Comb tooth type capacitance acceleration sensor

Abstract

The utility model provides a comb tooth type capacitive acceleration sensor, which belongs to the technical field of acceleration sensors and comprises a substrate, a pole piece I, a pole piece II, a cantilever beam and a mass block. Cantilever beams are arranged at the two ends of the mass block, the two ends of the mass block are slidably connected with the corresponding cantilever beams in an inserted mode, and the two ends of the mass block are provided with abutting ends abutting against the corresponding cantilever beams. When the acceleration does not occur, the abutting ends at the two ends of the mass block abut against the corresponding cantilever beams at the same time. When acceleration occurs, the abutting end at one end of the mass block extrudes the corresponding cantilever beam and drives the cantilever beam to be bent, and the abutting end at the other end of the mass block is slidably separated from the corresponding cantilever beam, so that only the cantilever beam at one end is stressed and bent when the acceleration is generated, the number of the cantilever beams which are stressed and bent at the same time is reduced; and the sensitivity of the sensor is improved. Meanwhile, the cantilever beams at the two ends have a supporting effect on the mass block and are not completely separated, so that the stability of the direction of the mass block is ensured, and nonlinear errors are reduced.

Description

Technical Field

[0001] This utility model belongs to the field of acceleration sensor technology, and more specifically, relates to a comb-type capacitive acceleration sensor. Background Technology

[0002] A comb-type capacitive accelerometer utilizes numerous cross-distributed comb-shaped electrodes to form a capacitor. The comb teeth are divided into moving teeth and fixed teeth. The fixed teeth are fixed to a substrate, while the moving teeth are attached to a mass block. The mass block is mounted on the substrate via a cantilever beam. Under the action of an external force, the cantilever beam bends, causing the moving teeth on the mass block to shift relative to the fixed teeth. This changes the capacitance between the moving and fixed teeth, and the detection circuit measures the specific change in capacitance to calculate the acceleration value. For example, Chinese utility model patent CN207908539U, entitled "A Comb-Type Capacitive Triaxial MEMS Accelerometer," uses the above principle.

[0003] For existing capacitive accelerometers, the more cantilever beams there are, the more evenly the stress is distributed, ensuring the stability of the mass block's orientation and reducing nonlinear errors. However, the more cantilever beams there are, the more dispersed the stress becomes, and the less deformation of a single cantilever beam. This results in a smaller displacement of the mass block relative to the fixed teeth, and consequently, a decrease in the sensor's sensitivity. This means that reducing nonlinear errors and improving sensitivity are mutually restrictive and cannot be achieved simultaneously. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a comb-type capacitive accelerometer that reduces nonlinear errors by increasing the number of cantilever beams while maintaining sensor sensitivity.

[0005] To achieve the above objectives, the technical solution of this application provides a comb-type capacitive accelerometer, including a substrate, an electrode 1, an electrode 2, a cantilever beam, and a mass block. The electrode 1 and electrode 2 are both fixedly mounted on the substrate, and the mass block is movably mounted on the substrate via the cantilever beam. The electrode 1 has a fixed comb tooth 1, the electrode 2 has a fixed comb tooth 2, and the mass block has movable comb teeth 1 and 2 that are spaced apart from the fixed comb teeth 1 and 2, respectively. Cantilever beams are provided at both ends of the mass block, and the two ends of the mass block are slidably inserted into the corresponding cantilever beams, and both ends of the mass block have abutting ends that abut against the corresponding cantilever beams.

[0006] When acceleration occurs, the contact end of one end of the mass block presses against the corresponding cantilever beam, causing the cantilever beam to bend. The contact end of the other end of the mass block separates from the corresponding cantilever beam. This way, only one end of the cantilever beam is subjected to force and bends when acceleration occurs, reducing the number of cantilever beams bending simultaneously and improving the sensor's sensitivity. Simultaneously, since both ends of the cantilever beam support the mass block, and the contact ends of both ends do not simultaneously separate from the cantilever beams, the orientation of the mass block remains stable, reducing nonlinear errors. When no acceleration occurs, both ends of the mass block are in contact with the corresponding cantilever beams simultaneously. This ensures that when the direction of acceleration changes, at least one contact end of the mass block is in contact with the corresponding cantilever beam, avoiding linear errors caused by the simultaneous separation of both contact ends of the mass block from the corresponding cantilever beams.

[0007] Optionally, the cantilever beam has a socket, and the end of the mass block has a connector that slides into the socket. By sliding the connector in the socket, relative sliding between the mass block and the cantilever beam is achieved. When the mass block moves toward the cantilever beam away from one end, it does not cause the cantilever beam to bend; only the cantilever beam at the other end is subjected to compressive bending.

[0008] Optionally, the root of the connector has a step, which serves as an abutment end. When the mass block moves toward one of the cantilever beams, the step abuts against the cantilever beam and compresses the cantilever beam, causing it to bend.

[0009] Optionally, the socket is a blind hole, and the end of the plug part abuts against the inner end of the socket as an abutting end. When the mass block moves toward one of the cantilever beams, the end of the plug part abuts against the cantilever beam and compresses the cantilever beam to bend.

[0010] Optionally, both ends of the cantilever beam are fixedly connected to the base, and the insertion hole is located in the middle of the cantilever beam. In this way, the cantilever beam is symmetrically arranged on both sides of the mass block, which is equivalent to the support effect of four cantilever beams arranged symmetrically in a traditional way, thus ensuring the stability of the mass block.

[0011] Optionally, one end of the cantilever beam is fixedly connected to the base, and the insertion hole is located at the other end of the cantilever beam. When acceleration is generated, only a single cantilever beam bends, exhibiting extremely high sensitivity.

[0012] Optionally, each cantilever beam includes a beam body one and a beam body two fitted within the beam body one. The beam body one is made of monocrystalline silicon, and the beam body two is made of silicon oxide, with the volume of beam body two being 20% ​​to 28% of the volume of beam body one. The elastic moduli of monocrystalline silicon and silicon oxide change inversely with temperature; combining them can mutually cancel out changes in the elastic modulus of the cantilever beam caused by temperature variations, thus ensuring accuracy. The 20% to 28% volume of silicon oxide ensures that the elastic moduli of both can cancel each other out with temperature changes to an optimal state.

[0013] Optionally, a groove is provided along the extension direction of beam one, and beam two is embedded in the groove to achieve the fitting of beam one and beam two.

[0014] The advantages of the technical solution in this application compared to the prior art are as follows:

[0015] When acceleration occurs, the contact end of one end of the mass block presses against the corresponding cantilever beam, causing the cantilever beam to bend. The contact end of the other end of the mass block slides away from the corresponding cantilever beam, resulting in only one end of the cantilever beam being bent under stress. This reduces the number of cantilever beams bending simultaneously, improving the sensor's sensitivity. Simultaneously, since both cantilever beams support the mass block, and the contact ends of both cantilever beams do not simultaneously separate from them, the orientation of the mass block remains stable, reducing linearity errors. In other words, the technical solution of this application improves detection sensitivity while ensuring the orientation stability of the mass block. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of a comb-type capacitive accelerometer.

[0018] Figure 2 This is a state diagram of a comb-type capacitive accelerometer when no acceleration occurs.

[0019] Figure 3 The state diagram of the comb-type capacitive accelerometer when leftward acceleration occurs;

[0020] Figure 4 State diagram of a comb-type capacitive accelerometer when rightward acceleration occurs;

[0021] Figure 5 for Figure 3 Enlarged view of a portion of point A in the middle;

[0022] Figure 6 for Figure 3 Enlarged view of a section at point B in the middle;

[0023] Figure 7 for Figure 5 Enlarged view of section AA in the middle;

[0024] Figure 8 for Figure 4 Enlarged view of a section at point C;

[0025] Figure 9 for Figure 4 Enlarged view of a section at point D;

[0026] Figure 10 This is a schematic diagram of the second type of plug-in structure between the mass block and the cantilever beam.

[0027] Figure 11 This is a schematic diagram of the second type of comb-type capacitive accelerometer.

[0028] Icons: 1. Base; 2. Electrode 1; 3. Electrode 2; 4. Cantilever beam; 5. Mass block; 6. Fixed comb tooth 1; 7. Fixed comb tooth 2; 8. Moving comb tooth 1; 9. Moving comb tooth 2; 10. Abutment end; 11. Insertion hole; 12. Insertion part; 13. Beam body 1; 14. Beam body 2; 15. Terminal 1; 16. Terminal 2; 17. Terminal 3; 18. Slot. Detailed Implementation

[0029] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0030] Example:

[0031] This embodiment provides a comb-type capacitive accelerometer, based on... Figure 1 and Figure 2 As shown, the structure includes a base 1, electrode 2, electrode 3, cantilever beam 4, and mass block 5. Electrode 2 and electrode 3 are fixedly mounted on the base 1, while mass block 5 is movably mounted on the base 1 via cantilever beam 4. Electrode 2 has a fixed comb tooth 6, electrode 3 has a fixed comb tooth 7, and mass block 5 has movable comb teeth 8 and 9, which are spaced apart from fixed comb teeth 6 and 7, respectively. The comb-type capacitive accelerometer is fixedly mounted on the object being measured. When acceleration occurs, mass block 5 moves relative to electrode 2 and electrode 3 due to its own inertia, cantilever beam 4 bends under force, and movable comb teeth 8 and 9 move relative to fixed comb teeth 6 and 7, respectively, causing a change in capacitance between them. The magnitude of acceleration is measured by outputting a change in capacitance signal. Based on the above structure, based on... Figures 2 to 4 As shown, cantilever beams 4 are provided at both ends of the mass block 5. The two ends of the mass block 5 are slidably inserted into the corresponding cantilever beams 4, and both ends of the mass block 5 have abutting ends 10 that abut against the corresponding cantilever beams 4.

[0032] When acceleration occurs, the abutting end 10 of one end of the mass block 5 presses against the corresponding cantilever beam 4, causing the cantilever beam 4 to bend. Meanwhile, the abutting end 10 of the other end of the mass block 5 slides away from the corresponding cantilever beam 4. This ensures that only one end of the cantilever beam 4 is subjected to bending force, reducing the number of cantilever beams bending simultaneously and improving the sensor's sensitivity. Furthermore, even after the abutting end 10 of the mass block 5 separates from the corresponding cantilever beam 4, the cantilever beam 4 does not completely separate from the mass block 5, continuing to support it and ensuring the stability of the mass block 5's orientation.

[0033] When no acceleration occurs, the contact ends 10 at both ends of the mass block 5 simultaneously abut against the corresponding cantilever beams 4, preventing the contact ends 10 at both ends of the cantilever beams 4 from separating simultaneously. This ensures the stability of the mass block 5's orientation, reduces linear errors, and guarantees a smooth transition when the acceleration direction changes. Specifically, the direction of acceleration is determined by... Figure 3 The leftward movement shown becomes Figure 4 Taking the rightward movement as an example, the initial state is... Figure 3 The cantilever beam 4 on the right is bent under stress, while the cantilever beam 4 on the left is not under stress. Subsequently, the mass block 5 moves to the left due to the change in the direction of acceleration. Figure 2 The intermediate state shown, and eventually becomes Figure 4 The state shown is that the cantilever beam 4 on the left is bent under force, while the cantilever beam 4 on the right is not under force. Since the abutting ends 10 of both ends of the mass block 5 simultaneously abut against the corresponding cantilever beam 4 when the mass block 5 changes from pressing the right cantilever beam 4 to pressing the left cantilever beam 4, there will be no situation where the abutting ends 10 of both ends of the mass block 5 simultaneously separate from the corresponding cantilever beam 4.

[0034] In this embodiment, based on Figures 5 to 9 As shown, the cantilever beam 4 has a socket 11, and the end of the mass block 5 has a plug portion 12 that slides into the socket 11. The relative sliding of the mass block 5 and the cantilever beam 4 is achieved by the plug portion 12 sliding within the socket 11. When the mass block 5 moves away from one end of the cantilever beam 4, it does not cause the cantilever beam 4 to bend; only the cantilever beam 4 at the other end is subjected to pressure and bending. Regardless of whether the mass block 5 moves away from or presses against the cantilever beam 4, the plug portion 12 will not disengage from the cantilever beam 4, ensuring the cantilever beam 4 supports the mass block 5. The root of the plug portion 12 has a step, which serves as an abutment end 10. When the mass block 5 moves closer to one of the cantilever beams 4, the step abuts against that cantilever beam 4, causing it to bend, while the abutment end 10 of the other cantilever beam 4 separates from it.

[0035] As an alternative to this embodiment, based on Figure 10As shown, the insertion hole 11 can also be a blind hole. The end of the insertion part 12 serves as the abutment end 10 and abuts against the inner end of the insertion hole 11. When the mass block 5 moves toward one of the cantilever beams 4, the end of the insertion part 12 abuts against the cantilever beam 4 and compresses the cantilever beam 4 to bend, while the abutment end 10 corresponding to the other cantilever beam 4 separates from the cantilever beam 4.

[0036] Furthermore, based on Figure 3 , Figure 5 and Figure 6 As shown, both ends of the cantilever beam 4 are fixedly connected to the base 1, and the insertion hole 11 is located in the middle of the cantilever beam 4. Thus, the cantilever beam 4 is positioned on the upper and lower sides of the mass block 5. Figure 3 The arrangement (as shown in the direction) is symmetrical, which is equivalent to the support effect of four cantilever beams in a traditional symmetrical arrangement, ensuring the stability of mass block 5, and having the sensitivity equivalent to two traditional cantilever beams.

[0037] As an alternative to this embodiment, based on Figure 11 As shown, one end of the cantilever beam 4 is fixedly connected to the base 1, and the insertion hole 11 is located at the other end of the cantilever beam 4. In this way, when acceleration is generated, only a single cantilever beam 4 bends, resulting in extremely high sensitivity.

[0038] Furthermore, based on Figure 3 and Figure 5 As shown, each cantilever beam 4 includes a beam body 13 and a beam body 14 fitted into the beam body 13. Specifically, in this embodiment, a groove 18 is formed along the extension direction of the beam body 13, and the beam body 14 is embedded in the groove 18. The material of the beam body 13 is monocrystalline silicon, and the material of the beam body 14 is silicon oxide, and the volume of the beam body 14 is 20% to 28% of the volume of the beam body 13, preferably 23%. The elastic modulus of monocrystalline silicon and silicon oxide changes in opposite directions with temperature. Combining the two can cancel each other out the change in the elastic modulus of the cantilever beam 4 caused by temperature changes, thereby ensuring accuracy. The fact that silicon oxide accounts for 20% to 28% of the volume of monocrystalline silicon ensures that the elastic modulus of the two can cancel each other out to the optimal state with temperature changes.

[0039] In this embodiment, based on Figure 2 and Figure 6As shown, the edge of the base 1 has terminal 15, terminal 2 16, and terminal 3 17. Terminal 15 extends directly to electrode 2, terminal 2 16 extends directly to electrode 3, and terminal 3 17 is connected to mass block 5 via the cantilever beam 4 on the right side. Since mass block 5 and the right cantilever can slide relative to each other, a long strip contact that is always sliding and connected can be provided between the insertion part 12 and the inner wall of the insertion hole 11, and connected to terminal 3 17 via an external wire. Terminals 15, 26, and 3 17 are used to achieve communication with external circuits. The specific wiring and communication methods are existing technologies and will not be described in detail.

[0040] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A comb-type capacitive accelerometer, comprising a substrate, an electrode one, an electrode two, a cantilever beam, and a mass block, wherein the electrode one and the electrode two are fixedly mounted on the substrate, and the mass block is movably mounted on the substrate via the cantilever beam; the electrode one has a fixed comb tooth one, the electrode two has a fixed comb tooth two, and the mass block has movable comb teeth one and two, respectively spaced apart from the fixed comb teeth one and two, characterized in that: Both ends of the mass block are provided with cantilever beams, and both ends of the mass block are slidably inserted into the corresponding cantilever beams, and both ends of the mass block have abutting ends that abut against the corresponding cantilever beams. When acceleration occurs, the abutting end of one end of the mass block presses against the corresponding cantilever beam and causes the cantilever beam to bend, while the abutting end of the other end of the mass block separates from the corresponding cantilever beam; when no acceleration occurs, the abutting ends of both ends of the mass block simultaneously abut against the corresponding cantilever beam.

2. The comb-type capacitive accelerometer as described in claim 1, characterized in that: The cantilever beam has a socket, and the end of the mass block has a plug portion that slides into the socket.

3. The comb-type capacitive accelerometer as described in claim 2, characterized in that: The root of the connector has a step, which serves as the abutment end.

4. The comb-type capacitive accelerometer as described in claim 2, characterized in that: The socket is a blind socket, and the end of the plug portion serves as the abutting end, abutting against the inner end of the socket.

5. The comb-type capacitive accelerometer sensor as described in any one of claims 2-4, characterized in that: Both ends of the cantilever beam are fixedly connected to the base, and the insertion hole is located in the middle of the cantilever beam.

6. The comb-type capacitive accelerometer sensor as described in any one of claims 2-4, characterized in that: One end of the cantilever beam is fixedly connected to the base, and the insertion hole is located at the other end of the cantilever beam.

7. The comb-type capacitive accelerometer sensor as described in any one of claims 1-4, characterized in that: Each of the cantilever beams includes a beam body one and a beam body two fitted into the beam body one. The beam body one is made of monocrystalline silicon, the beam body two is made of silicon oxide, and the volume of the beam body two is 20% to 28% of the volume of the beam body one.

8. The comb-type capacitive accelerometer as described in claim 7, characterized in that: A groove is provided along the extension direction of the first beam, and the second beam is embedded in the groove.

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