A Z-axis magnetic sensor

Abstract

The utility model relates to a Z-axis magnetic sensor, comprising: a substrate, a magnetic flux permeable device, and at least four magnetoresistive units R1, R2, R3, and R4 with the same sensitivity coefficient; the four magnetoresistive units are arranged on the substrate and connected to form a Wheatstone full bridge, the magnetoresistive units R1 and R2 constitute a first half bridge, the magnetoresistive units R3 and R4 constitute a second half bridge, the two half bridges are respectively located outside the two opposite side surfaces of the magnetic flux permeable device, the two magnetoresistive units on the upper bridge arm of the Wheatstone full bridge have the same sensitive direction, and the two magnetoresistive units on the two lower bridge arms have the same sensitive direction. The utility model arranges two half-bridge circuits on the opposite sides of the magnetic flux permeable device, and at the same time ensures that the magnetoresistive units on the upper bridge arm of the Wheatstone full bridge have the same sensitive direction, and the magnetoresistive units on the two bridge arms of the lower bridge arm of the Wheatstone full bridge have the same sensitive direction, so that the interference signal of the horizontal interference field in the differential signal output by the two half-bridge circuits can be eliminated.

Description

Technical Field

[0001] The utility model relates to the technical field of design and preparation of magnetic electronic devices, in particular to a Z-axis magnetic sensor. Background Art

[0002] Magnetic sensors can sense changes in physical quantities related to magnetic phenomena and convert them into electrical signals for detection, thereby directly or indirectly detecting physical information such as magnetic field size, direction, displacement, angle, current, etc. Magnetic sensors are widely used in fields such as electromechanical automatic control, biological detection and aerospace industry to measure physical parameters such as current, position, direction, etc. by sensing magnetic field strength.

[0003] In the prior art, there are many different types of sensors used to measure magnetic fields and other parameters, such as magnetic sensors using Hall elements, anisotropic magnetoresistance (AMR) elements or giant magnetoresistance (GMR) elements as sensitive elements. Although Hall magnetic sensors can work in high-intensity magnetic fields, they have disadvantages such as low sensitivity, high power consumption, and poor linearity. Although AMR magnetic sensors are more sensitive than Hall sensors, their manufacturing process is complex, power consumption is high, and they are not suitable for high-intensity magnetic fields. GMR magnetic sensors have higher sensitivity than Hall magnetic sensors, but their linear range is low and they are also not suitable for high-intensity magnetic fields. Tunneling magnetoresistance (TMR) elements are new magnetoresistance effect sensors that have begun to be used industrially in recent years. They use the tunneling magnetoresistance effect of magnetic multilayer film materials to sense magnetic fields. They have higher sensitivity, lower power consumption, better linearity and a wider working range than the AMR elements and GMR elements that have been discovered and applied before.

[0004] However, the current mainstream Z-axis magnetic sensors do not have the function of resisting external field interference and are easily affected by interfering magnetic fields, resulting in reduced current measurement accuracy. In order to eliminate external field interference, magnetic sensors generally need to electroplate NiFe materials on the top and bottom of the existing structure to shield horizontal magnetic field interference. However, this technical means currently leads to a complex structure; and there is a situation where the influence of interfering external fields cannot be completely offset, which will cause output errors in the Z-axis magnetic sensor.

[0005] Therefore, a Z-axis magnetic sensor is needed that can better reduce horizontal magnetic field interference. Utility Model Content

[0006] The utility model aims to provide a Z-axis magnetic sensor to solve the technical problems in the prior art that the Z-axis magnetic sensor has complex process and results and cannot completely offset external field interference.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] The utility model provides a Z-axis magnetic sensor, comprising:

[0009] A substrate, a magnetic flux permeator and at least four magnetoresistive units R1, R2, R3, R4 with the same sensitivity coefficient;

[0010] The magnetic flux conductor is arranged on the substrate and is used to convert the Z-axis magnetic field into the magnetic field in the X-axis direction;

[0011] The magnetoresistance units R1, R2, R3, and R4 are arranged on the substrate and connected to form a Wheatstone full bridge. The magnetoresistance units R1 and R2 constituting the first half bridge of the Wheatstone full bridge are located outside the first side surface of the magnetic flux permeator, and the magnetoresistance units R3 and R4 constituting the second half bridge of the Wheatstone full bridge are located outside the second side surface of the magnetic flux permeator. The first side surface and the second side surface are opposite. The first side surface or the second side surface is a ZY plane, and the sensitive directions of the magnetoresistance units R1, R2, R3, and R4 are parallel to the normal line of ZY.

[0012] The two magnetoresistance units R1 and R3 on the upper bridge arm of the Wheatstone full bridge have the same sensitive direction, and the two magnetoresistance units R2 and R4 on the two lower bridge arms have the same sensitive direction.

[0013] According to the present invention, preferably, the magnetoresistance units R1, R2, R3, and R4 have equal resistance values ​​under zero magnetic field.

[0014] According to the utility model, preferably, the magnetic flux conductor can be made of a soft magnetic material with high magnetic permeability including NiFe.

[0015] According to the utility model, preferably, at the locations of the two magnetoresistive units R1 and R2, the conversion rate of the magnetic flux permeator to the Z-axis magnetic field is At the location of the magnetoresistive units R3 and R4, the conversion rate of the magnetic flux permeator to the Z-axis magnetic field is ; Conversion rate ,in, The Z-axis magnetic field at the location of resistor Rn The transformed magnetic field intensity in the X-axis direction, where n is a positive integer.

[0016] According to the utility model, preferably, at the locations of the two magnetoresistive units R1 and R3, the conversion rate of the magnetic flux permeator to the Z-axis magnetic field is At the location of the magnetoresistive units R2 and R4, the conversion rate of the magnetic flux permeator to the Z-axis magnetic field is ; Conversion rate ,in, The Z-axis magnetic field at the location of the magnetoresistive unit Rn The transformed magnetic field intensity in the X-axis direction, where n is a positive integer.

[0017] According to the utility model, preferably, the conversion rate , Equal or unequal.

[0018] According to the utility model, preferably, the conversion rate , Equal or unequal.

[0019] According to the utility model, preferably, a shielding layer for the XY direction magnetic field surrounding the magnetic flux conductor and the magnetoresistive units R1, R2, R3, R4 is provided on the substrate.

[0020] According to the present invention, preferably, the magnetoresistive units R1, R2, R3, R4 are XMR type magnetoresistive units, and the XMR includes TMR, GMR and AMR.

[0021] The beneficial effects of the utility model are as follows: the utility model arranges two half-bridge circuits on opposite sides of the magnetic flux conductor respectively, while ensuring that the sensitive directions of the magnetoresistance units on the upper bridge arm of the Wheatstone full bridge are the same, and the sensitive directions of the magnetoresistance units on the two bridge arms on the lower bridge arm of the Wheatstone full bridge are the same, so that the interference signal of the horizontal interference field in the differential signal output by the two half-bridge circuits can be eliminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the structure of the Z-axis magnetic sensor for reducing external field interference according to the first embodiment of the utility model;

[0024] Figure 2 This is a schematic diagram of the Wheatstone full-bridge structure of a magnetic sensor according to a first embodiment of the present utility model;

[0025] Figure 3 It is a structural schematic diagram of a Z-axis magnetic sensor for reducing external field interference according to a second implementation manner provided by an embodiment of the utility model;

[0026] Figure 4 It is a schematic diagram of the Wheatstone full-bridge structure of the magnetic sensor of the second implementation mode provided in the embodiment of the utility model. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] In this application, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0030] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0031] The utility model provides a Z-axis magnetic sensor for reducing external field interference. A plurality of embodiments are given below to describe in detail the Z-axis magnetic sensor for reducing external field interference provided by the utility model.

[0032] Example 1

[0033] The utility model provides a Z-axis magnetic sensor, see Figure 1 and Figure 2 , specifically including:

[0034] A substrate, a flux magnetizer and four magnetoresistance units R1, R2, R3 and R4 arranged on the substrate, the magnetoresistance units R1 and R2 constitute two bridge arms of a first half-bridge circuit, the magnetoresistance units R3 and R4 constitute two bridge arms of a second half-bridge circuit, and the first half-bridge circuit and the second half-bridge circuit are connected to form a Wheatstone full bridge. The flux magnetizer is arranged on the substrate and is used to convert the Z-axis magnetic field into a magnetic field in the X-axis direction. The magnetoresistance units R1 and R2 constituting the first half-bridge circuit are located outside the first side surface of the flux magnetizer, and the magnetoresistance units R3 and R4 constituting the second half-bridge circuit are located outside the second side surface of the flux magnetizer, wherein the first side surface and the second side surface are opposite; if the first side surface or the second side surface is a ZY plane, the sensitive directions of the magnetoresistance units R1, R2, R3 and R4 are parallel to the normal line of ZY.

[0035] Specifically, the sensitivity coefficients of the four magnetoresistance units are the same, and the static resistances under zero magnetic field are equal. The two magnetoresistance units R1 and R3 on the upper bridge arm constituting the Wheatstone full bridge have the same sensitive direction, the two magnetoresistance units R2 and R4 on the lower bridge arm constituting the Wheatstone full bridge have the same sensitive direction, and the magnetoresistance units R1 and R2 constituting the first half-bridge circuit have opposite sensitive directions.

[0036] Specifically, the magnetic flux conductor is a strip-shaped NiFe soft magnetic material.

[0037] Specifically, the magnetoresistive unit may be an XMR type magnetoresistive unit, including TMR, GMR and AMR. In this embodiment, the magnetoresistive unit is a TMR unit.

[0038] Specifically, at the locations of the magnetoresistive units R1 and R2, the conversion rates of the magnetic flux permeator to the Z-axis magnetic field are both At the location of the magnetoresistive units R3 and R4, the conversion rate of the magnetic flux permeator to the Z-axis magnetic field is ; Conversion rate ,in, The Z-axis magnetic field at the location of resistor Rn The converted magnetic field strength in the X-axis direction; that is, the converted magnetic fields at the positions of the magnetoresistance units R1 and R2 are exactly the same, that is, the distances between the magnetoresistance units R1 and R2 and the strip NiFe soft magnetic material are the same; similarly, the converted magnetic fields at the positions of the magnetoresistance units R3 and R4 are exactly the same, that is, the distances between the magnetoresistance units R3 and R4 and the strip NiFe soft magnetic material are the same; wherein , Can be equal or unequal, in this embodiment , They are not equal, that is, the conversion magnetic fields at the locations of the magnetoresistance units R1 and R3 are different, and the distances between the magnetoresistance units R1 and R3 and the strip-shaped NiFe soft magnetic material are different.

[0039] The above magnetoresistive units are all regarded as standard linear magnetic sensors, and the horizontal right direction is defined as positive. Assuming that the component of the external interference magnetic field in the vertical current plane and in the sensitive direction of the magnetoresistive unit is ΔH, the magnetic field magnitude of the magnetoresistive units R1 and R2 is H1, and the magnetic field magnitude of the magnetoresistive units R3 and R4 is H2, then the resistance values ​​of the magnetoresistive units R1, R2, R3, and R4 are:

[0040] R1=R0+K(-H1+ΔH)(1)

[0041] R2=R0-K(-H1+ΔH)(2)

[0042] R3=R0+K(H2+ΔH)(3)

[0043] R4=R0-K(H2+ΔH)(4)

[0044] Therefore, according to formula (1) and formula (2), the voltage value of the output V1 of the first half-bridge circuit is:

[0045] V1=R2 / (R1+R2)=0.5+ K(H1-ΔH) / 2R0 (5)

[0046] According to formula (3) and formula (4), the voltage value of the output V2 of the second half-bridge circuit is:

[0047] V2=R4 / (R3+R4)=0.5- K(H2+ΔH) / 2R0 (6)

[0048] Therefore, according to formula (5) and formula (6), the output V of the Wheatstone full-bridge circuit is obtained out The voltage value is:

[0049] V out =V1-V2=K / 2R0*(H1+H2)(7)

[0050] Furthermore, since the distances between the magnetoresistive units R1 and R3 and the strip-shaped NiFe soft magnetic material are different, the conversion efficiencies of the magnetic fields H1 and H2 are different. For the Z-axis field Hz:

[0051] H1= Hz (8)

[0052] H2= Hz (9)

[0053] Therefore, the voltage value of the output Vout of the full-bridge circuit is:

[0054] Vout=K( + ) / 2R0*Hz(10)

[0055] According to formulas (7) and (10), it can be seen that the output Vout of the full-bridge circuit is independent of the external interference magnetic field component ΔH, thereby completely eliminating the influence of the external interference magnetic field on the output voltage.

[0056] Furthermore, a shielding layer for the XY direction magnetic field surrounding the magnetic flux conductor and the magnetoresistive units R1, R2, R3, and R4 may be provided on the substrate to shield the horizontal interference field.

[0057] Example 2

[0058] The utility model provides a Z-axis magnetic sensor, see Figure 3 and Figure 4 , specifically including:

[0059] A substrate, a flux magnetizer and four magnetoresistance units R5, R6, R7 and R8 arranged on the substrate, the magnetoresistance units R5 and R6 constitute two bridge arms of a first half-bridge circuit, the magnetoresistance units R7 and R8 constitute two bridge arms of a second half-bridge circuit, and the first half-bridge circuit and the second half-bridge circuit are connected to form a Wheatstone full bridge. The flux magnetizer is arranged on the substrate and is used to convert the Z-axis magnetic field into a magnetic field in the X-axis direction. The magnetoresistance units R5 and R6 constituting the first half-bridge circuit are located outside the first side surface of the flux magnetizer, and the magnetoresistance units R7 and R8 constituting the second half-bridge circuit are located outside the second side surface of the flux magnetizer, wherein the first side surface and the second side surface are opposite; if the first side surface or the second side surface is a ZY plane, the sensitive direction of the magnetoresistance units R5, R6, R7 and R8 is parallel to the normal line of ZY.

[0060] Specifically, the sensitivity coefficients of the four magnetoresistive units are the same, and the two magnetoresistive units R5 and R7 on the upper bridge arm constituting the Wheatstone full bridge have the same sensitive direction, the two magnetoresistive units R6 and R8 on the lower bridge arm constituting the Wheatstone full bridge have the same sensitive direction, and the magnetoresistive units R5 and R6 constituting the first half-bridge circuit have the same sensitive direction.

[0061] Specifically, the magnetic flux conductor is a strip-shaped NiFe soft magnetic material.

[0062] Specifically, the magnetoresistive unit may be an XMR type magnetoresistive unit, including TMR, GMR and AMR. In this embodiment, the magnetoresistive unit is a TMR unit.

[0063] Specifically, at the locations of the magnetoresistive units R5 and R7, the conversion rates of the magnetic flux permeator to the Z-axis magnetic field are both ; At the location of the magnetoresistive units R6 and R8, the conversion rate of the magnetic flux permeator to the Z-axis magnetic field is ; Conversion rate ,in, The Z-axis magnetic field at the location of resistor Rn The converted magnetic field strength in the X-axis direction; that is, the converted magnetic fields at the positions of the magnetoresistance units R5 and R7 are exactly the same, that is, the distances between the magnetoresistance units R5 and R7 and the strip NiFe soft magnetic material are the same; similarly, the converted magnetic fields at the positions of the magnetoresistance units R6 and R8 are exactly the same, that is, the distances between the magnetoresistance units R6 and R8 and the strip NiFe soft magnetic material are the same; wherein , Can be equal or unequal, in this embodiment , They are not equal, that is, the conversion magnetic fields at the locations of the magnetoresistance units R5 and R6 are different, and the distances between the magnetoresistance units R5 and R6 and the strip-shaped NiFe soft magnetic material are different.

[0064] The above magnetoresistive units are all regarded as standard linear magnetic sensors, and the horizontal right direction is defined as positive. Assuming that the component of the external interference magnetic field in the vertical current plane and in the sensitive direction of the magnetoresistive unit is ΔH, the magnetic field magnitude of the magnetoresistive units R5 and R7 is H3, and the magnetic field magnitude of the magnetoresistive units R6 and R8 is H4, then the resistance values ​​of the magnetoresistive units R5, R6, R7, and R8 are:

[0065] R5=R0+K(-H3+ΔH)(11)

[0066] R6=R0+K(-H4+ΔH)(12)

[0067] R7=R0+K(H3+ΔH)(13)

[0068] R8=R0+K(H4+ΔH)(14)

[0069] Therefore, according to formula (11) and formula (12), the voltage value of the output V1 of the first half-bridge circuit is:

[0070] V1=R6 / (R5+R6)=(R0+K(-H4+ΔH) / ( 2R0+K(-H3-H4+2ΔH))(15)

[0071] According to formula (13) and formula (14), the voltage value of the output V2 of the second half-bridge circuit is:

[0072] V2=R8 / (R7+R8)=(R0+K(H4+ΔH) / ( 2R0+K(H3+H4+2ΔH))(16)

[0073] Therefore, assuming that the R0 value is large, the output V of the full-bridge circuit is obtained according to formula (9), formula (15) and formula (16): out The voltage value is:

[0074] V out =V2-V1=K / R0*H4=K / R0* *Hz (17)

[0075] According to formula (17), the output Vout of the full-bridge circuit has nothing to do with the external interference magnetic field component ΔH, thereby completely eliminating the influence of the external interference magnetic field on the output voltage.

[0076] Furthermore, a shielding layer for the XY direction magnetic field surrounding the magnetic flux conductor and the magnetoresistive units R5, R6, R7, and R8 may be provided on the substrate to shield the horizontal interference field.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. A Z-axis magnetic sensor, characterized in that: The Z-axis magnetic sensor comprises: a substrate, a magnetic flux permeator and at least four magnetoresistive units R1, R2, R3, and R4 with the same sensitivity coefficient; The magnetic flux conductor is arranged on the substrate and is used to convert the Z-axis magnetic field into the magnetic field in the X-axis direction; The magnetoresistance units R1, R2, R3, and R4 are arranged on the substrate and connected to form a Wheatstone full bridge. The magnetoresistance units R1 and R2 constituting the first half bridge of the Wheatstone full bridge are located outside the first side surface of the magnetic flux permeator, and the magnetoresistance units R3 and R4 constituting the second half bridge of the Wheatstone full bridge are located outside the second side surface of the magnetic flux permeator. The first side surface and the second side surface are opposite. The first side surface or the second side surface is a ZY plane, and the sensitive directions of the magnetoresistance units R1, R2, R3, and R4 are parallel to the normal line of ZY. The two magnetoresistance units R1 and R3 on the upper bridge arm of the Wheatstone full bridge have the same sensitive direction, and the two magnetoresistance units R2 and R4 on the two lower bridge arms have the same sensitive direction.

2. The Z-axis magnetic sensor according to claim 1, wherein: The magnetoresistive units R1 , R2 , R3 , and R4 have equal resistance values ​​under zero magnetic field.

3. The Z-axis magnetic sensor according to claim 1, wherein: The magnetic flux conductor is made of a soft magnetic material with high magnetic permeability including NiFe.

4. The Z-axis magnetic sensor according to claim 3, characterized in that: At the locations of the two magnetoresistive units R1 and R2, the conversion rate of the magnetic flux permeator to the Z-axis magnetic field is ; At the location of the magnetoresistive units R3 and R4, the conversion rate of the magnetic flux permeator to the Z-axis magnetic field is ; Conversion rate ,in, The Z-axis magnetic field at the location of resistor Rn The transformed magnetic field intensity in the X-axis direction, where n is a positive integer.

5. The Z-axis magnetic sensor according to claim 3, characterized in that: At the locations of the two magnetoresistive units R1 and R3, the conversion rate of the magnetic flux permeator to the Z-axis magnetic field is At the location of the magnetoresistive units R2 and R4, the conversion rate of the magnetic flux permeator to the Z-axis magnetic field is ; Conversion rate ,in, The Z-axis magnetic field at the location of the magnetoresistive unit Rn The transformed magnetic field intensity in the X-axis direction, where n is a positive integer.

6. The Z-axis magnetic sensor according to claim 4, characterized in that: The conversion rate , Equal or unequal.

7. The Z-axis magnetic sensor according to claim 5, characterized in that: The conversion rate , Equal or unequal.

8. The Z-axis magnetic sensor according to any one of claims 1 to 7, characterized in that: A shielding layer for the XY direction magnetic field surrounding the magnetic flux conductor and the magnetoresistive units R1 , R2 , R3 , and R4 is disposed on the substrate.

9. The Z-axis magnetic sensor according to claim 8, characterized in that: The magnetoresistive units R1 , R2 , R3 , and R4 are XMR type magnetoresistive units, and the XMR includes TMR, GMR, and AMR.

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