CN112504553B - Ionization gauge emission current voltage-controlled constant current control circuit - Google Patents
Ionization gauge emission current voltage-controlled constant current control circuit Download PDFInfo
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- CN112504553B CN112504553B CN202011418371.3A CN202011418371A CN112504553B CN 112504553 B CN112504553 B CN 112504553B CN 202011418371 A CN202011418371 A CN 202011418371A CN 112504553 B CN112504553 B CN 112504553B
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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
- G01L21/30—Vacuum gauges by making use of ionisation effects
- G01L21/32—Vacuum gauges by making use of ionisation effects using electric discharge tubes with thermionic cathodes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L27/00—Testing or calibrating of apparatus for measuring fluid pressure
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
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- Automation & Control Theory (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
The invention relates to a hot cathode ionization vacuum gauge, in particular to an ionization gauge emission current voltage-controlled constant-current control circuit, which comprises an ionization gauge circuit and a bypass current switching branch circuit, wherein the bypass current switching branch circuit comprises an operational amplifier U1, a transistor Q1, a resistor R11 and a capacitor C1, the non-inverting input end of the operational amplifier U1 controls voltage Vref to be used as the voltage-controlled input end for range conversion and control parameter adjustment, an emitter follower containing Qbe forward voltage drop bias is formed by the operational amplifier U1 and the transistor Q1, the collector and emitter currents of the transistor Q1 are equal by the setting of the supply terminal V + and the control voltage Vref of the operational amplifier U1, the operational amplifier U1 makes the emitter potential of the transistor Q1 connected to the inverting input exactly follow the control voltage Vref, the current value determined by the control voltage Vref divided by the resistor R11 and flowing into the ground AG via Qce and the current value determined by the resistor R11 through the cathode to which the collector of the transistor Q1 is connected. The invention has novel and simple structure and is convenient to realize the compensation of any rule of the circuit.
Description
Technical Field
The invention relates to a hot cathode ionization vacuum gauge, in particular to an ionization gauge emission current voltage-controlled constant-current control circuit.
Background
In order to keep good detection sensitivity and precision of the ionization gauge in different measuring ranges, emission current is switched, and under the condition that the potential of a cathode relative to AG is kept stable and unchanged, emission electrons (namely electron current Ie) are quantitatively set by changing the bypass current value of the cathode relative to AG to change the coefficient of the ionization gauge in a grading manner, so that the relative vacuum degree represented by the ion current in the full-pressure measuring range has good linear conversion relation.
As can be seen from FIG. 1, the cathode potential of the hot cathode ionization gauge is determined by the midpoint potential of the filament voltage series equivalent resistors RA and RB; providing a +225V stable accelerating voltage between the gate pair AG; the potential of the cathode to AG is strictly maintained at + 25V.
When the emission current switch K is in an off state, a minimum cathode bypass current value is established by a bypass resistor formed by connecting R01 and R02 in series, and a sampling voltage dividing point VB is formed, so that the emission current value of the vacuum gauge corresponding to the lower limit section of the measured air pressure is set by the minimum bypass current value; when the emission current switch K is closed, the bypass current is suddenly increased to be a newly increased bypass current branch of R11 and is connected with the original bypass branch current of R01 and R02 in series in parallel, and the setting conversion of ten times of emission electrons of the cathode is formed. The air pressure value of the corresponding measuring section is converted according to the gauge coefficient which is correspondingly changed according to different emission current values, and the method can effectively improve the nonlinear distortion of the full-range air pressure detection of the vacuum gauge.
The sudden change increase and decrease of the bypass current inevitably leads to the sudden change of the relative potential of the cathode to the AG, even if the filament closed-loop regulation power supply has a fast response speed, the +25V of the cathode to the AG inevitably occurs an unstable transient process caused by strong disturbance, the transient process is completely finished and then enters the stable state again, and the cathode potential is recovered to be stable and unchanged at + 25V. The unstable transient process caused by range-based switching can make the measured data unstable for a long time and be forced to be lost due to data disconnection. The total switching amount is adopted to be multi-stage stepping switching, although the disturbance intensity can be improved, and the transient time can be shortened. Undoubtedly, it can achieve more accurate and smooth range conversion than using single-level switching, but makes the switching circuit become excessively complex.
The method for compensating the linear deviation of a certain air pressure measuring section by changing the gauge coefficient only belongs to simple position type compensation, and has the advantages that not only is the switching circuit simple, but also the ion flow and the measured gas pressure can be simply and conveniently converted into the conversion coefficient for calculation. Known from the relevant technical literature data of deviation linearity of the conventional range of hot cathode ionization, the measurement region of deviation linearity is in nonlinear deviation, known from the linearization theory, simple proportion compensation is a linear rough compensation of variable trend for nonlinear variables, not only before determining an ideal switching point, but also the error amount of the measurement region of over compensation and under compensation existing before and after the switching point are considered respectively, and single-stage large-proportion transformation compensation is far inferior to the hierarchical compensation of multi-stage subdivision proportion; of course, the optimal compensation is also an algorithmic continuous compensation of the process function. Even if simple stepped shift compensation is adopted, the linear deviation value is changed to start to switch the emission current, the compensation quantity of the linear deviation value is adopted, and the linear deviation value and the compensation quantity are technical parameters to be verified in product design and batch production process parameter selection and even calibration.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides an ionization gauge emission current voltage-controlled constant-current control circuit, which has the following specific technical scheme.
The ionization gauge emission current voltage-controlled constant-current control circuit comprises an ionization gauge circuit and a bypass current switching branch circuit connected with the ionization gauge circuit, wherein the bypass current switching branch circuit is composed of an operational amplifier U1, a transistor Q1, a resistor R11 and a capacitor C1.
Furthermore, the ionization gauge circuit comprises a filament, a resistor RA, a resistor RB, a resistor R1, a resistor R2 and a capacitor Cj, wherein the positive electrode and the negative electrode of the filament are respectively connected with one end of the resistor RA and one end of the resistor RB, and the other end of the resistor RA and the other end of the resistor RB are connected and then connected with one end of the capacitor Cj; one end of the resistor R1 is connected to the other end of the resistor RA, the other end is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the other end of the capacitor Cj and then to ground AG.
Furthermore, the non-inverting input end of the operational amplifier U1 is connected to the control voltage Vref, the inverting input end is connected to one end of the capacitor C1, the other end of the capacitor C1 is connected to one end of the resistor R11 and then grounded AG, the output end of the operational amplifier U1 is connected to the base of the transistor Q1, the positive power supply end of the operational amplifier U1 is connected to the power supply end V +, the negative power supply end of the operational amplifier U1 is grounded AG, the collector of the transistor Q1 is connected to the other end of the resistor RA, the emitter of the transistor Q1 is connected to the other end of the resistor R11, and the other end of the resistor R11 is connected to one end of the capacitor C1.
Furthermore, the non-inverting input terminal of the operational amplifier U1 controls the voltage Vref as the voltage-controlled input terminal for the span conversion and adjustment of the control parameter, the operational amplifier U1 and the transistor Q1 form an emitter follower with Qbe forward voltage drop bias, the collector and emitter currents of the transistor Q1 are equal through the arrangement of the power supply terminal V + of the operational amplifier U1 and the control voltage Vref, the operational amplifier U1 makes the emitter potential of the transistor Q1 connected to the inverting input terminal accurately track and equal to the control voltage Vref, the current value determined by dividing the control voltage Vref by the resistor R11 can only bypass the ground AG through the cathode connected to the collector of the transistor Q1 via Qce and the current value determined by the resistor R11.
Further, the transistor Q1 adopts a high beta tube or even a darlington tube.
The circuit structure of the invention is novel and simple, not only can realize the conversion or continuous adjustment of multi-segment subdivided measuring range, but also can become a simple interface circuit unit for various linearization, optimal parameter experiments and calibration, and can also form a special interface circuit, realize various precise and complex adjustment control through a single chip microcomputer, and realize the optimization of various performances of the ionization vacuum gauge.
Drawings
FIG. 1 is a schematic diagram of a typical equivalent circuit employed in a prior art two-stage transmit current conversion;
fig. 2 is a schematic diagram of the voltage-controlled constant current control circuit of the present invention.
Detailed Description
In order to make the objects, technical solutions and technical effects of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings.
As shown in FIG. 2, the ionization gauge emission current voltage-controlled constant-current control circuit comprises a voltage-controlled constant-current bypass current switching branch consisting of an operational amplifier U1, a transistor Q1, a resistor R11 and a capacitor C1, wherein the voltage-controlled constant-current bypass current switching branch takes a control voltage Vref at the same-direction input end of the operational amplifier U1 as a voltage-controlled input end for range conversion and control parameter adjustment, an emitter follower with Qbe forward voltage drop bias is formed by the operational amplifier U1 and a transistor Q1, under the condition that a power supply end V + and the control voltage Vref of the operational amplifier U1 are reasonably set, a high-beta tube or even a Darlington tube is adopted by the transistor Q1, the collector and emitter currents of the transistor Q1 are approximately equal, and the operational amplifier U1 enables the emitter potential of the transistor Q1 connected to the inverting-phase input end to accurately track and be equal to the control voltage Vref. The current value determined by the control voltage Vref divided by the resistor R11 and can only be bypassed to ground AG by the cathode to which the collector of transistor Q1 is connected via Qce and the current value determined by resistor R11.
Specifically, the circuit comprises an ionization gauge circuit and a bypass current switching branch circuit connected with the ionization gauge circuit, wherein the ionization gauge circuit comprises a filament, a resistor RA, a resistor RB, a resistor R1, a resistor R2 and a capacitor Cj, the positive electrode and the negative electrode of the filament are respectively connected with one end of the resistor RA and one end of the resistor RB, and the other end of the resistor RA and the other end of the resistor RB are connected and then connected with one end of the capacitor Cj; one end of the resistor R1 is connected to the other end of the resistor RA, the other end is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the other end of the capacitor Cj and then to ground AG.
The bypass current switching branch comprises an operational amplifier U1, a transistor Q1, a resistor R11 and a capacitor C1, wherein the non-inverting input end of the operational amplifier U1 is connected with a control voltage Vref, the inverting input end of the operational amplifier U1 is connected with one end of the capacitor C1, the other end of the capacitor C1 is connected with one end of the resistor R11 and then grounded AG, the output end of the operational amplifier U1 is connected with the base of the transistor Q1, the positive power supply end of the operational amplifier U1 is connected with a power supply end V +, the negative power supply end of the operational amplifier U1 is grounded AG, the collector of the transistor Q1 is connected with the other end of the resistor RA, the emitter of the transistor Q1 is connected with the other end of the resistor R11, and the other end of the resistor R11 is connected with one end of the capacitor C1.
The two-stage range switching can be realized only by inputting a high-low level enable control signal at a control voltage Vref end, namely, a cathode emission current value determined by dividing a control voltage Vref by a bypass current value of a resistor R11 is set when a certain control voltage is given, the voltage-controlled range setting circuit not only can realize multi-stage subdivided range conversion or continuous adjustment, but also can be a simple interface circuit unit for various linearization, optimal parameter experiments and calibration, and can also form a special interface circuit, various precise and complex adjustment control is realized through a single chip microcomputer, and the optimization of various performances of the ionization vacuum gauge is realized.
Claims (2)
1. The ionization gauge emission current voltage-controlled constant-current control circuit comprises an ionization gauge circuit and is characterized by further comprising a bypass current switching branch circuit connected with the ionization gauge circuit, wherein the bypass current switching branch circuit consists of an operational amplifier U1, a transistor Q1, a resistor R11 and a capacitor C1;
the ionization gauge circuit comprises a filament, a resistor RA, a resistor RB, a resistor R1, a resistor R2 and a capacitor Cj, wherein the positive electrode and the negative electrode of the filament are respectively connected with one end of the resistor RA and one end of the resistor RB, and the other end of the resistor RA and the other end of the resistor RB are connected and then connected with one end of the capacitor Cj; one end of the resistor R1 is connected with the other end of the resistor RA, the other end of the resistor R2 is connected with one end of the resistor R2, and the other end of the resistor R2 is connected with the other end of the capacitor Cj and then grounded AG;
the non-inverting input end of the operational amplifier U1 is connected with a control voltage Vref, the inverting input end of the operational amplifier U1 is connected with one end of a capacitor C1, the other end of the capacitor C1 is connected with one end of a resistor R11 and then grounded AG, the output end of the operational amplifier U1 is connected with the base electrode of a transistor Q1, the positive power supply end of the operational amplifier U1 is connected with a power supply end V +, the negative power supply end of the operational amplifier U1 is grounded AG, the collector electrode of the transistor Q1 is connected with the other end of a resistor RA, the emitter electrode of a transistor Q1 is connected with the other end of the resistor R11, and the other end of the resistor R11 is connected with one end of the capacitor C1;
the control voltage Vref of the non-inverting input end of the operational amplifier U1 is used as a voltage control input end of a range conversion and adjustment control parameter, the operational amplifier U1 and the transistor Q1 form an emitter follower with Qbe forward voltage drop bias, the collector and emitter currents of the transistor Q1 are equal through the arrangement of the power supply end V + of the operational amplifier U1 and the control voltage Vref, the operational amplifier U1 enables the emitter potential of the transistor Q1 connected to the inverting input end to accurately track and be equal to the control voltage Vref, the current value determined by the control voltage Vref divided by the resistor R11 can only bypass the ground AG through the cathode connected with the collector of the transistor Q1 and the current value determined by the resistor R11 and Qce.
2. The ionization gauge emission current voltage-controlled constant-current control circuit as claimed in claim 1, wherein the transistor Q1 is a high β tube or even a darlington tube.
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Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN87210214U (en) * | 1987-07-15 | 1988-05-18 | 徐建民 | Micro vacuometer power supply for hot cathode ionic gauge |
TW200839208A (en) * | 2007-03-26 | 2008-10-01 | Hon Hai Prec Ind Co Ltd | Ionization gauge |
CN201237545Y (en) * | 2008-07-25 | 2009-05-13 | 德州学院 | Ionization vacuum meter |
CN206363988U (en) * | 2016-11-29 | 2017-07-28 | 武汉光迅科技股份有限公司 | A kind of semiconductor Closed Tube Diffusion vacuum equipment |
US9806685B1 (en) * | 2016-05-13 | 2017-10-31 | Mks Instruments, Inc. | Trans-impedance amplifier with increased dynamic range |
WO2019244826A1 (en) * | 2018-06-18 | 2019-12-26 | 株式会社アルバック | Ionization vacuum gauge and control device |
CN110954265A (en) * | 2019-10-31 | 2020-04-03 | 华北电力大学 | Novel hot cathode ionization vacuum gauge electrical parameter calibration device |
-
2020
- 2020-12-07 CN CN202011418371.3A patent/CN112504553B/en active Active
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN87210214U (en) * | 1987-07-15 | 1988-05-18 | 徐建民 | Micro vacuometer power supply for hot cathode ionic gauge |
TW200839208A (en) * | 2007-03-26 | 2008-10-01 | Hon Hai Prec Ind Co Ltd | Ionization gauge |
CN201237545Y (en) * | 2008-07-25 | 2009-05-13 | 德州学院 | Ionization vacuum meter |
US9806685B1 (en) * | 2016-05-13 | 2017-10-31 | Mks Instruments, Inc. | Trans-impedance amplifier with increased dynamic range |
CN206363988U (en) * | 2016-11-29 | 2017-07-28 | 武汉光迅科技股份有限公司 | A kind of semiconductor Closed Tube Diffusion vacuum equipment |
WO2019244826A1 (en) * | 2018-06-18 | 2019-12-26 | 株式会社アルバック | Ionization vacuum gauge and control device |
CN110954265A (en) * | 2019-10-31 | 2020-04-03 | 华北电力大学 | Novel hot cathode ionization vacuum gauge electrical parameter calibration device |
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