Capacitive micromechanical accelerometer

Abstract

The application provides a capacitive micromachined accelerometer. The capacitive micromachined accelerometer comprises a substrate with anchor points, at least one detection structure pair arranged on one side of the substrate and elastically connected to the anchor points, and a detection electrode arranged in parallel with the detection structure pair, wherein the detection structure pair comprises two seesaw structures respectively elastically connected to the substrate, the seesaw structures are asymmetric with respect to the rotation axes of the anchor points, and the asymmetric parts of the two seesaw structures are opposite and parallel; when a detection mode is detected, the sizes of the intervals formed by the two seesaw structures and the detection electrode change in opposite directions. When the accelerometer is affected by rotational angular acceleration noise, the two seesaw structures will rotate and tilt in the same direction with the corresponding anchor points as the rotation axes, which will cause common-mode changes of the differential capacitance and offset the influence, thereby reducing the influence of external rotational angular acceleration noise or external factors such as stress on the detection of the accelerometer and improving the detection precision.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of acceleration detection, and particularly relates to a capacitive micromachined accelerometer. BACKGROUND

[0002] In the related art, some micromachined accelerometers use an asymmetric seesaw structure to detect in-plane acceleration and out-of-plane acceleration. However, the acceleration detection mode in the in-plane direction and the motion mode of the angular acceleration in the out-of-plane direction coincide, and the acceleration detection mode in the out-of-plane direction and the motion mode of the angular acceleration in the in-plane direction coincide, so that the acceleration detection capability of the accelerometer with the seesaw structure is poor in resisting the influence of the corresponding direction angular acceleration of the external environment, and the accuracy of the accelerometer detection is affected. SUMMARY

[0003] The application aims to provide a capacitive micromachined accelerometer, which can reduce the influence of external rotating angular acceleration noise on the detection of the accelerometer, thereby improving the detection accuracy.

[0004] The technical scheme of the application is as follows: a capacitive micromachined accelerometer is provided, which comprises a substrate with an anchor point, at least one detection structure pair arranged on one side of the substrate and elastically connected to the anchor point, and a detection electrode arranged in parallel with the detection structure pair, the detection structure pair comprises two seesaw structures elastically connected to the substrate respectively, the seesaw structures are asymmetric with respect to the rotation shafts where the anchor points are located, and the asymmetric parts of the two seesaw structures are opposite and parallel; in the detection mode, the interval distances between the two seesaw structures and the detection electrode change in opposite directions.

[0005] The two seesaw structures are used to be connected to opposite carrier driving signals, and the acceleration detection result is obtained by analyzing the differential capacitance change between the two seesaw structures and the detection electrode and the carrier driving signal.

[0006] Further, in the initial state, the interval distances between the seesaw structures and the detection electrode are equal, and the areas of the opposite regions of the seesaw structures and the detection electrode multiplied by the distances from the centers of the opposite regions to the corresponding rotation shafts are equal.

[0007] Further, in the direction perpendicular to the extension direction of the seesaw structure, the anchor points connected by the two seesaw structures are opposite; or,

[0008] In the direction perpendicular to the extension direction of the seesaw structure, the anchor points connected by the two seesaw structures are misaligned, and the same ends of the two seesaw structures are flush.

[0009] Further, the detection electrode includes an out-of-plane electrode, which is spaced apart from the plate surface of the seesaw structure and forms a corresponding out-of-plane detection capacitance.

[0010] Further, the detection electrode includes an out-of-plane electrode, which is spaced apart from the plate surface of the seesaw structure and forms a corresponding out-of-plane detection capacitance.

[0011] The detection electrode includes two out-of-plane electrodes, which are spaced apart from the plate surface of the seesaw structure and form a corresponding out-of-plane detection capacitance, and the two out-of-plane electrodes are respectively located on two opposite sides of the corresponding rotation shaft of the same seesaw structure to form corresponding out-of-plane detection capacitances.

[0012] Further, the capacitive micromechanical accelerometer includes two detection structure pairs, the length extension direction of the seesaw structure of one detection structure pair is in a first direction, and the length extension direction of the seesaw structure of the other detection structure pair is in a second direction, and the first direction and the second direction are perpendicular to each other.

[0013] Further, the two detection structure pairs are arranged in a rectangular shape, two seesaw structures of one detection structure pair are respectively arranged on two opposite sides of the rectangular shape, and two seesaw structures of the other detection structure pair are respectively arranged on the other two opposite sides of the rectangular shape.

[0014] Further, the detection electrode includes an in-plane electrode, which is spaced apart from the side surface of the seesaw structure and forms a corresponding in-plane detection capacitance.

[0015] Further, the detection electrode includes an in-plane electrode, which is spaced apart from the side surface of the seesaw structure and forms a corresponding in-plane detection capacitance.

[0016] The detection electrode includes two in-plane electrodes, which are respectively located on two opposite sides of the same seesaw structure to form corresponding in-plane detection capacitances.

[0017] Further, the accelerometer further includes an upper cover which is spaced apart from the side of the detection structure pair away from the substrate, and the detection electrode is arranged on the substrate and / or the upper cover.

[0018] The beneficial effects of the present application are that: due to the reverse and parallel asymmetric parts of the two seesaw structures, the two seesaw structures can access two carrier driving signals with opposite phases, and when detecting the modal, the interval spacing formed by the two seesaw structures and the detection electrode changes in opposite directions, therefore, by detecting the differential capacitance change formed by the two seesaw structures and the detection electrode and combining the carrier driving signal, the corresponding direction acceleration can be further obtained, and when the same rotational angular acceleration noise of the motion modal and the detection modal affects, and the substrate is inclined due to stress and other external factors, the two seesaw structures will rotate and incline in the same direction with the corresponding anchor point as the rotation shaft, causing the common mode change of the differential capacitance to offset the influence, thereby reducing the influence of external rotational angular acceleration noise or stress and other external factors on the detection of the accelerometer, and improving the detection precision. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The structure schematic diagram (upper) and the detection modal structure schematic diagram (lower) of the capacitive micromechanical accelerometer for detecting out-of-plane acceleration of the present application;

[0020] Figure 2 The detection modal structure schematic diagram of the capacitive micromechanical accelerometer for detecting in-plane acceleration of the present application;

[0021] Figure 3 The structure schematic diagram of the capacitive micromechanical accelerometer of example one of the present application;

[0022] Figure 4 The structure schematic diagram of the capacitive micromechanical accelerometer of example two of the present application;

[0023] Figure 5 The structure schematic diagram of the capacitive micromechanical accelerometer of example three of the present application;

[0024] Figure 6 The structure schematic diagram of the capacitive micromechanical accelerometer of example four of the present application;

[0025] Figure 7 The structure schematic diagram of the capacitive micromechanical accelerometer of example five of the present application;

[0026] Figure 8 The structure schematic diagram of the capacitive micromechanical accelerometer of example six of the present application;

[0027] Figure 9 The structure schematic diagram of the capacitive micromechanical accelerometer of example seven of the present application;

[0028] Figure 10 The structure schematic diagram of the capacitive micromechanical accelerometer of example eight of the present application;

[0029] Figure 11 This is a schematic diagram of the capacitive micromechanical accelerometer of Example 9 of the present invention;

[0030] Figure 12 This is a schematic diagram of the structure of the capacitive micromechanical accelerometer of Example 10 of the present invention;

[0031] Figure 13 This is a schematic diagram of the capacitive micromechanical accelerometer of Example Eleven of the present invention;

[0032] Figure 14 This is a schematic diagram of the structure of the capacitive micromechanical accelerometer of Example Twelve of the present invention;

[0033] Figure 15 This is a schematic diagram of the structure of the capacitive micromechanical accelerometer of Example Thirteen of the present invention;

[0034] Figure 16 This is a schematic diagram of the capacitive micromechanical accelerometer of Example Fourteen of the present invention.

Detailed Implementation Methods

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] Combination Figures 1-2 A capacitive micromechanical accelerometer is provided, comprising a base 1 having an anchor point 4, at least one pair of detection structures disposed on one side of the base 1 and elastically connected to the anchor point 4, and detection electrodes 3 spaced apart from the detection structure pair. The detection structure pair includes two seesaw structures 2 elastically connected to the base 1, the seesaw structures 2 being asymmetrical with respect to the axis of rotation of their anchor point 4, and the asymmetrical portions 5 of the two seesaw structures 2 being opposite and parallel; during detection mode, the spacing between the two seesaw structures 2 and the detection electrodes 3 changes in opposite directions.

[0037] Among them, the two seesaw structures 2 are used to connect to opposite carrier drive signals respectively; the acceleration detection results are obtained by analyzing the differential capacitance change between the two seesaw structures 2 and the detection electrode 3 and the carrier drive signal.

[0038] Since the asymmetric parts 5 of the two seesaw structures 2 are opposite and parallel, the two seesaw structures 2 can be connected to two carrier driving signals with opposite phases, and when detecting the modal, the interval distances between the two seesaw structures 2 and the detection electrode 3 change in opposite directions, so by detecting the differential capacitance changes between the two seesaw structures 2 and the detection electrode 3 and combining the carrier driving signals, the corresponding acceleration in the direction can be further obtained. Moreover, when the same rotational angular acceleration noise of the motion modal and the detection modal affects the substrate 1, or when the substrate 1 is tilted due to external factors such as stress, the two seesaw structures 2 will rotate and tilt in the same direction with the corresponding anchor points 4 as the rotation shaft, causing the common-mode change of the differential capacitance to offset the influence, thereby reducing the influence of external rotational angular acceleration noise or external factors such as stress on the detection of the accelerometer, and improving the detection accuracy.

[0039] It should be understood that the rotational inertia of the two seesaw structures 2 in the plane is matched, and the rotational inertia out of the plane is matched, that is, the shapes of the two seesaw structures 2 can be the same or different; the out-of-plane rotation axis of a single seesaw structure 2 is located on the straight line between the anchor point 4 and the spring, and the in-plane motion rotation axis intersects the out-of-plane rotation axis and is perpendicular to the seesaw structure 2.

[0040] Further, in the initial state, the distances between the seesaw structures 2 and the detection electrode 3 are equal, and the areas of the opposite regions of the seesaw structures 2 and the detection electrode 3 multiplied by the distances from the centers of the opposite regions to the corresponding rotation axes are equal. In this way, the acceleration corresponding to the detection modal direction is proportional to the distance change between the seesaw structures 2 and the detection electrode 3, so by detecting the differential capacitance changes, the corresponding speed size can be further obtained.

[0041] Further, in the direction perpendicular to the extension direction of the seesaw structure 2, the anchor points 4 connected by the two seesaw structures 2 are opposite; or in the direction perpendicular to the extension direction of the seesaw structure 2, the anchor points 4 connected by the two seesaw structures 2 are staggered, and the same ends of the two seesaw structures 2 are flush, which is more space-saving. It should be understood that the positions of the corresponding anchor points 4 of the seesaw structures 2 can be set according to actual conditions. In some implementations, the anchor points 4 connected by the two seesaw structures 2 can be staggered, and the same ends of the two seesaw structures 2 can also be staggered, and the detection structure is a center-symmetric structure. In addition, the shape of the detection electrode 3 can be a rectangular flat plate, or it can be set to be bent according to actual conditions, as long as the distances between the seesaw structures 2 and the detection electrode 3 are equal in the initial state, the opposite areas of the seesaw structures 2 and the detection electrode 3 are equal, and the distances from the centers of the opposite areas of the seesaw structures 2 and the detection electrode 3 to the rotation axes of the corresponding anchor points 4 are equal.

[0042] Further, the detection electrodes 3 can include out-of-plane electrodes, which are spaced apart from the plate surfaces of the seesaw structures 2 and form corresponding out-of-plane detection capacitances. The magnitude of the out-of-plane acceleration can be further obtained by detecting the differential capacitance change of the out-of-plane detection capacitances.

[0043] Further, the detection electrodes 3 can include in-plane electrodes, which are spaced apart from the side surfaces of the seesaw structures 2 and form corresponding in-plane detection capacitances. The magnitude of the in-plane acceleration can be further obtained by detecting the differential capacitance change of the in-plane detection capacitances.

[0044] It should be understood that, for the same detection structure pair, the out-of-plane detection capacitances and the in-plane detection capacitances can be formed by the out-of-plane electrodes and the in-plane electrodes respectively, and thus the same detection structure pair can realize the detection of the out-of-plane acceleration and the detection of the in-plane acceleration.

[0045] Further, in combination with Figure 3 , 4 , 5, 6, 9, 10, 11, 12, 13 and 14, the accelerometer can include one detection structure pair, and in this case, the two seesaw structures 2 of the detection structure pair are spaced apart from each other and parallel to each other.

[0046] Further, in combination with Figure 7 , 8 , 15 and 16, the accelerometer can include two detection structure pairs, and the seesaw structures 2 of different detection structure pairs extend in different directions. When the two detection structure pairs are provided, the seesaw structures 2 of different detection structure pairs extend in directions perpendicular to each other, and thus the straight lines on which the center lines of the seesaw structures 2 of the two detection structure pairs are located intersect to form a rectangle. Specifically, the capacitive micromechanical accelerometer includes two detection structure pairs, the seesaw structures 2 of one detection structure pair extend in a first direction, and the seesaw structures 2 of the other detection structure pair extend in a second direction, and the first direction and the second direction are perpendicular to each other; preferably, the two detection structure pairs are arranged in a rectangular shape, the two seesaw structures 2 of one detection structure pair are arranged on two opposite side edges of the rectangle respectively, and the two seesaw structures 2 of the other detection structure pair are arranged on the other two opposite side edges of the rectangle respectively. Since the same detection structure pair can realize the detection of the out-of-plane acceleration and the detection of the in-plane acceleration, and the seesaw structures 2 of the two detection structure pairs extend in different directions, three-axis angular acceleration detection can be realized, and space can be saved. It should be understood that the accelerometer can also include more detection structure pairs, such as three, four, five or the like. By providing two or more detection structure pairs, the detection sensitivity can be improved.

[0047] Further, the detection electrode 3 can include one out-of-plane electrode, the out-of-plane electrode and each seesaw structure 2 form an out-of-plane detection capacitor; or the detection electrode 3 can include two out-of-plane electrodes, the out-of-plane electrodes and each seesaw structure 2 form an out-of-plane detection capacitor, and the two out-of-plane electrodes are respectively located on the two sides of the corresponding rotation shaft of the same seesaw structure 2 to form corresponding out-of-plane detection capacitors. The scheme of using two out-of-plane electrodes to realize differential detection of acceleration can further enhance the anti-interference ability and improve the detection sensitivity of the out-of-plane acceleration.

[0048] Further, the detection electrode 3 can include one out-of-plane electrode, the out-of-plane electrode and each seesaw structure 2 form an out-of-plane detection capacitor; or the detection electrode 3 can include two out-of-plane electrodes, the out-of-plane electrodes and each seesaw structure 2 form an out-of-plane detection capacitor, and the two out-of-plane electrodes are respectively located on the two sides of the corresponding rotation shaft of the same seesaw structure 2 to form corresponding out-of-plane detection capacitors. The scheme of using two out-of-plane electrodes to realize differential detection of acceleration can further enhance the anti-interference ability and improve the detection sensitivity of the out-of-plane acceleration.

[0049] Further, the accelerometer further includes an upper cover arranged on the side of the detection structure pair away from the substrate 1, and the detection electrode 3 is arranged on the substrate 1 and / or the upper cover. When the detection electrode 3 includes an out-of-plane electrode, the out-of-plane electrode can be attached to the substrate 1 and / or the upper cover, and the out-of-plane electrode is parallel to the corresponding seesaw structure 2. When the detection electrode 3 includes an in-plane electrode, the in-plane electrode can be connected to the substrate 1 and / or the upper cover perpendicularly, and the in-plane electrode is spaced apart from the side of the corresponding seesaw structure 2 to form an in-plane detection capacitor.

[0050] Based on the above-mentioned schemes of the capacitive micromechanical accelerometer, an acceleration detection method is provided, including the following steps:

[0051] Respectively input opposite carrier driving signals to the two seesaw structures 2;

[0052] Detect the differential capacitance change between the two seesaw structures 2 and the detection electrode 3;

[0053] Obtain an acceleration detection result according to the carrier driving signal and the differential capacitance change.

[0054] For out-of-plane acceleration detection, taking Z-axis out-of-plane acceleration detection as an example:

[0055] Positive carrier driving signal V p and negative carrier driving signal -V p Respectively input two seesaw structures 2 from the corresponding anchor points 4, and the acceleration a zMake two seesaw structure 2 around Y axis in opposite directions, assuming this time difference detection capacitor C1 and C2 plate opposite area is equal, the distance from the pole to the pivot distance is equal, the distance between the differential detection capacitor C1 and C2 relative change z1 and -z2 (since the accelerometer works, the angle of seesaw in a small range of changes, so the corresponding capacitor on the seesaw structure 2 dynamic plate can be approximated as a moving motion), through the design of seesaw structure 2 makes acceleration under z1 ≈ z2 = z, then have

[0056] C1 = ε * A / (d + z); C2 = ε * A / (d - z); where ε is the dielectric constant of the medium between the plates, A is the plate area, d is the initial spacing.

[0057] Because the dynamic plate of differential detection capacitor C1 and C2 is connected to the positive carrier V p and the negative carrier -V p through the anchor point 4 of the seesaw structure 2, and the out-of-plane electrode S1 (i.e. the capacitor fixed plate) is connected to the preamplifier and subsequent detection circuit with high or low resistance, we can get:

[0058] a test ∝V p *(C1-C2) = V p *ε*A(1 / (d+z)-1 / (d-z)), since z << d, 1 / (d+z)-1 / (d-z)≈-2z / d 2 .

[0059] Since z ∝ a z , the change of differential capacitor can be detected to detect the z axis acceleration.

[0060] When the accelerometer is disturbed by the rotation angle acceleration noise around the Y axis, the two seesaw structures 2 rotate in the same direction, and the distance between the differential detection capacitors C1 and C2 changes by z1' ≈ z2'. After connecting the differential carrier and capacitor detection circuit, the change is cancelled and has no effect on the output result, which can improve the detection accuracy.

[0061] When the substrate 1 (or upper cover structure) on which the detection electrode 3 is located is tilted around the Y axis due to stress or other external factors, the distance between the differential detection capacitors C1 and C2 changes by z1" ≈ z2", which can also be cancelled and has no interference on the output result, which can improve the detection accuracy.

[0062] For in-plane acceleration detection, take Y axis in-plane acceleration detection as an example:

[0063] The positive carrier drive signal V p and the negative carrier drive signal -V p are connected to the two seesaw structures 2 from the corresponding anchor points 4, and the in-plane acceleration ay The two seesaw structures 2 are rotated in opposite directions around the Z axis, and the spacing between the differential detection capacitors C1 and C2 changes relatively by y1 and -y2 (since the angle of the seesaw structure 2 during the operation of the accelerometer is in a small range, the corresponding moving electrode plate on the seesaw structure 2 can be approximated as a translational motion). By designing the seesaw structure 2, y1≈y2=y under the action of acceleration, so

[0064] C1=ε*A / (d+y); C2=ε*A / (d-y); where ε is the dielectric constant of the medium between the electrode plates, A is the electrode plate area, and d is the initial spacing.

[0065] Since the moving electrode plates of the differential detection capacitors C1 and C2 are connected to the positive carrier V p and the negative carrier -V p through the anchor points 4 of the seesaw structure 2, and the capacitor detection electrode S1 (i.e., the capacitor fixed electrode plate) is connected to the preamplifier and subsequent detection circuit with high or low resistance, the following can be obtained:

[0066] a test ∝V p *(C1-C2)=V p *ε*A(1 / (d+y)-1 / (d-y)), since y<<d, 1 / (d+y)-1 / (d-y)≈-2y / d 2 .

[0067] Since y∝a y , the change in the differential capacitor can be detected to detect the y-axis acceleration.

[0068] When disturbed by the rotation angle acceleration noise around the Z axis, the two seesaw structures 2 rotate in the same direction, and the spacing between the differential detection capacitors C1 and C2 changes by y1'≈y2'. After connecting the differential carrier and the capacitor detection circuit, the change is cancelled out and has no effect on the output result, which can improve the acceleration detection accuracy.

[0069] On the basis of the structure and detection method of the foregoing accelerometer, some specific accelerometer setting examples and corresponding acceleration detection methods are provided as follows:

[0070] Example 1:

[0071] In combination with Figure 3 , the accelerometer includes a detection structure pair and an out-of-plane electrode S1 arranged at a distance from the detection structure pair. The anchor points 4 of the two seesaw structures in the detection structure pair are flush in the direction perpendicular to the extension direction of the anchor points 4, so that the same end of the two seesaw structures is not flush, but the rotation axes under the detection mode are collinear. The out-of-plane electrode S1 is rectangular and arranged on the same side of the two anchor points 4, and the extension direction of the out-of-plane electrode S1 is perpendicular to the extension direction of the seesaw structure.

[0072] C1 = ε * A / (d + z) ; C2 = ε * A / (d - z) ;

[0073] Therefore, the acceleration a test ∝ V p *(C1-C2), so detecting the change of differential capacitance can detect the corresponding acceleration.

[0074] Example two:

[0075] In combination Figure 4 The accelerometer includes a detection structure pair and an in-plane electrode S1 arranged between the detection structure pair, the anchor points 4 corresponding to the two seesaw structure pairs in the detection structure pair are staggered in the direction perpendicular to the extension direction of the anchor points 4, and the same end of the two seesaw structures is flush, so the layout can save space, and the in-plane electrode S1 is arranged on the same side of the two anchor points 4 and is arranged in a bent manner.

[0076] C1 = ε * A / (d + z) ; C2 = ε * A / (d - z) ;

[0077] Therefore, the acceleration a test ∝ V p *(C1-C2), so detecting the change of differential capacitance can detect the corresponding acceleration.

[0078] Example three:

[0079] In combination Figure 5 On the basis of example one, the accelerometer further includes an out-of-plane electrode S2 arranged between the detection structure pair, and the in-plane electrode S1 and the out-of-plane electrode S2 are respectively located on the opposite sides of the corresponding anchor points 4.

[0080] C1 = ε * A / (d + z) ; C2 = ε * A / (d - z) ; C3 = ε * A / (d - z) ; C4 = ε * A / (d + z) ;

[0081] Therefore, the acceleration a test ∝ V p *(C1-C2)-V p *(C3-C4), the in-plane electrode S1 and the out-of-plane electrode S2 are respectively detected in a single path and then differentially detected, so that the corresponding acceleration can be detected, and the differential detection can further enhance the anti-interference ability and improve the detection sensitivity.

[0082] Example four:

[0083] In combination Figure 6On the basis of example two, the accelerometer further comprises an out-of-plane electrode S2 arranged apart from the detection structure pair, the out-of-plane electrode S1 and the out-of-plane electrode S2 are respectively located on the two sides opposite to the corresponding anchor point 4, the out-of-plane electrode S1 and the out-of-plane electrode S2 are the same in shape, and the layout of the present scheme is more space-saving.

[0084] C1 = ε * A / (d + z) ; C2 = ε * A / (d - z) ; C3 = ε * A / (d + z) ; C4 = ε * A / (d - z) ;

[0085] Therefore, a test ∝V p *(C1-C2)-V p *(C3-C4), the out-of-plane electrode S1 and the out-of-plane electrode S2 are respectively single-channel detected and then differentially detected, the corresponding acceleration can be detected, and the differential detection can further enhance the anti-interference ability and improve the detection sensitivity.

[0086] Example five:

[0087] In combination Figure 7 , the accelerometer comprises two detection structure pairs and an out-of-plane electrode S1 arranged apart from the detection structure pair, the four seesaw structures are sequentially close to each other from the head to the tail to form a rectangular ring, the out-of-plane electrode S1 has four end portions, and the four end portions respectively form corresponding out-of-plane detection capacitors with the four seesaw structures. The seesaw structures at the opposite two sides of the rectangle constitute a detection structure pair, and the out-of-plane detection capacitors formed by the same detection structure pair are located on the same side of the corresponding anchor point 4.

[0088] C1 = ε * A / (d + z) ; C2 = ε * A / (d - z) ; C3 = ε * A / (d + z) ; C4 = ε * A / (d - z) ;

[0089] Therefore, a test ∝V p *(C1-C2+C3-C4), the out-of-plane electrode S1 is single-channel detected, and the shafts are parallel and not collinear in pairs, compared with two seesaw structures, the sensitivity of acceleration detection is doubled by one more set of orthogonal seesaw structures, and the accuracy is higher.

[0090] Example six:

[0091] In combination Figure 8 , on the basis of example five, the accelerometer further comprises an out-of-plane electrode S2, and the out-of-plane electrode S2 is centrally symmetric with the out-of-plane electrode S1.

[0092] Wherein, C1=ε*A / (d+z); C2=ε*A / (d-z); C3=ε*A / (d+z); C4=ε*A / (d-z) C5=ε*A / (d-z); C6=ε*A / (d+z); C7=ε*A / (d-z); C8=ε*A / (d+z);

[0093] Therefore, a test ∝V p *(C1-C2+C3-C4)-V p *(C5-C6+C7-C8), the out-of-plane electrodes S1 and S2 are respectively single detection and then difference, and the rotation shafts are parallel to each other, which further enhances the anti-interference ability and improves the detection sensitivity (doubled), and compared with the two seesaw structures, the orthogonal seesaw structure can make the sensitivity doubled again, and the detection precision is higher.

[0094] Example seven:

[0095] In combination Figure 9 The accelerometer comprises a detection structure pair and an in-plane electrode S1 arranged at intervals with the detection structure pair, the anchor points 4 corresponding to the two seesaw structures in the detection structure pair are staggered in the direction perpendicular to the extension direction of the anchor points 4, so that the same end of the two seesaw structures is flush, and the layout is more space-saving. One end of the asymmetric part 5 of the seesaw structure extends outward to the moving electrode plate, the in-plane electrode S1 has two electrode plates and forms an in-plane detection capacitor with the moving electrode plate, respectively. It should be understood that the electrode plates of the in-plane electrode S1 are electrically connected, and the electrically connected structure can be arranged between the two seesaw structures or around the seesaw structure. The structure of the in-plane electrode S1 is not limited here.

[0096] Wherein, C1=ε*A / (d+y); C2=ε*A / (d-y);

[0097] Therefore, a test ∝V p *(C1-C2), the change of the detection difference capacitor can be detected to obtain the corresponding in-plane acceleration.

[0098] Example eight:

[0099] In combination Figure 10 On the basis of example seven, the accelerometer further comprises an in-plane electrode S2 arranged at intervals with the detection structure pair, the in-plane electrode S2 also has two electrode plates corresponding to the moving electrode plate, and the corresponding electrode plates of the in-plane electrodes S1 and S2 are arranged on the two sides of the corresponding moving electrode plate.

[0100] Wherein, C1=ε*A / (d+y); C2=ε*A / (d-y); C3=ε*A / (d-y); C4=ε*A / (d+y);

[0101] Thus, a test ∝ V p *(C1-C2), detecting the change of the differential capacitance can detect the corresponding in-plane acceleration. p *(C3-C4), the in-plane electrode S1 and the in-plane electrode S2 respectively detect single-ended and then difference to detect the corresponding in-plane acceleration, the rotation axis is parallel (Z-axis direction), and the single-ended detection and the differential detection further enhance the anti-interference ability and improve the detection sensitivity (double).

[0102] Example Nine:

[0103] In combination Figure 11 The accelerometer includes one detection structure pair and an in-plane electrode S1 arranged at the same end of the detection structure pair, the anchor points 4 of the two seesaw structure pairs in the detection structure pair are flush in the direction perpendicular to the extension direction of the anchor points 4, thus, the same end of the two seesaw structures is staggered, the same end of the seesaw structure extends outward to form a moving electrode plate, the in-plane electrode S1 has two electrode plates and forms an in-plane detection capacitance with the moving electrode plate respectively, the distance from the two in-plane detection electrodes to the corresponding anchor points 4 is equal, and the electrode wiring is closer by arranging the in-plane detection electrode S1 at the same end of the detection structure pair, and the coupling is lower.

[0104] Wherein, C1=ε*A / (d+y); C2=ε*A / (d-y);

[0105] Thus, a test ∝ V p *(C1-C2), detecting the change of the differential capacitance can detect the corresponding in-plane acceleration.

[0106] Example Ten:

[0107] In combination Figure 12 On the basis of example nine, the accelerometer further includes an in-plane electrode S2 arranged at the same end of the detection structure pair, and the in-plane electrode S2 forms an in-plane detection capacitance with the side of the moving electrode plate away from the in-plane electrode S1.

[0108] Wherein, C1=ε*A / (d+y); C2=ε*A / (d-y); C3=ε*A / (d-y); C4=ε*A / (d+y);

[0109] Thus, a test ∝ V p *(C1-C2)-V p *(C3-C4), the in-plane electrode S1 and the in-plane electrode S2 respectively detect single-ended and then difference to detect the corresponding in-plane acceleration, the rotation axis is parallel (Z-axis direction), and the single-ended detection and the differential detection further enhance the anti-interference ability and improve the detection sensitivity (double), and the electrode wiring is closer, and the coupling is lower.

[0110] Example eleven:

[0111] In combination Figure 13 On the basis of example seven, both ends of the seesaw structure are provided with dynamic plates, and the in-plane electrodes S1 and the dynamic plates form in-plane detection capacitors, thereby forming more detection sites and further improving the acceleration detection sensitivity.

[0112] C1 = ε * A / (d + y1); C2 = ε * A / (d - y1); C3 = ε * A / (d + y2); C4 = ε * A / (d - y2);

[0113] Therefore, a test ∝ V p *(C1-C2+C3-C4), detecting the change of the differential capacitor can detect the corresponding in-plane acceleration.

[0114] Example twelve:

[0115] In combination Figure 14 On the basis of example eleven, the accelerometer further comprises an in-plane electrode S2, and the side of each dynamic plate away from the in-plane electrode S2 forms a corresponding in-plane detection capacitor.

[0116] C1 = ε * A / (d + y1); C2 = ε * A / (d - y1); C3 = ε * A / (d + y2); C4 = ε * A / (d - y2); C5 = ε * A / (d - y1); C6 = ε * A / (d + y 1) ; C7 = ε * A / (d - y2); C8 = ε * A / (d + y2);

[0117] Therefore, a test ∝ V p *(C1-C2+C3-C4)-V p *(C5-C6+C7-C8), detecting the change of the differential capacitor can detect the corresponding in-plane acceleration, and the in-plane electrode S1 and the in-plane electrode S2 are respectively detected in single path and then differenced, the rotation axis is parallel (Z-axis direction), the differential detection further enhances the anti-interference ability and improves the detection sensitivity (doubled), and more detection sites further improve the acceleration detection sensitivity.

[0118] Example thirteen:

[0119] In combination Figure 15The accelerometer includes two detection structure pairs and out-of-plane electrodes SZ1, SY1, and SX1, spaced apart from each other. Four seesaw structures are arranged in a parallel, staggered ring configuration, with their ends close together. The out-of-plane electrode SZ1 has four ends, each forming a corresponding Z-axis out-of-plane differential detection capacitor with one of the four seesaw structures. The seesaw structures at opposite sides of a rectangle constitute a detection structure pair, and the out-of-plane detection capacitors formed by the same detection structure pair are located on the same side of the corresponding anchor point 4. A moving electrode plate is provided at one end of the asymmetrical portion 5 of the seesaw structure of the same detection structure pair. The in-plane electrode SY1 and the moving electrode plate of one of the detection structure pairs form a Y-axis in-plane differential detection capacitor, and the in-plane electrode SX1 and the moving electrode plate of one of the detection structure pairs form an X-axis in-plane differential detection capacitor.

[0120] Therefore, for z-axis acceleration detection:

[0121] C Z1 =ε*A Z / (d Z +z); C Z2 =ε*A Z / (d Z -z); C Z3 =ε*A Z / (d Z +z); C Z4 =ε*A Z / (d Z -z);

[0122] a Ztest ∝V p *(C Z1 -C Z2 +C Z3 -C Z4 The z-axis acceleration can be measured by detecting the change in the differential detection capacitance outside the z-axis plane.

[0123] For y-axis acceleration detection:

[0124] C Y1 =ε*A Y / (d Y +y); C Y2 =ε*A Y / (d Y -y);

[0125] a Ytest ∝V p *(C Y1 -C Y2 The z-axis acceleration can be measured by detecting the change in the differential detection capacitance outside the y-axis plane.

[0126] For x-axis acceleration detection:

[0127] C X1 =ε*A X / (d X +x); C X2 =ε*A X / (d X -x);

[0128] a Xtest ∝V p *(C X1 -C X2 The z-axis acceleration can be measured by detecting the change in the out-of-plane differential detection capacitance along the x-axis.

[0129] Moreover, through the implementation of this scheme, when the accelerometer is interfered with by external rotational angular acceleration noise, the differential detection capacitor can generate common-mode changes to cancel the influence regardless of the direction of acceleration detection, thereby reducing the impact of noise. In addition, when the substrate (or top cover, etc.) where the out-of-plane detection electrode is located tilts due to external stress or other factors, the Z-axis out-of-plane differential detection capacitor will generate common-mode changes to cancel the influence, thereby reducing the impact of external stress on Z-axis acceleration.

[0130] Example Fourteen:

[0131] Combination Figure 16 Based on Example 13, the accelerometer also includes an out-of-plane electrode SZ2, an in-plane electrode SY2, and an in-plane electrode SX2. The out-of-plane electrode SZ2 and the out-of-plane electrode SZ1 are centrally symmetrical. The in-plane electrode SY2 and the in-plane electrode SY1 form Y-axis in-plane detection capacitors on both sides of the corresponding moving electrode plate. The in-plane electrode SX2 and the in-plane electrode SX1 form X-axis in-plane detection capacitors on both sides of the corresponding moving electrode plate.

[0132] Therefore, for z-axis acceleration detection:

[0133] C Z1 =ε*A Z / (d Z +z); C Z2 =ε* AZ / (d Z -z); C Z3 =ε*A Z / (d Z +z); C Z4 =ε*A Z / (d Z -z);

[0134] C Z5 =ε*A Z / (d Z -z); C Z6= ε * A Z / (d Z +z) ; C Z7 = ε * A Z / (d Z -z) ; C Z8 = ε * A Z / (d Z +z) ;

[0135] a Ztest ∝ V p *(C Z1 -C Z2 +C Z3 -C Z4 )- V p *(C Z5 -C Z6 +C Z7 -C Z8 ), the out-of-plane electrodes SZ1 and SZ2 are respectively detected by single channel and then difference to detect the out-of-plane acceleration of Z axis.

[0136] For y-axis acceleration detection:

[0137] C Y1 = ε * A Y / (d Y +y) ; C Y2 = ε * A Y / (d Y -y) ;

[0138] C Y3 = ε * A Y / (d Y -y) ; C Y4 = ε * A Y / (d Y +y) ;

[0139] a Ytest ∝ V p *(C Y1 -C Y2 )- V p *(C Y3 -C Y4 ), the in-plane electrodes SY1 and SY2 are respectively detected by single channel and then difference to detect the in-plane acceleration of Y axis.

[0140] For x-axis acceleration detection:

[0141] C X1 = ε * A X / (d X +x) ; C X2 = ε * A X / (d X -y) ;x);

[0142] C X3 = ε * A X / (d X x); C X4 = ε * A X / (d X +x);

[0143] a Xtest ∝ V p *(C X1 -C X2 )- V p *(C X3 -C X4 ), the in-plane electrodes SX1 and the in-plane electrodes SX2 are respectively detected in single mode and then are differentially detected to detect the Y-axis in-plane acceleration.

[0144] The scheme further enhances the anti-interference capability and improves the detection sensitivity (doubled) of the differential detection of each axis on the basis of Example XIII.

[0145] It should be understood that in each of the foregoing test examples, the acceleration and the corresponding differential capacitance change amount are proportional, and thus only the detected differential capacitance change amount needs to be multiplied by the corresponding coefficient, which can be obtained through calibration tests and the like according to the corresponding implementation.

[0146] The above only describes the implementation of the present application, and it should be noted that, for those skilled in the art, improvements can be made without departing from the inventive concept, but these are all within the protection scope of the present application.

Claims

1. A capacitive micromachined accelerometer, characterized by The capacitive micromechanical accelerometer comprises a substrate with an anchor point, at least one detection structure pair arranged on one side of the substrate and elastically connected to the anchor point, and a detection electrode arranged in parallel with the detection structure pair, the detection structure pair comprises two seesaw structures respectively elastically connected to the substrate, the seesaw structures are asymmetric relative to the rotation axis of the anchor point, and the asymmetric parts of the two seesaw structures are opposite and parallel; when detecting the mode, the two seesaw structures respectively form a gap with the detection electrode, and the size of the gap changes in opposite directions. The two seesaw structures are used to respectively access opposite carrier driving signals; and the acceleration detection result is obtained by analyzing the differential capacitance change between the two seesaw structures and the detection electrode and the carrier driving signal. The detection electrode comprises at least one out-of-plane electrode, the plate surfaces of the two seesaw structures of one detection structure pair share the same out-of-plane electrode and are respectively arranged in parallel with the same out-of-plane electrode to form out-of-plane detection capacitances.

2. The capacitive micromachined accelerometer according to claim 1, characterized in that In the initial state, the gaps between each seesaw structure and the detection electrode are equal, and the areas of the opposite regions of each seesaw structure and the detection electrode multiplied by the distances from the centers of the opposite regions to the corresponding rotation axes are equal.

3. The capacitive micromachined accelerometer according to claim 2, characterized in that In the direction perpendicular to the extension direction of the seesaw structure, the anchor points connected by the two seesaw structures are opposite; or In the direction perpendicular to the extension direction of the seesaw structure, the anchor points connected by the two seesaw structures are misaligned, and the same ends of the two seesaw structures are flush. The detection electrode comprises one out-of-plane electrode, and the out-of-plane electrode and each seesaw structure form an out-of-plane detection capacitance; or 4. The capacitive micromachined accelerometer according to claim 1, characterized in that The detection electrode comprises two out-of-plane electrodes, and the out-of-plane electrodes and each seesaw structure form an out-of-plane detection capacitance, and the two out-of-plane electrodes form corresponding out-of-plane detection capacitances on the two sides of the corresponding rotation axis of the same seesaw structure. The capacitive micromechanical accelerometer comprises two detection structure pairs, the length extension directions of the seesaw structures of one detection structure pair are in a first direction, the length extension directions of the seesaw structures of the other detection structure pair are in a second direction, and the first direction and the second direction are perpendicular to each other.

5. The capacitive micromachined accelerometer according to claim 4, characterized in that The two detection structure pairs are arranged in a rectangular shape, the two seesaw structures of one detection structure pair are arranged on the opposite two sides of the rectangle, and the two seesaw structures of the other detection structure pair are arranged on the other opposite two sides of the rectangle.

6. The capacitive micromachined accelerometer according to claim 5, characterized in that The detection electrode comprises an in-plane electrode, and the in-plane electrode and the side surfaces of the seesaw structures are arranged in parallel to form corresponding in-plane detection capacitances.

7. A capacitive micromachined accelerometer according to any of claims 1-6, characterized in that, The detection electrode comprises one in-plane electrode, and the in-plane electrode and each seesaw structure form an in-plane detection capacitance; or 8. The capacitive micromachined accelerometer according to claim 7, characterized in that The detection electrode comprises two in-plane electrodes, and the in-plane electrodes and each seesaw structure form an in-plane detection capacitance, and the two in-plane electrodes are respectively located on the opposite two sides of the same seesaw structure to form corresponding in-plane detection capacitances. The accelerometer further comprises an upper cover arranged in parallel with the detection structure pair on the side away from the substrate, and the detection electrode is arranged on the substrate and / or the upper cover.

9. The capacitive micromachined accelerometer according to claim 7, characterized in that ​

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