Capacitive film vacuum gauge

Abstract

The utility model provides a capacitive film vacuum gauge, which comprises an upper diaphragm capsule, a lower diaphragm capsule and a diaphragm welded between the upper diaphragm capsule and the lower diaphragm capsule, and the lower diaphragm capsule is provided with a pressure inlet joint communicated with the lower diaphragm capsule and used for introducing measured pressure; a sealing opening is formed in the upper diaphragm capsule and is used for vacuumizing; a side pole is arranged on the upper diaphragm capsule, a middle pole is arranged in the middle of the side pole in a penetrating manner, the side pole, the middle pole, the diaphragm, the upper diaphragm capsule and the lower diaphragm capsule jointly form a measuring diaphragm capsule capable of generating capacitance change through bending of the diaphragm, and a circuit board and a reference capacitor are introduced into the measuring diaphragm capsule; according to the vacuum gauge, a side pole and a middle pole form a single capacitor, a diaphragm, an upper diaphragm capsule and a lower diaphragm capsule are matched to measure a vacuum cavity to be measured, a reference capacitor serves as a reference, the reference capacitor serves as a fixed capacitor, does not change along with pressure change and only changes along with the environment, two capacitance values are compared and then adjusted through a circuit board, and a linear voltage value is output. The vacuum gauge eliminates environmental influence and has good stability and continuity.

Description

Technical Field

[0001] The utility model relates to a thin-film vacuum gauge, in particular to a capacitive thin-film vacuum gauge. Background Art

[0002] With the development of new technologies such as photovoltaic, semiconductor, and nuclear energy, many technological processes need to operate in a certain vacuum environment. Therefore, the measurement and control of the vacuum environment are particularly important.

[0003] Current vacuum gauge products are divided into two categories. One category uses imported ceramic capacitive sensors as the core components, and the other category uses self-produced metal double capacitors as the core components. There are some measurement problems with both current types of products: the ceramic diaphragm of the imported ceramic capacitive sensor product will stick to various powders during the measurement process, and the zero drift is relatively large after long-term use, requiring frequent calibration, which is not conducive to long-term measurement; for the other category of products with metal double capacitors as the core components, although they do not stick to powders, due to the large area required for the two electrodes, the influence of environmental changes increases, resulting in zero and full-scale drift. The current solution is to heat the sensor itself, but it cannot completely avoid the drift of the sensor. Therefore, it is necessary to design a vacuum gauge that can overcome environmental influences and measure stably. Summary of the Utility Model

[0004] In order to overcome the shortcomings in the above background art, the utility model provides a capacitive thin-film vacuum gauge with little influence from the environment and stable measurement.

[0005] The technical solution of the utility model is: a capacitive thin-film vacuum gauge, including an upper diaphragm box, a lower diaphragm box, and a diaphragm welded between the upper and lower diaphragm boxes. The lower diaphragm box is provided with a pressure inlet joint communicated therewith for introducing the measured pressure; the upper diaphragm box is provided with a sealing port for vacuum pumping; the upper diaphragm box is provided with an edge electrode, and a middle electrode penetrates through the middle of the edge electrode. The edge electrode, the middle electrode, the diaphragm, and the upper and lower diaphragm boxes together form a measurement diaphragm box that can generate capacitance changes through the bending of the diaphragm. The measurement diaphragm box is introduced into a circuit board and a reference capacitor. Among them, the reference capacitor is used as a fixed capacitor and only changes with the environment. After the capacitance value generated by the measurement diaphragm box is compared with the capacitance value of the reference capacitor, it is adjusted into a voltage signal output through the circuit board.

[0006] In addition, particularly preferably, the middle electrode is fixed in the middle of the edge electrode by sintering, and an insulating material is provided between the middle electrode and the edge electrode.

[0007] In addition, particularly preferably, the insulating material is vitreous enamel.

[0008] In addition, particularly preferably, the upper and lower diaphragm boxes and the diaphragm are welded by micro-plasma welding.

[0009] In addition, it is particularly preferred that a housing protective cover and a housing base are further included. The housing base is arranged on the inlet crimping joint, and the housing protective cover is arranged on the housing base to protect the entire measuring diaphragm box and the circuit board.

[0010] The beneficial effects are as follows: The vacuum gauge forms a single capacitor with the edge electrode and the middle electrode, cooperates with the diaphragm and the upper and lower diaphragm boxes to measure the vacuum cavity to be measured, and uses the reference capacitor as a reference. The reference capacitor is a fixed capacitor, which does not change with pressure but only changes with the environment. After the two capacitance values are compared, they are adjusted by the circuit board and a linear voltage value is output. The vacuum gauge eliminates the environmental influence and has good stability and continuity. Description of the Drawings

[0011] Figure 1 It is a schematic structural diagram of the capacitive thin-film vacuum gauge of the present utility model.

[0012] Figure 2 It is a circuit diagram of the present utility model.

[0013] In the reference numerals of the drawings: 1 - lower diaphragm box, 2 - diaphragm, 3 - upper diaphragm box, 4 - seal port, 5 - circuit board, 6 - middle electrode, 7 - glass glaze, 8 - edge electrode, 9 - housing protective cover, 10 - housing base, 11 - inlet crimping joint, 12 - reference capacitor. Detailed Embodiments

[0014] The following further describes the present utility model in detail in conjunction with the drawings and specific embodiments, but does not limit the protection scope and application scope of the present utility model.

[0015] Although relative terms such as "upper" and "lower" are used in this specification to describe the relative relationship of one component of the icon to another component, these terms are used in this specification only for convenience, for example, according to the direction of the example described in the drawings. It can be understood that if the device of the icon is turned upside down, the component described as "upper" will become the component described as "lower". Other relative terms such as "high", "low", "top", "bottom", "left", "right", etc. also have similar meanings. When a structure is "on" another structure, it may mean that a structure is integrally formed on another structure, or that a structure is "directly" arranged on another structure, or that a structure is "indirectly" arranged on another structure through another structure. The following further describes the present utility model in detail in conjunction with the drawings and specific embodiments, but does not limit the present utility model.

[0016] As Figure 1The capacitive thin-film vacuum gauge shown includes an upper diaphragm box 3, a lower diaphragm box 1, and a diaphragm 2. Among them, the diaphragm 2 is welded between the upper diaphragm box 3 and the lower diaphragm box 1. The diaphragm 2 divides the cavity formed by the upper diaphragm box 3 and the lower diaphragm box 1 into two parts. The space formed by the diaphragm 2 and the upper diaphragm box 3 is the upper cavity, and the space formed by the diaphragm 2 and the lower diaphragm box 1 is the lower cavity; a pressure inlet joint 11 is provided on the lower diaphragm box 1, and the pressure inlet joint 11 communicates the outside with the lower cavity for introducing the measured pressure; an edge electrode 8 and a middle electrode 6 are provided on the upper diaphragm box 3. Among them, the middle electrode 6 is disposed through the middle of the edge electrode 8. Specifically, in this embodiment, the middle electrode 6 is fixed in the middle of the edge electrode 8 by sintering. An insulating material is provided between the middle electrode 6 and the edge electrode 8. This insulating material can be ceramics, glass, resin, etc., preferably glass glaze 7. In addition, a sealing port 4 is further provided on the upper diaphragm box 3. This sealing port 4 is used as an atmospheric reference. After the measurement diaphragm box is manufactured, it is necessary to evacuate the upper cavity through the sealing port 4, and finally seal the sealing port 4.

[0017] The edge electrode 8, the middle electrode 6, the diaphragm 2, and the upper diaphragm box 3 and the lower diaphragm box 1 together form a measurement diaphragm box that can generate a capacitance change through the bending of the diaphragm 2. When measuring the vacuum degree of the cavity, the front end of the pressure inlet joint 11 is connected to the cavity to be measured. After the diaphragm 2 is pressed, it will bend towards the upper diaphragm box 3 and approach the single capacitor formed by the edge electrode 8 and the middle electrode 6, and change the capacitance of the single capacitor. This capacitance changes linearly with the pressure. In addition, a circuit board 5 and a reference capacitor 12 are introduced into this measurement diaphragm box. Among them, the reference capacitor 12 is a fixed capacitor that does not change with pressure but only changes with the environment. Therefore, the reference capacitance value can eliminate the influence of environmental changes on the single capacitor. After comparing the two capacitance values, the measured capacitance value is adjusted into a voltage signal through the circuit board 5 and a linear voltage value is output.

[0018] In addition, it should be noted that the edge electrode 8 is fixed on the upper diaphragm box 3 by welding.

[0019] As Figure 2 shown in the circuit conversion diagram, where the capacitance is converted into a voltage signal through an oscillation circuit. In the figure, CY is the reference capacitor and C is the measured capacitor. The working principle is as follows: In the positive half cycle of the square wave signal, D2 and D3 are turned on, and Vref charges Cx through resistors R3, R1, D2 and charges Cy through resistors R4, R2, D4. In the negative half cycle of the square wave signal, D2 and D3 are turned on, Cy discharges through D1, R1, C3, and Cx discharges through resistors D3, R2, C4. Since the charging terminal voltage across the capacitor is inversely proportional to the capacitance, a voltage difference is formed across C3 and C4. This voltage difference signal is amplified by the operational amplifier U1B, and a voltage signal corresponding to the capacitance value of Cx is output. Then, through linear calibration, temperature compensation, and signal amplification, a vacuum gauge measurement product with a standard signal output is manufactured.

[0020] It should also be noted that the diaphragm 2 is welded to the upper diaphragm box 3 and the lower diaphragm box 1 by micro-plasma welding. During the welding process, the flatness of the diaphragm 2 is ensured. After welding, leak detection is carried out under a helium mass spectrometer leak detector, and there should be no phenomena such as air leakage and sand holes. After the welding inspection is qualified, the upper cavity needs to be evacuated to a vacuum state through the sealing port 4 and then the sealing port 4 is sealed. Thus, the production of the measuring diaphragm box is completed. After the production of the diaphragm box is completed, the capacitance signal needs to be conditioned into the signals required by the system: 4-20 mA, 0-10 V or RS485 signal. After the signal conditioning is completed, the vacuum gauge circuit board 5 is fixed to the measuring diaphragm box, and then the pressure inlet joint 11 is welded in.

[0021] In addition, the vacuum gauge further includes a housing protective cover 9 and a housing base 10. The housing base 10 is arranged on the pressure inlet joint 11, and the housing protective cover 9 is arranged on the housing base 10 to protect the entire measuring diaphragm box and the circuit board 5.

[0022] The above-described embodiments only represent the preferred embodiments of the present invention, and the description is relatively specific and detailed. However, it should not be construed as a limitation of the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations, improvements and substitutions can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. A capacitive thin-film vacuum gauge, comprising an upper diaphragm chamber (3), a lower diaphragm chamber (1), and a diaphragm (2) welded between the upper and lower diaphragm chambers (3, 1). The lower diaphragm chamber (1) is provided with an inlet pressure joint (11) communicated therewith for introducing the measured pressure. The upper diaphragm chamber (3) is provided with a sealing port (4) for evacuating the air. It is characterized in that: An edge electrode (8) is provided on the upper diaphragm box (3). A middle electrode (6) penetrates through the middle of the edge electrode (8). The edge electrode (8), the middle electrode (6), the diaphragm (2), and the upper and lower diaphragm boxes (3, 1) together form a measuring diaphragm box that can generate capacitance changes through the bending of the diaphragm (2). The measuring diaphragm box is introduced into a circuit board (5) and a reference capacitor (12). Among them, the reference capacitor (12) is used as a fixed capacitor and only changes with the environment. After the capacitance value generated by the measuring diaphragm box is compared with the capacitance value of the reference capacitor (12), it is adjusted into a voltage signal output through the circuit board (5).

2. The capacitive thin-film vacuum gauge according to claim 1, characterized in that: The middle electrode (6) is fixed in the middle of the edge electrode (8) in a sintering manner, and an insulating material is provided between the middle electrode (6) and the edge electrode (8).

3. The capacitance thin-film vacuum gauge according to claim 2, wherein: The insulating material is glass glaze (7).

4. The capacitance thin-film vacuum gauge according to claim 1, characterized in that: The upper and lower diaphragm boxes (3, 1) and the diaphragm (2) are welded by microbeam plasma welding.

5. The capacitive thin-film vacuum gauge according to any one of claims 1-4, characterized in that: It further includes a housing protective cover (9) and a housing base (10). The housing base (10) is provided on the inlet pressure joint (11), and the housing protective cover (9) is provided on the housing base (10) to protect the entire measuring diaphragm box and the circuit board (5).

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