magnetic sensor

Abstract

Provided is a magnetic sensor capable of detecting a weak magnetic field at a position far from a magnetic field source. The magnetic sensor (1) of the present invention includes: magnetic bodies (10, 20) disposed with their magnetic collection surfaces (11a, 21a) facing opposite directions; and a magnetic detection unit (30) that detects magnetic flux passing between the magnetic bodies (10, 20). Thus, magnetic flux collected by the magnetic collection surface (11a) of the magnetic body (10) passes through the magnetic collection surface (21a) of the magnetic body (20) via the magnetic detection unit (30), so the magnetic field diffused in space can be efficiently collected. Thus, even at a position far from a magnetic field source, the magnetic field can be collected under conditions of high uniformity.

Description

Technical Field

[0001] This invention relates to magnetic sensors, and more particularly to magnetic sensors capable of detecting weak magnetic fields from locations far from a magnetic field source. Background Technology

[0002] Patent document 1 discloses a magnetic sensor that improves detection sensitivity by using a rod-shaped magnetic body to concentrate magnetic flux on the sensor chip.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 6610178 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] However, the magnetic sensor described in Patent Document 1 requires bringing the magnet close to the magnetic field source to perform the measurement, and it is not easy to detect weak magnetic fields at locations far from the magnetic field source.

[0008] Therefore, the object of the present invention is to provide a magnetic sensor capable of detecting weak magnetic fields at locations far from a magnetic field source.

[0009] Means for solving technical problems

[0010] The magnetic sensor of the present invention is characterized by comprising: a first magnetic body and a second magnetic body arranged such that their magnetic collecting surfaces face opposite sides; and a magnetic detection unit that detects the magnetic flux passing through the first magnetic body and the second magnetic body.

[0011] According to the present invention, the magnetic flux collected from the magnetic collecting surface of the first magnetic body passes through the magnetic detection unit and then through the magnetic collecting surface of the second magnetic body, thus enabling efficient collection of magnetic fields diffused in space. Therefore, even at a great distance from the magnetic field source, magnetic collection can be performed under conditions of high magnetic field uniformity.

[0012] In this invention, the magnetic collecting surfaces of the first and second magnetic bodies can be parallel to each other. Therefore, by making the magnetic collecting surfaces of the first and second magnetic bodies perpendicular to the magnetic flux, weak magnetic fields can be detected with high sensitivity.

[0013] In this configuration, the magnetic collecting surface may extend along a first direction and a second direction perpendicular to the first direction. The first magnetic body and the second magnetic body each include a magnetic coupling portion magnetically coupled to the magnetic detection unit, and a magnetic collecting portion extending from the magnetic coupling portion along the first direction and forming the magnetic collecting surface. This allows for adjustment of the magnetic collecting efficiency by changing the size of the magnetic collecting portion. Furthermore, in this configuration, the magnetic collecting portions of the first and second magnetic bodies may extend from the magnetic coupling portion to both sides of the first direction. This further improves the magnetic collecting efficiency. Additionally, the magnetic collecting portions of the first and second magnetic bodies may have a portion extending from the magnetic coupling portion along the second direction. In this case, the magnetic collecting efficiency can also be further improved.

[0014] Invention Effects

[0015] Thus, according to the present invention, a magnetic sensor capable of detecting weak magnetic fields at locations far from a magnetic field source can be provided. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating the structure of the magnetic sensor 1 according to the first embodiment of the present invention. (a) is an xy-plane view, and (b) is a yz-plane view.

[0017] Figure 2 (a) is a schematic diagram illustrating the method for detecting the magnetic field using magnetic sensor 1. Figure 2 (b) is an enlarged view of it.

[0018] Figure 3 This is a general perspective view illustrating the structure of the magnetic sensor 2 according to the second embodiment of the present invention.

[0019] Figure 4 This is a general perspective view illustrating the structure of the magnetic sensor 2 according to the second embodiment of the present invention.

[0020] Figure 5 This is a roughly exploded perspective view showing the state in which the sensor chip constituting the magnetic detection unit 30 is separated from the magnetic bodies 10 and 20.

[0021] Figure 6 This is a general top view of the sensor chip that constitutes the magnetic detection unit 30.

[0022] Figure 7 It is along Figure 6 A rough cross-sectional view of the BB line.

[0023] Figure 8 This is a general perspective view illustrating the structure of the magnetic sensor 3 according to the third embodiment of the present invention.

[0024] Figure 9This is a general perspective view illustrating the structure of the magnetic sensor 4 according to the fourth embodiment of the present invention.

[0025] Symbol Explanation

[0026] Magnetic sensors 1-4

[0027] 10, 20 magnetic materials

[0028] 11, 21 Magnetizing section

[0029] 11a, 21a magnetic collecting surfaces

[0030] 11b, 21b Reverse side

[0031] Magnetic coupling sections 12, 22, 22a, 22b

[0032] 23 areas

[0033] 30 Magnetic Detection Department

[0034] 31 Component Forming Surface

[0035] 32 Back

[0036] 33-36 Side View

[0037] 37, 38 Insulation layer

[0038] 40 substrate

[0039] 50 Support body

[0040] A magnetic field source

[0041] G1~G4 magnetic gap

[0042] Magnetic layers M1~M3, M11, M21, M31, M12, M22, M32

[0043] R1~R4 magnetic sensitive elements

[0044] φ magnetic flux Detailed Implementation

[0045] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0046] <First Implementation Method>

[0047] Figure 1 This is a schematic diagram illustrating the structure of the magnetic sensor 1 according to the first embodiment of the present invention. (a) is an xy-plane view, and (b) is a yz-plane view.

[0048] like Figure 1As shown, the magnetic sensor 1 of the first embodiment includes magnetic bodies 10 and 20 and a magnetic detection unit 30. The magnetic bodies 10 and 20 are made of a high magnetic permeability material such as ferrite, and each has a magnetic collecting part 11 and 21 for collecting magnetic field that is the target of detection; and a magnetic coupling part 12 and 22 that are magnetically coupled to the magnetic detection unit 30 and apply the collected magnetic flux to the magnetic detection unit 30.

[0049] The magnetic collecting section 11 has a magnetic collecting surface 11a constituting the yz plane and a back surface 11b located on the opposite side thereon. The magnetic collecting section 12 has a magnetic collecting surface 21a constituting the yz plane and a back surface 21b located on the opposite side thereon. The magnetic collecting surfaces 11a and 21a face each other to opposite sides, and the back surfaces 11b and 21b face each other. Thus, the magnetic collecting surfaces 11a and 21a are parallel to each other. The magnetic detection section 30 is arranged in the x-direction between the magnetic coupling section 12 of the magnetic body 10 and the magnetic coupling section 22 of the magnetic body 20, thereby detecting the direction and intensity of the magnetic flux passing through the magnetic coupling section 12 of the magnetic body 10 and the magnetic coupling section 22 of the magnetic body 20.

[0050] Figure 2 (a) is a schematic diagram illustrating the method for detecting the magnetic field using magnetic sensor 1. Figure 2 (b) is an enlarged view of it.

[0051] like Figure 2 As shown, the magnetic sensor 1 of this embodiment detects magnetic flux φ at a location far from the magnetic field source A. At this location, although the magnetic flux density is lower than near the magnetic field source A, the magnetic field uniformity is high. The magnetic flux φ with high uniformity is collected using magnetic collecting surfaces 11a and 21a, and the collected magnetic flux φ is applied to the magnetic detection unit 30. Therefore, the magnetic field diffused in the space far from the magnetic field source A can be detected efficiently.

[0052] In this way, the magnetic sensor 1 of this embodiment uses magnetic collecting surfaces 11a and 21a facing opposite sides to collect magnetic fields that diffuse in space. Therefore, even if it is difficult to approach the magnetic field source A due to the presence of obstacles, a weak magnetic field can be detected at a position far away from the magnetic field source A.

[0053] <Second Implementation Method>

[0054] Figure 3 and Figure 4 This is a general perspective view illustrating the structure of the magnetic sensor 2 according to the second embodiment of the present invention.

[0055] like Figure 3 and Figure 4As shown, the magnetic sensor 2 of the second embodiment uses a sensor chip as the magnetic detection unit 30, and includes a substrate 40 on which the sensor chip is mounted, as well as a support 50 supporting the substrate 40 and the magnetic body 20. These aspects differ from the magnetic sensor 1 of the first embodiment. Other basic components are the same as those of the magnetic sensor 1 of the first embodiment, so the same reference numerals are used for the same elements, and repeated descriptions are omitted.

[0056] The substrate 40 has its xz plane as the main surface, on which the sensor chip constituting the magnetic detection unit 30, the magnetic coupling part 12 of the magnetic body 10, and the magnetic coupling parts 22a and 22b of the magnetic body 20 are mounted. The magnetic coupling parts 22a and 22b of the magnetic body 20 are divided into two. The support body 50 has its xy plane as the main surface, on which the substrate 40 and the magnetic body 20 are supported.

[0057] Figure 5 This is a roughly exploded perspective view showing the state in which the sensor chip constituting the magnetic detection unit 30 and the magnetic bodies 10 and 20 are separated.

[0058] like Figure 5 As shown, the sensor chip constituting the magnetic detection unit 30 has an element forming surface 31 and a back surface 32 constituting the yz plane, side surfaces 33 and 34 constituting the xy plane, and side surfaces 35 and 36 constituting the xz plane. A magnetic sensing element and magnetic body layers M1 to M3, described later, are formed on the element forming surface 31 of the sensor chip. The side surface 36 of the sensor chip is the surface facing the substrate 40.

[0059] The magnetic body 10, constituting the magnetic coupling portion 12, is a rod-shaped body with the x-direction as its long side. One end of the magnetic body 10 in the x-direction is positioned approximately at the center of the element forming surface 31 in the z-direction, covering a portion of the magnetic body layer M1. The magnetic body 20 has a region 23 extending along the x-direction. The sensor chip side end of the region 23 is divided into two parts that extend along the x-direction and have a shape that bends towards each other in the z-direction. The bent portions in the z-direction constitute the magnetic coupling portions 22a and 22b of the magnetic body 20. The magnetic coupling portions 22a and 22b respectively cover a portion of the magnetic body layers M2 and M3.

[0060] Figure 6 This is a general top view of the sensor chip that constitutes the magnetic detection unit 30. Figure 7 It is along Figure 6 A rough cross-sectional view of the BB line.

[0061] like Figure 6 and Figure 7As shown, four magnetic sensing elements R1 to R4 are formed on the element forming surface 31 of the sensor chip. There are no particular restrictions on the magnetic sensing elements R1 to R4, as long as their resistance changes according to the direction of the magnetic flux; for example, MR elements can be used. The fixed magnetization directions of the magnetic sensing elements R1 to R4 are aligned to the same direction (e.g., the positive side in the z-direction). The magnetic sensing elements R1 to R4 are covered by an insulating layer 37, and magnetic body layers M1 to M3, made of permalloy or the like, are formed on the surface of the insulating layer 37. The magnetic body layers M1 to M3 are covered by an insulating layer 38. Furthermore, one side of the magnetic body layers M1 to M3 located in the y-direction ( Figure 7 The upper part of the middle) is defined as magnetic body layers M11, M21, and M31, and the other side located in the y direction ( Figure 7 In the case where the lower part (of the magnetic material) is defined as magnetic layers M12, M22, and M32, when viewed from above (in the x-direction), magnetic element R1 is located between magnetic layers M11 and M21, magnetic element R2 is located between magnetic layers M12 and M22, magnetic element R3 is located between magnetic layers M11 and M31, and magnetic element R4 is located between magnetic layers M12 and M32. Thus, a magnetic field is applied to magnetic elements R1 to R4 through magnetic gaps G1 to G4. Here, the directions of the magnetic fields applied to magnetic elements R1 and R2 differ from the directions of the magnetic fields applied to magnetic elements R3 and R4 by 180°. Therefore, by bridging magnetic elements R1 to R4, the direction and intensity of the magnetic flux applied through the magnetic material 10 can be detected.

[0062] However, in this invention, it is not necessary to arrange each magnetic sensing element R1 to R4 between the two magnetic layers. It is sufficient to arrange each magnetic sensing element R1 to R4 near the magnetic gaps G1 to G4 formed by the two magnetic layers, i.e., on the magnetic path formed by the magnetic gaps G1 to G4. Furthermore, the width of the magnetic gaps G1 to G4 does not need to be wider than the width of the magnetic sensing elements R1 to R4; the width of the magnetic gaps G1 to G4 can be narrower than the magnetic sensing elements R1 to R4.

[0063] exist Figure 6 and Figure 7 In the diagram, the area indicated by symbol 12 represents the area covered by the magnetic coupling portion 12 of the magnetic body 10, and the areas indicated by symbols 22a and 22b represent the areas covered by the magnetic coupling portions 22a and 22b of the magnetic body 20. For example... Figure 6 and Figure 7 As shown, the magnetic coupling part 12 of the magnetic body 10 covers the magnetic body layer M1, and the magnetic coupling parts 22a and 22b of the magnetic body 20 cover the magnetic body layers M2 and M3.

[0064] With this structure, the magnetic flux collected by the magnetic collecting surface 11a of the magnetic body 10 passes through the magnetic body layers M1 to M3 and then through the magnetic collecting surface 21a of the magnetic body 20. Furthermore, since magnetic sensing elements R1 to R4 are arranged in the magnetic gaps G1 to G4 formed by the magnetic body layers M1 to M3, it is possible to efficiently detect the magnetic field diffused in the space far away from the magnetic field source A.

[0065] <Third Implementation Method>

[0066] Figure 8 This is a general perspective view illustrating the structure of the magnetic sensor 3 according to the third embodiment of the present invention.

[0067] like Figure 8 As shown, in the magnetic sensor 3 of the third embodiment, the magnetic collecting portions 11 and 21 of the magnetic bodies 10 and 20 extend to both sides in the y-direction from the magnetic coupling portions 12 and 22, which differs from the magnetic sensor 2 of the second embodiment. Other basic configurations are the same as those of the magnetic sensor 2 of the second embodiment; therefore, the same reference numerals are assigned to the same elements, and repeated descriptions are omitted.

[0068] like Figure 8 As illustrated by the magnetic sensor 2, if the magnetic collecting portions 11 and 21 of the magnetic bodies 10 and 20 are extended to both sides in the y direction, the area of ​​the magnetic collecting surfaces 11a and 21a increases, thus enabling the detection of magnetic fields diffused in the space away from the magnetic field source A with higher sensitivity.

[0069] <Fourth Implementation Method>

[0070] Figure 9 This is a general perspective view illustrating the structure of the magnetic sensor 4 according to the fourth embodiment of the present invention.

[0071] like Figure 9 As shown, in the magnetic sensor 4 of the fourth embodiment, the magnetic collecting portions 11 and 21 of the magnetic bodies 10 and 20 extend not only from the magnetic coupling portions 12 and 22 along the y-direction but also along the z-direction, which differs from the magnetic sensor 2 of the second embodiment. Other basic configurations are the same as those of the magnetic sensor 2 of the second embodiment; therefore, the same reference numerals are assigned to the same elements, and repeated descriptions are omitted.

[0072] like Figure 9 As illustrated by the magnetic sensor 4, if the width of the magnetic collecting portions 11 and 21 in the z direction of the magnetic bodies 10 and 20 is increased, the area of ​​the magnetic collecting surfaces 11a and 21a increases, thus enabling the detection of magnetic fields diffused in the space away from the magnetic field source A with higher sensitivity.

[0073] The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. Various modifications can be made without departing from the spirit of the present invention, and these modifications are also included within the scope of the present invention.

Claims

1. A magnetic sensor, characterized in that: have: The first and second magnetic bodies are arranged with their magnetic collecting surfaces facing opposite sides; and The magnetic detection unit detects the magnetic flux passing between the first magnetic body and the second magnetic body. The first magnetic body includes: a first magnetic collecting part and a first magnetic coupling part. The first magnetic collecting part has: a first magnetic collecting surface extending along a first direction and a second direction perpendicular to the first direction and with the first direction as the long side direction, and a first back surface located on the opposite side of the first magnetic collecting surface; The first magnetic coupling portion is located at the end of the first magnetic collecting portion in the first direction and protrudes upward from the first back surface in a third direction perpendicular to both the first and second directions. The second magnetic body includes: a second magnetic collecting part, a second magnetic coupling part, and a third magnetic coupling part. The second magnetic collecting part has: a second magnetic collecting surface extending along the first direction and the second direction and with the first direction as the long side direction, and a second back surface located on the opposite side of the second magnetic collecting surface; The second magnetic coupling portion and the third magnetic coupling portion are located at the ends of the second magnetic collecting portion in the first direction, and protrude upward from the second back side in the third direction. The first magnetic body and the second magnetic body are arranged such that the first back surface and the second back surface face each other, and the first magnetic collecting surface and the second magnetic collecting surface face opposite to each other. The second magnetic coupling portion includes: a first section that protrudes upward from the second rear side in the third direction; and a second section that protrudes from the first section in the second direction. The third magnetic coupling portion includes: a third section extending parallel to the first section and protruding upward from the second rear side in the third direction; and a fourth section protruding from the third section in the second direction, with its front end opposite to the front end of the second section. The magnetic detection unit has an element forming surface on which a magnetic sensitive element is disposed. The element forming surface of the magnetic detection unit extends along the first direction and the second direction in such a way that it is covered by the second interval of the first magnetic coupling unit, the second interval of the second magnetic coupling unit, and the fourth interval of the third magnetic coupling unit.

2. The magnetic sensor according to claim 1, characterized in that: The magnetic collecting surface of the first magnetic body is parallel to the magnetic collecting surface of the second magnetic body.

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