阅读说明：本技术 一种高灵敏度低噪声加速度检测装置及方法 (High-sensitivity low-noise acceleration detection device and method ) 是由 王东方 郑路伟 苑文楼 于 2020-07-06 设计创作，主要内容包括：本发明属于加速度测量技术领域,具体涉及一种高灵敏度低噪声加速度检测装置及方法；其中加速度检测装置包括底板、保护外壳、磁屏蔽罩、平行梁振子、主永磁铁、隧道磁电阻传感元件、磁场调制部分、平行梁振子、负反馈永磁铁、负反馈线圈、支撑体和负反馈线圈支撑；是通过梁并联实现高灵敏度、利用磁场高频调制方法实现低1/f噪声和引入电磁力负反馈宽化检测范围的加速度检测装置及方法,能够实现加速度的高灵敏度、低噪声检测。(The invention belongs to the technical field of acceleration measurement, and particularly relates to a high-sensitivity low-noise acceleration detection device and method; the acceleration detection device comprises a bottom plate, a protective shell, a magnetic shield, a parallel beam oscillator, a main permanent magnet, a tunnel magneto-resistor sensing element, a magnetic field modulation part, a parallel beam oscillator, a negative feedback permanent magnet, a negative feedback coil, a support body and a negative feedback coil support; the acceleration detection device and the method realize high sensitivity through beam parallel connection, realize low 1/f noise by utilizing a magnetic field high-frequency modulation method and introduce electromagnetic force negative feedback to widen the detection range, and can realize high sensitivity and low noise detection of acceleration.)

1. A high-sensitivity low-noise acceleration detection device is characterized by comprising a bottom plate (1), a protective shell (2), a magnetic shielding cover (3), a parallel beam oscillator (4), a main permanent magnet (5), a tunnel magneto-resistance sensing element (6), a magnetic field modulation part (7), a parallel beam oscillator (4), a negative feedback permanent magnet, a negative feedback coil, a support body and a negative feedback coil support;

the protective shell (2) is buckled and connected on the bottom plate (1) through bolts, the supporting body is fixed on the bottom plate (1) inside the protective shell (2), the magnetic shielding cover (3) is arranged between the supporting body and the protective shell (2), and the parallel beam vibrator (4) is positioned in the middle of the supporting body;

the parallel beam vibrator (4) comprises a frame (41) and two parallel beam units which are arranged in a bilateral symmetry mode, the two parallel beam units are spliced together and then fixed in the frame (41), each parallel beam unit comprises a transverse parallel beam (42), a longitudinal parallel beam (43) and a negative feedback magnet support (44), the transverse parallel beam (42) is fixed to the upper end and the lower end of the negative feedback magnet support (44) respectively, and one longitudinal parallel beam (43) is fixed to one side of the negative feedback magnet support (44);

an upper negative feedback permanent magnet (9) and a lower negative feedback permanent magnet (8) are respectively fixed on the upper surface and the lower surface of the negative feedback magnet support (44), an upper negative feedback coil (11) and a lower negative feedback coil (10) are respectively arranged on the peripheries of the upper negative feedback permanent magnet (9) and the lower negative feedback permanent magnet (8), and the upper negative feedback coil (11) and the lower negative feedback coil (10) are respectively connected to the support body through an upper negative feedback coil support (14) and a lower negative feedback coil support (15) through bolts;

a main permanent magnet (5) is fixed at the joint of negative feedback magnet supports (44) in two parallel beam units in a parallel beam vibrator (4), a magnetic field modulation part (7) and a circuit part support (17) are sequentially fixed on a support body at the rear side of the main permanent magnet (5), a tunnel magneto-resistance sensing element (6) and a circuit part (16) are respectively fixed at the front end and the rear end of the circuit part support (17) between the magnetic field modulation part (7) and the circuit part support (17), and the tunnel magneto-resistance sensing element (6) is connected with the circuit part (16) through a wire;

the magnetic field modulation part (7) comprises a cantilever beam (704), a high-permeability soft magnetic film (7)08 is pasted below the front end of the cantilever beam (704), the high-permeability soft magnetic film (7)08 faces the tunneling magneto-resistance sensing element (6), a metal electrode layer I (703), a piezoelectric layer I (702) and a metal electrode layer II (701) are sequentially pasted above the rear end of the cantilever beam (704), and a metal electrode layer III (705), a piezoelectric layer II (706) and a metal electrode layer IV (707) are sequentially pasted below the rear end of the cantilever beam (704);

the first metal electrode layer (703), the second metal electrode layer (701), the third metal electrode layer (705) and the fourth metal electrode layer (707) are all connected with a modulation circuit in the circuit part (16) through leads;

a negative feedback driving circuit in the circuit part (16) is respectively connected with the upper negative feedback coil (11) and the lower negative feedback coil (10);

a first power signal hole (201) is formed in the protective shell (2), a second power signal hole (301) is formed in the magnetic shield (3), and a third power signal hole (1201) is formed in the support body.

2. The acceleration detection device with high sensitivity and low noise according to claim 1, wherein the support comprises an upper support (12) and a lower support (13), wherein the lower support (13), the parallel beam vibrator (4) and the upper support (12) are sequentially fixed on the bottom plate (1) inside the protective housing (2) from bottom to top.

3. The acceleration detection device with high sensitivity and low noise according to claim 2, characterized in that the parallel beam vibrator (4) is located between the upper support (12) and the lower support (13), and the bolt is screwed into the bottom plate (1) to fasten after passing through the upper support (12), the parallel beam vibrator (4) and the lower support (13) in sequence.

4. A high sensitivity low noise acceleration sensing device according to claim 3, characterized in that said transversal parallel beams (42) comprise n beam elements horizontally arranged and fixed together, and said longitudinal parallel beams (43) comprise n beam elements vertically arranged and fixed together, where n is an integer other than (0), and the number of beam elements of the transversal parallel beams (42) is the same as the number of beam elements of the longitudinal parallel beams (43).

5. The acceleration detecting device of claim 4, wherein said beam unit is formed by two beams arranged side by side and fixed together.

6. The acceleration sensing device of claim 5, wherein said two negative feedback magnet supports (44) of two parallel beam units are fixed together, the transverse beam (42) at the top of each parallel beam unit is fixed above the frame (41), the transverse beam (42) at the bottom of each parallel beam unit is fixed below the frame (41), and the longitudinal beams (43) at the sides of the two parallel beam units are fixed at the left and right sides of the frame (41).

7. The acceleration detecting device with high sensitivity and low noise according to claim 6, wherein the upper negative feedback permanent magnet (9) and the lower negative feedback permanent magnet (8) are negative feedback permanent magnets with the same shape, mass and magnetization.

8. The acceleration detecting device with high sensitivity and low noise according to claim 7 is characterized in that the four corners of the upper negative feedback coil support (14) and the four corners of the lower negative feedback coil support (15) are respectively fixed on the upper support body (12) and the lower support body (13) through a positioning screw (18) and a positioning nut (19).

9. A method for detecting acceleration by using the high-sensitivity low-noise acceleration detecting device of claim 1, comprising the steps of:

the method comprises the following steps of firstly, mounting the acceleration detection device on a measured object;

step two, calibrating the acceleration detection device:

the circuit part (16) is externally connected with a voltmeter, meanwhile, a modulation circuit in the circuit part (16) is externally connected with a power supply, then the measured object is accelerated to move at different positions and poses, and the position and the pose of the measured object corresponding to the maximum final output voltage value of the tunnel magneto-resistance sensing element (6) passing through the circuit part (16) are selected as the position and the pose for the experiment;

step three, determining the initial output voltage value of the tunnel magnetoresistance sensing element (6):

when the object to be measured is in situ fixed, the voltage value displayed by the voltmeter externally connected with the circuit part (16) is the initial output voltage value of the tunnel magneto-resistance sensing element (6), and is marked as U_{First stage}；

Step four, enabling the object to be measured to carry out acceleration motion according to the position and the pose for the experiment determined in the step two, and when the object to be measured generates acceleration a_cWhen the vibration is carried out, the upper negative feedback permanent magnet (9) and the lower negative feedback permanent magnet (8) which are simultaneously used as mass blocks sense acceleration to generate the action of inertia force to drive the parallel beam oscillator (4) to vibrate together, the relative position of the main permanent magnet (5) and the fixed tunnel magneto-resistance sensing element (6) in the vibration is changed, namely the magnetic field of the space position of the tunnel magneto-resistance sensing element (6) is changed, the changed magnetic field is detected by the tunnel magneto-resistance sensing element (6) and outputs a voltage signal which is in direct proportion to the magnitude of the magnetic field, after the voltage signal passes through a circuit part (16), one path of the voltage signal is used as a feedback signal and flows to the upper negative feedback coil (11) and the lower negative feedback coil (10) to generate electromagnetic force to enable the parallel beam oscillator (4) to be kept at a balance position, the other path is output as a final, the voltage value minus the initial value of the tunnel magnetoresistive sensing element (6)Initial output voltage value U_{First stage}Namely the final output voltage U of the acceleration detection device;

fifthly, the tunnel magneto-resistance sensing element (6) finally outputs the voltage U and the acceleration a of the object to be measured_cIn linear relation, acceleration a of the object to be measured_cThe final output voltage U of the tunnel magneto-resistance sensing element (6) and the parameter K of the acceleration detection device can be obtained, and the formula is as follows:

a_c＝KU

wherein:

wherein: m is equivalent sensitive mass, namely the mass sum of the parallel beam vibrator (4), the main permanent magnet (5) and all negative feedback permanent magnets, K_MEquivalent spring rate, K, for the mechanically vibrating part_HThe magnetic field change rate of a certain component of the magnetic field of the main permanent magnet (5) in an approximate linear change area, G is the magnetic field modulation efficiency coefficient of the magnetic field modulation part (7), and K_TMRFor the field-voltage conversion coefficient, K, of the tunnel magnetoresistive element (6)_AIs the voltage amplification factor, G, of the amplifying circuit module in the circuit part (16)_MDMIs the modulation-demodulation coefficient, K, of the demodulation circuit in the circuit part (16)_NFIs the overall electromagnetic force negative feedback coefficient.

Technical Field

The invention belongs to the technical field of acceleration measurement, and particularly relates to a high-sensitivity low-noise acceleration detection device and method.

Background

With the rapid development of mechanical manufacturing technology, electronic circuit technology and sensor technology, acceleration detection plays an increasingly important role in the production and life of people. Currently, accelerometers have been put to practical use and commercialized in many fields, such as information technology, bioengineering, inertial guidance, automotive electronics, consumer electronics, aerospace, seismic surveying, motion control, and medical care. The development of the high-performance acceleration detection device has a very high development prospect and market application.

The tunneling magneto-resistance technology is more and more emphasized as a fourth-generation magnetic sensing technology in recent years, and compared with other magneto-resistance effects, the tunneling magneto-resistance effect has the advantages of larger resistance change rate, better temperature stability, higher sensitivity, better linearity and lower power consumption. The magnetic sensor based on the tunnel magnetoresistance effect has more excellent performance than the current mainstream magnetic sensor, namely a Hall sensor, and is beneficial to the development of a high-performance acceleration detection device based on the tunnel magnetoresistance effect.

The acceleration detection mainly uses an accelerometer to detect the acceleration of the movement of an object. According to different detection modes, the existing accelerometers can be classified into various types such as capacitance type, piezoelectric type, piezoresistive type, resonant type, tunneling current type and optical fiber type, but still cannot achieve high sensitivity in a large detection range, and meanwhile, the 1/f noise level is high, so that the actual requirements cannot be met, for example, although the tunneling current type accelerometer can achieve high sensitivity, the detection range is very narrow, and the actual application of the tunneling current type accelerometer is severely limited, so that the development of an acceleration detection device with high sensitivity, low 1/f noise level and large detection range becomes particularly important.

Disclosure of Invention

In order to overcome the problems, the invention provides a high-sensitivity low-noise acceleration detection device and method, which realize high sensitivity by connecting beams in parallel, realize low 1/f noise by using a magnetic field high-frequency modulation method and introduce electromagnetic force negative feedback to widen the detection range, and can realize high-sensitivity and low-noise detection of acceleration.

A high-sensitivity low-noise acceleration detection device comprises a bottom plate 1, a protective shell 2, a magnetic shield 3, a parallel beam oscillator 4, a main permanent magnet 5, a tunnel magneto-resistance sensing element 6, a magnetic field modulation part 7, a parallel beam oscillator 4, a negative feedback permanent magnet, a negative feedback coil, a support body and a negative feedback coil support;

the protective shell 2 is buckled and bolted on the bottom plate 1, the supporting body is fixed on the bottom plate 1 in the protective shell 2, a magnetic shielding cover 3 is arranged between the supporting body and the protective shell 2, and the parallel beam vibrator 4 is positioned in the middle of the supporting body;

the parallel beam vibrator 4 comprises a frame 41 and two parallel beam units which are arranged in a bilateral symmetry mode, the two parallel beam units are spliced together and then fixed in the frame 41, each parallel beam unit comprises a transverse parallel beam 42, a longitudinal parallel beam 43 and a negative feedback magnet support 44, the transverse parallel beam 42 is fixed to the upper end and the lower end of the negative feedback magnet support 44 respectively, and one longitudinal parallel beam 43 is fixed to one side of the negative feedback magnet support 44;

an upper negative feedback permanent magnet 9 and a lower negative feedback permanent magnet 8 are respectively fixed on the upper surface and the lower surface of the negative feedback magnet support 44, an upper negative feedback coil 11 and a lower negative feedback coil 10 are respectively arranged on the peripheries of the upper negative feedback permanent magnet 9 and the lower negative feedback permanent magnet 8, and the upper negative feedback coil 11 and the lower negative feedback coil 10 are respectively connected to the support body through an upper negative feedback coil support 14 and a lower negative feedback coil support 15 in a bolt mode;

a main permanent magnet 5 is fixed at the joint of negative feedback magnet supports 44 in two parallel beam units in the parallel beam vibrator 4, a magnetic field modulation part 7 and a circuit part support 17 are sequentially fixed on a support body at the rear side of the main permanent magnet 5, a tunnel magneto-resistance sensing element 6 and a circuit part 16 are respectively fixed at the front end and the rear end of the circuit part support 17 between the magnetic field modulation part 7 and the circuit part support 17, and the tunnel magneto-resistance sensing element 6 is connected with the circuit part 16 through a lead;

the magnetic field modulation part 7 comprises a cantilever beam 704, a high-permeability soft magnetic film 708 is attached to the lower portion of the front end of the cantilever beam 704, the high-permeability soft magnetic film 708 faces the tunneling magneto-resistance sensing element 6, a metal electrode layer I703, a piezoelectric layer I702 and a metal electrode layer II 701 are sequentially attached to the upper portion of the rear end of the cantilever beam 704, and a metal electrode layer III 705, a piezoelectric layer II 706 and a metal electrode layer IV 707 are sequentially attached to the lower portion of the rear end of the cantilever beam 704;

the first metal electrode layer 703, the second metal electrode layer 701, the third metal electrode layer 705 and the fourth metal electrode layer 707 are all connected with the modulation circuit in the circuit part 16 through wires;

a negative feedback drive circuit in the circuit section 16 is connected to the upper negative feedback coil 11 and the lower negative feedback coil 10, respectively;

the protective shell 2 is provided with a first power signal hole 201, the magnetic shield 3 is provided with a second power signal hole 301, and the support body is provided with a third power signal hole 1201.

The supporter include last supporter 12 and lower supporter 13, wherein lower supporter 13, parallel beam oscillator 4 and last supporter 12 fix in proper order on the inside bottom plate 1 of protecting sheathing 2 from bottom to top.

The parallel beam vibrator 4 is positioned between the upper support body 12 and the lower support body 13, and the bolt sequentially penetrates through the upper support body 12, the parallel beam vibrator 4 and the lower support body 13 and then is screwed into the bottom plate 1 for fastening.

The transverse parallel beams 42 include n beam units, the n beam units are horizontally arranged and fixed together, the longitudinal parallel beams 43 include n beam units, the n beam units are vertically arranged and fixed together, wherein n is an integer different from 0, and the number of the beam units of the transverse parallel beams 42 is the same as that of the longitudinal parallel beams 43.

The beam unit is formed by arranging two beams side by side and fixing the two beams together.

The two negative feedback magnet supports 44 of the two parallel beam units are fixed together, the transverse beam 42 at the top end of each parallel beam unit is fixed above the frame 41, the transverse beam 42 at the bottom end of each parallel beam unit is fixed below the frame 41, and the longitudinal beams 43 at the side surfaces of the two parallel beam units are respectively fixed at the left side and the right side of the frame 41.

The upper negative feedback permanent magnet 9 and the lower negative feedback permanent magnet 8 are negative feedback permanent magnets with the same shape, mass and magnetization intensity.

The four corners of the upper negative feedback coil support 14 and the four corners of the lower negative feedback coil support 15 are respectively fixed on the upper support body 12 and the lower support body 13 through a positioning screw 18 and a positioning nut 19.

A method for detecting acceleration by using the high-sensitivity low-noise acceleration detection device comprises the following steps:

the method comprises the following steps of firstly, mounting the acceleration detection device on a measured object;

step two, calibrating the acceleration detection device:

externally connecting a voltmeter to the circuit part 16, then enabling the measured object to perform accelerated motion at different positions and poses, and selecting the position and pose of the measured object corresponding to the maximum final output voltage value of the tunnel magnetoresistive sensing element 6 after passing through the circuit part 16 as the position and pose for the experiment;

step three, determining the initial output voltage value of the tunnel magnetoresistance sensing element 6:

when the object to be measured is in place, the voltage value displayed by the voltmeter externally connected with the circuit part 16 is the initial output voltage value of the tunnel magneto-resistance sensing element 6 and is marked as U_{First stage}；

Step four, enabling the object to be measured to carry out acceleration motion according to the position and the pose for the experiment determined in the step two, and when the object to be measured generates acceleration a_cWhen in use, the upper negative feedback permanent magnet 9 and the lower negative feedback permanent magnet 8 which are used as mass blocks sense acceleration and generate the action of inertia force to drive the parallel beam vibrator 4 to vibrate together, the relative position of the main permanent magnet 5 and the fixed tunnel magneto-resistance sensing element 6 in vibration changes, that is, the magnetic field at the spatial position of the tunneling magneto-resistive sensing element 6 changes, the changed magnetic field is detected by the tunneling magneto-resistive sensing element 6, and a voltage signal proportional to the magnitude of the magnetic field is output, after the voltage signal passes through the circuit part 16, one path of the voltage signal is used as a feedback signal and flows to the upper negative feedback coil 11 and the lower negative feedback coil 10 to generate electromagnetic force so as to keep the parallel beam oscillator 4 at a balance position, the other path of the voltage signal is output as a final voltage signal, the voltage value is detected by an external voltmeter, and the initial output voltage value U of the tunnel magneto-resistance sensing element 6 is subtracted from the voltage value._{First stage}Namely the final output voltage U of the acceleration detection device;

fifthly, the tunnel magneto-resistance sensing element 6 finally outputs the voltage U and the acceleration a of the object to be measured_cIn linear relation, acceleration a of the object to be measured_cThe final output voltage U of the tunnel magnetoresistive sensing element 6 and the parameter K of the acceleration detection apparatus can be obtained, and the formula is as follows:

a_c＝KU

wherein:

wherein: m is equivalent sensitive mass, namely the mass sum of the parallel beam vibrator 4, the main permanent magnet 5 and all negative feedback permanent magnets, K_MEquivalent spring rate, K, for the mechanically vibrating part_HThe magnetic field change rate of a certain component of the magnetic field of the main permanent magnet 5 in an approximately linear change region, G is the magnetic field modulation efficiency coefficient of the magnetic field modulation part 7, K_TMRFor the field-voltage conversion coefficient, K, of the tunnel magnetoresistive element 6_AIs the voltage amplification factor, G, of the amplifying circuit block in the circuit part 16_MDMIs the modulation-demodulation coefficient, K, of the demodulation circuit in circuit part 16_NFIs the overall electromagnetic force negative feedback coefficient.

The invention has the beneficial effects that:

1. the sensitivity is high: the parallel beam vibrator adopts a multi-beam parallel structure form by only superposing a linear system on the structural layer surface, and the detection sensitivity can be effectively improved compared with the traditional beam structure. Whether the influence of the connecting part between the parallel beams on the sensitivity is considered is determined according to the actual situation, and if the coupling strength between the parallel beams is extremely strong, namely the deformation of the connecting part between the parallel beams can be ignored, the influence of the connecting part between the parallel beams on the sensitivity does not need to be considered; otherwise, it needs to be considered. And secondly, the negative feedback permanent magnet is used as a mass block, so that the sensitive quality can be increased to improve the sensitivity.

2. Low 1/f noise level: the 1/f noise level is reduced by using a magnetic field modulation method, the cantilever beam is driven at high frequency by a piezoelectric technology, a high-permeability film attached to the tail end of the cantilever beam vibrates at high frequency at the same frequency, a low-frequency vibration magnetic field detected by the tunnel magneto-resistance sensing element is modulated at high frequency, and the generated modulation signal is demodulated at the later stage to obtain acceleration information, so that the 1/f noise level can be effectively reduced, and the acceleration sensing precision is improved.

3. The detection range is wide: the negative feedback permanent magnet and the negative feedback coil interact to generate negative feedback electromagnetic force to keep the parallel beam vibrator at a balance position so as to increase the detection range.

4. The precision is high: the parallel beam vibrator is fixedly connected around, so that the rigidity in a non-detection direction is increased, and the influence of the parallel beam vibrator on the acceleration detection in a sensitive direction is reduced. And negative feedback permanent magnets with the same shape, quality and magnetization are fixed on the upper surface and the lower surface of the supporting parts at the left side and the right side of the parallel beam vibrator, so that the gravity center of a structure formed by combining the parallel beam vibrator and the negative feedback permanent magnets is positioned at the geometric center of the parallel beam vibrator, and the influence of cross axis sensitivity and torsion sensitivity on the main shaft detection sensitivity is effectively reduced. The polarization direction of the negative feedback permanent magnet is perpendicular to the detection direction of the tunnel magneto-resistance sensing element so as to reduce the influence of the negative feedback permanent magnet on the acceleration detection precision, the polarization directions of the two negative feedback permanent magnets on the upper surface and the lower surface of the same side of the parallel beam oscillator are opposite, and the polarization directions of the two negative feedback permanent magnets on the same surface of the parallel beam oscillator are opposite so as to weaken the influence of the magnetic field of the negative feedback permanent magnet on the tunnel magneto-resistance sensing element.

5. The anti-interference capability is strong: the whole structure is arranged in the magnetic shielding cover, so that the external electromagnetic interference can be effectively reduced. Secondly, the TMR chip adopted adopts a Wheatstone bridge structure, so that the common-mode signal interference can be effectively inhibited.

6. The response speed is high: a PID control module is designed in the circuit part, so that the response speed can be effectively improved, and meanwhile, the quick response speed is one of the requirements of the designed acceleration detection device.

In conclusion, the invention improves the sensitivity and the detection range of the acceleration detection device, reduces the 1/f noise level, has high precision, strong anti-interference capability, high response speed and good practicability, and is suitable for high-precision inertial sensing systems and related applications thereof.

Drawings

FIG. 1 is an isometric view of a high sensitivity, low noise acceleration detection apparatus of the present invention;

FIG. 2 is a bottom view of the general structure of the device of the present invention;

FIG. 3 is a front view of the general structure of the apparatus of the present invention;

FIG. 4 is a cross-sectional view of the general structure of the apparatus of the present invention taken along plane A-A;

FIG. 5 is a schematic diagram of the structure of the magnetic field modulation part of the device of the present invention;

FIG. 6 is a cross-sectional view of the general structure of the device of the present invention taken along the plane B-B;

FIG. 7 is a cross-sectional view of the general structure of the device of the present invention taken along plane C-C;

FIG. 8 is an isometric view of the main internal structure of example 1 of the present invention;

FIG. 9 is an isometric view of the main internal structure of example 2 of the present invention;

FIG. 10 is a schematic diagram of the present invention for detecting acceleration.

Fig. 11 is a schematic structural view of a parallel beam transducer according to embodiment 1 of the present invention.

Fig. 12 is a schematic structural view of a parallel beam transducer according to embodiment 2 of the present invention.

Wherein: 1 bottom plate, 2 protective shell, 201 power signal hole I, 202 bottom plate screw, 3 magnetic shield, 301 power signal hole II, 4 parallel beam vibrator, 40 connecting screw, 41 frame, 42 horizontal parallel beam, 43 longitudinal parallel beam, 44 negative feedback magnet support, 5 main permanent magnet, 6 tunnel magneto resistance sensing element, 7 magnetic field modulation part, 701 metal electrode layer II, 702 piezoelectric layer I, 703 metal electrode layer I, 704 cantilever beam, 705 metal electrode layer three, 706 piezoelectric layer two, 707 metal electrode layer four, 708 high magnetic permeability soft magnetic film, 8 lower negative feedback permanent magnet, 9 upper negative feedback permanent magnet, 10 lower negative feedback coil, 11 upper negative feedback coil, 12 upper supporter, 1201 power signal hole three, 13 lower supporter, 14 upper negative feedback coil supporter, 15 lower negative feedback coil supporter, 16 circuit part, 17 circuit part supporter, 18 positioning screw, 19 positioning nut.

Detailed Description