CN211206555U

CN211206555U - Three-axis accelerometer

Info

Publication number: CN211206555U
Application number: CN201921860039.5U
Authority: CN
Inventors: 蒋乐跃; 赵阳
Original assignee: Memsic Semiconductor Wuxi Co Ltd
Current assignee: Meixin semiconductor (Tianjin) Co.,Ltd.
Priority date: 2019-10-31
Filing date: 2019-10-31
Publication date: 2020-08-07
Anticipated expiration: 2029-10-31

Abstract

The utility model discloses a triaxial accelerometer, it includes: a substrate; an anchor block fixedly arranged on the substrate; a first X-axis electrode, a second X-axis electrode, a first Y-axis electrode, a second Y-axis electrode, a first Z-axis electrode and a second Z-axis electrode which are fixedly arranged on the substrate; a frame suspended above the substrate and including a first beam column and a second beam column disposed opposite to each other, the first beam column forming a third Z-axis electrode, the second beam column forming a fourth Z-axis electrode; a mass suspended above the substrate, the mass having a third X-axis electrode and a third Y-axis electrode formed thereon; and the elastic connecting component is configured to be elastically connected to the anchor block, the connecting beam and the mass block. The utility model discloses a triaxial accelerometer only needs a quality piece, just can realize the high accuracy acceleration detection of three axle, especially can provide the fully differential detected signal to the Z axle, great improvement detect the precision.

Description

Three-axis accelerometer

[ technical field ] A method for producing a semiconductor device

The utility model relates to a MEMS (Micro-Electro-Mechanical System) field especially relates to a triaxial accelerometer.

[ background of the invention ]

The MEMS accelerometer is generally used as a motion sensor, and compared with a conventional accelerometer, the MEMS accelerometer has the advantages of small size, light weight, low power consumption, low cost, good reliability, easy integration, strong overload capability, and mass production, and is one of the main development directions of accelerometers, and can be widely applied to the fields of aerospace, automobile industry, industrial automation, robots, and the like.

The common MEMS accelerometer has a working principle based on newton's classical mechanics, and generally comprises a sensing mass, a fixed support and a detection circuit. The mass block is attached to the fixed support by one or more elastic elements, when external acceleration is input, the sensitive mass block is displaced under the action of inertia force, the change size and direction of the displacement and the size and direction of the input acceleration have a determined corresponding relation, and the displacement can cause some related physical quantities (capacitance, pressure, resistance, resonant frequency and the like) to be correspondingly changed, so if the change of the physical quantities can be converted into easily-measured electrical quantities such as voltage, current, frequency and the like through the detection circuit, the displacement change condition of the mass block can be measured, and the information of the acceleration to be measured can be indirectly acquired. In addition, according to the measured acceleration, the speed of the sensitive mass block can be obtained through primary integral operation, and the movement distance of the sensitive mass block can be obtained through secondary integral operation.

However, it is common to measure the acceleration of two axes by using one mass, and even if the acceleration of three axes can be measured by using one mass, the detection accuracy of the Z axis is low.

Therefore, there is a need to provide a new and improved solution to overcome the above problems.

[ Utility model ] content

The to-be-solved technical problem of the utility model is to provide a triaxial accelerometer, it can provide the high accuracy acceleration detection of three axle.

In order to solve the above problem, according to the utility model discloses an aspect, the utility model provides a triaxial accelerometer, it includes: a substrate; an anchor block fixedly arranged on the substrate; a first X-axis electrode, a second X-axis electrode, a first Y-axis electrode, a second Y-axis electrode, a first Z-axis electrode and a second Z-axis electrode which are fixedly arranged on the substrate; a frame suspended above the substrate, the frame including a first beam column and a second beam column arranged opposite to each other, and a connection beam connecting the first beam column and the second beam column, the first beam column forming a third Z-axis electrode, the second beam column forming a fourth Z-axis electrode, wherein the first Z-axis electrode and the third Z-axis electrode are arranged opposite to each other to form a first Z-axis capacitor, and the second Z-axis electrode and the fourth Z-axis electrode are arranged opposite to each other to form a second Z-axis capacitor; a mass block suspended above the substrate, wherein a third X-axis electrode and a third Y-axis electrode are formed on the mass block, the first X-axis electrode and the third X-axis electrode are oppositely arranged to form a first X-axis capacitor, the second X-axis electrode and the third X-axis electrode are oppositely arranged to form a second X-axis capacitor, the first Y-axis electrode and the third Y-axis electrode are oppositely arranged to form a first Y-axis capacitor, and the second Y-axis electrode and the third Y-axis electrode are oppositely arranged to form a second Y-axis capacitor; and the elastic connecting component is configured to be elastically connected to the anchor block, the connecting beam and the mass block.

In a preferred embodiment, the frame, the proof mass, the spring coupling assembly, and the anchor block together form a proof mass electrode.

In a preferred embodiment, when acceleration is applied to the X-axis, the elastic connection component elastically deforms, the mass block moves along the X, a change in a gap between the first X-axis electrode and the third X-axis electrode causes a change in a first X-axis capacitance, a change in a gap between the second X-axis electrode and the third X-axis electrode causes a change in a second X-axis capacitance, the first X-axis capacitance and the second X-axis capacitance are opposite in change, the acceleration on the X-axis is detected by detecting a difference in a change in the first X-axis capacitance and the second X-axis capacitance, and when acceleration is applied to the Y-axis, the elastic connection component elastically deforms, the mass block moves along the Y, a change in a gap between the first Y-axis electrode and the third Y-axis electrode causes a change in a first Y-axis capacitance, and a change in a gap between the second Y-axis electrode and the third Y-axis electrode causes a change in a second Y-axis capacitance, through detecting the change of first Y axle electric capacity and second Y axle electric capacity is poor, and then detects and obtains the epaxial acceleration of Y, when having the acceleration on the Z axle, elastic connection subassembly elastic deformation, the quality piece moves along the Z axle, drives the frame rotates, and the clearance grow or diminish between first Z axle electrode and the third Z axle electrode leads to first Z axle electric capacity to diminish or grow, and the clearance between second Z axle electrode and the fourth Z axle electrode diminishes or grow and lead to second Z axle electric capacity grow or diminish, through detecting first Z axle electric capacity with the change of second Z axle electric capacity is poor, and then detects and obtain the epaxial acceleration of Z.

Compared with the prior art, the utility model discloses a triaxial accelerometer only needs a quality piece, just can realize the high accuracy acceleration detection of three axle, especially can provide the fully differential detected signal to the Z axle, great improvement detection accuracy.

With regard to other objects, features and advantages of the present invention, the following detailed description will be made in conjunction with the accompanying drawings.

[ description of the drawings ]

The present invention will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:

fig. 1 is a schematic top view of a three-axis accelerometer according to an embodiment of the present invention;

fig. 2 is a schematic cross-sectional view of a three-axis accelerometer of the present invention along the section line a-a in fig. 1;

FIG. 3 is an enlarged schematic view of a portion of the structure of the tri-axial accelerometer of FIG. 1;

FIG. 4 is a further enlarged schematic view of the tri-axial accelerometer of FIG. 3;

fig. 5 is a schematic structural diagram of a three-axis accelerometer according to the present invention at a predetermined time when acceleration is applied to the X-axis;

fig. 6 is a schematic structural diagram of a three-axis accelerometer according to the present invention at a predetermined time when acceleration is applied to the Y-axis;

fig. 7 is a schematic structural diagram of a three-axis accelerometer according to the present invention at a predetermined time when acceleration is applied to the Z-axis.

[ detailed description ] embodiments

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the detailed description.

Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. The term "a plurality" or "a plurality" in the present invention means two or more than two. In the present invention, "and/or" means "and" or ".

The utility model provides a triaxial accelerometer, this triaxial accelerometer can provide the high accuracy acceleration detection of three axle based on a quality piece.

Fig. 1 is a schematic top view of a three-axis accelerometer according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view of a three-axis accelerometer of the present invention along the section line a-a in fig. 1. Fig. 3 is an enlarged schematic view of a part of the structure of the triaxial accelerometer of fig. 1. Figure 4 is a further enlarged schematic view of the tri-axial accelerometer of figure 3.

As shown in fig. 1-2, the tri-axial accelerometer 100 comprises:

a substrate 10;

a first anchor block 1a and a second anchor block 1b fixedly provided on the substrate 10;

a first X-axis electrode 3a, a second X-axis electrode 3b, a first Y-axis electrode 4a, a second Y-axis electrode 4b, a first Z-axis electrode 6a, and a second Z-axis electrode 6b fixedly disposed on the substrate 10;

a frame 60 suspended above the substrate 10, including a first beam column 61 and a second beam column 62 disposed opposite to each other, and a first connection beam 63 and a second connection beam 64 connecting the first beam column and the second beam column, the first beam column 61 forming a third Z-axis electrode 5a, the second beam column 62 forming a fourth Z-axis electrode 5b, wherein the first Z-axis electrode 6a and the third Z-axis electrode 5a are disposed opposite to each other to form a first Z-axis capacitance, and the second Z-axis electrode 6b and the fourth Z-axis electrode 5b are disposed opposite to each other to form a second Z-axis capacitance;

a mass block 2 suspended above the substrate 10, wherein the frame 60 encloses a space, the mass block 2 is located in the frame 60, a third X-axis electrode 3c and a third Y-axis electrode 4c are formed on the mass block 2, wherein the first X-axis electrode 3a and the third X-axis electrode 3c are oppositely disposed to form a first X-axis capacitor, the second X-axis electrode 3b and the third X-axis electrode 3c are oppositely disposed to form a second X-axis capacitor, the first Y-axis electrode 4a and the third Y-axis electrode 4c are oppositely disposed to form a first Y-axis capacitor, and the second Y-axis electrode 4b and the third Y-axis electrode 4c are oppositely disposed to form a second Y-axis capacitor; and

a first elastic connecting member 71 and a second elastic connecting member 72, wherein the first elastic connecting member 71 is connected to the first anchor block 1a, the first connecting beam 63 and the mass block 2, and the second elastic connecting member 72 is connected to the second anchor block 1b, the second connecting beam 64 and the mass block 2.

In one embodiment, the frame 60, the mass 2, the

elastic connection members

71, 72 and the

anchor blocks

1b and 1a together form a mass electrode, i.e. the potentials of these components are all identical, and they constitute one and the same electrode. For example, the frame 60, the mass 2, the

elastic connection members

71 and 72, and the

anchor blocks

1b and 1a may be made of a conductive or semiconductive material or a composite material, and the potentials thereof are uniform. Thus, the proof-mass electrodes can provide uniform electric potentials to the third Z-axis electrode 5a, the fourth Z-axis electrode 5b, the third X-axis electrode 3c, and the third Y-axis electrode 4 c.

As shown in connection with fig. 1-4, each resilient connecting

member

71, 72 includes:

a connecting portion 81 (see fig. 4) connected to the

anchor blocks

1a and 1 b;

a first elastic portion 53 connected to one end of the connecting portion 81;

a second elastic part 66 connected to the other end of the connecting part 81;

a first elastic arm 51 connected to the first elastic portion 53;

a second elastic arm 57 connected to the second elastic portion 66;

a third elastic portion 54 connected between the first elastic arm 51 and the second elastic arm 57;

a fourth elastic portion 55 connected between the first elastic arm 51 and the middle portion of the connection beam, a portion of the first elastic arm 51 connected to the fourth elastic portion 55 and a portion of the connection beam connected to the fourth elastic portion 55 being spaced apart by a predetermined distance D in the X-axis direction (see fig. 4);

a fifth elastic portion 67 connected between the first elastic arm 51 and one side of the mass 2;

a sixth spring 68 connected between the second spring arm 57 and the other side of the mass 2.

As shown in fig. 1 and 3, the fifth elastic portion 67 includes a first elastic member 41 extending in the Y-axis direction and a second elastic member 42 extending in the X-axis direction, wherein the first elastic member 41 is connected to the mass 2, and the second elastic member 42 is connected to the first elastic arm 51. The sixth elastic portion 68 includes a first elastic member 43 extending in the Y-axis direction and a second elastic member 44 extending in the X-axis direction, wherein the first elastic member 43 is connected to the mass 2, and the second elastic member 44 is connected to the second elastic arm 57.

As shown in fig. 3 and 4, the connecting

beams

63 and 64 include a first end portion 52 connected to the first beam column 61, a second end portion 58 connected to the second beam column 62, and an intermediate portion between the first end portion 52 and the second end portion 58, the intermediate portion of the

connecting beams

63 and 64 includes a neck portion 56 (see fig. 4) on the inner side and a support portion 59 on the outer side, and one side of the support portion 59 is connected to the second end portion 58 and the other end is disconnected from the first end portion 52. The neck 56 and the support 59 have a gap between them, the neck 56 making the middle part of the connecting beam more elastic and the support 59 making the middle part stronger. The fourth elastic portion 55 is connected to the neck portion 56 at a midpoint position.

Fig. 5 is a schematic structural diagram of a three-axis accelerometer according to the present invention at a predetermined time when there is acceleration on the X-axis. When acceleration is applied to the X-axis, the

elastic connection members

71 and 72 elastically deform, the mass block 2 moves along the X, and the change of the gap between the X-axis electrodes causes a change of the X-axis capacitance, for example, the gap between the first X-axis electrode 3a and the third X-axis electrode 3c becomes larger, the first X-axis capacitance becomes smaller, the gap between the second X-axis electrode 3b and the third X-axis electrode 3c becomes smaller, the second X-axis capacitance becomes larger, and the gap between the first X-axis electrode 3a and the third X-axis electrode 3c becomes smaller, the first X-axis capacitance becomes larger, the gap between the second X-axis electrode 3b and the third X-axis electrode 3c becomes smaller, the second X-axis capacitance becomes smaller, and the acceleration on the X-axis can be obtained by detecting a difference of the changes of the first X-axis capacitance and the second X-axis capacitance. It should be noted that fig. 5 and subsequent fig. 6 and 7 are schematic illustrations of three-dimensional models of three-axis accelerometers, and the motion amplitude of the three-dimensional models is much larger than the actual motion amplitude for easy viewing.

Fig. 6 is a schematic structural diagram of a three-axis accelerometer according to the present invention at a predetermined time when acceleration is applied to the Y-axis. When acceleration is applied to the Y axis, the

elastic connection members

71 and 72 elastically deform, the mass block 2 moves along the Y axis, and the change of the gap between the Y axis electrodes causes a change of the Y axis capacitance, for example, the gap between the first Y axis electrode 4a and the third Y axis electrode 4c becomes larger, the first Y axis capacitance becomes smaller, the gap between the second Y axis electrode 4b and the third Y axis electrode 4c becomes smaller, the second Y axis capacitance becomes larger, and for example, the gap between the first Y axis electrode 4a and the third Y axis electrode 4c becomes smaller, the first Y axis capacitance becomes larger, the gap between the second Y axis electrode 4b and the third Y axis electrode 4c becomes larger, the second Y axis capacitance becomes smaller, and the acceleration on the Y axis can be obtained by detecting a difference of the changes of the first Y axis capacitance and the second Y axis capacitance.

Fig. 7 is a schematic structural diagram of a three-axis accelerometer according to the present invention at a predetermined time when acceleration is applied to the Z-axis. When acceleration exists on the Z axis, the elastic connecting

assemblies

71 and 72 elastically deform, the mass block 2 moves along the Z axis, the frame 60 rotates, the gap between the first Z axis electrode and the third Z axis electrode becomes larger or smaller to cause the capacitance of the first Z axis to become smaller or larger (the capacitance becomes smaller when the gap becomes larger, and the capacitance becomes larger when the gap becomes smaller), the gap between the second Z axis electrode and the fourth Z axis electrode becomes smaller or larger to cause the capacitance of the second Z axis to become larger or smaller (the capacitance of the second Z axis becomes smaller when the capacitance of the first Z axis becomes larger, and the capacitance of the second Z axis becomes larger when the capacitance of the first Z axis becomes smaller), and the acceleration on the Z axis is obtained by detecting the difference of the change of the capacitance of the first Z axis and the capacitance of the second Z axis. For example, as shown in fig. 7, when the mass 2 moves downward, the first beam column 61 of the frame 60 rotates downward, the first Z-axis capacitance becomes larger, the second beam column 62 rotates upward, the second Z-axis capacitance becomes smaller, and the acceleration on the Z-axis is detected by detecting the difference between the changes of the first Z-axis capacitance and the second Z-axis capacitance.

As shown in fig. 4, since the connection portion of the first elastic arm 51 and the fourth elastic portion 55 and the middle point of the neck portion 56 of the connection beam are spaced by a predetermined distance D along the X-axis direction, when there is acceleration in the Z-axis direction, the whole mass block 2 translates to drive the frame 60 to rotate, so that the first Z-axis capacitance and the second Z-axis capacitance are changed oppositely, thereby obtaining a fully differential signal of the Z-axis and improving the detection accuracy of the Z-axis.

In one embodiment, there may be only one anchor block, only one connecting beam, one frame, and only one elastic connecting assembly, wherein the elastic connecting assembly is elastically connected to the anchor block, the connecting beam, and the mass block.

In the present disclosure, the terms "connect", "connecting", and the like mean electrically connecting, and mean directly or indirectly electrically connecting if not specifically stated, and "couple" means directly or indirectly electrically connecting or coupling.

The foregoing description has disclosed fully the embodiments of the present invention. It should be noted that those skilled in the art can make modifications to the embodiments of the present invention without departing from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not to be limited to the specific embodiments described above.

Claims

1. A triaxial accelerometer, comprising:

a substrate;

an anchor block fixedly arranged on the substrate;

a first X-axis electrode, a second X-axis electrode, a first Y-axis electrode, a second Y-axis electrode, a first Z-axis electrode and a second Z-axis electrode which are fixedly arranged on the substrate;

a frame suspended above the substrate, the frame including a first beam column and a second beam column arranged opposite to each other, and a connection beam connecting the first beam column and the second beam column, the first beam column forming a third Z-axis electrode, the second beam column forming a fourth Z-axis electrode, wherein the first Z-axis electrode and the third Z-axis electrode are arranged opposite to each other to form a first Z-axis capacitor, and the second Z-axis electrode and the fourth Z-axis electrode are arranged opposite to each other to form a second Z-axis capacitor;

a mass block suspended above the substrate, wherein a third X-axis electrode and a third Y-axis electrode are formed on the mass block, the first X-axis electrode and the third X-axis electrode are oppositely arranged to form a first X-axis capacitor, the second X-axis electrode and the third X-axis electrode are oppositely arranged to form a second X-axis capacitor, the first Y-axis electrode and the third Y-axis electrode are oppositely arranged to form a first Y-axis capacitor, and the second Y-axis electrode and the third Y-axis electrode are oppositely arranged to form a second Y-axis capacitor; and

a spring coupling assembly configured to be resiliently coupled to the anchor block, the coupling beam, and the mass.

2. The tri-axial accelerometer of claim 1, wherein the frame, the proof mass, the spring coupling assembly, and the anchor block together form a proof mass electrode.

3. The tri-axial accelerometer of claim 1,

when acceleration exists on an X axis, the elastic connecting assembly deforms elastically, the mass block moves along the X axis, the change of the gap between the first X axis electrode and the third X axis electrode causes the change of the first X axis capacitance, the change of the gap between the second X axis electrode and the third X axis electrode causes the change of the second X axis capacitance, the change of the first X axis capacitance and the change of the second X axis capacitance are opposite, and the acceleration on the X axis is detected by detecting the change difference of the first X axis capacitance and the second X axis capacitance,

when acceleration exists on the Y axis, the elastic connecting assembly deforms elastically, the mass block moves along the Y axis, the change of the gap between the first Y-axis electrode and the third Y-axis electrode causes the change of the first Y-axis capacitance, the change of the gap between the second Y-axis electrode and the third Y-axis electrode causes the change of the second Y-axis capacitance, and the acceleration on the Y axis is detected by detecting the change difference between the first Y-axis capacitance and the second Y-axis capacitance,

when acceleration has on the Z axle, elastic connection subassembly elastic deformation, the quality piece removes along the Z axle, drives the frame rotates, and the clearance grow or diminish between first Z axle electrode and the third Z axle electrode leads to first Z axle electric capacity to diminish or grow, and the clearance between second Z axle electrode and the fourth Z axle electrode diminishes or the grow leads to second Z axle electric capacity grow or diminish, through the detection first Z axle electric capacity with the change of second Z axle electric capacity is poor, and then detects and obtain the epaxial acceleration of Z.

4. The triaxial accelerometer of claim 1, wherein the number of the anchor blocks is two, the two anchor blocks are respectively referred to as a first anchor block and a second anchor block, the first anchor block and the second anchor block are spaced apart, the number of the connecting beams is two, the two connecting beams are respectively referred to as a first connecting beam and a second connecting beam, two ends of each connecting beam are respectively connected to a first beam column and a second beam column, the frame defines a space, and the mass block is located in the frame,

the number of the elastic connecting assemblies is two, the two elastic connecting assemblies are respectively marked as a first elastic connecting assembly and a second elastic connecting assembly, the first elastic connecting assembly is elastically connected to the first anchor block, the first connecting beam and the mass block, and the second elastic connecting assembly is elastically connected to the second anchor block, the second connecting beam and the mass block.

5. The tri-axial accelerometer of claim 1, wherein the resilient linkage assembly comprises:

a connecting portion connected to the anchor block;

a first elastic part connected with one end of the connecting part;

a second elastic part connected with the other end of the connecting part;

a first elastic arm connected to the first elastic portion;

a second elastic arm connected to the second elastic portion;

a third elastic part connected between the first elastic arm and the second elastic arm;

a fourth elastic part connected between the first elastic arm and the middle part of the connecting beam, wherein a part of the first elastic arm connected with the fourth elastic part and a part of the connecting beam connected with the fourth elastic part are separated by a preset distance along the X-axis direction;

a fifth elastic part connected between the first elastic arm and one side of the mass block;

and a sixth elastic part connected between the second elastic arm and the other side of the mass block.

6. The tri-axial accelerometer of claim 5, wherein the fifth spring and the sixth spring each comprise a first spring extending in the Y-axis direction and a second spring extending in the X-axis direction, wherein the first spring is coupled to the mass and the second spring is coupled to the first spring arm or the second spring arm.

7. The tri-axial accelerometer of claim 5, wherein the connecting beam comprises a first end portion connected to the first beam-column, a second end portion connected to the second beam-column, and a middle portion between the first end portion and the second end portion, wherein the middle portion of the connecting beam comprises a neck portion on an inner side and a support portion on an outer side, a gap is provided between the neck portion and the support portion, one side of the support portion is connected to the second end portion, and the other end of the support portion is disconnected from the first end portion; the fourth elastic part is connected with the middle point of the neck part of the connecting beam.