CN115597767A - Vacuum degree detection circuit, vacuum gauge and vacuum degree detection method - Google Patents
Vacuum degree detection circuit, vacuum gauge and vacuum degree detection method Download PDFInfo
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- CN115597767A CN115597767A CN202211275215.5A CN202211275215A CN115597767A CN 115597767 A CN115597767 A CN 115597767A CN 202211275215 A CN202211275215 A CN 202211275215A CN 115597767 A CN115597767 A CN 115597767A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L21/00—Vacuum gauges
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
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- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
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- G—PHYSICS
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Abstract
The embodiment of the invention provides a vacuum degree detection circuit, a vacuum gauge and a vacuum degree detection method, belonging to the technical field of vacuum measurement, wherein the vacuum degree detection circuit comprises: the device comprises a carrier generation module, a capacitance detection module and an output processing module which are connected in sequence. The vacuum degree detection circuit provided by the embodiment of the invention is provided with the carrier generation module, the capacitance detection module and the output processing module which are sequentially connected, the capacitance detection module is provided with the capacitance bridge comprising the inner ring capacitance of the film capacitor, the carrier is used as the voltage input end of the capacitance bridge, the square wave with the same frequency as the carrier is used for controlling the switch circuit, the switch circuit is respectively communicated with two midpoint voltage signals of the capacitance bridge in the square wave change direction, and the output processing module is used for processing the signal output by the switch circuit to obtain the direct current voltage signal reflecting the vacuum degree.
Description
Technical Field
The embodiment of the invention relates to the technical field of vacuum measurement, in particular to a vacuum degree detection circuit, a vacuum gauge and a vacuum degree detection method.
Background
Vacuum measurement technology is widely applied to the fields of semiconductor manufacturing, chemical metallurgy, aerospace and the like, along with the continuous progress of science and technology, the requirements of the fields on vacuum instruments are increasing day by day, and vacuum degree detection technical schemes based on different principles are also endless, such as: compression type vacuum detection, hot cathode ionization vacuum detection, pirani thermal resistance vacuum detection and the like. Different detection schemes are suitable for different vacuum measurement ranges, convection vacuum detection, mercury column vacuum detection, resistance vacuum detection, thermocouple vacuum detection and the like are suitable for medium and low vacuum ranges, and ionization vacuum detection, hot cathode magnetic control vacuum detection and thin film capacitance vacuum detection schemes are suitable for medium and high vacuum ranges.
Fig. 1 is a schematic structural diagram of a detection circuit of a prior art capacitance type thin film vacuum gauge based on a digital scheme. The scheme adopts a digital control scheme, an ARM controller needs to generate a carrier wave through a digital-to-analog conversion module, an analog signal output by an operational amplifier of a capacitance detection part needs to be acquired through the digital-to-analog conversion module, and the defect of the scheme mainly has two aspects: 1) The ARM controller generates a step-shaped carrier wave through the digital-to-analog conversion module, which causes high noise of a test result, and high-frequency noise of a digital device causes interference to cause high noise of the test result; 2) The cost of the scheme is high because a digital-to-analog conversion module and an analog-to-digital conversion module need to be additionally added.
Disclosure of Invention
Aiming at the defects in the prior art, the embodiment of the invention provides a vacuum degree detection circuit, a vacuum gauge and a vacuum degree detection method.
The embodiment of the invention provides a vacuum degree detection circuit, which comprises a carrier generation module, a capacitance detection module and an output processing module which are connected in sequence; wherein: the capacitance detection module comprises a switch circuit, a square wave signal generation circuit and a capacitance bridge formed by a first capacitor, a second capacitor, a reference capacitor and an inner ring capacitor of a film capacitor, wherein the capacitance values of the first capacitor and the second capacitor are the same, and the capacitance values of the reference capacitor and the inner ring capacitor in a vacuum state are the same; the common point of the first capacitor and the inner ring capacitor is connected with a first signal input end of the switch circuit, and the common point of the second capacitor and the reference capacitor is connected with a second signal input end of the switch circuit; the common point of the first capacitor and the second capacitor is connected with the carrier output end of the carrier generation module, and the common point of the reference capacitor and the inner ring capacitor is grounded; or, a common point of the first capacitor and the second capacitor is grounded, and a common point of the reference capacitor and the inner loop capacitor is connected to a carrier output end of the carrier generation module; the signal output end of the square wave signal generating circuit is connected with a switch enabling port of the switch circuit, the square wave signal generating circuit outputs a square wave signal with the same frequency as the carrier wave output by the carrier wave generating module, and when the square wave signal changes direction, the signal output end of the switch circuit is switched between being communicated with the first signal input end and being communicated with the second signal input end; the signal output end of the switch circuit is connected with the input end of the output processing module, and the output processing module processes the received signal to obtain a direct current voltage signal reflecting the vacuum degree.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the capacitance values of the first capacitor, the second capacitor, the reference capacitor and the inner ring capacitor of the film capacitor in a vacuum state are the same.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the square wave signal generation circuit comprises a comparator; the carrier output end of the carrier generation module is connected with the positive input end of the comparator, and the negative input end of the comparator is grounded; or the carrier output end of the carrier generation module is connected with the negative input end of the comparator, and the positive input end of the comparator is grounded.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the reference capacitance is the outer ring capacitance of the film capacitor.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the vacuum degree detection circuit further comprises a first negative feedback module; the input end of the first negative feedback module is connected with the carrier output end of the carrier generation module, and the output end of the first negative feedback module is connected with the signal input end of the carrier generation module.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the first negative feedback module comprises a first low-pass filter, a first proportional operation circuit and a PI (proportional integral) regulation module which are sequentially connected; the input end of the first low-pass filter is connected with the carrier output end of the carrier generation module, and the output end of the PI regulation module is connected with the signal input end of the carrier generation module.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the vacuum degree detection circuit further comprises a second negative feedback module; the input end of the second negative feedback module is connected with the signal output end of the switch circuit, and the output end of the second negative feedback module is connected with the signal input end of the carrier generation module.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the second negative feedback module comprises a second low-pass filter, a second proportional operation circuit and the PI regulation module which are sequentially connected; wherein an input terminal of the second low-pass filter is connected to the signal output terminal of the switching circuit.
The embodiment of the invention also provides a vacuum gauge which comprises any one of the vacuum degree detection circuits.
The embodiment of the invention also provides a vacuum degree detection method based on any vacuum degree detection circuit, which comprises the following steps: based on different test air pressures, acquiring output voltage of the output processing module and calibration data of the test air pressure; and acquiring a current measured air pressure value according to the calibration data and the voltage signal output by the output processing module during actual measurement.
The embodiment of the present invention further provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor implements any of the above steps of the vacuum degree detection method when executing the program.
Embodiments of the present invention further provide a non-transitory computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of any of the vacuum degree detection methods described above.
Embodiments of the present invention further provide a computer program product, which includes a computer program, and when the computer program is executed by a processor, the steps of the vacuum degree detection method described in any of the above are implemented.
The vacuum degree detection circuit, the vacuum gauge and the vacuum degree detection method provided by the embodiment of the invention have the advantages that through the arrangement of the carrier generation module, the capacitance detection module and the output processing module which are sequentially connected, the capacitance detection module is provided with the capacitance bridge comprising the inner ring capacitance of the film capacitor, the inner ring capacitance generates the capacitance change under the action of the gas pressure, the carrier is used as the voltage input end of the capacitance bridge, the switching circuit is controlled by utilizing the square wave with the same frequency as the carrier, the switching circuit is respectively communicated with two midpoint voltage signals of the capacitance bridge in the square wave change direction, and the output processing module is used for processing the signals output by the switching circuit to obtain the direct current voltage signals reflecting the vacuum degree.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings required for the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic diagram of a prior art digital scheme-based detection circuit of a capacitive film gauge;
FIG. 2 is a schematic diagram of a vacuum detection circuit according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a capacitance detection module of the vacuum detection circuit according to an embodiment of the present invention;
FIG. 4 is a second schematic diagram of a capacitance detection module of the vacuum detection circuit according to the second embodiment of the present invention;
FIG. 5 is a diagram illustrating test results of a vacuum detection circuit according to an embodiment of the present invention;
FIG. 6 is a diagram showing the test results of a vacuum detection circuit of the prior art digital scheme;
FIG. 7 is a third schematic structural diagram of a capacitance detection module of the vacuum detection circuit according to the embodiment of the present invention;
FIG. 8 is a fourth schematic diagram of the capacitance detection module of the vacuum detection circuit according to the embodiment of the present invention;
FIG. 9 is a fifth schematic view of a capacitance detection module of the vacuum detection circuit according to the embodiment of the present invention;
FIG. 10 is a sixth schematic diagram of a capacitance detection module of the vacuum detection circuit according to the embodiment of the present invention;
FIG. 11 is a second schematic diagram of a vacuum detection circuit according to an embodiment of the present invention;
FIG. 12 is a schematic flow chart illustrating a method for detecting vacuum level according to an embodiment of the present invention;
fig. 13 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The vacuum degree detection circuit provided by the embodiment of the invention is a vacuum degree detection circuit based on a thin film capacitor, which is realized by an analog circuit.
Fig. 2 is a schematic structural diagram of a vacuum level detection circuit according to an embodiment of the present invention. As shown in fig. 2, the vacuum degree detection circuit includes: a carrier generation module 10, a capacitance detection module 20 and an output processing module 30 connected in sequence.
Fig. 3 is a schematic structural diagram of a capacitance detection module of the vacuum detection circuit according to an embodiment of the present invention. Fig. 4 is a second schematic structural diagram of a capacitance detection module of the vacuum detection circuit according to the embodiment of the present invention. As shown in fig. 2, 3, and 4:
the capacitance detection module 20 includes a switch circuit 201, a square wave signal generation circuit 202, and a capacitance bridge formed by a first capacitance C1, a second capacitance C2, a reference capacitance Cref, and an inner-ring capacitance Cx of a film capacitor, where the capacitance values of the first capacitance C1 and the second capacitance C2 are the same, and the capacitance values of the reference capacitance Cref and the inner-ring capacitance Cx in a vacuum state are the same; the common point of the first capacitor C1 and the inner loop capacitor Cx is connected to the first signal input terminal of the switch circuit 201, and the common point of the second capacitor C2 and the reference capacitor Cref is connected to the second signal input terminal of the switch circuit 201;
the common point of the first capacitor C1 and the second capacitor C2 is connected to the carrier output terminal of the carrier generation module 10, and the common point of the reference capacitor Cref and the inner-loop capacitor Cx is grounded (as shown in fig. 3);
alternatively, the common point of the first capacitor C1 and the second capacitor C2 is grounded, and the common point of the reference capacitor Cref and the inner-loop capacitor Cx is connected to the carrier output terminal of the carrier generation module 10 (as shown in fig. 4);
the signal output end of the square wave signal generating circuit 202 is connected to the switch enable port of the switch circuit 201, the square wave signal generating circuit 202 outputs a square wave signal having the same frequency as the carrier wave output by the carrier wave generating module 10, and when the square wave signal changes direction, the signal output end of the switch circuit 201 is switched between being communicated with the first signal input end and being communicated with the second signal input end;
the signal output end of the switch circuit 201 is connected to the input end of the output processing module 30, and the output processing module 30 processes the received signal to obtain a direct current voltage signal reflecting the vacuum degree.
In order to test the vacuum degree of the gas, the inner ring capacitance Cx of the film capacitor is connected into a capacitance bridge by utilizing the characteristic that the film capacitance can change the distance between capacitance plates along with the increase of the gas pressure so as to influence the capacitance value of the film capacitor. The carrier generation module 10 generates a carrier signal and loads the carrier signal to the capacitor bridge, and the midpoint voltage amplitude of the capacitor bridge arm can reflect the variation of the inner-ring capacitance of the thin-film capacitor, so that the variation of the gas vacuum degree is obtained.
The vacuum degree detection circuit provided by the embodiment of the invention comprises a carrier generation module 10, a capacitance detection module 20 and an output processing module 30 which are sequentially connected, wherein the carrier generation module 10 generates a sine carrier with adjustable amplitude, and the sine carrier can be realized by an oscillating circuit, such as a Venturi bridge circuit, an LC sine wave oscillating circuit and the like; the capacitance detection module 20 includes a switch circuit 201, a square wave signal generation circuit 202, and a capacitance bridge formed by a first capacitance C1, a second capacitance C2, a reference capacitance Cref, and an inner ring capacitance Cx of the film capacitor, where the capacitance values of the first capacitance C1 and the second capacitance C2 are the same, and the capacitance values of the reference capacitance Cref and the inner ring capacitance Cx in a vacuum state are the same, and are represented as:
C 1 ＝C 2 ,C ref ＝C x (1)
wherein: c 1 Representing the electricity of the first capacitor C1Volume value, C 2 Represents the capacitance value of the second capacitor C2, C ref Representing the capacitance value, C, of the reference capacitance Cref x The capacitance value of the inner ring capacitance Cx of the thin film capacitor in a vacuum state is referred to as an initial capacitance value of the inner ring capacitance Cx of the thin film capacitor, and the capacitance value of the inner ring capacitance Cx changes under the action of the measured air pressure.
The common point of the first capacitor C1 and the inner loop capacitor Cx is connected to the first signal input terminal of the switch circuit 201, and the common point of the second capacitor C2 and the reference capacitor Cref is connected to the second signal input terminal of the switch circuit 201. I.e. the two midpoint voltages of the capacitive bridge are connected to the first signal input and the second signal input of the switching circuit 201.
The switching circuit 201 switches between the signal output terminal and the first and second signal input terminals under the action of the input square wave signal. When the square wave signal is at high level, the first signal input end is communicated, and when the square wave signal is at low level, the second signal input end is communicated. The switch circuit 201 may select an existing device, such as an analog switch of model MAX4693 ETE.
The signal output end of the square wave signal generating circuit 202 is connected to the switch enabling port of the switch circuit 201, and the square wave signal generating circuit 202 outputs a square wave signal having the same frequency as the carrier wave output by the carrier wave generating module 10, that is, the carrier wave and the square wave signal change directions at the same time. Because the carrier output by the carrier output end of the carrier generation module 10 is used as the input voltage of the capacitor bridge, under the condition that the square wave signal and the carrier have the same frequency, the parameters of the capacitor bridge in the initial state (in the vacuum state) are as shown in formula (1), the voltage amplitudes of the first signal input end and the second signal input end of the switch circuit 201 are equal, and the switch circuit 201 outputs a sine wave with the positive half period and the negative half period having the same amplitude; when the capacitance Cx of the capacitor to be measured, i.e., the inner-loop capacitor of the thin-film capacitor, changes, the voltage amplitude of the first signal input terminal also changes, the voltage amplitude of the first signal input terminal is no longer equal to the voltage amplitude of the second signal input terminal, and the switching circuit 201 outputs a sine wave with unequal amplitudes of the positive half cycle and the negative half cycle.
The signal output end of the switch circuit 201 is connected to the input end of the output processing module 30, and the output processing module 30 processes the received signal to obtain a voltage signal reflecting the vacuum degree. The output processing module 30 performs low-pass filtering on the signal output by the signal output end of the switch circuit 201 to obtain a direct current component, and the magnitude of the direct current component represents the magnitude of the variation of the capacitance Cx to be measured and can reflect the variation of the pressure of the gas to be measured. The processing operations of the output processing module 30 may include filtering and amplification, and active filtering and signal amplification circuits may be built using operational amplifiers. The filtering function is to filter the sine wave with unequal amplitudes of the positive half cycle and the negative half cycle output by the switching circuit 201 and obtain a direct current component, and the purpose of the amplification is to regulate the signal to a voltage range (such as 0-10V) convenient for measurement and cascade connection of other instruments, namely, the function of adjusting the scale, wherein the voltage can represent the measured gas pressure. After the filtering process, if the obtained dc component is a negative value, the dc component may be subjected to an inversion process before or after the amplification process.
The output voltage of the output processing module and the calibration data of the test air pressure can be obtained in advance based on different test air pressures, and after calibration, the output voltage value of the output processing module 30 can represent the measured air pressure value, so that the vacuum degree can be obtained according to the finally obtained direct-current voltage signal.
If the output voltage is adjusted to be in the range of 0-10V, the voltage of 0-10V can linearly correspond to the air pressure value from the vacuum state to the full range. For example, in the case of a full scale of 0.1torr (pressure unit), the output voltage is close to 0V when the pressure to be measured is in a state close to vacuum, and the output voltage is 10V when the pressure to be measured is 0.1 torr.
If the carrier signal and the square wave signal are in the same frequency and phase, when the carrier signal is in a positive half period, the signal of the first signal input end is in the positive half period, the switch circuit 201 is communicated with the first signal input end, the waveform output by the switch circuit 201 is also in the positive half period, when the carrier signal is in a negative half period, the signal of the second signal input end is in the negative half period, the switch circuit 201 is communicated with the second signal input end, and the waveform output by the switch circuit 201 is also in the negative half period. If the carrier signal and the square wave signal are in the same frequency and different phases, the waveform output by the switch circuit 201 will be in the opposite phase.
In the vacuum degree detection circuit shown in fig. 2 and 3, the common point of the first capacitor C1 and the second capacitor C2 is connected to the carrier output terminal of the carrier generation module 10, and the common point of the reference capacitor Cref and the inner loop capacitor Cx is grounded. The voltage amplitude at the first signal input terminal is then:
wherein, V ZB Representing the amplitude of the carrier wave.
The voltage amplitude of the second signal input terminal is:
taking the same frequency and phase of the carrier signal and the square wave signal as an example, when the inner ring capacitance Cx of the film capacitor increases due to the gas pressure, the film distance decreases, so that the capacitance C x When increasing, the voltage amplitude V of the first signal input terminal 1 Reducing the voltage amplitude V of the second signal input 2 The output waveform of the switching circuit 201 is filtered to obtain a negative dc component, and the dc component is inverted and amplified to obtain a dc voltage signal reflecting the pressure.
In the vacuum degree detection circuit shown in fig. 2 and 4, the common point of the first capacitor C1 and the second capacitor C2 is grounded, and the common point of the reference capacitor Cref and the inner ring capacitor Cx is connected to the carrier output terminal of the carrier generation module 10. The voltage amplitude at the first signal input terminal is then:
the voltage amplitude of the second signal input terminal is:
taking the same frequency and phase of the carrier signal and the square wave signal as an example, when the inner ring capacitance Cx of the film capacitor increases due to the gas pressure, the film distance decreases, so that the capacitance C x When increasing, the voltage amplitude V of the first signal input terminal 1 Increasing the voltage amplitude V of the second signal input terminal 2 The output waveform of the switching circuit 201 is filtered to obtain a positive dc component, and the dc component is amplified to obtain a dc voltage signal reflecting the pressure.
In the prior art, the sinusoidal carrier generated in a digital mode is in a step shape, which causes large noise of a test result, and high-frequency noise of a digital signal also causes interference, which causes large noise of the test result and high cost. The vacuum degree detection circuit provided by the embodiment of the invention adopts an analog design scheme, namely the vacuum degree detection circuit is designed by completely adopting an analog circuit. In the analog design scheme, except that the carrier signal frequency is in the kHz magnitude, other signals are low-frequency signals, so that extra high-frequency interference cannot be caused, and in the digital design scheme, the digital signal frequency can even reach the MHz magnitude, so that the hidden danger of high-frequency noise interference can be caused. In addition, the cost of the digital scheme is high, and the cost of the analog scheme can be reduced by about 3/4 compared with the digital scheme.
Fig. 5 is a schematic diagram of a test result of the vacuum degree detection circuit provided in the embodiment of the present invention. FIG. 6 is a diagram showing the test results of a vacuum detection circuit of the prior art digital scheme. As shown in FIG. 5, the 12 hour stability test results using a vacuum gauge with a 0.1Torr range for example, have a noise of 0.00359mTorr, which is less noisy than the digital scheme shown in FIG. 6.
The vacuum degree detection circuit provided by the embodiment of the invention is characterized in that a carrier generation module, a capacitance detection module and an output processing module which are connected in sequence are arranged, a capacitance bridge comprising an inner ring capacitance of a film capacitor is arranged on the capacitance detection module, the inner ring capacitance generates capacitance change under the action of gas pressure, the carrier is used as a voltage input end of the capacitance bridge, a switching circuit is controlled by utilizing square waves with the same frequency as the carrier, the switching circuit is respectively communicated with two midpoint voltage signals of the capacitance bridge in the square wave change direction, and a direct current voltage signal reflecting the vacuum degree can be obtained after the output processing module processes the signal output by the switching circuit.
According to the vacuum degree detection circuit provided by the embodiment of the present invention, the capacitance values of the first capacitor C1, the second capacitor C2, the reference capacitor Cref and the inner ring capacitance Cx of the film capacitor in the vacuum state are the same.
In the embodiment of the invention, the capacitance values of the first capacitor C1, the second capacitor C2, the reference capacitor Cref and the inner ring capacitor Cx of the film capacitor are the same in the vacuum state. The first capacitor C1, the second capacitor C2 and the reference capacitor Cref are not affected by the air pressure, and the inner ring capacitor Cx of the film capacitor is subjected to capacitance change under the action of the air pressure.
The vacuum degree detection circuit provided by the embodiment of the invention is beneficial to simplifying the subsequent processing process by setting the first capacitor C1, the second capacitor C2, the reference capacitor Cref and the inner ring capacitor Cx of the film capacitor to have the same capacitance value in the vacuum state.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the square wave signal generation circuit 202 comprises a comparator; a carrier output end of the carrier generation module 10 is connected to a positive input end of the comparator, and a negative input end of the comparator is grounded; or the carrier output end of the carrier generation module is connected with the negative input end of the comparator, and the positive input end of the comparator is grounded.
Fig. 7 is a third schematic structural diagram of a capacitance detection module of the vacuum detection circuit according to the embodiment of the present invention. As shown in fig. 7, the switching signal (square wave signal) of the analog switch is generated by the carrier and GND through the comparator, the carrier is connected to the positive input terminal of the comparator, the GND is connected to the negative input terminal of the comparator, and the carrier and the square wave have the same frequency and the same phase. The analog switch is connected to signal 1 when the carrier is in the positive half cycle and to signal 2 when the carrier is in the negative half cycle. The capacitance values of the first capacitor C1 and the second capacitor C2 are the same, the initial capacitance values of the reference capacitor Cref and the inner-ring capacitor Cx of the film capacitor are the same, a voltage waveform with equal positive and negative half-cycle amplitude can be measured at the output port of the analog switch, and the direct-current component after low-pass filtering in the output link is 0; when the capacitance value of the film capacitor is increased due to the fact that the film distance of the film capacitor is reduced due to the fact that the pressure of the measured gas is increased, the voltage amplitude of the position of a signal 1 is reduced, the analog switch outputs a waveform with a small positive half period amplitude and a large negative half period amplitude, a negative direct current component is obtained after low-pass filtering is carried out in an output link, the negative direct current component is subjected to phase inversion and amplification, and the signal can be adjusted to be within a voltage range which is convenient to measure and cascade other instruments.
Fig. 8 is a fourth schematic structural diagram of a capacitance detection module of the vacuum degree detection circuit according to the embodiment of the present invention. As shown in fig. 8, the switching signal (square wave signal) of the analog switch is generated by the carrier and GND through the comparator, the carrier is connected to the negative input terminal of the comparator, the GND is connected to the positive input terminal of the comparator, and the carrier and the square wave have the same frequency and are out of phase. The analog switch is connected to signal 2 when the carrier is in the positive half cycle and to signal 1 when the carrier is in the negative half cycle. The capacitance values of the first capacitor C1 and the second capacitor C2 are the same, the initial capacitance values of the reference capacitor Cref and the inner-ring capacitor Cx of the film capacitor are the same, a voltage waveform with equal positive and negative half-cycle amplitude can be measured at the output port of the analog switch, and the direct-current component after low-pass filtering in the output link is 0; when the capacitance value of the film capacitor is increased due to the fact that the film distance of the film capacitor is reduced due to the fact that the pressure of the measured gas is increased, the voltage amplitude of the position of a signal 1 is reduced, the analog switch outputs a waveform with a large positive half period amplitude and a small negative half period amplitude, a positive direct current component is obtained after low-pass filtering is carried out in an output link, the positive direct current component is amplified, and the signal can be adjusted to be within a voltage range which is convenient to measure and cascade other instruments.
Fig. 9 is a fifth structural schematic diagram of the capacitance detection module of the vacuum degree detection circuit according to the embodiment of the present invention. As shown in fig. 9, a switching signal (square wave signal) of the analog switch is generated by a carrier and GND through a comparator, the carrier is connected to a positive input terminal of the comparator, the GND is connected to a negative input terminal of the comparator, and the carrier and the square wave have the same frequency and the same phase. The analog switch is connected to signal 1 when the carrier is in the positive half cycle and to signal 2 when the carrier is in the negative half cycle. The capacitance values of the first capacitor C1 and the second capacitor C2 are the same, the initial capacitance values of the reference capacitor Cref and the inner-ring capacitor Cx of the film capacitor are the same, a voltage waveform with equal positive and negative half-cycle amplitudes can be measured at the output port of the analog switch, and the direct-current component after low-pass filtering in the output link is 0; when the capacitance value of the film capacitor is increased due to the fact that the film distance of the film capacitor is reduced due to the fact that the pressure of the measured gas is increased, the voltage amplitude of the position of a signal 1 is increased, the analog switch outputs a waveform with a large positive half period amplitude and a small negative half period amplitude, a positive direct current component is obtained after low-pass filtering is carried out in an output link, the positive direct current component is amplified, and the signal can be adjusted to be within a voltage range which is convenient to measure and cascade other instruments.
Fig. 10 is a sixth schematic structural diagram of a capacitance detection module of the vacuum detection circuit according to the embodiment of the present invention. As shown in fig. 10, the switching signal (square wave signal) of the analog switch is generated by the carrier and GND through the comparator, the carrier is connected to the negative input terminal of the comparator, the GND is connected to the positive input terminal of the comparator, and the carrier and the square wave are in the same frequency and are out of phase. The analog switch is connected to signal 2 when the carrier is in the positive half cycle and to signal 1 when the carrier is in the negative half cycle. The capacitance values of the first capacitor C1 and the second capacitor C2 are the same, the initial capacitance values of the reference capacitor Cref and the inner-ring capacitor Cx of the film capacitor are the same, a voltage waveform with equal positive and negative half-cycle amplitude can be measured at the output port of the analog switch, and the direct-current component after low-pass filtering in the output link is 0; when the capacitance value of the film capacitor is increased due to the fact that the film distance of the film capacitor is reduced due to the fact that the pressure of the measured gas is increased, the voltage amplitude of the position of a signal 1 is increased, the analog switch outputs a waveform with a large negative half period amplitude and a small positive half period amplitude, a negative direct current component is obtained after low-pass filtering is carried out in an output link, the negative direct current component is subjected to phase inversion and amplification, and the signal can be adjusted to be within a voltage range which is convenient to measure and cascade other instruments.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the carrier and the GND signal are input into the comparator to obtain the square wave signal, so that the same frequency relation between the square wave signal and the carrier signal can be ensured, the circuit is simple and convenient, other signal generation circuits are not required to be built, the simplicity and the reliability of obtaining the square wave signal are realized, and the cost is further reduced.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the reference capacitance is the outer ring capacitance of the film capacitor.
The material of the upper and lower polar plates of the outer ring capacitor and the inner ring capacitor of the film capacitor is the same, the capacitance value of the outer ring capacitor can be regarded as unchanged (change is very small and can be ignored) under the action of gas pressure, the outer ring capacitor is used as a reference capacitor, and the capacitance change conditions of the inner ring capacitor and the reference capacitor of the film capacitor under the action of temperature can be consistent due to the fact that the material of the capacitor is the same, so that the influence of temperature is reduced or offset, and the detection reliability can be improved.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the outer ring capacitance of the film capacitor is used as the reference capacitance, so that the reliability of vacuum degree detection is improved.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the vacuum degree detection circuit further comprises a first negative feedback module; the input end of the first negative feedback module is connected to the carrier output end of the carrier generation module 10, and the output end of the first negative feedback module is connected to the signal input end of the carrier generation module.
The vacuum degree detection circuit further comprises a first negative feedback module, the input end of the first negative feedback module is connected with the carrier output end of the carrier generation module 10, the output end of the first negative feedback module is connected with the signal input end of the carrier generation module, the actual value and the expected value of the carrier are compared through the first negative feedback module, automatic gain control of the carrier amplitude is achieved, and the purpose of stabilizing the amplitude is achieved.
The vacuum degree detection circuit provided by the embodiment of the invention realizes automatic gain control of the carrier amplitude by arranging the first negative feedback module, and achieves the purpose of stabilizing the amplitude.
Fig. 11 is a second schematic structural diagram of a vacuum detection circuit according to an embodiment of the present invention. As shown in fig. 11, the first negative feedback module includes a first low pass filter 40, a first proportional operation circuit 50 and a PI adjustment module 60 connected in sequence; wherein, an input end of the first low-pass filter 40 is connected to the carrier output end of the carrier generation module 10, and an output end of the PI adjustment module 60 is connected to a signal input end of the carrier generation module 10.
The embodiment of the present invention utilizes a PI (proportional-integral) adjustment module 60 to implement the construction of a first negative feedback module. Before the signal at the carrier output end of the carrier generation module 10 is input to the PI adjustment module 60, the signal needs to be filtered by the first low-pass filter 40 to obtain a dc signal, and then the amplitude of the dc signal is adjusted by the first proportional operation circuit 50 to obtain a signal suitable for processing by the PI adjustment module 60.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the first negative feedback module is constructed by utilizing the first low-pass filter, the first proportional operation circuit and the PI regulation module, so that the reliability of amplitude stabilization processing is improved.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the vacuum degree detection circuit further comprises a second negative feedback module; the input end of the second negative feedback module is connected to the signal output end of the switch circuit 201, and the output end of the second negative feedback module is connected to the signal input end of the carrier generation module.
The vacuum degree detection circuit further comprises a second negative feedback module, the input end of the second negative feedback module is connected with the signal output end of the switch circuit 201, the output end of the first negative feedback module is connected with the signal input end of the carrier generation module, and nonlinear compensation is carried out on the system through the second negative feedback module, so that the output voltage of the output processing module 30 and the measured air pressure are close to or reach a linear relation as far as possible, and the measurement linearity and precision are improved.
The vacuum degree detection circuit provided by the embodiment of the invention improves the linearity and precision of vacuum degree detection by arranging the second negative feedback module.
According to the vacuum degree detection circuit provided by the embodiment of the present invention, as shown in fig. 11, the second negative feedback module includes a second low pass filter 70, a second proportional operation circuit 80 and the PI adjustment module 60, which are connected in sequence; wherein, the input terminal of the second low-pass filter 70 is connected to the signal output terminal of the switch circuit 201.
The embodiment of the present invention further implements the construction of a second negative feedback module using a PI (proportional-integral) adjustment module 60. Before the signal at the signal output end of the switch circuit 201 is input to the PI regulation module 60, the signal needs to be filtered by the second low-pass filter 40 to obtain a dc signal, and then the amplitude of the dc signal is adjusted by the second proportional operation circuit 50 to obtain a signal suitable for processing by the PI regulation module 60.
According to the vacuum degree detection circuit provided by the embodiment of the invention, the second negative feedback module is constructed by utilizing the second low-pass filter, the second proportional operation circuit and the PI regulation module, so that the reliability of nonlinear compensation is improved.
Embodiments of the present invention also provide a vacuum gauge (may also be referred to as a vacuum gauge) including any of the vacuum degree detection circuits in the above embodiments.
Fig. 12 is a schematic flow chart of a vacuum degree detection method according to an embodiment of the present invention. As shown in fig. 12, a vacuum degree detection method provided in an embodiment of the present invention is based on the vacuum degree detection circuit provided in any of the above embodiments, and the method includes:
s1, acquiring output voltage of an output processing module and calibration data of test air pressure based on different test air pressures.
First, calibration data needs to be acquired in advance. The calibration data reflects the relationship of the test air pressure of the output voltage of the output processing module. The calibration data of the output voltage of the output processing module and the test air pressure can be obtained based on different test air pressures.
And S2, acquiring a current measured air pressure value according to the calibration data and the voltage signal output by the output processing module during actual measurement.
And during actual measurement, comparing the voltage signal output during actual measurement with calibration data to obtain a current measured air pressure value.
The vacuum degree detection method provided by the embodiment of the invention realizes simple and convenient acquisition of the vacuum degree value by using data calibration.
Fig. 13 is a schematic structural diagram of an electronic device according to an embodiment of the present invention, and as shown in fig. 8, the electronic device may include: a processor (processor) 810, a communication Interface 820, a memory 830 and a communication bus 840, wherein the processor 810, the communication Interface 820 and the memory 830 communicate with each other via the communication bus 840. The processor 810 may call logic instructions in the memory 830 to perform a vacuum level detection method comprising: based on different test air pressures, acquiring output voltage of the output processing module and calibration data of the test air pressure; and acquiring a current measured air pressure value according to the calibration data and the voltage signal output by the output processing module during actual measurement.
In addition, the logic instructions in the memory 830 may be implemented in software functional units and stored in a computer readable storage medium when the logic instructions are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In another aspect, an embodiment of the present invention further provides a computer program product, where the computer program product includes a computer program, the computer program may be stored on a non-transitory computer-readable storage medium, and when the computer program is executed by a processor, a computer can execute the vacuum degree detection method provided by the foregoing methods, where the method includes: based on different testing air pressures, acquiring the output voltage of the output processing module and calibration data of the testing air pressure; and acquiring a current measured air pressure value according to the calibration data and the voltage signal output by the output processing module during actual measurement.
In another aspect, an embodiment of the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored, where the computer program is implemented to perform the vacuum degree detection method provided by the above methods when executed by a processor, and the method includes: based on different test air pressures, acquiring output voltage of the output processing module and calibration data of the test air pressure; and acquiring a current measured air pressure value according to the calibration data and the voltage signal output by the output processing module during actual measurement.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A vacuum degree detection circuit is characterized by comprising a carrier generation module, a capacitance detection module and an output processing module which are connected in sequence; wherein:
the capacitance detection module comprises a switch circuit, a square wave signal generation circuit and a capacitance bridge formed by a first capacitor, a second capacitor, a reference capacitor and an inner ring capacitor of a film capacitor, wherein the capacitance values of the first capacitor and the second capacitor are the same, and the capacitance values of the reference capacitor and the inner ring capacitor in a vacuum state are the same; the common point of the first capacitor and the inner ring capacitor is connected with a first signal input end of the switch circuit, and the common point of the second capacitor and the reference capacitor is connected with a second signal input end of the switch circuit;
the common point of the first capacitor and the second capacitor is connected with the carrier output end of the carrier generation module, and the common point of the reference capacitor and the inner ring capacitor is grounded; or a common point of the first capacitor and the second capacitor is grounded, and a common point of the reference capacitor and the inner loop capacitor is connected with a carrier output end of the carrier generation module;
the signal output end of the square wave signal generating circuit is connected with the switch enabling port of the switch circuit, the square wave signal generating circuit outputs a square wave signal with the same frequency as the carrier wave output by the carrier wave generating module, and when the square wave signal changes direction, the signal output end of the switch circuit is switched between being communicated with the first signal input end and being communicated with the second signal input end;
the signal output end of the switch circuit is connected with the input end of the output processing module, and the output processing module processes the received signal to obtain a direct current voltage signal reflecting the vacuum degree.
2. The vacuum level detection circuit according to claim 1, wherein the first capacitance, the second capacitance, the reference capacitance, and the inner loop capacitance of the film capacitor have the same capacitance value in a vacuum state.
3. The vacuum level detection circuit according to claim 1, wherein the square wave signal generation circuit includes a comparator; the carrier output end of the carrier generation module is connected with the positive input end of the comparator, and the negative input end of the comparator is grounded; or the carrier output end of the carrier generation module is connected with the negative input end of the comparator, and the positive input end of the comparator is grounded.
4. The vacuum level detection circuit of claim 1, wherein the reference capacitance is an outer loop capacitance of the film capacitor.
5. The vacuum detection circuit of claim 1, further comprising a first negative feedback module; the input end of the first negative feedback module is connected with the carrier output end of the carrier generation module, and the output end of the first negative feedback module is connected with the signal input end of the carrier generation module.
6. The vacuum degree detection circuit according to claim 5, wherein the first negative feedback module comprises a first low-pass filter, a first proportional operation circuit and a PI adjustment module which are connected in sequence; the input end of the first low-pass filter is connected with the carrier output end of the carrier generation module, and the output end of the PI regulation module is connected with the signal input end of the carrier generation module.
7. The vacuum detection circuit of claim 6, further comprising a second negative feedback module; the input end of the second negative feedback module is connected with the signal output end of the switch circuit, and the output end of the second negative feedback module is connected with the signal input end of the carrier generation module.
8. The vacuum degree detection circuit according to claim 7, wherein the second negative feedback module comprises a second low pass filter, a second proportional operation circuit and the PI adjustment module which are connected in sequence; wherein an input terminal of the second low-pass filter is connected to the signal output terminal of the switching circuit.
9. A vacuum gauge comprising the vacuum detection circuit of any one of claims 1to 8.
10. A vacuum degree detection method based on the vacuum degree detection circuit according to any one of claims 1to 8, comprising:
based on different testing air pressures, acquiring the output voltage of the output processing module and calibration data of the testing air pressure;
and acquiring a current measured air pressure value according to the calibration data and the voltage signal output by the output processing module during actual measurement.
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| CN202211275215.5A CN115597767A (en) | 2022-10-18 | 2022-10-18 | Vacuum degree detection circuit, vacuum gauge and vacuum degree detection method |
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| CN202211275215.5A CN115597767A (en) | 2022-10-18 | 2022-10-18 | Vacuum degree detection circuit, vacuum gauge and vacuum degree detection method |
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Effective date of registration: 20230531 Address after: 100020 Jiuxianqiao Road, Chaoyang District, Beijing Applicant after: Beijing Chenjing Electronics Co.,Ltd. Address before: 101200 No. 21, zone 2, Mafang Industrial Park, Zhongguancun Science and Technology Park, Pinggu District, Beijing Applicant before: Beijing chenjing Jingyi Electronics Co.,Ltd. |