magnetic sensor

Abstract

The present application provides a magnetic sensor with improved generation efficiency of canceling magnetic field. The magnetic sensor (1) of the present application comprises: magnetic body layers (M1, M2) opposite through a magnetic gap (G2), a magnetic sensitive element (R) arranged on a magnetic circuit formed by the magnetic gap (G2), and a compensation coil (120) wound on the magnetic body layers (M1, M2), the magnetic body layers (M1, M2), the magnetic sensitive element (R) and the compensation coil (120) are integrated in a sensor chip (100). In this way, since the compensation coil (120) is wound on the magnetic body layers (M1, M2), the generation efficiency of canceling magnetic field is improved. Therefore, the amount of current flowing through the compensation coil (120) is reduced, so that not only the power consumption can be reduced, but also the thermal noise of the magnetic sensitive element (R) can be reduced.

Description

Technical Field

[0001] This invention relates to magnetic sensors, and more particularly to magnetic sensors comprising a compensation coil that cancels out the magnetic field of the object being detected. Background Technology

[0002] Patent Document 1 discloses a magnetic sensor that includes a compensation coil to counteract the magnetic field of the detected object. In the magnetic sensor described in Patent Document 1, the compensation coil is arranged at a position overlapping the magnetic sensing element, such that the compensation coil surrounds the magnetic sensing element.

[0003] Existing technical documents

[0004] Patent documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-179738 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, the compensation coil described in Patent Document 1 has low efficiency in generating the canceling magnetic field. Therefore, in order to generate a sufficient canceling magnetic field, a large current needs to flow through the compensation coil. As a result, there are problems such as increased power consumption and increased thermal noise of the magnetic sensitive element due to the heating of the compensation coil.

[0008] Therefore, the object of the present invention is to provide a magnetic sensor that improves the generation efficiency of a canceling magnetic field.

[0009] Methods for solving problems

[0010] The magnetic sensor of the present invention is characterized in that it comprises: first and second magnetic body layers opposite each other with a magnetic gap; a magnetic sensitive element disposed on a magnetic circuit formed by the magnetic gap; and a compensation coil wound on the first and second magnetic body layers, wherein the first magnetic body layer, the second magnetic body layer, the magnetic sensitive element and the compensation coil are integrated into a sensor chip.

[0011] According to the present invention, since the compensation coil integrated into the sensor chip is wound on a magnetic layer, the efficiency of generating the canceling magnetic field is improved. Consequently, the amount of current required to flow through the compensation coil is reduced, thus reducing not only power consumption but also thermal noise of the magnetic sensing element.

[0012] In this invention, the sensor chip may also have a first layer, a second layer, a third layer, and a fourth layer stacked sequentially. The compensation coil includes a plurality of lower layer patterns formed on the first layer and a plurality of upper layer patterns formed on the fourth layer. The magnetic sensing element is formed on the second layer, and the first magnetic body layer and the second magnetic body layer are formed on the third layer. This improves the efficiency of generating the canceling magnetic field and enables the application of the detection magnetic field to the magnetic sensing element efficiently.

[0013] In this invention, two adjacent through-hole conductors among the plurality of through-hole conductors connecting the lower and upper patterns, which are orthogonal to the extension direction of the magnetic gap, may be positioned differently in the extension direction of the magnetic gap. This increases the distance between adjacent through-hole conductors, thus simplifying design and manufacturing.

[0014] In this invention, any pattern from multiple lower-layer patterns and multiple upper-layer patterns may overlap with the magnetic sensing element when viewed from above. This allows for the efficient application of a canceling magnetic field to the magnetic sensing element.

[0015] In this invention, the first and second magnetic layers may also have: a first edge forming one end in a first direction orthogonal to the extension direction of the magnetic gap and located on the magnetic gap side, and a second edge forming the other end in the first direction and located on the opposite side of the first edge; the edge of the compensation coil in the first direction is located at a position equal to or closer to the magnetic gap side than the second edge. This improves the efficiency of generating the canceling magnetic field.

[0016] Alternatively, the magnetic sensor of the present invention may further include: a first external magnetic body covering the first magnetic body layer, and a second external magnetic body covering the second magnetic body layer. This results in a higher magnetic focusing effect.

[0017] Invention Effects

[0018] As described above, according to the present invention, a magnetic sensor that improves the generation efficiency of a canceling magnetic field can be provided. Attached Figure Description

[0019] Figure 1 This is a general perspective view showing the appearance of a magnetic sensor 1 according to one embodiment of the present invention.

[0020] Figure 2 This is a rough exploded 3D view of magnetic sensor 1.

[0021] Figure 3 This is a schematic top view used to illustrate the structure of the element forming surface 101 of the sensor chip 100.

[0022] Figure 4 It is along Figure 3 The approximate cross-sectional view of line AA is shown.

[0023] Figure 5 It is along Figure 3 The diagram shows a rough cross-section of the BB line.

[0024] Figure 6 It is a schematic top view used to illustrate the positional relationship between the magnetic layers M1 and M2 and the magnetic sensitive element R.

[0025] Figure 7 This is a general three-dimensional view showing the state after the magnetic layers M1 and M2 and the compensation coil 120 have been removed from the sensor chip 100.

[0026] Figure 8 This is an XZ cross-sectional view of the main part of sensor chip 100.

[0027] Figure 9 This is a circuit diagram showing the circuit used to obtain the detection signal V1.

[0028] Figure 10 This is a schematic top view used to illustrate the location of the dummy element D1.

[0029] Figure 11 This is a circuit diagram showing the circuit used to obtain detection signals V2 and V3.

[0030] Figure 12 It is a schematic top view used to illustrate the positions of the dummy elements D1 to D3.

[0031] Figure 13 This is a schematic top view used to illustrate the structure of the element forming surface 101 in the modified example.

[0032] Figure 14 This is a schematic top view illustrating the structure of the magnetic layers M1 and M2 in the modified example.

[0033] Figure 15 This is a schematic top view used to illustrate the structure of the element forming surface 101 in the modified example.

[0034] Figure 16 This is a graph showing the relationship between the positional relationship of the magnetic sensitive element R and the lower pattern 121 in the X direction and the efficiency of generating the counteracting magnetic field.

[0035] Figure 17 (a) to (c) are schematic diagrams illustrating the positional relationship between the magnetic sensitive element R and the lower pattern 121 in the X direction.

[0036] Figure 18 It is a graph showing the positional relationship between the edges of magnetic layers M1 and M2 in the X direction and the edge of compensation coil 120 in the X direction, and the relationship between the generation efficiency of the counteracting magnetic field.

[0037] Figure 19 (a) and (b) are schematic diagrams illustrating the positional relationship in the X direction between the edge of the magnetic layer M2 and the edge of the upper pattern 122.

[0038] Explanation of reference numerals in the attached figures

[0039] 1. Magnetic sensor

[0040] 8 substrate

[0041] 10, 20 External magnetic bodies

[0042] 11.21 Main body

[0043] 12, 22 protrusions

[0044] 100 sensor chips

[0045] 101 Component Forming Surface

[0046] 102 Back

[0047] 103 mounting surface

[0048] 104 Upper surface

[0049] Side views of 105 and 106

[0050] 110 Chip Body

[0051] Insulation layers 111, 112, 113, and 114

[0052] 120 Compensation Coil

[0053] 121 Lower layer pattern

[0054] 122 Upper layer pattern

[0055] 123 Through-hole conductor

[0056] 124 and 125 are connected to solder pads.

[0057] 131-134 terminal electrodes

[0058] D1~D3 dummy components

[0059] G1~G3 magnetic gap

[0060] L1, L2 wiring

[0061] M1~M3 Magnetic Layers

[0062] R, R1, R2 magnetic sensitive elements

[0063] Fixed resistors R10 to R13

[0064] V1~V3 detection signals Detailed Implementation

[0065] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0066] Figure 1This is a general perspective view showing the appearance of a magnetic sensor 1 according to one embodiment of the present invention. Figure 2 This is a rough exploded 3D view of magnetic sensor 1.

[0067] like Figure 1 and Figure 2 As shown, the magnetic sensor 1 of this embodiment includes: a substrate 8, a sensor chip 100 mounted on the substrate 8, and external magnetic bodies 10 and 20. The substrate 8 has an XZ plane as its main surface, on which the sensor chip 100 and external magnetic bodies 10 and 20 are mounted. The sensor chip 100 has: an element forming surface 101 and a back surface 102 that form the XY plane and are located opposite each other; a mounting surface 103 and a top surface 104 that form the XZ plane and are located opposite each other; and side surfaces 105 and 106 that form the YZ plane and are located opposite each other. The sensor chip 100 is vertically mounted on the substrate 8 with the mounting surface 103 facing the main surface of the substrate 8.

[0068] Both external magnetic bodies 10 and 20 are made of high-permeability materials such as ferrite. External magnetic body 10 consists of a rod-shaped main body 11 with the X-direction as its long side and a protrusion 12 located at the X-direction end of the main body 11. Similarly, external magnetic body 20 consists of a rod-shaped main body 21 with the X-direction as its long side and a protrusion 22 located at the X-direction end of the main body 21. The main body 11 and the protrusion 12 can be integral or composed of separate blocks. The same applies to the main body 21 and the protrusion 22.

[0069] The thickness of the protrusions 12 and 22 in the Z direction is thinner than the thickness of the main body portions 11 and 21 in the Z direction. Furthermore, as... Figure 1 As shown, the sensor chip 100 and the external magnetic body 10 are positioned on the substrate 8 such that a portion of the element forming surface 101 of the sensor chip 100 is covered by the protrusion 12 of the external magnetic body 10, and the side surface 105 of the sensor chip 100 is covered by the X-direction end face of the main body 11 of the external magnetic body 10. Similarly, the sensor chip 100 and the external magnetic body 20 are positioned on the substrate 8 such that another portion of the element forming surface 101 of the sensor chip 100 is covered by the protrusion 22 of the external magnetic body 20, and the side surface 106 of the sensor chip 100 is covered by the X-direction end face of the main body 21 of the external magnetic body 20. Thus, a magnetic gap G1 is formed between the protrusion 12 and the protrusion 22.

[0070] Figure 3 This is a schematic top view illustrating the structure of the element forming surface 101 of the sensor chip 100. Additionally, Figure 4 It is along Figure 3 The diagram shows a rough cross-section of line AA. Figure 5 It is along Figure 3 The diagram shows a rough cross-section of the BB line.

[0071] like Figures 3-5 As shown, magnetic layers M1 and M2, a magnetic sensing element R, and a compensation coil 120 wound around the magnetic layers M1 and M2 are disposed on the element forming surface 101 of the sensor chip 100. The magnetic sensing element R is not particularly limited as long as it is an element whose resistance changes according to the direction of magnetic flux; for example, an MR element can be used. The sensitivity axis of the magnetic sensing element R, i.e., the fixed magnetization direction, is the X-direction. The magnetic layers M1 and M2 are thin films made of NiFe-based materials such as permalloy. Figure 6 As shown, magnetic layers M1 and M2 are arranged along the X direction, separated by a magnetic gap G2 extending along the Y direction. In the top view viewed from the Z direction, a magnetic sensitive element R is positioned at the location overlapping with the magnetic gap G2. The width of the magnetic gap G2 in the X direction is narrower than that of the magnetic gap G1. Magnetic layer M1 is covered by the protrusion 12 of the external magnetic body 10, and magnetic layer M2 is covered by the protrusion 22 of the external magnetic body 20. Thus, the magnetic field collected by the external magnetic bodies 10 and 20 in the X direction passes through the magnetic gap G2 along the X direction and is applied to the magnetic sensitive element R through the magnetic gap G2.

[0072] The sensor chip 100 includes a chip body 110 constituting an element forming surface 101, and insulating layers 111, 112, 113, and 114 sequentially stacked on the surface of the chip body 110. Multiple lower layer patterns 121 constituting a compensation coil 120 are provided on the surface of the insulating layer 111 constituting the first layer. A magnetic sensing element R is provided on the surface of the insulating layer 112 constituting the second layer. Magnetic layers M1 and M2 are provided on the surface of the insulating layer 113 constituting the third layer. Multiple upper layer patterns 122 constituting the compensation coil 120 are provided on the surface of the insulating layer 114 constituting the fourth layer. The ends of the lower layer patterns 121 in the Y direction and the ends of the upper layer patterns 122 in the Y direction are connected by multiple through-hole conductors 123 penetrating the insulating layers 112 to 114.

[0073] The lower pattern 121 and the upper pattern 122 are conductor patterns extending along the Y direction, overlapping with the magnetic layers M1 and M2, but not overlapping with the magnetic layers M1 and M2 at their ends in the Y direction. The ends of the lower pattern 121 and the upper pattern 122 in the Y direction form an enlarged connection pad in the X direction, on which a through-hole conductor 123 is formed. The lower pattern 121 is located below the magnetic layers M1 and M2, i.e., on the -Z direction side, and the upper pattern 122 is located above the magnetic layers M1 and M2, i.e., on the +Z direction side. Furthermore, by connecting these lower and upper patterns 121 and 122 via the through-hole conductor 123, a compensation coil 120 consisting of a continuous coil pattern is formed. Figure 3 In this configuration, connection pad 124 is one end of the compensation coil 120, and connection pad 125 is the other end. According to this structure, since magnetic layers M1 and M2 are arranged in the inner diameter region of the compensation coil 120, when current flows through the compensation coil 120, the resulting canceling magnetic field is applied to the magnetic sensitive element R via the magnetic layers M1 and M2. The compensation coil 120 is used for so-called closed-loop control by canceling the magnetic field applied to the magnetic sensitive element R. Furthermore, since the magnetic layers M1 and M2 have high permeability, a larger magnetic flux can be applied to the magnetic sensitive element R with a smaller current.

[0074] Figure 7 This is a general three-dimensional view showing the state after the magnetic layers M1 and M2 and the compensation coil 120 have been removed from the sensor chip 100.

[0075] like Figure 7 As shown, the magnetic sensitive element R extends along the Y direction on the element forming surface 101, with one end connected to the terminal electrode 131 via wiring L1 and the other end connected to the terminal electrode 132 via wiring L2. The terminal electrodes 133 and 134 are connected to the connection pads 124 and 125 of the compensation coil 120, respectively.

[0076] Figure 8 This is an XZ cross-sectional view of the main part of sensor chip 100.

[0077] like Figure 8 As shown, when viewed from above in the Z direction, the magnetic sensing element R is located between magnetic layers M1 and M2. Therefore, a magnetic field is applied to the magnetic sensing element R through the magnetic gap G2. That is, the magnetic sensing element R is positioned near the magnetic gap G2 formed by magnetic layers M1 and M2, and is able to detect the magnetic field of the target object passing through the magnetic gap G2. Thus, it is not necessary to position the magnetic sensing element R between the two magnetic layers M1 and M2; any arrangement where at least a portion of the magnetic field through the magnetic gap G2 formed by magnetic layers M1 and M2 is applied to the magnetic sensing element R is acceptable. There is no particular limitation on the relationship between the width of the magnetic gap G2 and the width of the magnetic sensing element R. Figure 8 In the example shown, the width G2x of the magnetic gap G2 in the X direction is narrower than the width Rx of the magnetic sensing element R in the X direction. Therefore, when viewed from the Z direction, the magnetic layers M1 and M2 overlap with the magnetic sensing element R by 0V. To apply more magnetic field through the magnetic gap G2 to the magnetic sensing element R, preferably, the distance between the overlapping magnetic layers M1 and M2 and the magnetic sensing element R in the Z direction is as close as possible; more preferably, the distance between the magnetic layers M1 and M2 and the magnetic sensing element R in the Z direction is closer than the width G2x of the magnetic gap G2 in the X direction. Thus, the magnetic sensing element R becomes the main magnetic path for the magnetic field passing through the magnetic gap G2.

[0078] like Figure 9 As shown, if the magnetic sensing element R and the fixed resistor R10 are connected in series between the power supply, a detection signal V1 can be obtained from the connection point. Furthermore, if a compensation current based on the detection signal V1 flows through the compensation coil 120, closed-loop control can be performed. The fixed resistor R10 can be located within the sensor chip 100 itself or on the substrate 8. When the fixed resistor R10 is located within the sensor chip 100 itself, as... Figure 10 As shown, a dummy element D1 with the same structure as the magnetic sensing element R can also be placed at a position that completely overlaps with the magnetic layer M1 or the magnetic layer M2, and this dummy element D1 can be used as a fixed resistor R10. Although the dummy element D1 has the same structure as the magnetic sensing element R, because it completely overlaps with the magnetic layer M1 or the magnetic layer M2, almost no magnetic field is applied in the magnetic sensing direction, i.e., the X direction, and thus it can be used as a fixed resistor.

[0079] Or, it can be like Figure 11 As shown, the configuration is such that detection signals V2 and V3 are obtained by bridging the magnetic sensing element R with fixed resistors R11 to R13. In this case, as... Figure 12 As shown, dummy elements D1 to D3, which have the same structure as the magnetic sensitive element R, can also be placed at a position that completely overlaps with the magnetic body layer M1 or the magnetic body layer M2, and these dummy elements D1 to D3 can be used as fixed resistors R11 to R13.

[0080] As explained above, in the magnetic sensor 1 of this embodiment, since a compensation coil 120 is wound around the magnetic layers M1 and M2, the efficiency of generating the canceling magnetic field by the compensation coil 120 can be improved. Therefore, the amount of current flowing through the compensation coil 120 is reduced, thus reducing both power consumption and thermal noise of the magnetic sensing element R. Furthermore, since the magnetic layers M1 and M2, the magnetic sensing element R, and the compensation coil 120 are all integrated into the sensor chip 100, the number of components is not increased.

[0081] In addition, such as Figure 3 As shown, multiple through-hole conductors 123 are arranged in an alternating pattern. Thus, two adjacent through-hole conductors in the X direction are positioned differently in the Y direction. Therefore, the distance between adjacent through-hole conductors 123 can be ensured, and the number of turns of the compensation coil 120 can be increased. However, in this invention, it is not necessary to arrange the multiple through-hole conductors 123 in an alternating pattern. The arrangement can be determined according to the required number of turns of the compensation coil 120 and the design rules of the through-hole conductors 123, such as... Figure 13 As shown in the modified example, multiple through-hole conductors 123 can also be arranged in a row along the X direction.

[0082] Furthermore, the planar shapes of the magnetic layers M1 and M2 are not particularly limited, and can be as follows: Figure 14 As shown in the modified example, it has a narrowing shape portion whose width in the Y direction narrows as it approaches the magnetic gap G2. Additionally, as... Figure 15 As shown in the modified example, three magnetic layers M1, M2, and M3 can also be provided, with a magnetic sensitive element R1 placed near the magnetic gap G2 formed by the magnetic layers M1 and M2, and a magnetic sensitive element R2 placed near the magnetic gap G3 formed by the magnetic layers M2 and M3.

[0083] Figure 16 This is a graph showing the relationship between the positional relationship of the magnetic sensitive element R and the lower pattern 121 in the X direction and the efficiency of generating the counteracting magnetic field. Figure 16 The horizontal axis represents the difference between the center position of the magnetic sensing element R in the X direction and the center position of the lower pattern 121 closest to the magnetic sensing element R in the X direction. For example, when the width of the magnetic sensing element R in the X direction is 5 μm and the width of the lower pattern 121 in the X direction is 30 μm, such as... Figure 17 As shown in (a), when the centers of the two are at the same position, the difference is 0 μm. Additionally, as... Figure 17 As shown in (b), when the center position of the magnetic sensing element R coincides with the edge position of the lower pattern 121, the difference is 15 μm. Furthermore, as Figure 17 As shown in (c), when the magnetic sensing element R does not overlap with the lower pattern 121 and their edge positions are consistent, the difference becomes 17.5 μm. Figure 16 As shown, the closer the magnetic sensing element R is to the lower pattern 121 in the X-direction, the higher the efficiency of generating the canceling magnetic field. The efficiency is highest when their centers are aligned. Similarly, the overlap between the magnetic sensing element R and the upper pattern 122 is also important. That is, any pattern in the lower or upper pattern 122 overlaps with the magnetic sensing element R when viewed from above, and their centers are close in the X-direction, thereby improving the efficiency of generating the canceling magnetic field.

[0084] Figure 18 It is a graph showing the positional relationship between the edges of the magnetic layers M1 and M2 in the X direction and the edge of the compensation coil 120 in the X direction, and the relationship between the generation efficiency of the counteracting magnetic field. Figure 18 The horizontal axis represents the difference between the edge of the magnetic layers M1 and M2 in the X direction and the edge of the compensation coil 120 in the X direction. Here, the edge of the magnetic layers M1 and M2 in the X direction refers to the edge opposite to the edge located on the magnetic gap G2 side. For example, as... Figure 19 As shown in (a), when the edge of the magnetic layer M2 is aligned with the edge of the upper pattern 122 in the X direction, its value is 0 μm. Additionally, as... Figure 19As shown in (b), when the edge of the magnetic layer M2 protrudes further in the X direction than the edge of the upper pattern 122, that is, when the edge of the upper pattern 122 in the X direction is located closer to the magnetic gap G2 than the edge of the magnetic layer M2, its value is positive. Figure 18 As shown, the larger the value of the horizontal axis, the higher the efficiency of counteracting the magnetic field.

[0085] The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. Various modifications can be made without departing from the spirit of the present invention, and these modifications are of course included within the scope of the present invention.

Claims

1. A magnetic sensor, characterized in that, include: The first and second magnetic layers are separated by a magnetic gap; A magnetically sensitive element disposed on a magnetic circuit formed by the magnetic gap; and The compensation coil wound around the first and second magnetic layers, The first magnetic layer, the second magnetic layer, the magnetic sensing element, and the compensation coil are integrated into the sensor chip. The sensor chip has: a chip body, and a first layer, a second layer, a third layer, and a fourth layer sequentially stacked on the chip body. The compensation coil includes: a plurality of lower layer patterns formed on the first layer, and a plurality of upper layer patterns formed on the fourth layer. The magnetic sensitive element is formed in the second layer. The first and second magnetic layers are formed on the third layer.

2. The magnetic sensor according to claim 1, characterized in that, Two of the through-hole conductors among the plurality of through-hole conductors connecting the lower pattern and the upper pattern, which are adjacent in a direction orthogonal to the extension direction of the magnetic gap, are positioned differently in the extension direction of the magnetic gap.

3. The magnetic sensor according to claim 1, characterized in that, Any one of the plurality of lower layer patterns and the plurality of upper layer patterns overlaps with the magnetic sensitive element when viewed from above.

4. The magnetic sensor according to claim 1, characterized in that, The first and second magnetic layers have: a first edge forming one end in a first direction orthogonal to the extension direction of the magnetic gap and located on the magnetic gap side; and a second edge forming the other end in the first direction and located on the opposite side of the first edge. The edge of the compensation coil in the first direction is located at a position equal to or closer to the magnetic gap side than the second edge.

5. The magnetic sensor according to any one of claims 1 to 4, characterized in that, Also includes: The first outer magnetic body covering the first magnetic body layer; and A second outer magnetic body covering the second magnetic body layer.

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