Three-axis capacitive accelerometer

Abstract

The utility model relates to the technical field of accelerometers, and discloses a triaxial capacitive accelerometer, which comprises an anchor point, and further comprises a first acceleration detection assembly, a second acceleration detection assembly, a third acceleration detection assembly, a fourth acceleration detection assembly, a fifth acceleration detection assembly and a sixth acceleration detection assembly which are sequentially arranged from outside to inside, the second acceleration detection assembly comprises a second mass block and a second detection electrode, and the second mass block and the first mass block are elastically connected in the second direction; the third acceleration detection assembly comprises a third mass block and a third detection electrode, the third mass block and the second mass block are elastically connected in the third direction, and the third detection electrode is a third direction differential capacitor. The triaxial capacitive accelerometer disclosed by the utility model has the advantages of simple structure and few anchor points, is suitable for an application scene of long-time stable work, prolongs the service life of the accelerometer, and improves the reliability of the accelerometer.

Description

TECHNICAL FIELD

[0001] The utility model relates to accelerometer technical field especially relates to a three -axis capacitive accelerometer. BACKGROUND

[0002] The existing three -axis accelerometer usually adopts three independent sensors and complex structure to realize its function, causes the overall integration to be poor. This not only increases the size and weight of the equipment, but also can influence its performance and reliability. Since multiple independent sensors are used to measure acceleration on different axes, such structure often has difficulty in realizing highly integrated design, which can lead to large size and weight of the device, and is inconvenient to carry and use. In addition, signal transmission and processing between multiple independent sensors can also cause delay and interference, further affecting the performance of the device.

[0003] In order to solve the above problems, the prior art realizes the acceleration detection of three directions through integrated design, but the existing three -axis integrated accelerometer still has the problems of complex structure and many anchor points. The complex structure increases the production cost of the accelerometer, and the large number of anchor points causes stress to concentrate in the local area, which can cause fatigue and damage, and is not suitable for long time stable working application scene, resulting in short service life and low reliability of the accelerometer. SUMMARY

[0004] Based on the above, the utility model aims at providing a three -axis capacitive accelerometer, which has simple structure, few anchor points, is suitable for long time stable working application scene, prolongs the service life of the accelerometer, and improves the reliability of the accelerometer.

[0005] To achieve the above purpose, the utility model adopts the following technical scheme:

[0006] A three -axis capacitive accelerometer, comprising an anchor point fixed on a substrate, further comprising, from outside to inside:

[0007] A first acceleration detection assembly for detecting first acceleration in a first direction and comprising a first mass and a first detection electrode, the first mass being elastically connected with the anchor point along the first direction, and a movable part of the first detection electrode being arranged on the first mass;

[0008] A second acceleration detection assembly for detecting second acceleration in a second direction and comprising a second mass and a second detection electrode, the second mass being elastically connected with the first mass along the second direction, and a movable part of the second detection electrode being arranged on the second mass;

[0009] a third acceleration detecting assembly for detecting a third acceleration in a third direction and comprising a third mass and a third detecting electrode, the third mass being elastically connected with the second mass in the third direction, the third detecting electrode being a third direction differential capacitor and its movable part being arranged on the third mass;

[0010] the third direction differential capacitor comprising a third direction negative differential electrode and a third direction positive differential electrode, the third direction negative differential electrode and the third direction positive differential electrode being arranged on the third mass in a spaced manner, the third direction negative differential electrode being a first comb electrode, the first comb electrode comprising first static combs and first dynamic combs arranged alternately in sequence, the third direction positive differential electrode being a second comb electrode, the second comb electrode comprising second static combs and second dynamic combs arranged alternately in sequence, when detecting the third acceleration, the third mass moves in the third direction, the first dynamic combs move in the third direction and the facing area of the two is a first overlapping area, the second dynamic combs move in the third direction and the facing area of the two is a second overlapping area, the second overlapping area and the first overlapping area change in opposite directions;

[0011] the first comb electrode further comprising a first comb fixed shaft fixed on the substrate, the first static combs being fixed on the first comb fixed shaft, the first static combs being formed by the first comb fixed shaft extending in the third direction from the side away from the substrate, the first dynamic combs being formed by the third mass extending in the third direction from the side close to the substrate;

[0012] the second comb electrode further comprising a second comb fixed shaft fixed on the substrate, the second static combs being fixed on the second comb fixed shaft, the second static combs being formed by the second comb fixed shaft extending in the third direction from the side close to the substrate, the second dynamic combs being formed by the third mass extending in the third direction from the side away from the substrate;

[0013] when the third mass moves in the direction close to the substrate, the first overlapping area gradually decreases and the second overlapping area gradually increases; when the third mass moves in the direction away from the substrate, the first overlapping area gradually increases and the second overlapping area gradually decreases.

[0014] As a preferred scheme of the three-axis capacitive accelerometer, the third mass is a central square block, the number of the third direction negative differential electrode and the third direction positive differential electrode is two, the third direction negative differential electrode and the third direction positive differential electrode are arranged alternately on the four edges of the central square block, and the two third direction negative differential electrodes and the two third direction positive differential electrodes form a differential capacitor.

[0015] As a preferred solution of the tri-axial capacitive accelerometer, the first acceleration detection assembly comprises a first elastic connecting beam capable of stretching and contracting along the first direction, one end of the first elastic connecting beam being connected with the anchor point, and the other end of the first elastic connecting beam being connected with the first mass block.

[0016] As a preferred solution of the tri-axial capacitive accelerometer, the first mass block is provided with a receiving groove, the receiving groove is a cross groove, the first mass block is a first square block, each corner of the first square block is provided with a first avoiding groove, the number of the anchor points and the first elastic connecting beams is at least four, and each of the first avoiding grooves is provided with at least one anchor point and at least one first elastic connecting beam.

[0017] As a preferred solution of the tri-axial capacitive accelerometer, the second acceleration detection assembly further comprises a second elastic connecting beam capable of stretching and contracting along the second direction, two ends of the second elastic connecting beam being connected with the first mass block and the second mass block respectively.

[0018] As a preferred solution of the tri-axial capacitive accelerometer, the second mass block is a second square block, each corner of the second square block is provided with a second avoiding groove, the number of the second elastic connecting beams is at least four, each of the second avoiding grooves is provided with at least one second elastic connecting beam, and the second square block is provided with a square groove for accommodating the third mass block.

[0019] As a preferred solution of the tri-axial capacitive accelerometer, the third acceleration detection assembly further comprises a third elastic connecting beam capable of deforming along the third direction, two ends of the third elastic connecting beam being connected with the second mass block and the third mass block respectively.

[0020] As a preferred solution of the tri-axial capacitive accelerometer, the first detection electrode is arranged on both sides of the first mass block along the first direction and is a third comb electrode, the third comb electrode comprises third dynamic comb teeth and third static comb teeth arranged alternately, when detecting the first acceleration, the third dynamic comb teeth move along the first direction with the first mass block, and the third overlapping area between the third dynamic comb teeth and the third static comb teeth changes.

[0021] The second detection electrode is arranged on both sides of the second mass block along the second direction and is a fourth comb electrode, the fourth comb electrode comprises fourth dynamic comb teeth and fourth static comb teeth arranged alternately, when detecting the second acceleration, the fourth dynamic comb teeth move along the second direction with the second mass block, and the fourth overlapping area between the fourth dynamic comb teeth and the fourth static comb teeth changes.

[0022] The utility model discloses the beneficial effect is:

[0023] The utility model discloses a three -axis capacitance accelerometer, its simple design, high integration and convenient to manufacture, in this three -axis capacitance accelerometer, only first mass block and anchor point are elastically connected along the first direction, and second mass block is elastically connected with first mass block, similarly, third mass block is also elastically connected with second mass block, and such configuration makes second mass block and third mass block all need not additional anchor point structure, reduces the number of anchor point, helps to reduce stress concentration phenomenon, thereby reduce the possibility of local fatigue and damage, make this accelerometer be very suitable for the occasion needing long time stable operation, these improvements not only prolong the life of accelerometer, also significantly improved its overall reliability. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical scheme in the embodiment of the utility model, the following will be needed to use the drawing in the embodiment of the utility model is briefly introduced, and obviously, the drawing in the following description is only some embodiments of the utility model, and for those skilled in the art, under the premise of not creating labor, other drawings can also be obtained according to the content of the embodiment of the utility model and these drawings.

[0025] Figure 1 It is the schematic diagram of three -axis capacitance accelerometer provided by the embodiment of the utility model;

[0026] Figure 2 It is the schematic diagram of part structure of three -axis capacitance accelerometer provided by the embodiment of the utility model;

[0027] Figure 3 It is the longitudinal section view of the comb tooth of the first comb electrode of three -axis capacitance accelerometer provided by the embodiment of the utility model;

[0028] Figure 4 It is the longitudinal section view of the comb tooth of the second comb electrode of three -axis capacitance accelerometer provided by the embodiment of the utility model.

[0029] In the drawing:

[0030] 1, anchor point;

[0031] 21, first mass block;2101, accommodating groove;2102, first avoiding slot;22, first detection electrode;221, third dynamic comb tooth;222, third static comb tooth;23, first elastic connecting beam;

[0032] 31, second mass block;3101, second avoiding slot;32, second detection electrode;321, fourth dynamic comb tooth;322, fourth static comb tooth;33, second elastic connecting beam;

[0033] 41, third mass; 410, weight-reducing cavity; 42, third detection electrode; 4201, first comb electrode; 42011, first static comb; 42012, first dynamic comb; 42013, first comb fixing shaft; 4202, second comb electrode; 42021, second static comb; 42022, second dynamic comb; 42023, second comb fixing shaft; 43, third elastic connecting beam. DETAILED DESCRIPTION

[0034] In order to make the technical problems solved by the utility model, the technical scheme adopted and the technical effects reached more clear, the technical scheme of the embodiments of the utility model will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0035] In the description of the utility model, it needs to be explained that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like is the orientation or position relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model. In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0036] In the description of the utility model, it needs to be explained that unless otherwise explicitly specified and limited, the terms "mounting", "connection" and "connection" should be understood broadly, for example, it can be fixed connection, and can also be detachable connection; it can be mechanical connection, and can also be electrical connection; it can be directly connected, and can also be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0037] The embodiment provides a three-axis capacitive accelerometer, which comprises Figure 1 And Figure 2As shown, the three-axis capacitive accelerometer comprises an anchor point 1 fixed on a substrate, and further comprises a first acceleration detection assembly, a second acceleration detection assembly and a third acceleration detection assembly arranged from outside to inside, the first acceleration detection assembly is used for detecting a first acceleration in a first direction and comprises a first mass 21 and a first detection electrode 22, the first mass 21 is elastically connected with the anchor point 1 along the first direction, and a movable part of the first detection electrode 22 is arranged on the first mass 21. The second acceleration detection assembly is used for detecting a second acceleration in a second direction and comprises a second mass 31 and a second detection electrode 32, the second mass 31 is elastically connected with the first mass 21 along the second direction, and a movable part of the second detection electrode 32 is arranged on the second mass 31. The third acceleration detection assembly is used for detecting a third acceleration in a third direction and comprises a third mass 41 and a third detection electrode 42, the third mass 41 is elastically connected with the second mass 31 along the third direction, the third detection electrode 42 is a differential capacitance in the third direction, and a movable part of the third detection electrode 42 is arranged on the third mass 41, and the third acceleration in the third direction is detected by using the differential capacitance to inhibit the same direction error.

[0038] As shown in the drawings, Figure 1 The first direction of the embodiment is the X-axis direction, the second direction is the Y-axis direction, and the third direction is the Z-axis direction, and the X-axis direction, the Y-axis direction and the Z-axis direction are perpendicular to each other. The first acceleration detection assembly is used for detecting the first acceleration in the X-axis direction, the second acceleration detection assembly is used for detecting the second acceleration in the Y-axis direction, and the third acceleration detection assembly is used for detecting the third acceleration in the Z-axis direction. In other embodiments of the utility model, the first direction, the second direction and the third direction are not limited to this limitation in the embodiment, and can also be that the first direction is the Y-axis direction, the second direction is the X-axis direction, and the third direction is the Z-axis direction, or the first direction, the second direction and the third direction are other directions, and are specifically set according to actual needs.

[0039] The three-axis capacitive accelerometer provided by the embodiment is simple in design, high in integration and convenient to manufacture, in the three-axis capacitive accelerometer, only the first mass 21 is elastically connected with the anchor point 1 along the first direction, the second mass 31 is elastically connected with the first mass 21, and similarly, the third mass 41 is also elastically connected with the second mass 31, and such configuration makes the second mass 31 and the third mass 41 both unnecessary to have an additional anchor point structure, thereby reducing the number of anchor points, which helps to reduce the stress concentration phenomenon, thereby reducing the possibility of local fatigue and damage, so that the accelerometer is very suitable for occasions requiring long-time stable operation, and these improvements not only prolong the service life of the accelerometer, but also significantly improve the overall reliability of the accelerometer.

[0040] Specifically, as shown in the drawings, Figure 2As shown, the third mass block 41 of the embodiment is a central square block, and a weight-reducing cavity 410 is arranged at the center of the central square block, and the cross-sectional shape of the weight-reducing cavity 410 is a square. Figure 2 As shown, the third detection electrode 42 includes two third-direction negative differential electrodes and two third-direction positive differential electrodes, and the third-direction negative differential electrodes and the third-direction positive differential electrodes are alternately arranged on four sides of the central square block and constitute differential capacitors. Specifically, the number of the third-direction negative differential electrodes and the third-direction positive differential electrodes is two, the two third-direction negative differential electrodes are arranged on two sides of the third mass block 41 arranged opposite to each other along the X-axis direction, and the two third-direction positive differential electrodes are arranged on two sides of the third mass block 41 arranged opposite to each other along the Y-axis direction.

[0041] Further, as shown in Figure 2 As shown, the third-direction negative differential electrode of the embodiment is a first comb electrode 4201, the first comb electrode 4201 includes first static combs 42011 and first dynamic combs 42012 arranged alternately, the third-direction positive differential electrode is a second comb electrode 4202, the second comb electrode 4202 includes second static combs 42021 and second dynamic combs 42022 arranged alternately, and when the third acceleration is detected, the third mass block 41 moves along the third direction, the first dynamic comb 42012 moves along the Z-axis direction, and the opposite area of the two is a first overlapping area, the second dynamic comb 42022 moves along the Z-axis direction, and the opposite area of the two is a second overlapping area, the second overlapping area and the first overlapping area change in opposite directions, that is, when the first overlapping area increases, the second overlapping area decreases, and when the first overlapping area decreases, the second overlapping area increases. This variable-area detection method has better linearity and higher accuracy than the variable-gap detection, and is beneficial to the detection of the third acceleration in the Z-axis direction.

[0042] It should be noted that in other embodiments of the utility model, the shape of the third mass block 41 is not limited to the square of the embodiment, and can also be circular or other shapes, and the number of the third-direction negative differential electrodes and the third-direction positive differential electrodes is not limited to two of the embodiment, and can also be one or more than two, which is specifically arranged according to actual needs.

[0043] Specifically, as shown in Figure 2 and Figure 3 As shown, the first comb electrode 4201 further includes a first comb fixed shaft 42013 fixed on the substrate, the first static comb 42011 is fixed on the first comb fixed shaft 42013, and the first static comb 42011 is formed by extending from the side of the first comb fixed shaft 42013 away from the substrate to the direction close to the substrate along the third direction, and the first dynamic comb 42012 is formed by extending from the side of the third mass block 41 close to the substrate to the direction away from the substrate along the third direction. As shown in Figure 2 andFigure 4 As shown, the second comb electrode 4202 further comprises a second comb fixed shaft 42023 fixed on the substrate, the second static comb 42021 is fixed on the second comb fixed shaft 42023, and the second static comb 42021 is formed by the second comb fixed shaft 42023 extending along the third direction from the side close to the substrate to the direction away from the substrate, and the second dynamic comb 42022 is formed by the third mass 41 extending along the third direction from the side away from the substrate to the direction close to the substrate. When the third mass 41 moves along the direction close to the substrate, the first overlapping area gradually decreases, and the second overlapping area gradually increases; when the third mass 41 moves along the direction away from the substrate, the first overlapping area gradually increases, and the second overlapping area gradually decreases. Therefore, the detection mode of the third acceleration is translational detection, and the overall symmetry of the accelerometer is high. Compared with the traditional detection mode using a seesaw, the detection accuracy and sensitivity are greatly improved.

[0044] As shown in Figure 1 The first acceleration detection assembly comprises a first elastic connecting beam 23 capable of stretching and contracting along a first direction, one end of the first elastic connecting beam 23 is connected with the anchor point 1, and the other end of the first elastic connecting beam 23 is connected with the first mass 21. Figure 1 As shown in The first mass 21 is provided with a containing groove 2101, and the second acceleration detection assembly is arranged in the containing groove 2101. The containing groove 2101 is a cross groove, the first mass 21 is a first square block, each corner of the first square block is provided with a first avoiding groove 2102, the number of the anchor points 1 and the first elastic connecting beams 23 is four, one anchor point 1 and one first elastic connecting beam 23 are arranged in each first avoiding groove 2102, and each first elastic connecting beam 23 corresponds to one anchor point 1. The first elastic connecting beam 23 is a first U-shaped beam, one end of the first U-shaped beam is connected with the anchor point 1, and the other end of the first U-shaped beam is connected with the first mass 21.

[0045] Figure 1 As shown in Figure 1 The second acceleration detection assembly further comprises a second elastic connecting beam 33 capable of stretching and contracting along a second direction, and two ends of the second elastic connecting beam 33 are connected with the first mass 21 and the second mass 31 respectively. As shown in

[0046] The second mass 31 is a second square block, each corner of the second square block is provided with a second avoiding groove 3101, the number of the second elastic connecting beams 33 is four, one second elastic connecting beam 33 is arranged in each second avoiding groove 3101, and the second square block is provided with a square groove for containing the third mass 41. The second elastic connecting beam 33 is a second U-shaped beam, one end of the second U-shaped beam is connected with the first mass 21, and the other end of the second U-shaped beam is connected with the second mass 31. Figure 1As shown, the first detection electrode 22 is arranged on the opposite sides of the first mass 21 along the first direction, and the first detection electrode 22 is a third comb electrode, which comprises third dynamic comb teeth 221 and third static comb teeth 222 arranged alternately in sequence. When the first acceleration is detected, the third dynamic comb teeth 221 move along the first direction with the first mass 21, and the third overlapping area between the third dynamic comb teeth 221 and the third static comb teeth 222 changes. The second detection electrode 32 is arranged on the two sides of the second mass 31 along the second direction, and is a fourth comb electrode, which comprises fourth dynamic comb teeth 321 and fourth static comb teeth 322 arranged alternately in sequence. When the second acceleration is detected, the fourth dynamic comb teeth 321 move along the second direction with the second mass 31, and the fourth overlapping area between the fourth dynamic comb teeth 321 and the fourth static comb teeth 322 changes.

[0047] As shown in the figure, Figure 1 The third acceleration detection assembly further comprises a third elastic connecting beam 43 capable of deforming along the third direction, and the two ends of the third elastic connecting beam 43 are connected with the second mass 31 and the third mass 41 respectively. The third elastic connecting beam 43 comprises a first short beam, a straight beam and a second short beam. The first short beam and the second short beam are arranged at the two ends of the straight beam respectively and are located on the two sides of the straight beam respectively. In the natural state, the first short beam and the second short beam are both perpendicular to the straight beam. The first short beam is connected with the second mass 31, and the second short beam is connected with the third mass 41. The lengths of the first short beam and the second short beam are shorter, and the length of the straight beam is longer. When the third mass 41 is subjected to a force in the Z-axis direction under the action of the third acceleration in the Z-axis direction, the third elastic connecting beam 43 can deform to ensure that the third mass 41 moves along the Z-axis direction, so that the third detection electrode 42 detects the capacitance change caused by the movement of the third mass 41 along the Z-axis direction, and further realizes the detection of the third acceleration.

[0048] The first detection electrode 22 of the embodiment comprises a first direction positive electrode and a first direction negative electrode. The first direction positive electrode and the first direction negative electrode have the same structure, and the number of comb teeth is N x The overlapping thickness along the Z-axis direction in the natural state is h x The gap along the Y-axis direction between adjacent two comb teeth is d x The capacitance change of the first direction positive electrode is ΔC x+ The capacitance change of the first direction negative electrode is ΔC x- The second detection electrode 32 comprises a second direction positive electrode and a second direction negative electrode. The second direction positive electrode and the second direction negative electrode have the same structure, and the number of comb teeth is N y The overlapping thickness along the Z-axis direction in the natural state is h y The gap along the X-axis direction between adjacent two comb teeth is d y The capacitance change of the second direction positive electrode is ΔCy+ The capacitance variation of the second direction negative electrode is ΔC y- The structure of the third direction negative differential electrode and the third direction positive differential electrode is the same, and the number of the combs is N z The overlapping thickness along the Z-axis direction in the natural state is h z The gap of the adjacent two combs of the third direction negative differential electrode along the Y-axis direction is d z The gap of the adjacent two combs of the third direction positive differential electrode along the X-axis direction is also d Z The capacitance variation of the third direction negative differential electrode is ΔC z- The capacitance variation of the third direction positive differential electrode is ΔC z+ .

[0049] The calculation formula when the first acceleration detection assembly, the second acceleration detection assembly and the third acceleration detection assembly respectively detect the first acceleration in the first direction, the second acceleration in the second direction and the third acceleration in the third direction is analyzed in detail below, and the formula is used to illustrate that each acceleration detection assembly is not affected by the acceleration in other directions.

[0050] When detecting the first acceleration in the X direction, the first mass 21 moves along the X-axis direction, and the capacitance variation of the first detection electrode 22 is:

[0051]

[0052] In the formula, x is the displacement of the first direction positive electrode and the first direction negative electrode along the X-axis direction under the action of the first acceleration, w x is the frequency when the accelerometer detects the first acceleration, a x is the size of the first acceleration along the X-axis direction.

[0053] At this time, the second mass 31 moves along the X-axis direction with the first mass 21 under the driving of the second elastic connecting beam 33, and the capacitance variation of the second detection electrode 32 is:

[0054]

[0055] ΔC y总 = ΔC y+ - ΔC y- = 0

[0056] In the formula, ly is the length of the overlapping length of the second direction positive electrode and the second direction negative electrode along the length direction of the comb in the natural state under the action of the first acceleration, and x is the displacement of the second direction positive electrode and the second direction negative electrode along the X-axis direction, which is the same as the displacement of the first detection electrode 22.

[0057] At this time, the third mass 41 moves along the X-axis direction with the second mass 31 under the drive of the third elastic connecting beam 43, and the capacitance change of the third detection electrode 42 is:

[0058]

[0059] ΔC z总 = ΔG z+ - ΔC z- = 0

[0060] In the formula, l z is the length of the third direction negative differential electrode and the third direction positive differential electrode overlapping along the length direction of the comb teeth in the natural state under the action of the first acceleration, and x is the displacement of the third direction negative differential electrode and the third direction positive differential electrode along the X-axis direction, and is the same as the displacement of the first detection electrode 22.

[0061] Therefore, when detecting the acceleration along the X-axis direction, only the capacitance of the first detection electrode 22 changes, and the capacitances of the second detection electrode 32 and the third detection electrode 42 do not change.

[0062] When detecting the second acceleration along the Y-axis direction, the second mass 31 moves along the Y-axis direction, the second elastic connecting beam 33 deforms along the Y-axis direction, and the first mass 21 does not move along the X-axis direction, that is, the capacitance of the first detection electrode 22 along the X-axis direction does not change, the capacitance of the second detection electrode 32 changes, and the capacitance change of the second detection electrode 32 along the Y-axis direction is:

[0063]

[0064] In the formula, y is the displacement of the second direction positive electrode and the second direction negative electrode along the Y-axis direction, a y is the size of the second acceleration along the Y-axis direction, and w y is the frequency when the accelerometer detects the second acceleration.

[0065] At this time, the third mass 41 moves along the Y-axis direction with the second mass 31 under the drive of the third elastic connecting beam 43, and the capacitance change of the third detection electrode 42 is:

[0066]

[0067] ΔC z总 = ΔC z+ - ΔC z- = 0

[0068] In the formula, y is the displacement of the third direction negative differential electrode and the third direction positive differential electrode along the Y-axis direction, and is the same as the displacement of the second detection electrode 32.

[0069] Therefore, when detecting the second acceleration in the Y-axis direction, only the capacitance of the second detection electrode 32 changes, and the capacitances of the first detection electrode 22 and the third detection electrode 42 do not change.

[0070] When detecting the third acceleration in the Z-axis direction, the third mass block 41 moves in the Z-axis direction, the third elastic connecting beam 43 deforms in the Z-axis direction, the second mass block 31 does not move in the Z-axis direction with the third mass block 41, and the first mass block 21 also does not move in the Z-axis direction, so the capacitances of the first detection electrode 22 and the second detection electrode 32 do not change, and the capacitance of the third detection electrode 42 changes.

[0071]

[0072] In the formula, z is the displacement of the third direction negative differential electrode and the third direction positive differential electrode in the Z-axis direction, a z is the size of the second acceleration in the Z-axis direction, w z is the frequency when the accelerometer detects the third acceleration.

[0073] It should be noted that the above are only preferred embodiments of the present application and the technical principles applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, re-adjustments and substitutions without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A three-axis capacitive accelerometer, characterized in that: It includes anchor points fixed on the substrate, and also includes the following points arranged from the outside to the inside: a first acceleration detection assembly, configured to detect a first acceleration in a first direction and comprising a first mass and a first detection electrode, wherein the first mass is elastically connected to the anchor point along the first direction, and a movable portion of the first detection electrode is disposed on the first mass; a second acceleration detection assembly, configured to detect a second acceleration in a second direction and comprising a second mass and a second detection electrode, the second mass being elastically connected to the first mass along the second direction, the movable portion of the second detection electrode being disposed on the second mass; a third acceleration detection assembly for detecting a third acceleration in a third direction and comprising a third mass block and a third detection electrode, wherein the third mass block is elastically connected to the second mass block along the third direction, and the third detection electrode is a third-direction differential capacitor, and a movable portion thereof is disposed on the third mass block; the third acceleration detection assembly further comprises a third elastic connecting beam capable of deforming along the third direction, wherein two ends of the third elastic connecting beam are respectively connected to the second mass block and the third mass block, wherein the third elastic connecting beam comprises a first short beam, a straight beam, and a second short beam, wherein the first short beam and the second short beam are respectively disposed at two ends of the straight beam and on both sides of the straight beam, the first short beam is connected to the second mass block, and the second short beam is connected to the third mass block; The third-direction differential capacitor includes a third-direction negative differential electrode and a third-direction positive differential electrode, the third-direction negative differential electrode and the third-direction positive differential electrode are arranged on the third mass block with an interval, the third-direction negative differential electrode is a first comb-tooth electrode, the first comb-tooth electrode includes a first static comb tooth and a first movable comb tooth that are alternately arranged in sequence, the third-direction positive differential electrode is a second comb-tooth electrode, the second comb-tooth electrode includes a second static comb tooth and a second movable comb tooth that are alternately arranged in sequence, when detecting the third acceleration, the third mass block moves along the third direction, the first movable comb tooth moves along the third direction, and the area facing each other is a first overlapping area, the second movable comb tooth moves along the third direction, and the area facing each other is a second overlapping area, and the second overlapping area changes in the opposite direction to the first overlapping area; The first comb-tooth electrode further includes a first comb-tooth fixing shaft fixed on the substrate, the first stationary comb teeth are fixed on the first comb-tooth fixing shaft, the first stationary comb teeth are formed by extending along the third direction from a side of the first comb-tooth fixing shaft facing away from the substrate, and the first movable comb teeth are formed by extending along the third direction from a side of the third mass close to the substrate; The second comb-tooth electrode further includes a second comb-tooth fixing shaft fixed on the substrate, the second stationary comb teeth are fixed on the second comb-tooth fixing shaft, the second stationary comb teeth are formed by extending along the third direction from a side of the second comb-tooth fixing shaft close to the substrate, and the second movable comb teeth are formed by extending along the third direction from a side of the third mass away from the substrate; When the third mass moves in a direction close to the substrate, the first overlapping area gradually decreases and the second overlapping area gradually increases; when the third mass moves in a direction away from the substrate, the first overlapping area gradually increases and the second overlapping area gradually decreases.

2. The three-axis capacitive accelerometer according to claim 1, wherein: The third mass block is a central square block, the number of the third-direction negative differential electrodes and the third-direction positive differential electrodes are both two, the third-direction negative differential electrodes and the third-direction positive differential electrodes are alternately arranged on the four sides of the central square block, and the two third-direction negative differential electrodes and the two third-direction positive differential electrodes form a differential capacitor.

3. The three-axis capacitive accelerometer according to claim 1, wherein: The first acceleration detection component includes a first elastic connecting beam that can be extended and retracted along the first direction, one end of the first elastic connecting beam is connected to the anchor point, and the other end of the first elastic connecting beam is connected to the first mass block.

4. The three-axis capacitive accelerometer according to claim 3, wherein: A accommodating groove is provided in the first mass block, and the accommodating groove is a cross groove. The first mass block is a first square block, and a first avoidance groove is provided at each corner of the first square block. The number of the anchor points and the first elastic connecting beams is at least four, and each of the first avoidance grooves is provided with at least one anchor point and at least one first elastic connecting beam.

5. The three-axis capacitive accelerometer according to claim 1, wherein: The second acceleration detection assembly further includes a second elastic connecting beam capable of extending and retracting along the second direction, and two ends of the second elastic connecting beam are respectively connected to the first mass block and the second mass block.

6. The three-axis capacitive accelerometer according to claim 5, characterized in that: The second mass block is a second square block, and a second avoidance groove is provided at each corner of the second square block. The number of the second elastic connecting beams is at least four, and each of the second avoidance grooves is provided with at least one second elastic connecting beam. The second square block is provided with a square groove for accommodating the third mass block.

7. The three-axis capacitive accelerometer according to claim 1, wherein: The first detection electrodes are provided on both sides of the first mass along the first direction and are third comb-tooth electrodes. The third comb-tooth electrodes include third movable comb teeth and third stationary comb teeth that are alternately arranged in sequence. When detecting the first acceleration, the third movable comb teeth move along with the first mass along the first direction, and a third overlapping area between the third movable comb teeth and the third stationary comb teeth changes. The second detection electrode is arranged on both sides of the second mass block along the second direction and is a fourth comb tooth electrode. The fourth comb tooth electrode includes fourth movable comb teeth and fourth static comb teeth that are alternately arranged in sequence. When detecting the second acceleration, the fourth movable comb teeth move along the second direction with the second mass block, and the fourth overlapping area between the fourth movable comb teeth and the fourth static comb teeth changes.

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