magnetic sensor

Abstract

This invention provides a magnetic sensor that detects extremely weak magnetic fields by effectively reducing irregular noise. The magnetic sensor (1) comprises a magnetoresistive strip (S) consisting of multiple magnetoresistive elements (R) arranged in the y-direction separated by multiple hard magnetic bodies (H), and ferromagnetic films (M1, M2) arranged in the x-direction separated by a magnetic gap (G). The magnetoresistive strip (S) is disposed near the magnetic gap (G), with one end in the y-direction connected to a terminal electrode (E1) without passing through other magnetoresistive elements to which the detection magnetic field is applied, and the other end in the y-direction connected to a terminal electrode (E2) without passing through other magnetoresistive elements to which the detection magnetic field is applied. Thus, because the magnetoresistive strip (S) is a straight line without any reversal, the relationship between the direction of magnetic bias and the direction of current flow remains constant throughout the entire range. As a result, due to the significant reduction in irregular noise, extremely weak magnetic fields can be detected.

Description

Technical Field

[0001] This invention relates to magnetic sensors, and more particularly to magnetic sensors for detecting extremely weak magnetic fields. Background Technology

[0002] As a magnetic sensor, there are known magnetic sensors of the type described in Patent Document 1, which detect the orientation and intensity of a magnetic field based on changes in the resistance of a magnetoresistive element. The magnetic sensor described in Patent Document 1 ensures sufficient resistance by bending the magnetoresistive element into a meandering shape, and applies a magnetic bias to the magnetoresistive element by arranging multiple hard magnetic bodies (magnets) that divide the magnetoresistive element. If a magnetic bias is applied to the magnetoresistive element, ideally the magnetoresistive element is single-domainized, thus reducing irregular noise that overlaps with the detection signal.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 5066579 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, the magnetic sensor described in Patent Document 1 has a meandering magnetoresistive element, causing the current flowing in a certain section of the magnetoresistive element to flow in the opposite direction to the current flowing in other sections. In contrast, the direction of the magnetic bias is the same throughout the entire range of the magnetoresistive element, thus the relationship between the direction of the magnetic bias and the direction of current flow varies from section to section. As a result, irregular noise cannot be sufficiently reduced, making it difficult to detect extremely weak magnetic fields.

[0008] Therefore, the object of the present invention is to detect extremely weak magnetic fields in a magnetic sensor using a magnetoresistive element by effectively reducing irregular noise.

[0009] Methods for solving problems

[0010] The magnetic sensor of the present invention is characterized by comprising: a first magnetoresistive strip, which is composed of a plurality of magnetoresistive elements arranged in a first direction with a plurality of hard magnetic bodies imparting magnetic bias therebetween; first and second ferromagnetic films, which are arranged in a second direction intersecting the first direction with a first magnetic gap extending in the first direction apart from the first magnetic gap; and first and second terminal electrodes, wherein the first magnetoresistive strip is disposed near the first magnetic gap and a detection magnetic field is applied to it in the second direction, one end of the first magnetoresistive strip in the first direction is connected to the first terminal electrode without passing through other magnetoresistive elements to which the detection magnetic field is applied, and the other end of the first magnetoresistive strip in the first direction is connected to the second terminal electrode without passing through other magnetoresistive elements to which the detection magnetic field is applied.

[0011] According to the present invention, because the first magnetoresistive strip has a straight, non-reversible shape, the relationship between the direction of magnetic bias and the direction of current flow remains constant throughout the entire range. Therefore, even extremely weak magnetic fields can be detected without a significant reduction in irregular noise.

[0012] In this invention, the first and second ferromagnetic films may overlap with multiple magnetoresistive elements and multiple hard magnetic bodies. This allows for a more effective application of a detection magnetic field to the multiple magnetoresistive elements.

[0013] The magnetic sensor of the present invention may also further include: a first end hard magnetic body disposed at one end of the first magnetoresistive strip; and a second end hard magnetic body disposed at the other end of the first magnetoresistive strip, wherein the first and second ferromagnetic films do not overlap with the first and second end hard magnetic bodies. Therefore, the detection magnetic field collected by the first and second ferromagnetic films is not easily absorbed by the first and second end hard magnetic bodies, thus enabling a more effective application of the detection magnetic field to the first magnetoresistive strip.

[0014] In this invention, the first magnetoresistive strip may also include a low-resistance film that interconnects multiple magnetoresistive elements and has a resistance value lower than that of the magnetoresistive elements and the hard magnetic body, with a portion of the low-resistance film disposed between the magnetoresistive elements and the hard magnetic body. Thus, even when the resistance value of the hard magnetic body is high, the conductivity of the first magnetoresistive strip can be ensured, and the resistance barrier between the hard magnetic body and the magnetoresistive elements is reduced, thereby more effectively suppressing electrical irregular noise.

[0015] The magnetic sensor of the present invention may also further include: a second magnetoresistive strip, which is composed of a plurality of magnetoresistive elements arranged in a first direction with a plurality of hard magnetic bodies to which a magnetic bias is applied; a third ferromagnetic film; and a third terminal electrode. The first and third ferromagnetic films are arranged in a second direction with a second magnetic gap extending in the first direction. The second magnetoresistive strip is disposed near the second magnetic gap and is subjected to a detection magnetic field in the second direction. One end of the second magnetoresistive strip in the first direction is connected to the third terminal electrode without passing through other magnetoresistive elements to which a detection magnetic field is applied, and the other end of the second magnetoresistive strip in the first direction is connected to the first terminal electrode without passing through other magnetoresistive elements to which a detection magnetic field is applied. The directions of the current flowing in the first and second magnetoresistive strips are the same as those of each other, and the directions of the magnetic bias applied to the first and second magnetoresistive strips are the same as those of each other. Thus, the first and second magnetoresistive strips constitute a half-bridge circuit, thereby further improving the detection sensitivity.

[0016] The magnetic sensor of the present invention may also further include: a compensation coil that imparts a canceling magnetic field to the first and second magnetoresistive strips, the compensation coil comprising a first section extending along the first magnetoresistive strip in a first direction and a second section extending along the second magnetoresistive strip in the first direction, wherein the directions of the current flowing in the first section and the second section are opposite to each other. Thus, closed-loop control of the first and second magnetoresistive strips is possible.

[0017] The magnetic sensor of the present invention may also further include: third and fourth magnetoresistive strips, which are composed of a plurality of magnetoresistive elements arranged in a first direction with a plurality of hard magnetic bodies imparting magnetic bias; and a fourth terminal electrode, wherein the first and second ferromagnetic films further form a third magnetic gap extending in the first direction, and the first and third ferromagnetic films further form a fourth magnetic gap extending in the first direction, the third magnetoresistive strip is disposed near the third magnetic gap and is subjected to a detection magnetic field in the second direction, and the fourth magnetoresistive strip is disposed near the fourth magnetic gap and is subjected to a detection magnetic field in the second direction, wherein one end of the third magnetoresistive strip in the first direction is not transmitted through a magnetic field. Other magnetoresistive elements applying the detection magnetic field are connected to the third terminal electrode. The other end of the third magnetoresistive strip in the first direction is connected to the fourth terminal electrode without passing through the other magnetoresistive elements to which the detection magnetic field is applied. One end of the fourth magnetoresistive strip in the first direction is connected to the second terminal electrode without passing through the other magnetoresistive elements to which the detection magnetic field is applied. The other end of the fourth magnetoresistive strip in the first direction is connected to the fourth terminal electrode without passing through the other magnetoresistive elements to which the detection magnetic field is applied. The directions of the current flowing in the first to fourth magnetoresistive strips are the same, and the directions of the magnetic bias applied to the first to fourth magnetoresistive strips are the same. Thus, a full-bridge circuit is formed by the first to fourth magnetoresistive strips, thereby further improving the detection sensitivity.

[0018] The magnetic sensor of the present invention may also further include: a compensation coil that imparts a canceling magnetic field to the first to fourth magnetoresistive strips. The compensation coil includes a first interval extending along the first magnetoresistive strip in a first direction, a second interval extending along the second magnetoresistive strip in the first direction, a third interval extending along the third magnetoresistive strip in the first direction, and a fourth interval extending along the fourth magnetoresistive strip in the first direction. The directions of current flowing in the first and third intervals are the same, the directions of current flowing in the second and fourth intervals are the same, and the directions of current flowing in the first and second intervals are opposite. Thus, closed-loop control of the first to fourth magnetoresistive strips is possible.

[0019] The effects of the invention

[0020] Thus, according to the present invention, because irregular noise is greatly reduced, extremely weak magnetic fields can be detected. Attached Figure Description

[0021] Figure 1This is a schematic top view illustrating the structure of the magnetic sensor 1 according to the first embodiment of the present invention.

[0022] Figure 2 (a) is along Figure 1 The diagram shows a simplified cross-section of line AA. Figure 2 (b) is along Figure 1 The diagram shows a simplified cross-sectional view of the BB line.

[0023] Figure 3 This is a schematic diagram illustrating the structure of the magnetoresistive strip S in the modified example. (a) is a top view of xy and (b) is a cross-sectional view of yz.

[0024] Figure 4 This is a schematic cross-sectional view illustrating the structure of the magnetic sensor 2 according to the second embodiment of the present invention.

[0025] Figure 5 This is a schematic top view illustrating the structure of the magnetic sensor 2 according to the second embodiment of the present invention.

[0026] Figure 6 This is a schematic diagram illustrating the connection relationship between the magnetic reluctance bars S1 and S2 and the compensation coil C and the terminal electrodes E11 to E13, E15 and E16.

[0027] Figure 7 This is a schematic top view illustrating the structure of the magnetic sensor 3 according to the third embodiment of the present invention.

[0028] Figure 8 This is a schematic diagram illustrating the connection relationship between the magnetic reluctance bars S1 to S4 and the compensation coil C and the terminal electrodes E11 to E16. Detailed Implementation

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0030] <First Implementation>

[0031] Figure 1 This is a slightly top view illustrating the structure of the magnetic sensor 1 according to the first embodiment of the present invention. Furthermore, Figure 2 (a) is along Figure 1 The diagram shows a simplified cross-section of line AA. Figure 2 (b) is along Figure 1 The diagram shows a simplified cross-sectional view of the BB line.

[0032] like Figure 1 and Figure 2As shown, the magnetic sensor 1 of the first embodiment includes a magnetoresistive strip S extending in the y-direction and two ferromagnetic films M1 and M2 arranged in the x-direction. The magnetoresistive strip S is formed on the sensor substrate 11 with an insulating film 12 between it and the magnetic field. It is composed of a plurality of magnetoresistive elements R arranged in the y-direction with a plurality of hard magnetic bodies (magnets) H between them. The material of the magnetoresistive elements R is not particularly limited as long as it is a material whose resistance value changes with the orientation and strength of the magnetic field. The magnetoresistive elements R are separated in the y-direction by a plurality of hard magnetic bodies H and are effectively single-domained by a magnetic bias applied by the hard magnetic bodies H. As a result, irregular noise caused by the disorder of magnetic domains is reduced. In order to reliably single-domainize the magnetoresistive elements R, it is preferable to make the length of each magnetoresistive element R in the y-direction about a few μm.

[0033] The magnetoresistive strip S is covered by a protective film 13. Furthermore, ferromagnetic films M1 and M2 are disposed on the surface of the protective film 13. The ferromagnetic films M1 and M2 are arranged in the x-direction separated by a magnetic gap G extending in the y-direction. In this embodiment, in a top view viewed from the z-direction, the magnetic gap G overlaps with the magnetoresistive strip S. More specifically, the width of the magnetic gap G in the x-direction is narrower than the width of the magnetoresistive strip S; therefore, viewed from the z-direction, the ferromagnetic films M1 and M2 partially overlap with the magnetoresistive element R and the hard magnetic body H. Consequently, a detection magnetic field from the ferromagnetic film M1 towards the ferromagnetic film M2, or a detection magnetic field from the ferromagnetic film M2 towards the ferromagnetic film M1, is applied to the magnetoresistive strip S in the x-direction. However, in this invention, it is not necessary for the magnetic gap G and the magnetoresistive strip S to overlap in the z direction. As long as the magnetoresistive strip S is arranged near the magnetic gap G, that is, on the magnetic path formed by the magnetic gap G, and a detection magnetic field in the x direction is applied to the magnetoresistive strip S, the positional relationship between the magnetic gap G and the magnetoresistive strip S is irrelevant.

[0034] like Figure 1 As shown, one end of the magnetoresistive strip S in the y-direction is connected to terminal electrode E1, and the other end is connected to terminal electrode E2. More specifically, one end of the magnetoresistive strip S in the y-direction is connected to terminal electrode E1 without passing through any other magnetoresistive element to which the detection magnetic field is applied, and the other end of the magnetoresistive strip S in the y-direction is connected to terminal electrode E2 without passing through any other magnetoresistive element to which the detection magnetic field is applied. That is, in this embodiment, the magnetoresistive strip S is a straight line without a folding structure. Terminal electrodes E1 and E2 are connected to a detection circuit (not shown), and the detection magnetic field can be measured based on the resistance value between terminal electrodes E1 and E2.

[0035] Thus, in this embodiment, the magnetic sensor 1 has a straight shape for the magnetoresistive strip S without a folding structure. Therefore, unlike the case where the magnetoresistive strip S has a meandering folding structure, the relationship between the magnetic bias direction D and the current flow direction remains constant throughout the entire range. As a result, irregular noise is significantly reduced, enabling the detection of extremely weak magnetic fields.

[0036] Furthermore, in this embodiment, one end and the other end of the magnetoresistive strip S are respectively covered by end hard magnetic bodies H1 and H2. The end hard magnetic bodies H1 and H2 have a larger dimension in the y-direction compared to the other hard magnetic bodies H. Moreover, the ferromagnetic films M1 and M2 are positioned at a location that does not overlap with the end hard magnetic bodies H1 and H2 when viewed from the z-direction; therefore, the detection magnetic field collected by the ferromagnetic films M1 and M2 is not easily absorbed into the end hard magnetic bodies H1 and H2. Thus, a detection magnetic field can be effectively applied to the magnetoresistive strip S.

[0037] Figure 3 This is a schematic diagram illustrating the structure of the magnetoresistive strip S in the modified example. (a) is a top view of xy and (b) is a cross-sectional view of yz.

[0038] Figure 3 The illustrated magnetoresistive strip S further includes a low-resistance film 14. The low-resistance film 14 is made of a material with a low resistance value compared to the magnetoresistive element R and the hard magnetic body H. It achieves its function of reducing the resistance of the magnetoresistive strip S by interconnecting adjacent magnetoresistive elements R in the y-direction on the surface portion of the insulating film 12. Thus, the conductivity of the magnetoresistive strip S can be ensured even when the resistance value of the hard magnetic body H is high. The low-resistance film 14 is a thin film covering the surface of the insulating film 12, the side surface of the magnetoresistive element R, and the top surface. Furthermore, the hard magnetic body H is embedded in the top surface portion of the low-resistance film 14. Therefore, a portion of the low-resistance film 14 is located between the magnetoresistive element R and the hard magnetic body H, thereby reducing the resistance barrier between the magnetoresistive element R and the hard magnetic body H and more effectively suppressing electrical irregular noise.

[0039] <Second Implementation>

[0040] Figure 4 and Figure 5 These are a schematic cross-sectional view and a schematic top view, respectively, used to illustrate the structure of the magnetic sensor 2 according to the second embodiment of the present invention.

[0041] like Figure 4 and Figure 5 As shown, the magnetic sensor 2 of the second embodiment includes insulating films 22 to 25 stacked sequentially on a sensor substrate 21, a compensation coil C disposed on the surface of the insulating film 22, two magnetoresistive strips S1 and S2 disposed on the surface of the insulating film 23, and three ferromagnetic films M11 to M13 disposed on the surface of the insulating film 24.

[0042] Both magnetoresistive strips S1 and S2 are composed of multiple magnetoresistive elements R arranged in the y-direction, separated by multiple hard magnetic bodies H. The direction D of the magnetic bias applied by the hard magnetic bodies H is the same in magnetoresistive strips S1 and S2. Furthermore, ferromagnetic films M11 and M12 are arranged in the x-direction, separated by a magnetic gap G1 extending in the y-direction, and ferromagnetic films M11 and M13 are arranged in the x-direction, separated by a magnetic gap G2 extending in the y-direction. Moreover, magnetoresistive strip S1 is arranged at a position overlapping with magnetic gap G1, and magnetoresistive strip S2 is arranged at a position overlapping with magnetic gap G2.

[0043] Furthermore, the magnetic sensor 2 of this embodiment includes an external magnetic body 26 disposed on the upper surface of the sensor substrate 21, and an external magnetic body 27 covering the back and sides of the sensor substrate 21. The external magnetic bodies 26 and 27 are made of soft magnetic materials such as ferrite, and efficiently concentrate the detection magnetic field in the z-direction. The external magnetic body 26 is disposed at a position covering the ferromagnetic film M11 through the insulating film 25, thereby the detection magnetic field in the z-direction concentrated by the external magnetic body 26 is drawn into the ferromagnetic film M11 and distributed to the ferromagnetic films M12 and M13 via magnetic gaps G1 and G2. Moreover, the detection magnetic field from the ferromagnetic film M11 toward the ferromagnetic film M12 is applied to the magnetoresistive strip S1 in the -x direction, and the detection magnetic field from the ferromagnetic film M11 toward the ferromagnetic film M13 is applied to the magnetoresistive strip S2 in the +x direction. That is, the detection magnetic fields are applied to the magnetoresistive strips S1 and S2 in opposite directions.

[0044] like Figure 6 As shown, one end of the magnetoresistive strip S1 in the y-direction is connected to terminal electrode E11, and the other end is connected to terminal electrode E12. Similarly, one end of the magnetoresistive strip S2 in the y-direction is connected to terminal electrode E13, and the other end is connected to terminal electrode E11. Thus, magnetoresistive strips S1 and S2 form a half-bridge circuit. In this embodiment, terminal electrodes E11 to E13 are not connected to magnetoresistive strips S1 and S2 via other magnetoresistive elements to which the detection magnetic field is applied. Therefore, whenever current flows from terminal electrode E12 to terminal electrode E13, current flows in magnetoresistive strip S1 in the direction indicated by arrow I11, and current flows in magnetoresistive strip S2 in the direction indicated by arrow I12. In other words, current flows in magnetoresistive strips S1 and S2 in the same direction. Furthermore, since the detection magnetic fields are applied to magnetoresistive strips S1 and S2 in opposite directions, the orientation and intensity of the detection magnetic field can be determined by monitoring the potential of terminal electrode E11 using a detection circuit (not shown).

[0045] Furthermore, such as Figure 6As shown, one end of the compensation coil C is connected to terminal electrode E15, and the other end of the compensation coil C is connected to terminal electrode E16. The compensation coil C is provided to impart a canceling magnetic field to the magnetoresistive bars S1 and S2, thereby enabling so-called closed-loop control. The compensation coil C includes a section C1 extending along the y-direction of the magnetoresistive bar S1 and a section C2 extending along the y-direction of the magnetoresistive bar S2. Moreover, when current flows from terminal electrode E15 to terminal electrode E16, current flows in the direction indicated by arrow I21 in section C1 and in the direction indicated by arrow I22 in section C2. That is, currents flow in opposite directions in sections C1 and C2. Thus, the detection magnetic fields applied to the magnetoresistive bars S1 and S2 in opposite directions can be canceled by the compensation coil C.

[0046] Thus, although the magnetic sensor 2 of this embodiment has two magnetoresistive strips S1 and S2, they do not employ a folded-back structure, but are connected in such a way that current flows in the same direction to each other. Therefore, the relationship between the direction of magnetic bias and the direction of current flow remains constant throughout the entire range of the magnetoresistive strips S1 and S2. As a result, irregular noise is significantly reduced, thus enabling the detection of extremely weak magnetic fields.

[0047] <Third Implementation Method>

[0048] Figure 7 This is a schematic top view illustrating the structure of the magnetic sensor 3 according to the third embodiment of the present invention.

[0049] like Figure 7 As shown, the magnetic sensor 3 of the third embodiment differs from the magnetic sensor 2 of the second embodiment in that it further forms a magnetic gap G3 extending in the y-direction between ferromagnetic films M11 and M12, and a magnetic gap G4 extending in the y-direction between ferromagnetic films M11 and M13. A magnetoresistive strip S3 is disposed at a position overlapping with the magnetic gap G3, and a magnetoresistive strip S4 is disposed at a position overlapping with the magnetic gap G4. Both magnetoresistive strips S3 and S4 are composed of multiple magnetoresistive elements R arranged in the y-direction, separated by multiple hard magnetic bodies H. The direction D of the magnetic bias applied by the hard magnetic bodies H is the same as that of the magnetoresistive strips S1 to S4.

[0050] Therefore, the detection magnetic field, which is introduced into the ferromagnetic film M11 via the external magnetic body 26, is distributed to the ferromagnetic films M12 and M13 via magnetic gaps G1 to G4. Furthermore, the detection magnetic field from the ferromagnetic film M11 towards the ferromagnetic film M12 is applied to the magnetoresistive strips S1 and S3 in the -x direction, and the detection magnetic field from the ferromagnetic film M11 towards the ferromagnetic film M13 is applied to the magnetoresistive strips S2 and S4 in the +x direction. In other words, the detection magnetic fields applied to the magnetoresistive strips S1 and S3 and S2 and S4 are opposite to each other.

[0051] like Figure 8As shown, one end of the magnetoresistive strip S1 in the y-direction is connected to terminal electrode E11, and the other end is connected to terminal electrode E12. Furthermore, one end of the magnetoresistive strip S2 in the y-direction is connected to terminal electrode E13, and the other end is connected to terminal electrode E11. Further, one end of the magnetoresistive strip S3 in the y-direction is connected to terminal electrode E13, and the other end is connected to terminal electrode E14. Moreover, one end of the magnetoresistive strip S4 in the y-direction is connected to terminal electrode E12, and the other end is connected to terminal electrode E14. Thus, magnetoresistive strips S1 to S4 constitute a full-bridge circuit. In this embodiment, terminal electrodes E11 to E14 are not connected to magnetoresistive strips S1 to S4 via other magnetoresistive elements to which the detection magnetic field is applied. Therefore, as long as current flows from terminal electrode E11 to terminal electrode E14, current flows in magnetoresistive strips S1 to S4 in the directions indicated by arrows I11 to I14, respectively. That is, current flows in magnetoresistive strips S1 to S4 in the same direction as each other. Furthermore, since the detection magnetic fields are applied to the magnetoresistive strips S1 and S3 in opposite directions to those to the magnetoresistive strips S2 and S4, the orientation and intensity of the detection magnetic field can be determined by monitoring the voltage between the terminal electrodes E12 and E13 through a detection circuit (not shown).

[0052] Furthermore, such as Figure 8 As shown, one end of the compensation coil C is connected to terminal electrode E15, and the other end of the compensation coil C is connected to terminal electrode E16. The compensation coil C is provided to impart a canceling magnetic field to the magnetoresistive bars S1 to S4, thereby enabling so-called closed-loop control. The compensation coil C includes a section C1 extending along the y-direction of magnetoresistive bar S1, a section C2 extending along the y-direction of magnetoresistive bar S2, a section C3 extending along the y-direction of magnetoresistive bar S3, and a section C4 extending along the y-direction of magnetoresistive bar S4. Moreover, when current flows from terminal electrode E15 to terminal electrode E16, current flows in the directions indicated by arrows I21 to I24 in sections C1 to C4, respectively. That is, current flows in opposite directions in sections C1 and C3 and in sections C2 and C4. Thus, the detection magnetic fields applied to magnetoresistive bars S1, S3 and magnetoresistive bars S2 and S4 in opposite directions can be canceled by the compensation coil C.

[0053] Thus, although the magnetic sensor 3 of this embodiment has four magnetoresistive bars S1 to S4, they do not employ a folded-back structure, but are connected in such a way that current flows in the same direction to each other. Therefore, the relationship between the direction of magnetic bias and the direction of current flow remains constant throughout the entire range of magnetoresistive bars S1 to S4. As a result, irregular noise is significantly reduced, thus enabling the detection of extremely weak magnetic fields.

[0054] The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention. These modifications are of course also included within the scope of the present invention.

[0055] Explanation of symbols

[0056] 1-3 magnetic sensors

[0057] 11 Sensor substrate

[0058] 12 insulating film

[0059] 13 Protective Film

[0060] 14 Low-resistivity film

[0061] 21 Sensor substrate

[0062] 22-25 insulating film

[0063] 26, 27 External magnetic bodies

[0064] C compensation coil

[0065] C1~C4 interval

[0066] Direction of magnetic bias D

[0067] E1, E2, E11~E16 terminal electrodes

[0068] G, G1~G4 magnetic gap

[0069] H hard magnetic material

[0070] Hard magnetic bodies at the ends of H1 and H2

[0071] M1, M2, M11~M13 ferromagnetic films

[0072] R magnetoresistive element

[0073] S, S1~S4 magnetic resistance strips

Claims

1. A magnetic sensor, characterized in that, have: The first magnetoresistive strip is composed of a plurality of magnetoresistive elements arranged in a first direction with a plurality of hard magnetic bodies that impart magnetic bias therebetween; First and second ferromagnetic films are arranged in a second direction orthogonal to the first direction, separated by a first magnetic gap extending along the first direction; as well as First and second terminal electrodes, The first magnetoresistive strip is positioned near the first magnetic gap and is subjected to a detection magnetic field along the second direction. One end of the first magnetoresistive strip in the first direction is connected to the first terminal electrode without passing through other magnetoresistive elements to which the detection magnetic field is applied. The other end of the first magnetoresistive strip in the first direction is connected to the second terminal electrode without passing through other magnetoresistive elements to which the detection magnetic field is applied. Viewed from a third direction orthogonal to the first and second directions, the first and second ferromagnetic films overlap with the plurality of magnetoresistive elements and the plurality of hard magnetic bodies.

2. The magnetic sensor according to claim 1, characterized in that, It also has: A first end hard magnetic body is disposed at one end of the first magnetic reluctance strip; and A second hard magnetic body is disposed at the other end of the first magnetic reluctance strip. The first and second ferromagnetic films do not overlap with the first and second end hard magnetic bodies.

3. The magnetic sensor according to claim 1, characterized in that, The first magnetoresistive strip includes a low-resistance film that interconnects the plurality of magnetoresistive elements and has a resistance value lower than that of the magnetoresistive elements and the hard magnetic body. A portion of the low-resistivity film is disposed between the magnetoresistive element and the hard magnetic body.

4. The magnetic sensor according to any one of claims 1 to 3, characterized in that, It also has: The second magnetoresistive strip is composed of a plurality of magnetoresistive elements arranged in the first direction with a plurality of hard magnetic bodies that impart magnetic bias therebetween. The third ferromagnetic film; and Third terminal electrode, The first and third ferromagnetic films are arranged in the second direction separated by a second magnetic gap extending along the first direction. The second magnetoresistive strip is positioned near the second magnetic gap, and the detection magnetic field is applied along the second direction. One end of the second magnetoresistive strip in the first direction is connected to the third terminal electrode without passing through other magnetoresistive elements to which the detection magnetic field is applied. The other end of the second magnetoresistive strip in the first direction is connected to the first terminal electrode without passing through other magnetoresistive elements to which the detection magnetic field is applied. The directions of the current flowing through the first and second magnetoresistive strips are the same. The magnetic biases applied to the first and second magnetoresistive strips are in the same direction.

5. The magnetic sensor according to claim 4, characterized in that, It also includes: a compensation coil that imparts a canceling magnetic field to the first and second magnetoresistive strips. The compensation coil includes a first section extending along the first magnetic reluctance strip in the first direction, and a second section extending along the second magnetic reluctance strip in the first direction. The currents flowing in the first interval and the second interval flow in opposite directions.

6. The magnetic sensor according to claim 4, characterized in that, It also has: The third and fourth magnetoresistive strips are composed of a plurality of magnetoresistive elements arranged in the first direction with a plurality of hard magnetic bodies imparting magnetic bias; and Fourth terminal electrode, The first and second ferromagnetic films also form a third magnetic gap extending along the first direction. The first and third ferromagnetic films also form a fourth magnetic gap extending along the first direction. The third magnetoresistive strip is positioned near the third magnetic gap, and the detection magnetic field is applied along the second direction. The fourth magnetoresistive strip is positioned near the fourth magnetic gap, and the detection magnetic field is applied along the second direction. One end of the third magnetoresistive strip in the first direction is connected to the third terminal electrode without passing through other magnetoresistive elements to which the detection magnetic field is applied. The other end of the third magnetoresistive strip in the first direction is connected to the fourth terminal electrode without passing through other magnetoresistive elements to which the detection magnetic field is applied. One end of the fourth magnetoresistive strip in the first direction is connected to the second terminal electrode without passing through other magnetoresistive elements to which the detection magnetic field is applied. The other end of the fourth magnetoresistive strip in the first direction is connected to the fourth terminal electrode without passing through other magnetoresistive elements to which the detection magnetic field is applied. The currents flowing in the first to fourth magnetoresistive strips are in the same direction. The magnetic biases applied to the first to fourth magnetoresistive strips are in the same direction.

7. The magnetic sensor according to claim 6, characterized in that, It also includes: a compensation coil, which imparts a canceling magnetic field to the first to fourth magnetoresistive strips. The compensation coil includes a first section extending along the first magnetic reluctance strip in the first direction, a second section extending along the second magnetic reluctance strip in the first direction, a third section extending along the third magnetic reluctance strip in the first direction, and a fourth section extending along the fourth magnetic reluctance strip in the first direction. The directions of the current flowing in the first interval and the third interval are the same. The directions of the current flowing in the second interval and the fourth interval are the same. The currents flowing in the first interval and the second interval flow in opposite directions.

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