of the sensing element 10 decreases as 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, by using 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 extracted 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. In other words, the change amount (ΔH) of 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 sensitivity is the part where the change amount ΔZ in impedance Z is the steepest (ΔZ / ΔH is the largest), that is, the change amount Zmax in impedance per unit magnetic field in the magnetic field Hb, divided by the impedance Z in the magnetic field Hb (written as impedance Zb) (Zmax / Zb). The higher the sensitivity, the greater the magnetic impedance effect, and the easier it is to measure the magnetic field or changes 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 a bias magnetic field. Hereinafter, the magnetic field Hb will be written as a bias magnetic field Hb. Note that the higher the frequency of the alternating current flowing through the sensing circuit 12, the higher the sensitivity.

[0054] (Relationship between impedance Z of magnetic sensors 200 and 210 and magnetic field H) FIG. 5 is a diagram for explaining the relationship between impedance Z and magnetic field H in the magnetic sensors 200 and 210 to which the first embodiment is applied. In FIG. 5, the horizontal axis is the magnetic field H (Oe), and the vertical axis is the impedance Z (Ω). FIG. 5 shows the impedance Z when the magnetic field H is in the range of ±15 Oe. FIG. 5 also shows the magnetic sensor 200 having the "T-shaped" focusing member 20 and diverging member 30, the magnetic sensor 210 having the "E-shaped" focusing member 21 and diverging member 31, and, for comparison, the magnetic sensor 100 configured with the sensing element 10 without the focusing member and diverging member. In the following, magnetic sensor 200 having a "T-shaped" focusing member 20 and diverging member 30 will be referred to as magnetic sensor 200 ("T-type"), magnetic sensor 210 having an "E-shaped" focusing member 21 and diverging member 31 will be referred to as magnetic sensor 210 ("E-type"), and magnetic sensor 100 consisting of a sensing element 10 without a focusing member and a diverging member will be referred to as magnetic sensor 100 ("none"). In Figure 5, magnetic sensor 200 ("T-type") will be referred to as "T-type", magnetic sensor 210 ("E-type") will be referred to as "E-type", and magnetic sensor 100 ("none") will be referred to as "none". The same applies to other figures.

[0055] Compared to magnetic sensor 100 ("None"), magnetic sensor 200 ("T-type") and magnetic sensor 210 ("E-type") have a smaller anisotropic magnetic field Hk (see FIG. 4), and the change in impedance Z with respect to the magnetic field H is steeper. Note that magnetic sensor 200 ("T-type") has a smaller anisotropic magnetic field Hk, and the change in impedance Z with respect to the magnetic field H is steeper, compared to magnetic sensor 210 ("E-type").

[0056] Fig. 6 is a diagram showing the sensitivity Zmax / Zb and anisotropic magnetic field Hk of the magnetic sensors 200 and 210 to which the first embodiment is applied. The vertical axis on the left side is the sensitivity Zmax / Zb ( / Oe), and the vertical axis on the right side is the anisotropic magnetic field Hk (Oe). Fig. 6 shows the values ​​of the sensitivity Zmax / Zb and the anisotropic magnetic field Hk extracted from the relationship between the impedance Z and the magnetic field H shown in Fig. 5. In addition to the magnetic sensor 200 ("T type") and the magnetic sensor 210 ("E type"), Fig. 6 also shows the magnetic sensor 100 ("none") for comparison.

[0057] 6, magnetic sensor 200 ("T-type") and magnetic sensor 210 ("E-type") have a smaller anisotropic magnetic field Hk and improved sensitivity Zmax / Zb compared to magnetic sensor 100 ("None"). It can also be seen that magnetic sensor 200 ("T-type") has a smaller anisotropic magnetic field Hk and improved sensitivity Zmax / Zb compared to magnetic sensor 210 ("E-type").

[0058] This is believed to be because, as in the magnetic sensors 200 and 210, the sensing element 10 includes a focusing member and a dispersing member, the magnetic flux density passing through the sensing element 10 increases, and the magnetic field applied to the sensing element 10 becomes stronger.

[0059] Fig. 7 is a diagram illustrating a modified example of the magnetic sensor 200 to which the first embodiment is applied. Fig. 7(a) shows a magnetic sensor 220 including focusing member 22 and diverging member 32 each having a trapezoidal planar shape, and Fig. 7(b) shows a magnetic sensor 230 including focusing member 23 and diverging member 33 each having a Y-shape planar shape.

[0060] As shown in FIG. 7(a), the magnetic sensor 220 is obtained by replacing the focusing member 20 and diverging member 30, which have a T-shaped planar shape in the magnetic sensor 200 ("T-shaped"), with focusing member 22 and diverging member 32, which have a trapezoidal planar shape. Therefore, the magnetic sensor 220 is referred to as the magnetic sensor 220 ("trapezoidal type"). The focusing member 22 is disposed such that the lower base side of the trapezoid is on the side where the magnetic field lines enter from the external space in the -x direction, and the upper base side of the trapezoid is disposed on the side facing the sensing element 10. In the focusing member 22, the width W in the y direction of the upper base facing the sensing element 10 is 22a is the width W in the y direction of the bottom where the magnetic field lines enter from the outside space 22b is smaller than (W 22a <W 22b Similarly, the diverting member 32 is disposed such that the upper base side of the trapezoid faces the sensing element 10, and the lower base side of the trapezoid faces the side where the magnetic field lines emerge in the +x direction into the external space. 32a is the width W in the y direction of the bottom where the magnetic field lines emerge into the external space 32bis smaller than (W 32a <W 32b ). In other words, focusing member 22 and diverging member 32 are arranged symmetrically in the x direction with sensing element 10 in between. In this way, focusing member 22 focuses the magnetic field lines entering from the external space onto sensing element 10. Also, diverging member 32 diverges the magnetic field lines that have passed through sensing element 10. Magnetic sensor 220 ("trapezoidal type") has smaller magnetic resistance of focusing member and diverging member than magnetic sensor 200 ("T type"). Note that the planar shapes of focusing member 22 and diverging member 32 of magnetic sensor 220 ("trapezoidal type") do not have to be symmetrical in the y direction.

[0061] As shown in FIG. 7(b), magnetic sensor 230 is obtained by replacing focusing member 20 and diverging member 30, which have a T-shaped planar shape in magnetic sensor 200 ("T-type"), with focusing member 23 and diverging member 33, which have a Y-shaped planar shape. Therefore, magnetic sensor 230 is referred to as magnetic sensor 230 ("Y-type"). Focusing member 23 is arranged with the wider part of the Y shape on the side where magnetic field lines enter from the external space in the -x direction, and the narrower part of the Y shape on the side facing sensing element 10. In focusing member 23, width W in the y direction on the side facing sensing element 10 is 23a is the width W in the y direction on the side where the magnetic field lines enter from the outside space 23b is smaller than (W 23a <W 23b Similarly, the diverging member 33 is arranged such that the narrowed portion of the Y shape faces the sensing element 10, and the widened portion of the Y shape faces the outside space in the +x direction, where the magnetic field lines emerge. 33a is the width W in the y direction on the side where the magnetic field lines emerge into the external space 33b is smaller than (W 33a <W 33b). That is, focusing member 23 and diverging member 33 are arranged symmetrically in the x direction with sensing element 10 in between. In this way, focusing member 23 focuses the magnetic field lines entering from the external space onto sensing element 10. Also, diverging member 33 diverges the magnetic field lines that have passed through sensing element 10. Note that the focusing member 23 and diverging member 33 in magnetic sensor 230 ("Y-shaped") may have only one widened portion of the Y shape. Also, focusing member 23 and diverging member 33 may have a V-shaped planar shape.

[0062] As described above, the focusing member focuses the magnetic field lines from the external magnetic field, increases the magnetic flux density, and transmits the magnetic field lines through the sensing element 10. The diverging member diverges the magnetic field lines that have transmitted through the sensing element 10 and sends them out to the outside. Therefore, as shown in the focusing member 22 of the magnetic sensor 220 in FIG. 7(a) and the focusing member 23 of the magnetic sensor 230 in FIG. 7(b), the focusing member may be any member that focuses the magnetic field lines from the external magnetic field. Also, as shown in the diverging member 32 of the magnetic sensor 220 in FIG. 7(a) and the diverging member 33 of the magnetic sensor 230 in FIG. 7(b), the diverging member may be any member that diverges the magnetic field lines into the external space.

[0063] For this purpose, the focusing member only needs to have a width on the side where the magnetic field lines enter from the external space, i.e., the side farther from the sensing element 10, that is wider than the width on the side of the sensing element 10. Similarly, the diverging member only needs to have a width on the side where the magnetic field lines exit into the external space, i.e., the side farther from the sensing element 10, that is wider than the width on the side of the sensing element 10.

[0064] [Second embodiment] In the first embodiment, the bias magnetic field Hb applied to the sensing element 10 is superimposed on an external magnetic field from an external space. In the second embodiment, the bias magnetic field Hb is applied by a permanent magnet provided in the vicinity of or in contact with either or both of the focusing member and the diverging member.

[0065] FIG. 8 is a diagram showing a magnetic sensor 300 to which the second embodiment is applied. The magnetic sensor 300 includes the magnetic sensor 200 shown in FIG. 1 and a permanent magnet 40. Therefore, the same parts as those in the magnetic sensor 200 shown in FIG. 1 are denoted by the same reference numerals and description thereof will be omitted. For example, a disk-shaped permanent magnet can be used as the permanent magnet 40. For example, a ferrite magnet having a diameter of 1 mm to 5 mm and a thickness of 0.1 mm to 2 mm can be used as such a permanent magnet 40. The permanent magnet 40 is an example of a bias magnetic field applying member.

[0066] In the magnetic sensor 300, the permanent magnet 40 is provided in contact with the sensing element 10 side of the end portion in the -y direction of the wide portion 20b of the focusing member 20. The position where the permanent magnet 40 is provided is referred to as position A (in FIG. 8, this is indicated as [A], and the same applies to other positions). At this time, the permanent magnet 40 is arranged so that its N pole faces the wide portion 20b side of the focusing member 20. As shown by the thick arrows, the magnetic field lines emanating from the north pole of the permanent magnet 40 pass from the wide portion 20b of the focusing member 20 to the facing portion 20a, and then pass through the sensing element 10. The magnetic field lines that have passed through the sensing element 10 then pass from the facing portion 30a of the diverting member 30 to the wide portion 30b, and then return to the south pole of the permanent magnet 40. In other words, the magnetic field lines from the permanent magnet 40 pass through the focusing member 20 and the diverting member 30, and then pass through the sensing element 10. of By passing through, a bias magnetic field Hb is applied to the sensitive element 10 .

[0067] In addition, in the magnetic sensor 300 ("T-type+permanent magnet"), the magnetic field lines travel a distance L3 when returning from the wide portion 30b of the dissipation member 30 to the permanent magnet 40.

[0068] In addition to being located at position A, the permanent magnet 40 may be located at the +y-direction end of the wide portion 20b of the focusing member 20 on the side facing the sensing element 10 (position B), at the -y-direction end of the wide portion 30b of the diverging member 30 on the side facing the sensing element 10 (position C), or at the +y-direction end on the side facing the sensing element 10 (position D). Also, the permanent magnet 40 may be provided at the end (position E) of the wide portion 20b of the focusing member 20 in the -y direction. Furthermore, the permanent magnet 40 may be provided at the end (position F) of the wide portion 20b of the focusing member 20 in the -y direction on the side opposite to the sensing element 10, or at a portion (position G) on the side of the wide portion 20b of the focusing member 20 on the sensing element 10 side and close to the facing portion 20a. Positions A to G shown here are examples, and the permanent magnet 40 may be provided at a portion other than positions A to G. Also, multiple permanent magnets 40 may be provided at multiple positions (positions A to G, etc.). The multiple permanent magnets 40 used in this case may have the same performance or may have different performance. As in the case where the permanent magnet 40 is provided at position A shown in FIG. 8, the permanent magnet 40 may be arranged so that the magnetic field lines from the permanent magnet 40 pass through the sensing element 10 to apply the bias magnetic field Hb.

[0069] Fig. 9 is a diagram for explaining the detection sensitivity of the magnetic sensor 300 to which the second embodiment is applied. The horizontal axis is AC voltage (V), and the vertical axis is detection sensitivity (mV / nT). Here, the magnetic sensor 300 is expressed as magnetic sensor 300 ("T-type + permanent magnet"), and in Fig. 9, it is expressed as "T-type + permanent magnet". And Fig. 9 shows the magnetic sensor 100 ("none") in addition to the magnetic sensor 300 ("T-type + permanent magnet").

[0070] The detection sensitivity is the voltage of the sensing element 10 per unit magnetic field when a magnetic sensor (magnetic sensor 300 ("T-type + permanent magnet"), magnetic sensor 100) is placed in an AM modulation circuit and an AC voltage is applied.

[0071] As shown in FIG. 9, the detection sensitivity of the magnetic sensor 300 ("T-type + permanent magnet") is improved by more than two times compared to the magnetic sensor 100 ("none").

[0072] In addition, the noise density was 38 pT / √Hz for the Magnetic Sensor 100 ("none"), while it was 12.4 pT / √Hz for the Magnetic Sensor 300 ("T-type + permanent magnet"), an improvement of nearly three times.

[0073] Fig. 10 is a diagram illustrating magnetic sensors comparing the relationship between the method of applying the bias magnetic field Hb and noise. Fig. 10(a) shows a magnetic sensor 300 equipped with a "T-shaped" focusing member 20 and a diverging member 30, in which the bias magnetic field Hb is applied by a permanent magnet 40, and Fig. 10(b) shows a magnetic sensor 400 in which the bias magnetic field Hb is applied by a bonded magnet 50.

[0074] FIG. 10(a) shows the magnetic sensor 300 ("T-type+permanent magnet") shown in FIG. The magnetic sensor 400 in FIG. 10(b) includes a sensing element 10 and bonded magnets 50a and 50b. The bonded magnets 50a and 50b are arranged in the y direction on either side of the sensing element 10. When the bonded magnets 50a and 50b are not distinguished from each other, they are referred to as bonded magnets 50. The bonded magnet 50 may also be referred to as a bonded magnet. A bonded magnet is a rod-shaped permanent magnet formed by mixing minute magnetic particles or fine powder with a binder such as resin. The magnetic sensor 400 to which a bias magnetic field Hb is applied by the bonded magnet 50 is referred to as a magnetic sensor 400 ("bonded magnet").

[0075] FIG. 11 is a diagram for explaining noise in a magnetic sensor 300 ("T-shaped + permanent magnet") that includes a "T-shaped" focusing member 20 and a diverging member 30 and applies a bias magnetic field Hb by a permanent magnet 40. FIG. 11(a) shows the time change of the voltage of the sensing element 10, and FIG. 11(b) shows FFT data obtained by performing a fast Fourier transform (FFT) on the time change of the voltage. In FIG. 11(a), the horizontal axis is time (sec) and the vertical axis is voltage (V). In FIG. 11(b), the horizontal axis is frequency (Hz) and the vertical axis is FFT data (mV / √Hz). The voltage of the sensing element 10 is the voltage of the sensing element 10 when the sensing element 10 is connected to an AM modulation circuit and an AC voltage is applied. In FIG. 11(a), four measurement results are shown overlapping each other. FIG. 11(b) shows one of the four measurements.

[0076] FIG. 12 is a diagram explaining noise in a magnetic sensor 400 ("bonded magnet") that applies a bias magnetic field Hb by a bonded magnet 50. FIG. 12(a) shows the time change in the voltage of the sensing element 10, and FIG. 12(b) shows FFT data obtained by performing a fast Fourier transform (FFT) on the time change in voltage. In FIG. 12(a), the horizontal axis is time (sec) and the vertical axis is voltage (V). In FIG. 12(b), the horizontal axis is frequency (Hz) and the vertical axis is FFT data (mV / √Hz). The voltage of the sensing element 10 is the same as that of the magnetic sensor 300. In FIG. 12(a), four measurement results are shown overlapping each other. FIG. 12(b) shows one of the four measurements.

[0077] The magnetic sensor 300 ("T-type + permanent magnet") shown in FIG. 11(a) has less fluctuation (swell) in voltage over time compared to the magnetic sensor 400 ("bonded magnet") shown in FIG. 12(a). In other words, the magnetic sensor 300 ("T-type + permanent magnet") suppresses the generation of swell-type noise in voltage over time compared to the magnetic sensor 400 ("bonded magnet"). The magnetic sensor 300 ("T-type + permanent magnet") shown in FIG. 11(a) has a more stable voltage fluctuation (swell) compared to the magnetic sensor 400 ("bonded magnet") shown in FIG. 12(a). Pressure Obtained.

[0078] Furthermore, the magnetic sensor 300 ("T-type + permanent magnet") shown in FIG. 11(b) has less fluctuation in FFT data at frequencies from 10 Hz to 100 Hz compared to the magnetic sensor 400 ("bonded magnet") shown in FIG. 12(b). In particular, the magnetic sensor 300 ("T-type + permanent magnet") shown in FIG. 11(b) suppresses the noise that appeared around 30 Hz in the magnetic sensor 400 ("bonded magnet") shown in FIG. 12(b). This is believed to be because the thermal capacity of the focusing member 20 and the diverging member 30 in the magnetic sensor 300 ("T-type + permanent magnet") is larger and more stable than that of the bonded magnet 50.

[0079] In magnetic sensor 400 ("bonded magnet"), magnetic field lines from bonded magnet 50 tend to exit into external space. In contrast, magnetic sensor 300 ("T-type + permanent magnet") has focusing member 20 and diverging member 30, and applies bias magnetic field Hb by permanent magnet 40, so that magnetic field lines generated from permanent magnet 40 tend to be trapped within the focusing member and diverging member. On the other hand, it is believed that in bonded magnet 50, magnetic field lines tend to exit into external space, and bias magnetic field Hb tends to fluctuate. Therefore, it is believed that magnetic sensor 300 ("T-type + permanent magnet") generates less noise than magnetic sensor 400 ("bonded magnet").

[0080] However, in the magnetic sensor 300 ("T-type + permanent magnet"), when the permanent magnet 40 was placed at position E in Fig. 8, a larger noise was generated as shown in Fig. 11(a) and (b). This is thought to be because the magnetic field lines generated from the permanent magnet 40 are likely to be emitted not only within the converging member 20 and the diverging member 30 but also into the external space.

[0081] FIG. 13 is a diagram for explaining another magnetic sensor 310 to which the second embodiment is applied. The magnetic sensor 310 includes the magnetic sensor 210 ("E-type") and the permanent magnet 40 shown in FIG. 2. Therefore, the same parts as the magnetic sensor 210 ("E-type") shown in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted. As the permanent magnet 40, for example, a disk-shaped permanent magnet can be used, as in the magnetic sensor 300 ("T-type+permanent magnet"). Therefore, the permanent magnet is referred to as the permanent magnet 40. And the magnetic sensor 310 is referred to as the magnetic sensor 310 ("E-type+permanent magnet").

[0082] In the magnetic sensor 310, the permanent magnet 40 is provided in contact with the end (position I) on the +x direction side of the extension 21c of the focusing member 21. At this time, the permanent magnet 40 is provided so that the N pole faces the extension 21c side of the focusing member 21. As shown by the thick arrow, the magnetic field lines emitted from the N pole of the permanent magnet 40 pass through the extension 21c, wide portion 21b, and opposing portion 21a of the focusing member 21, and penetrate the sensing element 10. Then, the magnetic field lines that have penetrated the sensing element 10 return to the S pole of the permanent magnet 40 through the opposing portion 31a, wide portion 31b, and extension 31d of the diverting member 31. In other words, the magnetic field lines from the permanent magnet 40 pass through the focusing member 21 and the diverting member 31, and penetrate the sensing element 10. of As a result of the transmission, a bias magnetic field Hb is applied to the sensing element 10 .

[0083] In addition to position I, the permanent magnet 40 is located at the +x direction end of the extension 21d of the focusing member 21 (position J), the −x direction end of the extension 31c of the diverging member 31 (position K), 31 The magnets 40 may be provided at any one of the -x direction end portions (position M) of the extending portion 31d. Note that positions I to M are merely examples, and the magnets 40 may be provided at other positions. A plurality of permanent magnets 40 may be provided at a plurality of positions (positions I to M, etc.).

[0084] In addition, the magnetic sensor 310 ("E-type+permanent magnet") shown in FIG. 13 includes extensions 21c and 21d in focusing member 21, and extensions 31c and 31d in diverging member 31. Extension 21c of focusing member 21 faces extension 31d of diverging member 31. Similarly, extension 21d of focusing member 21 faces extension 31c of diverging member 31. Therefore, as shown in FIG. 13, the magnetic field lines travel a distance L4 when returning from extension 31d of diverging member 31 to permanent magnet 40.

[0085] On the other hand, in the magnetic sensor 300 ("T-shaped + permanent magnet") shown in FIG. 8, when the magnetic flux lines return from the wide portion 30b of the diverging member 30 to the permanent magnet 40, they pass through the distance L3. Since the magnetic sensor 310 ("E-shaped + permanent magnet") includes the extending portions 31d in the diverging member 31, the distance L4 is shorter than the distance L3 (L4 < L3). Therefore, in the magnetic sensor 310 ("E-shaped + permanent magnet"), the magnetic flux lines returning to the permanent magnet 40 are less likely to leak into the external space compared to the magnetic sensor 300 ("T-shaped + permanent magnet"). That is, the magnetic sensor 310 ("E-shaped + permanent magnet") is more likely to suppress the generation of noise compared to the magnetic sensor 300 ("T-shaped + permanent magnet").

[0086] In addition, the magnetic field strength of the sensing element 10 portion was analyzed by electromagnetic field analysis for the magnetic sensor 300 ("T-shaped + permanent magnet") and the magnetic sensor 310 ("E-shaped + permanent magnet"). Here, the planar shape of the magnetic sensor 300 ("T-shaped + permanent magnet") was set as the shape excluding the extending portions 21c, 21d of the focusing member 21 and the extending portions 31c, 31d of the diverging member 31 in the magnetic sensor 310 ("E-shaped + permanent magnet"). Then, the magnetic field strength at the sensing element 10 was 2.78 times that of the magnetic sensor 100 ("none") without the focusing member and the diverging member in the magnetic sensor 300 ("T-shaped + permanent magnet"), and 2.25 times that in the magnetic sensor 310 ("E-shaped + permanent magnet").

[0087] This is considered to be because in the magnetic sensor 300 ("T-shaped + permanent magnet"), the magnetic flux lines converge on the opposing portions 20a, 30a, while in the magnetic sensor 310 ("E-shaped + permanent magnet"), the magnetic flux lines converge not only on the opposing portions 21a, 31a but also on the extending portions 21c, 21d, 31c, 31d (see FIGS. 1 and 2).

[0088] However, when a plurality of magnetic sensors are arranged and used, the bias magnetic field Hb used for each magnetic sensor may affect other magnetic sensors in which the bias magnetic fields Hb are arranged. In such a case, it is preferable to use the magnetic sensor 310 ("E-shaped + permanent magnet") in which the bias magnetic field Hb is less likely to leak.

[0089] In addition, in magnetic sensor 300 ("T-type + permanent magnet") and magnetic sensor 310 ("E-type + permanent magnet"), the permanent magnet 40 is arranged in contact with the focusing member and / or the diverging member, but the permanent magnet 40 may be arranged in close proximity to the focusing member and / or the diverging member. Furthermore, the permanent magnet 40 that applies the bias magnetic field Hb to the sensing element 10 may be arranged in close proximity to or in contact with the focusing member 22 and / or diverging member 32 of the magnetic sensor 220 shown in Figure 7(a) whose planar shape is trapezoidal, or may be arranged in close proximity to or in contact with the focusing member 23 and / or diverging member 33 of the magnetic sensor 230 shown in Figure 7(b) whose planar shape is Y-shaped.

[0090] Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. The focusing member and the diverging member shown in each of the magnetic sensors 200, 210, 220, 230, 300, and 310 to which the present embodiment is applied may be used in combination. In other words, various modifications and combinations may be made as long as they are not contrary to the spirit of the present invention. [Explanation of symbols]

[0091] 10...sensing element, 11...substrate, 12...sensing circuit, 20, 21, 22, 23...focusing member, 20a, 21a, 30a, 31a...opposing portion, 20b, 21b, 30b, 31b...wide portion, 21c, 21d, 31c, 31d...extending portion, 30, 31, 32, 33...diverging member, 40...permanent magnet, 50, 50a, 50b...bonded magnet, 100, 200, 210, 220, 230, 300, 310, 400...magnetic sensor, 121...sensing portion, 122...connecting portion, 123, 123a, 123b...terminal portion, H...magnetic field, Hb...bias magnetic field, Hk...anisotropic magnetic field, Z...impedance

Claims

1. a sensing element having a sensing circuit provided on a substrate, the sensing circuit sensing a magnetic field by a magneto-impedance effect; A focusing member that is a member separate from the sensing element, is provided opposite the sensing element, is made of a soft magnetic material, and focuses magnetic lines of force from the outside onto the sensing element; a dissipation member that is a member separate from the sensing element and the focusing member, that is disposed opposite the sensing element from the side opposite to the side opposite to the focusing member, that is made of a soft magnetic material, and that dissipates the magnetic field lines that have passed through the sensing element to the outside; a bias magnetic field applying member that contacts one of the focusing member and the diverging member and does not contact the other of the focusing member and the diverging member, and applies a bias magnetic field to the sensing element through the focusing member and the diverging member; The focusing member is The sensor includes a facing portion facing the sensing element, and a wide portion provided on the side where magnetic lines of force enter from the outside, the wide portion having a width wider on both sides than the facing portion in a direction intersecting with the direction of the external magnetic lines of force, The diverging member is The sensor includes a facing portion facing the sensing element, and a wide portion provided on the side where magnetic field lines are emitted to the outside, the wide portion having a width wider than the facing portion on both sides in a direction intersecting with the direction of the external magnetic field lines, The bias magnetic field applying member is in contact with either one of the portion of the wide portion of the focusing member that spreads to one side of the opposing portion and the portion of the wide portion of the diverging member that spreads to one side of the opposing portion, and faces the other of the portion of the wide portion of the focusing member that spreads to one side of the opposing portion and the portion of the wide portion of the diverging member that spreads to one side of the opposing portion. Magnetic sensor.

2. A sensing element comprising a sensing circuit provided on a substrate, the sensing circuit sensing a magnetic field by a magnetic impedance effect; A focusing member that is a member separate from the sensing element, is provided opposite the sensing element, is made of a soft magnetic material, and focuses magnetic lines of force from the outside onto the sensing element; a dissipation member that is a member separate from the sensing element and the focusing member, that is disposed opposite the sensing element from the side opposite to the side opposite to the focusing member, that is made of a soft magnetic material, and that dissipates the magnetic field lines that have passed through the sensing element to the outside; a bias magnetic field applying member that contacts one of the focusing member and the diverging member and does not contact the other of the focusing member and the diverging member, and applies a bias magnetic field to the sensing element through the focusing member and the diverging member; The focusing member is The sensor includes a facing portion facing the sensor element, a wide portion provided on the side where magnetic lines of force enter from the outside and having a width wider on both sides than the facing portion in a direction intersecting with the direction of the external magnetic lines of force, and an extension portion extending from an end of the wide portion toward the sensor element, The diverging member is The sensor includes a facing portion facing the sensor element, a wide portion provided on the side where magnetic field lines emerge to the outside and having a width wider on both sides than the facing portion in a direction intersecting with the direction of the external magnetic field lines, and an extension portion extending from an end of the wide portion toward the sensor element, The bias magnetic field applying member is in contact with either one of the end of the extension of the focusing member on the side of the sensitive element and the end of the extension of the diverging member on the side of the sensitive element, and faces the other of the end of the extension of the focusing member on the side of the sensitive element and the end of the extension of the diverging member on the side of the sensitive element. Magnetic sensor.

Images