A multi-diaphragm composite capacitive pressure sensor

Abstract

The application discloses a multi-diaphragm composite capacitive pressure sensor and relates to the technical field of vacuum measurement.The multi-diaphragm composite capacitive pressure sensor comprises a cavity structure, a plurality of diaphragm mounting portions are arranged on the cavity structure, a plurality of elastic diaphragms are fixedly arranged at the diaphragm mounting portions, the structural parameters of the plurality of elastic diaphragms are different from each other, an electrode structure is arranged in the cavity structure, is located at opposite sides of the plurality of elastic diaphragms, and forms a plurality of capacitive detection gaps between the electrode structure and each elastic diaphragm, so that the electrode structure and each elastic diaphragm respectively form independent capacitive detection units, and the plurality of elastic diaphragms correspond to different deformation intervals respectively.The wide-range pressure measurement is realized in a single sensor, and meanwhile, the high-precision and high-sensitivity vacuum gas pressure measurement is ensured.

Description

Technical Field

[0001] This invention relates to the field of vacuum measurement technology, and in particular to a multi-diaphragm composite capacitive pressure sensor. Background Technology

[0002] In fields such as vacuum processing, semiconductor manufacturing, precision thin film deposition, and high-end process control, real-time and accurate monitoring of gas or vapor pressure is crucial for ensuring process stability, repeatability, and product consistency. As advanced manufacturing technologies advance towards higher purity, lower pressure, and greater vacuum, more stringent requirements are placed on pressure detection equipment in terms of sensitivity, stability, and measurement range coverage. Especially in processes involving extremely low-pressure environments, traditional pressure detection methods are finding it increasingly difficult to provide both high resolution and high accuracy monitoring capabilities across a wide pressure range.

[0003] Currently, commonly used capacitive pressure sensors typically consist of a single elastic diaphragm and a corresponding fixed electrode, forming a capacitance measurement structure. This type of structure exhibits good sensitivity and resolution within a specific pressure range, but its sensitivity is highly dependent on the mechanical parameters of the diaphragm, thus maintaining high accuracy only within a limited range. When the pressure deviates from this design range, the diaphragm deformation tends to be too large or too small, causing the capacitance change to become non-linear or insufficient for effective detection, resulting in a significant decrease in accuracy. Furthermore, to accommodate monitoring needs across different pressure ranges, existing systems often achieve wide-range measurement by connecting or combining multiple pressure sensors with different ranges in parallel. However, this leads to increased equipment size, installation complexity, higher costs, and limited accuracy when switching signals between sensors.

[0004] Therefore, how to achieve wide-range pressure measurement within a single sensor while ensuring high accuracy and high sensitivity has become a technical problem that is difficult to solve with existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-diaphragm composite capacitive pressure sensor and transmission device to solve the technical problem of how to achieve wide-range pressure measurement in a single sensor while ensuring high accuracy and high sensitivity.

[0006] To achieve the above objectives, embodiments of the present invention provide a multi-diaphragm composite capacitive pressure sensor, comprising:

[0007] A cavity structure, wherein multiple diaphragm mounting portions are provided on the cavity structure; Multiple elastic diaphragms are respectively fixedly installed at the diaphragm mounting part, and the structural parameters of the multiple elastic diaphragms are different from each other; An electrode structure is disposed within the cavity structure, located on opposite sides of the plurality of elastic diaphragms, and forms a plurality of capacitance detection gaps between the electrode structure and each elastic diaphragm, such that the electrode structure and each elastic diaphragm constitute an independent capacitance detection unit. The cavity structure and the multiple elastic diaphragms together form a measurement chamber. The first side of the multiple elastic diaphragms faces the measurement chamber, and the second side faces the reference pressure environment. The position of the electrode structure relative to the multiple elastic diaphragms is fixed, and the multiple elastic diaphragms correspond to different deformation ranges.

[0008] Furthermore, the structural parameters of each of the elastic diaphragms include at least one of the following: material, shape, size specifications, or pre-tightening method.

[0009] Furthermore, the cross-section of the cavity structure is circular, and the plurality of elastic diaphragms include a circular diaphragm disposed in the middle of the cavity structure, and a plurality of non-circular diaphragms arranged around the circular diaphragm.

[0010] Furthermore, the thickness of the circular diaphragm is greater than the thickness of each of the non-circular diaphragms.

[0011] Furthermore, the non-circular diaphragm is a fan-shaped diaphragm, each of which has a different outer radius and is arranged circumferentially along the outer edge of the circular diaphragm.

[0012] Furthermore, the non-circular diaphragm is an annular diaphragm, and multiple annular diaphragms have different diameters and are concentrically fitted around the outside of the circular diaphragm.

[0013] Furthermore, the cross-section of the cavity structure is circular, and the plurality of elastic diaphragms include a plurality of circular diaphragms disposed within the cavity structure, wherein the diameters of the plurality of circular diaphragms are different from each other, and the thicknesses of the plurality of circular diaphragms are different from each other.

[0014] Furthermore, the cross-section of the cavity structure is circular; the plurality of elastic diaphragms include a plurality of fan-shaped diaphragms distributed circumferentially, and the outer radii of the plurality of fan-shaped diaphragms are different from each other.

[0015] Furthermore, the cross-section of the cavity structure is rectangular, and the plurality of elastic diaphragms include a plurality of rectangular diaphragms of different sizes.

[0016] Furthermore, the cavity structure is provided with a gas inlet for introducing the measuring gas into the measuring chamber.

[0017] The beneficial effects of the multi-diaphragm composite capacitive pressure sensor provided by this invention are as follows: This multi-diaphragm composite capacitive pressure sensor integrates multiple elastic diaphragms with different structural parameters within the same cavity structure, and makes them, along with the same electrode structure, form independent and parallel capacitive detection units. This creates multiple continuous and overlapping deformation-capacitance response intervals within a single package. When measuring changes in chamber pressure, elastic diaphragms of different stiffness or area sequentially enter their respective linear deformation segments. The system can select the capacitive detection unit in the optimal linear interval to output a signal in real time, avoiding nonlinear errors introduced by any diaphragm due to excessive bending. Furthermore, without reducing the accuracy of vacuum measurement, the range of a single sensor unit is simultaneously extended to both high and low pressure ends. Wide-range detection can be achieved without relying on the combination of multiple vacuum gauges with different ranges, significantly simplifying the overall implementation process of wide-range vacuum measurement and reducing the structural complexity of the measuring device. Meanwhile, since all elastic diaphragms share the same electrode structure and are integrated into the same cavity, the sensitivity loss caused by interface, pipeline and signal switching when multiple devices are combined is eliminated, which significantly improves the test sensitivity in the wide range vacuum measurement process. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a multi-diaphragm composite capacitive pressure sensor according to the present invention; Figure 2 This is a schematic diagram of the combined structure of a circular diaphragm and a fan-shaped diaphragm according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the combined structure of a circular diaphragm and an annular diaphragm according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the combined structure of the fan-shaped diaphragm according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the combined structure of the circular diaphragm according to an embodiment of the present invention; Figure 6 These are schematic diagrams illustrating different combinations of polygonal diaphragms in embodiments of the present invention; Figure 7 This is a schematic diagram of the combined structure of a circular diaphragm and a polygonal diaphragm according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the combined structure of the rectangular diaphragm according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the combined structure of a rectangular diaphragm and a polygonal diaphragm according to an embodiment of the present invention.

[0019] Reference numerals: 1. Cavity structure; 11. Diaphragm mounting part; 12. Measuring chamber; 13. Reference chamber; 2. Elastic diaphragm; 21. Circular diaphragm; 22. Annular diaphragm; 23. Fan-shaped diaphragm; 24. Rectangular diaphragm; 3. Electrode structure. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0021] Currently, existing capacitive pressure sensors rely on the capacitance change formed between a diaphragm and an electrode structure 3. Specifically, the diaphragm has an electrode structure 3 covering or forming one side, while a fixed electrode structure 3 opposite the diaphragm is spaced apart, thus forming a detectable capacitance between them. When a difference occurs between the measured pressure (Px) on one side of the diaphragm and the reference pressure (Pr) on the other side, the diaphragm undergoes bending deformation. This bending directly causes a change in the distance between the diaphragm electrode and the fixed electrode, thereby changing the capacitance value with the pressure difference. In a typical embodiment, the reference pressure (Pr) on the other side of the diaphragm can be atmospheric pressure, a set fixed pressure, or a vacuum state, thereby calculating the gas or vapor pressure (Px) on the diaphragm measuring side by means of the measured capacitance change. In this way, the pressure measurement problem can be transformed into a capacitance measurement problem, achieving high-precision detection of pressures over a wide range.

[0022] However, existing capacitive pressure sensors typically employ a capacitive structure consisting of a single elastic diaphragm 2 and fixed electrodes. One side of the diaphragm bears the measurement pressure, while the other side maintains a reference pressure. Pressure measurement is achieved through the capacitance change caused by the bending of the diaphragm. This type of structure is simple in design and intuitive in measurement, but it has the following limitations: a single diaphragm structure has high measurement accuracy within a certain range, but when the pressure exceeds this range, the nonlinear bending of the diaphragm leads to a decrease in measurement accuracy; to expand the measurement range, existing technologies usually combine multiple sensors with different ranges to achieve wide-range measurement. However, combining multiple devices increases the overall structural complexity, system cost, and overall measurement sensitivity; moreover, in extremely low pressure or vacuum environments, a single diaphragm design cannot simultaneously achieve wide range and high sensitivity, failing to meet the requirements of modern high-precision vacuum measurement.

[0023] Based on this, the following is in conjunction with the appendix Figure 1 - Appendix Figure 9 The specific embodiments of the present invention will be further described in detail below.

[0024] Reference Figures 1-3 In some embodiments of the present invention, a multi-diaphragm composite capacitive pressure sensor can provide high-precision pressure measurement over a wide range, and is particularly suitable for vacuum measurement and precise pressure monitoring in extremely low pressure environments.

[0025] A multi-diaphragm composite capacitive pressure sensor has a housing enclosed by a cavity structure 1. The cavity structure 1 is divided into a measurement chamber 12 and a reference chamber 13, which are isolated from each other. The measurement chamber 12 is connected to the external pipeline to be measured through a gas inlet reserved on the cavity structure 1, while the reference chamber 13 maintains a constant reference pressure. Several diaphragm mounting parts 11 are stamped from top to bottom along the thickness direction on the top wall of the cavity structure 1. Each diaphragm mounting part 11 is an opening that penetrates the cavity wall, and an annular welded step is machined around the periphery of the opening. The peripheries of multiple elastic diaphragms 2 are fully welded to the annular welded step, thereby completely sealing the opening, so that the first side of each elastic diaphragm 2 faces the measurement chamber 12 and the second side faces the reference chamber 13. All elastic diaphragms 2 share a single electrode structure 3: This electrode structure 3 is suspended in the central axis region of the cavity structure 1 by an insulating support column and is parallel and spaced apart from each elastic diaphragm 2, thereby forming a capacitance detection gap between each elastic diaphragm 2 and the electrode structure 3; Once the position of the electrode structure 3 relative to the cavity structure 1 is set, it is locked, so the static spacing of all capacitance detection gaps only changes with the bending deformation of the corresponding diaphragm, thus making each elastic diaphragm 2 and the electrode structure 3 constitute an independent capacitance detection unit.

[0026] In some embodiments of the present invention, the structural parameters of the elastic diaphragm 2, including but not limited to material, shape, size specifications, or pre-tightening method, determine its bending deformation level under pressure. Elastic diaphragms 2 with different structural parameters exhibit different bending deformations under the same pressure; and the ease with which each elastic diaphragm 2 undergoes bending deformation under pressure can be precisely defined through a preset structural design, and the ease with which the resulting capacitance value changes can also be determined in advance through preliminary experiments or simulation calculations. Based on the above characteristics, the effective pressure measurement range corresponding to each elastic diaphragm 2 can be obtained through analysis and calculation, and this effective pressure measurement range can be converted into the corresponding capacitance value change range. When the capacitance value detected by the measuring circuit is within the capacitance value change range of a certain diaphragm, the measurement result corresponding to that diaphragm is deemed applicable; when the detected capacitance value exceeds the capacitance value change range of that diaphragm, the measurement result corresponding to that elastic diaphragm 2 is deemed inapplicable.

[0027] Reference Figures 4-9In some specific embodiments of the present invention, the horizontal cross-section of the cavity structure 1 is circular, and the plurality of diaphragm mounting portions 11 include a circular opening located at the center and a plurality of fan-shaped openings distributed at equal angles around the circular opening; correspondingly, the elastic diaphragm 2 includes a circular diaphragm 21 and a plurality of fan-shaped diaphragms 23.

[0028] In some embodiments, the thickness of the circular diaphragm 21 is significantly greater than the thickness of any of the sector-shaped diaphragms 23, and its diameter matches the step diameter of the central circular opening. The outer radii of each sector-shaped diaphragm 23 are different, causing their sector areas to increase or decrease sequentially along the circumference. The inner arcs of all sector-shaped diaphragms 23 are close to the outer periphery of the circular diaphragm 21 and are arranged at equal intervals along the circumference, thereby forming a composite diaphragm array of "central thick circle - peripheral gradient sector" in the same circumferential plane. Through the superposition of thickness and area differences, the circular diaphragm 21 corresponds to the high-pressure deformation range, and the sector-shaped diaphragms 23 correspond to the medium-pressure, low-pressure, and micro-pressure deformation ranges sequentially from the inside to the outside. When the pressure in the measuring chamber 12 decreases step by step, the circular diaphragm 21 with the largest bending stiffness enters the nonlinear segment first. At this time, the system can automatically switch to the capacitance detection unit corresponding to the sector-shaped diaphragm 23 with smaller stiffness to maintain linear output across the entire range. The arrangement of the above-mentioned elastic diaphragm combination structure can not only effectively reduce the overall structural size of the sensor, but also significantly reduce the adverse effects of pressure fluctuations in the gas being measured on the measurement results, thereby improving the accuracy of the sensor in measuring vacuum.

[0029] In other embodiments of the present invention, the thickness relationship between circular and non-circular diaphragms is not specifically limited.

[0030] In some other embodiments of the present invention, the horizontal cross-section of the cavity structure 1 remains circular, but the diaphragm mounting portion 11 is replaced with multiple concentric annular steps; the elastic diaphragm 2 is correspondingly composed of multiple annular diaphragms 22, the inner diameter, outer diameter, and thickness of which are all different, and are sequentially fitted around the periphery of the same electrode structure 3 from the inside out, forming a "multi-layer concentric ring" layout. The radial width of each annular diaphragm 22 decreases in the direction away from the center, so that the annular diaphragm 22 closer to the outside has a smaller bending stiffness, thereby corresponding to a lower pressure threshold; by adjusting the combination of the radial width and thickness of each ring, more pressure sub-intervals can be subdivided under the condition of limited radial dimensions.

[0031] In some embodiments of the present invention, the horizontal cross-section of the cavity structure 1 is changed to a rectangle, and the diaphragm mounting parts 11 are arranged in a matrix; the elastic diaphragm 2 consists of several rectangular diaphragms 24, each with different length-to-width ratios and areas, and their diagonals are aligned with the diagonal direction of the cavity structure 1, so as to make full use of the diagonal space of the rectangular cavity. The long side of each rectangular diaphragm 24 is welded to the long side wall of the cavity structure 1, and the short side is welded to the short side wall. By changing the length-to-width ratio of the rectangular diaphragms 24, significantly different bending stiffness distributions can be obtained in the same cavity plane, thereby covering a continuous range from low pressure to high pressure.

[0032] In some embodiments of the present invention, regardless of whether the cavity structure 1 adopts a circular, rectangular, or other polygonal cross-section, the electrode structure 3 remains a single conductive plate. This plate is fixedly connected to the bottom wall of the cavity structure 1 by three-point insulating support pillars. The three support points are located at the centroid of the cavity structure 1 and on two radii or diagonals symmetrical about the centroid, to ensure that the electrode structure 3 remains parallel to each elastic diaphragm 2 under temperature changes or external vibration conditions. The surface of the electrode structure 3 facing the elastic diaphragm 2 is kept mirror-finished to reduce edge electric field distortion; the surface facing away from the elastic diaphragm 2 is etched with a grid-like stress relief groove to counteract warping caused by the difference in thermal expansion coefficients between the cavity structure 1 material and the electrode material.

[0033] In some other embodiments of the present invention, in order to further extend the range without increasing the height of the cavity, a micro spacer or a wave spring can be added between the partial elastic diaphragm 2 and the electrode structure 3; the micro spacer is an insulating ceramic column, the height of which is slightly smaller than the static gap of the diaphragm when it is under zero pressure, so it only plays a limiting role when the diaphragm is excessively bent, preventing the diaphragm from being attracted to the electrode structure 3.

[0034] In some embodiments of the present invention, the measurement process is as follows: First, the capacitance value of the diaphragm with the smallest bending point is read to determine whether it falls within the applicable pressure range; if applicable, the pressure value is output; if not applicable, the measurement is switched to the diaphragm with the second smallest bending point, and the appropriate diaphragm is selected sequentially to output the measurement result. In some embodiments of the present invention, by analyzing the relationship between the bending amount and capacitance change of each diaphragm, the effective measurement range corresponding to each diaphragm can be preset. Based on the range in which the detected capacitance value is located, the most accurate pressure result is selected to achieve high-precision measurement over a wide range.

[0035] Reference Figures 4-9 In some other embodiments of the present invention, the cavity structure 1 can be a rectangular or polygonal cross-section, and the diaphragm can be a rectangular, elliptical, annular, or irregular polygon. Combinations of different cross-sections and diaphragm shapes can be flexibly selected according to actual measurement requirements.

[0036] The present invention can also be combined in various ways in terms of diaphragm material, thickness and pre-tightening method to adapt to different range, sensitivity and durability requirements and achieve multi-scenario adaptation.

[0037] In some other embodiments of the present invention, a signal processor is also included. The signal processor has a built-in capacitance-pressure calibration database for each elastic diaphragm 2 under different temperatures and pressures. By monitoring the capacitance change trends and historical data of multiple diaphragms in real time, and combining this with temperature sensor feedback, the optimal detection unit is dynamically predicted. When the pressure changes rapidly, a machine learning-based dynamic range switching algorithm is introduced, which can skip the traditional step-by-step switching mode and directly call the data of the elastic diaphragm 2 that matches the predicted pressure range, significantly improving the response speed. Simultaneously, through a periodic self-calibration mechanism, the output consistency of each elastic diaphragm 2 in overlapping pressure ranges is compared, automatically correcting drift errors caused by material creep or aging, ensuring the reliability of long-term measurements, and achieving intelligent pressure tracking.

[0038] In some other embodiments of the present invention, the machine learning-based dynamic range switching algorithm employs an incremental learning strategy, enabling multiple sensors to possess online self-optimization capabilities. In actual operation, the system continuously records the capacitance-pressure correspondence of each elastic diaphragm 2 under different operating conditions and compares it with the initial calibration data. When a drift in the response characteristics of a certain diaphragm due to long-term use is detected, the algorithm automatically initiates a local recalibration process, using cross-validation data from neighboring diaphragms to fine-tune the fitting curve of that elastic diaphragm 2. This eliminates the need for interrupted measurement or external intervention, thereby significantly extending the sensor calibration cycle and reducing maintenance costs.

[0039] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A multi-diaphragm composite capacitive pressure sensor, characterized in that, include: A cavity structure (1) is provided with a plurality of diaphragm mounting parts (11). Multiple elastic diaphragms (2) are fixedly installed at the diaphragm mounting part (11), and the structural parameters of the multiple elastic diaphragms (2) are different from each other; The electrode structure (3) is disposed in the cavity structure (1), located on the opposite side of the multiple elastic diaphragms (2), and forms multiple capacitance detection gaps between the electrode structure (3) and each elastic diaphragm (2), so that the electrode structure (3) and each elastic diaphragm (2) constitute an independent capacitance detection unit respectively. The cavity structure (1) and the multiple elastic diaphragms (2) together form a measuring chamber (12). The first side of the multiple elastic diaphragms (2) faces the measuring chamber (12) and the second side faces the reference pressure environment. The electrode structure (3) is fixed in position relative to the multiple elastic diaphragms (2). The multiple elastic diaphragms (2) correspond to different deformation ranges.

2. The multi-diaphragm composite capacitive pressure sensor according to claim 1, characterized in that, The structural parameters of each elastic diaphragm (2) include at least one of the following: material, shape, size specification or pre-tightening method.

3. The multi-diaphragm composite capacitive pressure sensor according to claim 1, characterized in that, The cavity structure (1) has a circular cross-section, and the multiple elastic diaphragms (2) include a circular diaphragm (21) disposed in the middle of the cavity structure (1), and multiple non-circular diaphragms (21) arranged around the circular diaphragm (21).

4. The multi-diaphragm composite capacitive pressure sensor according to claim 3, characterized in that, The thickness of the circular diaphragm (21) is greater than the thickness of each of the non-circular diaphragms (21).

5. A multi-diaphragm composite capacitive pressure sensor according to claim 4, characterized in that, The non-circular diaphragm (21) is a fan-shaped diaphragm (23), and the outer radii of each fan-shaped diaphragm (23) are different, and each fan-shaped diaphragm (23) is arranged circumferentially along the outer edge of the circular diaphragm (21).

6. A multi-diaphragm composite capacitive pressure sensor according to claim 3, characterized in that, The non-circular diaphragm (21) is an annular diaphragm (22). The multiple annular diaphragms (22) have different diameters and are concentrically fitted on the outside of the circular diaphragm (21).

7. A multi-diaphragm composite capacitive pressure sensor according to claim 6, characterized in that, The cavity structure (1) has a circular cross-section, and the multiple elastic diaphragms (2) include multiple circular diaphragms (21) disposed within the cavity structure (1). The diameters of the multiple circular diaphragms (21) are different from each other, and the thicknesses of the multiple circular diaphragms (21) are different from each other.

8. A multi-diaphragm composite capacitive pressure sensor according to claim 1, characterized in that, The cavity structure (1) has a circular cross-section; the multiple elastic diaphragms (2) include multiple fan-shaped diaphragms (23) distributed circumferentially, and the outer radii of the multiple fan-shaped diaphragms (23) are different from each other.

9. A multi-diaphragm composite capacitive pressure sensor according to claim 1, characterized in that, The cavity structure (1) has a rectangular cross-section, and the multiple elastic diaphragms (2) include multiple rectangular diaphragms (24) of different sizes.

10. A multi-diaphragm composite capacitive pressure sensor according to claim 4, characterized in that, The cavity structure (1) is provided with a gas inlet for introducing the measuring gas into the measuring chamber (12).

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