Triaxial accelerometer based on single mass

Abstract

The present invention discloses a three-axis accelerometer, which comprises: 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 fixedly arranged on the substrate; a frame suspended above the substrate, which comprises a first beam and a second beam arranged relatively, the first beam forming a third Z-axis electrode, and the second beam forming a fourth Z-axis electrode; a mass block suspended above the substrate, the mass block having a third X-axis electrode and a third Y-axis electrode formed thereon; and an elastic connection component, which is configured to be elastically connected to the anchor block, the connecting beam and the mass block. The three-axis accelerometer of the present invention only needs one mass block to realize high-precision acceleration detection of three axes, especially to provide a full differential detection signal for the Z axis, which greatly improves the detection accuracy.

Description

[Technical field]

[0001] The invention relates to the field of MEMS (Micro-Electro-Mechanical System), and in particular to a three-axis accelerometer based on a single mass block. [Background technology]

[0002] MEMS accelerometers are widely used as a motion sensor. Compared with conventional accelerometers, they have the advantages of small size, light weight, low power consumption, low cost, good reliability, easy integration, strong overload capacity, and mass production. They have now become one of the main development directions of accelerometers and can be widely used in aerospace, automotive industry, industrial automation, robotics and other fields.

[0003] The working principle of common MEMS accelerometers is based on Newton's classical mechanics, and is generally composed of three parts: a sensitive mass block, a fixed bracket, and a detection circuit. The mass block is attached to the fixed bracket with the help of one or more elastic elements. When there is an external acceleration input, the sensitive mass block is displaced under the action of the inertial force. The magnitude and direction of the displacement have a certain corresponding relationship with the magnitude and direction of the input acceleration, and the displacement will cause certain related physical quantities (capacitance, pressure, resistance, resonant frequency, etc.) to change accordingly. Therefore, if the changes in these physical quantities can be converted into easily measurable electrical quantities such as voltage, current, frequency, etc. through the detection circuit, the displacement change of the mass block can be measured, thereby indirectly obtaining the information of the acceleration to be measured. In addition, according to the measured acceleration, the velocity of the sensitive mass block can be obtained after one integration operation, and the distance moved by the sensitive mass block can be obtained after two integration operations.

[0004] However, currently, one mass block is commonly used to measure the acceleration of two axes. Even if one mass block can be used to measure the acceleration of three axes, the detection accuracy of the Z axis is very low.

[0005] Therefore, it is necessary to provide a new improvement scheme to overcome the above problems. [Summary of the invention]

[0006] The technical problem to be solved by the present invention is to provide a three-axis accelerometer which can provide high-precision acceleration detection of three axes based on a mass block.

[0007] In order to solve the above problems, according to one aspect of the present invention, a three-axis accelerometer is provided, which 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 fixedly arranged on the substrate; a frame suspended above the substrate, which includes a first beam and a second beam arranged opposite to each other, and a connecting beam connecting the first beam and the second beam, the first beam forming a third Z-axis electrode, and the second beam 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, 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, on which a third X-axis electrode and a third Y-axis electrode are formed, wherein the first X-axis electrode and the third X-axis electrode are arranged opposite to each other to form a first X-axis capacitor, the second X-axis electrode and the third X-axis electrode are arranged opposite to each other to form a second X-axis capacitor, the first Y-axis electrode and the third Y-axis electrode are arranged opposite to each other to form a first Y-axis capacitor, and the second Y-axis electrode and the third Y-axis electrode are arranged opposite to each other to form a second Y-axis capacitor; and an elastic connection component, which is configured to be elastically connected to the anchor block, the connecting beam and the mass block.

[0008] In a preferred embodiment, the frame, the proof mass, the elastic connection assembly and the anchor block together form a proof mass electrode.

[0009] In a preferred embodiment, when there is acceleration on the X-axis, the elastic connection component is elastically deformed, the mass block moves along the X-axis, the gap between the first X-axis electrode and the third X-axis electrode changes, resulting in a change in the first X-axis capacitance, the gap between the second X-axis electrode and the third X-axis electrode changes, resulting in a change in the second X-axis capacitance, the first X-axis capacitance and the second X-axis capacitance change in opposite directions, and the acceleration on the X-axis is detected by detecting the change difference between the first X-axis capacitance and the second X-axis capacitance, and when there is acceleration on the Y-axis, the elastic connection component is elastically deformed, the mass block moves along the Y-axis, and the gap between the first Y-axis electrode and the third Y-axis electrode changes, resulting in a change in the first Y-axis capacitance. , the gap change between the second Y-axis electrode and the third Y-axis electrode causes the second Y-axis capacitance to change, 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 there is acceleration on the Z-axis, the elastic connection component elastically deforms, and the mass block moves along the Z-axis, driving the frame to rotate. The gap between the first Z-axis electrode and the third Z-axis electrode increases or decreases, causing the first Z-axis capacitance to decrease or increase, and the gap between the second Z-axis electrode and the fourth Z-axis electrode decreases or increases, causing the second Z-axis capacitance to increase or decrease. The acceleration on the Z-axis is detected by detecting the change difference between the first Z-axis capacitance and the second Z-axis capacitance.

[0010] Compared with the prior art, the three-axis accelerometer of the present invention only needs one mass block to achieve high-precision acceleration detection of three axes, especially providing a full differential detection signal for the Z axis, greatly improving the detection accuracy.

[0011] Other objects, features and advantages of the present invention will be described in detail below in conjunction with the accompanying drawings in the specific implementation manner.

Brief Description of the Drawings

[0012] The present invention will be more easily understood with reference to the accompanying drawings and the following detailed description, wherein like reference numerals correspond to like structural components, wherein:

[0013] Figure 1 is a schematic diagram of a top view of a three-axis accelerometer in one embodiment of the present invention;

[0014] Figure 2 The three-axis accelerometer in the present invention is Figure 1 Schematic diagram of the cross-sectional structure of the section line AA in FIG.

[0015] Figure 3 for Figure 1 An enlarged schematic diagram of a partial structure of a three-axis accelerometer;

[0016] Figure 4 for Figure 3 A further enlarged schematic diagram of the three-axis accelerometer in FIG.

[0017] Figure 5 It is a structural schematic diagram of the triaxial accelerometer in the present invention at a predetermined time when there is acceleration on the X-axis;

[0018] Figure 6 It is a structural schematic diagram of the three-axis accelerometer in the present invention at a predetermined time when there is acceleration on the Y axis;

[0019] Figure 7 It is a schematic structural diagram of the three-axis accelerometer in the present invention at a predetermined time when there is acceleration on the Z axis. [Specific implementation method]

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] The term "one embodiment" or "embodiment" as used herein means that a particular feature, structure or characteristic associated with the embodiment may be included in at least one implementation of the present invention. The term "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor does it necessarily refer to a separate or selected embodiment that is mutually exclusive with other embodiments. The terms "multiple" and "several" in the present invention mean two or more. The term "and / or" in the present invention means "and" or "or".

[0022] The present invention provides a three-axis accelerometer, which can provide high-precision acceleration detection of three axes based on a mass block.

[0023] Figure 1 FIG. 4 is a schematic diagram of a top view of the structure of a three-axis accelerometer in one embodiment of the present invention. Figure 2 The three-axis accelerometer in the present invention is Figure 1 Schematic diagram of the cross-sectional structure of the section line AA in. Figure 3 for Figure 1 An enlarged schematic diagram of part of the structure of the three-axis accelerometer. Figure 4 for Figure 3 A further enlarged schematic diagram of the three-axis accelerometer in FIG.

[0024] like Figure 1-2 As shown, the three-axis accelerometer 100 comprises:

[0025] substrate 10;

[0026] A first anchor block 1a and a second anchor block 1b fixedly disposed on the substrate 10;

[0027] 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;

[0028] A frame 60 suspended above the substrate 10 includes a first beam 61 and a second beam 62 arranged opposite to each other, a first connecting beam 63 and a second connecting beam 64 connecting the first beam 61 and the second beam, the first beam 61 forming a third Z-axis electrode 5a, the second beam 62 forming a fourth Z-axis electrode 5b, wherein the first Z-axis electrode 6a and the third Z-axis electrode 5a are arranged opposite to each other to form a first Z-axis capacitor, and the second Z-axis electrode 6b and the fourth Z-axis electrode 5b are arranged opposite to each other to form a second Z-axis capacitor;

[0029] 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 arranged oppositely to form a first X-axis capacitor, the second X-axis electrode 3b and the third X-axis electrode 3c are arranged oppositely to form a second X-axis capacitor, the first Y-axis electrode 4a and the third Y-axis electrode 4c are arranged oppositely to form a first Y-axis capacitor, and the second Y-axis electrode 4b and the third Y-axis electrode 4c are arranged oppositely to form a second Y-axis capacitor; and

[0030] A first elastic connection component 71 and a second elastic connection component 72, wherein the first elastic connection component 71 is elastically connected to the first anchor block 1a, the first connection beam 63 and the mass block 2, and the second elastic connection component 72 is elastically connected to the second anchor block 1b, the second connection beam 64 and the mass block 2.

[0031] In one embodiment, the frame 60, the mass block 2, the elastic connection components 71, 72, and the anchor blocks 1b and 1a together form a mass block electrode, that is, the potentials of these components are consistent, and they constitute the same electrode. For example, the frame 60, the mass block 2, the elastic connection components 71, 72, and the anchor blocks 1b and 1a can all be made of conductor or semiconductor materials or composite materials, and their potentials are consistent. In this way, the mass block electrode can provide a uniform potential 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 4c.

[0032] Combination Figure 1-4 As shown, each elastic connection assembly 71, 72 includes:

[0033] The connection portion 81 connected to the anchor blocks 1a and 1b (see Figure 4 );

[0034] A first elastic portion 53 connected to one end of the connecting portion 81;

[0035] A second elastic portion 66 connected to the other end of the connecting portion 81;

[0036] A first elastic arm 51 connected to the first elastic portion 53;

[0037] A second elastic arm 57 connected to the second elastic portion 66;

[0038] a third elastic portion 54 connected between the first elastic arm 51 and the second elastic arm 57;

[0039] The fourth elastic part 55 is connected between the first elastic arm 51 and the middle part of the connecting beam, and the portion where the first elastic arm 51 is connected to the fourth elastic part 55 and the portion where the connecting beam is connected to the fourth elastic part 55 are separated by a predetermined distance D along the X-axis direction (please refer to Figure 4 shown);

[0040] a fifth elastic portion 67 connected between the first elastic arm 51 and one side of the mass 2;

[0041] The sixth elastic portion 68 is connected between the second elastic arm 57 and the other side of the mass block 2 .

[0042] like Figure 1 and 3 As shown, the fifth elastic part 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 block 2, and the second elastic member 42 is connected to the first elastic arm 51. The sixth elastic part 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 block 2, and the second elastic member 44 is connected to the second elastic arm 57.

[0043] like Figure 3 and 4 As shown, 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 a middle portion located between the first end portion 52 and the second end portion 58. The middle portion of the connecting beams 63 and 64 includes a neck portion 56 located inside (see Figure 4 ) and a support portion 59 located on the outside, 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 52. There is a gap between the neck portion 56 and the support portion 59, the neck portion 56 makes the middle portion of the connecting beam more elastic, and the support portion 59 makes the middle portion stronger. The fourth elastic portion 55 is connected to the midpoint of the neck portion 56.

[0044] Figure 5It is a schematic diagram of the structure of the three-axis accelerometer in the present invention when there is acceleration on the X-axis at a predetermined time. When there is acceleration on the X-axis, the elastic connection components 71 and 72 are elastically deformed, the mass block 2 moves along the X, and the change in the gap between the X-axis electrodes causes the X-axis capacitance to change. For example, the gap between the first X-axis electrode 3a and the third X-axis electrode 3c becomes larger, and the first X-axis capacitance becomes smaller, and the gap between the second X-axis electrode 3b and the third X-axis electrode 3c becomes smaller, and the second X-axis capacitance becomes larger. For another example, the gap between the first X-axis electrode 3a and the third X-axis electrode 3c becomes smaller, and the first X-axis capacitance becomes larger, and the gap between the second X-axis electrode 3b and the third X-axis electrode 3c becomes larger, and the second X-axis capacitance becomes smaller. By detecting the difference in the change of the first X-axis capacitance and the second X-axis capacitance, the acceleration on the X-axis can be obtained. It should be known that Figure 5 And subsequent Figure 6 , 7 All of them are schematic diagrams of three-dimensional model demonstration of triaxial accelerometers. For ease of viewing, the movement range has greatly exceeded the actual movement range.

[0045] Figure 6 It is a structural schematic diagram of the three-axis accelerometer in the present invention at a predetermined time when there is acceleration on the Y axis. When there is acceleration on the Y axis, the elastic connection components 71 and 72 are elastically deformed, the mass block 2 moves along the Y axis, and the gap between the Y axis electrodes changes, resulting in a change in 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, and the second Y axis capacitance becomes larger. For another 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, and the second Y axis capacitance becomes smaller. By detecting the difference in the change of the first Y axis capacitance and the second Y axis capacitance, the acceleration on the Y axis can be obtained.

[0046] Figure 7 It is a schematic diagram of the structure of the three-axis accelerometer in the present invention when there is acceleration on the Z axis at a predetermined time. When there is acceleration on the Z axis, the elastic connection components 71 and 72 are elastically deformed, the mass block 2 moves along the Z axis, the frame 60 rotates, and the gap between the first Z axis electrode and the third Z axis electrode becomes larger or smaller, causing the first Z axis capacitance to become smaller or larger (the capacitance becomes smaller when the gap becomes larger, and the capacitance becomes larger when the gap becomes smaller), and the gap between the second Z axis electrode and the fourth Z axis electrode becomes smaller or larger, causing the second Z axis capacitance to become larger or smaller (the second Z axis capacitance becomes smaller when the first Z axis capacitance becomes larger, and the second Z axis capacitance becomes larger when the first Z axis capacitance becomes smaller). By detecting the difference in change between the first Z axis capacitance and the second Z axis capacitance, the acceleration on the Z axis is detected. For example, Figure 7As shown, at this time, the mass block 2 moves downward, the first beam 61 of the frame 60 rotates downward, the first Z-axis capacitance increases, the second beam 62 rotates upward, the second Z-axis capacitance decreases, and the acceleration on the Z-axis is detected by detecting the difference in change between the first Z-axis capacitance and the second Z-axis capacitance.

[0047] Please Figure 4 As shown, since the portion where the first elastic arm 51 is connected to the fourth elastic portion 55 and the midpoint of the neck 56 of the connecting beam are spaced a predetermined distance D in the X-axis direction, this asymmetric structure enables the entire mass block 2 to translate and drive the frame 60 to rotate when there is acceleration in the Z-axis direction, resulting in opposite changes in the first Z-axis capacitance and the second Z-axis capacitance, thereby obtaining a fully differential signal of the Z-axis and improving the Z-axis detection accuracy.

[0048] In one embodiment, there may be only one anchor block, in which case there is also only one connecting beam, the frame does not enclose a space, and there is only one elastic connecting component, which is elastically connected to the anchor block, the connecting beam and the mass block.

[0049] In the present invention, words such as “connect”, “connected”, “connect”, “connected”, etc. indicating electrical connection, unless otherwise specified, indicate direct or indirect electrical connection, and “coupled” indicates direct or indirect electrical connection or coupled connection.

[0050] The above description has fully disclosed the specific embodiments of the present invention. It should be pointed out that any changes made by those skilled in the art to the specific embodiments of the present invention do not deviate from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not limited to the above specific embodiments.

Claims

1. A three-axis accelerometer, characterized in that: It includes: substrate; An anchor block fixedly disposed 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 fixedly disposed on the substrate; a frame suspended above the substrate, comprising a first beam and a second beam arranged opposite to each other, and a connecting beam connecting the first beam and the second beam, wherein the first beam forms a third Z-axis electrode, and the second beam forms 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, wherein the first X-axis electrode and the third X-axis electrode are arranged oppositely to form a first X-axis capacitor, the second X-axis electrode and the third X-axis electrode are arranged oppositely to form a second X-axis capacitor, the first Y-axis electrode and the third Y-axis electrode are arranged oppositely to form a first Y-axis capacitor, and the second Y-axis electrode and the third Y-axis electrode are arranged oppositely to form a second Y-axis capacitor; and an elastic connection component, configured to be elastically connected to the anchor block, the connection beam and the mass block, When there is acceleration on the X-axis, the elastic connection component is elastically deformed, the mass block moves along the X-axis, the gap change between the first X-axis electrode and the third X-axis electrode causes the first X-axis capacitance to change, the gap change between the second X-axis electrode and the third X-axis electrode causes the second X-axis capacitance to change, the first X-axis capacitance and the second X-axis capacitance change in opposite directions, and the acceleration on the X-axis is detected by detecting the change difference between the first X-axis capacitance and the second X-axis capacitance. When there is acceleration on the Y-axis, the elastic connection component is elastically deformed, the mass block moves along the Y-axis, the gap change between the first Y-axis electrode and the third Y-axis electrode causes the first Y-axis capacitance to change, and the gap change between the second Y-axis electrode and the third Y-axis electrode causes the second Y-axis capacitance to change. 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 there is acceleration on the Z-axis, the elastic connection component elastically deforms, the mass block moves along the Z-axis, driving the frame to rotate, the gap between the first Z-axis electrode and the third Z-axis electrode increases or decreases, causing the first Z-axis capacitance to decrease or increase, and the gap between the second Z-axis electrode and the fourth Z-axis electrode decreases or increases, causing the second Z-axis capacitance to increase or decrease. By detecting the difference in change between the first Z-axis capacitance and the second Z-axis capacitance, the acceleration on the Z-axis is detected.

2. The three-axis accelerometer according to claim 1, characterized in that: The frame, the proof mass, the elastic connection assembly and the anchor block together form a proof mass electrode.

3. The three-axis accelerometer according to claim 1, characterized in that: The number of the anchor blocks is two, and the two anchor blocks are respectively recorded as the first anchor block and the second anchor block. The first anchor block and the second anchor block are arranged at an interval. The number of the connecting beams is two, and the two connecting beams are respectively recorded as the first connecting beam and the second connecting beam. Both ends of each connecting beam are respectively connected to the first beam column and the second beam column. The frame encloses a space, and the mass block is located in the frame. The number of the elastic connection components is two, and the two elastic connection components are respectively recorded as a first elastic connection component and a second elastic connection component. The first elastic connection component is elastically connected to the first anchor block, the first connecting beam and the mass block, and the second elastic connection component is elastically connected to the second anchor block, the second connecting beam and the mass block.

4. The three-axis accelerometer according to claim 1, characterized in that: The elastic connection assembly comprises: A connecting portion connected to the anchor block; a first elastic portion connected to one end of the connecting portion; a second elastic portion connected to the other end of the connecting portion; a first elastic arm connected to the first elastic portion; a second elastic arm connected to the second elastic portion; a third elastic portion connected between the first elastic arm and the second elastic arm; a fourth elastic portion connected between the first elastic arm and the middle portion of the connecting beam, wherein a portion where the first elastic arm is connected to the fourth elastic portion and a portion where the connecting beam is connected to the fourth elastic portion are spaced a predetermined distance apart along the X-axis direction; a fifth elastic portion connected between the first elastic arm and one side of the mass; A sixth elastic portion is connected between the second elastic arm and the other side of the mass block.

5. The three-axis accelerometer according to claim 4, characterized in that: The fifth elastic part and the sixth elastic part each include a first elastic member extending in the Y-axis direction and a second elastic member extending in the X-axis direction, wherein the first elastic member is connected to the mass block, and the second elastic member is connected to the first elastic arm or the second elastic arm.

6. The three-axis accelerometer according to claim 4, characterized in that: The connecting beam comprises a first end connected to the first beam column, a second end connected to the second beam column, and a middle portion located between the first end and the second end, and the middle portion of the connecting beam comprises a neck portion located on the inner side and a support portion located on the outer side. A support portion, a gap is provided between the neck and the support portion, and one side of the support portion is connected to the second end portion, The other end is disconnected from the first end; and the fourth elastic portion is connected to the midpoint of the neck of the connecting beam.

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