Cold cathode ionization gauge driving acquisition circuit

Abstract

The invention discloses a cold cathode ionization gauge driving acquisition circuit, relates to the field of vacuum measurement, and solves the problems of signal conversion nonlinearity and large ion flow when a gauge tube works at a lower vacuum degree in the existing cold cathode ionization gauge driving acquisition technology. Comprising an ion current logarithmic acquisition circuit used for converting the ion current of the cold cathode ionization gauge into a voltage signal, a current monitoring circuit used for generating a control signal according to the voltage signal, and a voltage-controlled high-voltage driving circuit used for driving the cold cathode ionization gauge according to the control signal. The nonlinear compensation operation conditioning circuit is used for performing nonlinear compensation on the voltage signal according to the control signal to obtain an operation acquisition voltage, and the operation acquisition voltage is used for being input into an acquisition system; the non-linear problem of signal conversion is solved through the non-linear compensation circuit, negative feedback loop control is carried out through the current monitoring circuit and the voltage-controlled high-voltage driving circuit, the driving voltage of a gauge tube is reduced, and the maximum ion current is limited at a low level.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vacuum measurement, more particularly, it relates to a cold cathode ionization gauge driving acquisition circuit. BACKGROUND

[0002] In the principle of a typical cold cathode ionization gauge, due to the initial ionization caused by cosmic rays and field emission, after the gauge tube is started, under the action of electric field and magnetic field, the electrons are limited in a spiral path, so that they have a longer path length and a higher possibility of ionizing the residual gas. When the vacuum degree is high, the discharge ion current and the vacuum degree have a positive linear correspondence relationship, and the gas pressure can be determined by collecting the discharge ion current. Considering the principle and structure of the cold cathode ionization gauge, the following problems exist in the existing cold cathode ionization gauge driving acquisition technology: When the vacuum degree is low (the pressure is greater than 2x10 -3 Pa), due to the decrease of the equivalent resistance of the discharge space, the increase of the ion current gradually slows down, causing the signal to correspond to the nonlinearity of the vacuum degree. And when the pressure is greater than 5x10 -2 Pa, due to excessive reduction of the equivalent resistance, the discharge ion current is critically saturated, and the current changes sharply, which has a higher requirement on the resolution of the acquisition circuit, increasing the acquisition cost. At the same time, since the cold cathode ionization gauge works in a continuous discharge state, an oxide layer will be formed on the surface of the cathode and the anode after long-term use, which needs to be cleaned and maintained before it can restore normal measurement. The severity of oxidation is positively correlated with the size of the discharge ion current. In the existing circuit, the size of the ion current is limited by a series current-limiting resistor, but the sensitivity needs to be limited at high vacuum degree, so the size of the current-limiting resistor should not be too large, which causes the ion current to be too large when the gauge tube works at a low vacuum degree, and the maintenance frequency is high after long-term work, which limits the effective use time.

[0003] Therefore, the present application provides a cold cathode ionization gauge driving acquisition circuit to solve the above problems. SUMMARY

[0004] The purpose of the present application is to provide a cold cathode ionization gauge driving acquisition circuit to solve the problems of signal conversion nonlinearity and ion current being too large when the gauge tube works at a low vacuum degree in the existing cold cathode ionization gauge driving acquisition technology. The present application overcomes the problem of signal conversion nonlinearity through a nonlinear compensation circuit, and reduces the driving voltage of the gauge tube through a current monitoring circuit and a voltage-controlled high-voltage driving circuit for negative feedback loop control, limiting the maximum ion current to a lower level.

[0005] The above-mentioned technical purpose of the present application is achieved through the following technical solutions: including: an ion flow logarithmic acquisition circuit, a current monitoring circuit, a voltage-controlled high-voltage drive circuit and a nonlinear compensation operation conditioning circuit; the ion flow logarithmic acquisition circuit is used to convert the ion flow of the cold cathode ionization gauge into a voltage signal, the current monitoring circuit is used to generate a control signal according to the voltage signal, the voltage-controlled high-voltage drive circuit is used to drive the cold cathode ionization gauge according to the control signal, and the nonlinear compensation operation conditioning circuit is used to perform nonlinear compensation on the voltage signal according to the control signal to obtain an operation acquisition voltage, and the operation acquisition voltage is used to input the acquisition system.

[0006] In one possible embodiment, the ion flow logarithm acquisition circuit includes: operational amplifiers U1 and U2, matching transistors Q1A and Q1D, terminal J1, reference voltage source, potentiometer VR1, capacitor C1, capacitor C2, capacitor C3, capacitor C5, capacitor C6, capacitor C7, filter capacitor C4, resistor R1, resistor R2, resistor R3, resistor R4, resistor R6, current limiting resistor R5, thermistor PTC1; terminal J1 is connected to the ion flow signal, which is respectively connected to the inverting input terminal of the operational amplifier U1 and the collector of the transistor Q1D after passing through the filter capacitor C4 and the current limiting resistor R5, the non-inverting input terminal of the operational amplifier U1 is grounded, the positive and negative power supply terminals of the operational amplifier U1 are connected to the positive and negative power supplies and filtered through capacitors C5 and C6, and the operational amplifier U1 The output end outputs the converted voltage signal, which is divided by resistor R6, potentiometer VR1, and thermistor PTC1 and then added to the base of transistor Q1A. The output end is also connected to the collector of transistor Q1D through capacitor C7. The base of transistor Q1D is grounded, and the emitters of transistor Q1D and transistor Q1A are connected. The reference voltage source is connected to the non-inverting input and inverting input of operational amplifier U2 through resistors R1, R2, and R4. The positive and negative power supply terminals of operational amplifier U2 are connected to the positive and negative power supplies and filtered through capacitors C2 and C3. The output end of operational amplifier U2 is connected to the emitters of transistor Q1D and transistor Q1A through resistor R3. The output end of operational amplifier U2 is respectively connected to its own inverting input and the collector of transistor Q1A through capacitor C1.

[0007] In a possible implementation, the magnitude of the voltage signal is determined by the resistor R6, the potentiometer VR1, the thermistor PTC1, the Boltzmann constant , absolute temperature , electron charge , ion flow signal, and the fixed current flowing through the collector of transistor Q1A.

[0008] In one possible embodiment, the current monitoring circuit includes: an operational amplifier U3A, an operational amplifier U3B, a diode D5, a diode D6, a resistor R14, a resistor R15, a resistor R17, a pull-down resistor R16, a capacitor C9, a capacitor C10, a capacitor C11, and a capacitor C12; the voltage signal output by the ion flow logarithm acquisition circuit is connected to the inverting input terminal of the operational amplifier U3A through the resistor R15, and the inverting input terminal of the operational amplifier U3A is respectively connected to the filter circuit composed of the resistor R14 and the capacitor C10, the diode D5, and the diode D6. D5 and capacitor C9 are connected to their own output terminals, the non-inverting input terminal of the operational amplifier U3A is grounded through resistor R17, the output terminal of the operational amplifier U3A is connected to the non-inverting output terminal of the operational amplifier U3B through diode D6, the non-inverting input terminal of the operational amplifier U3B is also grounded through resistor R16, the inverting output terminal of the operational amplifier U3B is connected to its own output terminal, the positive and negative power supply terminals of the operational amplifier U3B are connected to the positive and negative power supplies and are grounded through capacitors C11 and C12, and the output terminal of the operational amplifier U3B outputs a control signal.

[0009] In one possible implementation, the cathode of diode D5 is connected to the inverting input terminal of operational amplifier U3A, and the anode is connected to the output terminal of operational amplifier U3A; the cathode of diode D6 is connected to the output terminal of operational amplifier U3A, and the anode is connected to the non-inverting output terminal of operational amplifier U3B.

[0010] In one possible embodiment, a voltage-controlled high-voltage drive circuit includes: a voltage regulating circuit, a Royer push-pull self-excitation circuit and a voltage-doubling rectifier circuit; the voltage regulating circuit outputs a DC voltage according to a control signal output by a current monitoring circuit; the Royer push-pull self-excitation circuit inverts the DC voltage and outputs an AC high voltage through a transformer; and the voltage-doubling rectifier circuit adjusts the AC high voltage to a DC high voltage output.

[0011] In one possible implementation, the voltage regulating circuit includes: an adjustable voltage regulator U4, a potentiometer VR2, a resistor R22, a resistor R18, and a capacitor C13. The control signal output by the current monitoring circuit is connected to the adjustment end of the adjustable voltage regulator U4 via the potentiometer VR2, the resistor R22, and the resistor R18. The input end of the adjustable voltage regulator U4 is connected to the power supply and filtered by the capacitor C13. The output end of the adjustable voltage regulator U4 outputs a DC voltage, and the output end is connected to the connection point of the resistor R22 and the resistor R18; R The oyer push-pull self-excitation circuit includes: resistor R23, electrolytic capacitor C15, electrolytic capacitor C19, resistor R19, resistor R24, capacitor C20, capacitor C14, capacitor C17, transistor Q1, transistor Q2 and transformer T1, the transformer includes: a first transformer primary side, a second transformer primary side and a transformer secondary side, the DC voltage output by the adjustable voltage regulator U4 is grounded through the electrolytic capacitor C15 and connected to the center tap of the first transformer primary side, the DC voltage output by the adjustable voltage regulator U4 is connected to the center tap of the first transformer primary side through the resistor R23, capacitor C20 and electrolytic capacitor C19 are connected to the center tap of the primary side of the second transformer. The opposite-name terminals of the primary side of the first transformer are connected to the same-name terminals of the primary side of the second transformer through transistor Q1 and resistor R19. The same-name terminals of the primary side of the first transformer are connected to the opposite-name terminals of the primary side of the second transformer through transistor Q2 and resistor R24. The collector of transistor Q1 is connected to its own base through capacitor C14. The collector of transistor Q2 is connected to its own base through capacitor C17. The emitters of transistors Q1 and Q2 are connected. The transformer secondary side is connected to the ground, and the transformer outputs AC high voltage. The voltage doubling rectifier circuit includes: a high-voltage capacitor C16, a high-voltage capacitor C18, a high-voltage diode D1, and a high-voltage diode D2. The AC high voltage output from the transformer secondary side is connected in series with the high-voltage capacitor C16 and then in parallel with the high-voltage diode D1. The high-voltage diode D2 is connected in series with the high-voltage diode D1 and then in parallel with the high-voltage capacitor C18. The high-voltage capacitor C18 is connected in parallel with the load resistor R25. One end of the load resistor R25 passes through the current limiting resistor R20 and the current limiting resistor R21 to output DC high voltage.

[0012] In one possible implementation, the nonlinear compensation operation conditioning circuit includes: an operational amplifier U2B, an operational amplifier U2A, a diode D7, a diode D8, a diode D9, a resistor R25, a resistor R26, a resistor R27, a resistor R28, a resistor R29, a resistor R30, a resistor R31, a resistor R32, a resistor R33, a resistor R34, a resistor R35, a resistor R36, a capacitor C20, a capacitor C21, and a capacitor C22; the output of the ion flow logarithm acquisition circuit is connected to the inverting input terminal of the operational amplifier U2B through the resistor R35, the non-inverting input terminal of the operational amplifier U2B is grounded through the resistor R36, the positive and negative power supply terminals of the operational amplifier U2B are connected to the positive and negative power supplies and connected through the capacitors C22 and Capacitor C21 is filtered, and the output of the operational amplifier U2B is connected to its own inverting input terminal through resistor R33. Resistor R33 is connected in parallel with capacitor C20. Capacitor C20 is connected in parallel with diode D9. The cathode of diode D9 is connected to the reference voltage source through resistor R31. The output of the operational amplifier U2B is connected to the inverting input terminal of the operational amplifier U2A through resistor R34. The control signal is connected to the inverting input terminal of the operational amplifier U2A through the nonlinear compensation branch. The inverting input terminal of the operational amplifier U2A is connected to its own output terminal through parallel resistors R27 and diode D7. The non-inverting input terminal of the operational amplifier U2A is grounded through resistor R32. The output terminal of the operational amplifier U2A outputs the operational acquisition voltage for inputting into the acquisition system.

[0013] In one possible implementation, the nonlinear compensation branch includes: a reference voltage source, a resistor R25, a resistor R28, a diode D8, a resistor R26, a resistor R29, a resistor R30, and a potentiometer VR3. The reference voltage source is connected to the inverting input terminal of the operational amplifier U2A through the resistor R25, the resistor R28, the resistor R29, and the resistor R30. The connection point between the resistor R28 and the resistor R29 is connected to the control signal output by the current monitoring circuit. The connection point between the resistor R25 and the resistor R28 is connected to the inverting input terminal of the operational amplifier U2A through the diode D8, the resistor R26, and the potentiometer VR3.

[0014] In one possible implementation, when the ion current signal is less than the threshold, the control signal voltage output by the current monitoring circuit is Maintained at 0V, at this time only the signal output by operational amplifier U2B enters operational amplifier U2A, and the output voltage of operational amplifier U2A is: , is the output voltage of the operational amplifier U2B, which is related to the size of the ion current. When the circuit enters the constant current mode through the negative feedback loop composed of the current monitoring circuit and the voltage-controlled high-voltage drive circuit, the voltage signal output by the ion current logarithmic acquisition circuit will be maintained at 0V. The output fixed value is included in the addition operation, and the control signal voltage output by the current monitoring circuit Starting from 0V and changing towards negative voltage, before diode D8 turns on, only resistors R29 and R30 participate in the feedback operation. At this time, the voltage output by operational amplifier U2A is: , the control signal voltage After diode D8 is turned on, resistor R26 and potentiometer VR3 also participate in the feedback operation. At this time, the voltage output by operational amplifier U2A is: ,in is the forward voltage drop of diode D7, is the voltage applied to the cathode of diode D7.

[0015] Compared with the existing technology, the present application has the following beneficial effects: by introducing a nonlinear compensation circuit, the nonlinear problem in the signal conversion process is effectively solved; at the same time, a negative feedback loop is constructed using a current monitoring circuit and a voltage-controlled high-voltage drive circuit, which reduces the driving voltage of the cold cathode ionization gauge and limits the maximum ion current to a lower level; the cold cathode ionization gauge drive acquisition circuit provided by the present application can significantly reduce the acquisition difficulty, maintenance frequency and power consumption of the cold cathode ionization gauge, while improving reliability, measurement accuracy and measurement upper limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings: Figure 1 A circuit schematic diagram of a cold cathode ionization gauge drive acquisition circuit provided in an embodiment of the present application; Figure 2 A circuit diagram of an ion current logarithm acquisition circuit provided in an embodiment of the present application; Figure 3 A circuit diagram of a current monitoring circuit provided in an embodiment of the present application; Figure 4 A circuit diagram of a voltage-controlled high-voltage drive circuit provided in an embodiment of the present application; Figure 5 This is a circuit diagram of the nonlinear compensation operation conditioning circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0017] Hereinafter, the terms "include" or "may include" as used in various embodiments of the present application indicate the presence of the claimed function, operation, or element, and do not limit the addition of one or more functions, operations, or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their cognates are intended only to indicate specific features, numbers, steps, operations, elements, components, or combinations of the foregoing, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing or the possibility of adding one or more features, numbers, steps, operations, elements, components, or combinations of the foregoing.

[0018] It should be noted that when a component is described as being “connected” to or “connected to” another component, the first component may be directly connected to the second component, and a third component may be “connected” between the first and second components. Conversely, when a component is described as being “directly connected” to or “directly connected to” another component, it can be understood that there is no third component between the first and second components.

[0019] The terms used in the various embodiments of the present application are only used for the purpose of describing specific embodiments and are not intended to limit the various embodiments of the present application. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise specified, all terms used herein (including technical terms and scientific terms) have the same meaning as those generally understood by those skilled in the art to which the various embodiments of the present application belong. Terms (such as those defined in generally used dictionaries) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in the various embodiments of the present application.

[0020] In order to make the objectives, technical solutions and advantages of this application more clear, the present application is further described in detail below in conjunction with examples and drawings. The schematic implementation methods of this application and their descriptions are only used to explain this application and are not intended to limit this application.

[0021] See Figure 1 As shown, Figure 1The circuit principle diagram of the cold cathode ion gauge driving acquisition circuit provided by the embodiment of the application is provided. The cold cathode ion gauge driving acquisition circuit comprises an ion current logarithmic acquisition circuit, a current monitoring circuit, a voltage-controlled high-voltage driving circuit and a nonlinear compensation operation conditioning circuit. The ion current logarithmic acquisition circuit is used for converting the ion current of the cold cathode ion gauge into a voltage signal. The current monitoring circuit is used for generating a control signal according to the voltage signal. The voltage-controlled high-voltage driving circuit is used for driving the cold cathode ion gauge according to the control signal. The nonlinear compensation operation conditioning circuit is used for performing nonlinear compensation on the voltage signal according to the control signal to obtain an operation acquisition voltage. The operation acquisition voltage is used for inputting into an acquisition system.

[0022] The improvement of the application is that the nonlinear problem in the ion current signal conversion process of the ion gauge is effectively solved by introducing the nonlinear compensation circuit. Meanwhile, the negative feedback loop is constructed by using the current monitoring circuit and the voltage-controlled high-voltage driving circuit, the driving voltage of the cold cathode ion gauge is reduced, and the maximum ion current is limited at a lower level. The cold cathode ion gauge driving acquisition circuit provided by the application can significantly reduce the acquisition difficulty, maintenance frequency and power consumption of the driving circuit of the cold cathode ion gauge, and improve the reliability, measurement accuracy and upper limit of measurement.

[0023] Please refer to Figure 2 , as shown in Figure 2A circuit diagram of an ion flow logarithm acquisition circuit provided in an embodiment of the present application. In one possible implementation, the ion flow logarithm acquisition circuit includes: operational amplifiers U1 and U2, matching transistors Q1A and Q1D, terminal J1, a reference voltage source, a potentiometer VR1, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C5, a capacitor C6, a capacitor C7, a filter capacitor C4, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R6, a current limiting resistor R5, and a thermistor PTC1; the terminal J1 is connected to the ion flow signal, which is respectively connected to the inverting input terminal of the operational amplifier U1 and the collector of the transistor Q1D after passing through the filter capacitor C4 and the current limiting resistor R5, the non-inverting input terminal of the operational amplifier U1 is grounded, the positive and negative power supply terminals of the operational amplifier U1 are connected to the positive and negative power supplies and filtered through the capacitors C5 and C6, and the operational amplifier U1 is The output end outputs the converted voltage signal, which is divided by resistor R6, potentiometer VR1, and thermistor PTC1 and then added to the base of transistor Q1A. The output end is also connected to the collector of transistor Q1D through capacitor C7. The base of transistor Q1D is grounded, and the emitters of transistor Q1D and transistor Q1A are connected. The reference voltage source is connected to the non-inverting input and inverting input of operational amplifier U2 through resistors R1, R2, and R4. The positive and negative power supply terminals of operational amplifier U2 are connected to the positive and negative power supplies and filtered through capacitors C2 and C3. The output end of operational amplifier U2 is connected to the emitters of transistor Q1D and transistor Q1A through resistor R3. The output end of operational amplifier U2 is respectively connected to its own inverting input and the collector of transistor Q1A through capacitor C1.

[0024] Furthermore, the magnitude of the voltage signal is determined by the resistor R6, the potentiometer VR1, the thermistor PTC1, the Boltzmann constant , absolute temperature , electron charge , ion flow signal, and the fixed current flowing through the collector of transistor Q1A.

[0025] Specifically, the main body of the ion flow logarithmic acquisition circuit is a logarithmic amplifier circuit with differential proportional operation. The converted voltage signal Log_Out is output through the output terminal of operational amplifier U1. After operational amplifiers U1 and U2 establish deep negative feedback, the output is divided by resistor R6, potentiometer VR1, and thermistor PTC1 and then applied to the base of transistor Q1A. At this time, the base voltage of Q1A is: ,in, It represents the voltage signal output by the ion current logarithm acquisition circuit. Under the action of the -5V reference voltage source and resistors R1, R2, and R4, a fixed current will flow through the collector of transistor Q1A. The current value is: , when the resistors R1 and R2 are 47.5kΩ and the resistor R4 is 2.49kΩ, =100uA. According to the Shockley diode equation, the base-to-emitter voltage of transistor Q1A is: ,in is the Boltzmann constant, is the electron charge, is the absolute temperature, is the reverse saturation current of transistor Q1A, which is affected by temperature. At the same time, the ion flow signal Current_Signal input from terminal J1 passes through filter capacitor C4 and current limiting resistor R5 and flows through the collector of transistor Q1D. At this time, the base-to-emitter voltage of transistor Q1D is: ,in is the ion flow signal, the direction is outflow, is the reverse saturation current of transistor Q1D. Since transistors Q1A and Q1D are matched transistors, they can be regarded as Since the base of transistor Q1D is at ground potential, and the emitters of transistor Q1A and transistor Q1D are at the same potential, the relationship can be obtained: , is the base voltage of transistor Q1A, and then we get: For thermistor PTC1, a 1kΩ, 3500 PPM positive temperature coefficient (PTC) resistor is chosen to essentially offset the effects of temperature. Observing the expression, since all other parameters are constant, the output is proportional only to the logarithm of the input ion current. Adjusting the voltage divider ratio with potentiometer VR1 changes the output slope. Operational amplifier U1 can use the OPA928DR, and operational amplifier U2 can use the OP07. The positive and negative power supplies are +15V and -15V, respectively.

[0026] See Figure 3 As shown, Figure 3A circuit diagram of a current monitoring circuit provided in an embodiment of the present application. In one possible embodiment, the current monitoring circuit includes: an operational amplifier U3A, an operational amplifier U3B, a diode D5, a diode D6, a resistor R14, a resistor R15, a resistor R17, a pull-down resistor R16, a capacitor C9, a capacitor C10, a capacitor C11, and a capacitor C12; the voltage signal output by the ion flow logarithm acquisition circuit is connected to the inverting input terminal of the operational amplifier U3A through the resistor R15, and the inverting input terminal of the operational amplifier U3A is respectively connected to the filter circuit composed of the resistor R14 and the capacitor C10, the diode D5, and the diode D6. D5 and capacitor C9 are connected to their own output terminals, the non-inverting input terminal of the operational amplifier U3A is grounded through resistor R17, the output terminal of the operational amplifier U3A is connected to the non-inverting output terminal of the operational amplifier U3B through diode D6, the non-inverting input terminal of the operational amplifier U3B is also grounded through resistor R16, the inverting output terminal of the operational amplifier U3B is connected to its own output terminal, the positive and negative power supply terminals of the operational amplifier U3B are connected to the positive and negative power supplies and are grounded through capacitors C11 and C12, and the output terminal of the operational amplifier U3B outputs a control signal.

[0027] Furthermore, the cathode of the diode D5 is connected to the inverting input terminal of the operational amplifier U3A, and the anode is connected to the output terminal of the operational amplifier U3A. The cathode of the diode D6 is connected to the output terminal of the operational amplifier U3A, and the anode is connected to the non-inverting output terminal of the operational amplifier U3B.

[0028] Specifically, the current monitoring circuit is an amplifier circuit with a zero-crossing response. The circuit's input is the output Log_Out of the ion current logarithm acquisition circuit. The output formula for the ion current logarithm acquisition circuit shows that when the ion current signal is less than 100uA, the circuit's input value is negative, diode D5 will conduct, and the output of operational amplifier U3A will remain at the conduction voltage of diode D5. The voltage on the cathode of diode D6 is greater than the positive electrode, making diode D6 unable to conduct. The non-inverting input of operational amplifier U3B will be maintained at a low level under the action of pull-down resistor R16, and the voltage follower circuit formed by operational amplifier U3B will output a 0V voltage. When the ion current signal is greater than 100uA, the circuit input value is positive. Due to the open-loop gain of operational amplifier U3A, operational amplifier U3A will quickly output a negative voltage, causing diode D6 to conduct. Then, the voltage follower circuit outputs a negative voltage until the output reaches the negative power supply voltage of -15V. The circuit outputs a control signal HV_Adj as the input of the voltage-controlled high-voltage drive circuit, forming a negative feedback loop. The operational amplifier U3A and the operational amplifier U3B can use LM258, and the diode D5 and the diode D6 can use MMBD914LT3G.

[0029] See Figure 4 As shown, Figure 4This is a circuit diagram of a voltage-controlled high-voltage drive circuit provided in an embodiment of the present application. In one possible implementation, the voltage-controlled high-voltage drive circuit includes: a voltage-regulating circuit, a Royer push-pull self-excitation circuit, and a voltage-doubling rectifier circuit; the voltage-regulating circuit outputs a DC voltage based on a control signal output by a current monitoring circuit; the Royer push-pull self-excitation circuit inverts the DC voltage and outputs an AC high voltage through a transformer; and the voltage-doubling rectifier circuit adjusts the AC high voltage to a DC high voltage output.

[0030] Furthermore, the voltage regulating circuit includes: an adjustable voltage regulator U4, a potentiometer VR2, a resistor R22, a resistor R18, and a capacitor C13. The control signal output by the current monitoring circuit is connected to the adjustment end of the adjustable voltage regulator U4 via the potentiometer VR2, the resistor R22, and the resistor R18. The input end of the adjustable voltage regulator U4 is connected to the power supply and filtered by the capacitor C13. The output end of the adjustable voltage regulator U4 outputs a DC voltage, and the output end is connected to the connection point of the resistor R22 and the resistor R18. Royer push The self-excitation circuit includes: resistor R23, electrolytic capacitor C15, electrolytic capacitor C19, resistor R19, resistor R24, capacitor C20, capacitor C14, capacitor C17, transistor Q1, transistor Q2 and transformer T1. The transformer includes: a first transformer primary side, a second transformer primary side and a transformer secondary side. The DC voltage output by the adjustable voltage regulator U4 is grounded through the electrolytic capacitor C15 and connected to the center tap of the first transformer primary side. The DC voltage output by the adjustable voltage regulator U4 is connected to the center tap of the first transformer primary side through the resistor R23. , capacitor C20 and electrolytic capacitor C19 are connected to the center tap of the primary side of the second transformer, the opposite-name terminals of the primary side of the first transformer are connected to the same-name terminals of the primary side of the second transformer through transistor Q1 and resistor R19, the same-name terminals of the primary side of the first transformer are connected to the opposite-name terminals of the primary side of the second transformer through transistor Q2 and resistor R24, the collector of transistor Q1 is connected to its own base through capacitor C14, the collector of transistor Q2 is connected to its own base through capacitor C17, and the emitters of transistors Q1 and Q2 are connected Grounded, the secondary side of the transformer outputs AC high voltage; the voltage doubling rectifier circuit includes: a high-voltage capacitor C16, a high-voltage capacitor C18, a high-voltage diode D1, and a high-voltage diode D2. The AC high voltage output from the secondary side of the transformer is connected in series with the high-voltage capacitor C16 and then in parallel with the high-voltage diode D1. The high-voltage diode D2 is connected in series with the high-voltage diode D1 and then in parallel with the high-voltage capacitor C18. The high-voltage capacitor C18 is connected in parallel with the load resistor R25. One end of the load resistor R25 passes through the current limiting resistor R20 and the current limiting resistor R21 to output DC high voltage.

[0031] Specifically, the voltage-controlled high-voltage driving circuit for driving the cold cathode ionization gauge is mainly composed of a typical Royer push-pull self-oscillation circuit, a voltage doubler rectifier circuit and a voltage regulating circuit. The Royer circuit principle is to realize the push-pull self-oscillation of the circuit by the current saturation of the triode and the auxiliary winding of the transformer magnetic core saturation, and then to output high voltage through the transformer after the input DC voltage is inverted. The output voltage of the secondary side of the transformer is mainly determined by the input DC voltage and the turns ratio of the transformer. The output voltage is output as DC high voltage after passing through the voltage doubler rectifier circuit composed of high-voltage capacitor C16, high-voltage capacitor C18, high-voltage diode D1 and high-voltage diode D2, and is used to drive the cold cathode pin of the cold cathode ionization gauge. The resistor R25 in the rear stage is used as a load resistor, and the resistors R20 and R21 are used as current limiting resistors. The input DC voltage of the transformer is output by the voltage regulating circuit composed of the adjustable voltage stabilizer U4. The adjustable voltage stabilizer U4 can be LM317T, and the output voltage of the voltage regulating circuit is obtained from the chip manual as follows: , The voltage value of the control signal HV_Adj output by the current monitoring circuit can be seen as follows: since the resistors R1, R5 and the potentiometer VR1 are constant values, the output voltage of the voltage regulating circuit is only determined by the output of the current monitoring circuit. When the current monitoring circuit monitors that the ion current signal is greater than 100uA, the negative feedback loop will adjust the size of the output high voltage, so that the ion current signal remains at about 100uA, thereby realizing the current limiting protection function. The triodes Q1 and Q2 can be CXT3019, the transformer T1 can be Trans-RM10, and the diodes D1 and D2 can be HV5.

[0032] Please refer to Figure 5 as shown, Figure 5A circuit diagram of a nonlinear compensation operation conditioning circuit provided in an embodiment of the present application. In one possible implementation, the nonlinear compensation operation conditioning circuit includes: an operational amplifier U2B, an operational amplifier U2A, a diode D7, a diode D8, a diode D9, a resistor R25, a resistor R26, a resistor R27, a resistor R28, a resistor R29, a resistor R30, a resistor R31, a resistor R32, a resistor R33, a resistor R34, a resistor R35, a resistor R36, a capacitor C20, a capacitor C21, and a capacitor C22; the output of the ion flow logarithm acquisition circuit is connected to the inverting input terminal of the operational amplifier U2B through a resistor R35, the non-inverting input terminal of the operational amplifier U2B is grounded through a resistor R36, the positive and negative power supply terminals of the operational amplifier U2B are connected to the positive and negative power supplies and connected through capacitors C22 and Capacitor C21 is filtered, and the output of the operational amplifier U2B is connected to its own inverting input terminal through resistor R33. Resistor R33 is connected in parallel with capacitor C20. Capacitor C20 is connected in parallel with diode D9. The cathode of diode D9 is connected to the reference voltage source through resistor R31. The output of the operational amplifier U2B is connected to the inverting input terminal of the operational amplifier U2A through resistor R34. The control signal is connected to the inverting input terminal of the operational amplifier U2A through the nonlinear compensation branch. The inverting input terminal of the operational amplifier U2A is connected to its own output terminal through parallel resistors R27 and diode D7. The non-inverting input terminal of the operational amplifier U2A is grounded through resistor R32. The output terminal of the operational amplifier U2A outputs the operational acquisition voltage for inputting into the acquisition system.

[0033] Furthermore, the nonlinear compensation branch includes: a reference voltage source, a resistor R25, a resistor R28, a diode D8, a resistor R26, a resistor R29, a resistor R30, and a potentiometer VR3. The reference voltage source is connected to the inverting input terminal of the operational amplifier U2A through the resistor R25, the resistor R28, the resistor R29, and the resistor R30. The connection point between the resistor R28 and the resistor R29 is connected to the control signal output by the current monitoring circuit. The connection point between the resistor R25 and the resistor R28 is connected to the inverting input terminal of the operational amplifier U2A through the diode D8, the resistor R26, and the potentiometer VR3.

[0034] Furthermore, when the ion current signal is less than the threshold, the control signal voltage output by the current monitoring circuit is Maintained at 0V, at this time only the signal output by operational amplifier U2B enters operational amplifier U2A, and the output voltage of operational amplifier U2A is: , is the output voltage of the operational amplifier U2B, which is related to the size of the ion current. When the circuit enters the constant current mode through the negative feedback loop composed of the current monitoring circuit and the voltage-controlled high-voltage drive circuit, the voltage signal output by the ion current logarithmic acquisition circuit will be maintained at 0V. The output fixed value is included in the addition operation, and the control signal voltage output by the current monitoring circuit Starting from 0V and changing towards negative voltage, before diode D8 turns on, only resistors R29 and R30 participate in the feedback operation. At this time, the voltage output by operational amplifier U2A is: , the control signal voltage After diode D8 is turned on, resistor R26 and potentiometer VR3 also participate in the feedback operation. At this time, the voltage output by operational amplifier U2A is: ,in is the forward voltage drop of diode D7, is the voltage applied to the cathode of diode D7.

[0035] Specifically, the main body of the nonlinear compensation operation conditioning circuit consists of a two-stage reverse addition proportional operation circuit, followed by an output voltage clamp and ADC acquisition voltage clamp protection circuit. The first-stage reverse addition proportional operation circuit composed of the operational amplifier U2B performs reverse addition proportional amplification on the voltage signal Log_Out output by the ion flow logarithm acquisition circuit and the 5V reference voltage source. The output voltage of the operational amplifier U2B is: , After passing through the feedback resistor R34, it enters the second stage reverse addition proportional operation circuit composed of the operational amplifier U2A. The input of the second stage proportional operation circuit is In addition to the branch, there is a nonlinear compensation branch consisting of a 5V reference voltage source, resistor R25, resistor R28, diode D8, resistor R26, resistor R29, resistor R30, and potentiometer VR3. The input of the nonlinear compensation branch is the control signal HV_Adj output by the current monitoring circuit. Analysis of the input signal and circuit structure shows that when the input ion current signal is less than 100uA (threshold), the control signal voltage output by the current monitoring circuit Will remain at 0V, and the only thing actually participating in the second-level operation is The signal of the branch, that is, the output voltage at this time is only related to the size of the ion flow. At this time, the output voltage of the operational amplifier U2A is: When the circuit enters the constant current mode through the negative feedback loop formed by the current monitoring circuit and the voltage-controlled high-voltage drive circuit, the output voltage of the ion current logarithmic acquisition circuit will remain at 0V and will not change. A fixed value will be output to participate in the addition operation. At this time, the output voltage has nothing to do with the size of the ion flow, but is only related to the control signal. The nonlinear compensation branch realizes nonlinear compensation through the voltage divider circuit composed of 5V reference voltage source, resistor R25, resistor R28, diode D8, feedback resistor R26, and potentiometer VR3. The specific process is: when the circuit enters the constant current mode, the control signal voltage Starting from 0V and changing towards negative voltage, the voltage applied to the cathode of diode D7 is: , the anode voltage of diode D7 is 0V before it is turned on. Before the voltage divider circuit turns on diode D7, only resistors R29 and R30 participate in the feedback operation. At this time, the output of the circuit is: , when the control signal voltage After diode D7 is turned on, resistor R26 and potentiometer VR3 also begin to participate in the feedback operation. At this time, the output of the circuit is: ,in = is the conduction voltage drop of diode D7. The formula shows that the conduction of diode D7 increases the feedback coefficient of the nonlinear compensation branch. The values ​​of resistors R25 and R28 control the onset of nonlinear compensation, and potentiometer VR3 sets the compensation ratio, thereby achieving nonlinear compensation of the signal. After compensation, the circuit outputs the operational acquisition voltage ColdCathodeANL OUT, which enters the acquisition system to drive and acquire the cold cathode ionization gauge. Operational amplifiers U2B and U2A can use the LM258.

[0036] It is understandable that when the circuit enters the constant current mode, the control signal voltage The reason why it changes from 0V to negative voltage is that the current monitoring circuit is an amplifier circuit with zero-crossing response. When the ion current is greater than 100uA, the output of the ion current logarithmic acquisition circuit (that is, the input of the current monitoring circuit) will cross from negative value to positive value. According to the output characteristics of the current monitoring circuit, the response result will change from 0V to negative voltage direction.

[0037] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cold cathode ionization gauge drive acquisition circuit, characterized in that: include: Ion flow logarithmic acquisition circuit, current monitoring circuit, voltage-controlled high-voltage drive circuit and nonlinear compensation operation conditioning circuit; The ion flow logarithmic acquisition circuit is used to convert the ion flow of the cold cathode ionization gauge into a voltage signal, the current monitoring circuit is used to generate a control signal based on the voltage signal, the voltage-controlled high-voltage drive circuit is used to drive the cold cathode ionization gauge according to the control signal, and the nonlinear compensation operation conditioning circuit is used to perform nonlinear compensation on the voltage signal according to the control signal to obtain an operation acquisition voltage, and the operation acquisition voltage is used to input into the acquisition system.

2. The cold cathode ionization gauge drive acquisition circuit according to claim 1, characterized in that: The ion flow logarithm acquisition circuit includes: operational amplifiers U1 and U2, matching transistors Q1A and Q1D, terminal J1, reference voltage source, potentiometer VR1, capacitor C1, capacitor C2, capacitor C3, capacitor C5, capacitor C6, capacitor C7, filter capacitor C4, resistor R1, resistor R2, resistor R3, resistor R4, resistor R6, current limiting resistor R5, and thermistor PTC1; The terminal J1 receives the ion flow signal, and is connected to the inverting input terminal of the operational amplifier U1 and the collector of the transistor Q1D respectively after passing through the filtering capacitor C4 and the current limiting resistor R5. The non-inverting input terminal of the operational amplifier U1 is grounded. The positive and negative power supply terminals of the operational amplifier U1 are connected to the positive and negative power supplies and filtered through the capacitors C5 and C6. The output terminal of the operational amplifier U1 outputs the converted voltage signal, and the output terminal is applied to the base of the transistor Q1A after voltage division through the resistor R6, the potentiometer VR1, and the thermistor PTC1. The output terminal is also connected to the collector of the transistor Q1D through the capacitor C7. The base of the transistor Q1D is grounded, and the emitters of the transistor Q1D and the transistor Q1A are connected. The reference voltage source is connected to the non-inverting input and inverting input of the operational amplifier U2 via resistors R1, R2, and R4. The positive and negative power supply terminals of the operational amplifier U2 are connected to the positive and negative power supplies and filtered through capacitors C2 and C3. The output terminal of the operational amplifier U2 is connected to the emitters of transistors Q1D and Q1A via resistor R3. The output terminal of the operational amplifier U2 is connected to its own inverting input and the collector of transistor Q1A via capacitor C1.

3. The cold cathode ionization gauge drive acquisition circuit according to claim 2, characterized in that: The magnitude of the voltage signal is determined by the resistor R6, the potentiometer VR1, the thermistor PTC1, the Boltzmann constant , absolute temperature , electron charge , ion flow signal, and the fixed current flowing through the collector of transistor Q1A.

4. The cold cathode ionization gauge drive acquisition circuit according to claim 1, characterized in that: The current monitoring circuit includes: an operational amplifier U3A, an operational amplifier U3B, a diode D5, a diode D6, a resistor R14, a resistor R15, a resistor R17, a pull-down resistor R16, a capacitor C9, a capacitor C10, a capacitor C11, and a capacitor C12; The voltage signal output by the ion flow logarithm acquisition circuit is connected to the inverting input terminal of the operational amplifier U3A through a resistor R15. The inverting input terminal of the operational amplifier U3A is connected to its own output terminal through a filter circuit composed of a resistor R14 and a capacitor C10, a diode D5, and a capacitor C9. The non-inverting input terminal of the operational amplifier U3A is grounded through a resistor R17. The output terminal of the operational amplifier U3A is connected to the non-inverting output terminal of the operational amplifier U3B through a diode D6. The non-inverting input terminal of the operational amplifier U3B is also grounded through a resistor R16. The inverting output terminal of the operational amplifier U3B is connected to its own output terminal. The positive and negative power supply terminals of the operational amplifier U3B are connected to the positive and negative power supplies and are grounded through capacitors C11 and C12. The output terminal of the operational amplifier U3B outputs a control signal.

5. The cold cathode ionization gauge drive acquisition circuit according to claim 4, characterized in that: The cathode of the diode D5 is connected to the inverting input terminal of the operational amplifier U3A, and the anode is connected to the output terminal of the operational amplifier U3A. The cathode of the diode D6 is connected to the output terminal of the operational amplifier U3A, and the anode is connected to the non-inverting output terminal of the operational amplifier U3B.

6. The cold cathode ionization gauge drive acquisition circuit according to claim 1, characterized in that: The voltage-controlled high-voltage driving circuit includes: a voltage regulating circuit, a Royer push-pull self-excitation circuit and a voltage doubling rectifier circuit; The voltage regulating circuit outputs a DC voltage according to the control signal output by the current monitoring circuit; The Royer push-pull self-excitation circuit inverts the DC voltage and outputs AC high voltage through a transformer; The voltage doubler rectifier circuit adjusts the AC high voltage to a DC high voltage output.

7. The cold cathode ionization gauge drive acquisition circuit according to claim 6, characterized in that: The voltage regulating circuit includes: an adjustable voltage regulator U4, a potentiometer VR2, a resistor R22, a resistor R18, and a capacitor C13. The control signal output by the current monitoring circuit is connected to the adjustment end of the adjustable voltage regulator U4 via the potentiometer VR2, the resistor R22, and the resistor R18. The input end of the adjustable voltage regulator U4 is connected to the power supply and filtered by the capacitor C13. The output end of the adjustable voltage regulator U4 outputs a DC voltage, and the output end is connected to the connection point of the resistor R22 and the resistor R18. The Royer push-pull self-excitation circuit includes: a resistor R23, an electrolytic capacitor C15, an electrolytic capacitor C19, a resistor R19, a resistor R24, a capacitor C20, a capacitor C14, a capacitor C17, a transistor Q1, a transistor Q2 and a transformer T1, the transformer includes: a first transformer primary side, a second transformer primary side and a transformer secondary side, the DC voltage output by the adjustable voltage regulator U4 is grounded through the electrolytic capacitor C15 and connected to the center tap of the first transformer primary side, the DC voltage output by the adjustable voltage regulator U4 is grounded through the resistor R23, the capacitor C20 and an electrolytic capacitor C19 connected to the center tap of the primary side of the second transformer, the opposite-name terminals of the primary side of the first transformer are connected to the same-name terminals of the primary side of the second transformer through a transistor Q1 and a resistor R19, the same-name terminals of the primary side of the first transformer are connected to the opposite-name terminals of the primary side of the second transformer through a transistor Q2 and a resistor R24, the collector of the transistor Q1 is connected to its own base through a capacitor C14, the collector of the transistor Q2 is connected to its own base through a capacitor C17, the emitters of the transistors Q1 and Q2 are grounded, and the secondary side of the transformer outputs an AC high voltage; The voltage doubling rectifier circuit includes: a high-voltage capacitor C16, a high-voltage capacitor C18, a high-voltage diode D1, and a high-voltage diode D2. The AC high voltage output by the secondary side of the transformer is connected in series with the high-voltage capacitor C16 and then in parallel with the high-voltage diode D1. The high-voltage diode D2 is connected in series with the high-voltage diode D1 and then in parallel with the high-voltage capacitor C18. The high-voltage capacitor C18 is connected in parallel with the load resistor R25. One end of the load resistor R25 outputs a DC high voltage through the current limiting resistor R20 and the current limiting resistor R21.

8. The cold cathode ionization gauge drive acquisition circuit according to claim 1, characterized in that: The nonlinear compensation operation conditioning circuit includes: an operational amplifier U2B, an operational amplifier U2A, a diode D7, a diode D8, a diode D9, a resistor R25, a resistor R26, a resistor R27, a resistor R28, a resistor R29, a resistor R30, a resistor R31, a resistor R32, a resistor R33, a resistor R34, a resistor R35, a resistor R36, a capacitor C20, a capacitor C21, and a capacitor C22; the output of the ion flow logarithm acquisition circuit is connected to the inverting input terminal of the operational amplifier U2B through the resistor R35, and the operational amplifier The non-inverting input terminal of the operational amplifier U2B is grounded via a resistor R36, the positive and negative power supply terminals of the operational amplifier U2B are connected to the positive and negative power supplies and are filtered via capacitors C22 and C21, the output of the operational amplifier U2B is connected to its own inverting input terminal via a resistor R33, the resistor R33 is connected in parallel with a capacitor C20, the capacitor C20 is connected in parallel with a diode D9, the cathode of the diode D9 is connected to a reference voltage source via a resistor R31, and the output of the operational amplifier U2B is connected to the inverting input terminal of the operational amplifier U2A via a resistor R34; The control signal is connected to the inverting input terminal of the operational amplifier U2A through the nonlinear compensation branch. The inverting input terminal of the operational amplifier U2A is connected to its own output terminal through the parallel resistor R27 and the diode D7. The non-inverting input terminal of the operational amplifier U2A is grounded through the resistor R32. The output terminal of the operational amplifier U2A outputs the operational acquisition voltage for input into the acquisition system.

9. The cold cathode ionization gauge drive acquisition circuit according to claim 8, characterized in that: The nonlinear compensation branch includes: a reference voltage source, a resistor R25, a resistor R28, a diode D8, a resistor R26, a resistor R29, a resistor R30, and a potentiometer VR3. The reference voltage source is connected to the inverting input terminal of the operational amplifier U2A through the resistor R25, the resistor R28, the resistor R29, and the resistor R30. The connection point of the resistor R28 and the resistor R29 is connected to the control signal output by the current monitoring circuit. The connection point of the resistor R25 and the resistor R28 is connected to the inverting input terminal of the operational amplifier U2A through the diode D8, the resistor R26, and the potentiometer VR3.

10. The cold cathode ionization gauge drive acquisition circuit according to claim 9, characterized in that: When the ion current signal is less than the threshold, the control signal voltage output by the current monitoring circuit Maintained at 0V, at this time only the signal output by operational amplifier U2B enters operational amplifier U2A, and the output voltage of operational amplifier U2A is: , is the output voltage of operational amplifier U2B, which is related to the size of the ion flow; When the circuit enters the constant current mode through the negative feedback loop composed of the current monitoring circuit and the voltage-controlled high-voltage drive circuit, the voltage signal output by the ion current logarithmic acquisition circuit will be maintained at 0V. The output fixed value is included in the addition operation, and the control signal voltage output by the current monitoring circuit Starting from 0V and changing towards negative voltage, before diode D8 turns on, only resistors R29 and R30 participate in the feedback operation. At this time, the voltage output by operational amplifier U2A is: , the control signal voltage After diode D8 is turned on, resistor R26 and potentiometer VR3 also participate in the feedback operation. At this time, the voltage output by operational amplifier U2A is: ,in is the forward voltage drop of diode D7, is the voltage applied to the cathode of diode D7.

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