An accelerometer

Abstract

The application provides an accelerometer, which comprises a substrate and a detection structure connected to the substrate, the detection structure comprising an anchor point fixed to the substrate, seesaw structures elastically connected to the anchor point, an inner side coupling structure coupled to the inner side of the seesaw structures, an outer side coupling structure coupled to the outer side of the seesaw structures, and a displacement detection assembly arranged on the outer side coupling structure and the inner side coupling structure, the two seesaw structures being oppositely arranged; the outer side coupling structure comprises an inner ring of the outer side coupling structure coupled to the outer side of the two seesaw structures and an outer ring of the outer side coupling structure surrounding the outer side of the inner ring of the outer side coupling structure; the detection structure further comprises a first elastic member connecting the inner ring of the outer side coupling structure and the seesaw structures and a second elastic member connecting the inner ring of the outer side coupling structure and the outer ring of the outer side coupling structure. The application improves the stiffness of the rotation mode of the outer side coupling structure, improves the resonance frequency corresponding to the rotation mode, and reduces the cross coupling of the accelerometer.

Description

TECHNICAL FIELD

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

[0002] The Z-axis out-of-plane acceleration detection and Y-axis in-plane acceleration detection of the accelerometer in the related art share an asymmetric rotating proof mass, and the X-axis in-plane acceleration detection takes the whole seesaw structure as a linear proof mass, and the three axes are detected through corresponding capacitor plates. However, the acceleration detection of the Y-axis and the Z-axis will be affected by the angular acceleration around the Z-axis and the X-axis respectively, so that the proof mass is offset under the action of the corresponding angular acceleration, resulting in high cross-coupling of the detection of each axis. SUMMARY

[0003] The purpose of the present application is to provide a low cross-coupling three-axis accelerometer to solve the problem of high cross-coupling of the detection of each axis in the related art under the action of the corresponding angular acceleration.

[0004] The present application provides an accelerometer, which comprises a substrate and a detection structure connected to the substrate, wherein the detection structure comprises anchor points fixed on the substrate, seesaw structures elastically connected to the anchor points, inner side coupling structures coupled to the inner side of the seesaw structures, outer side coupling structures coupled to the outer side of the seesaw structures, and displacement detection components arranged on the outer side coupling structures and the inner side coupling structures.

[0005] The two seesaw structures are arranged oppositely.

[0006] The outer side coupling structure comprises an inner ring of the outer side coupling structure coupled to the outer side of the two seesaw structures and an outer ring of the outer side coupling structure arranged outside the inner ring of the outer side coupling structure.

[0007] The detection structure further comprises first elastic members connecting the inner ring of the outer side coupling structure and the corresponding seesaw structure, and second elastic members connecting the inner ring of the outer side coupling structure and the outer ring of the outer side coupling structure.

[0008] Further, the detection structure further comprises third elastic members connecting the anchor points and the corresponding seesaw structures.

[0009] The two sides of the same seesaw structure are connected to the corresponding anchor points through the corresponding third elastic members.

[0010] Each anchor point is arranged between the opposite two ends of the corresponding seesaw structure.

[0011] Further, the second elastic member comprises a first elastic segment connected to the outer ring of the outer coupling structure and a second elastic segment connected to one end of the first elastic segment and to the inner ring of the outer coupling structure.

[0012] The first elastic segment and the second elastic segment are arranged in parallel.

[0013] Further, the inner coupling structure has a connecting beam connecting the two seesaw structures.

[0014] Further, the displacement detection assembly comprises an X-axis detection capacitor group and a Y-axis detection capacitor group arranged on the outer coupling structure.

[0015] The X-axis detection capacitor group is symmetrically distributed along the X-axis, and the X-axis detection capacitor group is symmetrically distributed along the Y-axis.

[0016] The Y-axis detection capacitor group is symmetrically distributed along the X-axis, and the Y-axis detection capacitor group is symmetrically distributed along the Y-axis.

[0017] Further, the X-axis detection capacitor group is arranged on both sides of the same seesaw structure, and the X-axis detection capacitor group is arranged between the first elastic member and the anchor point connecting the same seesaw structure.

[0018] The Y-axis detection capacitor group is arranged between two X-axis detection capacitor groups distributed along the length direction of the base.

[0019] Further, the Y-axis detection capacitor group is arranged on both sides of the same seesaw structure, and the Y-axis detection capacitor group is arranged between the first elastic member and the anchor point connecting the same seesaw structure.

[0020] The X-axis detection capacitor group is arranged between two Y-axis detection capacitor groups distributed along the length direction of the base.

[0021] Further, the X-axis detection capacitor group comprises a first capacitor plate arranged on the outer coupling structure, a second capacitor plate fixed to the base, and a third capacitor plate fixed to the base and arranged in a spaced manner with the second capacitor plate; wherein the first capacitor plate and the second capacitor plate, the third capacitor plate are arranged in a differential manner.

[0022] The Y-axis detection capacitor group comprises a fourth capacitor plate arranged on the outer coupling structure, a fifth capacitor plate fixed to the base, and a sixth capacitor plate fixed to the base and arranged in a spaced manner with the fifth capacitor plate; wherein the fourth capacitor plate and the fifth capacitor plate, the sixth capacitor plate are arranged in a differential manner.

[0023] Further, the displacement detection assembly further comprises a Z-axis detection capacitor group arranged between the anchor points on the same side;

[0024] The two sides of the same seesaw structure are respectively provided with corresponding Z-axis detection capacitor groups.

[0025] Further, the Z-axis detection capacitor group comprises a seventh capacitor plate arranged on the inner coupling structure and the inner ring of the outer coupling structure, an eighth capacitor plate fixed on the substrate, and a ninth capacitor plate fixed on the substrate and spaced apart from the eighth capacitor plate; wherein the seventh capacitor plate and the eighth capacitor plate, the ninth capacitor plate are differentially arranged.

[0026] The beneficial effects of the present application are that the entire accelerometer is supported by two oppositely arranged seesaw structures, the inner coupling structure couples the inner sides of the two seesaw structures, and the outer coupling structure couples the outer sides of the two seesaw structures. When the out-of-plane Z-axis acceleration comes, the inner coupling structure and the outer coupling structure on both sides of the seesaw structure make differential motion relative to the substrate, causing the displacement detection assembly arranged on the inner coupling structure and the outer coupling structure and the corresponding substrate to change differentially, so that the Z-axis acceleration can be detected by detecting the change of the displacement detection assembly. The inner ring of the outer coupling structure is connected to the corresponding seesaw structure through the first elastic member, so that the proof mass of the entire outer coupling structure has the ability to move under the action of X-axis acceleration, and the outer ring of the outer coupling structure is connected to the inner ring of the outer coupling structure through the second elastic member, so that the proof mass of the outer ring of the outer coupling structure has the ability to move under the action of Y-axis acceleration. The elastic connection design of the inner and outer rings to divide the in-plane XY-axis makes the rotational modal stiffness of the proof mass of the outer coupling structure improve, improves the cross-coupling ratio, and reduces the cross-coupling. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A perspective view of the detection structure provided by the present application is provided;

[0028] Figure 2 A plan view of the detection structure provided by the first embodiment of the present application is provided;

[0029] Figure 3 An X-axis detection modal diagram of the accelerometer provided by the first embodiment of the present application is provided;

[0030] Figure 4 A Y-axis detection modal diagram of the accelerometer provided by the first embodiment of the present application is provided;

[0031] Figure 5 A Z-axis detection modal diagram of the accelerometer provided by the first embodiment of the present application is provided;

[0032] Figure 6 This is a schematic diagram of the rotational modes of the accelerometer provided in Embodiment 1 of the present invention;

[0033] Figure 7 This is a plan view of the accelerometer provided in Embodiment 2 of the present invention.

Detailed Implementation Methods

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] Please see Figures 1 to 6 This invention provides an accelerometer, including a base and a detection structure 1 connected to the base. The detection structure 1 includes an anchor point 11 fixed to the base, a seesaw structure 12 elastically connected to the anchor point 11, an inner coupling structure 13 coupled to the inner side of the seesaw structure 12, an outer coupling structure 14 coupled to the outer side of the seesaw structure 12, and a displacement detection component 15 disposed on the outer coupling structure 14 and the inner coupling structure 13. The two seesaw structures 12 are disposed opposite to each other. The outer coupling structure 14 includes an inner ring 141 coupled to the outer side of the two seesaw structures 12 and an outer ring 142 surrounding the outer ring 141. The detection structure 1 also includes a first elastic element 16 connecting the inner ring 141 of the outer coupling structure to the corresponding seesaw structure 12 and a second elastic element 17 connecting the inner ring 141 of the outer coupling structure to the outer ring 142 of the outer coupling structure.

[0036] In this embodiment, the entire accelerometer is supported by two opposing seesaw structures 12. An inner coupling structure 13 couples the inner sides of the two seesaw structures 12, and an outer coupling structure 14 couples the outer sides of the two seesaw structures 12. The test mass of the accelerometer is distributed on the inner coupling structure 13 and the outer coupling structure 14, but is mainly concentrated on the outer coupling structure 14. When out-of-plane Z-axis acceleration occurs, the inner coupling structure 13 and the outer coupling structure 14 on both sides of the seesaw structure 12 undergo differential motion relative to the base, causing differential changes in the displacement detection components 15 disposed on the inner coupling structure 13 and the outer coupling structure 14 and the corresponding base. Therefore, the Z-axis acceleration can be detected by detecting the changes in the displacement detection components 15. The inner ring 141 of the outer coupling structure is connected to the corresponding seesaw structure 12 through the first elastic element 16, enabling the inspection mass block of the entire outer coupling structure 14 to move under the action of X-axis acceleration. The outer ring 142 of the outer coupling structure is connected to the inner ring 141 of the outer coupling structure through the second elastic element 17, enabling the inspection mass block of the outer ring 142 of the outer coupling structure to move under the action of Y-axis acceleration. This elastic connection design of the XY axis in the inner and outer ring split plane improves the rotational modal stiffness of the inspection mass of the outer coupling structure 14, increases the cross suppression ratio, and reduces cross coupling.

[0037] In this embodiment, the first elastic member 16 is an X-axis single-degree-of-freedom spring, the third elastic member 18 is a torsion spring, and the accelerometer is a symmetrical structure, i.e., the accelerometer is symmetrical on both sides of the center line 2, the two seesaw structures 12 are respectively located on both sides of the center line 2, one end of the seesaw structure 12 close to the center line 2 is connected with the inner coupling structure 13, and the other end of the seesaw structure 12 away from the center line 2 is connected with the X-axis single-degree-of-freedom spring. Specifically, the detection structure 1 further includes a torsion spring connecting the anchor point 11 and the corresponding seesaw structure 12, and the same seesaw structure 12 is connected with the corresponding anchor point 11 through the corresponding torsion spring on both sides (i.e., four torsion springs and four anchor points 11 are provided in this embodiment, and each seesaw structure 12 is elastically connected with two anchor points 11 through the corresponding torsion spring); each anchor point 11 is arranged between the opposite two ends of the corresponding seesaw structure 12, so that the two seesaw structures 12 rotate around the respective rotation axes (i.e., the rotation axis composed of the third elastic member 18 and the anchor point 11 on both sides of the same seesaw structure 12) and are symmetrical with respect to the center line 2, which to some extent suppresses the rotation of the seesaw structure 12 around the Z axis in the plane and reduces the cross coupling of the structure.

[0038] It should be noted that the proof mass is mainly distributed on the outer coupling structure 14, and since the anchor point 11 is fixed to the base, when the seesaw structure 12 moves linearly along the X axis, the seesaw structure 12 utilizes the elastic properties of the X-axis single-degree-of-freedom spring and the torsion spring to make the proof mass have a linear motion mode in the in-plane direction (X-axis direction / Y-axis direction) perpendicular to the base plane, a linear motion mode parallel to the base plane, and a rotation mode. The motion directions of the proof mass in the several modes are perpendicular to each other, so that the proof mass moves linearly in the in-plane direction (X-axis direction / Y-axis direction) perpendicular to the base plane under the action of in-plane acceleration and moves linearly in the out-of-plane direction (Z-axis direction) parallel to the base plane under the action of out-of-plane acceleration. It should be noted that in other embodiments, the third elastic member 18 can also be a tension spring or other type of elastic structure, which is not particularly limited here as long as it can satisfy the elastic connection between the seesaw structure 12 and the anchor point 11.

[0039] In this embodiment, the inner coupling structure 13 has a connecting beam 131 connecting the two seesaw structures 12, so that the inner coupling structure 13 has stronger constraint on the seesaw structure 12, the stiffness of the rotation parasitic mode of the outer coupling structure 14 is improved, the cross suppression ratio of the structure is increased, and the cross coupling of the accelerometer is reduced.

[0040] In the embodiment, the second elastic member 17 includes a first elastic segment 171 connected with the outer coupling structure outer ring 142, and a second elastic segment 172 having one end connected with the first elastic segment 171 and the other end connected with the outer coupling structure inner ring 141, and the first elastic segment 171 and the second elastic segment 172 are arranged in parallel.

[0041] Taking the second elastic member 17 as an example of the Y-axis single-degree-of-freedom spring, since the Y-axis single-degree-of-freedom spring has a bent part (i.e., the connection part of the first elastic segment 171 and the second elastic segment 172), the Y-axis single-degree-of-freedom spring has better elastic force; and the Y-axis single-degree-of-freedom spring cooperates with the outer coupling structure inner ring 141 and the outer coupling structure outer ring 142, so that when the proof mass moves linearly in the in-plane direction (X-axis direction / Y-axis direction) perpendicular to the base plane under the action of in-plane acceleration or moves linearly in the out-of-plane direction (Z-axis direction) parallel to the base plane under the action of out-of-plane acceleration, the stiffness of the rotational mode of the outer coupling structure 14 can be improved, the resonance frequency corresponding to the rotational mode can be improved, and the cross coupling of the accelerometer can be reduced.

[0042] In the embodiment, the displacement detection assembly 15 includes an X-axis detection capacitor group 151 and a Y-axis detection capacitor group 152 arranged on the outer coupling structure 14; the X-axis detection capacitor group 151 is symmetrically distributed along the X-axis, and the X-axis detection capacitor group 151 is symmetrically distributed along the Y-axis; the Y-axis detection capacitor group 152 is symmetrically distributed along the X-axis, and the Y-axis detection capacitor group 152 is symmetrically distributed along the Y-axis.

[0043] The X-axis detection capacitor group 151 is arranged between the first elastic member 16 and the anchor point 11 connected to the same seesaw structure 12. Specifically, the first elastic member 16 and the anchor point 11 connected to the same seesaw structure 12 enclose a first area 19, and the first area 19 in the embodiment is exemplified by four first areas 19, and the two first areas 19 on the two sides of the seesaw structure 12 are oppositely arranged, and the two first areas 19 beside different seesaw structures 12 are symmetrically arranged about the center line 2, and the X-axis detection capacitor group 151 is arranged in the corresponding first area 19, and at this time, the X-axis detection capacitor group 151 is located in the corresponding area on the corresponding base of the outer coupling structure 14 and the first area 19; in the embodiment, the first area 19 is enclosed by the second elastic member 17 and the outer coupling structure inner ring 141.

[0044] It should be noted that the embodiment can detect the X-axis acceleration by setting the X-axis detection capacitor group 151 on the outer coupling structure 14. It should be pointed out here that the X-axis detection capacitor group 151 can be arranged on the outer coupling structure outer ring 142 or the outer coupling structure inner ring 141, and does not change the detection capability of the X-axis acceleration. Each first area 19 has multiple X-axis detection capacitor groups 151, which are arranged in sequence along the direction of the X-axis. Of course, the multiple X-axis detection capacitor groups 151 of each first area 19 can also be arranged in multiple rows, and each row has the same number of X-axis detection capacitor groups 151 arranged in sequence along the direction of the X-axis.

[0045] The Y-axis detection capacitor group 152 is arranged between the two X-axis detection capacitor groups 151 distributed along the length direction of the base. The Y-axis detection capacitor group 152 is distributed on both sides of the X-axis as the axis. It should be noted that the embodiment can detect the Y-axis acceleration by setting the Y-axis capacitor plate on the outer ring 142 of the outer coupling structure. Each side has multiple Y-axis detection capacitor groups 152, which are arranged in sequence along the direction of the X-axis. Of course, the multiple Y-axis detection capacitor groups 152 on each side can also be arranged in multiple rows, and each row has the same number of Y-axis detection capacitor groups 152 arranged in sequence along the direction of the X-axis.

[0046] As shown in Figure 7 In some embodiments, the Y-axis detection capacitor group 152 can also be arranged on both sides of the same seesaw structure 12, and the Y-axis detection capacitor group 152 is arranged between the first elastic member 16 and the anchor point 11 connected to the same seesaw structure 12; The X-axis detection capacitor group 151 is arranged between the two Y-axis detection capacitor groups 152 distributed along the length direction of the base.

[0047] In the embodiment, the X-axis detection capacitor group 151 includes a first capacitor plate 1511 arranged on the outer coupling structure 14, a second capacitor plate 1512 fixed on the base, and a third capacitor plate 1513 fixed on the base and spaced apart from the second capacitor plate 1512; Wherein, the second capacitor plate 1512 and the third capacitor plate 1513 are arranged in parallel. Because the second capacitor plate 1512 and the third capacitor plate 1513 are arranged in parallel, by fixing the moving capacitor plate (i.e. the first capacitor plate 1511) on the proof mass (i.e. the outer coupling structure outer ring 142), the fixed capacitor plate (i.e. the second capacitor plate 1512 and the third capacitor plate 1513) can be directly fixed on the base or fixed on the base through the electrode anchor point 154 (as Figure 7As shown in the figure, when the test mass moves linearly in the in-plane direction (i.e., the X-axis direction) perpendicular to the base plane under the action of in-plane acceleration, the acceleration of the X-axis can be detected. It should be noted that the first capacitive plate 1511 is differentially arranged with the second capacitive plate 1512 and the third capacitive plate 1513.

[0048] The Y-axis detection capacitive group 152 includes a fourth capacitive plate 1521 arranged on the outer coupling structure 14, a fifth capacitive plate 1522 fixed on the base, and a sixth capacitive plate 1523 fixed on the base and spaced apart from the fifth capacitive plate 1522; wherein the fifth capacitive plate 1522 and the sixth capacitive plate 1523 are arranged in parallel. Since the fifth capacitive plate 1522 and the sixth capacitive plate 1523 are spaced apart, and by fixing the moving capacitive plate (i.e., the fourth capacitive plate 1521) on the test mass (i.e., the outer ring 142 of the outer coupling structure), the fixed capacitive plate (i.e., the fifth capacitive plate 1522 and the sixth capacitive plate 1523) is directly fixed on the base or fixed on the base through the electrode anchor point 154 (as shown in the figure). Figure 7 As shown in the figure, when the test mass moves linearly in the in-plane direction (i.e., the Y-axis direction) perpendicular to the base plane under the action of in-plane acceleration, the acceleration of the Y-axis can be detected.

[0049] It should be noted that the fourth capacitive plate 1521 is differentially arranged with the fifth capacitive plate 1522 and the sixth capacitive plate 1523; the extension line between the second capacitive plate 1512 and the fifth capacitive plate 1522 is arranged perpendicularly, that is, the arrangement direction of the second capacitive plate 1512 is perpendicular to the arrangement direction of the fifth capacitive plate 1522, which respectively satisfies the detection of the X-axis acceleration and the detection of the Y-axis acceleration.

[0050] In this embodiment, the displacement detection assembly 15 further includes a Z-axis detection capacitive group 153 arranged between the anchor points 11 on the same side, wherein the two sides of the same seesaw structure 12 are respectively provided with a corresponding Z-axis detection capacitive group 153. Specifically, in this embodiment, the Z-axis detection capacitive group 153 takes 8 as an example, and is symmetrically arranged with the X-axis as the center line, that is, there are 4 Z-axis detection capacitive groups 153 on each side, which are sequentially arranged on the inner ring 141 of the outer coupling structure, the inner coupling structure 13 and the inner ring 141 of the outer coupling structure. That is, the same side of the same seesaw structure 12 has two Z-axis detection capacitive groups 153, one of which is located on the inner ring 141 of the outer coupling structure, and the other of which is located on the inner coupling structure 13.

[0051] In the embodiment, the Z-axis detection capacitor group 153 includes a seventh capacitor plate (not shown in the figure) arranged on the inner coupling structure 13 and the outer coupling structure inner ring 141, an eighth capacitor plate (not shown in the figure) fixed on the base, and a ninth capacitor plate (not shown in the figure) fixed on the base and spaced apart from the eighth capacitor plate. The Z-axis detection capacitor group 153 arranged on the inner coupling structure 13 and the outer coupling structure inner ring 141 has higher Z-axis detection linearity than arranged on the outer coupling structure outer ring 142. Since the out-of-plane stiffness of the X-axis single-degree-of-freedom spring is much larger than the out-of-plane stiffness of the two-degree-of-freedom spring in the related art, the influence of the out-of-plane stiffness of the Y-axis single-degree-of-freedom spring on the Z-axis detection is weakened, so that the Z-axis detection linearity is not affected by the out-of-plane stiffness of the Y-axis single-degree-of-freedom spring, and the Z-axis detection linearity is improved. When the proof mass moves linearly parallel to the base plane, the acceleration of the Z-axis can be detected. Wherein, the surrounding area 1531 as shown in the figure is the corresponding out-of-plane Z-axis acceleration capacitor plate (i.e. the eighth capacitor plate and the ninth capacitor plate) on the corresponding base or CAP (cavity cover), and it should be noted that the eighth capacitor plate and the ninth capacitor plate are directly fixed on the base. Of course, the capacitor plates (i.e. the seventh capacitor plate, the eighth capacitor plate, and the ninth capacitor plate) in the Z-axis detection capacitor group 153 can also be differentially arranged. Figure 2

[0052] The above only describes the embodiments of the present application, and it should be noted that those skilled in the art can make improvements without departing from the inventive concept, and these improvements are within the protection scope of the present application.​

Claims

1. A kind of accelerometer, comprising substrate and detection structure connected to the substrate, the detection structure includes anchor point fixed on the substrate, seesaw structure elastically connected with the anchor point, inner side coupling structure coupled with the inside of the seesaw structure, outer side coupling structure coupled with the outside of the seesaw structure and displacement detection component arranged on the outer side coupling structure, the inner side coupling structure, it is characterized in that, two the seesaw structure is oppositely arranged; The outer side coupling structure includes outer side coupling structure inner ring coupled with the outside of two the seesaw structure and outer side coupling structure outer ring surrounded outside the outer side coupling structure inner ring; The detection structure further includes first elastic member connecting the outer side coupling structure inner ring with corresponding the seesaw structure and second elastic member connecting the outer side coupling structure inner ring with the outer side coupling structure outer ring, the first elastic member is X-axis single degree of freedom spring, and the second elastic member is Y-axis single degree of freedom spring; The displacement detection component further includes Z-axis detection capacitor group arranged between the anchor point of the same side, and the Z-axis detection capacitor group is arranged on the inner side coupling structure and the outer side coupling structure inner ring; The detection structure further includes third elastic member connecting the anchor point with corresponding the seesaw structure; Two sides of the same the seesaw structure are connected with corresponding the anchor point through corresponding the third elastic member; Each the anchor point is arranged between the opposite two ends of corresponding the seesaw structure; The second elastic member includes first elastic section connected with the outer side coupling structure outer ring and second elastic section with one end connected with the first elastic section and the other end connected with the outer side coupling structure inner ring; The first elastic section and the second elastic section are arranged in parallel; The inner side coupling structure has connecting beam connecting two the seesaw structure; The displacement detection component includes X-axis detection capacitor group and Y-axis detection capacitor group arranged on the outer side coupling structure; The X-axis detection capacitor group is symmetrically distributed along the X-axis, and the X-axis detection capacitor group is symmetrically distributed along the Y-axis; The Y-axis detection capacitor group is symmetrically distributed along the X-axis, and the Y-axis detection capacitor group is symmetrically distributed along the Y-axis; The X-axis detection capacitor group is arranged on two sides of the same the seesaw structure, and the X-axis detection capacitor group is arranged between the first elastic member and the anchor point connecting the same the seesaw structure; The Y-axis detection capacitor group is arranged between two the X-axis detection capacitor group distributed along the length direction of the substrate; The Y-axis detection capacitor group is arranged on two sides of the same the seesaw structure, and the Y-axis detection capacitor group is arranged between the first elastic member and the anchor point connecting the same the seesaw structure; The X-axis detection capacitor group is arranged between two the Y-axis detection capacitor group distributed along the length direction of the substrate. ​ ​ ​ ​ 2. The accelerometer of claim 1, wherein: ​ ​ ​ 3. The accelerometer of claim 1, wherein: ​ ​ 4. The accelerometer of claim 1, wherein: ​ 5. The accelerometer of claim 1, wherein: ​ ​ ​ 6. The accelerometer of claim 5, wherein: ​ ​ 7. The accelerometer of claim 5, wherein: ​ ​ 8. An accelerometer as claimed in either of claims 6 or 7, characterised in that: The X-axis detection capacitor group comprises a first capacitor plate arranged on the outer coupling structure, a second capacitor plate fixed on the substrate, and a third capacitor plate fixed on the substrate and spaced apart from the second capacitor plate; wherein the first capacitor plate is differentially arranged with the second capacitor plate and the third capacitor plate; The Y-axis detection capacitor group comprises a fourth capacitor plate arranged on the outer coupling structure, a fifth capacitor plate fixed on the substrate, and a sixth capacitor plate fixed on the substrate and spaced apart from the fifth capacitor plate; wherein the fourth capacitor plate is differentially arranged with the fifth capacitor plate and the sixth capacitor plate.

9. The accelerometer of claim 1, wherein: Both sides of the same seesaw structure are respectively provided with corresponding Z-axis detection capacitor groups.

10. The accelerometer of claim 9, wherein: The Z-axis detection capacitor group comprises a seventh capacitor plate arranged on the inner coupling structure and the inner ring of the outer coupling structure, an eighth capacitor plate fixed on the substrate, and a ninth capacitor plate fixed on the substrate and spaced apart from the eighth capacitor plate; wherein the seventh capacitor plate is differentially arranged with the eighth capacitor plate and the ninth capacitor plate.

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