Chip for biaxial quartz vibrating beam accelerometer based on four groups of resonant beams

Abstract

The invention discloses a chip for a biaxial quartz vibrating beam accelerometer based on four groups of resonant beams. The chip comprises a mounting plate, a circular mass block; the mass block and the mounting plate are connected through the four flexible supporting sheets; the second through hole is a stress isolation and wire outlet hole, and the second through hole is circular and is arranged at the central position of the mass block; and each group of resonant beams comprises two resonant beams which are oppositely arranged on the upper surface and the lower surface of the mass block, and the included angle between each resonant beam and the adjacent flexible supporting sheet is 45 degrees. The included angle between the four groups of resonant beams and the flexible supporting sheet is 45 degrees, so that the acceleration measurement in the X direction and the Y direction can be realized; because each group of resonant beams comprises an upper resonant beam and a lower resonant beam, the sensitivity of the accelerometer is improved by the differential output design of the resonant beams in different groups; when acceleration is input in any direction, the flexible supporting sheet can generate linear displacement, and the mechanical environment adaptability of the chip is effectively improved.

Description

Technical Field

[0001] The disclosed embodiments relate to the technical field of accelerometer chips, and more particularly to a chip for a dual-axis quartz resonant beam accelerometer based on four groups of resonant beams. Background Art

[0002] The quartz vibrating beam accelerometer is an accelerometer based on a MEMS (Micro-Electro-Mechanical Systems) resonant beam structure. It achieves small size, high precision, and digital output. The measurement principle of the quartz vibrating beam accelerometer is as follows: the internal resonant beam oscillates through the inverse piezoelectric effect, driven by the resonant circuit. The external input acceleration acts on the mass, converting the acceleration into force and transmitting it to the resonant beam through the flexible support. When the resonant beam senses the axial force, it generates a positive piezoelectric effect, changing the vibration frequency of the resonant beam. The change in the resonant beam frequency is proportional to the input acceleration. The resonant circuit detects the changing frequency and obtains the input information of the external accelerometer. The advantage of quartz vibrating beam accelerometers lies in their direct digital output, replacing traditional analog-to-digital conversion, minimizing the accuracy loss associated with analog-to-digital conversion. The MEMS structure of their core sensitive components facilitates miniaturization, aligning with the development trend of inertial navigation devices. Quartz vibrating beam accelerometers, with their small size, low cost, wide range, shock resistance, high accuracy, and digital output, are currently being used in high-precision inertial guidance products.

[0003] The accuracy of inertial guidance products largely depends on the precision of inertial instruments. As one of the core components of an inertial navigation system, the precision of the quartz resonant accelerometer directly determines the accuracy of the entire system's acceleration channel. With the increasing demand for combat-ready equipment, the design and process requirements for accelerometers are further tightened, necessitating improvements in the testing capabilities and environmental adaptability of quartz vibrating beam accelerometers.

[0004] Most existing quartz vibrating beam accelerometers utilize integrated single-axis quartz vibrating beam accelerometers, primarily employing a quartz resonant beam attached to a proof mass for measurement. However, these integrated quartz vibrating beam accelerometers currently only measure in one direction. A few quartz vibrating beam accelerometer technologies can measure in multiple directions, but these suffer from low scale factors, low sensitivity, and inability to overcome the effects of temperature changes on single-axis stress. This results in a degradation of the accelerometer's temperature characteristics and low measurement accuracy. In particular, under high-overload mechanical shock conditions, the accelerometers exhibit poor adaptability to the mechanical environment, failing to meet practical application requirements.

[0005] Therefore, it is necessary to improve one or more problems existing in the above-mentioned related technical solutions.

[0006] It should be noted that this section is intended to provide background or context for the technical solutions of the present disclosure stated in the claims. The description herein is not admitted to be prior art by virtue of being included in this section. Summary of the Invention

[0007] The purpose of the embodiments of the present disclosure is to provide a chip for a dual-axis quartz resonant beam accelerometer based on four sets of resonant beams, thereby overcoming one or more problems caused by the limitations and defects of related technologies to at least a certain extent.

[0008] The present disclosure provides a chip for a dual-axis quartz resonant beam accelerometer based on four sets of resonant beams, including: A mounting plate, wherein a first through hole is provided on the mounting plate; A mass block, the mass block is circular and is arranged on the first through hole of the mounting plate; Four flexible support sheets, the mass block and the mounting plate are connected by the four flexible support sheets, the four flexible support sheets are evenly distributed along the mass block, and the four flexible support sheets are located in the middle of the side of the mass block; a second through hole, the second through hole being a stress isolation and wire outlet hole, the second through hole being circular and disposed at the center of the mass block; There are four groups of resonant beams, each group of resonant beams includes two resonant beams arranged opposite to each other, one resonant beam in each group of resonant beams is arranged on the upper surface of the mass block, and the other is arranged on the lower surface of the mass block, the angle between each two adjacent groups of resonant beams is 90°, and the angle between each resonant beam and the adjacent flexible support sheet is 45°.

[0009] In one embodiment of the present disclosure, the chip also includes a plurality of resonant beam mounting grooves, and a resonant beam mounting groove is provided at both ends of each resonant beam, wherein the resonant beam mounting groove at one end is provided on the mounting plate, and the resonant beam mounting groove at the other end is provided on the mass block.

[0010] In one embodiment of the present disclosure, the resonant beam is connected to the resonant beam mounting groove by gluing.

[0011] In one embodiment of the present disclosure, the flexible support piece is a circular sector-shaped structure, and the central angle corresponding to the flexible support piece is 30°.

[0012] In one embodiment of the present disclosure, the chip further includes a mounting frame, which is disposed on the periphery of the mounting plate and is connected to the mounting plate by gluing or welding.

[0013] In one embodiment of the present disclosure, the thickness of the mounting frame is greater than the thickness of the mounting plate.

[0014] In one embodiment of the present disclosure, a plurality of resonant beam limiting grooves are formed on the mass block, and each of the resonant beams is disposed in the resonant beam limiting groove.

[0015] In one embodiment of the present disclosure, a flexible gap is provided between every two adjacent flexible support sheets.

[0016] In one embodiment of the present disclosure, the chip is made of single crystal quartz glass.

[0017] The technical solutions provided by the embodiments of the present disclosure may have the following beneficial effects: In the disclosed embodiment, a chip for a dual-axis quartz vibration beam accelerometer based on four groups of resonant beams is provided. The angle between the four groups of resonant beams and the flexible support plates is 45°, which can realize the measurement of acceleration in both X and Y directions and has a simple structure. Since each group of resonant beams has two upper and lower resonant beams, the differential output design of different groups of resonant beams improves the sensitivity of the accelerometer. The design of the four flexible support plates of the present invention allows linear displacement of the flexible support plates when acceleration is input in any direction, effectively improving the mechanical environment adaptability of the chip. The design of the circular stress isolation and wire outlet holes realizes stress isolation between the groups of resonant beams, reduces the measurement error caused by temperature drift, and the stress isolation through-holes also serve as the lead-out holes for the resonant beam wires, achieving the purpose of multiple uses of one hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0019] Figure 1 A schematic structural diagram of a chip for a dual-axis quartz vibration beam accelerometer based on four sets of resonant beams in an exemplary embodiment of the present disclosure is shown; Figure 2 Show Figure 1 Schematic diagram of the enlarged structure of part B; Figure 3 A schematic diagram of the three-dimensional structure of a chip for a dual-axis quartz vibration beam accelerometer based on four groups of resonant beams in an exemplary embodiment of the present disclosure is shown.

[0020] Reference numerals: 100, mounting plate; 200, mass block; 201, second through hole; 300, flexible support sheet; 400, resonant beam; 401, resonant beam mounting groove; 402, flexible gap; 403, resonant beam limiting groove; 500, mounting frame. DETAILED DESCRIPTION

[0021] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be embodied in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0022] In addition, the accompanying drawings are merely schematic illustrations of embodiments of the present disclosure and are not necessarily drawn to scale. Like reference numerals in the figures represent like or similar parts, and thus repeated descriptions thereof will be omitted. Some of the blocks shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically separate entities.

[0023] This example embodiment provides a dual-axis quartz beam accelerometer chip based on four sets of resonant beams, please refer to Figure 1 、 Figure 2 and Figure 3 The chip includes: a mounting plate 100 , a mass block 200 , four flexible support plates 300 and four groups of resonant beams 400 .

[0024] Specifically, the mounting plate 100 is provided with a first through-hole, on which a mass block 200 is mounted. Positioned in the exact center of the chip, the mass block 200 can convert external acceleration input into an axial force on the resonant beam 400. The circular shape of the mass block 200 increases its mass without affecting force conversion and transmission, thereby improving the sensitivity of the accelerometer.

[0025] The mass block 200 and the mounting plate 100 are connected via the four flexible support sheets 300. The four flexible support sheets 300 are evenly distributed along the mass block 200 and are located in the middle of the side of the mass block 200, that is, there is a certain spatial distance between the flexible support sheets 300 and the upper and lower surfaces of the mass block 200.

[0026] A second through hole 201 is provided at the center of the mass block 200. The second through hole 201 is a circular stress isolation and wire outlet hole for isolating stress and realizing the wire outlet function of the resonant beam 400. The diameter of the second through hole 201 can be set to 2.5 mm.

[0027] Each group of resonant beams 400 includes two resonant beams 400 disposed opposite each other. One resonant beam 400 in each group of resonant beams 400 is disposed on the upper surface of the mass block 200, and the other is disposed on the lower surface of the mass block 200. The angle between two adjacent groups of resonant beams 400 is 90°, and the angle between each resonant beam 400 and its adjacent flexible support sheet 300 is 45°. Since the chip of the present application is provided with four groups of resonant beams 400, the total number of resonant beams 400 is eight.

[0028] In this embodiment, the angle between the four groups of resonant beams 400 and the flexible support sheet 300 of the present invention is 45°, which can realize the measurement of acceleration in the X and Y directions, and has a simple structure; since each group of resonant beams 400 has two upper and lower resonant beams 400, the differential output design of different groups of resonant beams 400 improves the sensitivity of the accelerometer; the design of the four flexible support sheets 300 of the present invention is that when acceleration is input in any direction, the flexible support sheet 300 can undergo linear displacement, effectively improving the mechanical environment adaptability of the chip; the design of the circular stress isolation and wire outlet hole realizes stress isolation between each group of resonant beams 400, reduces the measurement error caused by temperature drift, and the stress isolation through hole also serves as the lead-out hole of the resonant beam wire, achieving the purpose of multiple uses of one hole.

[0029] The specific details of each structure in the above embodiments are described below.

[0030] Please refer to Figure 3 To provide sufficient space for the movement of mass 200, the thickness of the mounting frame 500 is greater than that of the mounting plate 100. Specifically, the mounting plate 100 is located in the center of the mounting frame 500 in terms of height. Besides accommodating mass 200 on the mounting plate 100, the mounting frame 500 leaves extra space for mass 200 to move. Accordingly, the total thickness of the mounting plate is 2.0 mm, while the thickness of mass 200 is 1.0 mm. This leaves 0.5 mm of free space above and below mass 200, sufficient for the movement of mass 200.

[0031] The following describes the installation of the resonant beam 400. Each resonant beam 400 is provided with a resonant beam mounting slot 401 at both ends. The resonant beam mounting slot 401 at one end is located on the mounting plate 100, while the resonant beam mounting slot 401 at the other end is located on the mass block 200. Thus, one end of the resonant beam 400 is located within the resonant beam mounting slot 401 on the mounting plate 100, then spans a flexible gap 402 (described below) between the mass block 200 and the mounting plate 100, with the remaining portion located on the mass block 200. The resonant beam mounting slot 401 can be etched into the mounting plate 100 and the mass block 200. The resonant beam 400 can be attached to the resonant beam mounting slot 401 by gluing, which reduces stress on the resonant beam 400 and reduces its damage. Each set of resonant beams 400 includes two resonant beams 400 positioned on the upper and lower surfaces of mass 200. The positions of the four resonant beams 400 coincide with either the X or Y coordinate axis. The design of two resonant beams 400 per set improves the sensitivity of the accelerometer. Compared to a single resonant beam 400 design, the accelerometer's scale factor is doubled, doubling its sensitivity. The two resonant beams in the X direction form a differential structure, enabling measurement of acceleration in the X direction; the two resonant beams in the Y direction form a differential structure, enabling measurement of acceleration in the Y direction.

[0032] The flexible support piece 300 connecting the proof mass 200 and the mounting plate 100 is shaped like a circular sector, with an inner diameter of 14.0 mm, an outer diameter of 15.0 mm, and a thickness of 0.1 mm. The width-to-thickness ratio of the flexible support piece 300 satisfies 20:1, and the corresponding central angle of the flexible support piece 300 is 30°. A flexible gap 402 is provided between adjacent flexible support pieces 300. This gap 402 effectively reduces gas damping interference while ensuring high rigidity for the flexible support piece 300. All four flexible support pieces 300 are activated when acceleration is input in any direction. The design of the four flexible support pieces 300 and the flexible gap 402 improves the accelerometer's adaptability to mechanical environments and structural stability. The flexible support piece 300 connects the mass block 200 and the mounting plate 100 to achieve the transmission of external input acceleration.

[0033] Flexible support sheet 300 is not provided in the X and Y sensitive axis directions. Instead, it is positioned at a 45° angle to the sensitive axis. Flexible gap 402 is positioned in the direction of the sensitive axis. This effectively reduces coupling errors between the X and Y axes, reduces interference during calibration, and improves measurement accuracy. Flexible gap 402 is also shaped like a circular sector, with a corresponding central angle of 60°.

[0034] To limit the position of the resonant beam 400, a plurality of resonant beam limiting grooves 403 are provided on the mass block 200, with each resonant beam 400 positioned within one of the resonant beam limiting grooves 403. The resonant beam limiting grooves 403, arranged symmetrically on the upper and lower surfaces of the mass block 200, provide a stable operating space for the vibrating resonant beam 400 by limiting the position of the resonant beam 400. This prevents the resonant beam 400 from breaking due to excessive vibration amplitude under abnormal input conditions, thereby protecting the resonant beam 400.

[0035] The circular stress isolation and wire exit hole design in this application significantly reduces interference stress in each axis and temperature stress under variable temperature. Its diameter is 2.5 mm, forming a 5.5:1 ratio with the diameter of mass block 200. Second through hole 201, on the one hand, serves as a stress isolation zone, improving the stability of the accelerometer and reducing multi-dimensional coupling errors. On the other hand, it serves as a wire exit hole for resonant beam 400, connecting to the resonant circuit and forming a pathway. The stress isolation and wire exit hole achieve a multi-purpose design goal, promoting the development of chip integration.

[0036] In addition, a mounting frame 500 is provided on the periphery of the mounting plate 100, and the mounting frame 500 is connected to the mounting plate 100 by gluing or welding. The mounting frame 500 is a rigid component connecting the chip to the outside, and can be glued or laser welded.

[0037] The overall volume of the chip of the present application can be 24mm×24mm×2mm, with symmetry between the upper and lower surfaces, realizing sensitivity to dual-axis acceleration, and achieving the goals of miniaturization and low power consumption.

[0038] The mounting plate 100 and mounting frame 500 of the present application are made of single-crystal quartz glass, and the X- and Y-direction resonant beams 400 are both made of Z-cut single-crystal quartz glass, which greatly reduces the mismatch between heterogeneous materials, reduces external interference, avoids the influence of temperature changes on single-surface stress, improves the temperature characteristics of the quartz resonant beam accelerometer, eliminates the mismatch between heterogeneous materials, and improves temperature stability.

[0039] The following describes the use of the chip of this application.

[0040] When there is an acceleration input along the X-axis, the mass block 200 drives the four flexible support plates 300 at a 45-degree angle to the coordinate axis to undergo linear displacement. The linear displacement generates an axial force along the X-axis. The two groups of resonant beams 400 located in the X-axis direction sense the input axial force. The design of the resonant beam group increases the sensitivity by 1 times compared to a single resonant beam. The frequency of one group of resonant beams 400 increases, while the frequency of the other group of resonant beams 400 decreases. The frequency of the differential change is proportional to the input acceleration, thereby realizing the measurement of acceleration in the X-axis direction.

[0041] When there is an acceleration input along the Y-axis, the mass block 200 drives the four groups of flexible support plates 300 at a 45° angle to the coordinate axis to undergo linear displacement. The linear displacement generates an axial force along the Y-axis. The two groups of resonant beams 400 located in the Y-axis direction sense the input axial force. The frequency of one group of resonant beams 400 increases, while the frequency of the other group of resonant beams 400 decreases. The frequency of the differential change is proportional to the input acceleration, thereby realizing the measurement of acceleration in the Y-axis direction.

[0042] The dual-axis quartz vibrating beam accelerometer chip based on four groups of resonant beams 400 in this application has strong adaptability to mechanical environments, high structural stability, large scale factor, simple structure, and low cost. It realizes dual-axis measurement and has a high level of miniaturization and integration. It adapts to the development trend of miniaturization, low cost, and integration of inertial instruments, improves the measurement accuracy of accelerometer sensors, and promotes the technical development of dual-axis vibrating beam accelerometers.

[0043] It should be noted that compared with the prior art, the technical innovations of this application are mainly reflected in: the application adopts four groups of resonant beams 400 crystal groups, which greatly improves the sensitivity compared with the prior art; the flexible support sheet 300 of this application is at an angle of 45 degrees to the X and Y axes respectively, while the flexible support of the prior art is at an angle of 0 degrees to the X and Y axes respectively. After numerical simulation tests, the flexible supports of 0 degrees, 30 degrees, 45 degrees, and 60 degrees are optimal when the angle with the X and Y axes is 45 degrees, which effectively reduces the dual-axis coupling and ensures higher sensitivity; the flexible support of this application is at an angle of 45 degrees to the X and Y axes, which effectively reduces the dual-axis coupling and ensures higher sensitivity. The stress isolation structure is circular and located at the center of the mass block 200. After a large number of simulation tests on circular, trapezoidal, and quadrilateral structures, the applicant found that the circular structure can most effectively reduce temperature stress interference and improve the temperature characteristics of the product. Compared with the circular ring of the prior art, the performance of the product is effectively improved; the double-sided etching of the chip resonant beam group of the present application is more difficult than the prior art process, and requires a breakthrough in the etching process to be successfully completed. The prior art cannot do this. The applicant's laboratory has made a breakthrough in the double-sided resonant beam wet etching process.

[0044] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like in the above description indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present disclosure.

[0045] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly indicate the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0046] In the embodiments of the present disclosure, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," "fixed," and the like should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present disclosure based on specific circumstances.

[0047] In the embodiments of the present disclosure, unless otherwise expressly specified and limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0048] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0049] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the appended claims.

Claims

1. A chip for a dual-axis quartz vibration beam accelerometer based on four sets of resonant beams, characterized in that: include: A mounting plate, wherein a first through hole is provided on the mounting plate; A mass block, the mass block is circular and is arranged on the first through hole of the mounting plate; Four flexible support sheets, the mass block and the mounting plate are connected by the four flexible support sheets, the four flexible support sheets are evenly distributed along the mass block, and the four flexible support sheets are located in the middle of the side of the mass block; a second through hole, the second through hole being a stress isolation and wire outlet hole, the second through hole being circular and disposed at the center of the mass block; There are four groups of resonant beams, each group of resonant beams includes two resonant beams arranged opposite to each other, one resonant beam in each group of resonant beams is arranged on the upper surface of the mass block, and the other is arranged on the lower surface of the mass block, the angle between each two adjacent groups of resonant beams is 90°, and the angle between each resonant beam and the adjacent flexible support sheet is 45°.

2. The chip for a dual-axis quartz vibration beam accelerometer based on four sets of resonant beams according to claim 1, characterized in that: The chip also includes a plurality of resonant beam mounting grooves, and each resonant beam is provided with a resonant beam mounting groove at both ends, wherein the resonant beam mounting groove at one end is provided on the mounting plate, and the resonant beam mounting groove at the other end is provided on the mass block.

3. The chip for a dual-axis quartz vibration beam accelerometer based on four sets of resonant beams according to claim 2, characterized in that: The resonant beam is connected to the resonant beam installation groove by gluing.

4. The chip for a dual-axis quartz vibration beam accelerometer based on four sets of resonant beams according to claim 1, characterized in that: The flexible support piece is a circular sector structure, and the central angle of the flexible support piece is 30°.

5. The chip for a dual-axis quartz vibration beam accelerometer based on four sets of resonant beams according to claim 1, characterized in that: The chip further includes a mounting frame, which is arranged on the periphery of the mounting plate and is connected to the mounting plate by gluing or welding.

6. The chip for a dual-axis quartz vibration beam accelerometer based on four sets of resonant beams according to claim 5, characterized in that: The thickness of the mounting frame is greater than the thickness of the mounting plate.

7. The chip for a dual-axis quartz vibration beam accelerometer based on four sets of resonant beams according to any one of claims 1 to 6, characterized in that: A plurality of resonant beam limiting grooves are provided on the mass block, and each of the resonant beams is arranged in the resonant beam limiting groove.

8. The chip for a dual-axis quartz vibration beam accelerometer based on four sets of resonant beams according to any one of claims 1 to 6, characterized in that: A flexible gap is provided between every two adjacent flexible supporting sheets.

9. The chip for a dual-axis quartz vibration beam accelerometer based on four sets of resonant beams according to any one of claims 1 to 6, characterized in that: The chip is made of single crystal quartz glass.

Images