Tunneling magnetoresistive accelerometer

Abstract

The application relates to the field of electronic sensors and provides a tunnel magnetoresistance accelerometer, which comprises a supporting structure, a mass block, a coil, an elastic beam and four tunnel magnetoresistance elements. The mass block is connected with the elastic beam and is suspended on the supporting structure. The coil is arranged on the surface of the mass block. The four tunnel magnetoresistance elements are arranged on the surface of the supporting structure and are symmetrically distributed around the mass block. The straight line where two tunnel magnetoresistance elements are located is parallel to the X direction, and the straight line where the other two tunnel magnetoresistance elements are located is parallel to the Y direction. The mass block can move under the action of acceleration in the X direction, the Y direction or the Z direction to drive the coil to move. Every two tunnel magnetoresistance elements in the four tunnel magnetoresistance elements constitute a differential magnetic field detection structure, which can sense the magnetic field change generated under the change of the movement state of the coil, and high-precision detection of single-axis, double-axis (X and Y) or three-axis (X, Y and Z) acceleration can be realized by measuring the magnetic field change value.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic sensors, in particular to a tunnel magnetoresistive accelerometer. BACKGROUND

[0002] Silicon micro-accelerometer is a typical MEMS (Micro-Electro-Mechanical System) inertial sensor, which has the characteristics of small volume, light weight, low cost, low power consumption, high reliability, easy digitization, and can meet the application in harsh environment, and is widely used. According to the sensitive signal, the silicon micro-accelerometer is classified into capacitive micro-accelerometer, piezoresistive micro-accelerometer, piezoelectric micro-accelerometer, thermal micro-accelerometer and resonant micro-accelerometer.

[0003] The capacitive micro-accelerometer is currently more widely used in industrial fields. The basic principle is to use a capacitor as a detection element. When the detection mass block is displaced by the inertial force, one of the plates of the capacitor is moved, resulting in a change in the capacitance value, thereby indirectly measuring the value of the acceleration. The capacitive micro-accelerometer has the advantages of simple structure, wide frequency range, high sensitivity, stable output, small temperature drift, low output impedance, and high practical application value. However, the readout circuit of the capacitive micro-accelerometer is complex, is easily affected by parasitic parameters, and has nonlinear characteristics.

[0004] The piezoresistive micro-accelerometer is usually composed of a cantilever beam made of silicon, a mass block at the end of the cantilever beam, and a piezoresistive film coated on the mass block. When the accelerometer is subjected to external acceleration, the mass block is subjected to the action of the inertial force, driving the cantilever beam and the piezoresistive film to deform. Due to the piezoresistive effect, the resistance value of the piezoresistive film changes, resulting in a change in the output voltage. By calculating the change, the corresponding relationship between the acceleration and the output voltage can be obtained. The piezoresistive micro-accelerometer has the advantages of simple structure, easy manufacturing, and good direct current response characteristics. The disadvantages are low sensitivity, sensitivity to temperature, and limited dynamic range.

[0005] The piezoelectric micro-accelerometer has a structure similar to that of the piezoresistive micro-accelerometer, except that the piezoresistive film is replaced by a piezoelectric film. It works based on the piezoelectric effect. The detection mass block is displaced under the excitation of acceleration, driving the piezoelectric film to deform. The piezoelectric film generates an electric charge output due to the stress, which is amplified by an amplifier and then the voltage difference can be detected. The piezoelectric micro-accelerometer has the characteristics of wide band and high sensitivity, and has a very wide dynamic range. Its working principle uses the piezoelectric effect and does not need an external power supply. Since the piezoelectric body is a charge response type, it cannot maintain the peak value of the direct current component, so it does not have static sensitivity, and temperature changes will have a certain impact on the performance of the micro-piezoelectric accelerometer.

[0006] Thermal micro-accelerometers use built-in temperature sensors and an air chamber as sensing structures, reflecting the magnitude of acceleration by detecting changes in temperature difference between one or more temperature sensors. Thermal micro-accelerometers are shock-resistant, stable, and inexpensive to manufacture due to their lack of complex mechanical structures. However, they have a slower response time, narrower bandwidth, and lower sensitivity, and are mainly used in low-end consumer electronics products.

[0007] The resonant micro-accelerometer uses a mass block at its center, connected to a base via two identical resonators. When acceleration acts on the sensor, the mass block generates inertial force, applying pressure / tension to the resonators and changing their stiffness. This change in resonator stiffness affects the resonant frequency; by detecting the frequency change of the two resonators, the magnitude of the measured signal can be obtained. The unique advantages of the resonant micro-accelerometer are its ability to directly output quasi-digital signals, strong anti-interference capabilities, and potential for operation in extreme environments. However, its manufacturing process is complex, and its energy consumption is relatively high.

[0008] Currently, most silicon micro-accelerometers employ capacitance sensing, which offers advantages such as low temperature drift, high sensitivity, high reliability, and good stability, and is widely used in single-axis, dual-axis, and triaxial accelerometer products. However, with the dramatic reduction in the structural size of silicon micro-accelerometers, the sensitivity and resolution of these instruments have significantly decreased. Furthermore, capacitance sensing is heavily influenced by parasitic effects, mechanical noise, and circuit noise, reaching its detection limit and making further substantial improvements in measurement accuracy extremely difficult. To meet the application requirements of high-precision inertial measurement systems, a new type of high-precision micro-accelerometer is urgently needed.

[0009] Tunneling magnetoresistive accelerometers are primarily based on the tunneling magnetoresistive (TMR) effect. The TMR effect refers to the phenomenon in a magnetic tunnel junction composed of two layers of ferromagnetic metal and an intermediate insulating layer. If the polarization directions of the two ferromagnetic metal layers are parallel or the tunnel gap is smaller, the probability of electrons tunneling through the insulating layer increases, and the magnetic tunnel junction macroscopically exhibits extremely low resistance. Conversely, if the polarization directions are antiparallel or the tunnel gap is larger, the probability of electrons tunneling through the insulating layer is smaller, and the magnetic tunnel junction macroscopically exhibits extremely high resistance. Therefore, by utilizing the changes in polarization direction or tunnel gap caused by input acceleration, and measuring the resulting resistance change, the magnitude of the input acceleration can be measured. Because the tunneling magnetoresistive effect is highly sensitive to the magnetization direction and gap of the magnetic field—that is, the probability of electrons tunneling through the insulating layer is highly sensitive to changes in the magnetization direction and gap—high-resolution (high-precision) acceleration detection can be achieved.

[0010] Existing tunnel magnetoresistive sensors mainly employ an assembled structure. For example, assembling two layers of coils and two tunnel magnetoresistive sensors is complex in manufacturing, making it difficult to achieve integrated manufacturing of the entire structure. Moreover, this structure can only detect single-axis acceleration and cannot detect dual-axis or tri-axis acceleration. Another approach involves assembling a detection magnet and a drive magnet, but aligning the assembled magnets is difficult, leading to detection errors, and this method cannot be integrated or mass-produced. Summary of the Invention

[0011] To address the aforementioned technical deficiencies, this invention provides a tunnel magnetoresistive accelerometer to achieve high-precision detection of uniaxial, biaxial, or triaxial acceleration.

[0012] This invention provides a tunnel magnetoresistive accelerometer, comprising: a support structure, a mass block, a coil, an elastic beam, and four tunnel magnetoresistive elements. The mass block is connected to the elastic beam, the mass block is suspended on the support structure, and the coil is disposed on the surface of the mass block.

[0013] The four tunnel magnetoresistive elements are disposed on the surface of the support structure and symmetrically distributed around the mass block. The straight lines containing two tunnel magnetoresistive elements are parallel to the X direction, and the straight lines containing the other two tunnel magnetoresistive elements are parallel to the Y direction.

[0014] The mass block can move under the action of acceleration in the X, Y or Z directions to drive the coil to move accordingly;

[0015] Two tunnel magnetoresistive elements in each of the four tunnel magnetoresistive elements constitute a differential magnetic field detection structure, which is used to sense the magnetic field changes generated by the change in the motion state of the coil.

[0016] In this embodiment of the invention, the mass block, under the action of acceleration in the X direction, drives the coil to move horizontally in the X direction. The two tunnel magnetoresistive elements parallel to the X direction sense the change in the magnitude of the magnetic field generated by the coil and output the magnetic field change value. This magnetic field change value is the difference between the magnetic field change value sensed by the two tunnel magnetoresistive elements in the X direction when the coil is in motion and the magnetic field change value when the coil is at rest.

[0017] In this embodiment of the invention, the mass block drives the coil to move horizontally along the Y direction under the action of acceleration in the Y direction. The two tunnel magnetoresistive elements parallel to the Y direction sense the change in the magnitude of the magnetic field generated by the coil and output the magnetic field change value. This magnetic field change value is the difference between the magnetic field change value of the coil in motion state sensed by the two tunnel magnetoresistive elements in the Y direction and the magnetic field change value of the coil in stationary state.

[0018] In this embodiment of the invention, the mass block drives the coil to move accordingly under the action of acceleration in the Z direction. The two tunnel magnetoresistive elements parallel to the X direction and the two tunnel magnetoresistive elements parallel to the Y direction all sense the change in the magnitude of the magnetic field generated by the coil and output the magnetic field change value. The magnetic field change value is the sum of the magnetic field change value of the coil in motion state sensed by the four tunnel magnetoresistive elements and the magnetic field change value of the coil in stationary state.

[0019] In this embodiment of the invention, the surface of the support structure has a cavity, and the mass block is located above the cavity.

[0020] In this embodiment of the invention, there are four elastic beams, the first ends of the four elastic beams are respectively fixed to the support structure, and the second ends of the four elastic beams are respectively connected to the four ends of the mass block.

[0021] In this embodiment of the invention, the mass block is centrally symmetrical in shape and has four symmetrical ends;

[0022] The second ends of the four elastic beams are respectively connected to the four symmetrical ends of the mass block;

[0023] The distance between each of the four tunnel magnetoresistive elements and the two adjacent elastic beams is equal.

[0024] In this embodiment of the invention, the planar shape of the mass block is a rectangle, a square, a circle, or a regular polygon.

[0025] In this embodiment of the invention, the coil is a planar spiral coil, and the planar shape of each turn of the planar spiral coil is a rectangle, a square, a circle, or a regular polygon.

[0026] In this embodiment of the invention, the elastic beam is a straight beam, a folded beam, a double-folded beam, a spiral beam, a crab-shaped beam, or a serpentine beam.

[0027] The tunneling magnetoresistive accelerometer proposed in this invention employs a single coil and four tunneling magnetoresistive elements. All four elements are mounted on the same support structure, and the four elements are symmetrically distributed around the mass block and the coil to form a differential magnetic field structure. The single coil serves as the excitation coil to generate the magnetic field, eliminating the need for a separate magnet. Compared to existing tunneling magnetoresistive accelerometers, this invention offers higher detection sensitivity, a simpler structure, and is easier to integrate in manufacturing. Furthermore, this invention can achieve high-precision detection of not only single-axis acceleration but also dual-axis and three-axis accelerations.

[0028] Other features and advantages of the technical solution of the present invention will be described in detail in the following detailed embodiments section. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1 This is a top view of the tunnel magnetoresistive accelerometer provided in an embodiment of the present invention;

[0031] Figure 2 This is a front view of the tunnel magnetoresistive accelerometer provided in an embodiment of the present invention (under positive acceleration in the Z direction).

[0032] Explanation of reference numerals in the attached figures

[0033] 1-Supporting structure, 2-Mass block, 3-Coil,

[0034] 4a / 4b / 4c / 4d - Elastic beams, 5a / 5b / 5c / 5d - Tunnel magnetoresistive elements. Detailed Implementation

[0035] To make the technical solutions and advantages of the embodiments of the present invention clearer, the exemplary embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0036] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0037] In this invention, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] This invention provides a tunneling magnetoresistive accelerometer, comprising: a support structure, a mass block, a coil, an elastic beam, and four tunneling magnetoresistive elements. The mass block is connected to the elastic beam and suspended on the support structure. The coil is disposed on the surface of the mass block, and the mass block and coil can move in suspension under external acceleration. The four tunneling magnetoresistive elements are disposed on the surface of the support structure and symmetrically distributed around the mass block. Two of the tunneling magnetoresistive elements are located in a line parallel to the X-direction, and the other two are located in a line parallel to the Y-direction. The mass block can move under acceleration in the X, Y, or Z directions to drive the coil. Each pair of tunneling magnetoresistive elements forms a differential magnetic field detection structure, capable of sensing changes in the magnetic field generated by changes in the coil's motion state. By measuring the magnetic field change value, high-precision detection of uniaxial (X, Y, or Z), biaxial (X and Y), or triaxial (X, Y, and Z) acceleration is achieved.

[0039] like Figure 1 and Figure 2 As shown, the tunneling magnetoresistive accelerometer provided in this embodiment of the invention includes: a support structure 1, a mass block 2, a coil 3, four elastic beams 4a / 4b / 4c / 4d, and four tunneling magnetoresistive elements 5a / 5b / 5c / 5d. The first ends of the four elastic beams 4a / 4b / 4c / 4d are respectively fixed to the support structure 1, and the second ends of the four elastic beams 4a / 4b / 4c / 4d are respectively connected to the four ends of the mass block 2. The mass block 2 is suspended above the support structure 1, and the coil 3 is disposed on the surface of the mass block 2. Due to the elastic expansion and contraction of the elastic beams, the mass block and the coil can move under the action of external acceleration. The four tunneling magnetoresistive elements 5a / 5b / 5c / 5d are disposed on the surface of the support structure 1 and symmetrically distributed around the mass block 2. The straight lines containing two tunneling magnetoresistive elements 5a / 5b are parallel to the X direction, and the straight lines containing the other two tunneling magnetoresistive elements 5c / 5d are parallel to the Y direction. The mass block moves under the action of acceleration in the X, Y or Z directions to drive the coil to move accordingly. The four tunnel magnetoresistive elements can sense the changes in the magnetic field generated by the changes in the coil's motion state.

[0040] In this embodiment, the surface of the support structure 1 has a cavity (not shown in the figure), and the mass block 2 is located above the cavity. The mass block and the coil suspended above the support structure can move horizontally under the action of external acceleration.

[0041] In this embodiment, the mass block is centrally symmetrical with four symmetrical ends. The second ends of the four elastic beams are connected to the four symmetrical ends of the mass block, respectively. Each of the four tunneling magnetoresistive elements is equidistant from its two adjacent elastic beams.

[0042] When a mass block accelerates in the X direction, it causes a coil to move horizontally along the X direction. Two tunnel magnetoresistive elements parallel to the X direction sense a change in the magnitude of the magnetic field generated by the coil and output a change in magnetic field value. This change in magnetic field value is the difference between the change in magnetic field value sensed by the two tunnel magnetoresistive elements in the X direction when the coil is moving and the change in magnetic field value sensed by the two tunnel magnetoresistive elements in the X direction when the coil is stationary. Similarly, when a mass block accelerates in the Y direction, it causes a coil to move horizontally along the Y direction. The two tunnel magnetoresistive elements parallel to the Y direction sense a change in the magnitude of the magnetic field generated by the coil and output a change in magnetic field value. This change in magnetic field value is the difference between the change in magnetic field value sensed by the two tunnel magnetoresistive elements in the Y direction when the coil is moving and the change in magnetic field value sensed by the two tunnel magnetoresistive elements in the Y direction when the coil is stationary. Based on the difference in the change in magnetic field value sensed by the tunnel magnetoresistive elements in the corresponding direction, the acceleration in that direction can be calculated, enabling accurate detection of uniaxial (X, Y, or Z) and biaxial (X and Y) acceleration.

[0043] Under the acceleration in the Z direction, the mass block drives the coil to move horizontally. Two tunnel magnetoresistive elements parallel to the X direction and two tunnel magnetoresistive elements parallel to the Y direction all sense a change in the magnitude of the magnetic field generated by the coil, outputting a magnetic field change value. This magnetic field change value is the sum of the magnetic field change values ​​sensed by the four tunnel magnetoresistive elements when the coil is moving and the magnetic field change values ​​sensed by the coil when it is stationary. Based on the difference in the magnetic field change values ​​sensed by the four tunnel magnetoresistive elements, the acceleration in the Z direction can be calculated, achieving high-precision detection of triaxial (X, Y, and Z) acceleration.

[0044] The principle of the tunnel magnetoresistive accelerometer in this embodiment is as follows: When the coil is energized (by current or voltage), it generates a magnetic field. This coil is called the excitation coil. The magnetic field generated by the coil is detected by four tunnel magnetoresistive elements. The magnitudes of the magnetic fields detected by the four tunnel magnetoresistive elements are B_5a0, B_5b0, B_5c0, and B_5d0, respectively. When there is acceleration in the X direction (assuming the X-direction acceleration is positive), the mass block moves the excitation coil in the positive X direction. Because the distance between the excitation coil and the tunnel magnetoresistive elements 5a and 5b arranged in the X direction changes, the magnitude of the magnetic field induced by the tunnel magnetoresistive elements 5a and 5b also changes. The magnitudes of the detected magnetic fields are then B_5aX0, B_5b0, B_5c0, and B_5d0, respectively. + B_5bX + The magnitude of the positive X-axis acceleration can be calculated from the magnetic field induction values ​​sensed in 5a and 5b before and after the acceleration begins. That is, when there is positive X-axis acceleration, the output of the positive X-axis magnetic field change is: [(B_5b X+ -B_5b0)-(B_5a X+ -B_5a0)]. Similarly, when there is positive Y-axis acceleration, the output of the positive Y-axis magnetic field change sensed by 5c and 5d is: [(B_5d)]. Y+ -B_5d0)-(B_5c Y+ -B_5c0)], when there is positive Z-axis acceleration, the output of the positive Z-axis magnetic field change sensed by 5a, 5b, 5c and 5d is: [(B_5a Z+ -B_5a0)+(B_5b Z+ -B_5b0)+(B_5c Z+ -B_5c0)+(B_5d Z+ -B_5d0)).

[0045] If the performance of the four tunnel magnetoresistive elements (5a, 5b, 5c, and 5d) is consistent, then the tunnel accelerometer has a differential magnetic field detection structure. A differential magnetic field refers to two sets of magnetic field changes with equal absolute values ​​but opposite signs; the difference between the two is taken as the system's output. The advantages of using a differential magnetic field detection structure are: first, it amplifies the output signal and improves sensitivity; second, it eliminates coupling between accelerations along different axes, thus eliminating common-mode signals. During operation, a micro-accelerometer system experiences accelerations along various axes. Acceleration along either the X or Y axis causes changes in the magnetic field, resulting in output values ​​for both axes, but it's impossible to distinguish which axis's acceleration caused the output. Using differential magnetic field detection, the micro-accelerometer system only outputs a signal under X-axis or Y-axis acceleration, with zero output in other axes. Simultaneously, the magnetic field change is doubled, amplifying the output signal and improving sensitivity. Under differential magnetic field detection conditions, the change in magnetic field along the X(Y) axis is only related to the displacement along the X(Y) axis, and is independent of the displacement along the Y(X) and Z axes, thus eliminating lateral interference along the Y(X) and Z axes. Furthermore, differential magnetic field detection can also eliminate temperature drift and zero-point drift.

[0046] When the acceleration is oblique (the direction of acceleration makes a certain angle with the X-axis or Y-axis), assuming the angles around the X, Y, and Z axes are α, β, and γ respectively, all four tunnel magnetoresistive elements will have outputs under oblique acceleration. Based on the principle described above, the value of B_oblique acceleration can also be calculated. For example, according to cosα = B_xoblique / B_xpositive, cosβ = B_yoblique / B_ypositive, and cosγ = B_zoblique / B_zpositive, the various angles can be calculated.

[0047] In a specific embodiment, the planar shape of the mass block can be rectangular, square, circular, or a regular polygon. The coil is a planar helical coil, and the planar shape of each turn of the coil in the planar helical coil can be rectangular, square, circular, or a regular polygon. The shape of the elastic beam can be selected from various options, such as a straight beam, a folded beam, a double-folded beam, a spiral beam, a crab-shaped beam, or a serpentine beam.

[0048] The tunneling magnetoresistive accelerometer proposed in this invention uses a single coil and four tunneling magnetoresistive elements. The single coil and four tunneling magnetoresistive elements are all placed on the same support structure. The four tunneling magnetoresistive elements are symmetrically distributed around the mass block and the coil to form a differential magnetic field detection structure. The single coil is used as the excitation coil to generate the magnetic field, eliminating the need for a separate magnet. Compared with existing tunneling magnetoresistive accelerometers, it has higher detection sensitivity, a simpler structure, and is easier to integrate in terms of manufacturing process.

[0049] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details described above. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. As long as such combination does not violate the spirit of the embodiments of the present invention, it should also be considered as the content disclosed by the embodiments of the present invention.

Claims

1. An acceleration detection method based on a tunnel magnetoresistive accelerometer, characterized in that, The tunnel magnetoresistive accelerometer includes: a support structure, a mass block, a coil, an elastic beam, and four tunnel magnetoresistive elements. The mass block is connected to the elastic beam, suspended on the support structure, and the coil is located on the surface of the mass block. Four tunneling magnetoresistive elements are disposed on the surface of the support structure and symmetrically distributed around the mass block. Two of the tunneling magnetoresistive elements are located in a straight line parallel to the X direction, and the other two tunneling magnetoresistive elements are located in a straight line parallel to the Y direction. The first ends of the four elastic beams are fixed to the supporting structure, and the second ends of the four elastic beams are connected to the four ends of the mass block. The angle between the elastic beams and the supporting structure is an acute angle. The mass block can move under the action of acceleration in the X, Y, or Z directions to drive the coil to move accordingly; Two tunnel magnetoresistive elements in each of the four tunnel magnetoresistive elements form a differential magnetic field detection structure, which is used to detect changes in the magnetic field generated by changes in the motion state of the induction coil. The acceleration detection method based on a tunnel magnetoresistive accelerometer includes: The mass block, under the action of acceleration in the Z direction, drives the coil to move accordingly. The two tunnel magnetoresistive elements parallel to the X direction and the two tunnel magnetoresistive elements parallel to the Y direction all sense the change in the magnitude of the magnetic field generated by the coil and output the magnetic field change value. This magnetic field change value is the sum of the magnetic field change value sensed by the four tunnel magnetoresistive elements when the coil is in motion and the magnetic field change value sensed by the coil when it is at rest. The acceleration in the Z direction is calculated based on the difference of the magnetic field change value sensed by the four tunnel magnetoresistive elements. The mass block moves under the action of oblique acceleration to drive the coil to move accordingly. The oblique acceleration is calculated based on the output of the four tunnel magnetoresistive elements. Specifically, assuming that the direction of the oblique acceleration makes angles α, β, and γ with the X, Y, and Z axes respectively, the angles α, β, and γ are calculated based on the oblique values ​​of B_x, B_y, and B_z output by the four tunnel magnetoresistive elements. The oblique acceleration is then calculated based on the angles α, β, and γ.

2. The acceleration detection method based on a tunnel magnetoresistive accelerometer according to claim 1, characterized in that, The acceleration in the Z direction is calculated based on the difference in the magnetic field changes induced by the four tunnel magnetoresistive elements. The calculation expression is as follows: (B_5a Z+ -B_5a0)+(B_5b Z+ -B_5b0)+(B_5c Z+ -B_5c0)+(B_5d Z+ -B_5d0); Where B_5a0, B_5b0, B_5c0, and B_5d0 represent the magnitudes of the magnetic fields detected by the four tunnel magnetoresistive elements when there is no acceleration, respectively. Z+ B_5b Z+ B_5c Z+ B_5d Z+ These represent the magnitudes of the magnetic fields detected by the four tunnel magnetoresistive elements under acceleration in the Z direction.

3. The acceleration detection method based on a tunnel magnetoresistive accelerometer according to claim 1, characterized in that, The included angles α, β, and γ are calculated based on the oblique values ​​of B_x, By, and B_z output from the tunnel magnetoresistive element. The calculation expression is as follows: cosα = B_x (oblique direction) / B_x (positive direction); cosβ = B_y oblique direction / B_y positive direction; cosγ = B_z oblique direction / B_z positive direction; Wherein, B_x slant, By slant, and B_z slant represent the values ​​of B_x slant, By slant, and B_z slant output by the four tunnel magnetoresistive elements, respectively; B_x positive, By positive, and B_z positive represent the positive values ​​of B_x, By positive, and B_z outputs of the four tunnel magnetoresistive elements, respectively.

4. The acceleration detection method based on a tunnel magnetoresistive accelerometer according to claim 1, characterized in that, Under the acceleration in the X direction, the mass block drives the coil to move horizontally in the X direction. The two tunnel magnetoresistive elements parallel to the X direction sense the change in the magnitude of the magnetic field generated by the coil and output the magnetic field change value. This magnetic field change value is the difference between the magnetic field change value of the coil in motion state sensed by the two tunnel magnetoresistive elements in the X direction and the magnetic field change value of the coil in stationary state.

5. The acceleration detection method based on a tunnel magnetoresistive accelerometer according to claim 1, characterized in that, Under the acceleration in the Y direction, the mass block drives the coil to move horizontally in the Y direction. The two tunnel magnetoresistive elements parallel to the Y direction sense the change in the magnitude of the magnetic field generated by the coil and output the magnetic field change value. This magnetic field change value is the difference between the magnetic field change value of the coil in motion state sensed by the two tunnel magnetoresistive elements in the Y direction and the magnetic field change value of the coil in stationary state.

6. The acceleration detection method based on a tunnel magnetoresistive accelerometer according to claim 1, characterized in that, The surface of the support structure has a cavity, and the mass block is located above the cavity.

7. The acceleration detection method based on a tunnel magnetoresistive accelerometer according to claim 1, characterized in that, The mass block is centrally symmetrical in shape and has four symmetrical ends; The second ends of the four elastic beams are respectively connected to the four symmetrical ends of the mass block; The distance between each of the four tunnel magnetoresistive elements and the two adjacent elastic beams is equal.

8. The acceleration detection method based on a tunnel magnetoresistive accelerometer according to claim 7, characterized in that, The mass block has a planar shape that is rectangular, square, circular, or a regular polygon.

9. The acceleration detection method based on a tunnel magnetoresistive accelerometer according to claim 7, characterized in that, The coil is a planar spiral coil, and the planar shape of each turn of the coil in the planar spiral coil is a rectangle, square, circle or regular polygon.

10. The acceleration detection method based on a tunnel magnetoresistive accelerometer according to claim 1, characterized in that, The elastic beam can be a straight beam, a folded beam, a double-folded beam, a spiral beam, a crab-shaped beam, or a serpentine beam.

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