Filament power supply of ion source of surface thermal ionization mass spectrometer

Abstract

The invention discloses a filament power supply of a surface thermal ionization mass spectrometer ion source, which comprises a power supply, an isolation transformation unit, an MCU control unit, a series voltage stabilizing circuit, a proportional integral constant current control circuit, an output driving circuit, a current and voltage monitoring circuit and an indication control panel, the proportional-integral constant-current control circuit adopting negative feedback is established and has the advantages of being high in control precision and current stability and the like, in addition, the current and voltage monitoring circuit collects and outputs current signals and voltage signals to the MCU control unit, the MCU control unit controls the proportional-integral constant-current control circuit according to the current signals and the voltage signals, and therefore the control precision of the proportional-integral constant-current control circuit is improved. Therefore, the output current of the output driving circuit is controlled and corrected, and the filament current is ensured to be stabilized at a set target value. And the current control precision and the current output stability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal ionization mass spectrometers, and particularly to a filament power supply for an ion source of a surface thermal ionization mass spectrometer. Background Art

[0002] A surface thermal ionization mass spectrometer is an advanced analytical instrument, mainly used for high-precision isotope ratio determination in the fields of geochemistry, cosmochemistry, nuclear science, geology, etc., and can also be applied to atomic weight measurement and high-precision isotope dilution analysis. Its basic principle is to smear the test sample substance on the surface of a metal strip with metals such as Re and Ta, heat the metal strip through a filament power supply device, evaporate and ionize the substance to be measured to generate ions, and under the high-voltage electric field of the ion optical lens, the ions are energized and accelerated and focused to form an ion beam, which is transmitted to the mass analyzer. After the ion beam is mass-separated, the ions with the same mass number are refocused, pass through the entrance slit of the ion receiver according to the mass-to-charge ratio and enter the collector, and then are converted into a voltage through a microcurrent amplification circuit, and finally the voltage signal is collected, processed and analyzed to finally obtain the sample isotope abundance ratio data.

[0003] In the prior art, the filament current of the ion source of the thermal ionization mass spectrometer is adjusted by a linear device, with low current stability, low control accuracy and low automation level. And it cannot adapt to the stability of the load resistance change caused by filament aging. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies and propose a filament power supply for an ion source of a surface thermal ionization mass spectrometer to solve the technical problem of low current stability of the filament power supply in the prior art.

[0005] To achieve the above technical purpose, the present invention adopts the following technical solutions: The present invention provides a filament power supply for an ion source of a surface thermal ionization mass spectrometer, including: A power supply, an isolation transformer unit, an MCU control unit, a series voltage regulator circuit, a proportional-integral constant current control circuit, an output drive circuit, a current and voltage monitoring circuit, and an indication control panel. The power supply is electrically connected to the isolation transformer unit and the MCU control unit. The isolation transformer unit is electrically connected to and supplies power to the series voltage regulator circuit and the output drive circuit. The proportional-integral constant current control circuit is electrically connected to the series voltage regulator circuit. The series voltage regulator circuit provides a stable voltage to the proportional-integral constant current control circuit. The proportional-integral constant current control circuit is electrically connected to the output drive circuit and the MCU control unit, receives the control signal from the MCU control unit and the current feedback from the output drive circuit, and outputs an adjustable current to the output drive circuit. The current and voltage monitoring circuit is electrically connected to the MCU control unit and the output drive circuit, monitors the current and voltage of the output drive circuit, and sends them to the MCU control unit. The indication control panel is electrically connected to the MCU control unit. The MCU control unit generates a control signal based on the signal from the indication control panel and the monitoring result of the current and voltage monitoring circuit, and sends it to the proportional-integral constant current control circuit.

[0006] In some embodiments, the isolation transformer unit includes an isolation transformer. The high-voltage side of the isolation transformer is electrically connected to the power supply, and the low-voltage side of the isolation transformer is electrically connected to the series voltage regulator circuit and the output drive circuit.

[0007] In some embodiments, the MCU control unit includes a control chip U1, an optical fiber communication module JOT1, an optical fiber communication module JOT2, an optical fiber communication module JOT3, and an optical fiber communication module JOT4. The PA4 and PA6 pins of the control chip U1 are electrically connected to the TXP and RXP pins of the optical fiber communication module JOT4 respectively. The PA7 pin of the control chip U1 is electrically connected to the TXP pin of the optical fiber communication module JOT3. The PA5 pin of the control chip U1 is electrically connected to the TXP pin of the optical fiber communication module JOT3. The PA8 pin of the control chip U1 is electrically connected to the TXP pin of the optical fiber communication module JOT1. The optical fiber communication module JOT1, the optical fiber communication module JOT2, the optical fiber communication module JOT3, and the optical fiber communication module JOT4 are electrically connected to the current and voltage monitoring circuit and the proportional-integral constant current control circuit through the SPI bus.

[0008] In some embodiments, the series voltage regulator circuit includes a rectifier bridge B2, a polarized capacitor C9, a triode Q9, a resistor R15, a sampling resistor R19, a sampling resistor R20, a sampling resistor R21, an operational amplifier U2, a voltage stabilizing diode DZ3, and a voltage stabilizing diode DZ4. The rectifier bridge B2 is electrically connected to one end of the resistor R15, the anode of the polarized capacitor C9, and the collector of the triode Q9 to form a filtered bridge rectifier circuit. The other end of the resistor R15 and the base of the triode Q9 are electrically connected to the cathode of the voltage stabilizing diode DZ3. The anode of the voltage stabilizing diode DZ3 is electrically connected to the 6th pin of the operational amplifier U2. The 2nd pin of the operational amplifier U2 is electrically connected to one end of the sampling resistor R19, one end of the sampling resistor R20, and one end of the sampling resistor R21. The other end of the sampling resistor R19 is electrically connected to the emitter of the triode Q9. The other ends of the sampling resistor R20 and the sampling resistor R21 are grounded. The 3rd pin of the operational amplifier U2 is electrically connected to the cathode of the voltage stabilizing diode DZ4, and the anode of the voltage stabilizing diode DZ4 is grounded.

[0009] In some embodiments, the proportional-integral constant current control circuit includes an operational amplifier U3, a digital potentiometer U4, a triode Q10, and a triode Q12. The digital potentiometer U4 is electrically connected to the MCU control unit through an SPI bus. The 11th pin of the digital potentiometer U4 is electrically connected to the 3rd pin of the operational amplifier U3. The 2nd pin of the operational amplifier U3 is used as a negative feedback input terminal and is electrically connected to the output driving circuit. The 6th pin of the operational amplifier U3 is electrically connected to the base of the triode Q12. The collector of the triode Q12 is electrically connected to the series voltage regulator circuit. The emitter of the triode Q12 is electrically connected to the base of the triode Q10. The emitter of the triode Q10 forms an output terminal and is electrically connected to the output driving circuit.

[0010] In some embodiments, the output driving circuit includes a rectifier bridge B1, capacitors C1, C2, C3, C4, C5, C6, transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, a shunt FL1, and a resistor R10. The rectifier bridge B1 is electrically connected to one ends of the capacitors C1, C2, C3, C4, C5, C6, the collectors of the transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8. The other ends of the capacitors C1, C2, C3, C4, C5, C6 are grounded. The bases of the transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 are electrically connected to the proportional integral constant current control circuit. The emitters of the transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 are electrically connected to one end of the shunt FL1. The other end of the shunt FL1 is electrically connected to one end of the resistor R10. The other end of the resistor R10 forms a current output terminal and is electrically connected to the proportional integral constant current control circuit.

[0011] In some embodiments, a filament disconnection detection circuit is further included. The filament disconnection detection circuit has a filament detection terminal and is electrically connected to the MCU control unit, and is configured to detect the disconnection condition of the filament and form a signal to be sent to the MCU control unit and the indication control panel.

[0012] In some embodiments, the filament disconnection detection circuit includes transistors Q11, zener diodes DZ5, DZ6. The base of the transistor Q11 is electrically connected to the anode of the zener diode DZ6. The cathode of the zener diode DZ6 is electrically connected to the cathode of the zener diode DZ5. The anode of the zener diode DZ5 forms the filament detection terminal. The emitter of the transistor Q11 is grounded. The collector of the transistor Q11 is electrically connected to the MCU control unit and the indication control panel.

[0013] In some embodiments, the current-voltage monitoring circuit includes a power supply chip U5, an operational amplifier U6, an operational amplifier U7, an ADC chip U8, an optical fiber transceiver JOR1, an optical fiber transceiver JOR2, an optical fiber transceiver JOR3, and an optical fiber transceiver JOR4. The Vout pin of the power supply chip U5 is electrically connected to the non-inverting input terminal of the operational amplifier U6. The non-inverting input terminal and the inverting input terminal of the operational amplifier U7 are electrically connected to the filament. The output terminal of the operational amplifier U7 and the output terminal of the operational amplifier U6 are electrically connected to the ADC chip U8. The optical fiber transceiver JOR1, the optical fiber transceiver JOR2, the optical fiber transceiver JOR3, and the optical fiber transceiver JOR4 are electrically connected to the ADC chip U8 and the SPI bus.

[0014] In some embodiments, the specific model of the control chip U1 is STM32F103C8T6.

[0015] Compared with the prior art, the filament power supply of the surface thermal ionization mass spectrometer ion source provided by the present invention includes a power supply, an isolation transformer unit, an MCU control unit, a series voltage regulator circuit, a proportional-integral constant current control circuit, an output drive circuit, a current-voltage monitoring circuit, and an indication control panel. The power supply is electrically connected to the isolation transformer unit and the MCU control unit. The isolation transformer unit is electrically connected to and supplies power to the series voltage regulator circuit and the output drive circuit. The proportional-integral constant current control circuit is electrically connected to the series voltage regulator circuit. The series voltage regulator circuit provides a stable voltage to the proportional-integral constant current control circuit. The proportional-integral constant current control circuit is electrically connected to the output drive circuit and the MCU control unit, receives the control signal of the MCU control unit and the current feedback of the output drive circuit, and outputs an adjustable current to the output drive circuit. The current-voltage monitoring circuit is electrically connected to the MCU control unit and the output drive circuit, monitors the current and voltage of the output drive circuit, and sends them to the MCU control unit. The indication control panel is electrically connected to the MCU control unit. The MCU control unit generates a control signal according to the signal of the indication control panel and the monitoring result of the current-voltage monitoring circuit, and sends it to the proportional-integral constant current control circuit. The present invention constructs a proportional-integral constant current control circuit with negative feedback, which has the characteristics of high control accuracy and high current stability. In addition, the current-voltage monitoring circuit collects the output current signal and voltage signal to the MCU control unit, and the MCU control unit controls the proportional-integral constant current control circuit accordingly to control and correct the output current of the output drive circuit to ensure that the filament current is stable at the set target value. The current control accuracy and the stability of the current output are improved.

[0016] The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and be able to implement it according to the content of the specification, the preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. The specific implementation manners of the present invention are given in detail by the following embodiments and their accompanying drawings. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the module of the filament power supply of the ion source of the surface thermal ionization mass spectrometer provided by the present invention; Figure 2 is Figure 1 the circuit diagram of the MCU control unit in; Figure 3 is Figure 1 the circuit diagram of the series voltage regulator circuit in; Figure 4 is Figure 1 the circuit diagram of the proportional integral constant current control circuit in; Figure 5 is Figure 1 the circuit diagram of the output drive circuit in; Figure 6 is Figure 1 the circuit diagram of the filament break detection circuit in; Figure 7 is Figure 1 the circuit diagram of the current and voltage monitoring circuit in; Figure 8 is Figure 1 the circuit diagram of the indication control panel in.

[0018] Description of the Reference Numerals: 1 - Power supply, 2 - Isolation transformer unit, 3 - MCU control unit, 4 - Series voltage regulator circuit, 5 - Proportional integral constant current control circuit, 6 - Output drive circuit, 7 - Current and voltage monitoring circuit, 8 - Indication control panel, 9 - Filament break detection circuit. Detailed Embodiments

[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] Please refer to Figure 1-8; The present invention provides a filament power supply for an ion source of a surface ionization mass spectrometer, comprising: a power supply 1, an isolation transformer unit 2, an MCU control unit 3, a series voltage regulator circuit 4, a proportional-integral constant current control circuit 5, an output drive circuit 6, a current-voltage monitoring circuit 7, and an indication control panel 8. The power supply 1 is electrically connected to the isolation transformer unit 2 and the MCU control unit 3. The isolation transformer unit 2 is electrically connected to and supplies power to the series voltage regulator circuit 4 and the output drive circuit 6. The proportional-integral constant current control circuit 5 is electrically connected to the series voltage regulator circuit 4. The series voltage regulator circuit 4 provides a stable voltage to the proportional-integral constant current control circuit 5. The proportional-integral constant current control circuit 5 is electrically connected to the output drive circuit 6 and the MCU control unit 3, receives the control signal from the MCU control unit 3 and the current feedback from the output drive circuit 6, and outputs an adjustable current to the output drive circuit 6. The current-voltage monitoring circuit 7 is electrically connected to the MCU control unit 3 and the output drive circuit 6, monitors the current and voltage of the output drive circuit 6 and sends them to the MCU control unit 3. The indication control panel 8 is electrically connected to the MCU control unit 3. The MCU control unit 3 generates a control signal according to the signal of the indication control panel 8 and the monitoring result of the current-voltage monitoring circuit 7 and sends it to the proportional-integral constant current control circuit 5.

[0021] In the present invention, the filament power supply of the surface ionization mass spectrometer ion source includes a power supply 1, an isolation transformer unit 2, an MCU control unit 3, a series voltage regulator circuit 4, a proportional integral constant current control circuit 5, an output drive circuit 6, a current and voltage monitoring circuit 7, and an indication control panel 8. The power supply 1 is electrically connected to the isolation transformer unit 2 and the MCU control unit 3. The isolation transformer unit 2 is electrically connected to and supplies power to the series voltage regulator circuit 4 and the output drive circuit 6. The proportional integral constant current control circuit 5 is electrically connected to the series voltage regulator circuit 4. The series voltage regulator circuit 4 provides a stable voltage to the proportional integral constant current control circuit 5. The proportional integral constant current control circuit 5 is electrically connected to the output drive circuit 6 and the MCU control unit 3, receives the control signal of the MCU control unit 3 and the current feedback of the output drive circuit 6, and outputs an adjustable current to the output drive circuit 6. The current and voltage monitoring circuit 7 is electrically connected to the MCU control unit 3 and the output drive circuit 6, monitors the current and voltage of the output drive circuit 6, and sends them to the MCU control unit 3. The indication control panel 8 is electrically connected to the MCU control unit 3. The MCU control unit 3 generates a control signal according to the signal of the indication control panel 8 and the monitoring result of the current and voltage monitoring circuit 7, and sends it to the proportional integral constant current control circuit 5. In the present invention, a proportional integral constant current control circuit with negative feedback is built, which has the characteristics of high control accuracy and high current stability. In addition, the current and voltage monitoring circuit collects the output current signal and voltage signal to the MCU control unit 3, and the MCU control unit 3 controls the proportional integral constant current control circuit 5 with this, so as to control and correct the output current of the output drive circuit 6, ensuring that the filament current is stable at the set target value. The current control accuracy and the stability of the current output are improved.

[0022] Specifically, the power supply 1 is a common 220V AC power supply on the market, which is a conventional device in this field and is well-known to those skilled in the art, so it will not be elaborated here.

[0023] Specifically, the isolation transformer unit 2 includes an isolation transformer. The high-voltage side of the isolation transformer is electrically connected to the power supply 1, and the low-voltage side of the isolation transformer is electrically connected to the series voltage regulator circuit 4 and the output drive circuit 6. The isolation transformer is designed with an isolation voltage ≥ 20kV, which fully ensures the safety of circuit isolation.

[0024] Specifically, as Figure 2As shown, the MCU control unit 3 includes a control chip U1, an optical fiber communication module JOT1, an optical fiber communication module JOT2, an optical fiber communication module JOT3, and an optical fiber communication module JOT4. The PA4 pin and PA6 pin of the control chip U1 are electrically connected to the TXP pin and RXP pin of the optical fiber communication module JOT4 respectively. The PA7 pin of the control chip U1 is electrically connected to the TXP pin of the optical fiber communication module JOT3. The PA5 pin of the control chip U1 is electrically connected to the TXP pin of the optical fiber communication module JOT3. The PA8 pin of the control chip U1 is electrically connected to the TXP pin of the optical fiber communication module JOT1. The optical fiber communication module JOT1, the optical fiber communication module JOT2, the optical fiber communication module JOT3, and the optical fiber communication module JOT4 are electrically connected to the current and voltage monitoring circuit 7 and the proportional integral constant current control circuit 5 through the SPI bus.

[0025] Further, the specific model of the control chip U1 is STM32F103C8T6.

[0026] Specifically, the series voltage regulator circuit 4 includes a rectifier bridge B2, a polar capacitor C9, a triode Q9, a resistor R15, a sampling resistor R19, a sampling resistor R20, a sampling resistor R21, an operational amplifier U2, a voltage stabilizing diode DZ3, and a voltage stabilizing diode DZ4. The rectifier bridge B2 is electrically connected to one end of the resistor R15, the anode of the polar capacitor C9, and the collector of the triode Q9 to form a bridge rectifier circuit filtering. The other end of the resistor R15 and the base of the triode Q9 are electrically connected to the cathode of the voltage stabilizing diode DZ3. The anode of the voltage stabilizing diode DZ3 is electrically connected to the 6th pin of the operational amplifier U2. The 2nd pin of the operational amplifier U2 is electrically connected to one end of the sampling resistor R19, one end of the sampling resistor R20, and one end of the sampling resistor R21. The other end of the sampling resistor R19 is electrically connected to the emitter of the triode Q9. The other ends of the sampling resistor R20 and the sampling resistor R21 are grounded. The 3rd pin of the operational amplifier U2 is electrically connected to the cathode of the voltage stabilizing diode DZ4. The anode of the voltage stabilizing diode DZ4 is grounded.

[0027] The AC power supply output by the isolation transformer is filtered by the bridge rectifier circuit composed of the rectifier bridge B2 and the polar capacitor C9 to generate a DC power supply. A bias voltage is provided to the base of the triode Q9 through the resistor R15 to turn on the triode Q9. The DC current flows from the collector to the emitter of the triode Q9, and a DC voltage is output. A negative feedback circuit is formed by the operational amplifier U2, the sampling resistors R19 - R21, the reference voltage formed by the zener diode DZ4, etc., to control the base of the triode Q9, and finally a highly stable +15V and -8.2V power supply is generated for powering the proportional integral constant current control circuit 5.

[0028] Specifically, the proportional integral constant current control circuit 5 includes an operational amplifier U3, a digital potentiometer U4, a triode Q10, and a triode Q12. The digital potentiometer U4 is electrically connected to the MCU control unit 3 through the SPI bus. The 11th pin of the digital potentiometer U4 is electrically connected to the 3rd pin of the operational amplifier U3. The 2nd pin of the operational amplifier U3 is used as the negative feedback input terminal and is electrically connected to the output drive circuit 6. The 6th pin of the operational amplifier U3 is electrically connected to the base of the triode Q12. The collector of the triode Q12 is electrically connected to the series voltage regulator circuit 4. The emitter of the triode Q12 is electrically connected to the base of the triode Q10. The emitter of the triode Q10 forms an output terminal and is electrically connected to the output drive circuit 6.

[0029] The proportional integral constant current control circuit 5 uses the operational amplifier U3 to build a negative feedback constant current control circuit. The sampling voltage signal of the output filament current is introduced into the inverting input terminal of the 2nd pin of the operational amplifier U3 to form a negative feedback control loop. The output terminal of the digital potentiometer at the non-inverting input terminal of the 3rd pin of the operational amplifier U3. The control precision of the digital potentiometer U4 is 1024 taps, and the temperature coefficient is 5ppm, realizing precise adjustment and control. The digital potentiometer U4 is connected to the MCU control unit 3 through the SPI bus for control. The output terminal of the operational amplifier U3 drives the conduction amounts of the two-stage triodes Q12 and Q10, and a control current signal is output through the QD1 port of the base of the triode Q10 to drive the conduction amount of the triode in the output drive circuit of the current, achieving the purpose of precisely controlling the output current magnitude.

[0030] Specifically, the output driving circuit 6 includes a rectifier bridge B1, capacitors C1, C2, C3, C4, C5, C6, transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, a shunt FL1, and a resistor R10. The rectifier bridge B1 is electrically connected to one ends of the capacitors C1, C2, C3, C4, C5, C6, the collector of the transistor Q1, the collector of the transistor Q2, the collector of the transistor Q3, the collector of the transistor Q4, the collector of the transistor Q5, the collector of the transistor Q6, the collector of the transistor Q7, and the collector of the transistor Q8. The other ends of the capacitors C1, C2, C3, C4, C5, C6 are grounded. The bases of the transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 are electrically connected to the proportional-integral constant-current control circuit 5. The emitters of the transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 are electrically connected to one end of the shunt FL1. The other end of the shunt FL1 is electrically connected to one end of the resistor R10. The other end of the resistor R10 forms a current output terminal and is electrically connected to the proportional-integral constant-current control circuit 5.

[0031] The AC power supply output by the isolation transformer passes through the bridge rectifier and filter circuit composed of the rectifier bridge B1 and the capacitors C1 - C6 to generate a driving DC power supply, which is provided to the collectors of 8 parallel-driven transistors Q1 - Q8. The bases of the transistors Q1 - Q8 receive the control signal QD1 of the proportional-integral constant-current control circuit 5. By controlling the conduction amount of the transistors Q1 - Q8, a linearly controllable DC current is output to achieve the purpose of precisely controlling the magnitude of the output current.

[0032] Specifically, it further includes a filament break detection circuit 9. The filament break detection circuit 9 has a filament detection end and is electrically connected to the MCU control unit 3, and is used for detecting the break situation of the filament and forming a signal to be sent to the MCU control unit 3 and the indication control panel 8.

[0033] Further, the filament disconnection detection circuit 9 includes a triode Q11, a voltage stabilizing diode DZ5, and a voltage stabilizing diode DZ6. The base of the triode Q11 is electrically connected to the anode of the voltage stabilizing diode DZ6. The cathode of the voltage stabilizing diode DZ6 is electrically connected to the cathode of the voltage stabilizing diode DZ5. The anode of the voltage stabilizing diode DZ5 forms the filament detection terminal. The emitter of the triode Q11 is grounded. The collector of the triode Q11 is electrically connected to the MCU control unit 3 and the indication control panel 8.

[0034] When the filament is normal, since the filament resistance is very low and the output terminal is approximately in a short - circuit state, the voltage at the filament detection terminal is very low, and the triode Q11 is in a cut - off state without output.

[0035] When the filament is disconnected, the output terminal is equivalent to an open circuit. All the driving triodes of the output driving circuit 6 are turned on. The voltage at the filament detection terminal is about +15V. The triode Q11 is in a conducting state, and the collector of the triode Q11 outputs a signal. This signal is directly transmitted to the indication control panel 8 and the MCU control unit 3.

[0036] Specifically, the current - voltage monitoring circuit 7 includes a power supply chip U5, an operational amplifier U6, an operational amplifier U7, an ADC chip U8, optical fiber transceivers JOR1, JOR2, JOR3, and JOR4. The Vout pin of the power supply chip U5 is electrically connected to the non - inverting input terminal of the operational amplifier U6. The non - inverting input terminal and the inverting input terminal of the operational amplifier U7 are electrically connected to the filament. The output terminal of the operational amplifier U7 and the output terminal of the operational amplifier U6 are electrically connected to the ADC chip U8. The optical fiber transceivers JOR1, JOR2, JOR3, and JOR4 are electrically connected to the ADC chip U8 and the SPI bus.

[0037] The power supply chip U5 is a high - precision reference voltage chip with a temperature coefficient of 3ppm. The power supply chip U5 outputs a reference voltage of 2.5V. Through the voltage follower built by the operational amplifier U6, it provides a stable and reliable reference voltage for voltage sampling of the operational amplifier U7 and the ADC chip U8 respectively. The operational amplifier U7 is a 2 - channel precision operational amplifier, which is used to collect the signals of the output current of the filament power supply device and the +15V working voltage, and outputs them to the ADC chip U8. The ADC chip U8 is a 24 - bit high - precision analog - to - digital conversion chip, which is used to convert the voltage signal output by the operational amplifier U7 into a digital signal and transmit it to the MCU control unit 3 through the SPI bus.

[0038] Advantages of the present invention: The filament power supply of the ion source of the surface thermal ionization mass spectrometer provided by the present invention includes a power supply, an isolation transformer unit, an MCU control unit, a series voltage regulator circuit, a proportional-integral constant current control circuit, an output driver circuit, a current and voltage monitoring circuit, and an indication control panel. The power supply is electrically connected to the isolation transformer unit and the MCU control unit. The isolation transformer unit is electrically connected to and supplies power to the series voltage regulator circuit and the output driver circuit. The proportional-integral constant current control circuit is electrically connected to the series voltage regulator circuit. The series voltage regulator circuit provides a stable voltage to the proportional-integral constant current control circuit. The proportional-integral constant current control circuit is electrically connected to the output driver circuit and the MCU control unit, receives the control signal of the MCU control unit and the current feedback of the output driver circuit, and outputs an adjustable current to the output driver circuit. The current and voltage monitoring circuit is electrically connected to the MCU control unit and the output driver circuit, monitors the current and voltage of the output driver circuit, and sends them to the MCU control unit. The indication control panel is electrically connected to the MCU control unit. The MCU control unit generates a control signal according to the signal of the indication control panel and the monitoring result of the current and voltage monitoring circuit, and sends it to the proportional-integral constant current control circuit. The present invention constructs a proportional-integral constant current control circuit with negative feedback, which has the characteristics of high control accuracy and high current stability. In addition, the current and voltage monitoring circuit collects the output current signal and voltage signal to the MCU control unit, and the MCU control unit controls the proportional-integral constant current control circuit accordingly to control and correct the output current of the output driver circuit to ensure that the filament current is stable at the set target value. The current control accuracy and the stability of the current output are improved.

[0039] The specific embodiments of the present invention described above do not limit the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A filament power supply for an ion source of a surface thermal ionization mass spectrometer, characterized in that: It includes: A power supply, an isolation transformer unit, an MCU control unit, a series voltage regulator circuit, a proportional-integral constant current control circuit, an output drive circuit, a current and voltage monitoring circuit, and an indication control panel, wherein the power supply is electrically connected to the isolation transformer unit and the MCU control unit, and the isolation transformer unit is electrically connected to the series voltage regulator circuit and the output drive circuit and supplies power; the proportional-integral constant current control circuit is electrically connected to the series voltage regulator circuit, and the series voltage regulator circuit provides a stable voltage to the proportional-integral constant current control circuit, the proportional-integral constant current control circuit is electrically connected to the output drive circuit and the MCU control unit, receives a control signal from the MCU control unit and a current feedback from the output drive circuit, and outputs an adjustable current to the output drive circuit, the current and voltage monitoring circuit is electrically connected to the MCU control unit and the output drive circuit, monitors the current and voltage of the output drive circuit and sends it to the MCU control unit, the indication control panel is electrically connected to the MCU control unit, and the MCU control unit generates a control signal according to the signal of the indication control panel and the monitoring result of the current and voltage monitoring circuit and sends it to the proportional-integral constant current control circuit.

2. The filament power supply of the surface thermal ionization mass spectrometer ion source according to claim 1, characterized in that: The isolation transformer unit includes an isolation transformer, a high voltage side of the isolation transformer is electrically connected to the power supply, and a low voltage side of the isolation transformer is electrically connected to the series voltage stabilizing circuit and the output drive circuit.

3. The filament power supply of the surface thermal ionization mass spectrometer ion source according to claim 2, characterized in that: The MCU control unit includes a control chip U1, an optical fiber communication module JOT1, an optical fiber communication module JOT2, an optical fiber communication module JOT3, and an optical fiber communication module JOT4. The PA4 pin and the PA6 pin of the control chip U1 are electrically connected to the TXP pin and the RXP pin of the optical fiber communication module JOT4, respectively. The PA7 pin of the control chip U1 is electrically connected to the TXP pin of the optical fiber communication module JOT3, respectively. The PA5 pin of the control chip U1 is electrically connected to the TXP pin of the optical fiber communication module JOT3, respectively. The PA8 pin of the control chip U1 is electrically connected to the TXP pin of the optical fiber communication module JOT1, respectively. The optical fiber communication module JOT1, the optical fiber communication module JOT2, the optical fiber communication module JOT3, and the optical fiber communication module JOT4 are electrically connected to the current and voltage monitoring circuit and the proportional integral constant current control circuit through an SPI bus.

4. The filament power supply of the surface thermal ionization mass spectrometer ion source according to claim 1, characterized in that: The series voltage stabilizing circuit includes a rectifier bridge B2, a polar capacitor C9, a transistor Q9, a resistor R15, a sampling resistor R19, a sampling resistor R20, a sampling resistor R21, an operational amplifier U2, a voltage stabilizing diode DZ3, and a voltage stabilizing diode DZ4. The rectifier bridge B2 is electrically connected to one end of the resistor R15, the anode of the polar capacitor C9, and the collector of the transistor Q9 to form a bridge rectifier circuit filter; the other end of the resistor R15 and the base of the transistor Q9 are electrically connected to the cathode of the voltage stabilizing diode DZ3. The anode of the diode DZ3 is electrically connected to pin No. 6 of the operational amplifier U2, pin No. 2 of the operational amplifier U2 is electrically connected to one end of the sampling resistor R19, one end of the sampling resistor R20, and one end of the sampling resistor R21, the other end of the sampling resistor R19 is electrically connected to the emitter of the transistor Q9, the other end of the sampling resistor R20 and the other end of the sampling resistor R21 are grounded, pin No. 3 of the operational amplifier U2 is electrically connected to the cathode of the Zener diode DZ4, and the anode of the Zener diode DZ4 is grounded.

5. The filament power supply of the surface thermal ionization mass spectrometer ion source according to claim 1, characterized in that: The proportional-integral constant current control circuit includes an operational amplifier U3, a digital potentiometer U4, a transistor Q10, and a transistor Q12. The digital potentiometer U4 is electrically connected to the MCU control unit via an SPI bus. Pin 11 of the digital potentiometer U4 is electrically connected to pin 3 of the operational amplifier U3. Pin 2 of the operational amplifier U3 is electrically connected to the output drive circuit as a negative feedback input terminal. Pin 6 of the operational amplifier U3 is electrically connected to the base of the transistor Q12. The collector of the transistor Q12 is electrically connected to the series voltage stabilizing circuit. The emitter of the transistor Q12 is electrically connected to the base of the transistor Q10. The emitter of the transistor Q10 forms an output terminal and is electrically connected to the output drive circuit.

6. The filament power supply of the surface thermal ionization mass spectrometer ion source according to claim 1, characterized in that: The output drive circuit includes a rectifier bridge B1, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a transistor Q1, a transistor Q2, a transistor Q3, a transistor Q4, a transistor Q5, a transistor Q6, a transistor Q7, a transistor Q8, a shunt FL1 and a resistor R10. The rectifier bridge B1 is connected to one end of the capacitor C1, one end of the capacitor C2, one end of the capacitor C3, and one end of the capacitor C4. The collector of the transistor Q1, the collector of the transistor Q2, the collector of the transistor Q3, the collector of the transistor Q4, the collector of the transistor Q5, the collector of the transistor Q6, the collector of the transistor Q7, and the collector of the transistor Q8 are electrically connected, and the other end of the capacitor C1, the other end of the capacitor C2, the other end of the capacitor C3, The other end of the capacitor C4, the other end of the capacitor C5, and the other end of the capacitor C6 are grounded; the base of the transistor Q1, the base of the transistor Q2, the base of the transistor Q3, the base of the transistor Q4, the base of the transistor Q5, the base of the transistor Q6, the base of the transistor Q7, and the base of the transistor Q8 are electrically connected to the proportional-integral constant current control circuit; the emitter of the transistor Q1, the emitter of the transistor Q2, the emitter of the transistor Q3, the emitter of the transistor Q4, the emitter of the transistor Q5, the emitter of the transistor Q6, the emitter of the transistor Q7, and the emitter of the transistor Q8 are electrically connected to one end of the shunt FL1; the other end of the shunt FL1 is electrically connected to one end of the resistor R10; the other end of the resistor R10 forms a current output end and is electrically connected to the proportional-integral constant current control circuit.

7. The filament power supply of the surface thermal ionization mass spectrometer ion source according to claim 1, characterized in that: It also includes a filament disconnection detection circuit, which has a filament detection end and is electrically connected to the MCU control unit, and is used to detect the disconnection of the filament and form a signal to send to the MCU control unit and the indication control panel.

8. The filament power supply of the surface thermal ionization mass spectrometer ion source according to claim 7, characterized in that: The filament disconnection detection circuit includes a transistor Q11, a Zener diode DZ5, and a Zener diode DZ6. The base of the transistor Q11 is electrically connected to the anode of the Zener diode DZ6, the cathode of the Zener diode DZ6 is electrically connected to the cathode of the Zener diode DZ5, the anode of the Zener diode DZ5 forms the filament detection end, the emitter of the transistor Q11 is grounded, and the collector of the transistor Q11 is electrically connected to the MCU control unit and the indication control panel.

9. The filament power supply of the surface thermal ionization mass spectrometer ion source according to claim 1, characterized in that: The current and voltage monitoring circuit includes a power chip U5, an operational amplifier U6, an operational amplifier U7, an ADC chip U8, a fiber optic transceiver JOR1, a fiber optic transceiver JOR2, a fiber optic transceiver JOR3, and a fiber optic transceiver JOR4. The Vout pin of the power chip U5 is electrically connected to the non-inverting input terminal of the operational amplifier U6, the non-inverting input terminal and the inverting input terminal of the operational amplifier U7 are electrically connected to the filament, the output terminal of the operational amplifier U7 and the output terminal of the operational amplifier U6 are electrically connected to the ADC chip U8, and the fiber optic transceivers JOR1, the fiber optic transceivers JOR2, the fiber optic transceivers JOR3, and the fiber optic transceivers JOR4 are electrically connected to the ADC chip U8 and the SPI bus.

10. The filament power supply of the surface thermal ionization mass spectrometer ion source according to claim 3, characterized in that: The specific model of the control chip U1 is STM32F103C8T6.

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