Magnetic sensor

Abstract

To provide a magnetic sensor capable of detecting magnetic fields in the low-frequency range with high sensitivity. [Solution] The magnetic sensor 10 includes a sensor chip 100 which includes a magnetosensitive element MR1 disposed near a magnetic gap G1 formed by magnetic layers 131 and 132, and a magnetosensitive element MR2 disposed near a magnetic gap G2 formed by magnetic layers 131 and 133; an external magnetic body 51 which is arranged so that a portion of the magnetic field to be detected flows from magnetic layer 131 to magnetic layer 132 through the magnetic gap G1, and another portion of the magnetic field to be detected flows from magnetic layer 131 to magnetic layer 133 through the magnetic gap G2; and a compensation coil C1 which cancels the magnetic field to be detected. The sensor chip further includes a modulation coil C2 which is wound so that a modulated magnetic field flows from magnetic layer 132 to magnetic layer 131 through the magnetic gap G1, and further flows from magnetic layer 131 to magnetic layer 133 through the magnetic gap G2.

Description

Technical Field

[0001] The present disclosure relates to a magnetic sensor, and more particularly to a magnetic sensor capable of highly sensitive detection of a magnetic field in a low-frequency region.

Background Art

[0002] Currently, magnetic sensors using magnetosensitive elements are used in various fields. However, in order to detect an extremely weak magnetic field, a magnetic sensor with a high signal-to-noise ratio is required. Here, 1 / f noise is cited as a factor that reduces the signal-to-noise ratio of the magnetic sensor. Since 1 / f noise becomes more prominent as the frequency component of the magnetic field to be measured is lower, for example, in order to highly sensitively detect a magnetic field in a low-frequency region such as 1 kHz or less, it is important to reduce 1 / f noise.

[0003] As a magnetic sensor with reduced 1 / f noise, the magnetic sensor described in Patent Document 1 is known. The magnetic sensor described in Patent Document 1 reduces 1 / f noise by mechanically displacing the magnetic path at a predetermined frequency.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, there is a problem that when the magnetic path is mechanically displaced, magnetic noise is generated due to the displacement of the magnetic path.

[0006] In the present disclosure, an improved magnetic sensor capable of highly sensitive detection of a magnetic field in a low-frequency region is described.

Means for Solving the Problems

[0007] A magnetic sensor according to one aspect of the present disclosure includes a sensor chip comprising a substrate, first, second, and third magnetic layers provided on the substrate, a first magnetic sensor element disposed near a first magnetic gap formed by the first and second magnetic layers, and a second magnetic sensor element disposed near a second magnetic gap formed by the first and third magnetic layers; a first external magnetic material disposed such that a portion of the magnetic field to be detected flows from the first magnetic layer through the first magnetic gap to the second magnetic layer, and another portion of the magnetic field to be detected flows from the first magnetic layer through the second magnetic gap to the third magnetic layer; and a compensation coil for canceling the magnetic field to be detected, wherein the sensor chip further includes a modulation coil wound such that a modulated magnetic field flows from the second magnetic layer through the first magnetic gap to the first magnetic layer, and further flows from the first magnetic layer through the second magnetic gap to the third magnetic layer. [Effects of the Invention]

[0008] This disclosure provides an improved magnetic sensor capable of detecting magnetic fields in the low-frequency range with high sensitivity. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic perspective view showing the external appearance of a magnetic sensor 10 according to a first embodiment of the present disclosure. [Figure 2] Figure 2 is a schematic plan view of the sensor chip 100. [Figure 3] Figure 3 is a schematic cross-sectional view along line AA shown in Figure 2. [Figure 4] Figure 4 is a schematic plan view showing the sensor chip 100 with the magnetic layers 131-133 removed. [Figure 5] Figure 5(a) shows the direction of the detection target magnetic field applied to the magnetic sensing elements MR1 ​​to MR4, and Figure 5(b) shows the direction of the modulated magnetic field applied to the magnetic sensing elements MR1 ​​to MR4. [Figure 6] Figure 6 is a schematic plan view of the sensor chip 100A according to the first modified example. [Figure 7]Figure 7 is a schematic cross-sectional view along the line BB shown in Figure 6. [Figure 8] Figure 8 is a schematic plan view of the sensor chip 100B according to the second modified example. [Figure 9] Figure 9 is a schematic perspective view showing the external appearance of the magnetic sensor 20 according to a second embodiment of the present disclosure. [Figure 10] Figure 10 is a schematic plan view of the sensor chip 100C according to the third modified example. [Figure 11] Figure 11 is a schematic perspective view showing the external appearance of a magnetic sensor 30 according to a third embodiment of the present disclosure. [Modes for carrying out the invention]

[0010] The embodiments of the technology described herein will be described in detail below with reference to the attached drawings.

[0011] Figure 1 is a schematic perspective view showing the external appearance of a magnetic sensor 10 according to a first embodiment of the present disclosure.

[0012] As shown in Figure 1, the magnetic sensor 10 according to this embodiment comprises a circuit board 40 made of an insulating material, a sensor chip 100 mounted on a mounting surface 41 constituting the XZ plane of the circuit board 40, and an external magnetic body 51. The external magnetic body 51 is a rod-shaped body with its longitudinal direction in the Z direction for concentrating magnetic flux on the sensor chip 100, and is made of a high-permeability material such as ferrite.

[0013] Figure 2 is a schematic plan view of the sensor chip 100. Figure 3 is a schematic cross-sectional view along line AA shown in Figure 2.

[0014] As shown in FIGS. 2 and 3, the sensor chip 100 has a substrate 110 and insulating films 121 to 125 laminated on the main surface 111 of the substrate 110. The surfaces of the insulating films 121 to 124 respectively constitute wiring layers L1 to L4. Magnet layers 131 to 133 made of permalloy or the like are formed on the wiring layer L3. The magnet layer 131 is disposed substantially at the center in the X direction on the main surface 111 of the substrate 110. As shown in FIG. 1, the end of the external magnet 51 is disposed at a position overlapping the magnet layer 131 in a plan view seen from the Z direction. The magnet layers 132 and 133 are disposed on both sides in the X direction on the main surface 111 of the substrate 110 so as to sandwich the magnet layer 131 in the X direction.

[0015] The magnet layer 131 and the magnet layer 132 form two magnetic gaps G1 and G3 that extend in the Y direction with the X direction as the width direction. The positions of the magnetic gap G1 and the magnetic gap G3 in the X direction coincide with each other, and both are arranged in the Y direction. The magnet layer 131 and the magnet layer 133 form two magnetic gaps G2 and G4 that extend in the Y direction with the X direction as the width direction. The positions of the magnetic gap G2 and the magnetic gap G4 in the X direction coincide with each other, and both are arranged in the Y direction. Further, the magnetic gap G1 and the magnetic gap G2 are arranged in the X direction, and the magnetic gap G3 and the magnetic gap G4 are arranged in the X direction.

[0016] Magnetosensitive elements MR1 to MR4 are disposed in the vicinity of the magnetic gaps G1 to G4, respectively. The magnetosensitive elements MR1 to MR4 are not particularly limited as long as they are elements whose electrical resistance changes depending on the direction of the magnetic flux, and for example, MR elements or the like can be used. The fixed magnetization directions of the magnetosensitive elements MR1 to MR4 are aligned in the same direction (for example, the positive side in the X direction) with each other. The magnetosensitive elements MR1 to MR4 are disposed on the wiring layer L2 so as to overlap the magnetic gaps G1 to G4 in a plan view seen from the Z direction. Thereby, the detection target magnetic field in the X direction passing through the magnetic gaps G1 to G4 is applied to the magnetosensitive elements MR1 to R4, respectively.

[0017] With such a configuration, the detection target magnetic field in the Z direction collected by the external magnetic body 51 is divided into a component in the -X direction and a component in the +X direction after being applied to the magnetic body layer 131. The component in the -X direction flows through the magnetic body layer 132 via the magnetic gaps G1 and G3, and the component in the +X direction flows through the magnetic body layer 133 via the magnetic gaps G2 and G4. As a result, a part of the detection target magnetic field collected by the external magnetic body 51 is applied to the magnetosensitive elements MR1 and MR3 in the -X direction, while another part of the detection target magnetic field collected by the external magnetic body 51 is applied to the magnetosensitive elements MR2 and MR4 in the +X direction.

[0018] FIG. 4 is a schematic plan view showing a state in which the magnetic body layers 131 to 133 are removed from the sensor chip 100.

[0019] As shown in FIG. 4, terminal electrodes 161 to 168 are provided on the sensor chip 100. The terminal electrode 161 is a terminal to which the power supply potential V DD is supplied, and is connected to one ends of the magnetosensitive elements MR1 and MR2 via the wiring 170. The terminal electrode 162 is a terminal to which the ground potential GND is supplied, and is connected to one ends of the magnetosensitive elements MR3 and MR4 via the wirings 175 and 176, respectively. The other ends of the magnetosensitive elements MR1 and MR4 are commonly connected to the terminal electrode 164 via the wirings 171 and 174, respectively. The other ends of the magnetosensitive elements MR2 and MR3 are commonly connected to the terminal electrode 163 via the wirings 172 and 173, respectively.

[0020] Thereby, the magnetosensitive elements MR1 to MR4 form a full-bridge circuit shown in FIG. 5(a), an output voltage Va is output from the terminal electrode 163, and an output voltage Vb is output from the terminal electrode 164. And since the detection target magnetic field collected by the external magnetic body 51 is applied to the magnetosensitive elements MR1 and MR3 in the -X direction, while being applied to the magnetosensitive elements MR2 and MR4 in the +X direction, the output signal, which is the difference (Va - Vb) between the output voltage Va and the output voltage Vb, indicates the direction and intensity of the detection target magnetic field collected by the external magnetic body 51.

[0021] Furthermore, a compensation coil C1 is provided in the wiring layer L1. The compensation coil C1 includes sections 141 and 142 that extend in the Y direction. Section 141 is located in a position that overlaps with the magnetic sensing elements MR1 ​​and MR3, and section 142 is located in a position that overlaps with the magnetic sensing elements MR2 and MR4. One end of the compensation coil C1 is connected to terminal electrode 165, and the other end of the compensation coil C1 is connected to terminal electrode 166. As a result, when a current corresponding to the difference between the output voltage Va and the output voltage Vb (Va-Vb) is passed through the compensation coil C1 via terminal electrodes 165 and 166, currents flow in opposite directions through sections 141 and 142. Consequently, the target magnetic field applied to the magnetic sensing elements MR1 ​​to MR4 is canceled out, making it possible to measure the target magnetic field using so-called closed-loop control.

[0022] Furthermore, modulation coils C2 are provided in the wiring layers L1 and L4. The modulation coil C2 includes a section 151 that is positioned in the wiring layer L1 so as to overlap with the magnetic layer 132 and extends in the Y direction, and a section 152 that is positioned in the wiring layer L4 so as to overlap with the magnetic layer 133 and extends in the Y direction. Sections 151 and 152 are connected via a section 153 that extends in the X direction.

[0023] One end of the modulation coil C2 is connected to terminal electrode 167, and the other end of the modulation coil C2 is connected to terminal electrode 168. As a result, when an excitation current is passed through the modulation coil C2 via terminal electrodes 167 and 168, a unidirectional modulating magnetic field flows through the magnetic layers 131 and 133. For example, when an excitation current is passed from terminal electrode 167 to terminal electrode 168, a modulating magnetic field in the +X direction is generated in both magnetic layers 131 and 133. In other words, the modulating magnetic field flows from magnetic layer 132 through magnetic gaps G1 and G3 to magnetic layer 131, and then from magnetic layer 131 through magnetic gaps G2 and G4 to magnetic layer 133.

[0024] As a result, as shown in Figure 5(b), the modulated magnetic field is applied to the magnetic sensing elements MR1 ​​to MR4 in the same direction. Therefore, even when a modulated magnetic field is applied, the output voltages Va and Vb do not change, and the difference between the output voltages Va and Vb (Va-Vb) also does not change. In other words, the modulated magnetic field is not canceled by the compensation coil C1. The amount of excitation current is set to a current sufficient to saturate the magnetic material layers 131 to 133 due to the modulated magnetic field. As a result, the magnetic material layers 131 to 133 are saturated during the period when the excitation current is flowing, so even when a target magnetic field is applied, the difference between the output voltages Va and Vb (Va-Vb), which are the output signals, becomes zero. If the magnetic material layers 131 to 133 are saturated due to the modulated magnetic field, it is acceptable for the magnetic sensing elements MR1 ​​to MR4 to be in a saturated state as well.

[0025] With this configuration, when an excitation current with a frequency sufficiently higher than the frequency of the magnetic field to be detected is passed through the modulation coil C2, the output signal is modulated by the frequency of the excitation current. As a result, 1 / f noise is reduced even when the frequency component of the magnetic field to be detected is low.

[0026] As described above, the sensor chip 100 included in the magnetic sensor 10 of this embodiment is equipped with a modulation coil C2 that applies a modulated magnetic field in the same direction to the magnetosensitive elements MR1 ​​to MR4 via the magnetic layers 131 to 133. Therefore, a modulated magnetic field that is not canceled by the compensation coil C1 can be applied to the magnetosensitive elements MR1 ​​to MR4. Furthermore, since the magnetic sensor 10 of this embodiment does not involve mechanical displacement of the magnetic path, no magnetic noise due to displacement of the magnetic path is generated.

[0027] Furthermore, since the modulation coil C2 is integrated into the sensor chip 100, it is possible to efficiently apply the modulated magnetic field to the magnetosensitive elements MR1 ​​to MR4. In addition, since a portion of the modulation coil C2 (for example, section 151) is placed on the same wiring layer as the compensation coil C1, the increase in the number of wiring layers is kept to a minimum.

[0028] Figure 6 is a schematic plan view of the sensor chip 100A according to the first modified example. Figure 7 is a schematic cross-sectional view along the line BB shown in Figure 6.

[0029] As shown in Figures 6 and 7, the sensor chip 100A according to the first modification differs from the sensor chip 100 shown in Figures 2 and 3 in that the modulation coil C2 consists of sections 181 to 185. Since the other basic configurations are the same as those of the sensor chip 100 shown in Figures 2 and 3, the same reference numerals are used for the same elements, and redundant explanations are omitted.

[0030] Section 181 of the modulation coil C2 consists of multiple wirings arranged in the wiring layer L1 so as to overlap with the magnetic material layer 132. Section 182 of the modulation coil C2 consists of multiple wirings arranged in the wiring layer L4 so as to overlap with the magnetic material layer 132. Section 183 of the modulation coil C2 consists of multiple wirings arranged in the wiring layer L1 so as to overlap with the magnetic material layer 133. Section 184 of the modulation coil C2 consists of multiple wirings arranged in the wiring layer L4 so as to overlap with the magnetic material layer 132.

[0031] One end of section 181 is connected to one end of section 182 via a via conductor that penetrates the insulating films 122-124, and the other end of section 181 is connected to the other end of section 182 via a via conductor that penetrates the insulating films 122-124. As a result, sections 181 and 182 of the modulation coil C2 constitute a coil wound around the magnetic layer 132. Similarly, one end of section 183 is connected to one end of section 184 via a via conductor that penetrates the insulating films 122-124, and the other end of section 183 is connected to the other end of section 184 via a via conductor that penetrates the insulating films 122-124. As a result, sections 183 and 184 of the modulation coil C2 constitute a coil wound around the magnetic layer 133. The end of section 181 or section 182 is connected to the end of section 183 or section 184 via section 185.

[0032] With this configuration, when an excitation current is passed through the modulation coil C2 via terminal electrodes 167 and 168, a unidirectional modulation magnetic field flows through the magnetic layers 131 to 133. Furthermore, in the first modified example, since the modulation coil C2 is wound around the magnetic layers 132 and 133 over multiple turns, it becomes possible to apply a larger modulation magnetic field to the magnetosensitive elements MR1 ​​to MR4.

[0033] Figure 8 is a schematic plan view of the sensor chip 100B according to the second modified example.

[0034] As shown in Figure 8, the sensor chip 100B according to the second modification differs from the sensor chip 100A shown in Figures 6 and 7 in that the modulation coil C2 consists of sections 191 to 199, the magnetic layer 132 has aperture sections 132a and 132b, and the magnetic layer 133 has aperture sections 133a and 133b. The other basic configurations are the same as those of the sensor chip 100A shown in Figures 6 and 7, so the same reference numerals are used for the same elements, and redundant explanations are omitted.

[0035] The magnetic layer 132 has an edge 132c located on the magnetic gap G1 side, an edge 132d located on the magnetic gap G3 side, and an edge 132e located on the opposite side of edges 132c and 132d. All edges 132c to 132e extend in the Y direction. The diaphragm portion 132a of the magnetic layer 132 is located between edges 132c and 132e and is a region whose width in the Y direction is narrower than that of edge 132c, and the diaphragm portion 132b of the magnetic layer 132 is located between edges 132d and 132e and is a region whose width in the Y direction is narrower than that of edge 132d.

[0036] The magnetic layer 133 has an edge 133c located on the magnetic gap G2 side, an edge 133d located on the magnetic gap G4 side, and an edge 133e located on the opposite side of edges 133c and 133d. All edges 133c to 133e extend in the Y direction. The diaphragm portion 133a of the magnetic layer 133 is located between edges 133c and 133e and is a region whose width in the Y direction is narrower than that of edge 133c, and the diaphragm portion 133b of the magnetic layer 133 is located between edges 133d and 133e and is a region whose width in the Y direction is narrower than that of edge 133d.

[0037] Sections 191 and 192 of the modulation coil C2 consist of multiple wires arranged on wiring layers L1 and L4 respectively so as to overlap with the constricted portion 132b of the magnetic layer 132, thereby winding sections 191 and 192 of the modulation coil C2 around the constricted portion 132b of the magnetic layer 132. Sections 193 and 194 of the modulation coil C2 consist of multiple wires arranged on wiring layers L1 and L4 respectively so as to overlap with the constricted portion 132a of the magnetic layer 132, thereby winding sections 193 and 194 of the modulation coil C2 around the constricted portion 132a of the magnetic layer 132. Sections 195 and 196 of the modulation coil C2 consist of multiple wires arranged on wiring layers L1 and L4 respectively so as to overlap with the constricted portion 133a of the magnetic layer 133, thereby winding sections 195 and 196 of the modulation coil C2 around the constricted portion 133a of the magnetic layer 133. Sections 197 and 198 of the modulation coil C2 consist of multiple wires arranged in wiring layers L1 and L4, respectively, so as to overlap with the constricted portion 133b of the magnetic layer 133, thereby winding sections 197 and 198 of the modulation coil C2 around the constricted portion 133b of the magnetic layer 133. One end of section 193 or section 194 is connected to one end of section 195 or section 196 via section 199.

[0038] In this way, by providing apertures in the magnetic layers 132 and 133 and winding the modulation coil C2 around the apertures, it becomes possible to apply a larger modulation magnetic field to the magnetosensitive elements MR1 ​​to MR4.

[0039] Figure 9 is a schematic perspective view showing the external appearance of the magnetic sensor 20 according to a second embodiment of the present disclosure.

[0040] As shown in Figure 9, the magnetic sensor 20 according to this embodiment differs from the magnetic sensor 10 according to the first embodiment in that an external magnetic material 52 is added and the sensor chip 100 is replaced with a sensor chip 100C according to a third modification. The other basic configurations are the same as those of the magnetic sensor 10 according to the first embodiment, so the same elements are denoted by the same reference numerals and redundant explanations are omitted.

[0041] The external magnetic material 52, like the external magnetic material 51, is made of a high-permeability material such as ferrite. The external magnetic material 52 includes a rod-shaped portion 521 that extends in the Z direction and covers the back surface 112 (see Figure 3) of the substrate 110 that constitutes the sensor chip 100C, protruding portions 522 and 523 that protrude from the rod-shaped portion 521 in the +Z direction, a bent portion 524 that is bent in the +X direction from the protruding portion 522 so as to overlap with the magnetic material layer 132 in a plan view from the Z direction, and a bent portion 525 that is bent in the -X direction from the protruding portion 523 so as to overlap with the magnetic material layer 133 in a plan view from the Z direction. As a result, the magnetic field in the Z direction collected by the external magnetic material 51 is divided in the X direction in the magnetic layer 131. The component bent in the -X direction flows to the magnetic layer 132 through magnetic gaps G1 and G3, and then flows to the rod-shaped portion 521 of the external magnetic material 52 via the bent portion 524 and protruding portion 522 of the external magnetic material 52. Meanwhile, the component bent in the +X direction flows to the magnetic layer 133 through magnetic gaps G2 and G4, and then flows to the rod-shaped portion 521 of the external magnetic material 52 via the bent portion 525 and protruding portion 523 of the external magnetic material 52. By adding such an external magnetic material 52, the magnetoresistance in the Z direction is reduced, making it possible to further increase the detection sensitivity.

[0042] Figure 10 is a schematic plan view of the sensor chip 100C according to the third modified example.

[0043] As shown in Figure 10, the sensor chip 100C according to the third modification differs from the sensor chip 100B shown in Figure 8 in that sections 191 to 194 of the modulation coil C2 are offset in the -X direction from the center position in the X direction of the magnetic layer 132, and sections 195 to 198 of the modulation coil C2 are offset in the +X direction from the center position in the X direction of the magnetic layer 133. In other words, the distance from sections 191 and 192 of the modulation coil C2 to the edge 132e of the magnetic layer 132 is shorter than the distance from sections 191 and 192 of the modulation coil C2 to the edge 132d of the magnetic layer 132, and the distance from sections 193 and 194 of the modulation coil C2 to the edge 132e of the magnetic layer 132 is shorter than the distance from sections 193 and 194 of the modulation coil C2 to the edge 132c of the magnetic layer 132. Similarly, the distance between sections 195 and 196 of the modulation coil C2 and the edge 133e of the magnetic layer 133 is shorter than the distance between sections 195 and 196 of the modulation coil C2 and the edge 133c of the magnetic layer 133, and the distance between sections 197 and 198 of the modulation coil C2 and the edge 133e of the magnetic layer 133 is shorter than the distance between sections 197 and 198 of the modulation coil C2 and the edge 133d of the magnetic layer 133. Sections 191 to 194 of the modulation coil C2 may overlap with the bent portion 524 of the external magnetic material 52 in a plan view from the Z direction, and sections 195 to 198 of the modulation coil C2 may overlap with the bent portion 525 of the external magnetic material 52 in a plan view from the Z direction.

[0044] As illustrated by the magnetic sensor 20 according to the second embodiment, by adding an external magnetic material 52 and offsetting the sections 191-194 and 195-198 of the modulation coil C2, the intensity of the modulation magnetic field applied to the magnetic sensing elements MR1-MR4 is suppressed, making it easier to saturate the magnetic material layers 131-133 before the magnetic sensing elements MR1-MR4 become saturated.

[0045] Figure 11 is a schematic perspective view showing the external appearance of a magnetic sensor 30 according to a third embodiment of the present disclosure.

[0046] As shown in Figure 11, the magnetic sensor 30 according to this embodiment differs from the magnetic sensor 20 according to the second embodiment in that a molded member 60 covering the external magnetic material 51 is added, and the compensation coil C1 is wound around the external magnetic material 51 via the molded member 60. The other basic configurations are the same as those of the magnetic sensor 20 according to the second embodiment, so the same elements are denoted by the same reference numerals, and redundant explanations are omitted.

[0047] The molded member 60 is made of a non-magnetic insulating material such as resin and is fixed to the external magnetic body 51 using an adhesive or the like. The molded member 60 holds U-shaped pins P1 and P2. One end of the compensation coil C1 is fixed to one end of pin P1, and the other end of the compensation coil C1 is fixed to one end of pin P2. The coil axis direction of the compensation coil C1 is in the Z direction.

[0048] As illustrated by the magnetic sensor 30 according to the third embodiment, it is not necessary to integrate the compensation coil C1 into the sensor chip; it may be wound around the external magnetic material 51. Alternatively, the compensation coil C1 may be wound around the external magnetic material 52, or it may be wound around both the external magnetic materials 51 and 52.

[0049] While embodiments of the technology described herein have been explained above, it goes without saying that the technology described herein is not limited to the embodiments described above, and various modifications are possible without departing from its spirit, and these modifications are also included within the scope of the technology described herein.

[0050] For example, in each of the embodiments described above, the sensor chip includes four magnetic elements MR1 ​​to MR4, but this is not essential in the present invention. Two magnetic elements MR1 ​​and MR2 may be connected in a half-bridge configuration, or magnetic elements MR3 and MR4 may be replaced with fixed resistors.

[0051] The technology relating to this disclosure includes, but is not limited to, the following configuration examples.

[0052] A magnetic sensor according to one aspect of the present disclosure includes a sensor chip comprising a substrate, first, second, and third magnetic layers provided on the substrate, a first magnetic sensor element disposed near a first magnetic gap formed by the first and second magnetic layers, and a second magnetic sensor element disposed near a second magnetic gap formed by the first and third magnetic layers; a first external magnetic material disposed such that a portion of the magnetic field to be detected flows from the first magnetic layer through the first magnetic gap to the second magnetic layer, and another portion of the magnetic field to be detected flows from the first magnetic layer through the second magnetic gap to the third magnetic layer; and a compensation coil for canceling the magnetic field to be detected, wherein the sensor chip further includes a modulation coil wound such that a modulated magnetic field flows from the second magnetic layer through the first magnetic gap to the first magnetic layer, and further flows from the first magnetic layer through the second magnetic gap to the third magnetic layer. According to this, since a modulated magnetic field that is not canceled by the compensation coil can be applied to the first and second magnetosensitive elements, the output signal can be modulated according to the frequency of the excitation current.

[0053] In the magnetic sensor described above, the modulation coil may include a section that overlaps with the second magnetic layer and a section that overlaps with the third magnetic layer. This makes it possible to apply a modulation magnetic field to both the second and third magnetic layers.

[0054] In the magnetic sensor described above, the sensor chip includes a first wiring layer located between the substrate and the first to third magnetic layers, and a second wiring layer located on the opposite side of the substrate from the first to third magnetic layers. The modulation coil may include a plurality of first sections arranged in the first and second wiring layers so as to overlap with the second magnetic layer, and a plurality of second sections arranged in the first and second wiring layers so as to overlap with the third magnetic layer. This makes it possible to efficiently apply a modulation magnetic field to the second and third magnetic layers.

[0055] In the magnetic sensor described above, the second magnetic layer has a first edge located on the side of the first magnetic gap and a second edge located on the opposite side of the first edge, the third magnetic layer has a third edge located on the side of the second magnetic gap and a fourth edge located on the opposite side of the third edge, the second magnetic layer has a first aperture portion that is narrower than the first and second edges, and the third magnetic layer has a second aperture portion that is narrower than the third and fourth edges, and a plurality of first sections may be wound around the first aperture portion, and a plurality of second sections may be wound around the second aperture portion. This makes it possible to apply a modulated magnetic field to the second and third magnetic layers more efficiently.

[0056] In the magnetic sensor described above, the distance between multiple first sections and the second edge may be shorter than the distance between multiple first sections and the first edge, and the distance between multiple second sections and the fourth edge may be shorter than the distance between multiple second sections and the third edge. This makes it easier to saturate the first to third magnetic layers before the first and second magnetic sensing elements become saturated.

[0057] In the magnetic sensor described above, the compensation coil may be integrated into the sensor chip. This allows for efficient application of a cancellation magnetic field to the first and second magnetic sensing elements, while also reducing the number of components.

[0058] In the magnetic sensor described above, at least a portion of the compensation coil and at least a portion of the modulation coil may be located on the same wiring layer on the substrate. This makes it possible to suppress an increase in the number of wiring layers.

[0059] In the magnetic sensor described above, the compensation coil may be wound around the first external magnetic material. This allows for easy modification of the number of turns of the compensation coil and simplifies the sensor chip.

[0060] The above magnetic sensor further comprises a second external magnetic material, wherein the first external magnetic material is arranged on the main surface side of the substrate so as to overlap with the first magnetic material layer, and the second external magnetic material may be arranged on the back side of the substrate. This makes it possible to obtain a higher magnetic collection effect. [Explanation of Symbols]

[0061] 10, 20, 30 Magnetic Sensors 40 Circuit boards 41 Implementation aspects 51,52 External magnetic material 60 Molded parts 100, 100A~100C Sensor Chip 110 circuit boards 111 Main surface 112 Back side 121-125 Insulating film 131~133 Magnetic layer 132a, 132b, 133a, 133b Aperture section 132c~132e, 133c~133e Edge Sections 141, 142, 151-153 161~168 Terminal electrode 170~176 Wiring Sections 181-185, 191-199 521 Rod-shaped body part 522,523 Protrusion 524, 525 Folded section C1 Compensation coil C2 Modulation Coil G1-G4 Magnetic Gap L1~L4 wiring layer MR1~MR4 Magnetic Sensor P1, P2 pins

Claims

1. A sensor chip comprising a substrate, first, second, and third magnetic layers provided on the substrate, a first magnetic sensor element disposed near a first magnetic gap formed by the first and second magnetic layers, and a second magnetic sensor element disposed near a second magnetic gap formed by the first and third magnetic layers, A first external magnetic material is provided, wherein a portion of the magnetic field to be detected flows from the first magnetic material layer through the first magnetic gap to the second magnetic material layer, and another portion of the magnetic field to be detected flows from the first magnetic material layer through the second magnetic gap to the third magnetic material layer, A compensation coil for canceling the magnetic field to be detected, Equipped with, The sensor chip further includes a modulation coil wound such that a modulated magnetic field flows from the second magnetic layer through the first magnetic gap to the first magnetic layer, and further flows from the first magnetic layer through the second magnetic gap to the third magnetic layer. Magnetic sensor.

2. The modulation coil includes a section that overlaps with the second magnetic layer and a section that overlaps with the third magnetic layer. The magnetic sensor according to claim 1.

3. The sensor chip includes a first wiring layer located between the substrate and the first to third magnetic layers, and a second wiring layer located on the opposite side of the substrate from the first to third magnetic layers. The modulation coil includes a plurality of first sections arranged in the first and second wiring layers so as to overlap with the second magnetic layer, and a plurality of second sections arranged in the first and second wiring layers so as to overlap with the third magnetic layer. The magnetic sensor according to claim 2.

4. The second magnetic layer has a first edge located on the side of the first magnetic gap and a second edge located on the opposite side of the first edge. The third magnetic layer has a third edge located on the side of the second magnetic gap and a fourth edge located on the opposite side of the third edge. The second magnetic layer has a first constricted portion that is narrower than the first and second edges. The third magnetic layer has a second constricted portion that is narrower than the third and fourth edges. The plurality of first sections are wound around the first diaphragm, The plurality of second sections are wound around the second throttling section. The magnetic sensor according to claim 3.

5. The distance between the plurality of first sections and the second edge is shorter than the distance between the plurality of first sections and the first edge. The distance between the plurality of second sections and the fourth edge is shorter than the distance between the plurality of second sections and the third edge. The magnetic sensor according to claim 4.

6. The compensation coil is integrated into the sensor chip. The magnetic sensor according to any one of claims 1 to 5.

7. At least a portion of the compensation coil and at least a portion of the modulation coil are located on the same wiring layer on the substrate. The magnetic sensor according to claim 6.

8. The compensation coil is wound around the first external magnetic material. The magnetic sensor according to any one of claims 1 to 5.

9. Further comprising a second external magnetic material, The first external magnetic material is arranged on the main surface side of the substrate so as to overlap with the first magnetic material layer. The second external magnetic material is arranged on the back side of the substrate. The magnetic sensor according to any one of claims 1 to 5.

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