An in-plane gyroscope with suspended electrodes

Abstract

This invention belongs to the field of micro inertial measurement sensor technology and discloses an in-plane gyroscope with suspended electrodes. The driving electrode mass block is movably connected to the driving electrode anchor point through a sensitive torsional elastic beam. The driving electrode anchor point is fixed on the substrate, and the driving electrode mass block is integrally connected to the driving mass block through edge insulation connection, suspending above the substrate. The driving mass block remains stationary during the driving mode. The sensitive mass block is divided into a left sensitive mass block and a right sensitive mass block, which are movably connected to the driving mass block through driving elastic beams. The left and right sensitive mass blocks move in the driving direction. When the sensitive angular velocity is input along the sensitive direction, the left and right sensitive mass blocks move in opposite directions along the out-of-plane normal, and the sensitive direction is perpendicular to the driving direction.

Description

Technical Field

[0001] This invention belongs to the field of micro inertial measurement sensor technology and relates to an in-plane gyroscope with suspended electrodes. Background Technology

[0002] A gyroscope is a measuring device that detects angular velocity or angle. Micro-mechanical gyroscopes, manufactured using microelectromechanical systems (MEMS) technology, offer advantages such as small size, light weight, low power consumption, strong overload resistance, and suitability for harsh environments. Primarily made of silicon, they possess excellent mechanical properties. Based on the Coriolis effect, when an object of mass *m* has a velocity *v*, and the coordinate system rotates at an angular velocity, the Coriolis force acts on the object along a detection direction orthogonal to both the direction of motion and the direction of angular velocity. By sensing the relative displacement between the sensing electrodes and processing this information through external circuitry, the object's angular velocity is obtained. The mechanical structure of a micro-gyroscope operates in two modes: a driving mode that maintains the oscillation of the driving mass and a detection mode that detects angular velocity. Based on the relationship between the direction of the driving mass's motion and the direction of the sensitive angular velocity, there are two types of gyroscopes: out-of-plane gyroscopes (also known as z-axis gyroscopes) and in-plane gyroscopes (also known as X-axis gyroscopes). Out-of-plane gyroscopes typically have their sensitive angular velocity along the normal to the sensitive structure; the structure's motion within the plane is sufficient for both driving and detection. In-plane gyroscopes, the direction of the sensitive angular velocity is usually input along a direction orthogonal to the driving direction on the sensitive structure. The sensitive mass is subjected to Coriolis force, causing it to vibrate or oscillate up and down along the normal to the sensitive structure. Detection is usually achieved through out-of-plane electrodes; therefore, the detection process of in-plane gyroscopes often significantly disturbs the driving process.

[0003] In 2011, Qualcomm proposed an out-of-plane micro gyroscope (micromechanical piezoelectric X-axis gyroscope, CN102959405B) that uses the piezoelectric effect for driving detection. This design presents a different implementation method. However, this design also suffers from the problem of the detection process affecting the driving process.

[0004] In 2021, the National University of Defense Technology proposed an in-plane sensitive axis micromechanical gyroscope (CN113532408) based on a lever structure. Its design idea is to decouple the driving and detection processes through multiple lever-type decoupling units and a complex mechanical structure. The signal-to-noise ratio of the in-plane sensitive axis micromechanical gyroscope is improved by lever amplification. However, the design is complex and the elastic beam with multiple levers has high requirements for manufacturing process. Summary of the Invention

[0005] This invention reduces structural complexity by fixing the driving mass block to the frame structure with edge-insulated connections, allowing multiple electrodes to exist in the same fixed structure. Since the driving electrode mass block is a suspended structure, the in-plane gyroscope is less disturbed when sensitive to gyroscope signals, thus giving the gyroscope better robustness.

[0006] An in-plane gyroscope with suspended electrodes, wherein the gyroscope structure has the following connection relationship:

[0007] The driving electrode mass block 15 is suspended above the substrate layer 21 and located at the top of the gyroscope structure; the middle part of the driving electrode mass block 15 is connected to the driving electrode anchor point 8 through the sensitive torsional elastic beam 11, and the driving electrode anchor point 8 is fixed on the substrate layer 21; the left and right sides of the driving electrode mass block 15 are fixedly connected to the two upper driving mass blocks 18 as one unit through edge insulating connection 5.

[0008] The driving detection mass block 14 is suspended above the substrate layer 21 and located at the bottom of the gyroscope structure; the middle part of the driving detection mass block 14 is connected to the driving detection electrode anchor point 7 through the sensitive torsional elastic beam 11, and the driving detection electrode anchor point 7 is fixed on the substrate layer 21; the left and right sides of the driving detection mass block 14 are fixedly connected to the two lower driving mass blocks 18 as one unit through the edge insulation connection 5.

[0009] The left sensitive mass block 10 and the right sensitive mass block 9 are connected to the upper driving mass block 18 and the lower driving mass block 18 respectively through two driving elastic beams 12 on their upper and lower sides.

[0010] A mass block anchor point 3 is provided on both the left and right sides of the driving electrode anchor point 8 and the driving detection electrode anchor point 7.

[0011] Each mass block anchor point 3 is connected to a driving mass block 18 via a sensitive elastic beam 6;

[0012] The drive comb pair 16 is positioned between the left sensitive mass block 10, the right sensitive mass block 9, and the drive electrode mass block 15;

[0013] The drive detection comb pair 17 is positioned between the left sensitive mass block 10, the right sensitive mass block 9, and the drive detection mass block 14;

[0014] The left sensitive electrode anchor point 1 and the right sensitive electrode anchor point 2 are fixed on the left and right sides of the gyroscope substrate, respectively.

[0015] The substrate is also provided with a left sensitive electrode 13' and a right sensitive electrode 13; the left sensitive electrode 13' is connected to the left sensitive electrode anchor point 1 through a lead; the right sensitive electrode 13 is electrically connected to the right sensitive electrode anchor point 2 through a lead.

[0016] Furthermore, the driving electrode mass block 15 is T-shaped, and the driving detection mass block 14 is inverted T-shaped, and the two are fixedly connected by a central insulating connection 4.

[0017] Furthermore, the sensitive torsional elastic beam 11 is a straight beam or an elastic folded beam; the sensitive torsional elastic beam 11 is used for the driving electrode mass block 15 and the driving detection mass block 14 to perform angular vibration along the sensitive direction;

[0018] The sensitive direction 22 is the direction of the line connecting the center of the driving electrode mass block 15 and the driving detection mass block 14.

[0019] Furthermore, the driving elastic beam 12 is a straight beam or an elastic folding beam; the driving elastic beam 12 is used for the left sensitive mass block 10 and the right sensitive mass block 9 to perform angular vibration along the sensitive direction 22.

[0020] Furthermore, the sensitive elastic beam 6 is a U-shaped beam or a serpentine beam.

[0021] Furthermore, the edge insulating connection 5 and the center insulating connection 4 are made of silicon dioxide or a combination of silicon dioxide and silicon nitride, and are formed by dry etching combined with thermal oxidation process, with a length of 1 to 500 micrometers.

[0022] Furthermore, the gyroscope is symmetrical about the direction of the line connecting the center of the driving electrode mass block 15 and the driving detection mass block 14.

[0023] Furthermore, when there is an angular velocity input along the sensitive direction, the driving electrode mass block 15, the driving mass block 18, the driving detection mass block 14, the left sensitive mass block 10, and the right sensitive mass block 9 are located in the same plane and undergo angular vibration along the sensitive direction 22.

[0024] The present invention has the following effects:

[0025] 1) The driving mass block is fixed to the frame structure with edge-insulated connections, allowing multiple electrodes to exist within the same fixed structure, reducing structural complexity. 2) The driving electrode is designed as a fixed driving electrode anchor point and a suspended driving electrode mass block. The suspended driving electrode mass block can be linked and twisted with the left and right sensitive mass blocks, minimizing the influence of the detection mode on the driving mode. 3) The in-plane gyroscope of this invention adopts a tuning fork-type dual-mass structure. The suspended driving electrode mass block acts as the stator in the driving mode motion, enabling the dual-mass structure to maintain a tuning fork-type working mode of relative motion at all times, improving the robustness of the gyroscope. Attached Figure Description

[0026] Figure 1 This is a front and side view of an in-plane gyroscope mechanical structure with electrode suspension according to the present invention.

[0027] Figure 2 This is a top view of an in-plane gyroscope with suspended electrodes according to the present invention.

[0028] Figure 3 This is a schematic diagram of the cross-section of an in-plane gyroscope with electrode suspension according to the present invention.

[0029] Figure 4 This is a schematic diagram of the operation of an in-plane gyroscope with electrode suspension according to the present invention.

[0030] In the diagram, 1-left sensitive electrode anchor point, 2-right sensitive electrode anchor point, 3-mass block anchor point, 4-center insulating connection, 5-edge insulating connection, 6-sensitive elastic beam, 7-drive detection electrode anchor point, 8-drive electrode anchor point, 9-right sensitive mass block, 10-left sensitive mass block, 11-sensitive torsional elastic beam, 12-drive elastic beam, 13'-left sensitive electrode, 13-right sensitive electrode, 14-drive detection mass block, 15-drive electrode mass block, 16-drive comb tooth pair, 17-drive detection comb tooth pair, 18-drive mass block, 19-lead hole, 20-electrode layer, 21-substrate layer, 22-sensitive direction, 23-right drive direction, 23'-left drive direction, 24-right outward direction, 24'-left outward direction, 25-structural layer Detailed Implementation

[0031] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, specific details are set forth for purposes of explanation rather than limitation, in order to help to fully understand the present invention.

[0032] It should be noted that, in order to avoid obscuring the invention with unnecessary details, only structures closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0033] Combination Figures 1 to 3 As shown, to achieve the above features, embodiments of the present invention provide an in-plane gyroscope with suspended electrodes, which can be a 3-layer structure or a 2-layer structure. If it is a 3-layer structure, it includes an electrode layer 20, a structural layer 25, and a substrate layer 21; if it is a 2-layer structure, it only includes a structural layer 25 and a substrate layer 21. The structural layer 25 is mainly made of silicon material with a thickness of 10 micrometers to 200 micrometers, and the substrate layer 21 is mainly made of silicon material or borosilicate glass material.

[0034] Combination Figures 1 to 3As shown, structural layer 25 is the main sensitive structure, with a left sensitive mass block 10 and a right sensitive mass block 9 symmetrically placed at its center. The left and right sensitive mass blocks 10 and 9 are suspended above substrate layer 22. A deep groove is pre-machined on substrate layer 21 as a structural movement gap, with a depth between 2μm and 100μm. This groove can also be machined on the surface of structural layer 25 near the substrate, serving as a similar structural movement gap. The upper and lower positions of the left and right sensitive mass blocks 10 and 9 are connected to driving mass block 18 via driving elastic beam 12. The driving elastic beam 12 is designed so that the left and right sensitive mass blocks 10 and 9 can only move relative to driving mass block 18 along the left driving direction 23' and right driving direction 23, respectively. It has high stiffness in the sensitive direction 22 and the left-outward direction 24' and right-outward direction 24. The driving elastic beam 12 is a straight beam or an elastic folding beam; the driving elastic beam 12 is used for the left and right sensitive mass blocks 10 and 9 to perform angular vibration along the sensitive direction 22.

[0035] Combination Figures 1 to 3 As shown, the driving electrode mass block 15 is suspended above the substrate layer 21 and located at the upper part of the gyroscope structure; the middle part of the driving electrode mass block 15 is connected to the driving electrode anchor point 8 through a sensitive torsional elastic beam 11, and the driving electrode anchor point 8 is fixed on the substrate layer 21; the left and right sides of the driving electrode mass block 15 are fixedly connected to the two upper driving mass blocks 18 by edge insulating connections 5. The sensitive torsional elastic beam 11 is a straight beam or an elastic folding beam. The driving detection mass block 14 is suspended above the substrate layer 21 and located at the lower part of the gyroscope structure; the middle part of the driving detection mass block 14 is connected to the driving detection electrode anchor point 7 through a sensitive torsional elastic beam 11, and the driving detection electrode anchor point 7 is fixed on the substrate layer 21; the left and right sides of the driving detection mass block 14 are fixedly connected to the two lower driving mass blocks 18 by edge insulating connections 5.

[0036] The left sensitive mass block 10 and the right sensitive mass block 9 are connected to the upper driving mass block 18 and the lower driving mass block 18 respectively through two driving elastic beams 12 on their upper and lower sides.

[0037] A mass block anchor point 3 is provided on both the left and right sides of the driving electrode anchor point 8 and the driving detection electrode anchor point 7; each mass block anchor point 3 is connected to a driving mass block 18 through a sensitive elastic beam 6, which is a U-shaped beam or a serpentine beam.

[0038] The drive comb pair 16 is disposed between the left sensitive mass block 10, the right sensitive mass block 9 and the drive electrode mass block 15; the drive detection comb pair 17 is disposed between the left sensitive mass block 10, the right sensitive mass block 9 and the drive detection mass block 14.

[0039] The left sensitive electrode anchor point 1 and the right sensitive electrode anchor point 2 are fixed on the left and right sides of the gyroscope substrate, respectively.

[0040] A left sensitive electrode 13' and a right sensitive electrode 13 are also provided on the substrate. The left sensitive electrode 13' is connected to the left sensitive electrode anchor point 1 via a lead, and the right sensitive electrode 13 is electrically connected to the right sensitive electrode anchor point 2 via a lead. The lead is usually made of metal, such as a single-layer metal film of Al or Au, or a composite metal film, or silicon material. The driving mass blocks 18 are distributed at the four corners of the structure and are fixed to the mass block anchor points 3 via sensitive elastic beams 6 distributed at the four corners of the structure. The driving mass blocks 18 are suspended above the substrate layer 21, and the mass block anchor points 3 are fixed to the substrate layer 21.

[0041] Combination Figures 1 to 4 As shown, the electrical signals of the mass block anchor point 3, drive electrode anchor point 8, drive detection electrode anchor point 7, left sensitive electrode anchor point 1, and right sensitive electrode anchor point 2 involved in this structure are directly led out through metal pads in a 2-layer example, and in a 3-layer example, the signals are led out through via 19.

[0042] Combination Figures 1 to 4 As shown, in the standby state, when an AC voltage with the structural natural frequency ω is applied to both ends of the mass block anchor point 3 and the drive electrode anchor point 8, the left sensitive mass block 10 and the right sensitive mass block 9 are forced to vibrate due to the periodically changing electrostatic force caused by the drive comb pair 16, and reach a resonance state. The left sensitive mass block 10 and the right sensitive mass block 9 will move relative to each other along the left drive direction 23' and the right drive direction 23, respectively. When there is an angular velocity input along the sensitive direction 22, the drive electrode mass block 15, the drive mass block 18, the drive detection mass block 14, the left sensitive mass block 10 and the right sensitive mass block 9 are located in the same plane and vibrate angularly along the sensitive direction 22. While the left sensitive mass block 10 and the right sensitive mass block 9 move relative to each other along the left driving direction 23' and the right driving direction 23 respectively, they vibrate along the left outward direction 24' and the right outward direction 24 respectively. As the capacitance gaps between the left sensitive mass block 10 and the right sensitive mass block 9 and the left sensitive electrode 13' and the right sensitive electrode 13 respectively change, the measurement of the input angular velocity is finally achieved.

[0043] The invention utilizes a newly designed in-plane gyroscope with suspended electrodes. The suspended electrodes reduce disturbances to the driving mode of the tuning fork gyroscope, thereby improving its robustness. This design concept and related design schemes are all protected by this patent.

Claims

1. An in-plane gyroscope with suspended electrodes, characterized in that: The connection relationships of the gyroscope structure are as follows: The driving electrode mass block (15) is suspended above the substrate layer (21) and located at the top of the gyroscope structure; the middle part of the driving electrode mass block (15) is connected to the driving electrode anchor point (8) through a sensitive torsional elastic beam (11), and the driving electrode anchor point (8) is fixed on the substrate layer (21); the left and right sides of the driving electrode mass block (15) are fixedly connected to the two upper driving mass blocks (18) through edge insulation connections (5); The driving detection mass block (14) is suspended above the substrate layer (21) and located at the bottom of the gyroscope structure; the middle part of the driving detection mass block (14) is connected to the driving detection electrode anchor point (7) through the sensitive torsional elastic beam (11), and the driving detection electrode anchor point (7) is fixed on the substrate layer (21); the left and right sides of the driving detection mass block (14) are fixedly connected to the two lower driving mass blocks (18) through edge insulation connection (5); The driving electrode mass block and the driving detection mass block are fixedly connected by a central insulating connection (4); The left sensitive mass block (10) and the right sensitive mass block (9) are connected to the upper driving mass block (18) and the lower driving mass block (18) respectively through two driving elastic beams (12); A mass block anchor point (3) is provided on both the left and right sides of the driving electrode anchor point (8) and the driving detection electrode anchor point (7); Each mass block anchor point (3) is connected to a driving mass block (18) via a sensitive elastic beam (6); The drive comb pair (16) is positioned between the left sensitive mass block (10), the right sensitive mass block (9), and the drive electrode mass block (15); The drive detection comb pair (17) is set between the left sensitive mass block (10), the right sensitive mass block (9) and the drive detection mass block (14); The left sensitive electrode anchor point (1) and the right sensitive electrode anchor point (2) are fixed on the left and right sides of the gyroscope substrate, respectively. The substrate is also provided with a left sensitive electrode (13') and a right sensitive electrode (13); the left sensitive electrode (13') is connected to the left sensitive electrode anchor point (1) by a lead wire; the right sensitive electrode (13) is electrically connected to the right sensitive electrode anchor point (2) by a lead wire.

2. The gyroscope according to claim 1, characterized in that: The driving electrode mass block (15) is T-shaped, and the driving detection mass block (14) is inverted T-shaped.

3. The gyroscope according to claim 2, characterized in that: The sensitive torsional elastic beam (11) is a straight beam or an elastic folded beam; the sensitive torsional elastic beam (11) is used for the driving electrode mass block (15) and the driving detection mass block (14) to angularly vibrate along the sensitive direction; The sensitive direction (22) is the direction of the line connecting the center of the driving electrode mass block (15) and the driving detection mass block (14).

4. The gyroscope according to claim 3, characterized in that: The driving elastic beam (12) is a straight beam or an elastic folding beam; the driving elastic beam (12) is used for the left sensitive mass block (10) and the right sensitive mass block (9) to perform angular vibration along the sensitive direction (22).

5. The gyroscope according to claim 3, characterized in that: The sensitive elastic beam (6) is a U-shaped beam or a serpentine beam.

6. The gyroscope according to claim 5, characterized in that: The edge insulating connection (5) and the center insulating connection (4) are made of silicon dioxide or a combination of silicon dioxide and silicon nitride, and are formed by dry etching combined with thermal oxidation process, with a length of 1~500 micrometers.

7. The gyroscope according to claim 6, characterized in that: The gyroscope is symmetrical about the direction of the line connecting the center of the driving electrode mass block (15) and the driving detection mass block (14).

8. The gyroscope according to claim 5, characterized in that: When there is an angular velocity input along the sensitive direction, the driving electrode mass block (15), the driving mass block (18), the driving detection mass block (14), the left sensitive mass block (10), and the right sensitive mass block (9) are located in the same plane and oscillate along the sensitive direction (22).

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