Capacitive film pressure sensor

Abstract

The invention discloses a capacitive film pressure sensor, which belongs to the technical field of sensors and comprises a film assembly, the film assembly comprises a strain film, a first annular piece and a second annular piece, and the strain film is flatly embedded between the first annular piece and the second annular piece. The outer edge of the strain film is located in the projection area of the first ring piece and the second ring piece. According to the invention, the membrane assembly is formed by pressing the strain membrane through the two annular pieces, the strain membrane is connected with the shell through the ceramic annular pieces, the signal of the strain membrane is led out, and the strain membrane is isolated from the metal shell and other metal parts, so that the situation that the strain membrane is directly embedded into the shell to introduce noise and stray capacitance is avoided; meanwhile, the sealing performance of the vacuum pressure detection cavity is improved, and the measurement precision of the sensor is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a capacitive thin film pressure sensor. Background Art

[0002] The capacitive thin film pressure sensor uses an alloy pressure strain diaphragm as a variable electrode to form a capacitive structure with the conductive coating on the ceramic substrate, and also forms a vacuum sensing chamber of the sensor. The pressure changes on both sides of the alloy pressure strain diaphragm, thereby causing the capacitance value to change accordingly, thereby realizing the transmission of pressure changes.

[0003] In order to make the alloy pressure strain diaphragm face the ceramic base electrode in parallel and be firmly installed in the sensor structure, a common method is to use metal welding methods, such as laser welding, parallel brazing, etc. to weld the alloy strain diaphragm and the metal shell of the sensor together. This method is convenient for signal extraction at the alloy strain diaphragm end, but the capacitor, as a sensitive device, is connected to the metal shell, and the metal shell is usually connected to the test equipment, which is easy to introduce external signal noise, thereby affecting the test accuracy of the sensor.

[0004] The inner wall of the vacuum sensing chamber in the sensor is usually made of a metal material with the same thermal expansion coefficient as the alloy strain diaphragm, or a large area of ​​metal coating is sprayed on the insulating pressure-resistant material. This approach is beneficial to the stability and thermal balance of the air pressure, but it also introduces a series of parasitic capacitances, which will also affect the test performance of the sensor. The present invention proposes a new solution to the above problems. Summary of the invention

[0005] In order to overcome at least one of the above disadvantages, the present invention provides a capacitive thin film pressure sensor. The object of the present invention can be achieved by adopting the following technical solution:

[0006] A capacitive film pressure sensor comprises a diaphragm assembly, wherein the diaphragm assembly comprises a strain film, a first annular member and a second annular member, wherein the strain film is flatly embedded between the first annular member and the second annular member, and an outer edge of the strain film is located within a projection area of ​​the first annular member and the second annular member.

[0007] In one possible implementation, the diaphragm assembly is formed by sintering a strained film, a first annular member, and a second annular member, and the first annular member and the second annular member both include ceramic materials.

[0008] In one possible implementation, the outer diameter of the strain film is smaller than the outer diameter of the first annular member, and the outer diameter of the strain film is larger than the inner diameter of the first annular member;

[0009] The outer diameter of the strain film is smaller than the outer diameter of the second annular member, and the outer diameter of the strain film is larger than the inner diameter of the second annular member.

[0010] In one possible implementation manner, the capacitive film pressure sensor further includes a housing, and the diaphragm assembly is disposed in an inner cavity of the housing.

[0011] In one possible implementation manner, the first annular member is provided with a first conductive hole, and the first conductive hole is located in an edge projection area of ​​the strain film.

[0012] In one possible implementation, the capacitive film pressure sensor also includes a fixed electrode, the fixed electrode includes a ceramic substrate, the ceramic substrate is provided with a conductive coating on the first surface facing the diaphragm assembly, the ceramic substrate is provided with a circuit board on the second surface facing away from the diaphragm assembly, and the ceramic substrate is provided with a second conductive hole connected to the first conductive hole.

[0013] In one possible implementation, the capacitive film pressure sensor also includes a conductive member, which is inserted into the first conductive hole and the second conductive hole, wherein a first end of the conductive member is electrically connected to the strain film, and a second end of the conductive member is electrically connected to the circuit board.

[0014] In one possible implementation, the conductive member is connected to the fixed electrode, and the conductive member is connected to the diaphragm assembly;

[0015] The length of the conductive member is adjustable, or the connection position of the conductive member and the fixed electrode and / or the diaphragm assembly is adjustable, so as to adjust the height difference between the fixed electrode and the strain film.

[0016] In one possible implementation manner, a third conductive hole is opened on the ceramic substrate, and the third conductive hole is located in the edge projection area of ​​the conductive coating. The third conductive hole is filled with a conductive material, and the first end of the conductive material is electrically connected to the conductive coating, and the second end of the conductive material is electrically connected to the circuit board.

[0017] In one possible implementation, the circuit board includes:

[0018] A capacitance conversion module, wherein the capacitance conversion module is used to convert a capacitance signal into a voltage signal;

[0019] A wireless transmission module, wherein the wireless transmission module is electrically connected to the capacitance conversion module and is connected to an antenna for receiving the voltage signal and wirelessly transmitting the voltage signal to a terminal.

[0020] Beneficial technical effects of the present invention: According to the contents of the present disclosure, the capacitive film pressure sensor includes a diaphragm assembly formed by pressing a strain film together with two annular parts. The strain film is connected to the housing through a ceramic annular part, and the signal of the strain film is led out, and the strain film is isolated from the metal housing and other metal parts, thereby avoiding the situation where the strain film is directly embedded in the housing to introduce noise and parasitic capacitance, while improving the sealing of the vacuum pressure detection chamber, greatly improving the measurement accuracy of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In the accompanying drawings, the following are given by way of example and not limitation:

[0022] Figure 1 A schematic diagram showing the structure of the first annular member and the diaphragm assembly at an angle is shown;

[0023] Figure 2 A schematic diagram showing the structure of a fixed electrode at an angle is shown;

[0024] Figure 3 A schematic diagram showing the structure of the fixed electrode at another angle is shown;

[0025] Figure 4 A schematic diagram showing the structure of the diaphragm assembly at one angle is shown;

[0026] Figure 5 A structural cross-sectional view of a capacitive thin film pressure sensor is shown.

[0027] In the figure:

[0028] 1. Diaphragm assembly; 2. Fixed electrode; 3. Conductive member; 4. Support frame; 5. Spring; 6. Housing; 7. Pressure chamber to be measured; 8. Reference pressure chamber;

[0029] 11. strain film; 12. first annular member; 13. second annular member;

[0030] 21. Ceramic substrate; 22. Conductive coating; 23. Circuit board; 24. Antenna;

[0031] 121, first conductive hole; 211, second conductive hole; 221, third conductive hole; 231, wireless transmission module; 232, capacitance conversion module. DETAILED DESCRIPTION

[0032] In the following detailed disclosure, these embodiments are fully described with reference to the accompanying drawings. In order to make the technical scheme of the present invention more clear and specific to those skilled in the art, the implementation methods described below are not limited to this. The present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings.

[0033] In the present invention, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise clearly defined. The terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front” and “back” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, cannot be understood as a limitation on the present invention.

[0035] The present invention provides a capacitive thin film pressure sensor, such as Figure 1-Figure 5 As shown, the capacitive film pressure sensor includes a diaphragm assembly 1, which includes a strain film 11, a first annular member 12 and a second annular member 13. The strain film 11 is flatly embedded between the first annular member 12 and the second annular member 13, and the outer edge of the strain film 11 is located within the projection area of ​​the first annular member 12 and the second annular member 13.

[0036] The capacitive film pressure sensor includes a diaphragm assembly 1 formed by pressing a strain film 11 together with two annular parts. The strain film 11 is connected to the housing through a ceramic annular part, and the signal of the strain film 11 is led out, and the strain film 11 is isolated from the metal housing and other metal parts, thereby avoiding the situation where the strain film 11 is directly embedded in the housing to introduce noise and parasitic capacitance, while improving the sealing of the vacuum pressure detection chamber, and greatly improving the measurement accuracy of the sensor.

[0037] The first annular member 12 and the second annular member 13 may have the same shape and size. The cross-sectional shapes of the first annular member 12 and the second annular member 13 are both approximately an annular columnar structure. A groove for accommodating the strain film 11 may be provided on the annular column.

[0038] The shapes and sizes of the first annular member 12 and the second annular member 13 may be different, such as Figure 5 As shown, the first annular member 12 includes an annular cylinder and an annular flange extending outward, the annular flange extends toward the second annular member 13 and abuts against the second annular member 13 , and the strain film 11 is located inside the annular flange and between the first annular member 12 and the second annular member 13 .

[0039] In one possible implementation, the diaphragm assembly 1 is formed by sintering the strain film 11 , the first annular member 12 , and the second annular member 13 , and both the first annular member 12 and the second annular member 13 include ceramic materials.

[0040] The first annular member 12 and the second annular member 13 are ceramic rings formed by low-temperature sintering, and the surface of the ceramic rings is smooth. The metal strain film 11 is clamped between the two ceramic rings and solidified by high-temperature sintering at a temperature of 800°C-1100°C. The sintering forms a diaphragm assembly 1 with a ceramic structure on the outer cover and a strain film 11 in the middle. The strain film 11 is completely isolated from the housing and other metal parts by the ceramic structure. The diaphragm assembly 1 serves as a variable electrode of a capacitive film pressure sensor.

[0041] The sintering time increases gradually with the size of the ceramic ring. The specific sintering temperature and sintering time can be set according to the specific size of the ceramic ring, and can be used to solidify and clamp the strain film 11 to form a whole after sintering.

[0042] In this embodiment, the inner diameter of the ceramic ring is 5 cm, the outer diameter is 8 cm, and the diameter of the strain film 11 is 7 cm. At this time, the sintering temperature is 1000° C.-1100° C., and the sintering time is about 2 hours.

[0043] In one possible implementation, Figure 2 As shown, the outer diameter of the strain film 11 is smaller than the outer diameter of the first annular member 12 , and the outer diameter of the strain film 11 is larger than the inner diameter of the first annular member 12 ; the outer diameter of the strain film 11 is smaller than the outer diameter of the second annular member 13 , and the outer diameter of the strain film 11 is larger than the inner diameter of the second annular member 13 .

[0044] The outer edge of the strain film 11 is completely located between the first annular member 12 and the second annular member 13 along the circumferential direction, so that the strain film 11 in the middle part of the sintered and solidified diaphragm assembly 1 remains flat, thereby ensuring the accuracy of the sensor.

[0045] In one possible implementation, Figure 5 As shown, the capacitive film pressure sensor further includes a housing 6 , and the diaphragm assembly 1 is arranged in the inner cavity of the housing 6 .

[0046] Among them, Figure 5 As shown, the capacitive film pressure sensor also includes a housing 6, which usually includes a metal material. The strain film 11 in the middle part of the diaphragm assembly 1 faces the air inlet, the fixed electrode 2 is located on the side of the diaphragm assembly 1 away from the air inlet, and the strain film 11 is parallel to the fixed electrode 2.

[0047] The diaphragm assembly 1 is rigidly connected to the housing 6 , and the outer diameters of the first annular member 12 and the second annular member 13 are adapted to the inner diameter of the housing 6 .

[0048] The diaphragm assembly 1 and the inner wall of the housing 6 can be fixed by setting a sealing ring, and the sealing ring can be made of metal material or rubber material to improve the stability of the connection between the diaphragm assembly 1 and the housing 6, while improving the sealing of the reference pressure chamber 8.

[0049] Among them, Figure 5 As shown, a support frame 4 may also be provided in the housing 6 , and the support frame 4 is used to support the diaphragm assembly 1 .

[0050] Among them, Figure 5 As shown, the capacitive film pressure sensor also includes a spring 5, which is arranged in the shell 6. The first end of the spring 5 abuts against the inner wall of the shell 6, and the second end of the spring 5 abuts against the fixed electrode 2, that is, abuts against the ceramic substrate 21, and is used to apply elastic force to the fixed electrode 2 to ensure the position stability of the fixed electrode 2, that is, to ensure the position stability between the fixed electrode 2 and the strain film 11, and to ensure detection accuracy and stability.

[0051] The capacitive film pressure sensor includes an air intake duct, a strain film 11 and a fixed electrode 2. The side of the diaphragm assembly 1 facing away from the air intake duct is a reference pressure chamber 8, the side of the diaphragm assembly 1 facing away from the fixed electrode 2 is a pressure chamber to be measured 7, and the strain film 11 is located between the pressure chamber to be measured 7 and the reference pressure chamber 8.

[0052] It can be understood that the air inlet pipe is connected to the pressure chamber 7 to be measured, one side of the strain film 11 is the pressure chamber 7 to be measured, and the other side of the strain film 11 is the reference pressure chamber 8. The two chambers are relatively independent, and there is a pressure difference between the two chambers. The pressure fluctuation of the pressure chamber 7 to be measured causes the strain film 11 to deform, and the deformation amount is proportional to the pressure difference. The distance between the strain film 11 and the fixed electrode 2 is changed to measure the process pressure.

[0053] In one possible implementation, Figure 1 and Figure 2 As shown, the first annular member 12 is provided with a first conductive hole, and the first conductive hole is located in the edge projection area of ​​the strain film 11 .

[0054] Among them, the first annular member 12 is located on the side of the strain film 11 away from the air inlet, that is, the side of the strain film 11 facing the fixed electrode 2, and the first conductive hole is located on the side of the strain film 11 away from the air inlet. A conductive layer is provided in the first conductive hole for leading out the signal of the strain film 11, while improving the sealing of the vacuum pressure detection chamber.

[0055] The two ends of the first conductive hole are open, the first open end of the first conductive hole is connected to the strain film 11 , and the second open end of the first conductive hole faces the fixed electrode 2 .

[0056] In one possible implementation, Figure 3 and Figure 4 As shown, the capacitive film pressure sensor also includes a fixed electrode 2, which includes a ceramic substrate 21. The first surface of the ceramic substrate 21 facing the diaphragm assembly 1 is provided with a conductive coating 22, and the second surface of the ceramic substrate 21 facing away from the diaphragm assembly 1 is provided with a circuit board 23. The ceramic substrate 21 is provided with a second conductive hole 211 connected to the first conductive hole.

[0057] The fixed electrode 2 includes a cylindrical ceramic substrate 21 . A conductive coating 22 of a certain area is electroplated on the first surface of the ceramic substrate 21 facing the strain diaphragm. A second conductive hole 211 is opened in the uncoated area of ​​the ceramic substrate 21 .

[0058] In one possible implementation, Figure 5 As shown, the capacitive film pressure sensor also includes a conductive member 3, which is inserted into the first conductive hole and the second conductive hole 211, a first end of the conductive member 3 is electrically connected to the strain film 11, and a second end of the conductive member 3 is electrically connected to the circuit board 23.

[0059] Among them, a conductive layer is also provided in the second conductive hole 211, the first conductive hole and the second conductive hole 211 are aligned and connected, the first conductive hole and the second conductive hole 211 have basically the same size and are coaxially arranged, so that the conductive member 3 can penetrate the first conductive hole and the second conductive hole 211 to lead the signal of the strain film 11 to the circuit board 23.

[0060] In one possible implementation, Figure 5 As shown, the conductive member 3 is connected to the fixed electrode 2 , and the conductive member 3 is connected to the diaphragm assembly 1 .

[0061] The length of the conductive member 3 is adjustable, and is used to adjust the height difference between the fixed electrode 2 and the strain film 11 .

[0062] The connection position between the conductive member 3 and the fixed electrode 2 and / or the diaphragm assembly 1 is adjustable, so as to adjust the height difference between the fixed electrode 2 and the strain film 11 .

[0063] It can be understood that by changing the length of the conductive part 3, or replacing the conductive part 3 with a different length, or changing the connection position between the fixed electrode 21 and the conductive part 3, or changing the connection position between the diaphragm assembly 1 and the conductive part 3, the distance between the variable electrode and the fixed electrode 2 can be adjusted, and the range of the capacitive film pressure sensor can be flexibly adjusted.

[0064] The conductive member 3 may be a slender conductive metal cylindrical bar with the same diameter as the first conductive hole and the second conductive hole 211 . The first conductive hole and the second conductive hole 211 are connected by the metal bar, so that the signal of the variable electrode can be led out to the circuit board 23 on the fixed electrode 2 .

[0065] In one possible implementation, Figure 3 and Figure 4 As shown, a third conductive hole 221 is opened on the ceramic substrate 21, and the third conductive hole 221 is located in the edge projection area of ​​the conductive coating 22. The third conductive hole 221 is filled with a conductive material, and the first end of the conductive material is electrically connected to the conductive coating 22, and the second end of the conductive material is electrically connected to the circuit board 23.

[0066] The conductive coating 22 area of ​​the ceramic substrate 21 is provided with a third conductive hole 221 , and the third conductive hole 221 is filled with a conductive material, through which the signal of the fixed electrode 2 can be led out to the circuit board 23 on the fixed electrode 2 .

[0067] In traditional semiconductor vacuum equipment and production equipment prepared by special processes, one device usually needs to control multiple capacitive film pressure sensors at the same time. The current common method is to collect signals from each sensor using cables and summarize the collected data on the central processor of the device, which has great limitations.

[0068] In one possible implementation, Figure 3 and Figure 4 As shown, the circuit board 23 includes a capacitance conversion module 232 and a wireless transmission module 231. The capacitance conversion module 232 is used to convert the capacitance signal into a voltage signal. The wireless transmission module 231 is electrically connected to the capacitance conversion module 232. The wireless transmission module 231 is connected to an antenna for receiving the voltage signal and wirelessly transmitting the voltage signal to the terminal.

[0069] The second side of the fixed electrode 2 facing away from the diaphragm assembly 1 can be coated with or electroplated with a conductive coating 22 to construct an antenna and a wire structure required for connecting the second conductive hole 211 and the third conductive hole 221 in a designated area.

[0070] The second surface of the fixed electrode 2 can fix the circuit board 23 by vacuum insulating glue, and the electrical connection between the circuit board 23 and the antenna, the second conductive hole 211 and the third conductive hole 221 can also be achieved by vacuum conductive glue and jumper gold wire.

[0071] The capacitive film pressure sensor may be powered by an external power source or a fixed-capacity power source such as a lithium battery.

[0072] Among them, the circuit board 23 can realize signal conversion through the capacitance conversion module 232. The capacitor film pressure sensor uses the material properties of the strain film 11 to convert pressure into changes in capacitance value. When the pressure changes, the film produces a slight deformation and the capacitance value will change. The capacitance conversion module 232 converts the changed capacitance value into a voltage signal output.

[0073] Among them, the circuit board 23 can realize the wireless transmission function through the wireless transmission module 231. The receiving end of the wireless transmission module 231 is used to receive the voltage signal transmitted by the capacitance conversion module 232, and transmit the voltage signal to the terminal through the antenna through the transmitting end, thereby realizing the wireless measurement of the capacitance film pressure sensor, and can remotely collect data information of multiple sensors at the same time, and can selectively process the signal conversion and reading of multiple capacitance film pressure sensors in a wireless manner.

[0074] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means 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 invention. In this specification, the schematic representation of the above terms does 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.

[0075] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0076] In view of the above detailed description, these and other changes can be made to these embodiments, and this written description includes the best mode embodiments to disclose the present invention. The scope of the patent obtained by the present invention is defined by the claims, which are not limited by the present disclosure, and the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field within the scope disclosed by the present invention, according to the technical solution and its conception of the present invention, is equivalent to or changes, and all are within the protection scope of the present invention.

Claims

1. A capacitive thin film pressure sensor, characterized in that: The invention comprises a diaphragm assembly (1), wherein the diaphragm assembly (1) comprises a strain film (11), a first annular member (12) and a second annular member (13), wherein the strain film (11) is flatly embedded between the first annular member (12) and the second annular member (13), and an outer edge of the strain film (11) is located within a projection area of ​​the first annular member (12) and the second annular member (13).

2. The capacitive thin film pressure sensor according to claim 1, characterized in that: The diaphragm assembly (1) is formed by sintering a strain film (11), a first annular member (12) and a second annular member (13), wherein the first annular member (12) and the second annular member (13) both comprise ceramic material.

3. The capacitive thin film pressure sensor according to claim 1, characterized in that: The outer diameter of the strain film (11) is smaller than the outer diameter of the first annular member (12), and the outer diameter of the strain film (11) is larger than the inner diameter of the first annular member (12); The outer diameter of the strain film (11) is smaller than the outer diameter of the second annular member (13), and the outer diameter of the strain film (11) is larger than the inner diameter of the second annular member (13).

4. The capacitive thin film pressure sensor according to claim 1, characterized in that: The capacitive thin film pressure sensor further comprises a housing (6), and the diaphragm assembly (1) is arranged in the inner cavity of the housing (6).

5. The capacitive thin film pressure sensor according to any one of claims 1 to 4, characterized in that: The first annular member (12) is provided with a first conductive hole (121), and the first conductive hole (121) is located within the edge projection area of ​​the strain film (11).

6. The capacitive thin film pressure sensor according to claim 5, characterized in that: The capacitive thin film pressure sensor also includes a fixed electrode (2), the fixed electrode (2) includes a ceramic substrate (21), a first surface of the ceramic substrate (21) facing the diaphragm assembly (1) is provided with a conductive coating (22), a second surface of the ceramic substrate (21) facing away from the diaphragm assembly (1) is provided with a circuit board (23), and a second conductive hole (211) connected to the first conductive hole (121) is opened on the ceramic substrate (21).

7. The capacitive thin film pressure sensor according to claim 6, characterized in that: The capacitive film pressure sensor further comprises a conductive member (3), wherein the conductive member (3) is inserted through the first conductive hole (121) and the second conductive hole (211), a first end of the conductive member (3) is electrically connected to the strain film (11), and a second end of the conductive member (3) is electrically connected to the circuit board (23).

8. The capacitive thin film pressure sensor according to claim 7, characterized in that: The conductive member (3) is connected to the fixed electrode (2), and the conductive member (3) is connected to the diaphragm assembly (1); The length of the conductive member (3) is adjustable, or the connection position of the conductive member (3) and the fixed electrode (2) and / or the diaphragm assembly (1) is adjustable, so as to adjust the height difference between the fixed electrode (2) and the strain film (11).

9. The capacitive thin film pressure sensor according to any one of claims 6 to 8, characterized in that: A third conductive hole (221) is provided on the ceramic substrate (21), the third conductive hole (221) is located within the edge projection area of ​​the conductive coating (22), the third conductive hole (221) is filled with a conductive material, a first end of the conductive material is electrically connected to the conductive coating (22), and a second end of the conductive material is electrically connected to the circuit board (23).

10. The capacitive thin film pressure sensor according to claim 6, characterized in that: The circuit board (23) comprises: A capacitance conversion module (232), the capacitance conversion module (232) is used to convert the capacitance signal into a voltage signal; A wireless transmission module (231), the wireless transmission module (231) is electrically connected to the capacitance conversion module (232), and the wireless transmission module (231) is connected to an antenna for receiving the voltage signal and wirelessly transmitting the voltage signal to a terminal.

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