Accelerometer

Abstract

The present invention provides an accelerometer, comprising a base, a sensing unit provided on the base, and two anchor points for fixing the base. The sensing unit comprises: an outer coupling unit, the outer coupling unit is stacked on the base; seesaw structures, wherein two seesaw structures are provided and arranged on the inner side of the outer coupling unit, and the two seesaw structures are arranged symmetrically about the center; inner coupling units, wherein two inner coupling units are provided and arranged on the inner side of the outer coupling unit, and the two inner coupling units are arranged symmetrically about a line connecting the two anchor points; and proof masses, wherein the proof masses are fixed to the outer coupling unit and / or the inner coupling units. The accelerometer also comprises out-of-plane detection devices, wherein the out-of-plane detection devices are respectively arranged in a base area directly facing the outer coupling unit and a base area directly facing the inner coupling units. The accelerometer of the present invention can make all the displacements of out-of-plane detection capacitors become linear displacements, greatly improving the linearity of acceleration detection.

Description

Accelerometer TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-mechanical structure, and in particular to an accelerometer. BACKGROUND

[0002] The accelerometer is an instrument for measuring linear acceleration of a carrier. As shown in FIG. 1, a seesaw out-of-plane accelerometer mainly includes a base (not shown in the figure), a sensing unit arranged on the base, and an anchor point 201 fixed to the base and located at the same level as the sensing unit. The sensing unit mainly includes a torsion spring 202 fixed between the anchor points and a proof mass 203. When the accelerometer is subjected to an out-of-plane (Z-direction) acceleration, the asymmetric proof mass 203 (M1) drives the torsion spring 202 to rotate around the rotation axis 204, which causes the out-of-plane displacement of the region 205 corresponding to the capacitor plate, and a differential capacitor is formed by placing a capacitor plate above or below the region 205 corresponding to the capacitor plate. Thus, the acceleration change can be obtained by detecting the change in the capacitor. As shown in FIG. 2, due to the asymmetric structure of the accelerometer, i.e., the mass center point 206 is not located on the rotation axis 204, the accelerometer will swing in the in-plane (X-direction) under the action of the X-direction acceleration.

[0003] To solve the above problems, a structure with two seesaws is disclosed in the patent application (US20200018777A) of Murata Company. The main body of the rotating proof mass is on the seesaw structure, and a rigid body is added externally as a coupling structure and as a linear mass. When subjected to an out-of-plane acceleration, the linear mass moves linearly in the out-of-plane direction. This structure sets the detection plate far from the rotation axis to ensure the gain of the rotation to the capacitor change and eliminates the swing in the X-axis direction (IP1-axis direction), but cannot suppress the rotation of the two seesaws around the Z-axis (OP-axis) and the rotation around the X-axis (IP1-axis) in the same direction.

[0004] A multi-axis accelerometer is disclosed in the patent application (US20200132716A1) of ADI Company. The out-of-plane accelerometer adopts a butterfly structure, i.e., the inner coupling structure realizes the motion coupling of the two seesaw structures, which can suppress the in-plane rotation of the single seesaw structure and the rotation around the rotation axis in the same direction. Compared with the structure of Murata Company, the accelerometer does not have a linear proof mass as an outer coupling structure, so it has poor suppression ability for the reverse rotation of the two seesaw structures around the Z-axis.

[0005] In summary, the accelerometer in the related art cannot make the displacement of the out-of-plane capacitor substrate all become linear displacement, which leads to poor linearity of the acceleration detection of the accelerometer. TECHNICAL PROBLEM

[0006] The application aims to provide an accelerometer which improves the linearity of acceleration detection. Technical solutions

[0007] To achieve the above-mentioned purpose, the application provides an accelerometer, which comprises a base, a sensing unit arranged on the base, and two anchor points fixed to the base and located at the same level as the sensing unit, the two anchor points being arranged in a facing and spaced manner; the sensing unit comprises:

[0008] an outer coupling unit, which is stacked on the base;

[0009] a seesaw structure, which comprises two and is arranged in a spaced manner on the inner side of the outer coupling unit, the two seesaw structures being arranged in a central symmetry manner;

[0010] an inner coupling unit, which comprises two and is arranged in a spaced manner on the inner side of the outer coupling unit, the two inner coupling units being arranged in a symmetry manner about the connecting line of the two anchor points and being located on the opposite sides of the anchor points respectively; each seesaw structure is elastically connected to the outer coupling unit, the two inner coupling units and the other seesaw structure respectively;

[0011] a proof mass, which is fixed to the outer coupling unit and / or the inner coupling unit; and

[0012] the accelerometer further comprises an out-of-plane detection device, which is arranged in a base area opposite to the outer coupling unit and a base area opposite to the inner coupling unit respectively, the out-of-plane detection device being used for detecting the linear motion of the outer coupling unit and / or the inner coupling unit in a first direction in a capacitive detection manner.

[0013] Preferably, the seesaw structure is arranged in a nested manner.

[0014] Preferably, the two anchor points are located in the middle area of the outer coupling unit.

[0015] Preferably, the outer coupling unit comprises a support part in a rectangular ring shape, two counterweight parts arranged in a spaced manner, and two connecting parts for connecting the two counterweight parts to the opposite sides of the support part respectively, the counterweight parts being arranged in a spaced manner with the support part and the seesaw structure respectively; the counterweight part also serves as a proof mass.

[0016] Preferably, each of the seesaw structures comprises two torsion springs spaced apart from each other and elastic members respectively fixed to the two torsion springs, one end of the two torsion springs close to each other is respectively fixed to the corresponding anchor point, and the other end of the two torsion springs away from each other is respectively connected to the elastic member; the elastic member in each of the seesaw structures is respectively and elastically connected to the outer coupling unit, the two inner coupling units, and the elastic member in the other seesaw structure, and each of the seesaw structures is spaced apart from the elastic member in the outer coupling unit, the two inner coupling units, and the other seesaw structure.

[0017] Preferably, the elastic member in each of the seesaw structures comprises a first elastic beam and a second elastic beam respectively fixed to opposite sides of the connecting portion, a rotating arm fixed to one end of the first elastic beam away from the connecting portion, a first extension portion fixed to one end of the second elastic beam away from the connecting portion, a fixed portion protruding from the rotating arm to the first extension portion, a second extension portion protruding from the rotating arm towards the first extension portion, a third elastic beam connected to one end of the rotating arm away from the first elastic beam and one side of one of the inner coupling units away from the first elastic beam, a bending portion formed by bending one end of the first extension portion away from the second elastic beam around the other inner coupling unit, a fourth elastic beam connected to one end of the bending portion away from the first extension portion and one side of the corresponding inner coupling unit away from the second elastic beam, and a fifth elastic beam connected to the bending portion, the second extension portion is spaced apart from the fixed portion and the bending portion respectively, and the fifth elastic beam is located between and spaced apart from the two anchor points; one end of the two torsion springs in each of the seesaw structures away from each other is respectively connected to the corresponding rotating arm and the first extension portion, and is spaced apart from the fixed portion, the second extension portion, and the bending portion respectively, one end of the two torsion springs in the seesaw structure close to each other is respectively fixed to the corresponding anchor point, and the fifth elastic beam in each of the seesaw structures is connected to the fifth elastic beam in the other seesaw structure.

[0018] Preferably, one end of each of the anchor points away from the other anchor point is connected to the corresponding two torsion springs through an extension arm, the extension arm is located between and spaced apart from the corresponding second extension portion and the bending portion respectively.

[0019] Preferably, the base comprises a base plate and a cover fixed to the base plate and together enclosing a receiving space, and the sensing unit is arranged in the receiving space; and the out-of-plane detection device comprises a first capacitor plate fixed to a region of the base plate or the cover opposite to the outboard coupling unit, and a second capacitor plate fixed to a region of the base plate or the cover opposite to the inboard coupling unit.

[0020] Preferably, the accelerometer further comprises an in-plane detection device arranged on the outboard coupling unit, which is configured to detect linear motion of the outboard coupling unit in a second direction and / or in a third direction by capacitive detection; and the first direction, the second direction and the third direction are perpendicular to each other.

[0021] Preferably, the in-plane detection device comprises a plurality of X-axis in-plane detection units for detecting linear motion of the outboard coupling unit in the second direction, and / or a plurality of Y-axis in-plane detection units for detecting linear motion of the outboard coupling unit in the third direction. Advantages

[0022] Compared with the related art, the overall structure of the accelerometer is supported by two opposite seesaw structures, the outboard coupling structure is coupled to the outer side of the two seesaw structures, the inboard coupling structure is coupled to the inner side of the seesaw structures, and the two seesaw structures are arranged in a central symmetry, and the two inboard coupling units are symmetrically arranged about the connecting line of the two anchor points and located on opposite sides of the anchor points, which to some extent suppresses the rotation of the seesaw structure about the axis perpendicular to the plane of the seesaw structure, reduces the cross-coupling of the seesaw structure, and the proof mass of the accelerometer is distributed on the outboard coupling unit and / or the inboard coupling unit. When the out-of-plane acceleration perpendicular to the plane axis arrives, the outboard coupling unit and the inboard coupling unit on both sides of the seesaw structure move differentially relative to the base, causing the detection capacitor in the out-of-plane detection device to form a parallel-plate capacitor with the sensing unit and change differentially. In other words, when subjected to the out-of-plane acceleration, the mass of the outboard coupling unit will move in the direction of the acceleration due to its larger mass, and the mass of the inboard coupling unit will move in the opposite direction of the acceleration due to its smaller mass. As a result, the capacitance corresponding to the outboard coupling unit will increase, and the capacitance corresponding to the inboard coupling unit will decrease, thereby forming a differential capacitance, and the out-of-plane acceleration can be detected by detecting the change in the detection capacitor. This structure makes the displacement of the out-of-plane detection capacitor all linear displacement, greatly improving the linearity of the acceleration detection. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings described below only illustrate some of the embodiments of the present application, and are not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0024] Fig. 1 is a structural schematic diagram of an accelerometer provided by the related art;

[0025] Fig. 2 is a motion state schematic diagram of an accelerometer provided by the related art;

[0026] Fig. 3 is a structural schematic diagram of an accelerometer provided by an embodiment of the present application;

[0027] Fig. 4 is a detection mode schematic diagram of an accelerometer provided by an embodiment of the present application;

[0028] Fig. 5 is a modularized sectional schematic diagram of an accelerometer provided by an embodiment of the present application;

[0029] Fig. 6 is a structural schematic diagram of an accelerometer provided by an embodiment of the present application.

[0030] In the drawings, 100, accelerometer; 1, sensing unit; 11, outer coupling unit; 111, support part; 112, counterweight part; 113, connecting part; 12, seesaw structure; 121, torsion spring; 122, elastic piece; 1221, first elastic beam; 1222, second elastic beam; 1223, rotating arm; 1224, first extension part; 1225, fixed part; 1226, second extension part; 1227, third elastic beam; 1228, bending part; 1229, fourth elastic beam; 12210, fifth elastic beam; 13, inner coupling unit; 2, anchor point; 21, extension arm; 3, in-plane detection device; 31, X-axis in-plane detection unit; 32, Y-axis in-plane detection unit; 4, base; 40, accommodation space; 41, base plate; 42, cavity cover; 5, first capacitor plate; 6, second capacitor plate. Embodiment of the present application

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, and not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0032] Embodiment one

[0033] The Z axis in FIG. 3 is the first direction, the X axis is the second direction, the Y axis is the third direction, and the dashed box is the area of the capacitor plate on the base 4; in combination with FIG. 3, an accelerometer 100 is provided, which includes the base 4, the sensing unit 1 arranged on the base 4, and two anchor points 2 fixed to the base 4 and located at the same level as the sensing unit 1, and the two anchor points 2 are arranged in a facing and spaced manner.

[0034] The base 4 includes a base plate 41 and a cover 42 arranged on the base plate 41 and together enclosing a receiving space; the sensing unit 1 is arranged in the receiving space 40.

[0035] Specifically, the sensing unit 1 includes an outer coupling unit 11, a seesaw structure 12, an inner coupling unit 13, and a proof mass.

[0036] The outer coupling unit 11 is arranged on the base 4; the seesaw structure 12 includes two and is arranged on the inner side of the outer coupling unit 11, and the two seesaw structures 12 are arranged in a central symmetric manner; the inner coupling unit 13 includes two and is arranged on the inner side of the outer coupling unit 11, respectively, the two inner coupling units 13 are arranged symmetrically about the connecting line of the two anchor points 2 and are located on the opposite sides of the anchor points 2, respectively; each seesaw structure 12 is elastically connected to the outer coupling unit 11, the two inner coupling units 13, and the other seesaw structure 12, respectively; the proof mass is fixed to the outer coupling unit 11 and / or the inner coupling unit 13.

[0037] The outer coupling unit 11 includes a support portion 111 in the shape of a rectangular ring, two counterweight portions 112 spaced from each other, and two connecting portions 113 respectively connecting the two counterweight portions 112 to the opposite sides of the support portion 111, the counterweight portions 112 are arranged spaced from the support portion 111 and the seesaw structure 12; the counterweight portion 112 also serves as the proof mass, that is, the counterweight portion 112 is not only a part of the outer coupling unit 11, but also directly serves as the proof mass.

[0038] In addition, the support portion 111, the counterweight portion 112, and the connecting portion 113 in the outer coupling unit 11 also belong to part of the seesaw structure 12.

[0039] Each seesaw structure 12 comprises two torsion springs 121 spaced apart from each other, and elastic members 122 fixed to the two torsion springs 121 respectively, the two torsion springs 121 are fixed to the corresponding anchor points 2 at the ends close to each other respectively, and the two torsion springs 121 are connected to the elastic members 122 at the ends away from each other respectively; the elastic members 122 in each seesaw structure 12 are respectively elastically connected to the elastic members 122 in the other seesaw structure 12, the elastic members 122 in each seesaw structure 12 are respectively elastically connected to the outside coupling unit 11, the two inside coupling units 13, and the elastic members 122 in the other seesaw structure 12, and the elastic members 122 in each seesaw structure 12 are spaced apart from the elastic members 122 in the outside coupling unit 11, the two inside coupling units 13, and the other seesaw structure 12 respectively.

[0040] The elastic members 122 in each seesaw structure 12 comprise first and second elastic beams 1221 and 1222 fixed to opposite sides of the connecting portion 113 respectively, a rotating arm 1223 fixed to the end of the first elastic beam 1221 away from the connecting portion 113, a first extension 1224 fixed to the end of the second elastic beam 1222 away from the connecting portion 113, a fixed portion 1225 protruding from the rotating arm 1223 to the first extension 1224, a second extension 1226 protruding from the rotating arm 1223 towards the first extension 1224, a third elastic beam 1227 connected to the end of the rotating arm 1223 away from the first elastic beam 1221 and the side of one of the inside coupling units 13 away from the first elastic beam 1221, a bending portion 1228 formed by bending the end of the first extension 1224 away from the second elastic beam 1222 around the other inside coupling unit 13, a fourth elastic beam 1229 connected to the end of the bending portion 1228 away from the first extension 1224 and the side of the corresponding inside coupling unit 13 away from the second elastic beam 1222, and a fifth elastic beam 12210 connected to the bending portion 1228, the second extension 1226 is spaced apart from the bending portion 1228 and the fixed portion 1225 respectively, and the fifth elastic beam 12210 is located between and spaced apart from the two anchor points 2; the ends of the two torsion springs 121 in each seesaw structure 12 away from each other are connected to the corresponding rotating arm 1223 and first extension 1224 respectively, and are spaced apart from the fixed portion 1225, the second extension 1226, and the bending portion 1228 respectively, the ends of the two torsion springs 121 in the seesaw structure 12 close to each other are fixed to the corresponding anchor points 2 respectively, and the fifth elastic beam 12210 in each seesaw structure 12 is connected to the fifth elastic beam 12210 in the other seesaw structure 12.

[0041] The end of each anchor point 2 away from the other anchor point 2 is connected to the corresponding two torsion springs 121 through an extension arm 21, the extension arm 21 is located between and spaced apart from the corresponding second extension 1226 and bending portion 1228 respectively.

[0042] The seesaw structure 12 in the embodiment is arranged in a nested manner, i.e., arranged in an inserted manner between the outer coupling unit 11 and the inner coupling unit 13, so as to suppress the remaining translation and rotation modes of the seesaw, thereby preventing the influence of angular velocity.

[0043] Both of the two anchor points 2 in the embodiment are located in the middle region of the outer coupling unit 11, so that the stress influence in the processing process is small, and the process error is also small.

[0044] The accelerometer 100 further comprises out-of-plane detection devices arranged in the regions of the base 4 opposite to the outer coupling unit 11 and the inner coupling unit 13, respectively. The out-of-plane detection devices are used to detect the linear motion of the outer coupling unit 11 and / or the inner coupling unit 13 in the first direction by using a capacitive detection manner.

[0045] In the embodiment, the base 4 comprises a base plate 41 and a cover 42 fixed to the base plate 41 and together enclosing a receiving space 40, and the sensing unit 1 is arranged in the receiving space 40. The out-of-plane detection devices comprise first capacitive plates 5 fixed to the regions of the base plate 41 or the cover 42 opposite to the outer coupling unit 11 and second capacitive plates 6 fixed to the regions of the base plate 41 or the cover 42 opposite to the inner coupling unit 13.

[0046] The number of the first capacitive plates 5 is the same as the number of the outer coupling units 11, and the number of the second capacitive plates 6 is the same as the number of the inner coupling units 13.

[0047] The detection modes of each axis of the accelerometer 100 in the embodiment are shown in FIG. 4, wherein a is the X-axis detection mode, b is the Y-axis detection mode, and c is the Z-axis detection mode. The modular cross section of the accelerometer 100 in the embodiment is shown in FIG. 5, wherein d is the X-axis cross section, which shows that the first capacitive plates 5 are arranged in the regions of the base plate 41 opposite to the outer coupling units 11, and f is the Y-axis cross section, which shows that the second capacitive plates 6 are arranged in the regions of the cover 42 opposite to the inner coupling units 13.

[0048] Compared with the related art, the overall structure of the accelerometer 100 in the embodiment is supported by two opposite seesaw structures 12, and the outer coupling structure is coupled to the outer side of the two seesaw structures 12, and the inner coupling structure is coupled to the inner side of the seesaw structure 12, and the two seesaw structures 12 are arranged in a central symmetry, and the two inner coupling units 13 are symmetrically arranged about the connecting line of the two anchor points 2 and are located on opposite sides of the anchor points 2, so that the rotation of the seesaw structure 12 in the plane about the axis (Z axis) perpendicular to the plane is suppressed to a certain extent, the cross coupling of the seesaw structure 12 is reduced, and the proof masses of the accelerometer 100 are distributed on the outer coupling unit 11 and / or the inner coupling unit 13. When the out-of-plane acceleration perpendicular to the plane axis arrives, the outer coupling unit 11 and the inner coupling unit 13 on both sides of the seesaw structure 12 move differentially relative to the base 4, causing the detection capacitance in the out-of-plane detection device to form a parallel plate capacitor with the sensing unit 1 and change differentially. In other words, when subjected to the out-of-plane acceleration, the mass of the outer coupling unit 11 will move in the direction of the acceleration due to its larger mass, and the mass of the inner coupling unit 13 will move in the opposite direction of the acceleration due to its smaller mass. Thus, the capacitance corresponding to the outer coupling unit 11 will increase, and the capacitance corresponding to the inner coupling unit 13 will decrease, thereby forming a differential capacitance, and the acceleration perpendicular to the plane axis can be detected by detecting the change in the detection capacitance. This structure makes the displacement of the out-of-plane detection capacitance all linear displacement, greatly improving the linearity of the acceleration detection.

[0049] Embodiment Two

[0050] In combination with FIG. 6, the accelerometer 100 in the embodiment not only includes various structures of the embodiment one, but also includes an in-plane detection device 3. The in-plane detection device 3 is arranged on the outer coupling unit 11, and the in-plane detection device 3 is used to detect the linear motion of the outer coupling unit 11 in the second direction and / or the linear motion of the outer coupling unit 11 in the third direction by using the capacitive detection method. The first direction, the second direction and the third direction are perpendicular to each other.

[0051] Specifically, the in-plane detection device 3 includes a plurality of X-axis in-plane detection units 31 for detecting the linear motion of the outer coupling unit 11 in the second direction and / or a plurality of Y-axis in-plane detection units 32 for detecting the linear motion of the outer coupling unit 11 in the third direction. The in-plane detection device 3 in the embodiment includes the plurality of X-axis in-plane detection units 31 and the plurality of Y-axis in-plane detection units 32.

[0052] The X-axis in-plane detection units 31 and the Y-axis in-plane detection units 32 in the embodiment are the same as or similar to the out-of-plane detection device in the embodiment one, and will not be repeated here.

[0053] The accelerometer 100 in the embodiment can directly detect acceleration in three mutually perpendicular directions of the accelerometer 100 by adding the X-axis in-plane detection unit 31 and the Y-axis in-plane detection unit 32, that is, a three-axis capacitive acceleration sensor is formed.

[0054] The above merely describes the embodiments of the present application, and it should be pointed out that those skilled in the art can make improvements without departing from the concept of the present application, and these improvements are within the protection scope of the present application.

Claims

1. An accelerometer comprising a base, a sensing unit arranged on the base, and two anchor points fixed to the base and located at the same level as the sensing unit, the two anchor points being arranged in a facing and spaced manner; characterized in that, The sensing unit comprises: An outer coupling unit stacked on the base; A seesaw structure comprising two seesaw structures symmetrically arranged at the inner side of the outer coupling unit; An inner coupling unit comprising two inner coupling units symmetrically arranged about the connecting line of the two anchor points and located on opposite sides of the anchor points; each seesaw structure is elastically connected to the outer coupling unit, the two inner coupling units, and the other seesaw structure; A test mass fixed to the outer coupling unit and / or the inner coupling unit; The accelerometer further comprises an out-of-plane detection device arranged in the base area opposite to the outer coupling unit and the base area opposite to the inner coupling unit, which detects the linear motion of the outer coupling unit and / or the inner coupling unit in the first direction by capacitive detection.

2. The accelerometer of claim 1, wherein The seesaw structure is arranged in a nested manner.

3. The accelerometer of claim 1, wherein Both anchor points are located in the middle region of the outer coupling unit.

4. The accelerometer of claim 1, wherein The outer coupling unit comprises a rectangular ring-shaped support portion, two counterweight portions spaced apart from each other, and two connecting portions respectively connecting the two counterweight portions to the opposite sides of the support portion, the counterweight portions are spaced apart from the support portion and the seesaw structure; the counterweight portion also serves as a test mass.

5. The accelerometer of claim 4, wherein, Each seesaw structure comprises two torsion springs spaced apart from each other and an elastic member fixed to the two torsion springs, one end of each torsion spring is fixed to the corresponding anchor point, and the other end of each torsion spring is connected to the elastic member; the elastic member in each seesaw structure is elastically connected to the elastic member in the outer coupling unit, the two inner coupling units, and the other seesaw structure, and the elastic member in each seesaw structure is spaced apart from the elastic member in the outer coupling unit, the two inner coupling units, and the other seesaw structure.

6. The accelerometer of claim 5, wherein, The elastic member in each of the seesaw structures comprises a first elastic beam and a second elastic beam fixed on opposite sides of the connecting portion, a rotating arm fixed on an end of the first elastic beam away from the connecting portion, a first extension fixed on an end of the second elastic beam away from the connecting portion, a fixed portion extending from the rotating arm to the first extension, a second extension extending from the rotating arm towards the first extension, a third elastic beam connected to an end of the rotating arm away from the first elastic beam and an end of one of the inner coupling units away from the first elastic beam, a bending portion formed by bending an end of the first extension away from the second elastic beam around the other inner coupling unit, a fourth elastic beam connected to an end of the bending portion away from the first extension and an end of the corresponding inner coupling unit away from the second elastic beam, and a fifth elastic beam connected to the bending portion, the second extension is arranged between the fixed portion and the bending portion, and the fifth elastic beam is arranged between the two anchor points.

7. The accelerometer of claim 6, wherein An end of each of the anchor points away from the other anchor point is connected to two corresponding torsion springs through an extension arm, the extension arm is arranged between the corresponding second extension and the bending portion.

8. The accelerometer of claim 1, wherein The base comprises a base and a cover fixed to the base and collectively forming a receiving space, and the sensing unit is arranged in the receiving space; the out-of-plane detection device comprises a first capacitor plate fixed to a region of the base opposite to the outer coupling unit or a region of the cover, and a second capacitor plate fixed to a region of the base opposite to the inner coupling unit.

9. The accelerometer of claim 1, wherein The accelerometer further comprises an in-plane detection device arranged on the outer coupling unit, the in-plane detection device is used to detect linear motion of the outer coupling unit in a second direction by capacitive detection, and / or is used to detect linear motion of the outer coupling unit in a third direction; the first direction, the second direction and the third direction are perpendicular to each other.

10. The accelerometer of claim 9, wherein, The in-plane detection device comprises a plurality of X-axis in-plane detection units for detecting linear motion of the outer coupling unit in the second direction, and / or a plurality of Y-axis in-plane detection units for detecting linear motion of the outer coupling unit in the third direction.

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