Magnetic Sensor

Abstract

[Problem] To reduce the influence of disturbance noise in a magnetic sensor having an external magnetic body around which a compensation coil is wound. [Solution] A magnetic sensor 100 includes: an external magnetic body 30 that concentrates a magnetic field to be detected on a magneto-sensitive element; and a compensation coil C. The compensation coil C has: a solenoid portion C0 wound around the periphery of the external magnetic body 30; and lead portions C1 and C2 connecting both ends of the solenoid portion C0 to respective connection pins P1, P2. The lead portion C2 is connected to the connection pin P2 via the inner diameter region of the solenoid portion C0. As a result, the second lead portion is less susceptible to acting as an antenna, thus making it possible to reduce the influence of disturbance noise.

Description

magnetic sensor

[0001] The present invention relates to a magnetic sensor, and more particularly to a magnetic sensor having an external magnetic body that concentrates magnetic flux in a magnetic sensing element and a compensation coil.

[0002] A known example of a magnetic sensor equipped with an external magnetic body and a compensation coil that collects magnetic flux in a magnetic sensing element is the magnetic sensor described in Patent Document 1. The magnetic sensor described in Patent Document 1 includes a magnetic sensing element integrated on a sensor chip, an external magnetic body, and a compensation coil wound around the external magnetic body. The magnetic field collected by the external magnetic body is applied to the magnetic sensing element, and the magnetic field applied to the magnetic sensing element is canceled by the compensation coil, thereby performing so-called closed-loop control. This ensures that the magnetic field applied to the magnetic sensing element is always kept at zero, eliminating offsets due to temperature changes and enabling accurate magnetic field measurement.

[0003] International Publication No. 2021 / 100252

[0004] However, when a compensation coil is wound around an external rod-shaped magnetic body, the lead-out portion of the compensation coil acts as an antenna, which causes a problem of susceptibility to external noise.

[0005] Therefore, an object of the present invention is to reduce the influence of disturbance noise in a magnetic sensor having an external magnetic body around which a compensation coil is wound.

[0006] The magnetic sensor according to the present invention comprises a magnetic sensing element, an external magnetic body that collects the magnetic field to be detected to the magnetic sensing element, and a compensation coil connected to first and second terminal electrodes, wherein the compensation coil includes a solenoid portion wound around the external magnetic body, a first lead-out portion located between one end of the solenoid portion and the first terminal electrode, and a second lead-out portion located between the other end of the solenoid portion and the second terminal electrode, wherein one end of the solenoid portion is located on one axial side of the external magnetic body, and the other end of the solenoid portion is located on the other axial side, the first and second terminal electrodes are located on one axial side, and the second lead-out portion is connected to the second terminal electrode via the inner diameter region of the solenoid portion.

[0007] According to the present invention, since the second lead-out portion, which has a long wiring length, is housed within the inner diameter area of ​​the solenoid portion, the second lead-out portion is less likely to act as an antenna, thereby making it possible to reduce the effects of external noise.

[0008] The magnetic sensor according to the present invention may further include a molded member including a bobbin positioned between the external magnetic body and the solenoid portion, the solenoid portion being wound around the bobbin, and the second lead-out portion being positioned between the bobbin and the solenoid portion, thereby making it possible to prevent contact between the compensation coil and the external magnetic body.

[0009] In the present invention, the first and second terminal electrodes may be first and second connection pins, respectively, and the molded member may further include a holding portion for holding the first and second connection pins, thereby reducing the number of parts and fixing the positional relationship between the first and second connection pins and the bobbin.

[0010] In the present invention, the first and second connection pins may protrude from the holding portion in a predetermined direction perpendicular to the axial direction of the external magnetic body, and the first and second lead-out portions may be fixed to portions closer to the tips of the first and second connection pins than the holding portion, which facilitates the work of connecting the first and second connection pins to the compensation coil using a solder bath.

[0011] In the present invention, the first and second connection pins may have first positioning portions that position the first and second lead-out portions in a predetermined direction, thereby making it possible to fix the positions of the first and second lead-out portions in the predetermined direction.

[0012] In the present invention, the molding member may have a second positioning portion located between the bobbin and the holding portion and positioning the first and second lead portions in a predetermined direction, which makes it easier to connect the first and second connection pins and the compensation coil using a solder bath.

[0013] In the present invention, the external magnetic body, the compensation coil, and the first and second connecting pins are fixed to a molded member to form a magnetic flux collecting module, and the sensor chip including the magnetic sensing element and the magnetic flux collecting module may be mounted on the same plane of a substrate. Use of such a magnetic flux collecting module makes assembly easier.

[0014] In the present invention, the external magnetic body has a wide portion and a narrow portion whose cross section perpendicular to the axial direction is smaller than the wide portion, the bobbin accommodates the narrow portion of the external magnetic body, the holding portion accommodates the wide portion of the external magnetic body, openings are provided on the bottom surfaces of the bobbin and holding portion facing the substrate, the wide portion of the external magnetic body protrudes from the opening in the holding portion, the narrow portion of the external magnetic body does not protrude from the opening in the bobbin, and the wide portion of the external magnetic body protruding from the opening in the holding portion may be fixed to the substrate. This allows the external magnetic body to be accurately positioned on the substrate and makes it possible to prevent contact between the external magnetic body and the compensation coil.

[0015] Thus, according to the present invention, it is possible to reduce the influence of disturbance noise in a magnetic sensor having an external magnetic body around which a compensation coil is wound.

[0016] FIG. 1 is a schematic perspective view showing the appearance of a magnetic sensor 100 according to one embodiment of the present invention. FIG. 2 is a schematic exploded perspective view of the magnetic sensor 100. FIG. 3 is a schematic perspective view showing the appearance of a magnetic sensor module 1. FIG. 4 is a schematic exploded perspective view of the magnetic sensor module 1. FIG. 5 is a schematic plan view of a sensor chip 20. FIG. 6 is a schematic cross-sectional view taken along line A-A in FIG. 5. FIG. 7 is a schematic cross-sectional view illustrating an example in which a magnetic layer and a magnetic sensing element overlap. FIG. 8 is a circuit diagram illustrating the connection between magnetic sensing elements R1 to R4 and a compensation coil C. FIG. 9 is a schematic perspective view illustrating the structure of a magnetic flux collection module 60. FIG. 10 is a schematic perspective view illustrating the structure of the magnetic flux collection module 60. FIG. 11 is a schematic exploded perspective view of the magnetic flux collection module 60 with the compensation coil C removed. FIG. 12 is a schematic exploded perspective view illustrating the magnetic flux collection module 60 with the solenoid portion C0 of the compensation coil C omitted. FIG. 13 is a schematic exploded perspective view illustrating the magnetic flux collection module 60 with the solenoid portion C0 of the compensation coil C omitted. Fig. 14 is a schematic diagram for explaining a method for fixing one end and the other end of the compensation coil C to the connection pins P1 and P2. Fig. 15 is a schematic perspective view showing the configuration of a magnetic flux collection module 60B according to a comparative example. Fig. 16 is a graph showing the frequency characteristics of noise density.

[0017] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0018] Fig. 1 is a schematic perspective view showing the appearance of a magnetic sensor 100 according to an embodiment of the present invention, and Fig. 2 is a schematic exploded perspective view of the magnetic sensor 100.

[0019] 1 and 2, the magnetic sensor 100 according to this embodiment includes a magnetic sensor module 1, which is the main body, and a lower case 2 and an upper case 3 that house the magnetic sensor module 1. The lower case 2 and the upper case 3 are made of a non-magnetic insulating material such as resin, and the magnetic sensor module 1 is housed in an internal space formed by fitting them together in the Y direction. The magnetic sensor 100 is a rod-shaped body with the Z direction as its longitudinal direction, and the end on the +Z direction side forms the sensor head. Wiring (not shown) connected to the magnetic sensor module 1 is drawn out from the end on the -Z direction side.

[0020] Fig. 3 is a schematic perspective view showing the appearance of the magnetic sensor module 1. Fig. 4 is a schematic exploded perspective view of the magnetic sensor module 1.

[0021] As shown in FIGS. 3 and 4 , the magnetic sensor module 1 includes a substrate 10, a sensor chip 20 mounted on a surface 11 of the substrate 10 that constitutes the XZ plane, an external magnetic body 40, an auxiliary chip 50, and a magnetic flux collection module 60 including an external magnetic body 30. The sensor chip 20 has an element formation surface 21 and a back surface 22 that constitute the XY plane, side surfaces 23 and 24 that constitute the YZ plane, and side surfaces 25 and 26 that constitute the XZ plane. The sensor chip 20 is mounted on the substrate 10 so that the side surface 26 faces the surface 11 of the substrate 10. A magnetic sensing element and magnetic layers M1 to M3, which will be described later, are formed on the element formation surface 21 of the sensor chip 20. As described above, in this embodiment, the surface 11 of the substrate 10 and the element formation surface 21 of the sensor chip 20 are perpendicular to each other. However, in the present invention, it is not essential that the two surfaces be perfectly perpendicular to each other; they may have a predetermined inclination relative to the perpendicular.

[0022] The external magnetic bodies 30 and 40 serve to collect magnetic flux toward the sensor chip 20 and are both made of a high-permeability material such as ferrite. The external magnetic body 30 is a rod-shaped body with its longitudinal direction in the Z direction and is positioned approximately at the center of the element forming surface 21 in the X direction so as to cover a portion of the magnetic layer M1. The external magnetic body 40 is located on the opposite side of the sensor chip 20 from the external magnetic body 30. The external magnetic body 40 has its longitudinal direction in the Z direction and includes a rod-shaped portion 41 that covers the back surface 22 of the sensor chip 20, and overhanging portions 42 and 43 that protrude from the rod-shaped portion 41 toward the element forming surface 21 to cover the side surfaces 23 and 24 of the sensor chip 20, respectively, and are bent to cover a portion of the magnetic layers M2 and M3. This configuration selectively collects magnetic fields in the Z direction, and the collected magnetic fields are applied to the sensor chip 20.

[0023] The auxiliary chip 50 serves to increase the strength of the sensor chip 20, and is attached to the back surface 22 of the sensor chip 20 using an adhesive or the like. The material of the auxiliary chip 50 may be the same as that of the sensor chip 20. Although not particularly limited, the thickness of the auxiliary chip 50 in the Z direction is greater than the thickness of the sensor chip 20 in the Z direction, thereby sufficiently increasing the mechanical strength of the sensor chip 20.

[0024] The magnetic flux collection module 60 includes a molded member 70 that houses the external magnetic body 30, and a compensation coil C wound around the molded member 70. The number of turns of the wire that makes up the compensation coil C is not particularly limited, and may be any number necessary to generate the desired canceling magnetic field. The molded member 70 is made of a non-magnetic insulating material such as resin. The structure and role of the molded member 70 will be described later.

[0025] FIG. 5 is a schematic plan view of the sensor chip 20, and FIG. 6 is a schematic cross-sectional view taken along line AA in FIG.

[0026] As shown in Figures 5 and 6, four magnetic sensing elements R1 to R4 are formed on the element formation surface 21 of the sensor chip 20. The magnetic sensing elements R1 to R4 are not particularly limited as long as they are elements whose electrical resistance changes depending on the direction of magnetic flux, and for example, MR elements can be used. The fixed magnetization directions of the magnetic sensing elements R1 to R4 are aligned in the same direction (for example, the positive side in the X direction). The magnetic sensing elements R1 to R4 are covered with an insulating layer 27, and magnetic layers M1 to M3 made of permalloy or the like are formed on the surface of the insulating layer 27. The magnetic layers M1 to M3 are covered with an insulating layer 28. If the portions of the magnetic layers M1 to M3 located on one side in the Y direction (upper side in FIG. 5) are defined as magnetic layers M11, M21, and M31, and the portions located on the other side in the Y direction (lower side in FIG. 5) are defined as magnetic layers M12, M22, and M32, then in a plan view (viewed from the Z direction), the magnetic sensing element R1 is located between the magnetic layers M11 and M21, the magnetic sensing element R2 is located between the magnetic layers M12 and M22, the magnetic sensing element R3 is located between the magnetic layers M11 and M31, and the magnetic sensing element R4 is located between the magnetic layers M12 and M32. As a result, a magnetic field passing through the magnetic gaps G1 to G4 is applied to the magnetic sensing elements R1 to R4.

[0027] However, in the present invention, it is not necessary for each magnetic sensing element R1-R4 to be located between two magnetic layers in a planar view. It is sufficient for each magnetic sensing element R1-R4 to be located near the magnetic gap G1-G4, which is made up of two magnetic layers, i.e., on the magnetic path formed by the magnetic gap G1-G4. Furthermore, the width of the magnetic gap G1-G4 does not need to be wider than the width of the magnetic sensing elements R1-R4; the width of the magnetic gap G1-G4 may be narrower than the width of the magnetic sensing elements R1-R4. In the example shown in Figure 7, the width Gx of the magnetic gap G1 in the X direction is narrower than the width Rx of the magnetic sensing element R1 in the X direction, thereby overlapping the magnetic layers M1 and M2 with the magnetic sensing element R1 when viewed from the Z direction, forming an OV. The relationship between the magnetic gaps G1-G4 and the magnetic sensing elements R1-R4 may be the relationship shown in Figure 7.

[0028] 5 and 6, the regions indicated by the reference symbols 30a and 40a indicate the regions covered by the external magnetic bodies 30 and 40, respectively. As shown in Figures 5 and 6, the external magnetic body 30 covers the magnetic body layer M1, and the external magnetic body 40 covers the magnetic body layers M2 and M3. Here, in order to more efficiently apply the magnetic field collected by the external magnetic body 30 to the magnetic sensing elements R1 to R4, it is preferable that the XY end faces of the external magnetic body 30 facing the element forming surface 21 be in contact with the insulating layer 28 on the magnetic body layer M1 directly or via an adhesive.

[0029] FIG. 8 is a circuit diagram for explaining the connection relationship between the magnetic sensing elements R1 to R4 and the compensation coil C.

[0030] As shown in FIG. 8 , the magnetic sensing element R1 is connected between the terminal electrodes T11 and T13, the magnetic sensing element R2 is connected between the terminal electrodes T12 and T14, the magnetic sensing element R3 is connected between the terminal electrodes T11 and T12, and the magnetic sensing element R4 is connected between the terminal electrodes T13 and T14. The terminal electrodes T11 to T14 are terminal electrodes that make up the terminal electrode group T10 shown in FIG. 4 . The terminal electrode group T10 is provided on the sensor chip 20 and connected to the terminal electrode group T30 shown in FIGS. 3 and 4 via wiring (not shown) formed on the substrate 10. The power supply potential Vcc is applied to the terminal electrode T11, and the ground potential GND is applied to the terminal electrode T14. Since the magnetic sensing elements R1 to R4 all have the same fixed magnetization direction, a difference occurs between the resistance change amounts of the magnetic sensing elements R1 and R2 located on one side of the external magnetic body 30 and the resistance change amounts of the magnetic sensing elements R3 and R4 located on the other side of the external magnetic body 30. As a result, the magnetic sensing elements R1 to R4 form a differential bridge circuit, and a change in the electrical resistance of the magnetic sensing elements R1 to R4 according to the magnetic flux density appears as a differential signal Va at the terminal electrodes T12 and T13.

[0031] The differential signal Va output from the terminal electrodes T12 and T13 is input to a differential amplifier 81 provided on the substrate 10 or the sensor chip 20. The output signal of the differential amplifier 81 is fed back to the terminal electrode T21. As shown in FIG. 8 , a compensation coil C is connected between the terminal electrodes T21 and T22, causing the compensation coil C to generate a canceling magnetic field corresponding to the output signal of the differential amplifier 81. The terminal electrodes T21 and T22 are connected to connection pins P1 and P2, respectively, held by the molded member 70. With this configuration, when a differential signal Va corresponding to changes in the electrical resistance of the magnetic sensing elements R1 to R4 depending on the magnetic flux density of the magnetic field to be detected appears at the terminal electrodes T12 and T13, a corresponding current flows through the compensation coil C, generating a canceling magnetic field in the opposite direction. This cancels out the magnetic field to be detected. The current output from the differential amplifier 81 is then converted into a voltage by a detection circuit 82, making it possible to detect the strength of the magnetic field to be detected. Such closed-loop control makes it possible to detect the magnetic field collected via the external magnetic bodies 30 and 40 with high accuracy.

[0032] 9 and 10 are schematic perspective views for explaining the structure of the magnetic flux collecting module 60, showing states as viewed from different angles. Also, Fig. 11 is a schematic exploded perspective view of the magnetic flux collecting module 60 in a state where the compensation coil C has been removed.

[0033] As shown in FIGS. 9 to 11 , the magnetic flux collection module 60 comprises a molded member 70, an external magnetic body 30 fixed to the molded member 70, a compensation coil C, and connection pins P1 and P2. The molded member 70 is a single member including a bobbin 71, a holding portion 72, a tip portion 73, and positioning portions 74 and 75. The bobbin 71 houses the narrow portion 31 of the external magnetic body 30, and has a tip portion 73 at its tip in the +Z direction. The tip portion 73 has a slit 73a extending in the X direction. The holding portion 72 is located on the −Z direction side of the bobbin 71, houses the wide portion 32 of the external magnetic body 30, and holds the connection pins P1 and P2 passed through a through-hole 76. The narrow portion 31 of the external magnetic body 30 has a smaller XY cross section than the wide portion 32 of the external magnetic body 30.

[0034] The connection pins P1 and P2 are terminal electrodes made of a substantially U-shaped metal member. The connection pin P1 has protrusions P1a and P1b that protrude in the +Y direction from the surface of the holding portion 72, and the connection pin P2 has protrusions P2a and P2b that protrude in the +Y direction from the surface of the holding portion 72. The protrusion P1a is a portion to which one end of the compensation coil C is connected, and the protrusion P2a is a portion to which the other end of the compensation coil C is connected. The protrusions P1a and P2a are arranged in the X direction and are located on the -Z direction side of the bobbin 71. The protrusions P1b and P2b are connected to terminal electrodes T21 and T22 shown in FIG. 8 via wiring (not shown).

[0035] 10 , portions of the XZ bottom surfaces of the bobbin 71 and the holder 72 are open, and the external magnetic body 30 is exposed from these openings. The XZ bottom surface of the wide portion 32 of the external magnetic body 30 protrudes from the holder 72 in the −Y direction, and when the magnetic flux collection module 60 is mounted on the substrate 10, the wide portion 32 of the external magnetic body 30 is fixed to the surface 11 of the substrate 10. In contrast, the XZ bottom surface of the narrow portion 31 of the external magnetic body 30 does not protrude from the bobbin 71. Although it is not necessary to provide an opening in the XZ bottom surface of the bobbin 71, providing such an opening makes it possible to attach the external magnetic body 30 to the molded member 70 from the Y direction.

[0036] A compensation coil C is wound around the bobbin 71 with its winding axis aligned in the Z direction. One end of the compensation coil C is connected to the protrusion P1a of the connection pin P1, and the other end of the compensation coil C is connected to the protrusion P2a of the connection pin P2. Positioning portions 84, 85 with locally narrow diameters are provided on the protrusions P1a, P2a, and the one and other ends of the compensation coil C are wound around these positioning portions 84, 85, respectively, and then fixed with solder. This fixes the positions in the Y direction of the one and other ends of the compensation coil C connected to the protrusions P1a, P2a. The positioning portions 84, 85 are located closer to the tips of the connection pins P1, P2 in the +Y direction than the holding portion 72. This fixes the one and other ends of the compensation coil C to portions closer to the tips of the connection pins P1, P2 in the +Y direction than the holding portion 72.

[0037] The compensation coil C includes a solenoid portion C0 wound around a bobbin 71, a lead-out portion C1 located between one end of the solenoid portion C0 and the connection pin P1, and a lead-out portion C2 located between the other end of the solenoid portion C0 and the connection pin P2. The solenoid portion C0 functions as a coil and is wound around the bobbin 71 with the Z direction as the winding axis direction. The solenoid portion C0 is wound around the bobbin 71 so that its position in the Z direction changes with each turn. In other words, if the lead-out portion C1 is the starting point and the lead-out portion C2 is the end point, the position of the wire constituting the solenoid portion C0 shifts in the +Z direction with each turn.

[0038] In this way, the compensation coil C is not wound directly around the external magnetic body 30, but is wound around the external magnetic body 30 via the bobbin 71, so the compensation coil C and the external magnetic body 30 do not come into contact with each other, which makes it possible to prevent damage to the compensation coil C or the external magnetic body 30 due to contact between the two. Here, one end of the solenoid portion C0 is located on the -Z direction side, so the wiring distance of the lead-out portion C1 is short. In contrast, the other end of the solenoid portion C0 is located on the +Z direction side, so the wiring distance of the lead-out portion C2 is long.

[0039] 12 and 13 are schematic exploded perspective views showing the magnetic flux collection module 60 with the solenoid portion C0 of the compensation coil C omitted, and are views seen from different angles.

[0040] As shown in Figures 12 and 13, the lead-out portion C2 of the compensation coil C extends substantially linearly in the Z direction and then winds around the slit 73a in the tip portion 73. When winding the compensation coil C around the bobbin 71, the wire constituting the compensation coil C is passed through the slit 73a in the tip portion 73 and then wound multiple times to form the solenoid portion C0. As a result, the lead-out portion C2 is connected to the connection pin P2 via the inner diameter region of the solenoid portion C0, rather than to the outside of the solenoid portion C0. As a result, most of the lead-out portion C2, which has a long wiring distance, is covered by the solenoid portion C0, making it less likely for the lead-out portion C2 to act as an antenna. Moreover, because the lead-out portion C2 is sandwiched between the bobbin 71 and the solenoid portion C0, the position of the lead-out portion C2 is stable.

[0041] Furthermore, the molding member 70 has positioning portions 74 and 75 located between the bobbin 71 and the holding portion 72. The positioning portion 74 is a protrusion for positioning the lead-out portion C1 of the compensation coil C and protrudes in the +X direction. The positioning portion 75 is a protrusion for positioning the lead-out portion C2 of the compensation coil C and protrudes in the -X direction. The lead-out portions C1 and C2, which extend in the Z direction, pass through the -Y direction sides of the positioning portions 74 and 75, respectively, and are connected to the connection pins P1 and P2. This restricts movement of the lead-out portions C1 and C2 in the +Y direction.

[0042] When fixing one end and the other end of the compensation coil C to the connection pins P1, P2, respectively, the ends are wound around the protrusions P1a, P2a, and then the tips of the protrusions P1a, P2a are immersed in a solder bath 90, as shown in Fig. 14. This completes the connection between one end and the other end of the compensation coil C and the connection pins P1, P2 in one go. Furthermore, when immersing the tips of the protrusions P1a, P2a in the solder bath, the movement of the lead-out portions C1, C2 of the compensation coil C in the +Y direction is restricted by the positioning portions 74, 75 of the molding member 70, so the lead-out portions C1, C2 sag and do not come into contact with the solder bath 90.

[0043] As described above, in this embodiment, after the external magnetic body 30 and the connection pins P1, P2 are fixed to the molded member 70, the compensation coil C is wound around the magnetic flux collector 60 and the connection pins P1, P2 are connected to the compensation coil C to produce the magnetic flux collector 60, and this magnetic flux collector 60 is mounted on the substrate 10, thereby enabling efficient production of the magnetic sensor module 1. Furthermore, the lead-out portion C2 of the compensation coil C included in the magnetic flux collector 60 passes through the inner diameter region of the solenoid portion C0 and is connected to the connection pin P2, making it difficult for the lead-out portion C2 to act as an antenna, thereby making it possible to reduce the effects of external noise.

[0044] Fig. 15 is a schematic perspective view showing the configuration of a magnetic flux collection module 60B according to a comparative example. The magnetic flux collection module 60B according to the comparative example differs from the magnetic flux collection module 60 shown in Fig. 9 in that the lead-out portion C2 of the compensation coil C is connected to the connection pin P2 through the radially outer side of the solenoid portion C0, rather than through the inner diameter region of the solenoid portion C0. Fig. 16 is a graph showing the frequency characteristics of noise density, where symbol A indicates the characteristics of the magnetic sensor module 1 according to this embodiment, and symbol B indicates the characteristics of a magnetic sensor module using the magnetic flux collection module 60B according to the comparative example instead of the magnetic flux collection module 60. As shown in Fig. 16, the magnetic sensor module 1 according to this embodiment has a lower noise density in the low-frequency range than the magnetic sensor module using the magnetic flux collection module 60B.

[0045] The above describes a preferred embodiment of the present invention, but the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the present invention, and it goes without saying that these modifications are also included within the scope of the present invention.

[0046] For example, in the above embodiment, both ends of the compensation coil C are connected to the connection pins P1 and P2, but it is not essential to use the connection pins P1 and P2 as terminal electrodes connected to both ends of the compensation coil C.

[0047] REFERENCE SIGNS LIST 1 magnetic sensor module 2 lower case 3 upper case 10 substrate 11 surface of substrate 20 sensor chip 21 element forming surface 22 back surface of sensor chip 23 to 26 side surface of sensor chip 27, 28 insulating layer 30, 40 external magnetic body 30a, 40a area covered by external magnetic body 31 narrow width portion 32 wide width portion 41 rod-shaped portion 42, 43 overhang portion 50 auxiliary chip 60, 60B magnetic collection module 70 molded member 71 bobbin 72 holding portion 73 tip portion 73a slit 74, 75 positioning portion 76 through hole 81 differential amplifier 82 detection circuit 84, 85 positioning portion 90 solder bath 100 magnetic sensor C compensation coil C0 solenoid portion C1, C2 lead-out portion G1 to G4 Magnetic gaps M1 to M3, M11, M21, M31, M12, M22, M32 Magnetic layers P1, P2 Connection pins P1a, P1b, P2a, P2b Protrusions R1 to R4 Magnetic sensing elements T10, T30 Terminal electrode group T11 to T14, T21, T22 Terminal electrodes

Claims

1. A magnetic sensor comprising: a magnetic sensing element; an external magnetic body that collects the magnetic field to be detected to the magnetic sensing element; and a compensation coil connected to first and second terminal electrodes, wherein the compensation coil includes a solenoid portion wound around the external magnetic body, a first lead-out portion located between one end of the solenoid portion and the first terminal electrode, and a second lead-out portion located between the other end of the solenoid portion and the second terminal electrode, wherein the one end of the solenoid portion is located on one side in the axial direction of the external magnetic body, and the other end of the solenoid portion is located on the other side in the axial direction, the first and second terminal electrodes are located on one side in the axial direction, and the second lead-out portion is connected to the second terminal electrode via an inner diameter region of the solenoid portion.

2. The magnetic sensor described in claim 1, further comprising a molded member including a bobbin positioned between the external magnetic body and the solenoid portion, the solenoid portion being wound around the bobbin, and the second lead-out portion being positioned between the bobbin and the solenoid portion.

3. The magnetic sensor according to claim 2, wherein the first and second terminal electrodes are first and second connection pins, respectively, and the molded member further includes a holding portion for holding the first and second connection pins.

4. A magnetic sensor as described in claim 3, characterized in that the first and second connection pins protrude from the holding portion in a predetermined direction perpendicular to the axial direction of the external magnetic body, and the first and second lead-out portions are fixed to portions closer to the tips of the first and second connection pins than the holding portion.

5. A magnetic sensor according to claim 4, wherein the first and second connection pins have first positioning portions that determine the positions of the first and second lead portions in the predetermined direction.

6. A magnetic sensor as described in claim 4 or 5, characterized in that the molded member has a second positioning portion located between the bobbin and the holding portion and positioning the first and second lead-out portions in the specified direction.

7. A magnetic sensor as described in any one of claims 3 to 6, characterized in that the external magnetic body, the compensation coil, and the first and second connection pins are fixed to the molded member to form a magnetic collection module, and the sensor chip including the magnetic sensing element and the magnetic collection module are mounted on the same plane of a substrate.

8. The magnetic sensor described in claim 7, characterized in that the external magnetic body has a wide portion and a narrow portion whose cross section perpendicular to the axial direction is smaller than the wide portion, the bobbin accommodates the narrow portion of the external magnetic body, the holding portion accommodates the wide portion of the external magnetic body, openings are provided on the bottom surfaces of the bobbin and holding portion facing the substrate, the wide portion of the external magnetic body protrudes from the opening of the holding portion, the narrow portion of the external magnetic body does not protrude from the opening of the bobbin, and the wide portion of the external magnetic body protruding from the opening of the holding portion is fixed to the substrate.

Images